KR100542650B1 - a mold for Light Guide Panel forming - Google Patents

Abstract

The present invention relates to a mold for forming a light guide plate that can reduce deformation due to non-uniform cooling occurring during precision injection molding of a non-printed light guide plate and a decrease in brightness and uniformity. By changing the pitch of, but by decreasing the heat transfer rate by the tube group from the inlet side to the outlet side so as to be uniform throughout the mold, the light guide plate molding die that can reduce the deformation of the light guide plate according to the difference in the heat transfer rate of the mold.

Unprinted LGP, Channel, Heat Transfer Rate, Finite Element Analysis

Description

Mold for Light Guide Panel Forming {a mold for Light Guide Panel forming}             

1 is a plan view showing a mold for forming a light guide plate according to an embodiment of the present invention.

2 is a cross-sectional view of A-A of FIG.

Figure 3 is a perspective view showing a mold for forming a light guide plate according to an embodiment of the present invention.

Figure 4 is a view showing the results of finite element analysis using the temperature distribution of the fixed side mold of the light guide plate molding die according to an embodiment of the present invention as a two-dimensional model.

5 is a view showing the results of finite element analysis using the heat transfer rate of the fixed side mold of the light guide plate molding die according to an embodiment of the present invention as a two-dimensional model.

6 is a view showing the results of finite element analysis using the fixed side mold of the light guide plate molding die according to an embodiment of the present invention as a three-dimensional model.

7 is a view showing the results of finite element analysis using a temperature distribution of a fixed side mold of a conventional light guide plate molding die as a two-dimensional model.

8 is a view showing the results of finite element analysis using the heat transfer rate of the fixed side mold of the conventional light guide plate molding die as a two-dimensional model

9 is a view showing the results of finite element analysis using a fixed side mold of a conventional mold for forming a light guide plate as a three-dimensional model.

<Explanation of symbols for the main parts of the drawings>

2: light guide plate 10: mold

12: fixed side mold 14: movable side mold

16: gate 20: official group

22: pipeline 24: pipeline entrance

26: pipeline exit 28: pitch

The present invention relates to a metal mold for forming a light guide plate, and more particularly, a tube group through which preheating and a coolant pass, so as to reduce deformation due to non-uniform cooling occurring during precision injection molding of the light guide plate and a decrease in brightness and uniformity. The present invention relates to a mold for forming a light guide plate which can reduce the deformation of the light guide plate due to a difference in heat transfer rate of the mold by changing the pitch of the mold and decreasing the heat transfer rate by the pipe from the inlet side to the outlet side so as to be uniform throughout the mold.

In line with the recent high-speed information age, the display industry is showing rapid growth, and this trend is expected to continue for some time to come.

Most of the information, including moving images, can only be transmitted through the human eye, and thus, display products have to be developed to satisfy the human vision.

The display device is the result of expressing color close to nature or precision close to nature.

On the other hand, the light guide plate used in the display device as described above is a dimming device that evenly transmits the light to the entire TFT-LCD panel, and in the present case necessarily involves a printing process for forming a dot to direct the light to the front.

However, such a printing process has a long history and stable, but there is a problem that the process is complicated and causes many defects in the printing process.

For this reason, an unprinted light guide plate manufacturing technology has been developed and used so that the light guide plate itself has a light scattering function without a printing process.

However, the above-mentioned nonprinting LGP manufacturing technique is a precision injection molding technique, and it is difficult to manufacture a mold having a temperature control method and a uniform temperature distribution, and is formed when the temperature control method and temperature distribution of the mold are uneven. Molded products have a problem that the appearance of the molded article, the physical properties of the molding material, optical performance, etc. are significantly reduced.

In particular, if the shrinkage is uneven due to the non-uniformity of the cooling rate during the cooling of the mold, the deformation of the molded article is increased, which causes a problem of reducing the brightness and uniformity of the molded article.

An object of the present invention is to solve the above problems, to provide a mold for forming a light guide plate that can reduce the deformation of the light guide plate caused by the difference in the heat transfer rate of the mold by uniformizing the heat transfer rate of the entire mold. have.

In the molding apparatus for forming a light guide plate of the present invention for achieving the above object, in the molding apparatus for molding the light guide plate, the preheating agent and the coolant are circulated in the mold for forming the light guide plate, that is, the fixed side mold and the movable side mold. Each of them is formed, characterized in that the pitch of the tube group is formed differently to prevent deformation of the light guide plate by reducing the difference in heat transfer rate in the entire volume of the fixed side mold and the movable side mold.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 illustrate a mold for forming a light guide plate according to an embodiment of the present invention, in which a light guide plate forming apparatus (not shown) for forming the light guide plate 2 is formed using a mold 10. It is fixed to an injection machine (not shown).

In addition, the mold 10 is composed of a fixed side mold 12 and a movable side mold 14, and melted through a nozzle contact portion (not shown) in a cavity (not shown) formed in the movable side mold 12. The resin is injected into the gate 16 of the mold to form the light guide plate 2, and the movable side mold 14 is retracted to extract the light guide plate 2 formed in the cavity.

On the other hand, the fixed mold 12 and the movable mold 14 is a plate having a predetermined thickness, a plurality of pipe lines 22 forming the pipe group 20 to preheat and cool the mold 10 therein. Is formed, the pipe line 22 is spaced apart on the same surface formed in the pipe inlet 24 and the pipe inlet formed on one side of the mold 10, the pipe outlet (26) in communication with the pipe inlet (24) is Is formed.

At this time, the light guide plate 2 injected by the mold 10 is formed such that the pitch 28 of the conduit 22 is narrower from the inlet side to the outlet side in order to prevent deformation due to a difference in heat transfer rate.

In addition, the pitch of the above tube banks is made of a ratio of 1: 0.83: 0.66: 0.4: 0.33, which is lost as the preheating agent and the coolant introduced into the pipe line 22 flow from the inlet side to the outlet side. The amount of heat discarded and frictional loss of heat inside the pipe can be compensated for in the entire volume of the mold, which is embodied in the following examples.

In addition, through the adjustment of the pitch 28 of the tube group 20 formed as described above, it is possible to reduce the deformation caused by non-uniform cooling generated during the precision injection molding of the light guide plate 2 and the deterioration of brightness and uniformity due to this.

On the other hand, the light guide panel (Light Guide Panel) refers to a thin plate that transmits light, and serves to see the shape represented by the LCD by subsidizing the LCD that does not emit light by itself, the laptop, PDA, mobile phone we use It is a core part that is used a lot in

In addition, the transparent resin constituting the light guide plate may be one that can satisfy the physical properties required as the light guide plate. Thermoplastic resins capable of melt molding such as polymers, polypropylene, polyethylene, high-density polyethylene, copolymers of acrylonitrile, butadiene and styrene, ABS resins, polysulfone resins, and thermoplastic polyester resins.

In addition, methacryl resin is a polymer mainly composed of methyl methacrylate, and in addition to methyl methacrylate homopolymer, methyl methacrylate and a small amount of other monomers, such as up to about 10% by weight, such as methyl acrylate or ethyl acryl. It may be a copolymer of alkyl acrylates such as rate.

Moreover, these transparent resins may contain a mold release agent, a ultraviolet absorber, a pigment, a polymerization inhibitor, a chain transfer agent, antioxidant, a flame retardant, etc. as needed.

On the other hand, since the heat retention and cooling of the resin filled in the cavity are performed through the cavity surface formed in the mold, the heat exchange of the resin molded product depends on the heat transfer rate of the cavity surface.

That is, as the material of the mold cavity surface, it is preferable to use a metal having a higher thermal conductivity than the metal constituting the mold (usually steel), such as steel or an alloy thereof.

Hereinafter, the technical spirit according to the present invention will be described in more detail through Comparative Examples 1 and 2 and Examples 1 and 2.

The technical idea according to the present invention is to adjust the pitch 28 of the conduit 22 formed in the mold 10 to lose heat due to the amount of heat lost as the heat transfer fluid flows from the inlet side to the outlet side, and loss due to frictional loss in the conduit. It is to provide a manufactured mold 10 to be able to compensate the calories.

Thus, Examples 1 and 2 exemplified in the present invention consist of a mold 10 fabricated at a ratio of the pitch 28 of the above-mentioned pipeline 22.

In addition, the mold 10 used in the Comparative Examples and Examples is limited to the mold for producing the 15 "inch light guide plate 2, and the preheating conditions and cooling conditions of the mold 10 are the same as the Comparative Examples and Examples, In Comparative Examples 1 and 2, the tube groups of the molds are formed at equal intervals according to the conventional art. In Examples 1 and 2, the pitch 28 of the tube groups 20 formed on the molds 10 according to the present invention is entered. The mold 10 formed small from the side to the outlet side was used.

In addition, finite element analysis (FEA) used for the test of a comparative example and an Example is an engineering analysis using the numerical analysis method (theory) called a finite element method (FEM).

In other words, numerical analysis of various engineering problems is carried out on a computer using software (FEM program) developed based on the theoretical system of finite element method.

Comparative Example 1

In this Comparative Example 1, the pitch (1: 1: 1: 1: 1: 1) of the tube group formed in the mold is a fixed side mold having equal intervals, and the pitch (1: 0.83: 0.66: 0.4) of the tube group formed in the mold according to the present invention. : 0.33) is compared with the fixed side mold formed small from the inlet side to the outlet side.

On the other hand, the test of the mold according to Comparative Example 1 preheats the mold to 110 ℃ ~ 130 ℃ which is above the glass transition temperature of the resin material to achieve a low molding deformation of the light guide plate to be injected by introducing the hot water at the inlet of the pipe. .

The results of finite element analysis using the conditions of the fixed side mold preheated as described above as a two-dimensional model are shown in the accompanying drawings.

FIG. 7 shows the temperature distribution of the fixed side molds forming the equally spaced pipe groups, and FIG. 8 shows the heat transfer rate of the metal molds forming the equally spaced pipe groups.

Comparative Example 2

In this Comparative Example 2, the pitch (1: 1: 1: 1: 1: 1) of the tube group is a fixed side mold formed at equal intervals, and according to the present invention, the pitch (1: 0.83: 0.66: 0.4: 0.33) of the tube group It is compared with the fixed side mold formed small to the exit side at.

On the other hand, the test of the mold according to Comparative Example 2 preheats the mold to 110 ℃ ~ 130 ℃ above the glass transition temperature of the resin material to achieve a low molding deformation of the light guide plate to be injected by introducing the hot water into the inlet of the pipe line .

The resin melted at 270 ° C. in the preheated mold is injected into the formed cavity of the movable side mold.

Thereafter, the mold is cooled using cooling water at 20 ° C. through the inlet of the pipe.

After the mold is cooled, the movable side mold is retracted to extract the light guide plate formed in the cavity.

9 shows the results of the finite element analysis under the same conditions as the actual process using the entire process of injection of the light guide plate injected by the above mold as a three-dimensional mold model.

Example 1

Example 1 according to the present invention is compared with Comparative Example 1 according to the prior art, and Example 1 was tested as follows under the same conditions as the actual process.

The hot water is introduced into the inlet of the mold, and the mold is preheated to 110 ° C. to 130 ° C. above the glass transition temperature of the resin material to achieve low molding deformation of the light guide plate to be injected.

The results of finite element analysis using the conditions of the fixed side mold preheated as described above as a two-dimensional model are shown in the accompanying drawings.

Figure 4 shows the temperature distribution of the mold according to the present invention, Figure 5 shows the heat transfer rate of the mold according to the present invention.

Example 2

Example 2 according to the present invention is compared with Comparative Example 2 according to the prior art, and Example 2 was tested as follows under the same conditions as the actual process.

The hot water is introduced into the inlet of the mold, and the mold is preheated to 110 ° C. to 130 ° C. above the glass transition temperature of the resin material to achieve low molding deformation of the light guide plate to be injected.

The resin melted at 270 ° C. in the preheated mold is injected into the formed cavity of the movable side mold.

Thereafter, the mold is cooled using cooling water at 20 ° C. through the inlet of the pipe.

After the mold is cooled, the movable side mold is retracted to extract the light guide plate formed in the cavity.

6 shows the results of the finite element analysis under the same conditions as the actual process using the entire process of injection of the light guide plate injected by the mold as a three-dimensional mold model.

Comparison of Comparative Example 1 and Example 1

It can be seen that the mold finite element analyzed in Example 1 is gentler than the temperature distribution of the fixed side mold finite element analyzed in Comparative Example 1, Figure 4 of the present invention shown in the accompanying drawings and FIG. It was found by comparison.

In addition, the heat transfer rate in Example 1 can be seen that the distribution of heat transfer rate is more uniform than the heat transfer rate tested in Comparative Example 1 in the entire mold, according to Figure 5 of the present invention shown in the accompanying drawings and the prior art This can be seen from the comparison of 8.

In addition, in the present invention, it can be seen that the heat transfer occurs actively at the outlet side of the mold, the above result is that the heat transfer fluid flows from the inlet side to the outlet side by adjusting the pitch of the tube group formed in the mold of Example 1 This is because the amount of heat lost and the amount of heat lost due to frictional losses in the pipe can be compensated for the entire mold.

Comparison of Comparative Example 2 and Example 2

According to the present invention, Example 2 in which the entire process of injection of the light guide plate injected by the mold under the same conditions as the actual process is compared with Comparative Example 2 in which the entire process of injection of the light guide plate injected by the conventional mold is analyzed. It shows the deformation of the molded article by non-uniform cooling.

In addition, when the mold according to the present invention is applied, the deformation of the molded article by the non-uniform cooling was shown, and the mold according to the present invention was confirmed to reduce the deformation due to non-uniform preheating and cooling.

That is, as shown in the accompanying drawings, the deformation amount was also large in FIG. 9 according to the prior art, and it can be seen that the distribution of the deformation amount caused by cooling was asymmetric. This asymmetric deformation weighted the deformation of the molded article taken out. Let's go.

However, in FIG. 6 according to the present invention, the amount of deformation is minute and the distribution of the amount of deformation due to cooling is symmetrical to reduce the deformation due to cooling unevenness.

In conclusion, the decrease in deformation due to non-uniform preheating and cooling increases the brightness and uniformity. For this purpose, the heat loss is lost as the heat transfer fluid flows from the inlet side to the outlet side by adjusting the pitch of the tube group formed in the mold. The amount of heat lost due to frictional losses in the mold can be compensated for the entire mold, enabling uniform preheating and cooling.

As described above, the light guide plate molding die of the present invention changes the pitch of the tube group through which the preheating agent and the coolant pass, while decreasing the heat transfer rate by the tube group from the inlet side to the outlet side so as to be uniform in the entire volume of the mold. In addition, it is possible to reduce the deterioration of deformation, brightness and uniformity caused by non-uniform cooling that occurs during precision injection molding of the light guide plate. The symmetry of the strain distribution is also maintained, thereby increasing the brightness and uniformity of the light guide plate.

Claims (3)

In the molding apparatus for molding the light guide plate 2, The tube group 20 is formed in each of the mold 10 for forming the light guide plate 2, that is, the inside of the fixed side mold 12 and the movable side mold 14 to circulate the preheating agent and the coolant, respectively. 12) and the pitch 28 of the tube group 20 is formed differently to prevent the deformation of the light guide plate 2 due to non-uniform preheating and cooling by reducing the difference in heat transfer rate in the entire volume of the movable mold 14. Mold for light guide plate molding. The method of claim 1, The pitch 28 is a light guide plate molding die, characterized in that formed narrower from the inlet side to the outlet side of the tube group (20). In the molding apparatus for molding the light guide plate 2, The tube group 20 is formed in the mold 10 for forming the light guide plate 2, that is, the fixed side mold 12 and the movable side mold 14 to circulate the preheating agent and the coolant, and the fixed side mold 12 ) And the pitch 28 of the tube group 20 becomes narrower from the inlet side to the outlet side so as to reduce the difference in heat transfer rate in the entire volume of the mold 14 and the movable side mold 14 to prevent deformation of the light guide plate 2 due to uneven preheating and cooling. Mold for forming a light guide plate, characterized in that formed.

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