JPH0152688B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a viscometer that enables rapid and highly accurate viscosity measurement.

When measuring the viscosity of a liquid, a stick or spatula-shaped object is immersed in the liquid to be measured, then lifted into the air, and the viscosity is determined from the resistance felt in the hand and the way the liquid drips or flows. has been practiced since ancient times. However, this method is only used in special cases because it requires skill for measurement and even experienced people can only accurately measure the viscosity of a specific type of liquid in most cases. A viscometer that can obtain objective measured values is generally used, and conventional viscometers have been proposed based on the following principle.

(1) Capillary method: When the fluid to be measured is passed through a capillary of a certain size, the viscosity is determined from the pressure difference between the two ends of the capillary, the flow rate, and the density of the liquid.

(2) Falling ball method: A ball is dropped into the liquid to be measured, and the viscosity is determined from the velocity and density of the liquid when the ball reaches a certain level.

(3) Rotating type: Viscosity can be determined from the rotational speed and torque required for rotation when rotating a rod or disk in the liquid to be measured.

Among the above, the rotary type (3) is often used industrially because it is easy to perform automatic measurements and requires relatively few samples. For example, FIG. 1 shows a rotational viscometer, where 1 is the viscometer body and 2 is a container for the liquid to be measured. The viscometer main body 1 has a shaft 4 to which a rotary scale plate 3 is fixed, which can be rotated by a rotating mechanism 5 such as a motor, and a shaft 7 to which a pointer 6 is fixed is connected to the tip of the shaft 4 by a coil spring 8. ing. This shaft 7 has a disk 9 fixed to its tip, and the liquid to be measured 10 placed in the liquid to be measured 2 is
immersed inside. Further, this container 2 is configured as a double cylindrical tube, and the liquid to be measured 10 is filled inside by flowing water at a constant temperature from the outside through tubes 11, 11 into the space between each cylinder.
to keep the temperature constant.

According to this viscometer, the disk 9 is connected to the liquid 10 to be measured.
When the shaft 4 is rotated at a constant speed, the disc 7 receives a viscous resistance from the liquid 10 to be measured, and the shaft moves to a position where this viscous resistance and the control force of the coil spring 8 are balanced. 7 rotates with a relative angular displacement with respect to the axis 4. The angle of this relative angular displacement is then displayed on the scale 3 by the pointer 6, and the viscosity can be determined from this value.

However, according to this viscometer, it is necessary to fill a special container 2 with the liquid to be measured, which is a troublesome work, and it is difficult to collect the liquid to be measured that has adhered to the disk or container after the measurement is completed. There is a problem that it is difficult to measure and the liquid to be measured is wasted. In particular, when expensive gold paste is used as the liquid to be measured, the loss due to non-recovery becomes large. Furthermore, since this viscometer controls the temperature of the liquid to be measured by transferring it to a container, it takes a long time for the liquid to reach a certain temperature, resulting in poor working efficiency.

The present invention has been developed in view of the above, and its purpose is to eliminate the need to transfer the liquid to be measured into a special container and to control the temperature, thereby quickly, easily, and highly accurately measuring the viscosity. It is an object of the present invention to provide a viscometer that can perform measurements and eliminate waste of liquid to be measured.

In order to achieve such an object, the present invention has a measuring rod that can be immersed in a liquid to be measured for a certain length and can be pulled up, and means for detecting the force and time when pulling up this measuring rod; The present invention is characterized by being provided with a circuit that calculates the total volume based on these detected values, and a display section that displays the viscosity based on the output of this circuit.

The present invention will be explained in detail below.

First, if we consider the manual viscosity measurement described above, when a rod is immersed in the liquid to be measured for a certain length d and pulled up at a speed v(t) that is an arbitrary function of time t. , the rod-like body receives a downward force F(t) due to viscosity from the liquid (however,
Assume that the force due to gravity can be ignored). It can be seen from equation (1) that the impulse A applied to the rod-shaped body during the time t ₁ until it is completely pulled up is proportional only to the viscosity η, regardless of the speed v(t). k is a constant.

A=∫ ^t1 ₀ F(t)dt=∫ ^t1 ₀ kηv(t) {d−∫ ^t ₀ v(
t) dt} dt = kηd∫ ^t1 ₀ v(t) dt−kη∫ ^t1 ₀ v(t) {∫ ^t ₀ v
(t)dt}dt = kηd ² −1/2kηd ² = 1/2kηd ² …(1) On the other hand, viscosity is a function of temperature, and if the liquid to be measured is like the paste mentioned above, the absolute temperature TK The viscosity η _T at 20° C. is expressed by equation (2), where η ₂₀ is the viscosity at 20° C., and B is a constant.

η _T = η ₂₀ e ^B/T …(2) From equations (1) and (2), it can be seen that the rod-shaped body is d
Measure the temperature by dipping the rod for a certain length, then pull it up (if you know the total area from the start of pulling until the tip of the rod leaves the liquid surface, η ₂₀
It turns out that it is possible to find

FIG. 2 shows an embodiment of the present invention constructed based on the above principle. In the figure, reference numeral 12 denotes a measuring rod made of, for example, a metal material in the shape of a rod, and an index 13 is formed on the outer periphery at a predetermined dimensional position from its tip.
It is used as a mark when immersing into the liquid to be measured. The measuring rod 12 has its tip closed and has a temperature sensor 14 such as a thermistor installed therein to detect the temperature of the liquid to be measured. On the other hand, the measuring rod 1
2 has its upper end base inserted into the cylindrical handle portion 15, and is supported by a plurality of beams 16 arranged radially on the inner surface of the handle portion. A strain gauge 17 is attached to at least one of these beams 16 by pasting or the like, and when a relative force is applied between the handle portion 15 and the measuring rod 12, the strain gauge 17 is attached as the beam 16 is strained. An output is generated at 17 and this force can be detected.

On the other hand, an amplification calculator 1 is provided in the handle portion 15.
Based on the output of the strain gauge 17, the calculator 18 determines the point at which the pulling force suddenly increases when the measuring rod 12 starts to be pulled up, and the point at which the small pulse force that appears at the end of pulling is generated. A time detecting means 19 is provided which detects the time required to lift the measuring rod 12 by detecting the difference between these points. Further, the arithmetic unit 18 is provided with an arithmetic circuit 20 that integrates the force detected by the strain gauge 17 with respect to time and calculates the total product up to the point of completion of lifting. The detected value of the temperature sensor 14 is inputted to an arithmetic circuit 20 which is constituted by an integral circuit. Further, an analog or digital display 21 is installed inside the handle portion 15, and receives the output of the arithmetic circuit 20 to display the viscosity. In the figure, 22 is a power switch.

Next, a method of measuring viscosity using the viscometer having the above configuration will be explained. First, an operator holds the handle portion 15 and immerses the measuring rod 12 into the liquid to be measured up to the position of the indicator 13. In this case, the immersion time is preferably 30 seconds or more, and the liquid to be measured can remain in its original container, and there is no need to transfer it to a special container. Then, after turning on the power switch 22, if you hold the handle part 15 and pull up the measuring stick 12 at a desired speed, the viscosity of the liquid to be measured will be displayed on the display 21 almost at the same time as the lifting is completed, and the measurement can be started immediately. finish.

Here, the internal action of the viscometer is such that as the measuring rod 12 is pulled up, the handle portion 15 and the measuring rod 12
The force that depends on the viscosity of the liquid to be measured is detected between the As shown in FIG. 3, this force varies depending on the viscosity of the liquid and the pulling speed, and also changes momentarily during pulling. In the same figure, a shows a case in which the measuring rod is pulled up from a low-viscosity liquid at high speed, b shows a case in which the measuring stick is pulled up at a low speed from a high-viscosity liquid, and c shows a case in which the measuring stick is pulled up at a high speed from the same high-viscosity liquid. are shown respectively. All of these begin to be pulled up at time t=0 and end at times ta, tb, and tc, respectively. At the end of each case, small pulse forces Pa, Pb, and Pc are generated due to the surface tension of the liquid surface, and by detecting these small pulse forces Pa, Pb, and Pc, the completion time of lifting can be determined. The total area applied to the measuring rod 12 by this time (integral value of force x time, i.e. area of the triangle in Figure 3)
is determined by the arithmetic circuit 20. By substituting this total volume value into equation (1), the viscosity can be calculated, and this can be displayed on the display 21. At this time, the temperature of the liquid at that time is detected by the temperature sensor 14, and the viscosity at 20° C. can be determined by substituting the absolute temperature and the above-mentioned measured viscosity into equation (2).

As mentioned above, in any measurement, after a small pulse force is generated, the force applied to the measuring rod becomes almost zero, so in any measurement, a time td that is sufficient to complete the lifting must be set in advance. This may be regarded as the lifting completion time and the total volume up to that point may be calculated. in this case,
The means for detecting the completion of lifting is configured as a type of constant circuit within the arithmetic unit 18.

Here, the means for detecting the force applied to the measuring rod 12 may be configured using, for example, a tension gauge or a pressure sensor, regardless of the combination of the beam 16 and strain gauge 17 described above. Furthermore, it goes without saying that various modifications can be made to the shape of the handle portion and the connection structure between the handle portion and the measuring rod.

As described above, the viscometer of the present invention has a measuring rod that can be immersed in a liquid to be measured for a certain length and then pulled up, and the viscosity is measured by calculating the total volume when the measuring rod is pulled up. As a result, there is no need to transfer the liquid to be measured into a special container, and the measurement can be performed while it is in the original container, making it easier for the operator and eliminating the need to waste liquid. . In addition, since there is no need to control the temperature of the liquid and the pulling rate can be set arbitrarily, the measurement work can be simplified and the measurement time can be shortened.Furthermore, since the viscosity is determined from the total volume, it is possible to measure high viscosity. This has the advantage of being able to perform the following tasks.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a conventional rotational viscometer, FIG. 2 is a broken perspective view of the viscometer of the present invention, and FIG. 3 is a time characteristic diagram of lifting force for explaining the total volume. DESCRIPTION OF SYMBOLS 12... Measuring rod, 13... Index, 14... Temperature sensor, 15... Handle part, 16... Beam, 17... Strain sensor, 18... Arithmetic unit, 19... Time detection means, 20...
Arithmetic circuit, 21...display device.

Claims (1)

[Claims] 1. A measuring rod that can be immersed in a liquid to be measured for a certain length and pulled up, a handle part that supports this measuring rod, and a force that can be used to pull up the measuring rod immersed in the liquid between the measuring rod and the handle part. means for detecting the time from the start to the end of the pulling based on a change in the pulling force; and means for detecting the time from the start to the end of the pulling based on a change in the pulling force, and a means for detecting the time from the start to the end of the lifting based on a change in the lifting force, and a means for detecting the time from the start to the end of the lifting based on a change in the lifting force, and a means for detecting the lifting of the measuring rod by integrating the lifting force over the lifting time. A viscometer comprising: a circuit for calculating the total volume required for the calculation; and a display section for displaying the viscosity obtained from the calculation by the calculation circuit.