JPH0810926A - Apparatus for supplying molten magnesium - Google Patents

Abstract

PURPOSE:To get rid of a trouble caused by the development and the growth of a stuck material because a chemically stable ceramic material is used by using a molten magnesium supplying apparatus forming an injection piston and an injection sleeve with anyone among graphite, boron nitride, alumina ceramic and zirconia ceramic. CONSTITUTION:The molten magnesium M incorporated in a melting furnace 3 with a piston 6 sliding the inner part of the injection sleeve 5 fixed to a base plate 8 hung down from a top plate 4 in the melting furnace 3 is supplied through a molten metal supplying pipe 10 communicated with the outer part via a passage of the molten magnesium M bored in the base plate 8. The injection piston 6 and the injection sleeve 5 are formed with anyone among the graphite, boron nitride, alumina ceramic and zirconia ceramic. By this constitution, the continuously stable drive is secured by using the ceramic material having the chemically stable property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnesium hot water supply device, and more particularly to a magnesium hot water supply device designed to smoothly maintain the movement of an injection piston that slides in an injection sleeve.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an inert gas is supplied into a melting pot 2 of a melting furnace 3 to prevent the molten magnesium M from being oxidized, and a vertical injection sleeve 5 attached to a base plate 8 is provided. The injection piston 6 is lowered to supply a certain amount of molten magnesium M to the molten metal passage 8 inside the base plate 8.
A magnesium hot water supply device 1 has been proposed which is supplied into the die casting sleeve 20 of a die casting machine via a and the hot water supply pipe 10. That is, the magnesium hot water supply device 1 includes an upright cylindrical melting pot 2 which is housed inside a melting furnace 3 and has a lid (top plate) 4.
A base plate 8 which is suspended horizontally in the melting pot 2 and has a molten metal passage 8a therein, and an injection piston 6 which is erected vertically on the upper surface of the base plate 8 and communicates with the molten metal passage 8a and has both ends opened and which is slidable inside. The injection sleeve 5 provided with the molten metal passage 8 of the base plate 8 which has an opening 8b at one end and is connected orthogonally to the lower end of the injection sleeve 5 and extends outside the furnace.
a, the hot water supply pipe 10 connected thereto, and the molten metal passage 8
It is formed by a suction valve 7 that shuts off molten magnesium (hereinafter referred to as molten metal) M to a and a check valve 19 in the molten metal passage 8 a of the base plate 8. On the lid (top plate) 4, for an injection cylinder 11 connected via an injection piston 6 and a piston rod 12, a hydraulic cylinder 16 connected via a suction valve 7 and a valve rod 17, and a check valve 19. Hydraulic cylinder 1
9A and 9A are mounted and fixed, and an inert gas injection pipe 9 for sealing the inert gas into the melting pot 2 is attached. The injection sleeve 5 forms a pressure chamber for taking out the molten metal M in the melting pot 2 to the outside of the furnace, opens the suction valve 7 and puts the check valve 19 in a lowered state (closed state).
After raising the injection piston 6 and sucking the molten metal M, the suction valve 7 is closed and the check valve 19 is raised (open state).
Then, by lowering the injection piston 6, the molten metal M filling the molten metal passage 8a is conveyed to the outside of the furnace via the hot water supply pipe 10, and passes through the external hot water supply pipe 14 connected to the hot water supply pipe 10. Die casting sleeve 2 near the furnace
0 is discharged into the mold of a die casting machine (not shown) as the die casting piston 21 moves forward.

The injection piston 6 is formed integrally with the piston rod 12 as shown in FIG. 4, or is welded to the piston rod 12, or, as shown in FIG. 5, a flat washer 12a is sandwiched. It was formed so as to be screwed and coupled with the nut 12b.

[0004]

The injection piston 6 formed in this way is, for example, S-type at the same time as the injection sleeve 5.
Since it is made of tool steel such as KD61, with the lapse of operating time, it chemically reacts with the molten metal to produce aluminum manganese iron (AlFeMn) on the sliding surface, which adheres and grows. The clearance formed between the inner surface of the injection sleeve 5 (usually 0.5 mm
(Tolerance of about 1 mm) has disappeared, sliding operation is not smooth, the power required for the reciprocating motion of the injection piston 6 becomes excessive, and in extreme cases it may cause inoperability or damage to equipment. Was occurring.

[0005]

In order to solve the above problems and prevent the growth of deposits on the inner peripheral surface of the injection sleeve and the outer peripheral surface of the injection piston, the present invention provides:
The molten magnesium stored in the melting furnace by the injection piston sliding inside the injection sleeve fixed to the base plate suspended from the top plate in the melting furnace is passed through the molten magnesium passage formed in the base plate to the outside. In a magnesium hot water supply device that supplies water through a hot water supply pipe communicating with, the injection piston and the injection sleeve were made of any one of graphite, boron nitride, alumina ceramics, and zirconia ceramics. Further, in the second invention, the outer cylinder made of any one of graphite, boron nitride, alumina ceramics, and zirconia ceramics is further fitted and engaged with the injection piston.

[0006]

In the present invention, the injection piston and the injection sleeve are made of graphite, boron nitride, ceramics such as alumina and zirconia instead of the steel material, so that the reaction with molten magnesium is prevented and the growth due to the adhesion of the chemical reaction product. Eliminating the enlargement maintains the desired tolerance between the injection piston and the injection sleeve and ensures a smooth reciprocating motion of the injection piston.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 relate to an embodiment of the present invention,
1 is a vertical sectional view of an injection piston, FIG. 2 is a vertical sectional view of an injection piston showing another embodiment, and FIG. 3 is a process drawing showing a manufacturing process of ceramics. In FIG. 1, a cylindrical inner cylinder 5B is fitted inside the main body 5A of the injection sleeve 5, both are integrated by a bolt 5d at the top, and a cylindrical injection piston 6 having a through hole in the center is formed. Further, the piston rod 12 having a threaded penetration portion at the lower end is penetrated into the through hole, and is screwed with a nut 12b through a plain washer 12a to be integrated. Injection piston 6 and cylinder 5
The material of B is graphite, boron nitride (BN), alumina ceramics (Al2 O3), zirconia ceramics (Z
rO2), as shown in FIG. 3, necessary additives are added to the raw material powder, and various moldings are performed, followed by firing to obtain a product. As a molding method, a device such as a hydrostatic press, a hot press, a hot hydrostatic press, a doctor blade method, an injection molding method, or the like is adopted. In FIG. 2, the injection sleeve 5 is formed in the same manner as in FIG.
A cylindrical outer cylinder 6B is fitted to a cylindrical main body 6A made of a steel material such as No. 1 and screwed with a nut 12b through a flat washer 12a to be integrated. 1 is one of graphite, boron nitride (BN), alumina ceramics (Al2 O3) and zirconia ceramics (ZrO2) as in FIG.

Next, the reason for selecting the material of the inner cylinder 5B of the injection piston 6 and the injection sleeve 5 of FIG. 1 and the outer cylinder 6B of FIG. 2 will be described. (1) Graphite As the graphite, isotropic high density and high purity graphite is adopted. Among the ceramics, this graphite is easy to machine, and its characteristics are self-lubricating property, large electrical conductivity, and large thermal conductivity. In addition, it has high heat resistance, is difficult to wet with molten metal, and has a low specific gravity. Furthermore, the coefficient of thermal expansion is small,
It is chemically stable and has high temperature strength. Among the reasons described above, the reason why the injection piston 6 and the outer cylinder 6B are mainly used is that the heat resistance is high, the wettability to the molten metal is low, the chemical stability is high, and the high temperature strength is high.
This is because it is easy to maintain the required tolerance due to its small coefficient of thermal expansion. In the manufacturing process, an isotropic high-density graphite material having a small particle size is isostatically pressed and then fired to obtain a product. (2) Boron Nitride (Boron Nitride) Boron nitride (BN) is a colorless powder and belongs to the hexagonal crystal form.
It has properties similar to graphite, and unlike ceramics containing silicon (Si) such as silicon nitride (Si3 N4) and silicon carbide (SiC), it does not react with molten magnesium and is chemically stable. The manufacturing method is to heat boron (B) to 1500 ° C. in a nitrogen stream, or to heat ammonia and boron oxide or ammonium chloride and borax. Products of the injection piston 6 and the outer cylinder 6B are manufactured by molding and firing fine powder of boron nitride in the same process as graphite. (3) Alumina ceramics (Al2 O3) Alumina ceramics are most often used among new ceramics, from thin plates of 0.05 mm to diameters of 500 m.
It is possible to manufacture large objects with m and length of 2000 mm. Besides being chemically stable, the strength of Al2 O3 is 300-500M.
At Pa, it is relatively large among oxide-based ceramics, but at 1000 ° C. or higher, the strength decreases. Since the molten metal in the present invention is 650 to 700 ° C, there is no problem. Its thermal expansion coefficient is slightly larger than that of Si3 N4, and its thermal shock resistance is low, but it is a material that is inexpensive, has a high hardness, and has excellent corrosion resistance and wear resistance. The manufacturing method is the same as in (1) and (2), in which fine powder is molded and then fired. (4) Zirconia ceramics (ZrO2) Pure ZrO2 has the property of undergoing a phase transition from monoclinic to tetragonal at around 1000 ° C and causing a volume change of about 4.6%. Is 700 ° C. or less, so there is no problem. To improve the above characteristics,
There is cubic zirconia stabilized with Y2O3 or CaO in solid solution, and this may be used. Partially stabilized zirconia has a high strength of 1000 to 1500 MPa and a high fracture toughness of 10 to 15 MN / m3 / 2, and is among the highest grades in the present new ceramics. Zirconia ceramics are often used for wear-resistant products such as dies, guide rollers, jigs and tools, but their thermal conductivity coefficient is small,
It has characteristics similar to cast iron with a coefficient of thermal expansion, and is also used in heat-insulating diesel engine parts. Of course, it is also suitable for the injection piston of the present invention. As in the other manufacturing methods, the fine powder is molded and then fired.

The ceramic molded product as described above is
In both cases, the secondary processing is very expensive due to the high hardness material, so the injection piston 6 and the outer cylinder 6B have a simple and simple shape as shown in FIG. 1 and FIG. It is desirable not to request. In general, shrinkage in the process of drying and firing in the manufacturing process of ceramics,
Since the deformation is large, it is necessary to consider this point and maintain the shape of the final product and the required dimensions. New ceramics are still in the development stage, and there is a possibility that new materials with unique properties and materials with significantly superior performance will emerge in the future due to improvements in conventional new ceramics. Therefore, it is expected that the number of ceramic materials suitable for the injection piston and the injection sleeve in the present invention will increase in the future and the range of selection will expand. In the magnesium hot water supply apparatus 1 of the present invention including the injection piston 6 and the injection sleeve 5 formed as described above, there is no development of deposits due to chemical reaction due to aging, and the tolerance at the beginning of operation is maintained. The vertical movement of the injection piston 6 is carried out.

[0010]

EFFECTS OF THE INVENTION Since the injection piston and the like in the present invention use a ceramic material having a chemically stable property, troubles due to the growth and enlargement of deposits are eliminated, and continuous stable operation is secured.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an injection piston according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of an injection piston according to another embodiment of the present invention.

FIG. 3 is a process drawing showing a manufacturing process of ceramics according to the present invention.

FIG. 4 is an overall vertical sectional view of a conventional magnesium water heater.

FIG. 5 is a vertical sectional view of a conventional injection piston.

[Explanation of symbols]

 1 magnesium hot water supply device 2 melting pot 3 melting furnace 4 lid (top plate) 5 injection sleeve 5a bolt 5b nut 5c flange 5d bolt 6 injection piston 6A body 6B outer cylinder 7 suction valve 8 base plate 8a molten metal passage 8b opening 9 inert Gas injection pipe 10 Hot water supply pipe 11 Injection cylinder 11a Piston rod 12 Piston rod 12a Plain washer 12b Nut 13 Shaft joint 14 Outer hot water supply pipe 15 Stand 16 Hydraulic cylinder 17 Valve rod 18 Heater 19 Check valve 19A Hydraulic cylinder 20 Die casting sleeve 21 Die casting piston 30 Piping joint M Molten magnesium (molten metal)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C04B 35/583 F04B 15/00

Claims (2)

[Claims] 1. A molten magnesium passage formed by piercing the molten magnesium contained in the melting furnace by an injection piston that slides inside an injection sleeve fixed to a base plate suspended from a top plate in the melting furnace. In a magnesium hot water supply device which supplies water through a hot water supply pipe communicating with the outside through the magnesium hot water supply device, wherein the injection piston and the injection sleeve are made of any one of graphite, boron nitride, alumina ceramics and zirconia ceramics. apparatus. 2. A molten magnesium passage formed by piercing the molten magnesium contained in the melting furnace by an injection piston that slides inside an injection sleeve fixed to a base plate suspended from the top plate in the melting furnace. In a magnesium water heater that supplies water through a hot water supply pipe that communicates with the outside via graphite, the sliding surface of the injection piston and the injection sleeve has graphite, boron nitride,
A magnesium hot water supply device characterized in that an outer cylinder made of either alumina ceramics or zirconia ceramics is fitted and engaged.