JPH0257664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dissolution confirmation method for confirming whether dissolution has been completed.

[Prior Art] In a power cable manufacturing process, a crosslinking agent and an anti-aging agent are mixed in a certain ratio with an insulating material such as polyethylene to crosslink the insulating material. The crosslinking agent and anti-aging agent are supplied to the insulating material by uniformly mixing the insulating material, the cross-linking agent, and the anti-aging agent in an extruder. in this case,
For example, dicumyl peroxide used as a crosslinking agent has a melting point of about 40°C. Therefore, if the heating source such as the melting/mixing tank is stopped when the line is stopped, the solution inside will solidify at room temperature. For re-melting, a heating source was activated, the worker controlled the material until it was completely melted, and after confirming that the material had been re-melted, the material was fed to the extruder.

[Problems to be solved by the invention] Re-dissolution time varies depending on the room temperature and the initial temperature of the solidified mixture itself, and there is no automatic method for confirming the dissolution, so it is necessary to manage and confirm it manually. method was adopted.

An object of the present invention is to provide a dissolution confirmation method that can automatically confirm the completion of dissolution.

[Means for Solving the Problems] To explain the means of the present invention to achieve the above object, the present invention detects the temperature of the coagulated substance or its solution while heating and melting the coagulated substance, In the dissolution confirmation method when melting the coagulated material, the heating is stopped when the temperature reaches a set temperature, and the heating is restarted when the temperature decreases from the set temperature as the coagulated material is melted. The heating stop time is measured each time the heating is stopped, and when the heating stop time reaches a preset time, it is determined that the dissolution is complete.

[Operation of the invention] In the present invention, when melting is performed while adjusting the temperature by turning the heating source on and off, as the melting progresses, the heating stop time after heating reaches the set temperature becomes longer. When the heating stop time exceeds a predetermined time, it is determined that the melting is complete.

[Examples] Examples of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows an example in which the present invention is applied to an apparatus for dissolving crosslinking agents and anti-aging agents. In this melting device, a heating jacket 2 as a heating means is attached to the outer periphery of a melting container 1, and a heating medium such as hot water at a constant temperature is supplied to the bottom of the heating jacket 2 by opening a control valve 4 of a pipe 3. The heating medium that is supplied heats the coagulated material 5 or its solution 5A in the container 1, and is discharged from the piping 6 at the upper part of the heating jacket 2. A temperature sensor 7 such as a thermocouple is inserted into the container 1 to measure the temperature of the coagulated material 5 or its solution 5A and send a temperature signal to a proportional control type temperature controller 8. The temperature regulator 8 includes a timer 9, which sends an open signal to the control valve 4 to continue heating while the temperature signal is lower than the set temperature, and sends a close signal to the control valve 4 when the temperature exceeds the set temperature.
Close the timer 9 and set the heating stop (hot water supply stop) time.
It is now being measured by A liquid supply pipe 10 is connected to the bottom of the container 1, and the solution 5A is supplied to an extruder (not shown) by driving a pump 11. In addition, 12 is a hopper that supplies a crosslinking agent 13 via a valve 14, and 15 is a hopper that supplies an anti-aging agent 16 to a valve 1.
A hopper is supplied through 7, and 18 is a stirrer.

Next, an example of a method for confirming dissolution using the above-mentioned apparatus will be explained with reference to FIG. A cross-linking agent 13 and an anti-aging agent 16 are put into a container 1 at a certain ratio,
This is heated with a heating medium supplied into the heating jacket 2 to obtain a solution 5A, which is pumped out by a pump 11 and supplied to the extruder at a constant ratio.

After stopping the line, the container 1 is heated to below the melting temperature of the crosslinking agent.
When the container inside descends, coagulation begins and a coagulum 5 is formed, and the entire solution 5A in the container 1 becomes a coagulum 5.
becomes.

When remelting this coagulated material 5, the set temperature of the temperature controller 8 is set to a certain constant temperature _T2 which is higher than the melting temperature _T1 of the coagulated material 5, as shown in FIG. In this state, the control valve 4 is opened, a heating medium is supplied to the heating jacket 2, and the coagulated material 5 is heated. When the heating time elapses and the temperature of the solution 5A in the container 1 reaches a certain temperature T3 close to the set temperature _T2 at time A, the temperature regulator ₈ starts the temperature adjustment operation, and the heating medium on supply of,
Off control begins. That is, the temperature of the solution 5A is detected by the temperature sensor 7, and it is determined whether the temperature _T2 of the temperature regulator 8 has been reached. When the set temperature _T2 has not been reached, the control valve 4 is opened in response to a signal from the temperature regulator 8, and the heating medium is supplied to the heating jacket 2. When the set temperature _T2 is reached, the control valve 4 is closed and the timer 9 is simultaneously started to measure time. When the supply of the heating medium is stopped, the temperature of the melting liquid 5A decreases below the set temperature _T2 as the solidified material 5 continues to melt, so the temperature regulator 8 closes the control valve 4 again.
sends a signal to start supplying the heating medium. The timer 9 measures the time during which the heating medium supply is stopped, that is, the heating is stopped, from when the control valve 4 closes to when the control valve 4 opens again, and if the predetermined time has not been reached, it is determined that melting has not yet been completed. Then, the temperature adjustment control described above is repeated. Near point A when temperature adjustment is started, the heating time when the heat source is on is long and the heating stop time when the heat source is off is short. In such a state, the coagulated material 5 first melts from near the wall of the container 1, the temperature of the resulting solution 5A rises, and the remaining coagulated material 5 melts to lower the temperature of the dissolved solution 5A. Therefore, the process continues at a constant temperature until the solidified material 5 reaches about 1/3. At point B, when the coagulated material 5 is almost gone, the time during which the heat source is turned off becomes longer. When the solidified material 5 reaches the point C when it is completely liquefied, the heat source is turned on only occasionally to compensate for the temperature drop due to heat radiation. Therefore, the time t during which the heat source is turned off becomes gradually longer as t ₁ <t ₂ <t ₃ . The timer 9 measures the time when the heat source is turned off each time.
When the heating stop time for a certain time reaches a preset time, it is determined that the melting is completed. After the dissolution is completed, the stirrer 18 is turned, the pump 11 is driven, and the solution is supplied to the extruder.

Note that the container 1 can also be heated with an electric heater.

In the case of dissolving a crosslinking agent or an anti-aging agent, the set temperature T ₂ is higher than the melting point of the crosslinking agent and lower than a temperature at which decomposition of the crosslinking agent does not occur.

There is an idea that melting is completed when the set temperature of the temperature controller 8 is reached, but if a temperature sensor (e.g.
The error of the IC thermocouple (IC thermocouple) is approximately ±3°, and the error of the temperature controller 8 is also added, so even if the set temperature is reached, it may actually be in a semi-solid solution state, and complete dissolution cannot be confirmed.

[Effects of the Invention] As explained above, in the dissolution confirmation method according to the present invention, the heating stop time using the temperature controller is measured each time, and when the heating stop time for a certain time reaches a preset time, the dissolution is completed. Therefore, it is possible to automate the dissolution determination. Further, according to the present invention, it is possible to determine whether dissolution is complete without being influenced by external conditions.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a melting apparatus for carrying out the method of the present invention, and Fig. 2 is an explanatory diagram showing the relationship between the temperature rise characteristics of melting, the ON/OFF control state of the heat source, and the state of melting of the solidified material. It is. 1... Melting container, 2... Heating jacket, 4...
...Control valve, 5...Coagulate, 5A...Dissolution liquid, 7...Temperature sensor, 8...Temperature regulator, 9
……timer.

Claims (1)

[Claims] 1. Detect the temperature of the coagulated substance or its solution while heating and dissolving the coagulated substance, stop heating when the detected temperature reaches a set temperature, and as the coagulated substance melts, the detected temperature decreases from the set temperature. In the dissolution confirmation method when dissolving the coagulated material by repeating the step of restarting heating when the temperature decreases, the heating stop time is measured each time the heating is stopped, and when the heating stop time reaches a preset time, A dissolution confirmation method characterized by determining that dissolution is complete.