JPH0339237B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal ingot melting method and apparatus, and in particular, in a cylindrical melting chamber provided in a vertical direction,
The present invention relates to a method of charging and melting a laminated block formed by stacking a plurality of predetermined metal ingots, and an apparatus therefor.

2. Description of the Related Art Vertical furnaces, such as so-called tower melters, have been known as metal ingot melting apparatuses having a vertically extending melting chamber. and,
Such melting equipment is "Al-Aru", No. 27-32
Page (March 1982 issue), "MODERN METALS",
As disclosed in Vol. 38, No. 11, p. 76 (1982), etc., the furnace generally has a cylindrical furnace body installed in the vertical direction, and the furnace body is installed at the upper opening of the furnace body. When the furnace lid is opened, laminated blocks of metal ingots stacked in multiple stages are loaded from a predetermined charging machine, and the laminated blocks loaded into the furnace are While gradually descending inside the body, it is preheated, and is further melted by heating by a burner installed at the bottom of the furnace body, and is then stored in a holding chamber connected to the bottom of the furnace body. ing.

In other words, in a vertically erected furnace body, the laminated blocks introduced from above are gradually lowered as the lower laminated blocks introduced first are sequentially heated and melted by the burner. During the descent, the laminated block is preheated by the burner exhaust gas flowing upward in the furnace body, so that when it reaches the lower part of the furnace body, it is in a semi-molten state. Therefore, it can be easily melted by the lower burner.

However, in such a melting device,
When simply charging metal ingots in the form of laminated blocks stacked in multiple tiers through the upper opening of a vertically installed furnace body,
Such laminated blocks often get caught in the middle of the furnace body and become suspended on a shelf (suspended in mid-air), and this suspended state is particularly important in order to prevent the laminated blocks of metal from collapsing from side to side. The fact that they are being contrived and piled up on top of each other makes it even more likely to occur. If such a shelf hanging phenomenon occurs, the combustion flame of the burner installed at the bottom of the furnace body will not reach such laminated blocks, and furthermore, the heating effect of the exhaust gas will not be fully enjoyed. Moreover, it takes time for the metal ingots that make up such laminated blocks to melt, which worsens the unit consumption.

In addition, such laminated blocks are not introduced into the furnace body in a sufficiently collapsed state and are not dispersed.
Since they are located in the furnace body in a relatively stacked state, a large gap is created between the laminated blocks and the inner surface of the furnace wall, and the exhaust gas blows upward through such a gap. There is a problem in that the efficiency of heat transfer from the heating element decreases, and such blow-through causes local melting in the preheating section, which further aggravates such blow-through phenomenon. Moreover, the uneven flow of exhaust gas caused by the occurrence of such blow-through not only inhibits the preheating effect of the laminated block, that is, the metal base metal, but also causes the metal base metal to melt at a position far away from the lower holding chamber. This promotes the oxidation of the molten metal that is produced, and is a factor in generating a large amount of dross.

On the other hand, as a high-speed melting furnace for a laminated block formed by stacking such metal ingots in multiple stages, the laminated block gradually moved in the passageway extends at the tip of the passageway extending in the horizontal direction.
It has also been revealed that there is a structure in which the melted material is melted by a burner and then dripped downward from a hole provided in the floor of the melting point, and then introduced into a holding chamber. In a melting furnace, the molten metal drips from the upper melting chamber onto the lower dry hearth over a long distance, resulting in thermal loss and oxidation loss of the molten metal. In terms of thermal efficiency, it is necessary to reheat the dropped molten metal on a dry hearth for further melting.
Additionally, there are inherent disadvantages in terms of equipment.

Moreover, in such a fast melting furnace, it is essential to bring the material moved above the hole in the melting chamber into a state of solid-liquid coexistence, melt it almost simultaneously, and drop it downward through the hole in order to improve the unit consumption. However, such a melting operation is extremely difficult in terms of conditions, and it is difficult to handle cases where the material or shape of the melted raw material changes. Furthermore, in the case of aluminum ingots, which have a narrow temperature range in which solid-liquid coexist, the material melts little by little relative to its surroundings, making it extremely difficult to apply this high-speed melting method.

The present invention has been made in view of the above circumstances, and its purpose is to produce a laminated block made by stacking metal raw materials, particularly aluminum or aluminum alloys, in multiple tiers. When melting is carried out in a vertically installed melting chamber, such laminated blocks are effectively collapsed when they are introduced, thereby suppressing the occurrence of such a hanging phenomenon of the laminated blocks and the blow-by phenomenon of exhaust gas, and thereby preventing the stacking of the blocks from occurring. The objective is to enable efficient use of energy for melting operations.

In the present invention, in order to achieve this object, a laminated block formed by stacking elongated, substantially rectangular metal ingots in a horizontal direction and stacked in multiple stages is preheated in a substantially horizontal direction. While preheating is performed in the preheating chamber, the preheating chamber is moved horizontally forward in the preheating chamber, and is opened at the front end of the preheating chamber. The preheated laminated block is pushed forward from an end of the preheating chamber into a melting chamber having an elongated shape with a large size and extending vertically downward, thereby causing the preheated laminated block to fall in a substantially overturned form; The laminated block is melted in the melting chamber by heating with a burner while the laminated shape of the laminated block is broken.

Thus, according to the present invention, a predetermined metal laminated block that is moved horizontally in the preheating chamber is preheated by the high temperature exhaust gas led from the melting chamber, and From the front end, such a laminated block is pushed forward by the advancing action of the rear laminated block, so that it is caused to fall into the melting chamber through its upper opening in a substantially sideways state. As a result, the laminated blocks made of stacked metal ingots easily collapse and are widely dispersed in the melting chamber, resulting in hanging shelves or large gaps between them and the inner wall of the melting chamber. This effectively suppresses the occurrence of phenomena such as exhaust gas blow-by due to the formation of voids.

Furthermore, since the metal base metals that made up the laminated blocks are widely dispersed in the melting chamber, the heat exchange area becomes large.
This makes it possible to efficiently utilize the thermal energy input by the burner, and by effectively suppressing exhaust gas blow-through, local melting of the laminated block (metal base metal) is prevented. This means that the generation of dross (oxidation loss) can also be reduced.

Moreover, such a melting method can be carried out more advantageously using a melting apparatus having the following structure.

In other words, such a melting device (a) accommodates a plurality of laminated blocks made of elongated, substantially rectangular metal ingots arranged horizontally and stacked in multiple stages, and preheats the laminated blocks. (b) a preheating chamber extending in a substantially horizontal direction, the preheating chamber opening at the front end of the preheating chamber and extending vertically downward; The preheated laminated blocks are sequentially moved forward and pushed forward from the end of the preheating chamber, thereby substantially increasing the length in the direction. (c) a melting chamber configured to fall into the shaft part in an overturned state and be melted by burner means provided at the lower part of the shaft part; (c) a melting chamber connected to the lower end of the melting chamber; A holding chamber which is provided and extends in the horizontal direction and accommodates and holds the molten metal obtained by melting the metal base metal forming the laminated block in the melting chamber. It is.

In addition, in such a melting device, the cylindrical shaft portion of the melting chamber has two opposing symmetrical circular arc portions and two mutually parallel shaft portions in order to ensure sufficient strength. It is preferable that the straight section has a cross section extending in the longitudinal direction of the preheating chamber. By tilting downward toward the opening of the provided shaft section, a plurality of laminated blocks can be effectively extruded and moved within the preheating chamber.

Furthermore, the length corresponding to the longitudinal direction of the preheating chamber in the cross-sectional shape (inner surface shape) of the shaft portion of the melting chamber is the lower part on the front end side and the upper part on the rear end side of the laminated block that is moved in the preheating chamber. It is desirable that the length be longer than the length of the diagonal line connecting the blocks, so that the laminated blocks can be thrown in sideways effectively.

Furthermore, the inner surface shape of the preheating chamber is generally made to have a substantially rectangular cross section, since the laminated block of metal base metal is approximately cubic or rectangular in shape. An outlet for discharging the exhaust gas led from the melting chamber side is suitably provided in the side wall portion, thereby effectively enhancing the preheating effect of the stacked block in the preheating chamber by the exhaust gas.

Next, in order to clarify more specifically the method of the present invention and the apparatus for implementing it, the structure of the present invention will be explained with reference to one specific example of the present invention shown in the drawings. I will explain in detail.

First, in FIGS. 1 and 2, the melting device 2 according to the present invention includes a preheating chamber 4 located above and extending in the horizontal direction, and at the front end of the preheating chamber 4.
It has a melting chamber 6 that opens to the floor and extends vertically downward, and a holding chamber 8 that is connected to the lower end of the melting chamber 6 and extends horizontally. At the entrance of the preheating chamber 4, there is a charge door 10 that can be raised and lowered.
is provided so that the inlet of the preheating chamber 4 can be opened and closed by the vertical movement of the cylinder 12. On the other hand, the exhaust gas is introduced into the lower part of the side wall of the preheating chamber 4 in the vicinity of the inlet. A discharge port 14 is provided for discharge.

Further, as clearly shown in FIG. 2, the melting chamber 6 has a shaft part 16 having an elongated opening (cross-sectional shape), and a lower part of the shaft part 16 has a shaft part 16 that is made to be dropped. A burner device 18 for melting a laminated block of metal base metal is provided on each opposing side wall portion, and the combustion flame or combustion of the burner device 18 is emitted from the burner port 20 inclined downward. The exhaust gas is brought into contact with the metal base metal constituting the fallen laminated block.

The molten metal 22 obtained by melting in the melting chamber 6 is led to the holding chamber 8, and is accommodated and held therein.
A burner device 24 is provided to keep the molten metal 22 held warm.

On the other hand, a material charging device 26 is provided close to the entrance side of the preheating chamber 4 of the melting device 2. This material charging device 26 includes a slat conveyor 28, an alignment device 30, a lifting device 32, a cart 36 that can be guided by rails 34 and can approach the entrance of the preheating chamber 4, and a pusher 38. ing.
In the case of such a material charging device 26, the material to be charged into the melting device 2, that is, the laminated block 40 of a predetermined metal ingot is slatted by a forklift or other suitable method. It is placed on the conveyor 28 and transported by the slat conveyor 28 to a lifting position by a lifting device 32. The laminated blocks 40 stopped at this lifting position are moved to the alignment device 30 in order to correct the collapse of the load caused during transportation.
They are aligned at . Next, the aligned laminated blocks 40 are lifted up by the lowered lifting device 32 and placed on the truck 36, and then placed on the truck 36 at the entrance of the preheating chamber 4.
The laminated block 40 is inserted into the preheating chamber 4 by bringing the stacked blocks 40 close together and pushing them out with the pusher 38 while the charge door 10 is open.

By the way, the laminated block 40 inserted into the preheating chamber 4 of the melting device 2 is made by horizontally disposing a long, substantially rectangular metal base metal 42, as shown in FIGS. 3a and 3b, for example. While arranging multiple levels (here 6 levels, however, the four metal base metals at the bottom 4)
The metal base metals 42 constituting each of the upper and lower adjacent steps intersect with each other in a direction substantially perpendicular to each other. They are piled up.

Further, as shown in FIGS. 4a, b, and c, the metal base metal 42 constituting the laminated block 40 illustrated here has an approximately trapezoidal cross section as a whole in most of its longitudinal direction. As shown in FIG. 3b, the plurality of metal base metals 42 are alternately combined and arranged parallel to each other so that the vertical directions are opposite to each other at each step. It is.

Incidentally, such a metal base metal 42 is referred to as a so-called pig, and its shape is most commonly shown in FIGS. 3 and 4. In addition, as is well known, there is no problem with other cross-sectional shapes such as rectangular shapes, and furthermore, even in the case of a stacked structure of metal ingots 42, the structure shown in the example is not applicable. The present invention is not limited to this, and any structure may be used as long as the metal base metals 42 are arranged horizontally and stacked vertically in multiple stages. In particular, in the present invention, the metal base metal 42 is made of aluminum or an alloy thereof.

In this way, the laminated block 40 of the predetermined metal base metal 42 is placed on the pusher 38 in FIG.
When pushed into the preheating chamber 4 by the protruding action of
The laminated block 40 that was previously loaded into the preheating chamber 4 is slid forward on the floor surface of the preheating chamber 4, and is moved forward by the pushing amount due to the protruding action of the pusher 38. It becomes. As the laminated blocks 40 are sequentially loaded into the preheating chamber 4 in this manner, the laminated block 40 located furthest forward reaches the front end of the preheating chamber 4. In addition, this preheating chamber 4
The laminated block 40 is moved from its inlet to the front end where the dissolution chamber 6 opens.
is preheated by the flow of high-temperature exhaust gas led from the melting chamber 6, and is brought into a semi-molten state or a state where it is easily melted.

In addition, in this embodiment, the floor surface 44 of the preheating chamber 4
is inclined downward toward the opening of the melting chamber 6 provided at its front end, so that the laminated block 40 can be easily pushed forward. Further, the cross section of the preheating chamber 4 has a substantially rectangular inner surface shape so that the exhaust gas can evenly pass around the laminated block 40, and an exhaust port 14 provided at the lower part of the inlet section The presence of the laminate block 40 is designed to allow the thermal energy of the hot exhaust gas to be effectively used for preheating the laminated block 40.

Further, the laminated block 40 that has been preheated while being pushed forward in the preheating chamber 4 is moved from its front end to the melting chamber 6, specifically the shaft portion 1.
The laminated block 40 that has been dropped is pushed forward from the end of the preheating chamber 4 by the pushing action of the laminated block 40 located behind it, and this As a result, it was essentially rolled over onto its side and dropped.

Laminated block 4 in such a preheating chamber 4
0, and the falling form of the laminated block 40 from the front end of the preheating chamber 4 to the melting chamber 6 is the fifth state.
Shown chronologically (systematically) in figures a-d.

That is, in FIG. 5, a indicates the laminated block 40 that has been pushed and moved to the front end of the preheating chamber 4 and has already been preheated to a predetermined temperature.
The figure shows the arrangement of a (dropped into the melting chamber 6) and 40b located behind it. In this state, the charge door 10 at the entrance of the preheating chamber 4 is opened and a new When the laminated blocks 40 are pushed in by the pusher 38, the plurality of laminated blocks 40 located in the preheating chamber 4
are successively pushed forward, so that the stacked block 40 to be dropped, which is located furthest forward,
a is pushed forward by the laminated block 40b behind it, as shown in FIG. 5b.
When the extrusion amount further increases, the fifth
As shown in FIG. The laminated block 40a begins to fall while being rotated, and finally, as shown at d, the laminated block 40a falls into the melting chamber 6 in a substantially horizontal position.

Therefore, when the laminated block 40 is dropped in a substantially horizontal position, the laminated block 40 easily collapses, and as shown in FIG. 1, the metal base metal 42 is relatively scattered. Thus, it is spread inside the melting chamber 6. The laminated block 40, which is formed by stacking metal ingots 42 vertically in multiple stages, is extremely resistant to collapse under vertical forces, but extremely easy to collapse under lateral forces. This is because (see Figure 3).

If such a laminated block 40 is dropped on its side and the metal ingots 42 are dispersed in the melting chamber 6 in pieces, the laminated blocks 40 may remain stacked. In this configuration, there is no possibility of clogging in the middle of the melting chamber 6 or causing a hanging state, and therefore, each metal ingot 42 dropped into the melting chamber 6 is completely removed from the burner device 18. It is effectively heated and melted by the combustion flame or combustion exhaust gas, and the exhaust gas is prevented from being absorbed by the large gap formed between the laminated block 40 and the inner surface of the melting chamber 6, as in the conventional case. The blow-through phenomenon is also effectively eliminated, and the energy input from the burner device 18 can be effectively utilized to the maximum extent for heating and melting the metal base metal 42. Furthermore, since there is no blow-through of exhaust gas, there is no local melting of the laminated blocks 40, and therefore the generation of dross can be reduced to the utmost.

In addition, in this illustrative specific example, the dissolution chamber 6
The cross-sectional shape (inner surface) of the shaft portion 16 of
As specifically shown in the figure, two opposing symmetrical circular arc sections 46 and two mutually parallel straight sections 48
The linear portion 48 is positioned so as to extend in the longitudinal direction of the preheating chamber 4, thereby increasing the strength of the wall portion.
Further, as described above, the cross-sectional shape of the shaft portion 16 and, by extension, the melting chamber 6 is an elongated shape in which the length in the longitudinal direction of the preheating chamber 4 is larger than the length in the width direction of the preheating chamber 4. , the aforementioned laminated block 40 can be effectively dropped in an overturned state, and thus the laminated block 4
It is possible to perform an effective collapse of 0. Moreover, by forming the elongated cross-sectional shape in this way, it is possible to effectively prevent blow-by of the exhaust gas in the width direction, and recovery of thermal energy from the exhaust gas led from the melting chamber 6 to the preheating chamber 4 is possible. This meant that it could be further improved.

Further, generally, a plurality of laminated blocks 40 are placed in the melting chamber 6, and the laminated blocks 40 (metal base metal 42) are sequentially melted starting from the lower one. At this time, the collapsed upper laminated block 40 is further heated by the exhaust gas guided upward through the gaps therebetween.

Note that such a horizontally elongated shaft portion 16
The cross-sectional shape of the melting chamber 6 is not limited to those shown in the example, but various elongated cross-sectional shapes such as oval, oval, rectangular, or a combination thereof can be adopted. It is. Also,
The length corresponding to the longitudinal direction of the preheating chamber 4 in the cross-sectional shape of the shaft portion 16 is the diagonal line connecting the lower front end and the upper rear end of the laminated block 40 that is moved within the preheating chamber 4. It is preferable that the length is longer than the length (l in FIG. 5), thereby allowing the laminated block 40 to fall into the shaft portion 16 more effectively.

In this way, the molten metal 22 obtained by melting the metal ingot 42 in the melting chamber 6 flows over the inclined hearth of the melting chamber 6 and immediately flows into the holding chamber 8. It will be done. Inside this holding chamber 8, molten metal 22
is heated by the burner device 24, raised to a predetermined temperature, and maintained.

Although the present invention has been described in detail with respect to one specific example, the present invention is not to be construed as being limited only to such specific example and the explanation accompanying it, and it does not depart from the spirit of the present invention. It goes without saying that various changes, modifications, improvements, etc. can be made to the present invention based on the knowledge of those skilled in the art, and the present invention includes such embodiments. This is what is intended.

Furthermore, although the present invention was developed specifically for melting base metals made of aluminum or its alloys, it can also be applied to melting base metals made of other metals.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional front view of essential parts of an apparatus suitable for carrying out the present invention, FIG. 2 is a schematic cross-sectional view of the apparatus shown in FIG. 1, and FIGS. They are a plan view and a right side view of a laminated block made of stacked gold, and are
5 and c are respectively a perspective view, a cross-sectional view, and a vertical cross-sectional view of the metal ingots constituting the laminated block, and FIGS. 5 a to d respectively show the state in which the laminated block is rolled over and dropped from the preheating chamber to the melting chamber. FIG. 2: Melting device, 4: Preheating chamber, 6: Melting chamber, 8:
Holding chamber, 10: Charge door, 14: Discharge port, 1
6: Shaft part, 18: Burner device, 22: Molten metal, 26: Material insertion device, 28: Slat conveyor, 30: Aligning device, 32: Lifting device, 3
4: Rail, 36: Trolley, 38: Pushya, 4
0, 40a, 40b: Laminated block, 42: Metal base metal, 44: Floor surface, 46: Arc part, 48: Straight part.

Claims (1)

[Scope of Claims] 1. A laminated block formed by horizontally arranging rectangular metal ingots and stacking them in multiple stages is preheated in a preheating chamber extending in a substantially horizontal direction; move horizontally forward,
Then, the melting chamber is opened at the front end of the preheating chamber and has an elongated cross-sectional shape whose length in the longitudinal direction is larger than the length in the width direction of the preheating chamber and extends vertically downward. The preheated laminated block is pushed forward from the end of the preheating chamber to fall in a substantially overturned form, and the laminated block is heated with a burner in the melting chamber while the laminated shape of the laminated block is disrupted. 1. A method for melting metal ingots, characterized by melting metal ingots. 2. The melting method according to claim 1, wherein the laminated blocks are stacked such that the metal base metals of each stage intersect with each other in a direction substantially perpendicular to each other. 3. The melting method according to claim 1 or 2, wherein the metal base metal has a substantially trapezoidal cross section in most of its longitudinal direction. 4. The melting method according to any one of claims 1 to 3, wherein the metal base metal is made of aluminum or an alloy thereof. 5. A preheating chamber extending in a substantially horizontal direction and accommodating a plurality of laminated blocks formed by stacking elongated substantially rectangular metal ingots horizontally in multiple stages and preheating the laminated blocks; A shaft portion that opens into the floor surface at the front end of the preheating chamber and extends vertically downward, and has an elongated cross-sectional shape whose length in the longitudinal direction is longer than the length in the width direction of the preheating chamber. The preheated laminated blocks are sequentially moved forward and pushed forward from the end of the preheating chamber, thereby being dropped into the shaft portion in a substantially overturned state. , a melting chamber configured to be melted by a burner means provided at the lower part of the shaft part; and a melting chamber extending horizontally and connected to the lower end of the melting chamber, in which the laminated block is melted. An apparatus for melting metal ingots, comprising: a holding chamber that accommodates and holds molten metal obtained by melting the metal ingots that constituted the ingots. 6. The cross-sectional shape of the shaft part of the melting chamber is composed of two opposing symmetrical circular arc parts and two mutually parallel straight parts, and the straight parts extend in the longitudinal direction of the preheating chamber. A melting device according to claim 5, which is located in a. 7. The melting device according to claim 5 or 6, wherein the floor surface of the preheating chamber is inclined downward toward the opening of the shaft section provided at the front end. 8. The melting device according to any one of claims 5 to 7, wherein the preheating chamber has a substantially rectangular cross section. 9 In the cross-sectional shape of the shaft portion of the melting chamber, a length corresponding to the longitudinal direction of the preheating chamber is a diagonal line connecting the lower front end side and the upper rear end side of the laminated block moved within the preheating chamber. Claims 5 to 8 that are longer than the length
The dissolving device according to any of the paragraphs. 10. The melting device according to any one of claims 5 to 9, wherein a side wall on the inlet side of the preheating chamber is provided with an outlet for discharging exhaust gas led from the melting chamber side.