JP2002113564A - Metallic mold for forming low melting point metal product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic mold for forming a low melting point metal product in which the low melting point metal product without developing defective formation, such as flow mark, short shot, casting flash, can be formed in a short forming cycle. SOLUTION: This metallic mold is constituted of a fixed side insert (2) fitted to a fixed mold (1), a movable side insert (22) fitted to a movable mold (20) and a first and a second side inserts (31, 32). The first and the second inserts (31, 32) are fitted to the periphery of a cavity. Then, the fixed side insert and the movable side insert are constituted of titanium alloy, and the first and the second side inserts (31, 32) are constituted of a copper alloy. Further, these inserts (2, 22, 31, 32) are independently controlled to each temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a fixed nest attached to a fixed mold and a movable nest attached to a movable mold, and a low melting point metal is provided on the parting line side of these nests. The present invention relates to a mold for molding a low melting point metal product having a cavity for molding the product.

[0002]

2. Description of the Related Art Magnesium alloys, aluminum alloys,
Low melting point metal products made of zinc alloy, copper alloy, lead alloy, etc. are formed by die casting, injection molding, etc., and FIG. 2 shows an example of a mold used for implementing such a forming method. Have been. That is, the conventional molding die shown in FIG. 2A generally includes a fixed nest 51 attached to a fixed mold 50 and a movable nest 51 attached to a movable mold 52. 53. These nests 51 and 53 are generally made of a high heat-resistant material, and a cavity 55 for molding a metal product is formed on the parting line P ′ side. Therefore, a low melting point metal product can be formed as follows. The movable mold 52 is opened at predetermined intervals from the mold clamping state shown in FIG. At this time, the movable mold 52 is guided by the guide pins 56. A water-soluble release agent is sprayed on the surface of the cavity 55 with the mold open. The compressed air is sprayed to evaporate the excess release agent.
Next, the movable mold 52 is clamped to the fixed mold 50.
Then, the cavity 55 is constituted by the fixed side insert 51 and the movable side insert 53 as shown in FIG. Therefore, the molten low melting point metal material is injected from the injection nozzle 58 of the injection molding machine 57. The low melting point metal material is filled into the cavity 55 through the sprue 60, the runner 61 and the side gate 62. After cooling and solidification, the movable mold 52 is opened by a predetermined amount. Then, the ejector pins 63 to 66 protrude, and the low melting point metal product protrudes from the movable side insert 53. As a result, a low-melting metal product is obtained. Hereinafter, a low melting point metal product is obtained in the same manner.

[0003]

As described above, a low-melting metal product can be formed by a conventional mold, but it has various disadvantages. For example, as shown in FIG. 3A, in the step B of opening the movable mold 52 to take out the low melting point metal product and spraying the release agent, the fixed side and movable side inserts 51 and 53 are formed. The surface temperature is lower by 30 to 40 ° C. than the temperature in the mold closing injection step A. This lowered temperature requires a recovery step C of about 6 to 8 minutes even when the heaters 59, 59,... Of the fixed and movable nests 51, 53 are energized, which hinders an improvement in productivity. Therefore,
Generally, the process proceeds to the next step before the completion of the recovery step C for recovering to a predetermined temperature. By the way, since the low melting point metal material generally has high thermal conductivity, when it comes into contact with the fixed-side and movable-side inserts 51 and 53 having a low thermal conductivity and high thermal conductivity, the material is rapidly cooled and the solidification speed is increased. as a result,
Poor flow results in molding defects such as hot lines and short shots. It is considered that such molding defects can be eliminated by increasing the injection speed or the filling speed to some extent. However, when the injection speed is increased, rapid braking control just before the completion of filling is required. Can not apply sufficient pressure, causing short shots. It also causes burrs. In particular, when the low-melting point metal material is a molten magnesium alloy, the viscosity is extremely low. Therefore, if the rapid brake control is mistaken, the parting of the fixed-side and movable-side inserts 51 and 53 which are clamped by the normal clamping force is performed. Line P '
The burr is generated by entering a very small gap.

However, according to Japanese Patent Application Laid-Open No. H11-77240, as shown in FIG.
A mold in which the surface of a cavity 69 formed along the parting line P ′ 8 is covered with heat insulating layers 70, 70 has been proposed. According to this mold, the heat insulating layers 70, 7
Since 0 is provided, the cooling and solidification of the molten metal flowing into the cavity 69 is delayed, and as a result, the filling distance is extended, and effects such as reduction of molding defects such as nests and hot lines are recognized. . However, in order to change the shape of the cavity 69, the heat insulating layers 70, 70 formed by thermal spraying or ceramics inorganic electrolytic plating are once peeled off, formed into a predetermined shape, and then again sprayed or ceramics inorganic electrolytic plating. Therefore, the period for changing the cavity may be lengthened and the cost may be increased. Further, the heat insulating layers 70 and 7
Since the temperature of 0 cannot be controlled, it is expected that the cooling and solidification rate cannot be controlled and that an appropriate molding cycle cannot be set. The present invention has been made in view of the conventional problems as described above, and has an object to provide a molding die for a low-melting metal product that can be molded at a low cost with a high-quality low-melting metal product. Specifically, it is an object of the present invention to provide a molding die for a low-melting metal product that can be molded in a short molding cycle without a molding defect such as hot water, short shot, and burrs. . It is another object of the present invention to provide a mold for molding a low melting point metal product which can change the shape of a cavity for molding the low melting point metal product in a short period of time at low cost.

[0005]

The above objects of the present invention are as follows.
The nests attached to the fixed mold and the movable mold are made of a material having a thermal conductivity of less than 10 w / mk, and the nests are formed with cavities for molding low melting point metal products, and the temperature of these nests is reduced. This is achieved by configuring to control independently. That is, in order to achieve the above object, the invention according to claim 1 of the present application comprises a fixed nest attached to a fixed mold and a movable nest attached to a movable mold. A mold for forming a low melting point metal product on the parting line side of the mold, wherein the fixed side insert and the movable side insert have a thermal conductivity of 1;
It is made of a material of 0 w / mk or less and is configured so that the temperature is controlled independently of a system for controlling the temperature of other components of the mold. The invention according to claim 2 comprises a fixed nest attached to a fixed mold, a movable nest attached to a movable mold, and a third nest, wherein the fixed nest and the movable nest are combined. A cavity for molding a low-melting metal product on the parting line side is configured, and the third nest is a mold attached around the cavity, and the fixed nest and the movable nest are: The third nest is made of a metal material having a thermal conductivity of 100 w / mk or more, while being made of a material having a thermal conductivity of 10 w / mk or less. According to a third aspect of the present invention, the fixed side nest and the movable side nest according to the first or second aspect are made of a titanium alloy. The fourth aspect of the present invention is the third aspect of the third aspect. The nest is made of a copper alloy, and the invention according to claim 5 is such that the fixed nest and the movable nest according to claim 2 or 3 are independent of a system for controlling the temperature of other components of the mold. 7. The temperature is controlled so that the temperature is controlled.
The temperature of the fixed nest, the movable nest and the third nest is controlled independently of a system for controlling the temperature of other components of the mold. It is configured to be.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to molding examples using a molding die and an injection molding machine for magnesium alloy products. As shown in FIG. 1, the mold according to the present embodiment is removably attached to the fixed mold 1 and the movable mold 20, similarly to the fixed mold 1. Movable nest 22
And first and second side nests 31 and 32 disposed around these nests 2 and 22. According to the present embodiment, the fixed mold 1 and the movable mold 20 are made of conventionally known carbon steel. However, the fixed nest 2 and the movable nest 22 are as shown in Table 1. It is made of a titanium alloy having properties and a small thermal conductivity of 7.5 w / mk. The first, second and third
Are made of a copper alloy having a large thermal conductivity of 130 w / mk.

[0007] A locating ring 8 is attached to a substantially central portion of the fixed-side mounting plate 7 to which the fixed mold 1 is attached, and a sprue bush 9 is provided on the fixed mold 1 so as to face the locating ring 8. I have. The sprue bush 9
It penetrates the fixed side insert 2. A bush core 23 is attached to the movable die 20 so as to face the sprue bush 9. An ejector pin 27 is provided corresponding to the sprue bush 9. This allows
In the clamped state shown in FIG. 1A, the sprue bush 9, the bush core 23 and the ejector pin 27
The sprue 6 is formed by the tip of the sprue. This sprue 6
Communicates with a runner 5 and a side gate 4 described later. The fixed side insert 2 described above is removably attached to the mold part surface of the fixed mold 1 thus configured, and a concave portion is formed on the fixed side of the parting line P. A part of the side gate 4 and a part of the runner 5 is formed in one movable side portion of the concave portion in cooperation with a movable side insert 22 described later in detail. Fixed type 1
Are provided with heaters h, h,... Composed of heaters, etc., but the fixed nest 2 is also provided with a heater, for example, an electric heater whose heat generation temperature is controlled independently of the heaters h, h,. Are provided.

The movable mold 20 is mounted on the movable mounting plate 21 in a known manner. Then, a plurality of ejector pins 24-
27 is provided so as to be freely inserted and removed. The ends of these ejector pins 24 to 27 are fixed by two ejector plates 28. Also, guide bushes 29, 29,... Are mounted on the side of the movable mold 20, and the guide pins 11, 11,. The movable mold 20 is opened and closed. Note that the movable die 20 is also provided with heating elements h, h,. The movable side insert 22 described above is detachably attached to the mold part surface of the movable mold 20 configured as described above, and a core is formed on the fixed side of the parting line P. A cavity 3 for molding a magnesium alloy product is constituted by the core and the recess of the fixed side insert 2 described above. Cavity 3
It communicates with the aforementioned sprue 6 via a side gate 4 and a runner 5. The movable side insert 22 also has a movable mold 20.
The heating elements H2, H2,..., For example, composed of electric heaters, whose heating temperatures are controlled independently of the heating elements h, h,.

The first side insert 31 is removably attached to the fixed mold 1 and comprises three side inserts 31a to 31c. And these three
As shown in FIG. 1B, the three side inserts 31a to 31c are three sides far from the sprue 6, more precisely three sides far from the side gate 4, of the four sides of the cavity 3. Is provided so as to surround the. These three
As described above, the side nests 31a to 31c
Since the molten magnesium is made of a copper alloy having high thermal conductivity, the molten magnesium injected and filled into the cavity 3 is solidified around the cavity 3 at an early stage, and the generation of burrs is suppressed. The three side nests 31 arranged in this way
a to 31c are also heating elements H composed of electric heaters whose heating temperatures are controlled independently of the heating elements h, h,.
1 ′, H1 ′,... Are provided.

The second side insert 32 is provided on the movable mold 20 side, is configured substantially in the same manner as the first side insert 31, and is independently controlled.
2 ′, H2 ′,... Are also provided. In the closed state of the mold, the above-described ejector pin 24 penetrates through the movable side insert 12 and the second side insert 32, and the distal end thereof is constituted by first and second side inserts 31, 32. Ejector pin 2 located on the surface of overflow 33
5 and 26 are respectively located on the surface of the cavity 3.

The injection molding machine 40 includes a heating cylinder 41 as is well known in the art. An injection nozzle 42 is attached to the tip of the heating cylinder 41, and a screw that can be driven in the rotation direction and the axial direction is provided inside the injection nozzle 42.

Next, an example of molding using the above mold will be described. The screw of the injection molding machine 40 is driven to rotate, and the magnesium alloy is melted and measured in a conventionally well-known manner. At this time, the temperature control device provided on the outer peripheral portion of the heating cylinder 41 is driven to heat the heating cylinder 41 to a temperature higher than the solidus temperature of the magnesium alloy. It is also possible to control the temperature to be lower than the phase line temperature. As a result, the generation of dendrites in the molten alloy material is prevented, and the thixotropic state is maintained, and the molten metal is weighed in the heating cylinder 41 as conventionally known.

The heating elements H1 and H1 are controlled so that the temperatures of the fixed nest 2 and the movable nest 22 are, for example, 180 to 230 ° C.
1,..., H2, H2,. Also,
The heating elements H1 ′ and H1 ′ are arranged such that the temperatures of the first and second side nests 31 and 32 are 100 to 150 ° C. lower than the temperatures of the fixed side nest 2 and the movable side nest 22 by about 80 ° C.
, H2 ', H2',... Are set.

With the movable mold 20 opened, a conventionally known water-soluble release agent is sprayed on the surface of the cavity 3. Wait for the excess of the sprayed release agent to evaporate. At this time, barge is performed with compressed air as needed to promote evaporation. The movable mold 20 is clamped to the fixed mold 1. Then, as shown in FIG. 1A, the cavity 3 is constituted by the fixed side insert 2 and the movable side insert 22. The injection nozzle 42 of the injection molding machine 40 is made to touch the sprue bush 9, and the screw is driven in the axial direction to inject the measured molten magnesium alloy. The molten magnesium alloy is filled into the cavity 3 through the sprue 6, the runner 5, and the side gate 4.

At this time, since the cavity 3 is made of a titanium alloy, the thermal conductivity of the molten magnesium alloy is large, but the molten magnesium alloy is cooled down gently and the solidification speed is reduced. Thereby, every corner of the cavity 3 is densely filled. At this time, the temperatures of the fixed side insert 2 and the movable side insert 22 are maintained at relatively high temperatures suitable for molding, as shown in FIG. 3B. In addition, since the first and second side inserts 31 and 32 are made of a copper alloy having a low temperature and a high thermal conductivity, the molten magnesium alloy to be filled will flow out of a very small gap of the parting line P. Also, the heat is radiated toward the low-temperature first and second side inserts 31 and 32 and solidifies. This allows
Burrs are suppressed. The holding pressure is applied for a predetermined time, and the movable mold 20 is opened after solidification. At this time, the magnesium alloy product arrives at the core of the movable side insert 22 and is opened according to the shape and the like of the magnesium alloy product. When the movable mold 20 is opened by a predetermined amount, the ejector plate 28
Is driven to eject the ejector pins 24 to 27 to obtain a high quality magnesium alloy product free from hot water, short shots, and the like. Hereinafter, molding is performed in the same manner.

When the shape, size, and the like of the magnesium alloy product to be formed are changed, necessary inserts are removed, and the surface of the cavity 3 is processed by cutting or the like. And then
Attach. Or, replace it with a nest that is prepared separately. Thereby, a magnesium alloy product having a desired shape or size can be formed as described above.

It is clear that the present invention can be implemented in various forms without being limited to the above embodiment. For example, it is clear that a low melting point metal material can be formed in the same manner by using a semi-molten magnesium alloy instead of a molten magnesium alloy. It is also apparent that a low-melting metal product can be formed in the same manner from a low-melting metal material such as an aluminum alloy, a zinc alloy, a copper alloy, and a lead alloy other than the magnesium alloy. Further, in the above embodiment, the mold is described as a mold applied to an injection molding machine, but it is apparent that the mold can be applied to a die casting method.

Regarding the material of the nest, the fixed nest and the movable nest may be made of any material other than titanium alloy, as long as the material has a thermal conductivity smaller than that of the fixed and movable molds. As also shown in FIG. 1, it is desirable to constitute from a material having a thermal conductivity of less than 10 w / mk. The first and second side inserts may be made of any material other than copper alloy as long as the material has a thermal conductivity larger than that of the fixed type and the movable type.
It is desirable to use a metal material larger than / mk. Further, depending on the shape and size of the cavity, it is apparent that the material can be used at different temperatures even if the material of the fixed side insert and the movable side insert is different from each other. Furthermore, in this embodiment, the first and second side inserts are provided on the fixed and movable parting line sides, respectively, but are made of a metal material having a high thermal conductivity such as a copper alloy. In this case, it is apparent that the same effect can be obtained even if it is provided on either the fixed parting line side or the movable parting line side. In addition, the magnesium alloy AZ91D in Table 1 shows the physical property values of the compact.

[0019]

As described above, according to the present invention, the fixed nest attached to the fixed mold and the movable nest attached to the movable mold have a thermal conductivity of 10 w / mk.
Since it is composed of the following materials, the solidification rate of the low melting point metal material when filling the cavity is gentle and small. As a result, an effect peculiar to the present invention is obtained in that the fluidity of the low-melting metal material is maintained, and a high-quality low-melting metal product having no molding defects such as hot lines and short shots is obtained. As described above, since the fluidity is maintained, it is not necessary to perform high-speed filling. Therefore, generation of burrs due to high-speed filling is suppressed. Further, according to the present invention, the fixed nest and the movable nest are configured such that the temperature is controlled independently of the system for controlling the temperature of the other components of the mold. Is maintained at an appropriate temperature, and the effect of improving productivity is also obtained. Furthermore, since the nest forming the cavity is entirely made of a material having a thermal conductivity of 10 w / mk or less,
The size, shape, and the like of the cavity can be easily changed by cutting or the like. According to another aspect of the present invention, the fixed nest attached to the fixed mold and the movable nest attached to the movable mold have a thermal conductivity of 10 w / m.
k, and the third nest attached around the cavity formed by these nests is made of a metal material having a thermal conductivity of 100 w / mk or more. In addition, the low-melting metal material flowing away from the periphery of the cavity, that is, from the parting line, is cooled and solidified, whereby the effect of further suppressing the generation of burrs is obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a mold for molding a low-melting metal product according to an embodiment of the present invention, in which (a) is a sectional view showing a state in which the mold is closed, and (b) is (a). 5 is a plan view of the fixed type as viewed from the parting line side.

FIG. 2 is a diagram showing a conventional mold in a closed state, in which (a) is a cross-sectional view showing a first conventional mold and (b) another conventional mold.

3A and 3B are diagrams showing a temperature change state of a mold, in which FIG. 3A shows a change in each conventional molding cycle, and FIG. 3B shows a mold temperature suitable for casting. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fixed type 2 Fixed side nest 3 Cavity 20 Movable type 22 Movable side nest 31 First
Side nesting 32 Second side nesting H1, H2, H1 ', H2' Heating body (heater)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22C 9/06 B22C 9/06 Q

Claims (6)

[Claims] 1. A cavity for molding a low-melting point metal product on a parting line side of a fixed side nest attached to a fixed mold and a movable side nest attached to a movable mold. Wherein the fixed side insert and the movable side insert have a thermal conductivity of 10 watts.
/ Mk, wherein the temperature is controlled independently of a system for controlling the temperature of other components of the mold. Mold. A fixed nest attached to the fixed mold, a movable nest attached to the movable mold,
A cavity for molding a low melting point metal product is formed on the parting line side of the fixed side nest and the movable side nest, and the third nest is mounted around the cavity. The fixed side nest and the movable side nest have a thermal conductivity of 10 watts.
/ Mk or less, and the third
Wherein the nest is made of a metal material having a thermal conductivity of 100 w / mk or more. 3. A mold for molding a low melting point metal product, wherein the fixed side insert and the movable side insert according to claim 1 or 2 are made of a titanium alloy. 4. A mold for molding a low melting metal product wherein the third nest according to claim 3 is made of a copper alloy. 5. The molding of a low melting point metal product in which the fixed nest and the movable nest according to claim 2 or 3 are controlled in temperature independently of a system for controlling the temperature of other components of the mold. Mold. 6. The fixed nest, the movable nest and the third nest according to claim 2 or 3, wherein the temperature is controlled independently of a system for controlling the temperature of other components of the mold. Mold for low melting metal products.