JPH0943168A - Desk moisture meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and rapidly measure the surface moisture ratio of sand on a desk. SOLUTION: A sample vessel container 3 for containing a sample vessel 2 is formed at a box-like body 1. A sample vessel elevation box 4 for containing and elevating the vessel 2 is contained in the container 3. The box 4 has sensor contact means formed of a gear unit 5, an elevation box elevating shaft 6 and a motor 7. Contact pressure regulating means 11 formed of a limit switch 9 and a switch dog 10 is provided at the unit 5 and the shaft 6. A moisture sensor 14 formed of an antenna element as one of the equilibrating condition element of a high frequency bridge 15 is disposed at the upper site of the container 3. Further, a desk control panel for operating the units, calculating and outputting a surface moisture ratio by the voltage signal of the sensor 14 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture meter for measuring the surface water content of sand used in the production of ready-mixed concrete, and more particularly to a tabletop moisture meter which can be easily measured on a desk.

[0002]

2. Description of the Related Art When producing ready-mixed concrete at a ready-mixed concrete manufacturing plant or a secondary product manufacturing plant, concrete materials such as sand, gravel, cement, water, and an admixture are kneaded and mixed at a certain ratio. It is known that the ratio of the amount of water to the amount of cement has an important effect on the strength of concrete. Therefore, when weighing water according to the composition of the concrete to be produced, it is necessary to consider the surface water of the aggregate attached to the surface of sand, gravel, or the like.

[0003] In particular, the surface water of sand has a great influence,
As a method for measuring the amount of surface water of the sand, JIS has JIS A1111 “Test method for surface water content of fine aggregate”, and the test room of each factory has a “Test method for surface water content of fine aggregate”. Based on the surface water, the surface water is measured to grasp the amount of the surface water.

[0004]

However, the above-mentioned JIS A1111 "Method for testing surface water content of fine aggregate"
Has the disadvantage that it takes time to perform weight measurement and volume measurement manually using an experimental instrument such as a pycnometer or Chapman flask, and it does not meet the cycle time of ready-mixed concrete production. In addition, it is difficult to maintain a predetermined measurement accuracy unless it is done by a skilled laboratory staff.

In view of the above points, an object of the present invention is to provide a tabletop moisture meter capable of easily measuring the surface water content of sand by anyone on a desk in a short time.

[0006]

In order to achieve the above-mentioned object, the present invention provides a sample container for containing a sample sand sample, and U
A moisture sensor consisting of an antenna element connected to a high-frequency bridge for the HF (ultra-high frequency) band as one of its parallel condition elements, and the sand surface in the sample container and the tip of the moisture sensor are brought into close contact with each other. Sensor abutting means for
Contact pressure adjusting means for adjusting the sensor contact pressure at the time of contact with the moisture sensor to a predetermined value, and a tabletop operation panel for operating the sensor contact means and calculating and outputting moisture data from a voltage signal detected by the moisture sensor. It is characterized by being configured by and.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of a desk moisture meter according to the present invention, first, a predetermined amount of sample sand is put in a sample container and set in a desk moisture meter, and a sensor contact means is operated by operating a desk operation panel. When is driven, the tip of the moisture sensor and the surface of the sample sand of the sample container come into close contact with each other. At this time, the contact pressure adjusting means operates to automatically stop the driving of the sensor contact means at the point where the contact pressure between the sensor and the sample sand reaches a predetermined value. In this state, the voltage signal detected by the moisture sensor is taken into the desktop operation panel, and the desktop operation panel calculates and outputs the surface water ratio of the sample sand from the captured voltage signal. In this way, the surface water content of the sand can be automatically measured simply by putting the sample sand into the sample container and setting it in the moisture meter, so that anyone can easily measure the surface water content with high accuracy on a desk.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment based on the embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a main body of a tabletop moisture meter.
Has a box shape, and a central upper part thereof is recessed to a predetermined depth to form a sample container storage portion 3 for storing a sample container 2 containing sample sand.

Inside the sample container storage section 3, the sample container 2
A sample container elevating box 4 for accommodating and storing the sample container and moving up and down along the wall surface of the sample container storage part 3. Further, a gear unit 5 in which a helical gear is combined is disposed below the sample container storage part 3, and the gear unit 5 is provided with an elevating / lowering box elevating / lowering shaft 6 which moves up and down from the gear unit 5 by the rotation of the helical gear to elevate / lower the sample container elevating / lowering box 4.
Further, the gear unit 5 is provided with a motor 7 for rotating the helical gear in the forward and reverse directions to form a sensor contact means 8.

A limit switch 9 is attached below the gear unit 5 and an elevator box elevator shaft 6 is provided.
Contact the limit switch 9
The switch dog 10 for operating the
A contact pressure adjusting means 11 is movably fitted in the vertical direction to adjust the sensor contact pressure to a predetermined value.

A pair of support columns 12 are erected on the upper peripheral edge of the sample container storage section 3 so as to face each other, and the horizontal member 1 is provided between the support columns 12.
A water sensor 14 to be described later is attached near the center of the horizontal member 13 such that the tip of the water sensor 14 faces the lower sample container storage portion 3.

Next, the moisture sensor 14 will be described in detail. As shown in FIG.
This is an application of a high frequency bridge 15 operating in the UHF (ultra high frequency) band of z to several hundred MHz, and the high frequency bridge 15 has a high frequency resistor 17 connected on the left side of a balancing high frequency variable resistor 16 as a boundary. An antenna element 18 for the UHF band, which serves as a sensor unit, is connected to the right side via a coaxial cable 19 as one of parallel condition elements of the bridge.

Then, the variable resistor 16 and the respective connection circuits of the high frequency resistor 17 and the antenna element 18 are connected by a balanced state detection circuit 19, and the balanced state detection circuit 19 is balanced with the detection diode 20. The capacitor 21 is connected in series. Further, a sensor output circuit is provided by branching the connection circuit of the detection diode 20 and the balance capacitor 21, and a choke coil 23 and a detection load resistor 24 are connected in series to the sensor output circuit 22. Sensor output terminals 2 are provided on both sides of the detection load resistor 24.
5, and a capacitor 26 in parallel with the detection load resistor 24.
Have been inserted. Further, a UHF band high frequency power source 27 is connected to the balancing high frequency variable resistor 16 at the power source section of the high frequency bridge 15.

Reference numeral 28 is a desktop operation panel, which is equipped with a microcomputer and is used as a keyboard 29 for inputting various data.
And a display device 30 and a printer 31 for outputting various data. The tabletop operation panel 28 receives a voltage signal from the moisture sensor 14. At the same time, the control line of the limit switch 9 is connected.

Thus, when measuring the surface water content of the sample sand sampled, the sample container 2 is filled with the sample sand to the edge and the surface is leveled. The sample container 2 is stored in a sample container storage portion 3 formed near the center of the main body 1 so that the surface of the sample sand faces the tip of the upper moisture sensor 14.

Next, the operation switch of the tabletop operation panel 28 is operated to drive the motor 7 to raise the elevating box raising / lowering shaft 6 to raise the sample container raising / lowering box 4. When the sample container elevating box 4 rises and the surface of the sample sand of the sample container 2 comes into contact with the tip of the moisture sensor 14, and the switch dog 10 of the elevating box elevating shaft 6 comes into contact with the limit switch 9, the motor 7
Stop driving. At this time, the position of the switch dog 10 with respect to the limit switch 9 is preliminarily tested and adjusted so that the contact pressure between the sample sand and the moisture sensor 14 becomes a predetermined value.

When the raising of the sample container elevating box 4 is stopped by the operation of the limit switch 9, the measurement of the surface water ratio of the sample sand is started. At this time, the antenna element 1 of the moisture sensor 14
When 8 comes into contact with the sample sand, the impedance of the antenna element 18 changes due to the influence of the dielectric constant of the water adhering to the surface of the sand, the equilibrium state of the high frequency bridge 15 is broken, and a current flows in the equilibrium state detection circuit 19. A voltage appears at the sensor output terminal 25. This voltage is taken in as a sensor output to the desktop operation panel 28, and the surface water rate of sand is calculated according to the magnitude of the output voltage. Then, the surface water rate calculated is output to the display device 30 and the printer 31.

When the measurement of the surface water ratio of the sample sand is completed, the operation switch of the tabletop operation panel 28 is again operated to reverse the motor 7, the sample container elevating box 4 is lowered, and the inner sample container 2 is taken out. Prepare for the next measurement.

In this embodiment, as the contact pressure adjusting means, the method of restricting the stop position of the sample container with respect to the moisture sensor by the combination of the limit switch and the switch dog has been described as an example. In addition to this, various methods such as a method of directly detecting the contact pressure by a pressure sensor and a method of measuring the load current of the motor for driving the contact means can be considered, and it may be appropriately adopted according to the cost and the grade of the apparatus. .

[0021]

As described above, in the tabletop moisture meter according to the present invention, the sample container 2, the antenna element 18 which is one of the equilibrium condition elements of the high frequency bridge 15, the sample sand and the water content of the sample container 2 are provided. A sensor contact means 8 for contacting the tip of the sensor 14, a contact pressure adjusting means for adjusting the contact pressure of the moisture sensor 14 with respect to the sample sand, and a tabletop for operating these devices and inputting / outputting various data. Since the operation panel 28 is used, the apparatus can be made compact so as to be suitable for desk-top measurement, and the operation is simple and anyone can accurately measure the surface water ratio of sand.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a desk moisture meter of the present invention.

FIG. 2 is a circuit diagram showing a basic configuration of a moisture sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Desktop moisture meter main body 2 ... Sample container 8 ... Sensor contact means 11 ... Contact pressure adjusting means 14 ... Moisture sensor 28 ... Desktop operation panel

Claims (1)

[Claims] 1. A sample container for containing the collected sample sand, and UH
A moisture sensor consisting of an antenna element connected to the high frequency bridge for the F (ultra high frequency) band as one of its parallel condition elements, and the sand surface in the sample container and the tip of the moisture sensor are brought close to each other and brought into contact with each other. Sensor contacting means, contact pressure adjusting means for adjusting the sensor contacting pressure at the time of contacting the moisture sensor to a predetermined value, and moisture data from the voltage signal detected by the moisture sensor while operating the sensor contacting means. A tabletop moisture meter characterized by being configured with a tabletop operation panel for calculating and outputting.