RU2119648C1 - Cargo weighing gear - Google Patents

Abstract

FIELD: lifting and transportation engineering. SUBSTANCE: cargo weighing ear is designed to weigh cargoes on crane, platform and other scales. Gear incorporates force-measuring transmitters of weight load installed in cargo transporting mechanism, amplification and conversion unit electrically coupled to transmitters, light panel displaying weight loads. Gear is also fitted with temperature-sensitive elements installed in force-measuring transmitters and screening enclosure where amplification and conversion unit made in the form of programmable controller with adding device is mounted with clearance. Enclosure also houses fan and controller has heater and temperature-sensitive resistor electrically coupled to heater and fan. Controller is electrically coupled independently to each temperature-sensitive element and to each force-measuring transmitter. EFFECT: enhanced reliability and accuracy of gear, expanded field of its application. 1 dwg

Description

 The invention relates to the field of lifting and transport engineering, and in particular to devices for weighing goods on crane, platform and other scales.

 Known crane scales containing a freight trolley, on the frame of which are hoisting winches and load cells connected by an electric circuit to a secondary measuring device, and load cells connected in series with the electric circuit [1].

 A disadvantage of the known device is the low reliability of the design, because the failure of one of the load cells due to their serial connection leads to the failure of all the scales and makes it difficult to find an invalid sensor.

In addition, the lack of temperature correction of errors during the operation of crane scales in a wide temperature range from minus 40 ^o C in winter to plus 60 ^o C in summer in hot shops reduce the accuracy of weighing.

 A device is also known that contains from six to eight strain gauge sensors of automatic scales in parallel connection mode [2].

 This device has the same drawbacks that were listed above, since the failure of the strain bridge of one of the load cells entails the unbalance of the balance.

 The closest in technical essence and result to the invention is a device for weighing cargo, comprising a load transport mechanism, load cell load sensors mounted on a load transport mechanism, an amplification-conversion unit electrically connected to the sensors, and a light display panel displaying weight loads [3].

 Devices for weighing cargo of this type are equipped with a radio channel for transmitting information at a distance of up to 1000 m to a personal computer.

 The disadvantages of the known device adopted for the prototype are the lack of reliability of the scales, because the reliability of the balance is based on the reliability of the load cell and its measuring channel and the failure of the sensor leads to a failure of the entire device, and a high temperature error, especially at the ends of the temperature interval of the device in a sharply continental climate, which reduces the accuracy of weighing and thereby limits the scope of application of the known devices.

 The technical result achieved when using the present invention is to increase the reliability of the device by eliminating the influence of failure of the load cell on the performance of the balance and improving the accuracy of the measurement by taking into account the temperature component of the error on the weighing result.

 To achieve the specified technical result, the known device is additionally equipped with temperature sensors mounted in load cells and a shielding casing, in which the amplifier-converter unit is installed with a gap, made as a programmable controller with a summing device, which is electrically connected to each temperature sensor and load sensor independently, in this case, a fan is mounted in the shielding casing, and in the controller - a heater and thermal resistance, electric finely connected to the controller, heater and fan.

 The invention is illustrated by graphic material, which presents a block diagram of the claimed device.

 The device comprises a cargo transport mechanism, in particular, with a crane beam (1), to which a load is hung using hooks, for example, a bucket (2) with molten metal, load cells (3) with temperature sensors built into them (4), a controller with a summing device (5) mounted in a shielding casing (6) with a fan (7). The controller (5) is electrically connected with load cells (3), temperature sensors (4.12), crane operator panel (8), light electronic display of weight loads (9) and radio station (10) cable network. In the controller (5), a heater (11) and a thermal resistance (12) are mounted, which are electrically connected to the fan (7) and the heater (11). The device can also be equipped with a central computer (13), electrically connected to the central radio station (14). A central computer (13) with a radio station (14) can serve several scales of this type at once.

 The device operates as follows.

 Under the influence of the weight of the bucket (2), force sensors (3), which are strain gauge force sensors, convert the strain value of the sensor elastic element into an electrical signal proportional to the compressive force. The temperature sensors (4), for example, thermistors, made inside the load cells (3), convert the current temperature value into an electrical signal. Electrical signals from the load sensors (3) and thermal resistors (4) are fed to the controller (5), which performs their analog-to-digital conversion and mathematical processing according to an algorithm that compensates for the nonlinearity and temperature errors of the load sensors (3). The weight loads measured by each load cell sensor (3) are summed up in the summing device of the controller (5) and digitally transmitted to the crane operator's indicator (8), light electronic display (9) and via radio via radio stations (10,14) to the central computer ( thirteen).

где
m - общее число силоизмерительных датчиков (каналов);
n - число исправных датчиков (каналов);
P_i - результат измерения по исправному датчику (каналу);
k_i - коэффициент, учитывающий неравномерность распределения нагрузки между датчиками.The controller (5) analyzes the readings on the measuring channels of the force sensors (3) and, when diagnosing a failure of one or several measuring channels, the weighing result is calculated according to the data received from serviceable sensors (3), according to the following formula

Where
m is the total number of load sensors (channels);
n is the number of serviceable sensors (channels);
P _i - the result of measurement by a working sensor (channel);
k _i - coefficient taking into account the uneven distribution of the load between the sensors.

 The result of the calculation does not depend on the readings of the faulty sensor.

 Therefore, the failure of the load sensor (3) does not lead to the failure of the crane balance and the weighing results remain reliable and allow not to interrupt the technological cycle.

 During the normal operation of crane scales, continuous diagnostics of the state of system elements is automatically performed. In case of malfunctions, information about this is displayed on the crane operator panel (8).

 Scales maintain their performance and high accuracy in extreme climatic conditions. High measurement accuracy can be realized provided that the electronic circuits are functioning in fairly stable temperature conditions. Therefore, the controller (5), evaluating the state of the built-in temperature sensor (12), issues commands to turn on either the heater (11) or the fan (7), which cools the controller case with maximum efficiency, which is achieved by the optimal clearance between the shield case (6) and the case controller (5). The air intake for blowing is made from the unheated zone of the workshop. The value of the optimal clearance is calculated based on the performance of the fan (7) and the volume of the controller (5).

Compared with the known technical solution, the device has:
- greater reliability, due to the creation of independent measurement channels for each load sensor, which allows to process the measurement results even with failed load sensors with a slight loss of accuracy;
- greater accuracy by reducing the temperature error and the error from nonlinearity;
- extended scope, due to the increase in the operating temperature range.

The proposed weighing device is designed and manufactured at the TEKHNOAP enterprise and undergoes operational tests at Severstal OJSC and has the following technical characteristics:
- maximum load capacity up to 1000 tons;
- overload capacity of 50%;
- weighing error, not more than 0.1%;
- operating temperature range from -40 ^o C to +65 ^o C;
- readability of data from the scoreboard, not less than 100 m;
- A computer with a radio channel serves six cranes.

Sources of information
1. "Crane scales". Description A.S. USSR N 477098, class B 66 C 13/16 dated 06/13/73

 2. "Strain gages force sensors for automatic scales." DMS-Wagezele als Konstruktionselement zum Einsatz in Fahrzeugwaagen. Wagen und Dosier, 1994, 25 N 6, z. 27-29.

 3. "Crane scales with a digital electronic board KGWl ... 100". EHP Steuerungs- und Wagetechnik Gmbh. Technical description N 3/94/4000/500.

Claims (1)

 A device for weighing cargo, comprising a cargo transport mechanism with load cell load sensors installed thereon, an amplifying and converting unit electrically connected to load cell sensors, and a light display panel for weight loads, characterized in that temperature sensors mounted in the load cell are introduced into the device, a shielding casing in which the amplifier-converter unit is installed with a gap, made in the form of a programmable controller with the sum device, as well as a fan located in the shielding casing, and a heater with thermal resistance, located in the programmable controller, while the programmable controller is electrically connected to each temperature sensor and each load sensor independently, and the thermal resistance is electrically connected to the programmable controller, heater and fan .