JPH0539818Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is a holding furnace for molten metal, in particular a floating heater type holding furnace equipped with an electromagnetic pump for hot water supply and configured to supply molten metal to a die-casting machine, etc. Regarding.

[Conventional technology]

In general, holding furnaces for molten metal include electric furnaces, gas furnaces, and heavy oil furnaces that also function as melting furnaces, and electric furnaces that are used only for holding molten metal. All of these furnaces are equipped with heating means for melting the raw material or maintaining the temperature of the molten metal at a predetermined temperature.

However, as the heating means mentioned above, crucible type or reverberatory furnace type have conventionally been used, but these heating means all have the following drawbacks, and improvements are desired. Ta. In other words, all of these heating methods are indirect heating methods, that is, methods that heat through the crucible or air, so firstly, the heating efficiency is extremely poor, and secondly, the atmospheric temperature inside the furnace is extremely high. It was hot. As a result, the heating means has become larger and its energy efficiency has decreased, while the growth of oxides has been abnormally promoted within the furnace, requiring frequent cleaning of the interior of the furnace.

Therefore, as a method for solving the above-mentioned difficulties, heating means as shown in FIGS. 3 to 5 have been proposed. That is, in FIGS. 3 and 4, the electromagnetic pump EMP is installed on the die casting machine M.
Three immersion electric heaters 14 are installed through the side wall 12 of the holding furnace 10 for the molten metal L supplied through the holding furnace 10.
is installed. This immersion heater 14 consists of a heater 16 and a protective tube 18. The protective tube 18 penetrates the lining 26 of the side wall 12 and the heat insulating layer 24 and is fixed to the outer frame 12 with its flange 18a. is connected to the conductor 20. That is, with this configuration, since the molten metal L is directly heated by the immersion heater 14, the heating efficiency of the immersion heater 14 is maximized, and
On the other hand, the temperature of the furnace atmosphere 28 is suppressed to a minimum. Therefore, the above-mentioned difficulties are solved. That is, the heating energy efficiency is improved and the growth of oxides in the furnace is suppressed. Note that reference symbol FV indicates a molten metal replenishment valve. That is, when the molten metal L is supplied to the die casting machine M and the molten metal L in the holding furnace 10 decreases, the replenishment valve FV is opened and the replenishment molten metal is supplied. The temperature is uniformly heated and maintained at a predetermined temperature.

FIG. 5 shows another arrangement example of the immersion heater. In this example, the immersion heater 14 is held on a support plate 30 supported on the side wall 12 of the holding furnace 10;
The lower part of the heater 14 is immersed in the molten metal L. In this case as well, substantially the same effects as those shown in FIGS. 3 and 4 described above can be achieved.

[Problem that the invention attempts to solve]

However, the above-mentioned heating method using an immersion heater poses new difficulties, and for this reason, its use is currently not widely used despite the above-mentioned remarkable effects. This has not yet been reached.

That is, in the above-mentioned heating method, when the immersion heater 14 is installed through the side wall 12 of the holding furnace 10 (see FIGS. 3 and 4), maintenance of the immersion heater 14, especially every time it is replaced, is required. holding furnace 1
It is necessary to once pump out the molten metal L inside 0, demolish a part of the side wall 12, replace the immersion heater 14, repair and dry the side wall 12, and finally refill with the molten metal L.
In this case, pumping out the molten metal L involves dangerous work, and drying the furnace wall requires a relatively long time. Next, when the immersion heater 14 is held via the support plate 30 (see FIG. 5), the immersion heater 14 can be easily removed to the outside of the holding furnace 10, so its maintenance and replacement can be easily performed. However, the molten metal L in the protective tube 18 immersed in the molten metal L and the atmosphere 2
The corrosion at the interface with the immersion heater 14 is severe, and therefore the life of the entire immersion heater 14 is extremely short, making it unsuitable for practical use.

FIG. 2 shows a heat-resistant immersion heater 14 immersed in the molten metal in a holding furnace 10 using a heat-resistant float 42.
This figure shows a conventional floating-type holding furnace, which has a structure in which the molten metal is held on the surface of the molten metal and floated on the surface of the molten metal. That is, in this holding furnace, a float 42 is formed of a predetermined heat-resistant material, and a through hole 44 for holding the immersion heater 14 is bored inside the float 42 . The immersion heater 14 has a protective tube 18 made of a predetermined heat-resistant material.
A heater 16 is housed inside the heater 16, and a conducting wire 20 is connected to the heater 16. The immersion heater 14 is inserted into the through hole 44 of the float 42 with the heat-resistant filler 46 filled therein, and the protective tube 18 is inserted into the through hole 44 of the float 42 .
It is fixed to the float 42 with the flange 18a. The float 42 is held floating on the surface of the molten metal, and a means for pulling the immersion heater 14 out of the molten metal is provided as appropriate.

In the holding furnace 10 configured in this way, the molten metal L is fed to the die-casting machine M via the electromagnetic pump EMP.
When the molten metal L in the holding furnace 10 decreases by a predetermined amount, the replenishment valve FV opens and the molten metal is replenished.
The molten metal in the holding furnace 10 containing this molten metal is
It is heated by the immersion heater 14 of the heating means 40. In this case, since the molten metal L is directly heated by the immersion heater 14, the heating energy efficiency is good. On the other hand, the temperature of the furnace atmosphere 28 is kept at a minimum, and the growth of oxides is suppressed.

However, in the holding furnace configured as described above, since the float 42 is simply held floating on the molten metal surface, the load of the molten metal on the hot water supply electromagnetic pump EMP changes when the molten metal level in the holding furnace changes. , it is difficult to quantitatively control the discharge amount. In this case, detecting the level of the molten metal with a detector and frequently replenishing the molten metal in order to maintain a constant molten metal level has the disadvantage of increasing the burden of controlling the molten metal supply.

Therefore, the purpose of the present invention is to provide a flowchart that allows easy maintenance and replacement of the heating means, as well as heating the holding furnace with high energy efficiency and without promoting the growth of oxides in the furnace. In floating heater type holding furnaces, the floating heater type can smoothly control the constant molten metal level and accurately quantitatively control the amount of hot water supplied from the holding furnace without putting any burden on controlling the supply of molten metal to the holding furnace. Our purpose is to provide a holding furnace.

[Means for solving problems]

In order to achieve the above object, the floating heater type holding furnace according to the present invention has at least one heater that is immersed in the molten metal on a heat-resistant float that is floated on the molten metal surface.
In a floating heater type holding furnace, which is configured to hold two heat-resistant immersion heaters, to arrange the float so that it can be raised and lowered via a lifting means, to have a molten metal level detector for detecting a reference set level of the molten metal level, and to keep the molten metal level at a set level by connecting the molten metal level detector to a lifting control device that controls the lifting means of the float, the inside of the furnace is divided into a molten metal pumping chamber, a molten metal storage chamber, and a molten metal supply chamber by partition walls having a communication port at the bottom, and the molten metal level detector is arranged in the molten metal pumping chamber,
The system is characterized in that a float is disposed in the molten metal storage chamber to maintain the molten metal in the holding furnace at a constant molten metal level, and further includes a molten metal supply means configured to detect the lower limit position of the float to open a supply valve provided on a molten metal supply pipe connected to the molten metal supply chamber, and to detect the upper limit position of the float to shut off the supply valve.

[Effect]

Since the molten metal in the holding furnace is directly heated by an immersion heater immersed in the molten metal, heating energy efficiency is maximized, while the atmospheric temperature in the furnace is kept to a minimum to reduce oxide formation. Growth is inhibited. Moreover, since the immersion heater can be easily taken out of the furnace by raising and lowering the float, its maintenance and replacement can be easily performed. Moreover, in this case, there is no need for the dangerous operation of pumping out the molten metal from the holding furnace. Furthermore, since the molten metal level can be maintained constant by controlling the float to rise and fall, the amount of hot water supplied can be precisely controlled quantitatively.

〔Example〕

Next, embodiments of the floating heater type holding furnace according to the present invention will be described in detail below with reference to the accompanying drawings. For convenience of explanation, the same reference numerals are given to the same components as in the conventional structure shown in FIGS. 2 to 4.

FIG. 1 shows a holding furnace equipped with heating means as a typical embodiment of the present invention. In other words, in the holding furnace of this embodiment, by arranging the float forming the heating means so that it can be raised and lowered, the molten metal level in the holding furnace can be maintained at a predetermined level, and the amount of hot water supplied to the die-casting machine can be controlled. The structure is such that quantitative control can be achieved with a simple structure and high precision.

Therefore, the holding furnace 10 has a partition wall 48 having a communication port 48a at the bottom thereof, and a molten metal pumping chamber 10.
The molten metal storage chamber 10b is divided into a molten metal storage chamber 10b, a molten metal replenishment chamber 10c, and a float or heating means 50 is disposed in the molten metal storage chamber 10b.
A hot water level detector 52 is disposed within 0a. Heating means 5
0 consists of a box-shaped float 54 and an immersion heater 14 that penetrates the bottom plate of the float in a liquid-tight manner and is attached to the top plate.
The float 54 is attached to the support plate 5 attached to the side wall 12.
It is disposed on an elevating mechanism 58 supported on a support rod 60 so as to be movable up and down.

The elevating mechanism 58 includes, for example, a pinion that meshes with a rack machined into the support rod 60 and a drive device that drives this pinion, and this drive source includes pneumatic pressure,
Hydraulic or electric energy can be used.

The hot water level detector 52 is mounted on a support plate 62 attached to the side wall 12, and the hot water level detector 52 is connected to a lifting operator 64 that controls a lifting mechanism 58 for the float 54. In this case, the lift operation device 64 is connected to the hot water level detector 52 that detects contact with and separation from the hot water level setting level La.
The elevating mechanism 58 is driven in the direction of lowering the float 54 at the time of separation, and in the direction of raising the float 54 at the time of contact.

In this embodiment, the opening/closing mechanism 68 of the replenishment valve FV is connected to the lifting/lowering operation device 64, so that the replenishment valve FV has the float 54 at the lower limit position.
When the float 54 reaches the upper limit position UL (the position shown by the solid line in the figure), it is automatically opened to replenish the molten metal, and when the float 54 reaches the upper limit position UL (the position shown by the two-dot chain line in the figure), it is automatically closed. It is configured to cut off the supply of molten metal.

Further, the extraction pipe of the hot water electromagnetic pump EMP is installed close to and below the hot water level setting level La. Furthermore, the static hot water level Lb in the discharge pipe of the electromagnetic hot water pump EMP is set to be located near the plunger sleeve of the die casting machine M.

According to the holding furnace of this embodiment having such a configuration, when the molten metal L is supplied to the die casting machine M via the molten metal electromagnetic pump EMP, the molten metal pumping chamber 1
0a, the hot water level is about to drop from the set level La, but at this time the hot water level detector 52 detects this state, and the float 54 is lowered via the lifting operation device 64 and the lifting mechanism 58. The volume of molten metal in the holding furnace 10 corresponding to the volume of the supplied molten metal is replaced by the descending float 54, and the molten metal level is maintained at the reference setting level La. On the other hand, when molten metal is replenished via the replenishment valve FV and the molten metal level in the holding furnace 10 attempts to rise above the set level La,
The float 54 rises and the hot water level reaches the reference setting level.
Maintained in La. In this way, the suction head of the electromagnetic pump EMP for hot water supply is always kept constant, so by operating the electromagnetic pump EMP normally, the amount of molten metal supplied can always be kept constant.

In addition, in the holding furnace in this example, when replacing the electromagnetic pump EMP, for example,
When the float 54 is raised, the molten metal level in the holding furnace reaches 2
Since the molten metal falls to the falling molten metal level Lc shown by the dotted chain line, the remaining molten metal in the electromagnetic pump piping path is discharged by its own weight onto the falling molten metal level Lc. Therefore, electromagnetic pump
EMP can be easily replaced. Furthermore, since the static liquid level Lb in the electromagnetic pump discharge pipe is located near the plunger sleeve of the die-casting machine, even if, for example, a change occurs in the casting cycle, the temperature of the molten metal supplied to the die-casting machine M does not vary greatly, and therefore does not have a negative effect on the casting conditions of the die casting machine M.

In addition, in the holding furnace of this embodiment, the heating energy efficiency of the heating means can be maximized, the furnace atmosphere temperature can be suppressed to a minimum, and the heating means can be easily maintained or replaced.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.
Of course, many improvements and changes can be made without departing from the spirit of the invention. for example,
The heating means used in the present invention can be applied not only to a semi-closed type holding furnace or a closed type holding furnace, but also to a ladle hot water supply type holding furnace.

[Effect of idea]

As explained above, according to the floating heater type holding furnace according to the present invention, basically the heat-resistant immersion heater immersed in the molten metal is held on the heat-resistant float floating on the surface of the molten metal to heat the molten metal. By configuring the means, the molten metal in the holding furnace is directly heated by the immersion heater, which maximizes heating energy efficiency, while also keeping the furnace atmosphere temperature to a minimum to prevent oxide growth. can be suppressed.

In particular, according to the present invention, the inside of the furnace is divided into a molten metal pumping chamber, a molten metal storage chamber, and a molten metal replenishment chamber by a partition wall having a communication port at the bottom, and a molten metal level detector is disposed in the molten metal pumping chamber. By arranging the float in the molten metal storage chamber, it is possible to properly detect the molten metal level in the pumping chamber when pumping out the molten metal. It prevents interference with the detector, and also when replenishing molten metal to the molten metal replenishment chamber.
Interference between the molten metal level detector and the float can be effectively prevented, and highly accurate constant molten metal level control can be easily achieved at all times.

The replenishment of molten metal into the molten metal replenishment chamber can also be achieved appropriately and smoothly by setting the upper and lower limit positions of the float.

Therefore, according to the present invention, it is possible to maintain the molten metal level in the holding furnace at a constant level, thereby keeping the suction head of the electromagnetic pump for hot water constant, thereby increasing the discharge amount of the electromagnetic pump, that is, the amount of hot water supplied. It is possible to easily realize mass production of cast products with stable quality through highly accurate quantitative control.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a typical embodiment of a floating heater type holding furnace according to the present invention, Fig. 2 is a sectional view showing the configuration of a conventional floating heater type holding furnace, and Fig. 3 is a conventional 4 is a sectional view showing an example of the configuration of a holding furnace for molten metal.
A line sectional view, FIG. 5 is a sectional view showing another configuration example of a conventional holding furnace for molten metal. 10... Holding furnace, 10a... Molten metal pumping chamber, 10
b... Molten metal storage chamber, 10c... Molten metal supply room, 12
... Side wall, 14 ... Immersion heater, 16 ... Heater, 18 ... Protection tube, 18a ... Flange, 20 ...
Conductive wire, 28...Furnace atmosphere, 30...Support plate, 4
0...Heating means, 42...Float, 44...Through hole, 46...Heat-resistant filling, 48...Dividing wall,
48a...Communication port, 50...Heating means, 52...
Hot water level detector, 54...Float, 56, 62...
Support plate, 58... Lifting mechanism, 60... Support rod, 6
4... Lifting operation device, 68... Opening/closing mechanism, M... Die casting machine, L... Molten metal, La... Set hot water level, Lb... Stationary hot water level, Lc... Falling hot water level, EMP... ...Solenoid pump, FV...Replenishment valve, LL...Lower limit position, UL...Upper limit position.

Claims (1)

[Claims for Utility Model Registration] At least one heat-resistant immersion heater immersed in the molten metal is held on a heat-resistant float floating on the surface of the molten metal, and the float is arranged so as to be able to rise and fall freely through a lifting means, and the molten metal A floating device is equipped with a molten metal level detector that detects the standard set level of the molten metal surface, and this molten metal level detector is connected to a lifting operation device that controls the raising and lowering means of the float to maintain the molten metal surface at the set level. In the heater-type holding furnace, the inside of the furnace is divided into a molten metal pumping chamber, a molten metal storage chamber, and a molten metal replenishment chamber by a partition wall having a communication port at the bottom, and a molten metal level detector is installed in the molten metal pumping chamber, and
A float is disposed in the molten metal storage chamber to maintain the molten metal in the holding furnace at a constant molten metal level, and a replenishment valve is provided in the hot water supply pipe that detects the lower limit position of the float and communicates with the molten metal replenishment chamber. What is claimed is: 1. A floating heater type holding furnace, comprising a molten metal replenishing means configured to open the replenishment valve and detect the upper limit position of the float to shut off the replenishment valve.