JPH0557658U - Microwave moisture analyzer - Google Patents

Abstract

(57) [Summary] [Purpose] In a microwave moisture measuring device, by stabilizing the flow around the sensor head that is inserted into the flow path of the aggregate, the stability of the measured value and the total moisture content are calculated. [Structure] A sensor head having a microwave transmitter and a receiver built-in is formed of a smooth measurement side surface and a substantially semicylindrical back side wall surface continuous with the measurement side surface, and the measurement side surface of the head is an aggregate. The head is installed in the flow path of the aggregate in a direction inclined by about 120 ° with respect to the direction of the flow.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a microwave moisture measuring device for measuring moisture in aggregate for quality control of concrete.

[0002]

[Prior Art]

 As is well known, the amount of water mixed in fresh concrete is an important factor that affects quality retention such as the slump of fresh concrete and the strength of concrete after hardening.

It has been important to determine the amount of water added at this time in consideration of the water content in the aggregate, especially fine sand.

The water content adjustment under such a condition is based on the means such as sampling by manual analysis and the intuition of a skilled person in the past, and recently, the capacitance type water content measuring device and the weight type, the neutral type, Although various types of moisture measuring devices such as infrared type and microwave type are used, these conventional moisture measuring devices have advantages and disadvantages in their measuring methods, and there are many practical problems as a device. , There was still room for improvement.

That is, in the capacitance type, a measurement error occurs depending on the degree of pressing of the sensor with respect to the sand, and it is affected by salt content, and since it is a local measurement, it has a drawback that continuous measurement cannot be performed. However, with the weight method, it takes about 20 seconds for measurement, and it is not possible to perform continuous measurement because it is a local measurement as described above, and moreover, there is a problem with the installation space of the device. The formula requires a measurement time (about 2 minutes), and an expensive fast neutron source is required to improve this. The infrared formula only reacts with the water on the sand surface and changes in the surface color of the sand. However, there are drawbacks such as error.

A conventional microwave moisture meter transmits microwaves from one oscillator, and when hitting the aggregate, the microwaves are absorbed by water molecules in the aggregate, and the attenuated microwaves are transmitted to the other oscillator. The data is received, and the attenuation is converted into the water content in the aggregate and displayed. However, in order to accurately measure the amount of water in the aggregate, it is necessary to ensure that the sand in the sensor part is replaced and that the device does not cause measurement errors due to changes in sand density. Strongly desired.

[0007]

[Problems to be solved by the device]

 Therefore, in order to solve the problems in the microwave moisture measuring device, the present invention is to develop a device in which the measured aggregates in the sensor part are replaced with each other with a certain flowability.

[0008]

[Means for Solving the Problems]

 In order to solve this problem, the present invention forms a sensor head with a built-in microwave transmitter and receiver with a smooth measurement side surface and a continuous semicylindrical back side wall surface continuous with this. We propose a microwave moisture measuring device in which the head is installed in the flow path of the aggregate so that the measurement side surface of the head is inclined by about 120 ° with respect to the flow direction of the aggregate.

This device is effective when the protective plate forming the measurement side surface is made of ceramics.

[0010]

[Action]

 A microwave at the resonance frequency of water molecules is output from the transmitter inside the sensor, which is placed toward the measurement side where the surface is smooth, and this also reflects the reflected wave that is compared with the amount of energy that causes water in the aggregate to resonate. The measurement is performed with the receiver placed toward the measurement side surface.

A sensor installed by inclining the plane on the measurement side with respect to the flow direction of the aggregate by about 120 ° (about 30 ° with respect to the horizontal plane) is a dome of a certain size in a direction perpendicular to the plane. In addition to performing the previous measurement for the water content in the aggregate in the shape-shaped portion, it functions to secure a stable aggregate flow on the inclined measurement side plane in the aggregate flow path.

[0012]

【Example】

 FIG. 1 is a side view showing a part of an embodiment of the device of the present invention in vertical section. The flow of sand at the time of measurement (when the aggregate is taken out) near the outlet 2 of the silo 1 storing the aggregate (sand). The sensor head 3 of the microwave moisture measuring device is installed at the position.

The sensor head 3 is composed of a rod-shaped base portion with a collar and a tip portion having a substantially semicircular cross section, and a microwave transmission portion and a reception portion are built in the tip portion, and the microwave irradiation is performed. The output and receiving measurement surfaces are covered with a protective plate 4 (see perspective view of sensor head in FIG. 2) having a smooth ceramic surface.

When the sensor head 3 is installed in the silo, as shown in the front view of FIG. 3, the surface of the protective plate 4 is approximately 120 ° with respect to the sand flow direction α (approximately parallel to the horizontal plane). 30 °) It is attached with an inclination β.

In addition, in FIG. 1, 5 is a control unit, which has a function of receiving an information signal from the sensor head 3 and converting it into an output voltage value, and 6 is a display unit from the control unit 5. The moisture value (time measurement value, total amount value, etc.) is displayed according to the output voltage value of.

According to such an embodiment, the sensor head 3 penetrating into the sand stored in the silo 1 emits a microwave in which water molecules resonate from the transmitter inside the protective plate 4. . The microwave at this time reaches a distance of about 75 mm from the surface of the protective plate 4, and acts on the water inside the dome-shaped portion at this distance.

Therefore, it is possible to instantly calculate the water content inside the dome like the conventional microwave water measuring device.

Then, when the sand in the silo 1 is discharged from the outlet 2, a flow of sand occurs in the silo 1, and the sand flows on the protection plate 4 inclined by about 120 ° with respect to this flow according to the entire sand flow. Sand flows, that is, the sand on the protective plate 4 is sequentially and continuously replaced. Moreover, this sand flow has the effect of not causing turbulence in the sand flow around the head 3 as much as possible, such as not creating a cavity on the back side due to the substantially semi-cylindrical shape of the front surface of the sensor head 3. Together, they are kept stable and continuous.

Therefore, the control unit 5 capable of continuously calculating the water content of the sand in the dome-shaped area on the protective plate 4 integrates the continuous water values, and It is possible to calculate the water content in the total amount of release from the water content in proportion to the sand that has passed through the surface, that is, the sand released from the outlet 2. Moreover, it has been proved that the water content calculated and displayed by this device is within the error range of ± 0.4% as a result of actual measurement.

Since the water content is sequentially displayed on the display unit 6, it may be read and converted to adjust the water content.

[0021]

[Effect of the device]

 As described above, according to the device of the present invention, since the measuring surface of the sensor head having the built-in microwave transmitter and receiver is constituted by the smooth protective plate, it is possible to receive and transmit the microwave stably. Moreover, since this measuring surface is inclined about 120 ° with respect to the flow direction of the aggregate and the back side thereof is formed in a substantially semi-cylindrical shape, the sand flow around the head is not disturbed as much as possible, and It is possible to continuously replace sand on the measurement surface, which allows instantaneous display of the amount of water in the sand in the specified range on the measurement surface, and the water content in the sand released by conversion, etc. It is possible to know the total amount of water, and by adjusting the amount of mixing water, it is possible to obtain high quality concrete products.

Further, by constructing the measurement surface with a ceramic protective plate, it is possible to reduce the variation of the gap between the transmitter and the gap due to thermal expansion as well as the microwave injection and to stabilize the microwave frequency. It is possible to provide a sensor head that can be ejected and has excellent wear resistance and can be used for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view showing a part of a main part of an embodiment of the device of the present invention in a longitudinal section.

FIG. 2 is a perspective view showing an example of a sensor head in the device of the present invention.

FIG. 3 is a front view illustrating a mounting state of the sensor head.

[Explanation of symbols]

 1 silo 6 display part 2 outlet α direction of sand flow 3 sensor head β direction of inclination 4 protective plate 5 control plate

Claims (2)

[Scope of utility model registration request] 1. A sensor head having a microwave transmitter and a receiver built-in is formed of a smooth measurement side surface and a substantially semicylindrical back side wall surface continuous with the measurement side surface, and the measurement side surface of the head is a bone. Microwave moisture measuring device in which the head is installed in the flow path of the aggregate in a direction inclined by about 120 ° with respect to the flow direction of the aggregate. 2. The microwave moisture measuring device according to claim 1, wherein the protective plate having the measurement side surface in claim 1 is made of ceramics.