KR20230039619A - Method and Die Apparatus for die casting with additional forging effect - Google Patents

Abstract

Proposed is a method for the die casting with an additional forging effect, in which, just as in a general die casting process, but with molds on the left and right sides or upper and lower sides to be located so that a cavity storing molten metal before the injection of materials can be greater than the volume of a final part, the molten metal is injected. After the metal materials start being coagulated, the molds are additionally moved forward with a great force so that the shape of a final part can be molded from the position. The coagulated materials are forged at a temperature over or under the recrystallization temperature. Therefore, a high shape precision of die casting is provided, but there is no air hole or contraction hole. A dense tissue is generated by a texture successively formed along the shape of the part, so that parts with excellent mechanical properties such as improved strength, abrasion resistance, and toughness can be produced. Thanks to the excellent mechanical properties, the thickness of parts can be reduced, thereby increasing the effect of making the parts lightweight.

Description

Die casting technology and mold apparatus with forging effect added {Method and Die Apparatus for die casting with additional forging effect}

The present invention relates to a die casting method and a mold device capable of casting a liquid metal material at high pressure using a die casting facility having a mechanical locking device or a vertical motion press, and in the present invention, a forging effect can be added to a die casting part. We propose a technique that has

Die casting technology is a part forming technology widely used in the manufacture of automobile and mechanical parts. This technology injects molten metal under high pressure into a cavity inside a mold having a part shape, takes it out after the part is solidified, and is a deburring process. As a production technology that completes a part through a process, it is a suitable technology for forming a part with a complex shape into an integral finished product with high dimensional accuracy.

Die casting is a casting technology that molds a part having the same shape as that of the mold by injecting molten metal into a precisely processed mold. It is widely used throughout the industry where precision metal parts are used because of its excellent mechanical properties and mass productivity of parts by die casting. The filling time of die casting is very short compared to general casting. However, as product shapes become larger and more complex, the existing structure usually does not take enough time to exhaust gas for quality improvement and defect rate reduction. Due to the injection effect during casting, a large part of the molten metal is in contact with the gas inside the cavity, and a vacuum die casting technology with a structure that can more effectively exhaust the residual gas that has not been discharged out of the mold can be introduced to suppress the generation of residual gas. It is impossible to completely remove residual gas inside. Therefore, it may be difficult to mold a product with excellent mechanical properties suitable for the needs of parts that must perform functions under mechanical load with the existing method of shaping a product using a liquid metal material, that is, die casting or squeeze casting. .

Existing die casting or squeeze casting equipment is mainly horizontal or pressurized from the bottom, and the pressure applied to the liquid metal material injected into the cavity of the mold is lower than that of forging, so pores that occur locally inside the molded product It is difficult to remove defects such as cracks or shrinkage. In the case of squeeze casting, although the pressure is relatively high, it is insufficient to completely eliminate the shrinkage cavity defect.

In general, die-casting products mainly use lightweight metals such as aluminum or magnesium as their main material and cast the material above the liquidus line, so the solidification time is long and casting defects such as surface shrinkage or internal pores occur, resulting in inferior mechanical properties. . Therefore, efforts have been made to eliminate the above problems in the existing die casting or squeeze casting methods, but it is still difficult to produce parts having excellent mechanical properties.

Existing die casting or squeeze casting equipment is horizontal or pressurizes molten metal from the bottom, and the pressure applied to the liquid metal material injected into the cavity of the mold is not as high as for forging. Therefore, it is difficult to remove defects such as shrinkage holes generated in local thick parts inside the molded product.

Molding and manufacturing various mechanical parts by die-casting is an optimal method for forming the shape of the part, but due to the casting characteristics of casting, the structure is not dense, shrinkage occurs on the surface of the part, and air bubbles are included in the part. The above general characteristics of die-casting parts make it difficult for them to be used in the manufacture of functional parts subjected to high loads.

Forging is a manufacturing process in which metal is formed using compressive forces. The compressive force is transmitted to a mold by a hammer (often a power hammer) or press to form a metal material, which is stronger and stronger than a cast die-cast or machined part. Parts with good toughness can be produced. As the metal is formed during the forging process, its internal textural organization is deformed to conform to the general shape of the part. As a result, the texture change continuously continues throughout the part, and the structure becomes dense, so that parts with improved strength, wear resistance and toughness are molded. However, in the forging process, the metal material is filled into the mold shape by inducing the flow of the material due to the high compressive force. In principle, since the material is in a solid state rather than a liquid, there are significant restrictions on the flow of the material, especially in thin-walled parts, compared to die casting. There are extremely difficult downsides.

In the present invention, in order to improve the inferior mechanical properties (existence of air bubbles and shrinkage holes in molded parts, less dense metal structure), which are disadvantages in die casting and forging, by adding a forging effect during die casting, the texture of the material is improved and molded A technical method for expanding the use of parts and extending the life of parts by improving the mechanical properties of parts by densifying the structure of parts and removing defects such as air bubbles and shrinkage holes, and a mechanical device that enables the application of the above technologies Its control method and mold device are proposed.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

The present invention proposes a method and apparatus for improving the inferior quality of molded parts, which is a disadvantage, by using the advantages of excellent shape filling of the die casting through the following means.

(i) In a normal die casting process using left and right or top and bottom molds, one mold is provided so that one mold can slide into the other mold,

(ii) the left and right or top and bottom molds are positioned so as to form a cavity for accommodating molten metal, and the cavity is positioned so as to be larger than the volume of the final part to be produced,

(iii) injecting molten metal into the cavity;

(iv) After the solidification of the injected molten metal material starts, one mold is further advanced to the other mold side so that the shape of the final part is formed, so that the structure of the solidified material is densified,

A die casting method with added forging effect, characterized in that it is possible to produce a part having excellent mechanical properties by making an additional forging effect before taking out the part in the same mold simultaneously or continuously with die casting.

Two steps of performing the first forging step by advancing the mold to an intermediate position before the final position in a state where the position of the mold is larger than the volume of the part to be finally molded, and performing the second forging by advancing the mold to the final position. Die-casting method with the addition of a forging effect, characterized in that consisting of.

A die casting method with a forging effect, characterized in that it is made at a temperature above the recrystallization temperature of the molten metal material or at a temperature below recrystallization.

In a state where the position of the mold is larger than the volume of the part to be finally molded, the mold is advanced to an intermediate position before the final position to perform the first forging step, and the mold is advanced to the final position to perform the second forging step. A die casting method with a forging effect added, characterized in that it consists of steps and the forging process is carried out once or several times in each step.

Subplates are provided on the left and right or upper and lower plates of the die casting device, and one or more hydraulic cylinders are provided in the subplate, and a mold plate for mounting a mold is provided on the subplate, so that the hydraulic cylinder is installed during the die casting process. A die casting device characterized in that it operates to control the mold plate to move.

After the mold is moved to the position where the molten metal material is injected in the die casting process, one mold is configured to slide into the other mold and enter, and in the die casting process, when the molten metal is injected in step (iii) Forging, characterized in that a slit or hole that enables the discharge of surplus material that may occur during the further advancement of one mold in step (iv) is provided on the outside of one mold or the other mold Mold for die casting with added effects.

The mold is a die-casting apparatus, characterized in that a slit or hole that enables the discharge of surplus material that may occur in the die-casting process is provided on the outside of one mold or the other mold.

In the present invention, using the excellent shape filling function, which is an advantage of the conventional die casting method, and designing a process to produce an additional forging effect before taking out parts in the same mold simultaneously or continuously with die casting, It is possible to produce parts with excellent mechanical properties that are difficult to obtain in die casting, such as a dense structure by texture continuously formed along the shape of the part without shrinkage holes, and it is possible to increase the thickness of parts by improving mechanical properties such as increased strength, wear resistance and toughness. Since it can reduce the weight and increase the lightening effect, it is very likely that the parts produced by the method proposed by the present invention will be applied to the industry, especially the eco-friendly transportation industry, such as electric vehicles.

1 is a die casting facility equipped with a mold system proposed in the present invention.
Figure 2 is the main components of the present invention.
3 is a state in which the mold is closed to a position before the molten material is injected
Figure 4 is a state in which the molten material is injected.
5 is a state in which the molten material is solidified and the final forging is in progress.
6 is a state of taking out parts after die casting and forging
7 is a press machine to which the mold system of the present invention can be applied.
8 is a mold system of the present invention.
Figure 9 is a process flow by mounting the mold system of the present invention to the press.
Figure 10 is a slit or hole implemented on the outside of the mold system to process the surplus material generated during the process

In a conventional die casting machine, a frame is installed, a fixed or stationary plate 120 is mounted on the frame, and one half of a mold 150, 160 having the shape of a part is mounted on the plate. The other side of the mold is mounted on a movable plate 110 that allows a cast part, which has the shape of the other half of the cast part, to be taken out of the machine after the die casting process, where the mold melts. While being filled with metal, this movable plate closes and locks with enough force to withstand the forces the molten metal exerts on the mold. During operation, following the solidification of the molten metal that has been injected into the mold cavity, the part is separated from one movable plate (110) above the fixed plate, and as the movable one mold part (150) is moved to an open state, the part is moved to the movable plate. The ejector 180 is maintained on one side of the installation. The moving parts of the molds 150, 160 or held on one side with the ejector 180 must be ejected therefrom to be transported or dropped out of the die casting machine with the help of the ejector 180.

One-side movement as described above is one of the causes of various and complicated forms of automatic part transfer mechanisms related to conventional die casting machines that have been repeatedly modified in relation to the part transfer problem. If a similar machine is used, various and complex problems of the automatic parts transfer mechanism will then arise as the parts are entrusted to secondary processes such as trimming. As the parts enter the fixed position for the desired motion, the parts transfer machine requires indexing function and lateral movement to match the plate opening and closing stroke. The machine described in U.S. Patent 4,013,116 consists of a frame, a mold plate, and a hydraulic opening/closing cylinder with a simple deceleration device to eliminate the shock generated when closing. In order to eliminate mold mismatch due to thermal expansion of the die set during mass production of parts, the mold must be able to fit various part shapes and have a predetermined shape in the plate of the die casting machine. The machine's molten metal injection section has a self-contained molten metal supply with electric resistance heater, infinitely variable control that can be preset to any speed or pressure required. equipped The machine itself has a built-in hydraulic power unit and refractory fluid is used.

The mechanical structure of the US patent is the basis of all currently commercialized die casting equipment and is widely used in the industrial field.

Die-casting technology is a production technology suitable for forming lightweight metal into parts of a desired shape, so it is widely used in all industrial fields. That is, compared to forged parts, products molded by die casting have a less dense structure, surface shrinkage may occur, and air bubbles may exist inside. This is fundamentally impossible, or if you dare to mold a part by die casting and use it as a functional part of a machine, there is a problem in that the thickness of the part must be much thicker than that of the forged product.

In the present invention, by integrating the advantages of conventional die-casting and forging, overcoming the limitations of the two production technologies and expanding the range of use of parts, a new die-casting molding technology that actively responds to the needs of areas requiring light weight, such as the latest electric vehicles. suggests

Korean Patent No. 10-0670187 "Multi-stage pressure type die-casting method and mold using press" proposes a method of obtaining a certain level of forging effect by applying multi-stage pressure in the die-casting process, but as can be seen in the patent literature, in the final stage of multi-stage pressure A forging effect is obtained by applying high pressure, but since the area of action of the high pressure is only limited to a part of the die-casted part, when the molten metal material is injected into the mold cavity, the metal material experiences a rapid temperature from the moment it contacts the mold. If the metal material is additionally compressed by pressurizing a part of the part using a hydraulic cylinder after solidification has already started, the effect of pressurization appears only in the part close to the pressurized part, and the pressurization effect is not effective in the place far from the pressurized part. Insufficient or ineffective, it becomes very difficult in reality to obtain the pressurization effect on all parts of the part. Therefore, the effect of pressurization is difficult to be transmitted to all parts of the parts inside the mold cavity, and it is localized only in the vicinity of the injection part.

In order to solve this problem, the present invention proposes a method to obtain excellent mechanical properties of molded parts by specially designing the structure and control of the machine and the structure of the mold so that the effect of pressurization can be applied to all parts of the part. do.

There are several ways to improve the mechanical properties of molded products with metal materials. One is the proper selection of metal materials and the other is the design of suitable molding processes. The present invention is a technology that supplements the disadvantages of existing die casting by adding a forging effect to parts while maintaining the excellent shape-filling characteristics of existing die casting by newly proposing a forming process. That is, by introducing a forging process in addition to the die casting process, the forging effect can be achieved by improving the existing die casting facility concept, control method, and mold design.

In order to achieve the forging effect, the die-casting part is injected from molten metal into the cavity formed by the molds 150 and 160, and then the shape filling is completed and the material temperature is higher than the recrystallization temperature or solidification is in progress while solidification is in progress. When the temperature of the material falls below the recrystallization temperature, the molded part is additionally compressed once or several times by moving the moving part mold 150. In the existing die casting facility, when the moving part mold 150 is closed, a cavity is formed between both molds by the union of the molds, and this cavity determines the final shape of the product, and further compression movement is impossible, further compressing the part Since it is impossible to obtain a forging effect, it is impossible.

In the present invention, a separate additional sub-plate 130 equipped with a hydraulic cylinder 170 generating a large force is mounted on the movable plate 110, so that during the die-casting process of the part, in the state where the mold is closed, in each of the temperature ranges or After the end, the hydraulic cylinder 170 is operated to additionally compress the material to produce a forging effect. The mold 150 on the side of the starting unit is mounted on the mold plate 131, and the mold plate 131 is mounted on the sub-plate 130 through the hydraulic cylinder 170. The hydraulic cylinder 170 mounted on the subplate 130 is composed of one or more, and each cylinder can be implemented in various shapes such as a circular or angular piston, and the size of each cylinder and the size of the operating pressure depend on the size of the part to be molded. Depends on size and material.

In order to carry out the method of the present invention, the structure of the mold must also be designed in a form suitable for the process capable of producing the forging effect, which is configured so that the left and right molds can slide with each other, so that the molds 150 and 160 are given priority during die casting After sealing and injecting the molten metal material, the hydraulic cylinder is operated to move one side of the mold by a certain displacement to the position where the shape of the final part is determined, thereby obtaining a forging effect by additionally compressing the part.

When the mold is further moved to the final position, the cavity becomes smaller and the volume of the injected material (200) decreases accordingly, resulting in excess material (230). It is pushed out through a slit or hole (240) and removed in a subsequent trimming process (230).

If the technology proposed in the present invention is applied, it is possible to mold parts with excellent mechanical properties such as strength, toughness, and wear resistance, which are difficult to obtain from parts molded by conventional die casting, so that the application range of molded parts is subject to high stress. It is very likely to be applied to the production of parts necessary for recent electric vehicles, as it can be expanded to potential areas such as axes, arms, or knuckles of automobiles, and can be reduced in weight due to excellent mechanical properties.

Claims (9)

In the method of forming a part by die casting technology,
(i) In a normal die casting process using left and right or top and bottom molds, one mold is provided so that one mold can slide into the other mold,
(ii) the left and right or top and bottom molds are positioned so as to form a cavity for accommodating molten metal, and the cavity is positioned so as to be larger than the volume of the final part to be produced,
(iii) injecting molten metal into the cavity;
(iv) After the injected molten metal material starts to solidify, one mold is further advanced to the other mold side so that the shape of the final part is formed, so that the structure of the solidified material is densified, so that the same die casting is performed simultaneously or continuously. A die casting method with a forging effect added, characterized in that it is possible to produce a part having excellent mechanical properties by making an additional forging effect before taking the part out of the mold.
Sub-plates 130 and 140 are formed on the left and right or upper and lower plates 110 and 120 of the die-casting device, and one or more hydraulic cylinders 170 capable of generating a required amount of force are installed in the sub-plates, and mold plates 131 and 140 are installed thereon. It is installed and a mold is mounted on it to control the cylinder in the plate and sub-plate to move by the required amount at the required process point during the die-casting process, compressing the material before taking out the die-casting part. Characterized in that forging effect is added Die casting equipment with forging effect added. The method of claim 1,
Step (iv) is a die casting method with a forging effect, characterized in that it is performed several times at a temperature above the recrystallization temperature of the molten metal material or at a temperature below recrystallization. According to claim 1 or 2,
In step (iv), the first forging step is performed by advancing the mold to an intermediate position before the final position in a state where the position of the mold is larger than the volume of the part to be finally molded, and the second forging step is performed by advancing the mold to the final position. A die casting method with added forging effect, characterized in that it consists of two steps of performing steps and the forging process is performed once or several times in each step. The method of claim 3,
A die casting method with a forging effect, characterized in that the temperature of the molten metal material in the first forging step is higher than the recrystallization temperature, and the temperature of the molten metal material in the second forging step is lower than the recrystallization temperature. A die casting apparatus for performing the method of claim 1,
Subplates 130 and 140 are provided on the left and right or upper and lower plates 110 and 120 of the die casting device, respectively, and one or more hydraulic cylinders 170 are provided in the subplate, and a mold plate for mounting a mold on the subplate ( 131,140) is provided, and the die casting device with added forging effect, characterized in that for controlling the mold plate to move by operating the hydraulic cylinder during the die casting process.
(As a mold for die casting for performing the method of claim 1,)
After moving the mold to the position where the molten metal material is injected in the die casting process, one mold is configured to additionally move (sliding) into the other mold and enter, and in the die casting process, when the molten metal is injected in step (iii) Or, in step (iv), a slit or hole that enables the discharge of surplus material that may occur during the further advancement of one mold is provided on the outside of one mold or the other mold. Die casting mold with forging effect added.
As a die casting device,
Subplates 130 and 140 are provided on the left and right or upper and lower plates 110 and 120 of the die casting device, respectively, and one or more hydraulic cylinders 170 are provided in the subplate, and a mold plate for mounting a mold on the subplate ( 130 and 140) are provided to control the mold plate to be moved by operating a hydraulic cylinder during the die casting process.
in claim 7
The die-casting apparatus, characterized in that the mold is configured so that one mold can additionally move (sliding) into the other mold after moving the mold to the position where the molten metal material is injected.
The method of claim 8,
The mold is a die-casting apparatus, characterized in that a slit or hole that enables the discharge of surplus material that may occur in the die-casting process is provided on the outside of one mold or the other mold.

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