JPH0216838Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for switching the suction capacity of a molten metal stirring device.

(Prior Art) When melting metals such as aluminum, copper, zinc, etc., the molten metal is stirred in order to reduce the amount of oxidation generated and shorten the melting time.

FIG. 3 is a block diagram of a known mechanical stirring device. In the figure, a refractory intermediate body 3 with a nozzle 2 installed therein is provided at the bottom of a melting furnace 1, and a pump cylinder 4 whose inner wall is lined with a refractory material is provided on the intermediate body 3.
Install. The pump cylinder 4 communicates with the bottom of the melting furnace 1 through a nozzle 2, and the head of the pump cylinder has a ventilation pipe 8 with an automatic switching valve 5 between outside air and negative pressure, a cyclone 6, a filter 7, etc. It is connected to the vacuum blower 9 by. The vacuum blower 9 is operated by a motor 10 to suck and introduce molten metal into the pump cylinder 4 under vacuum pressure, and after a certain period of time has passed, the automatic switching valve 5 is switched to introduce outside air into the pump cylinder 4. Since the vacuum suction force was removed and outside air was introduced, the molten metal sucked up into the pump cylinder 4 automatically returned to the melting furnace 1, and convection occurred in the molten metal accumulated in the furnace, stirring the inside of the melting furnace 1. be done.

(Problem to be Solved by the Invention) When the cold material has finished melting, the molten metal is taken out of the melting furnace 1 and a new cold material is introduced into the melting furnace 1. The cold material is melted by the heating of the above-mentioned furnace, and the nozzle 2
Start stirring when the level of the opening is exceeded. By being exposed to the molten metal discharged from the pump cylinder 4, melting is significantly promoted.

However, when starting the stirring operation using the pump cylinder 4, if there is not enough molten metal in the melting furnace 1 at the opening of the nozzle 2,
If care is not taken to reduce the amount of suction by the vacuum blower 9, other air in the molten metal will be drawn into the pump cylinder 4.
It will be inhaled. When air is sucked in, the sucked molten metal is oxidized, scatters, adheres to the top of the pump cylinder, and solidifies. In other words, when starting the stirring operation after charging the cold material into the melting furnace 1, the operator is required to pay careful attention to the operation.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an automatic switching valve between outside air and negative pressure as a means for sucking molten metal from a melting furnace into a pump cylinder through a nozzle and discharging it. A timer is interposed between the head of the pump cylinder and the vacuum blower, and is started by closing the vacuum blower operating switch, and times up after a set time. A switching means is provided for switching from the side to the negative pressure side for the set time, and when the cold material is introduced, the set time is set to a shorter time than during normal melting.

(Function) With the above configuration, when the stirring operation is restarted, the switching valve between negative pressure and outside air is operated for a certain period of time after restarting, and the switching valve between negative pressure and outside air is connected to the negative pressure side for a shorter period of time than the normal communication time. Since the molten metal in the melting furnace is sucked up into the pump cylinder and then discharged, even if the level of the molten metal in the melting furnace is only slightly higher than the nozzle opening surface, the suction operation will continue. Sometimes outside air other than the molten metal is sucked up.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings. FIG. 1 is an electrical circuit diagram of the stirring operation after the cold material is introduced into the melting furnace. In the figure, between the output terminal 3 and the (-) terminal 2 of the operating switch Sw of the vacuum blower 9, which is connected to the (+) terminal of the DC power supply,
_The electromagnetic coil 5a of the automatic switching valve 5 between outside air and negative pressure shown in FIG _.
after activation, t ₁ hour delay t ₂ hours off) and contact T ₄
−1 (t′ ₁ hour delay t ₂ hours off after starting timer T ₄ )
are connected to the series circuit. Furthermore, a series circuit of timer T ₁ and contact T ₂ -1 (t ₁ hour delay t ₂ hours off after timer T ₂ starts) and timer T ₂ and contact T ₁ - 2
A parallel circuit with a series circuit (t ₁ hour delay t ₂ hours on after starting timer T ₁ ) and contact T ₃ -1 (timer T ₃
In addition, a series circuit is connected between terminals 3 and 2 with a ₁ hour delay (T ₁ hour off) after activation of the timer.
T ₃ is also connected. Additionally, timer T ₄ and contact T ₅ −
1 (t′ ₁ hour delay after starting timer T ₅ , time t ₂ off,
However, the series circuit of t' ₁ > t ₂ ) and the timer 15 and contact
A parallel circuit with a series circuit of T ₄ −2 (on for t ₂ hours with a delay of t′ ₁ hour after activation of timer T ₄ ) and a contact T ₃ −2
A series circuit with (time _T1 delay time _T1 on after activation of timer _T3 ) is also connected between terminals 3 and 2.

The operating characteristics of the timers _T1 to _T5 are as shown in the time chart of FIG.

Next, the operation of this embodiment will be explained with reference to FIGS. 1 and 2. First, switch for operating vacuum blower 9.
Turn on SW. The timer T ₃ is started for a time T ₁ by this ON operation of the switch Sw, and during this period, the contact T ₃ -1 is closed, and since the contact T ₂ -1 is also closed, the timer T ₁ is started. to start. By starting the timer _T1 , the contact _T1-1 is closed for an hour _t1 , and since the timer _T4 is not started, the contact _T4-1 is also in the closed state, and the electromagnetic coil of the automatic switching valve 5 5a is energized by a power source, and communicates the pump cylinder 4 with the vacuum blower 9 side (negative pressure side) for a time _t1 , so that the pump cylinder 4 sucks the molten metal from the melting furnace 1. This time t ₁ is shorter than the predetermined time t' ₁ (the communication time when the cold material in the melting furnace 1 is melted and the molten metal level is sufficiently higher than the opening area of the nozzle 2) (t ₁ <
t' ₁ ) By selecting the pump cylinder 4
The molten metal does not inhale other outside air.

After time t ₁ has elapsed, contact T ₁ -2 closes and the contact
Since T ₃ -1 is closed for time T ₁ (see FIG. 2), timer T ₂ is closed. This closure causes contact T ₂ -1 to open and timer T ₁ to stop operating. Further, when the time t ₁ has elapsed, the contact T ₁ -1 is opened and the electromagnetic coil 5a of the automatic switching valve 5 is deenergized. As a result of this deenergization, the electromagnetic coil 5a is automatically switched to communicate the pump cylinder 4 with the outside air for a time _t2 , during which time the molten metal drawn into the pump cylinder is discharged to the melting furnace 1, and the molten metal is discharged into the melting furnace 1 for the time t2. After t ₂ has elapsed, contact T ₂ -1 is closed, and following the above-mentioned process, the automatic switching valve 5 switches the pump cylinder 4 to the negative pressure side for a predetermined time t ₁ hour, and then t Switch to outside air for ₂ hours. This switching operation is repeated during the activation time _T1 of the timer _T3 .

After the above time T ₁ has elapsed, timer T ₄ is switched to timer T _1.
The same operation as above is performed to energize the electromagnetic coil of the automatic switching valve 5. Therefore, the pump cylinder 4 is switched to the negative pressure side for the predetermined time _t'1 , that is, for a time _t'1 that is longer than the suction time _t1 of the pump cylinder 4 immediately after the coolant is introduced. After this switching, the electromagnetic coil of the automatic switching valve 5 is deenergized, the pump cylinder 4 is communicated with the outside air, and normal stirring work is performed.

Note that although timers _T1 to _T5 are used in this embodiment, the present invention is not limited to this, and a programmable sequencer or the like may be used.

(Effect of the invention) As explained above, in the present invention, when starting the stirring work after charging the cold material into the melting furnace, the pump cylinder that sucks in and discharges the molten metal from the melting furnace is connected to the negative pressure side and the outside air side. Immediately after the switching operation of the automatic switching valve is started, the switching operation is repeated with an amount smaller than the normal suction amount, and the refrigerant near the nozzle discharge port is melted. Therefore, even at the start of the stirring operation, air is not sucked into the pump cylinder at the same time as the molten metal. Therefore, the molten metal sucked into the pump cylinder does not adhere to the upper part of the pump cylinder and solidify, thereby promoting the stirring effect.

[Brief explanation of drawings]

FIG. 1 shows an electric circuit diagram of an embodiment of the present invention, FIG. 2 shows a time chart of switching operation of an automatic switching valve, and FIG. 3 shows a configuration diagram of a conventional stirring device. 1... Melting furnace, 2... Nozzle, 3... Pump cylinder, 5... Automatic switching valve, 5a... Electromagnetic coil, 9... Vacuum blower, 10... Motor, T ₁ ,
T ₂ , T ₃ , T ₄ , T ₅ ... timer.

Claims (1)

[Scope of utility model registration request] In the molten metal stirring device, an automatic switching valve between outside air and negative pressure is interposed between the head of the pump cylinder and the vacuum blower as a means for sucking the molten metal from the melting furnace into the pump cylinder through a nozzle and discharging it. , a timer that starts when the vacuum blower operating switch is closed and times up after a set time; and a switching means that switches the automatic switching valve from the outside air side to the negative pressure side for the set time when the timer starts. A switching device for the suction capacity of a molten metal stirring device, characterized in that the set time is set to a shorter time than during normal melting when the cold material is introduced.