JP4035000B2 - Mold equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold apparatus, and more particularly, to a mold apparatus for molding a synthetic resin suitable for a heat cycle method in which a cavity surface is alternately heated and cooled for molding.
[0002]
[Prior art]
In injection molding of thermoplastic resin, if the mold temperature is set high when filling the mold cavity with the molten resin, the fluidity of the resin is good, so that the transfer of the cavity surface is good and the weld line is not noticeable. Therefore, a heat cycle method in which the cavity surface is heated only while the molten resin is filled in the cavity has been put into practical use.
[0003]
The present applicant has previously proposed a synthetic resin molding die apparatus to which a heat cycle molding method is applied as shown in FIG. 4 according to Japanese Patent Application No. 11-375069 (Japanese Patent Laid-Open No. 2001-18229). Yes.
[0004]
This synthetic resin molding die apparatus includes a mother die 21 and a nest 22 incorporated therein. A cavity surface 23 is formed in the nest 22, and in the vicinity of the cavity surface 23, a water pipe 24 into which a heating medium and a cooling medium are alternately introduced is provided. Between the insert 22 and the mother die 21, a heat insulating layer 25 made of a material having a low thermal conductivity such as air held in a recess is provided.
[0005]
When heat cycle molding is performed using the above-described conventional mold apparatus, burrs tend to appear around the molded product. The burr is generated when the resin 22 penetrates between the contact surfaces of the two inserts 22 and solidifies in a so-called parting line where the inserts 22 of the fixed mold and the movable mold come into contact with each other. The burr is generated by the same principle even in a so-called direct engraving type die apparatus that is not nested.
[0006]
Generally, the temperature of the nesting (mold) itself is low in the normal molding method in which the resin is filled while keeping the cavity temperature constant at a low temperature, whether it is a nesting mold apparatus or a direct-engraved mold apparatus. Since the tip portion of the resin flowing in the cavity is cooled and the viscosity is high, the resin that has reached the parting line is less likely to enter between the contact surfaces of both inserts (both molds), and burrs are less likely to occur. However, in the heat cycle molding method described above, the cavity surface temperature is increased during resin filling (for example, the temperature during resin filling is approximately 120 ° C.), and the tip portion of the resin flowing in the cavity is difficult to cool and has a viscosity. Therefore, the resin that has reached the parting line is likely to enter between the contact surfaces of both inserts (both molds). For this reason, burrs are more likely to occur in the heat cycle molding method than in the normal molding method.
[0007]
Usually, in order to prevent the occurrence of burrs in the injection molding method, it is effective to increase the contact pressure of both inserts (both molds) in the parting line, and contact using a molding machine with a large clamping force. The contact pressure is increased by increasing the pressure or by reducing the contact area of both inserts (both molds) in the parting line even with a molding machine having the same clamping force. That is, by forming the cavity peripheral edge corresponding to the outer periphery of the molded product higher than the outer part, only the cavity peripheral edge comes into contact with the nest (mold) opposite to the cavity peripheral part, and the contact area is small. The contact pressure increases, and the possibility that the resin enters between the contact surfaces to generate burrs is reduced.
[0008]
[Problems to be solved by the invention]
As described above, the penetration of the resin between the contact surfaces of both inserts (both molds) in the parting line can be considerably prevented by increasing the contact pressure. However, burrs may occur due to different factors.
[0009]
The first factor will be described taking the telescopic mold apparatus shown in FIG. 5A as an example. 5B, 5C, and 5D are enlarged views showing the A portion, the B portion, and the C portion in FIG. 5A, respectively.
[0010]
In such a mold apparatus, the resin 29 is applied to the corner portions 27c and 27d of the contour portion of the pin 27b for forming the cavity peripheral edge portion 27a and the window portion, which are located on the parting line where both the inserts 26 and 27 abut. Intrusion may solidify and thread-like burrs may occur. That is, as shown in FIGS. 5B and 5C, as described above, the resin 29 whose viscosity has been reduced by the heat cycle method enters the gaps in the corner portions 27c and 27d from the parting line, and this intrusion occurs. Thread burrs may occur due to the solidification of the portion 29a. Further, in the case of a mold apparatus in which a plurality of nested inserts 27 are used as shown in FIG. 5A, the resin 29 is adjacent to the inserts 27 as shown in FIG. There is a risk of entering the gap of the corner portion 27e at the position and solidifying the invading portion 29a to become a thread burr.
[0011]
Next, the second cause of the occurrence of burrs will be described with reference to the nested mold apparatus shown in FIG. FIG. 6B is an enlarged view of a portion A in FIG. In this mold apparatus, the surface of the cavity of the nesting 30 on the fixed side is subjected to embossing.
[0012]
In such a mold apparatus, a defective phenomenon may occur in which the contour of the window portion of the molded product becomes jagged. When the cavity surface 30a of the fixed-side insert 30 is subjected to an embossing process, the embossing process is also performed including the part where the pin 31a of the movable-side insert 31 abuts for convenience of processing. When the embossed surface 30a comes into contact with the smooth pin surface 31b, the two surfaces 30a and 31b do not come into close contact with each other. Therefore, as shown in FIG. 6 (b), the resin 29 enters the gap generated in the portion forming the outline of the window portion of the molded product, and the intruded portion 29b is solidified to become a burr. That is, the contour of the molded window portion becomes jagged.
[0013]
As described above, the telescopic mold apparatus shown in FIGS. 5 and 6 has been described. However, in the direct engraving mold apparatus, burrs may occur due to similar factors.
[0014]
Therefore, an object of the present invention is to prevent the invasion of resin into the corner of the mold, and prevent the resin from invading due to the formation of voids in the part forming the contour of the molded product, thereby preventing the occurrence of burrs. An object of the present invention is to provide a mold apparatus for resin molding.
[0015]
[Means for Solving the Problems]
Feature of the present invention, the mold apparatus heat cycle molding is performed repeatedly up and down the temperature of at least one of the cavity surface of the fixed mold and the movable mold, the fixed mold and the movable Gawakin types with each other The radius of curvature of the corner portion of the cross section perpendicular to the parting line of the abutting portion is 0.01 mm to 0.2 mm, and the surface of the cavity of the fixed mold is subjected to surface roughening. The tip of the pin of the movable mold that comes into contact is softer than the surface of the cavity that has been subjected to surface roughening, and when pressed against the surface of the cavity that has been subjected to surface roughening, the material can be deformed accordingly. there to become a place. In addition, when a metal mold | die consists of a mother mold and a nesting attached to it, the curvature radius of the corner part of a cross section perpendicular | vertical to the parting line of a nesting is 0.01 mm- 0.2 mm . Further, when at least one of the movable mold and the fixed mold is divided into a plurality of the nestings to be mounted on the mother mold, the part of the portion where the nestings are in contact with each other in the same mother mold The radius of curvature of the corner portion of the cross section perpendicular to the contour line is 0.01 mm to 0.2 mm .
[0016]
Thus, when the radius of curvature of the corner portion is 0.2 mm or less, the resin does not enter the corner portion, and the generation of burrs can be prevented.
[0018]
Furthermore, the surface of the cavity of the fixed mold is subjected to surface roughening, and the tip of the pin of the movable mold that contacts the surface is softer than the surface of the cavity subjected to surface roughening. Because it is made of a material that can be deformed when pressed against the roughened cavity surface, the cavity surface on the fixed side and the tip of the pin come into close contact when the mold is clamped, and the resin enters the contour of the pin Voids do not occur. Therefore, it is possible to prevent the generation of jaggedness in the contour portion of the window portion of the molded product. The surface roughening process may be a textured process.
[0019]
In addition, the longitudinal elastic modulus of the tip portion of the pin is 98 × 10 ^{4 to} 1030 × 10 ⁴ N / cm ² , and a die having a cavity surface to be subjected to surface roughening is used when the tip of the pin is clamped. It is preferable that it consists of the steel material which has the hardness which does not deform | transform even if it contact | abuts a part. When the mold is composed of a mother die and a nest attached to the mother die, the nest has a cavity surface that is subjected to surface roughening, and is in contact with the tip of the pin during mold clamping. It is made of a steel material having a hardness that does not deform.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0021]
FIG. 1 shows a mold apparatus of a first reference example for explaining the present invention. FIG. 1A shows the entire mold apparatus of the present reference example , and FIGS. 1B to 1D are enlarged views of the A part, the B part, and the C part in FIG. 1A, respectively. Show.
[0022]
The mold apparatus of the present reference example is a nesting method in which a nesting is mounted on a mold mother mold. One mold (fixed side mold) 1 has a single nesting 2 mounted on a mother mold 3. The other mold (movable side mold) 4 has a plurality of inserts 5 mounted on a mother mold 6. And the water pipe 7 and the heat insulation layer (air layer) 8 similar to the conventional metal mold apparatus are provided.
[0023]
In this mold apparatus, the corners 5c, 5d, 5e of the insert 5 are formed so that the radius of curvature is 0.2 mm or less so that the corners 5c, 5d, 5e are hardly rounded. 1 (b), the corner 5c of the cavity peripheral edge 5a of the insert 5 that is in contact with the insert 2 opposite thereto, and the insert 5 of the insert 5 shown in FIG. The corner portions 5d of the pins 5b for forming the portions are formed so that the respective radii of curvature are 0.2 mm or less. In addition, as shown in FIG. 1D, the corner portion 5e at the position where the divided nests 5 are adjacent to each other is also formed so that the radius of curvature is 0.2 mm or less.
[0024]
According to this configuration, since the corner portions 5c and 5d located in the parting line of the insert 5 are almost not rounded, there is no gap that allows the resin 10 to enter during mold clamping, and burrs are generated in the molded product. Absent. Further, in the plurality of divided nests 5, there is no gap between the corners 5 e of the adjacent nests 5 to allow the resin 10 to enter.
[0025]
Thus, in order to prevent the resin 10 from entering and preventing burrs, the radius of curvature of each of the corner portions 5c to 5e needs to be about 0.2 mm or less. Is preferably 0.01 to 0.2 mm.
[0026]
Next, a mold apparatus according to a second reference example for explaining the present invention will be described with reference to FIGS. FIG. 2 (a) shows the entire mold apparatus of the present reference example in the mold open state before the molding operation, and FIG. 2 (b) shows the pin 12a of the mold insert 12 shown in FIG. 2 (a). The vicinity of the tip portion 12d is shown enlarged. FIG. 3A shows the entire mold apparatus of the present reference example in the mold closed state, and FIG. 3B shows an enlarged view of a portion A in FIG. In addition, about the part similar to a 1st reference example , the same code | symbol is provided and description is abbreviate | omitted.
[0027]
In the mold apparatus of the present reference example , the stationary insert 11 is made of a steel material having a hardness that does not deform even when it comes into contact with a distal end portion 12d (more specifically, a convex portion 12b) of a pin 12a described later during mold clamping. Specifically, for example, the elastic modulus is formed of a steel material having a longitudinal elastic modulus of about 2100 × 10 ⁴ N / cm ² (for example, a normal mold material such as tool steel SKD61), and the cavity surface is subjected to embossing. The embossed surface 11a has a rough surface roughness. The tip 12d of the pin 12a that abuts against the embossed surface 11a during mold clamping (see FIG. 3) of the movable insert 12 is formed of brass (brass) that is softer than the tool steel SKD61. As shown in FIG. 2 (b), the tip 12d of the pin 12a of this reference example is provided with a convex portion 12b and a concave portion 12c, and the width of the convex portion 12b is about 1.2 mm. The depth of the recess 12c (near the center in the radial direction of the pin 12a) surrounded by is about 0.05 mm.
[0028]
In this mold apparatus, when the mold is clamped, the convex portion 12b of the tip 12d of the pin 12a made of a soft material such as brass is pressed against the embossed surface 11a. Then, the convex part 12b is deform | transformed into the shape corresponding to the embossed surface 11a (refer FIG. 3). At this time, the part that protrudes somewhat with the deformation of the convex part 12b is released into the concave part 12c, and the deformed convex part 12b comes into close contact with the embossed surface 11a, and no gap is generated. Therefore, no burr is generated, and the contour of the window formed by the pin 12a is not jagged as in the prior art.
[0029]
Examples of the soft material constituting the tip 12d of the pin 12a include zinc alloy (ZAS), aluminum and its alloy, copper and its alloy, and the longitudinal elastic modulus is 98 × 10 ^{4 to} 1030 × 10. It is preferable to be within the range of ⁴ N / cm ² (approximately 10 × 10 ^{4 to} 105 × 10 ⁴ kgf / cm ² ).
[0030]
Thus, in the present reference example , the tip 12d of the pin 12a is formed of a soft material such as brass, and the tip 12d is provided with the convex portion 12b and the concave portion 12c. However, the shape of the tip 12d of the pin 12a is not particularly limited as long as at least part of the tip 12d abuts against the opposite cavity surface (the embossed surface 11a in the present reference example ).
[0031]
In the mold apparatus of the second reference example described above, the corner portion is formed by forming the nest so that the radius of curvature of each corner portion is 0.2 mm or less, as in the first reference example. It prevents the penetration of the resin 10 into, it is possible to more reliably prevent occurrence of burrs. This configuration, that is, the configuration combining the first reference example and the second reference example is the mold apparatus of the present invention.
[0032]
Each of the two reference examples described above relates to a nesting mold apparatus, but the present invention is also applicable to a so-called direct carving mold apparatus that is not a nesting type.
[0033]
【The invention's effect】
According to the present invention, it is possible to prevent the resin from entering the corner portion of the mold, and it is possible to prevent the occurrence of voids that allow the resin to enter the portion that forms the contour of the molded product. Can be prevented.
[Brief description of the drawings]
FIG. 1 (a) is a schematic cross-sectional view showing the entire mold apparatus of a first reference example of the present invention, FIG. 1 (b) is an enlarged view showing a portion A in FIG. 1 (a), FIG. 1C is an enlarged view showing a portion B in FIG. 1A, and FIG. 1D is an enlarged view showing a portion C in FIG.
FIG. 2 (a) is a schematic cross-sectional view showing the entire mold apparatus of a second reference example of the present invention in a mold open state before molding, and FIG. 2 (b) is FIG. 2 (a). It is an enlarged view which shows the front-end | tip part vicinity of the nesting pin of the metal mold | die apparatus shown in FIG.
FIG. 3 (a) is a schematic cross-sectional view showing the entire mold apparatus according to a second reference example of the present invention in a mold-closed state, and FIG. 3 (b) is A in FIG. 3 (a). It is an enlarged view which shows a part.
FIG. 4 is a schematic cross-sectional view showing a first example of a conventional mold apparatus.
5A is a schematic sectional view showing the whole of a second example of a conventional mold apparatus, FIG. 5B is an enlarged view showing a portion A in FIG. 5A, and FIG. (C) is an enlarged view showing a portion B in FIG. 5 (a), and FIG. 5 (d) is an enlarged view showing a portion C in FIG. 5 (a).
6A is a schematic cross-sectional view showing an entire third example of a conventional mold apparatus, and FIG. 6B is an enlarged view showing a portion A in FIG. 6A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed side metal mold | die 2 Single nest | insert 3,6 Master mold 4 Movable side metal mold | die 5 Divided in multiple 5a Cavity peripheral part 5b Pin 5c, 5d, 5e Corner part 7 Water pipe 8 Heat insulation layer (air layer)
DESCRIPTION OF SYMBOLS 10 Resin 11, 12 Nest 11a Textured surface 12a Pin 12b Convex part 12c Concave part 12d Tip part

Claims (6)

In a mold apparatus in which a heat cycle molding method for repeatedly raising and lowering the temperature of the cavity surface of at least one of a movable mold and a fixed mold is performed,
Wherein the fixed mold and the parts movable Gawakin mold abuts each other, the curvature radius of the corner portion of the cross section perpendicular to the parting line is 0.01 mm to 0.2 m m,
Surface roughening is performed on the cavity surface of the stationary mold, and the tip of the pin of the movable mold that is in contact with the surface is softer than the cavity surface on which the surface roughening is performed, A mold apparatus comprising a material that can be deformed when pressed against the surface of the cavity subjected to the surface roughening process . The said metal mold | die consists of a mother mold and a nest | attachment attached to it, The curvature radius of the corner | angular part of a cross section perpendicular | vertical to the parting line of the said nest | insert is 0.01 mm- 0.2 mm. Mold equipment. Wherein the fixed side mold of at least one the movable metal mold, said nest being mounted on said mold is divided into a plurality,
Wherein the same said mold nest each other abutting portions, the curvature radius of the corner portion of the cross section perpendicular to the parting line is 0.01 mm to 0.2 m m, mold apparatus according to claim 2 . The mold apparatus according to claim 1, wherein the surface roughening process is a textured process. The longitudinal elastic modulus of the tip portion of the pin is 98 × 10 ^{4 to} 1030 × 10 ⁴ N / cm ² , and the fixed side mold having the cavity surface subjected to the surface roughening process is configured to The mold apparatus of any one of Claim 1 to 4 which consists of steel materials which have the hardness which does not deform | transform even if it contact | abuts with the front-end | tip part of a pin. Before SL nested, it has a cavity surface, wherein the surface roughening process is applied, consisting of a steel material having a hardness which is not deformed even in contact with the tip portion of the pin during clamping person, according to claim 2 Mold equipment.

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