JPH02148B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an injection method for a die casting machine for injecting molten metal into a cavity of a mold.

[Conventional technology]

Die casting machines are classified into vertical casting machines and horizontal casting machines, depending on the direction in which the molten metal is injected into the mold cavity. Among these, the injection device of the vertical casting die casting machine consists of a fixed sleeve that is formed into a half-cylindrical shape and is fitted below the mold cavity and opens and closes with the mold, and a fixed sleeve that can be freely attached to and removed from the lower end of the clamped fixed sleeve. An injection cylinder that has an injection sleeve joined to the injection sleeve and an injection plunger that is vertically movably fitted to the injection sleeve and moves up and down by hydraulic pressure, and that stands upright, tilts, or moves horizontally while standing upright together with the injection sleeve. It is equipped with In such an injection device, the molten metal in the melting furnace is supplied to the injection sleeve, which is separated from the fixed sleeve and tilted together with the injection cylinder, by an automatic water supply device or a manual ladle. After filling the injection sleeve, the injection sleeve moves together with the injection cylinder and is joined to the fixed sleeve.Then, by raising the injection plunger using hydraulic pressure, the molten metal in the injection sleeve is injected into the mold cavity through the fixed sleeve. be done.

[Problem that the invention seeks to solve]

However, such conventional injection methods require large melting furnaces, automatic water heaters, etc., which not only increases equipment costs and requires a large space, but also requires a large amount of molten metal to be injected for each injection. It is difficult to keep it constant and there is a large energy loss.
Impurities such as oxides are often generated. In addition, maintenance costs for the furnace are high, and not only the entire amount of molten metal in the furnace cannot be used, but also equipment for a melting furnace and forehearth is required, and it is also necessary to transport the molten metal from the melting furnace to the holding furnace. If the amount of molten metal is not constant, the quality of die-cast products will vary, resulting in poor productivity, high energy loss, and the need for special equipment for quantitative injection.

[Means for solving problems]

In order to solve these problems, in the present invention, the melting jig is gradually lowered to the axial center of a billet of a size necessary for one injection, leaving the outer periphery and bottom of the billet intact. The inside of the billet is melted in advance, and the billet with the inside melted is fed into the injection sleeve, and the injection sleeve is heated from the outer circumferential side to melt the entire billet and inject it into the mold cavity. I did it like that.

[Effect]

By doing this, when the billet whose inside has been melted with the melting jig is supplied to the injection sleeve and heated from the outer circumferential side, since the inside has already been melted, the billet will melt extremely quickly and become molten metal, which will melt into the injection cylinder. When the plunger is moved forward, molten metal is injected into the mold cavity. If one injection cylinder and a plurality of injection sleeves each having a plunger detachably connected to the piston are provided, while one set of injection sleeves is injecting, the other injection sleeves are injecting. The billet can be heated and melted inside.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view of a rotary table type injection device of a die-casting machine shown for explaining the injection method for a die-casting machine according to the present invention, and FIG. 2 is a perspective view of a preheating container. In the figure, a die casting machine 1 is equipped with a pair of upper and lower fixed plates 3 (the upper fixed plate is not shown) whose four corners are connected by tie rods 2, and a movable plate 4 is fitted at the four corners of the tie rods 2. They are supported so that they can move up and down. Fixed plate 3
A fixed mold 5 and a movable mold 6 are attached to the movable platen 4, and a cavity 7 is formed in both molds 5 and 6 with a dividing surface 8 as a boundary. A piston rod 9 of a mold clamping cylinder fixed to the upper fixed plate is fixed to the movable platen 4, and the molds 5 and 6 are clamped and opened by moving the piston rod 9 forward and backward using hydraulic pressure. It is configured as follows. Reference numeral 10 denotes a fixed sleeve formed in a cylindrical shape and fitted onto the fixed platen 3, whose flange portion is engaged with the fixed mold 5, and whose inner hole is communicated with the cavity 7.

On the other hand, a motor 12 and a bearing 13 are fixed in parallel on a frame 11 located below the fixed platen 3 and fixed to the fixed platen 3 side. A rotary table 16 on which a rotary table 14 is supported so as to be movable up and down via a guide 15 is rotatably supported. A pinion 17 attached to the motor shaft of the motor 12 and a gear 18 fixed to the rotary table 16 are in mesh with each other, and by rotating the motor 12, the rotary table 16 is rotated alternately forward and backward by 180 degrees. The sleeve bases 14 on both sides rotate in the direction shown in FIG.
are arranged to alternately occupy positions immediately below the fixed sleeve 10. Furthermore, the fixing sleeve 10
Directly below is the injection cylinder 1 which is concentric with this.
A piston rod 9 is supported by a frame 20 on the side of the fixed platen 3, and a coupling 21 formed in a U-shape is fixed to the working end of the piston rod, which moves forward and backward with hydraulic pressure. Reference numeral 22 denotes an integral injection sleeve formed into a cylindrical shape and fitted into the center hole of each sleeve base 14 on both sides, and has an inner hole with approximately the same diameter as the fixed sleeve 10. A plunger tip 24, which is the head of an injection plunger 23, is slidably fitted into the plunger. The flange 23a at the lower end of the injection plunger 23 is configured to engage with the coupling ring 21 when the injection sleeve 22 rotates to a position concentric with the injection cylinder 19 with the plunger 23 lowered to its lower limit. . In addition, on the bottom surface of the fixed platen 3,
A shift cylinder 25 is attached, and a shifter 27 is fixed to the working end of the piston rod 26. When the collar 23a engages with the coupling 21, the groove of the shifter 27 engages with the sleeve base 14. The injection sleeve 22 is configured to move up and down as the piston rod 26 moves back and forth. The injection sleeve 22 is in the lowered position as shown in the figure.
By rising from this state, the fixed sleeve 1
0 and the inner hole communicates with each other.

A cylindrical preheater 28 is disposed near the external position of the injection sleeve 22. Inside the preheater 28, a preheater 28, for example, which is formed in advance to have a predetermined size corresponding to the amount of one injection, is disposed. An aluminum billet 29 is inserted.
30 is a heater such as an induction heater or an electric resistance mounted on the outer periphery of the preheater 28, and 31 is a heater such as an induction heater or electric resistance mounted on the outer periphery of the injection sleeve 22, The heater 31 is set to a higher temperature than the heater 30. Furthermore, the preheater 28
A melting jig such as a carbon electrode 32 that can be raised and lowered, a heater rod covered with a ceramic protective tube, or a plasma melting jig is arranged above, and this is lowered to the axial center of the billet 29. By doing so, the inside of the billet 29 except for the outer periphery and the bottom is melted. The billet 29 whose interior has been melted in this manner is transferred to the injection sleeve 22 and heated and melted by a heater 31. Reference numeral 33 indicates molten metal produced by melting the billet 29, and the molten metal 32 is injected into the cavity 7 as the plunger tip 24 rises.

An injection method using a die casting machine having a rotary table type injection device configured as described above will be explained.

A billet 29 of a size necessary for one injection is supplied into the preheater 28 and then heated from the outside by the heater 30.
When heated to about 450 to 500°C and lowered the carbon electrode 32 to the axial center of the billet 29,
The billet 29 is melted leaving the outer periphery and the bottom. When the billet 29 that has been heated and melted in this way is moved into the outer injection sleeve 24 and heated by the heater 31, it is melted in a short time and the molten metal 33 is heated because it has been preheated and melted in advance. becomes. Therefore, when the motor 12 is rotated in the forward direction, the rotary table 16 rotates 180 degrees to rotate the molten metal 33.
The injection sleeve 24 is located directly below the fixed sleeve 10 and the flange 23a of the plunger 23 engages with the coupling ring 21, so that the shift cylinder 1
When the piston rod 26 of No. 9 is raised hydraulically,
The sleeve base 14 that engages with the shifter 27 is the guide 1
5, the injection sleeve 22 is crimped and joined to the fixed sleeve 10. Then, when the piston rod of the injection sleeve 19 is advanced, the plunger 23 that engages with the coupling ring 21 rises.
The molten metal 33 is pushed up by the plunger tip 24 and injected into the cavity 7. After waiting for the molten metal 33 in the cavity 7 to solidify, the movable mold 6 is opened and the product is taken out. Further, the plunger 23 and the injection sleeve 32 are lowered to the illustrated positions.

Then, the molten metal 33 in one injection sleeve 22
During the injection, the other injection sleeve 22 is stopped on the outside, so during this period, the billet 29 is preheated and internally melted in the preheater 28, and then the billet 29 is heated inside the injection sleeve 22. When melting is performed, one injection sleeve 2
Since the molten metal 33 is prepared in the other injection sleeve 22 when the injection from 2 is completed, the next injection can be started immediately by rotating the rotary table 16 by 180 degrees in the opposite direction.

When melting the billet 29 within the injection sleeve, the thermal efficiency is good if the opening of the injection sleeve 22 is closed with a lid, and the thermal efficiency is even better if the pressure inside the injection sleeve 22 is reduced. It is also possible to place the entire preheating section, melting section, and injection section into a vacuum generating chamber and perform preheating, melting, and injection under vacuum. Furthermore, in this embodiment, an example was shown in which the present invention is carried out using a rotary table type injection device of a die-casting machine, but a pair of injection sleeves are provided, and the injection sleeve that has completed injection is linearly moved alternately to the left and right sides of the injection position. Alternatively, the billet 29 may be melted. Alternatively, two sets of injection apparatuses including an injection cylinder, an injection sleeve, and a preheating device may be provided and rotated or horizontally moved as described above. Although it goes without saying that the present invention can be carried out using a normal injection device having one injection sleeve, it is more effective to provide two injection sleeves 22 in order to shorten the casting cycle. . Further, in the above embodiment, the billet 29 is placed in the preheater 28 and melted from the inside leaving the outer circumferential wall, and the billet 29 is preheated from the outside by the heater 30. It is also possible to melt from the inside without putting it into the preheater 28, using only the heater 30, or without using the heater 30, leaving the outer peripheral wall.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, as an injection method for a die-casting machine, the melting jig is gradually lowered to the axial center of the billet to melt only the inside of the billet, and then the melting jig is fed into the injection sleeve. By adopting a method of melting the metal by heating it from the outer circumferential side and injecting the molten metal into the mold cavity, there is no need for a melting furnace or automatic water heater, and equipment costs can be reduced significantly. Instead, it is easy to keep the volume of the billet constant, which makes it possible to inject a fixed amount of molten metal each time, which improves and stabilizes the quality of the cast product, improves productivity, and improves energy efficiency. It also becomes more expensive. Furthermore, if the billet is melted in the other injection sleeve while the molten metal in the other injection sleeve is being injected, the casting cycle can be shortened and productivity can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a rotary table type injection device of a die-casting machine shown for explaining the injection method of a die-casting machine according to the present invention, and FIG. 2 is a perspective view of a billet preheating container and a melting jig. It is. 1... Die casting machine, 5... Fixed mold, 6
...Movable mold, 7... Cavity, 16... Turntable, 19... Injection cylinder, 21... Coupling, 22... Injection sleeve, 23... Plunger, 28... Preheater, 29... Billet, 3
0, 31... Heater, 32... Carbon electrode, 3
3...Molten metal.

Claims (1)

[Claims] 1. While gradually lowering the melting jig to the axial center of the billet that has been made to the size required for one injection, melt the inside of the billet in advance, leaving the outer periphery and bottom of the billet. An injection method for a die casting machine characterized by supplying a melted billet into an injection sleeve and heating the injection sleeve from the outer peripheral side to melt the entire billet and inject it into a mold cavity.