KR200340414Y1 - Gate structure of mold forming uniform injection molding products - Google Patents

Abstract

The disclosed subject matter relates to a mold gate structure capable of uniform molding. More specifically, as a technique of improving a mold gate for uniform molding of an injection molded product during mold injection, the focus is on manufacturing a high value-added injection molded product by minimizing deformation of the molded product by uniform molding of the injection molded product. The cross-sectional shape of the mold gate according to the present invention is formed in a shape in which the height of the center portion is lower than the height of both side walls, and the wall surface is subjected to surface treatment using a micro sandblast to increase the flow velocity of the side surface rather than the flow velocity of the center portion. Minimized shape flow marks. The mold gate structure capable of uniform molding according to the present invention provides an effect of controlling the flow rate in the mold gate through a micro sandblasting process and a resistance structure formed so that the height of the center portion is lower than the height of both sides. Therefore, the resin flow in the LGP is made uniform, and the defect rate caused by the flow mark is reduced, and the uniform resin flow facilitates the dot pattern design. In addition, the development cost is reduced due to the ease and speed of dot design, and the production yield is increased due to the reduction of defective rate.

Description

Gate structure of mold forming uniform injection molding products

The present invention relates to a mold gate structure capable of uniform molding. More specifically, as a technique of improving a mold gate for uniform molding of an injection molded product during injection molding, the focus is on manufacturing a high value-added injection molded product by minimizing deformation of the molded product by uniform molding of the injection molded product.

In general, a mold is used for molding of castings or plastics, and inserts a thin metal plate or plastic plate between the upper and lower molds and compresses it into a predetermined shape to inject the finished molded product. .

The injection molding method of thermoplastic resin is first made by adding pigments, stabilizers, plasticizers, fillers, etc. to plastics, and making a cylindrical or square chip of several millimeters, that is, compound into hopper. Put it. There is a heating chamber just in front of the inlet, where it is heated by heat transfer, high pressure steam or the like. Next, styrene resin or polyvinyl chloride is heated to about 170 ° C. and polypropylene to about 200 ° C. according to the material to make the plastic molten. This is injected into the mold through the inlet through a piston. As it flows into the corners of the mold, the piston returns to the right and the mold splits in two, pulling the hard plastic out of the mold.

As a conventional mold gate, FIGS. 1A and 1B show the shape of a conventional light guide plate product model and gate portion. The conventional mold gate portion is composed of the LGP body 2 of FIG. 1A and the gate portion 1 of FIGS. 1-2. In order to facilitate the flow of the resin during injection molding, the gate portion 1 is being improved. Typically, the radius of curvature R where the gate and the product meet is increased, and the gate width w is wide. It has been transformed into a form.

2 illustrates an existing light guide plate mold internal structure. The mold 3 is separated into a fixed portion 4 and a movable portion 5, and the liquid resin coming from the sprue 6 of the injection molding machine passes through the bushing 7 of the mold 3 to pass through the gate portion 1. It will be filled into the LGP body (2).

3 shows a resin flow in a conventional gate structure. In such a conventional gate structure, there is a problem in that the gate structure in which a high temperature liquid resin flows at a high speed is constant so that the flow rate cannot be adjusted at all in the gate. Since the light flows from the gate portion 1 to the light guide plate product at the same flow rate, when viewed as the light guide plate product, the gate portion 1 serves as a point source of the resin. From this point source to the light guide plate product, the resin is filled in half moon form and proceeds. In the process, the light guide plate product has a half-moon-shaped flow trace 9 that spreads in the center according to the flow rate, and this flow trace causes the formation of optical defects, thereby degrading the characteristics of the product.

4A-4C show the resin flow in a conventional gate structure for the aforementioned problem. As shown in FIG. 4A, the resin in the fluid state flows through the gate portion, and since the flow of the fluid is smaller than the fluid velocity and pressure, all points in the gate are subjected to the same velocity pressure. Therefore, as shown in FIG. 4B, the boundary line 8 between the gate and the product acts as a point source through which resin is discharged. That is, since the structure of the gate cross-section is the same as the rectangle as shown in Fig. 4c, the pressure and velocity of the resin are the same at all sites, so that the resin liquid first reaches a position close to the gate portion, and the position at a distance is As the liquid arrives later, it leaves a half-moon-shaped flow trail that causes product defects.

The mold gate structure capable of uniform molding according to the present invention for solving the problems of the conventional mold gate structure as described above, by forming a conventional rectangular gate cross-sectional structure in a shape having a resistance of resin flow in the center of the cross-section, It is an object of the present invention to provide a mold gate structure capable of uniform molding in which the resin is filled in the most distant and closest place within the same time, so that the resin flow in the light guide plate product is uniform and the defect rate caused by the flow mark is reduced.

1A is a side view and a front view of a conventional light guide plate product model.

1B is an enlarged view of a conventional gate portion.

Figure 2 is an internal structure of a conventional light guide plate mold.

3 is a distribution diagram of resin flow in a conventional gate structure.

4A-4C are illustrations of resin flow in conventional gates.

5A is a structural diagram of a mold gate having a cross-sectional shape of a resistance structure according to a first embodiment of the present invention;

Figure 5b is a structural diagram of a mold gate by a micro sandblast surface treatment according to a second embodiment of the present invention.

6 is an exemplary view of a resin flow in a mold gate according to an embodiment of the present invention.

7A to 7C are cross-sectional views of a gate shape having a resistance structure according to the first embodiment of the present invention.

8 is a resin flow distribution diagram in a mold gate according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1 gate 2 LGP main body

3: mold 4: fixing part

5: movable part 6: sprue

7 bushing 8 borderline

9: half moon mark 10: center

20: side 30: triangular bone

40: elliptical bone

According to the present invention for achieving the object as described above, the mold gate structure capable of uniform molding is a mold gate structure in which a fluid resin flows into the light guide plate through the gate portion, and the cross-sectional shape of the gate has both sides of the height of the center portion. Characterized in that the shape is lower than the height of the side wall.

According to a preferred feature of the present invention, the center portion is formed in a triangular bone shape or an elliptical bone shape is characterized in that the center height of the center portion is the shortest height in the cross section of the gate portion.

The gate portion may be surface-treated using a micro sandblast on the sidewall surface thereof.

In addition, the gate portion is characterized in that the surface treatment using a micro sandblasting while having an inclination to the bottom surface and the ceiling surface in the lateral direction.

The gate portion may be surface-treated using micro sandblasting on its sidewall, bottom and ceiling surfaces.

The mold gate structure capable of uniform molding according to the present invention configured as described above forms an inclination along the center portion of the inner end surface of the mold gate into which the resin is introduced, so that the velocity of the fluid flowing through both sidewalls is faster than the speed of the center portion. Therefore, the rate of filling the resin into the mold is constant, which prevents the deterioration of the product characteristics due to the half-moon flow marks.

FIG. 1A is a side view and a front view of a conventional light guide plate product model, and FIG. 1B is an enlarged view of a conventional gate portion in FIG. 1A. 2 is an internal structural diagram of a conventional light guide plate mold, FIG. 3 is a distribution diagram of resin flow in a conventional gate structure, FIGS. 4A to 4C are illustrations of resin flow in a conventional gate, and FIG. 5A is a first embodiment of the present invention. 5 is a structural diagram of a mold gate having a micro sandblast surface treatment according to a second embodiment of the present invention, and FIG. 6 is an embodiment of the present invention. 7A to 7C are cross-sectional views of a gate shape having a resistance structure according to a first embodiment of the present invention, and FIG. 7 is a mold gate according to an embodiment of the present invention. It is resin flow distribution map in the inside.

Hereinafter, a preferred embodiment of the present invention including the above components will be described in more detail with reference to the accompanying drawings.

5A shows a structure of a mold gate having a cross-sectional shape of a resistance structure according to the first embodiment of the present invention. The present invention solves the drawback of deteriorating product characteristics due to the remaining half moon-shaped flow marks that spread from the center during molding due to the flow rate difference of the resin filling into the mold gate. Therefore, in order to minimize the flow pattern of the half moon shape, the inclination was formed such that the height of the central portion 10 was lower than the height of the side walls 20 on both sides.

Since the resistive structure due to the relatively low height of the center portion 10 increases the flow rate of filling through the side wall 20 rather than the flow rate of the center portion, the resin is filled equally from the gate portion to the end of the mold to form a half moon flow mark. By minimizing

As described above, an embodiment of the mold gate structure capable of uniform molding according to the present invention is configured. The technical scope of the present invention is not necessarily limited to the above-described embodiment, and various modifications and application examples are possible without departing from the technical scope of the present invention.

5B shows a mold gate by micro sandblast surface treatment on the side wall surface according to the second embodiment of the present invention. In the present invention, the resin filling rate in the mold is controlled. In the first embodiment, the resistive structure is formed and the hydrodynamic flow is improved by adjusting the cross-sectional area of the gate part by adjusting the width and height of the central portion 10. In the second embodiment, the micro sandblasting treatment is performed on both side surfaces of the gate to improve the flowability flowing through both side surfaces 20.

6 shows the resin flow in the mold gate according to the first and second embodiments described above. The length of the arrow mark is intended to indicate that the flow velocity of both side surfaces 20 is faster than the flow velocity of the central portion 10. The half moon-shaped flow marks were minimized by improving the flow rate on the side through the cross-sectional resistance structure according to the slope of the center of the first embodiment or the micro sandblasting treatment of the second embodiment. It is also very desirable to improve the resin flowability of both sides by mixing the first and second embodiments to form a resistive structure having a slope of the cross section of the center portion, and micro sandblasting treatment on both sides, the bottom, or the ceiling surface. Do.

7A to 7C show a cross section of a gate shape having a resistance structure according to the first embodiment of the present invention. First, in FIG. 7A, the bottom surface of the mold gate is configured as a triangular bone 30 to form a resistance structure having a sloped surface with the height of the center of the center portion 10 as the shortest. FIG. 7B illustrates a resistance structure in which the bottom surface and the ceiling surface are formed in the elliptical bone 40 type. And, Figure 7c shows a resistance structure consisting of a triangular bone 30 type of the ceiling surface.

FIG. 8 shows the resin flow distribution in a mold gate according to an embodiment of the present invention as opposed to the conventional distribution shown in FIG. 3. In the present invention, since the flow velocity of the side surface is faster than the center portion, the defect rate of the product is remarkably decreased by eliminating the half-moon-shaped flow marks shown in FIG. 3.

As such, when analyzing the resin flow by the mold gate structure according to the present invention, the resin pressure and velocity, that is, the physical vector value, at the starting point of the gate are different from the center and both sides. This causes the resin to be filled in approximately the same time as the furthest from the gate and the closest to the straight line. As a result, the resin flow in the light guide plate becomes constant in the direction parallel to the light guide plate longitudinal direction.

As described above, an embodiment of the mold gate structure capable of uniform molding according to the present invention is configured. The technical scope of the present invention is not necessarily limited to the above-described embodiment, and various modifications and application examples are possible without departing from the technical scope of the present invention.

The mold gate structure capable of uniform molding according to the present invention provides an effect of controlling the flow rate in the mold gate through a micro sandblasting process and a resistance structure formed so that the height of the center is lower than the height of both sides.

Therefore, the resin flow in the LGP is made uniform, and the defect rate caused by the flow mark is reduced, and the uniform resin flow facilitates the dot pattern design. In addition, the development cost is reduced due to the ease and speed of dot design, and the production yield is increased due to the reduction of defective rate.

Claims (5)

A mold gate structure in which a fluid resin flows into a light guide plate through a gate portion, The cross-sectional shape of the gate is a mold gate structure capable of uniform molding, characterized in that the height of the center portion is formed in a shape lower than the height of both side walls. The method of claim 1, The central portion, Formed in a triangular bone shape or elliptical bone shape, the center height of the center portion is a mold gate structure capable of uniform molding, characterized in that the shortest height in the cross section of the gate portion. The method of claim 1, The gate is, The metal mold | die structure which can be uniformly shape | molded by the surface which used the micro sandblast on the side wall surface. The method of claim 1, The gate is, A mold gate structure capable of uniformly forming, characterized in that the surface is processed using a micro sandblasting while having a slope on the bottom surface and the ceiling surface in the lateral direction. The method of claim 1, The gate portion, A mold gate structure capable of uniform molding, wherein the sidewall surface, the bottom surface, and the ceiling surface are surface-treated using micro sandblasting.