KR102457835B1 - Injection mold having heating layer and manufacturing method thereof - Google Patents

Abstract

An injection mold having a heating layer according to the present invention includes: a first mold having a first cavity formed in a core portion; a first insulating layer provided on the first mold; a first heating layer provided on the first insulating layer; a plurality of electrodes having one end connected to the first heating layer; and a first protective layer provided to cover the first heating layer and the electrode, wherein the first heating layer includes titanium dioxide.

Description

Injection mold with heating layer and manufacturing method thereof

The present invention relates to an injection mold having a heating layer and a method for manufacturing the same. More specifically, the present invention relates to an injection mold having a heating layer capable of manufacturing an injection molded article by controlling the temperature of the mold in the process of injecting a synthetic resin or molten metal, and a manufacturing method thereof.

In general, when various types of molded products are manufactured using synthetic resins or metals, injection molds are mainly used. Synthetic resin dissolved at high temperature is introduced into a mold and then extruded to manufacture various types of molded products.

Molded products using injection molds have the advantages of excellent quality, precise control of dimensions, high production speed, mass production, and low manufacturing cost.

However, during injection molding, when two or more flow stages are joined and fused, a weld line is generated, resulting in surface defects and reduced appearance. In order to overcome this, a molding method in which the temperature of the injection mold is heated higher than the melting temperature of the resin to be molded has been developed.

As a method of controlling the temperature of the injection mold, a heater heating method that directly attaches a heater to the mold and a steam heating method that heats the mold by introducing hot steam by forming a steam channel in the mold were introduced. This increases the restriction on the injection mold apparatus, and since it is difficult to maintain a uniform temperature in the mold, it is difficult to apply to a molding process having a large area such as a TV panel case.

The heater heating method consumes excessive power, and in the case of steam heating, temperature control is difficult, and a separate cooling step is required, thereby increasing the process cost.

Therefore, there is an urgent need to develop an injection mold equipped with a heating layer capable of injection molding a high-quality large-area molded article by closely controlling the temperature of the mold in an existing temperature-controlled injection mold and a method for manufacturing the same.

As a background art of the present invention, an injection molding mold heating apparatus is disclosed in Korean Patent Application Laid-Open No. 10-2011-0067669.

An object of the present invention is to provide an injection mold that is provided with a heating layer in the injection mold to closely control the temperature of the injection mold to manufacture a high-quality injection molded article.

Another object of the present invention is to provide a method of manufacturing an injection mold having a heating layer capable of manufacturing a high-quality injection molded article.

All of the above and other objects of the present invention can be achieved by the present invention described below.

1. One aspect of the present invention relates to an injection mold provided with a heating layer.

The injection mold may include a first mold in which a first cavity is formed in a core portion;

a first insulating layer provided on the first mold;

a first heating layer provided on the first insulating layer;

a plurality of electrodes having one end connected to the first heating layer; and

Includes; a first protective layer provided to cover the first heating layer and the electrode;

The first heating layer includes titanium dioxide.

2. In the first embodiment, a second formed to correspond to the first mold, at least a portion is in close contact with the first mold, and a second cavity is formed to form an injection space closed with the first cavity mold;

a second insulating layer provided on the second mold;

a second heating layer provided on the second insulating layer;

a plurality of electrodes connected to the second heating layer; and

Further comprising; a second protective layer provided to cover the second heating layer and the electrode,

The second heating layer may include titanium dioxide.

3. In the above 1 or 2 embodiments, it is formed to correspond to the first mold, at least a portion is in close contact with the first mold, and a third cavity is formed to form an injection space closed with the first cavity a third mold; and

It may further include; a third insulating layer provided on the third mold.

4. In the above 1 or 2 embodiments, the first heating layer and the second heating layer are those in which a transition metal and a transition metal oxide are dispersed in a titanium dioxide substrate, and the transition metal and the transition metal oxide are dispersed in 100 parts by weight of titanium dioxide. 30 parts by weight or less may be included.

5. In the 4th embodiment, the transition metal may be one or more of nickel (Ni), cobalt (Co), zinc (Zn), chromium (Cr), tungsten (W), and molybdenum (Mo).

6. In the above 1 or 2 embodiments, the first heating layer and the second heating layer may have an average thickness of 10 to 500㎛.

7. In the above 1 or 2 embodiment, the deviation of the temperature measurement value at at least three different points when 220V voltage is applied to the first heating layer and the second heating layer may be less than 10%.

8. The embodiment of any one of 1 to 3, wherein the first insulating layer, the second insulating layer, and the third insulating layer are aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), boron nitride (BN) ), YAG (Y ₃ Al ₅ O ₁₂ ), and magnesium oxide (MgO) may include at least one oxide.

9. In any one of embodiments 1 to 3, the first insulating layer, the second insulating layer, and the third insulating layer may exhibit a resistance value of 900 to 1,000 MΩ when a voltage of 1,000 V is applied.

10. In any one of embodiments 1 to 3, the depth of the injection space may be 1 mm or less.

11. Another aspect of the present invention relates to a method for manufacturing an injection mold having a heating layer. The injection mold manufacturing method provided with the heating layer is

(a) forming a cavity in the core portion of the mold;

(b) forming an insulating layer on the mold;

(c) forming a heating layer comprising titanium dioxide on the insulating layer;

(d) forming a plurality of electrodes in contact with the heating layer; and

(e) forming a protective layer on the heating layer and the electrode; includes.

12. In the 11th embodiment, the heating layer is a titanium dioxide substrate in which a transition metal and a transition metal oxide are dispersed, and the transition metal and the transition metal oxide are included in an amount of 30 parts by weight or less in 100 parts by weight of the titanium dioxide, It may be formed by plasma spray coating.

The present invention is an injection mold having a heating layer capable of close temperature control, and an injection molded product without molding defects can be manufactured. It is possible, and the quality of the molded product can be greatly improved by directly heating the molten material. The heating layer is formed by thermal spray coating, so there is no restriction according to the shape of the injection mold or cavity, and it is possible to manufacture large-area injection molded products with a thickness of 1 mm or less by adjusting the depth of the cavity in the mold core.

In addition, it is possible to manufacture injection molds having various shapes by forming a heating layer with a heating composition capable of thermal spray coating.

1 is a side cross-sectional view of an injection mold provided with a heating layer including a first mold according to an embodiment of the present invention.
FIG. 2 is a plan view of the injection mold according to FIG. 1 .
3 is a side cross-sectional view of an injection mold provided with a heating layer including a second mold according to an embodiment of the present invention.
FIG. 4 is a plan view of the injection mold according to FIG. 3 .
5 is a side cross-sectional view of the injection mold in a state in which the first mold and the second mold are combined according to an embodiment of the present invention.
6 is a side cross-sectional view of an injection mold including a third mold according to an embodiment of the present invention.
7 is a side cross-sectional view of the injection mold in a state in which the first mold and the third mold are combined according to an embodiment of the present invention.
8 is a process flow diagram of a method for manufacturing an injection mold according to another aspect of the present invention.
9 is a photograph illustrating temperature measurement of a thermal imaging camera for evaluating the heating performance of an injection mold provided with a heating layer according to an embodiment of the present invention.
10 is a graph showing the amount of heat generated when a voltage of 220V is applied to an injection mold having a heating layer according to an embodiment of the present invention for 12 seconds.
11 is a graph showing the amount of heat generated when a 380V voltage is applied for 5 seconds to an injection mold having a heating layer according to an embodiment of the present invention.
12 is a graph showing three different temperatures for each time when 220V is applied to an injection mold having a heating layer according to an embodiment of the present invention.
13 is an enlarged photograph of the surface of the molded article after injection molding according to the exothermic temperature in the injection mold according to one embodiment of the present invention.
14 is a photograph of measuring the thickness of the injection molded article injected from the injection mold according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the following drawings are provided only to help the understanding of the present invention, and the present invention is not limited by the following drawings. In addition, since the shape, size, ratio, angle, number, etc. disclosed in the drawings are exemplary, the present invention is not limited to the illustrated matters.

Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless specifically stated otherwise.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

When the positional relationship of two parts is described with 'on', 'on', 'on', 'next to', etc., between the two parts unless 'directly' or 'directly' is used One or more other portions may be located.

Positional relationships such as 'upper', 'top', 'lower', 'bottom' are only described based on the drawings, and do not represent absolute positional relationships. That is, the positions of 'upper' and 'lower' or 'upper' and 'lower' may be changed according to the observed position.

Hereinafter, an injection mold having a heating layer according to an embodiment of the present invention will be described with reference to the drawings.

1 is a cross-sectional side view of an injection mold provided with a heating layer including a first mold according to an embodiment of the present invention, FIG. 2 is a plan view of the injection mold according to FIG. 1, and FIG. 3 is a sphere of the present invention A side cross-sectional view of an injection mold having a heating layer including a second mold according to an example, FIG. 4 is a plan view of the injection mold according to FIG. 3, and FIG. 5 is a first mold and a first mold according to an embodiment of the present invention. 2 is a cross-sectional side view of the injection mold in a state in which the mold is coupled, FIG. 6 is a side cross-sectional view of the injection mold including a third mold according to an embodiment of the present invention, and FIG. It is a side cross-sectional view of the injection mold in a state in which the first mold and the third mold are combined.

1 to 5 , the injection mold provided with the heating layer includes a first mold 100 , a first insulating layer 200 , a first heating layer 300 , a plurality of electrodes 400 , and a first protection. layer 500 .

The first mold 100 has a first cavity 110 formed in a core portion to provide a space in which the first heating layer 300 can be disposed.

Specifically, the first cavity 110 is formed to a predetermined depth so that even when the first insulating layer 200 and the first heating layer 300 are stacked, a certain space is formed in the first cavity 110, and the molten resin flows in. can be

The first mold 100 is not particularly limited as long as it has a strength capable of injection molding by pressing the molten resin, and for example, it is preferably made of aluminum alloy steel or tool steel containing carbon.

In injection molding, in which synthetic resin is melted and injected into the mold, when it is injected at a lower temperature than the molten material, defects in molded products such as flow marks, weld lines, and jetting may occur. Because it can be generated, a mold heater is attached when designing a mold, or a steam channel through which hot steam is introduced is provided. In this case, there is a problem in that the volume of the mold increases and the mold structure becomes complicated.

The first mold 100 is provided with a first heating layer 300 that can directly heat the pressurized surface where the molten resin is introduced and is molded directly on the first mold 100 to effectively reduce the volume of the mold. Since a complicated structure for preventing defects such as flow marks is not required even when designing a mold, the degree of freedom in mold design is increased, and defects in molded products can be effectively prevented.

The first mold 100 may be provided with a first heating layer 300 by forming a first cavity 110 of a predetermined depth in the mold itself, and even if the shape of the mold is deformed and provided in various forms, the first Since the heating layer 300 can be provided, the first mold 100 may have a curved shape, and the shape is not particularly limited.

Since the first mold 100 can be provided with the first heating layer 300 only by surface processing such as etching, a relatively expensive mold is not replaced, and the mold used in the injection process is processed as it is to form the first cavity. If only 110 is formed, the first heating layer 300 can be provided and the cost of manufacturing the mold can be greatly reduced.

The first insulating layer 200 is provided inside the first cavity 110 .

In the first mold 100 , the first cavity 110 may be formed and the first insulating layer 200 may be provided.

The first insulating layer 200 may prevent current leakage from the first mold 100 by preventing the flow of current between the first mold 100 and the first heating layer 300 , and It is possible to prevent the heat generated in the first heating layer 300 from being transferred to the first mold 100 , and it is possible to increase the long-term stability of the first mold 100 .

Specifically, the first insulating layer 200 includes aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), boron nitride (BN), YAG (Y ₃ Al ₅ O ₁₂ ), and magnesium oxide (MgO). It may include one or more oxides.

Since this type of oxide can form ceramics by thermal spray coating, spray coating, or printing method, the first insulating layer 200 can be formed as a passivation layer. The compound of the above type may be formed into a ceramic while forming an oxide during thermal spray coating to increase insulation and heat insulation.

The first insulating layer 200 may be formed to a thickness of 10 to 500 μm.

When the first insulating layer 200 is formed to a thickness within the above range, the energization of the first mold 100 can be prevented, and when a second mold 600 to be described later is provided, the second mold 600 and Since the energization phenomenon can also be effectively prevented, the safety of using the injection mold can be greatly increased.

The first insulating layer 200 exhibits an adhesive force between the first mold 100 and the first heating layer 300 so that the first heating layer 300 is firmly attached to the first mold 100 . It can be maintained in a constant state.

In one embodiment, the first insulating layer 200 may exhibit a resistance value of 900 to 1,000 MΩ when a voltage of 1,000 V is applied.

Since the first insulating layer 200 forms an insulating layer by exhibiting a resistance value within the above range, it is effective to prevent leakage current from being issued to the first mold 100 even when the voltage applied to the first heating layer 300 is increased. can be prevented

The first heating layer 300 may be provided on the first insulating layer 200 .

The first heating layer 300 may be heated by receiving electrical energy from the electrodes 400 connected to both ends.

The first heating layer 300 includes titanium dioxide.

The first heating layer 300 is formed by plasma spray coating, and specifically, since the titanium dioxide has a high melting point, it is very preferable to form a plasma spray coating that can form a ceramic with a flame of 1,000° C. or more among the thermal spray coatings. do.

In one embodiment, in the first heating layer 300, the transition metal and the transition metal oxide may be included in 100 parts by weight of the titanium dioxide in an amount of 30 parts by weight or less.

For example, the transition metal and the transition metal oxide may be included in an amount of 20 parts by weight or less, more preferably 11 parts by weight or less.

When the transition metal and transition metal oxide are mixed in 100 parts by weight of the titanium dioxide in an amount of 30 parts by weight or less, the first heating layer 300 is based on titanium dioxide and the transition metal and the transition metal oxide are uniformly dispersed to generate the first heat A layer 300 may be formed.

When the transition metal and the transition metal oxide are included, heat is uniformly possible over the entire surface when the first heating layer 300 is heated, so the area of the first heating layer 300 is effectively increased to produce a large-area molded article. Injection is possible, and it is maintained at a temperature higher than the temperature of the molten object during the injection process, thereby effectively preventing the occurrence of molding defects such as flow masks and weld lines occurring in conventional injection-molded products.

Specifically, the transition metal is at least one of nickel (Ni), cobalt (Co), zinc (Zn), chromium (Cr), tungsten (W), and molybdenum (Mo), and the type of transition metal is plasma thermal spraying. It is coated to form a transition metal oxide and is uniformly dispersed in the first heating layer 300 to effectively increase the temperature increase rate of the heating layer.

The titanium dioxide and the transition metal are in powder form, and it is easy to secure fluidity in the plasma spray coating process, and it is possible to apply the titanium dioxide and the transition metal very uniformly to the upper portion of the first insulating layer 200 and control the thickness.

The first heating layer 300 can control the heating temperature range by adjusting the resistance by adjusting the thickness, and in the case of including oxide, structural stability is very high than when the heating layer is formed with a metal element alone, so Since it does not change when exposed, it can greatly increase the long-term operational stability of the injection mold.

Each of the first heating layers 300 may have a thickness of 10 to 500 μm.

The first heating layer 300 is provided within the above range to reduce the resistance in the first heating layer 300 to lower the voltage for heating, and to maintain the adhesive force with the first insulating layer 200, injection It can increase the life of the mold and increase the efficiency during long-time operation.

Specifically, when the thickness of the first heating layer 300 is less than 10㎛, the resistance of the heating layer is increased to 100Ω or more, and a high voltage exceeding 380V is required for heat generation, and when it exceeds 500㎛, the resistance of the heating layer is 5Ω or less. A current of 100A or more is required to form a resistor to generate heat, which is undesirable.

The thickness of the first heating layer 300 may be adjusted in consideration of the melting temperature of the molten material flowing in within the above range, and it is possible to adjust up to a preset heating temperature according to the thickness of the first heating layer 300 . .

In one embodiment, the deviation of the temperature measurement value at at least three or more different points when 220V voltage is applied to the first heating layer 300 may be less than 10%.

Specifically, the first heating layer 300 is capable of uniform heat generation along the entire surface, and the temperature deviation when measuring the temperature at each different point is less than 10%, specifically 3 to 8%. .

Since the first heating layer 300 is uniformly heated within the above range, various defects such as flow marks of injection-molded products can be prevented, and even if the first heating layer 300 has a large area, uniform heating is possible. It is possible to manufacture a large-area molded article, and for example, a large-area injection-molded article such as a case of a large TV panel can be effectively manufactured without defects.

The first heating layer 300 is rapidly heated when a voltage is applied, and for example, the first heating layer 300 having a heating area of 240 × 175 mm can reach 120° C. within 12 seconds when 220 V voltage is applied. In addition, when 380V voltage is applied, rapid heat generation of 200°C or higher is possible in 1 second, enabling effective injection molding.

The electrode 400 is provided in plurality, and is electrically connected to the first heating layer 300 .

Specifically, the electrode 400 may be electrically connected to both ends of the first heating layer 300 .

The electrode 400 may supply electric energy to heat the first heating layer 300 .

The electrode 400 may include one or more metals of silver (Au), copper (Cu), molybdenum (Mo), and tungsten (W), and may be formed by thermal spray coating or printing.

Specifically, the electrode 400 may be formed to a thickness of 10 to 500 ㎛.

The first protective layer 500 is provided to cover a portion of the first heating layer 300 and the upper electrode 400 .

Specifically, the first protective layer 500 is one of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), boron nitride (BN), YAG (Y ₃ Al ₅ O ₁₂ ), and magnesium oxide (MgO). It contains more than one kind of oxide, and may further contain cellulose, and may be formed by thermal spray coating, spray coating or printing method.

The first protective layer 500 may protect the heating layer and the electrode from the outside, and may exhibit insulation.

Specifically, the first protective layer 500 may be formed to a thickness of 10 to 500 μm, and when provided with a thickness within the above range, supports the first heating layer 300 and the electrode 400 and supports external impact. It can protect from over-contamination, can exhibit electrical insulation, and can reduce the overall manufacturing cost of the injection mold.

In one embodiment, the first protective layer 500 may have a Vickers hardness (HV) of 700 to 900.

The first protective layer 500 is formed to a thickness within the above range to increase hardness, and when the hardness is within the above range, the first heating layer 300 is effectively protected even in the process of injection molding by pressing the molten synthetic resin. can do.

The first mold 100 may be an upper mold or a lower mold of an injection mold. For example, when the first mold 100 is an upper mold, it further includes a lower mold having the same configuration to configure the injection mold. can do.

In one embodiment, the second mold 600 is formed to correspond to the first mold 100 , and moves in a vertical direction so that at least one part is in close contact with the first mold 100 , and the second cavity 620 . ) may be formed to form the first cavity 110 and the sealed injection space 1100 .

The second mold 600 may be disposed under the first mold 100 to constitute a lower mold.

A second insulating layer 700 , a second heating layer 800 , an electrode 900 , and a second protective layer 1000 may be provided on the second mold 600 .

The second mold 600 is the same member as the first mold 100, and a second cavity 620 is formed in a core portion to a predetermined depth, and the second insulating layer 700 and the second heating layer ( 800) can be provided.

The second mold 600 may be formed to correspond to the first mold 100 moving in the vertical direction, and may be in close contact with the first mold 100 to form an injection space 1100 , and at this time, Injection molding can be performed by pressurizing the introduced molten material.

Specifically, in the first mold 100 and the second mold 600 , a first cavity 110 and a second cavity 620 are formed, respectively, and the first cavity 110 and the second cavity 620 are formed. When they face each other and are interviewed, a sealed injection space 1100 can be formed on the inside.

An injection hole 610 is formed in the second mold 600 , and a molten resin or a molten material may be introduced through the injection hole 610 .

When the first heating layer 300 and the second heating layer 800 are heated, the molten material or the molten resin is introduced into the injection space 1100 through the injection hole 610 and is pressurized and injection molded. It is possible to significantly reduce the surface defects of injection molded products.

In one embodiment, the depth of the injection space 1100 may be 1 mm or less.

The depth of the injection space 1100 is formed to be 1 mm or less, so that a thin molded article may be injected and manufactured, for example, a large-area TV case may be injection molded to a thin thickness.

The second insulating layer 700 is provided on the second mold 600 and is the same member as the first insulating layer 200 .

The second heating layer 800 is provided on the second insulating layer 700 and is the same member as the first heating layer 300 .

The electrode 900 is electrically connected to the second heating layer 800 , and has the same structure as the electrode 400 provided on the first insulating layer 200 and has the same structure as the second heating layer 800 . ) to receive external electrical energy and deliver it to the second heating layer 800 , so that the second heating layer 800 can be heated.

The second passivation layer 1000 is the same member as the first passivation layer 500 and may be disposed in the same structure.

The second protective layer 1000 protects the second heating layer 800 and the electrode 900 from the outside, and can exhibit insulation to prevent electrical interference between the first mold 100 and the lower mold. can

Specifically, the second protective layer 1000 may be formed to a thickness of 10 to 500 μm to support and protect the second heating layer 800 and the electrode 900 .

In one embodiment, the second protective layer 1000 may have a Vickers hardness (HV) of 700 to 900.

The first protective layer 500 and the second protective layer 1000 are provided to prevent electrical interference between the first mold 100 and the second mold 600, and to prevent electrical leakage to the injection mold It can increase safety when used.

In one embodiment, the first mold 100 may further include a third mold 1200 .

The third mold 1200 is formed to correspond to the first mold 100, at least a portion is in close contact with the first mold 100, and a third cavity 1310 is formed to form the first cavity ( 110) and a sealed injection space can be formed.

The first mold 100 may be provided as an upper mold, and the third mold 1200 may be provided as a lower mold to constitute an injection mold.

The third mold 1200 has a third insulating layer 1300 thereon.

The third insulating layer 1300 is the same member as the first insulating layer 200 .

The third mold 1200 is not provided with a heating layer, but is disposed to face the first mold 100 and is in close contact with the first mold 100 to form an injection space 1220 to form an injection space 1220 resin can be injection molded.

When the third mold 1200 does not include a heating layer, injection molding may be performed according to heating of the first heating layer 300 provided in the first mold 100 .

In one embodiment, the third mold 1200 is provided as an upper mold, and the second mold 600 is provided as a lower mold, and it is also possible to configure an injection mold.

The operation sequence of the injection mold according to the embodiment of the present invention will be described as follows.

First, the first mold 100 may be provided as an upper mold, and the second mold 600 may be provided as a lower mold to constitute an injection mold for injection molding. At this time, the first mold 100 may be provided to be movable in the vertical direction, or the second mold 600 may be provided to be movable in the vertical direction, for example, the first mold 100 may be It moves toward the second mold 600 and comes into close contact with the second mold 600 .

When the first mold 100 and the second mold 600 come into close contact, an injection space 1100 is formed therein, and when the first heating layer 300 and the second heating layer 800 are heated, the The molten material or the molten resin flows into the injection space 1100 through the injection hole 610 of the second mold 600, and the molten material or resin is pressurized to produce a molded product along the shape of the injection space 1100. injection molded.

At this time, even if the first heating layer 300 and the second heating layer 800 are heated very rapidly, the heating layer is not heated locally, and since the entire surface is uniformly heated, it is possible to very effectively prevent defects in the molded product. have.

After the injection molding is completed, the first mold 100 is moved, and the injection molded product is separated from the second mold 600 and recovered.

Therefore, the injection mold provided with the heating layer according to the present invention directly forms the heating layer on the core of the mold, and as compared to the indirect heating method using steam or electricity, the temperature increase rate is high and uniform heating is possible, greatly increasing the injection molding efficiency. can increase

Another aspect of the present invention relates to a method for manufacturing an injection mold having a heating layer.

8 is a process flowchart of a method for manufacturing an injection mold having a heating layer according to another aspect of the present invention.

Referring to FIG. 8 , the method for manufacturing an injection mold having a heating layer includes the steps of: (a) forming a cavity in a core portion of the mold; (b) forming an insulating layer on the mold; (c) forming a heating layer comprising titanium dioxide on the insulating layer; (d) forming a plurality of electrodes in contact with the heating layer; and (e) forming a protective layer on the heating layer and the electrode.

First, a cavity is formed in the core portion of the mold (S100).

The molds are disposed opposite to each other to be in close contact with each other, and may be a first mold or a second mold constituting the injection mold.

The mold is preferably made of the same material, and specifically, it may be made of aluminum alloy steel or tool steel containing carbon, and it is also possible to process an existing injection mold to form a cavity and utilize it. For example, it can be manufactured by etching the core of the existing injection mold within 2 mm to form a cavity.

An insulating layer is formed on the upper portion of the mold ( 200 ).

The insulating layers formed in the first mold and the second mold may be a first insulating layer and a second insulating layer, respectively, and are formed by the same process, and metal oxide powder particles having an average particle size of 15 to 35 μm based on D ₅₀ are used. It is preferable to select and form by thermal spray coating.

Before forming the first and second insulating layers, it is preferable to wash the cavity with an organic solvent to remove impurities and oil films in advance, and after forming the first and second insulating layers, silicon-based or epoxy-based compounds It is very desirable to increase the insulation strength by sealing using the sieve and drying at 100° C. or less for 24 hours or more.

A heating layer including titanium dioxide is formed on the insulating layer (S300).

First and second heating layers may be formed on the first and second insulating layers, respectively, and the first and second heating layers may include titanium dioxide.

Specifically, it may be formed by plasma spray coating of titanium dioxide powder, and it is preferable to select a spherical powder having a particle size of 0.01 μm to 100 μm for titanium dioxide and plasma spray coating.

For example, the average particle size may be preferably 5 μm to 45 μm based on D ₅₀ , and more preferably 15 μm to 25 μm based on D ₅₀ .

Titanium dioxide having a particle size within the above range can be plasma-sprayed as a spherical powder, its dispersibility is increased, and a very uniform heating layer can be formed by imparting fluidity of particles in the plasma-sprayed coating process, and upper heating It is possible to increase the stability of the layer and the lower heating layer.

Titanium dioxide having a particle size within the above range forms a titanium dioxide substrate by plasma in the thermal spray coating process, and the transition metal and oxides of the transition metal added together are mixed and changed to coexist, so that the first insulating layer and the second 2 The first heating layer and the second heating layer may be firmly deposited on the insulating layer.

In one embodiment, the first and second insulating layers may be formed by adding a transition metal to a titanium dioxide substrate and thermal spray coating.

Specifically, it is preferable that the transition metal can be thermally coated with a powder having a particle size of 0.01 μm to 100 μm.

The particle size of the transition metal is determined according to the particle size of the titanium dioxide, and when a transition metal having a particle size within the above range is used, when the heating element mixture is physically mixed, localization of the transition metal particles is prevented and heat is generated. It can be made so that the layer exhibits even exothermic characteristics.

In one embodiment, when titanium dioxide powder having an average particle size of 25 μm based on D ₅₀ is used, it is preferable to select particles of 10 μm or less based on D ₅₀ for transition metal particles.

The transition metal is preferably at least one of nickel (Ni), cobalt (Co), zinc (Zn), chromium (Cr), tungsten (W), and molybdenum (Mo).

The first heating layer and the second heating layer are formed by plasma thermal spray coating by mixing titanium dioxide and transition metal powder, so that the transition metal and transition metal oxide are dispersed to increase deposition stability, and in particular, stability when heated at high temperature is increased.

In one embodiment. When the first heating layer and the second heating layer are formed by plasma spray coating, a transition metal and a transition metal oxide may be dispersed in a titanium dioxide substrate, and the transition metal and the transition metal oxide may be dispersed in 100 parts by weight of titanium dioxide. It may be included in an amount of 30 parts by weight or less.

When the transition metal and the transition metal oxide are dispersed and included within the above range, the first heating layer and the second heating layer may exhibit a very uniform heating effect.

A plurality of electrodes are formed on the heating layer (S400).

The plurality of electrodes may be formed to be in electrical communication with both ends of the first heating layer and the second heating layer to form an upper electrode and a lower electrode.

A protective layer may be formed on the heating layer and the electrode (S500).

Specifically, a first passivation layer and a second passivation layer may be formed on the first heat generating layer and the second heat generating layer, respectively.

The first and second protective layers are the same members as the first and second insulating layers, and are preferably formed by the same process.

In one embodiment, the first insulating layer and the second insulating layer, and the first heating layer and the second heating layer may be formed by plasma spray coating.

The first insulating layer, the second insulating layer, the first heating layer, and the second heating layer may all be formed by plasma spray coating, so that the heating layer directly in the first cavity and the second cavity of the first mold and the second mold Formation is possible, and an injection mold equipped with a heating layer can be manufactured very effectively.

In one embodiment, the first protective layer, the second protective layer, and the plurality of electrodes may also be formed by plasma spray coating, in this case, the insulating layer, the heating layer, the electrode and the first mold and the second mold are sequentially formed. By forming the protective layer, injection mold manufacturing efficiency can be greatly increased.

Therefore, in the method for manufacturing an injection mold with a heating layer according to another aspect of the present invention, a first mold and a second mold are formed, respectively, a first cavity and a second cavity are formed in the core portion, respectively, and a plasma spray coating method is used. In this way, the injection mold manufacturing efficiency is very high by laminating the insulating layer and the heating layer, and there is no restriction on the mold shape. It is possible to manufacture injection molds that can be significantly reduced.

Hereinafter, the present invention will be described in more detail through examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example 1. Preparation of injection mold

(1) Preparation of injection mold

Using carbon steel with dimensions of 490mm × 300mm × 70mm (W × L × T) as the first mold and the second mold, each having a cavity with a depth of 1.5 mm in the core was prepared, and mixed with ethanol and water as an organic solvent. The solution was selected and the surface of the mold was washed to remove impurities and oil film. After washing with an organic solvent, sand blasting was performed to remove impurities, and drying was performed at 100° C. for 5 hours to complete the pretreatment.

(2) Formation of an insulating layer

After pretreatment, the inert gas Ar gas is supplied while the DC arc is discharged to the nozzles of the cathode (W) and the anode (Cu) of aluminum oxide (Al ₂ O ₃ ) powder having a particle size of 15 to 35 μm based on D ₅₀ , and Plasma was formed by ionization, and powder was added at an amount of 25 g/min to form a first insulating layer and a second insulating layer with a size of 490 mm × 200 mm (W × L) in the core part except for the tap part of the first mold. formed. The thickness of the first insulating layer and the second insulating layer was adjusted to 300 μm.

After forming the insulating layer, it was dip-coated with a silicone-based compound, dried at 100° C. or lower for 24 hours, and sealed.

After surface treatment, the thickness of the first insulating layer was adjusted to 350 μm.

(3) Formation of a heating layer

Using 1,000 g of titanium dioxide (TiO ₂ ) powder having a particle size of D ₅₀ of 15 to 35 μm, plasma thermal spray coating was performed on the upper surface in the same manner to form a heating layer of the heating layer.

The areas of the first heating layer and the second heating layer were smaller than the areas of the first and second insulating layers, so that the total thermal sprayed area was 240 mm × 175 mm (W × L), and the thickness was 100 μm. was adjusted as much as possible.

(4) electrode formation

On both ends of the first and second heating layers, tungsten (W) powder having a particle size of 15 to 45 μm based on D ₅₀ was plasma spray coated to form electrodes with an area of 63 mm × 50 mm (W × L), respectively. At this time, the thickness of the electrode was adjusted to 50㎛.

(5) formation of a protective layer

The first protective layer was formed on the first heating layer in the same manner as the first insulating layer and the second insulating layer, and the second protective layer was formed on the second heating layer.

At this time, the thickness of the first protective layer and the second protective layer was adjusted to be 100 μm.

Finally, the first mold on which the first protective layer was formed and the second mold on which the second protective layer was formed were recovered to complete an injection molding mold using the first mold as the upper mold and the second mold as the lower mold.

(6) Injection molded product manufacturing

In an injection mold having a heating layer having a first mold and a second mold, the first mold and the second mold are brought into close contact, the mold is rapidly heated by applying electricity, and the molten material is introduced and pressurized to 220 mm × 175 mm × 1 An injection molded article of mm (W × L × T) was prepared.

Example 2.

A second mold was prepared the same as in Example 1, but the first heat generating layer was a mixture of 1,000 g of titanium dioxide (TiO ₂ ) powder having a particle size of D ₅₀ of 15 to 35 μm and 10 g of Ni powder having a particle size of D ₅₀ of 10 μm or less ( Powder Mixer) was used to prepare a mixed powder for 24 hours, and the mixed powder was washed with a stirrer for 1 hour and dried in an oven at 100° C. for 2 hours or more through a filtration filter to prepare a prepared mixed powder.

A heating layer containing transition metals and transition metal oxides was formed by plasma thermal spray coating on the upper surfaces of the first and second insulating layers using the mixed powder in the same manner to form a first heating layer and a second heating layer. The provided first mold and second mold were manufactured, and the injection molding mold was completed by using the first mold as the upper mold and the second mold as the lower mold.

Experimental Example 1. Confirmation of first mold heating effect

A first mold was prepared according to Example 2, but the heating layer was formed by changing the addition amounts of titanium dioxide and nickel, a transition metal, as shown in Table 1 below. After applying a voltage of 100 V as a rated voltage for 10 seconds, the heating temperature was Confirmed.

Titanium dioxide: transition metal (content ratio, parts by weight) Applied voltage (V) Exothermic temperature (℃) Preparation Example 1 100:1 100 120 Preparation 2 100: 5 100 100 Preparation 3 100: 10 100 80 Comparative Example 1 100:11 100 75 Comparative Example 2 100 : 0 100 70

It was confirmed that the exothermic temperature was changed according to the content ratio of titanium dioxide and nickel, and it was confirmed that the calorific value increased when nickel was added within a certain range compared to the case where the exothermic layer was formed with titanium dioxide alone.

Experimental Example 2. First mold heating performance

The exothermic performance of the first mold manufactured according to Example 1 was confirmed.

After connecting an electric cable to both ends of the electrode of the first mold, AC power was applied for 5 seconds or 12 seconds to check the heating performance.

The temperature of the first heating layer was measured using an infrared camera and a thermal imaging camera, and was measured at a distance of about 1 m from the surface of the heating layer.

9 is a photograph showing a temperature measurement of a thermal imaging camera for evaluating the heating performance of an injection mold provided with a heating layer according to an embodiment of the present invention, and FIG. 10 is a heating layer according to an embodiment of the present invention. It is a graph showing the amount of heat generated when a 220V voltage is applied to the provided injection mold for 12 seconds, and FIG. 11 is a graph showing the amount of heat generated when a 380V voltage is applied to the injection mold having a heating layer according to an embodiment of the present invention for 5 seconds. It is a graph.

Referring to FIGS. 9 to 11 , it was confirmed that a cable was connected to the electrode formed in the first mold, and electricity was applied to be heated by the heating layer itself to sufficiently generate heat.

In particular, it was confirmed that when a voltage of 220V is applied to the upper surface on which the heating layer is formed, it can reach 120°C for 12 seconds. In addition, when no voltage was applied, the temperature rapidly dropped to 40° C. after 5 seconds, confirming that rapid heat generation and cooling were possible.

When heating a mold of the same size with an electric heater, it is difficult to heat over 120℃ in a short time because the temperature of the entire mold as well as the top of the mold rises. It was confirmed that the injection mold provided with the heating layer according to the present invention can rapidly heat and cool, thereby preventing power wastage in the synthetic resin injection process and dramatically increasing the injection efficiency.

On the other hand, when the industrial 380V voltage was applied, it was confirmed that it could rise to 200℃ or more in 1 second and reach 320℃ in 5 seconds. When no voltage is applied, the temperature rapidly rises to 60℃ after 5 seconds. It was confirmed that injection molding of a synthetic resin having a high melting point by descending is also possible.

Experimental Example 3. Check the temperature deviation of the heating layer

To see if the heating layer can exhibit a uniform temperature over the entire surface, the temperature was measured at three different points using a thermal imaging camera, and the deviation from the average temperature was checked.

12 is a graph showing three different temperatures for each time when 220V is applied to an injection mold having a heating layer according to an embodiment of the present invention.

heating time
Measurement location (temperature) 2 seconds 5 seconds 7 seconds 12 seconds sp1(℃) 27 81 92 115 sp2(℃) 28 74 82 102 sp3(℃) 27 82 93 119 Average temperature (℃) 27.333 79 89 112 Temperature range 0.47 3.56 4.97 7.26

Table 2 above shows the three measured temperatures, the average temperature, and the temperature deviation.

Referring to Table 2 and FIG. 12, it was confirmed that the heating layer was uniformly heated from the beginning of heating, and the deviation of the temperature measurement value depending on the location of the heating layer was very uniform, less than 10%, whereby local heating such as steam heating It was confirmed that the defect of the molded product by

Experimental Example 4. Injection molded product surface inspection

The injection mold was constituted by using the first mold prepared according to Example 1 as the upper mold, and the third mold not including the heating layer as the lower mold.

A flat injection molded product with dimensions of 220mm × 175mm × 1 mm (W × L × T) by heating the injection mold by applying a voltage of 380V, and introducing resin and reinforcing material (polycarbonate: 20wt% glass fiber) into the injection space. was prepared.

13 is an enlarged photograph of the surface of the molded article after injection molding according to the exothermic temperature in the injection mold according to one embodiment of the present invention.

Referring to FIG. 13, (a) shows that when the heating layer is not heated, and when glass fiber is included as a reinforcement in the injection mold, irregular white streaks (Glass fiber Streak) are generated, resulting in poor appearance, (b), In (c), in the case of injection molding by heating the heating layer to 200 °C and 300 °C, respectively, it was confirmed that flow marks or glass fiber wires due to the addition of reinforcing material did not appear, preventing deterioration of the quality of the molded product.

14 is a photograph of measuring the thickness of an injection molded article injected from an injection mold according to an embodiment of the present invention.

Referring to FIG. 14 , in (a), 1 mm coating glass (reference) is shown, and in (b), injection-molded products having the same thickness of 1 mm are compared with each other, and coating using an injection mold having a heating layer Glass thickness is very ?湛? It was confirmed that a thin-film injection molded article could be manufactured in a large area.

Therefore, the injection mold with a heating layer according to the present invention can directly heat the molten synthetic resin to improve the quality of the injection molded product, and since there is no restriction on the shape of the mold, various injection spaces are formed to form the injection molded product at low cost In particular, it is possible to effectively manufacture injection-molded products such as thin and large-area TV panel cases.

Up to now, the present invention has been mainly examined in the examples. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

100: first mold 110: first cavity ratio
200: first insulating layer 300: first heating layer
400: electrode 500: first protective layer
600: second mold 610: injection hole
620: second cavity 700: second insulating layer
800: second heating layer 900: electrode
1000: second protective layer 1100: injection space
1200: third mold 1300: third insulating layer
1210: injection hole 1220: injection space

Claims (12)

a first mold having a first cavity formed in the core portion;
a first insulating layer provided on the first mold;
a first heating layer provided on the first insulating layer;
a plurality of electrodes having one end connected to the first heating layer; and
Includes; a first protective layer provided to cover the first heating layer and the electrode;
The first heating layer includes titanium dioxide,
It is formed by plasma thermal spray coating and the transition metal and transition metal oxide are dispersed in a titanium dioxide substrate, and the transition metal and transition metal oxide are included in 100 parts by weight of titanium dioxide in an amount of 30 parts by weight or less,
Injection mold with heating layer.
The method of claim 1 , further comprising: a second mold formed to correspond to the first mold, at least a portion of which is in close contact with the first mold, and a second cavity is formed to form an injection space closed with the first cavity;
a second insulating layer provided on the second mold;
a second heating layer provided on the second insulating layer;
a plurality of electrodes connected to the second heating layer; and
Further comprising; a second protective layer provided to cover the second heating layer and the electrode,
The second heating layer includes titanium dioxide,
It is formed by plasma thermal spraying coating and the transition metal and transition metal oxide are dispersed in a titanium dioxide substrate, and the transition metal and transition metal oxide are included in 100 parts by weight of titanium dioxide in an amount of 30 parts by weight or less, a heating layer is provided injection mold.
The method of claim 1, further comprising: a third mold formed to correspond to the first mold, at least a portion of which is in close contact with the first mold, and a third cavity is formed to form an injection space closed with the first cavity; and
The injection mold with a heating layer further comprising; a third insulating layer provided on the third mold.
delete The heating layer of claim 1, wherein the transition metal is at least one of nickel (Ni), cobalt (Co), zinc (Zn), chromium (Cr), tungsten (W), and molybdenum (Mo). Equipped injection mold.
The injection mold with a heating layer according to claim 1 or 2, wherein the first heating layer and the second heating layer have an average thickness of 10 to 500 μm.
The injection with a heating layer according to claim 1 or 2, wherein the first heating layer and the second heating layer have a deviation of less than 10% of the temperature measurement values at at least three different points when a voltage of 220V is applied. mold.
According to any one of claims 1 to 3, wherein the first insulating layer, the second insulating layer and the third insulating layer is aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), boron nitride (BN) ), YAG (Y ₃ Al ₅ O ₁₂ ), and magnesium oxide (MgO) comprising at least one of, the injection mold with a heating layer.
The heating layer according to any one of claims 1 to 3, wherein the first insulating layer, the second insulating layer and the third insulating layer exhibit a resistance value of 900 to 1,000 MΩ when a voltage of 1,000 V is applied. Equipped injection mold.
The injection mold with a heating layer according to claim 2 or 3, wherein the depth of the injection space is 1 mm or less.
(a) forming a cavity in the core portion of the mold;
(b) forming an insulating layer on the mold;
(c) forming a heating layer comprising titanium dioxide on the insulating layer;
(d) forming a plurality of electrodes in contact with the heating layer; and
(e) forming a protective layer on the heating layer and the electrode, including;
The heating layer is one in which a transition metal and a transition metal oxide are dispersed in a titanium dioxide base, and the transition metal and the transition metal oxide are included in 100 parts by weight of the titanium dioxide in an amount of 30 parts by weight or less, and is formed by plasma spray coating ,
A method of manufacturing an injection mold equipped with a heating layer. delete

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