JP4260347B2 - Mold for resin molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin mold, and more particularly to a resin mold that can uniformly heat or cool the entire mold in a short time.
[0002]
[Prior art]
In resin molding, in order to improve product quality and productivity, it is required to heat or cool the entire molding die in a short time. As means for enabling this, JP-A-5-38749, Those described in Japanese Utility Model Laid-Open No. 6-9744 or Japanese Patent Laid-Open No. 7-285169 are known.
[0003]
The molding dies described in each of the above prior arts are provided with a porous sintered metal layer in the vicinity of the molding cavity, and a cooling medium or a heating medium is allowed to flow through the porous layer. It is intended to cool or heat.
[0004]
[Problems to be solved by the invention]
However, the provision of the above-described sintered metal layer has a temporary effect, but the flow rate of the medium flowing in the sintered metal layer is the same for the portion near and far from the forming cavity.
[0005]
On the other hand, the medium involved in cooling or heating is a medium that flows in a portion close to the molding cavity, and the medium that flows in a portion away from the molding cavity is not so much involved. That is, in order to prevent uneven cooling and the like, conventionally, it has been necessary to circulate a larger amount of medium than necessary.
[0006]
[Means for Solving the Problems]
The present invention provides a resin molding die that does not cause uneven heating or cooling. For this purpose, the present invention provides a porous sintered body in which a cooling medium or a heating medium is circulated in the vicinity of a molding cavity. A metal layer was provided, and the particle size of the metal particles constituting the sintered metal layer was arranged so as to be large at a portion near the molding cavity and small at a portion far from the molding cavity.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is an exploded perspective view showing a configuration of a resin molding die according to the present invention, FIG. 2 is a diagram showing a configuration of a mold body, (a) is a front view, (b) is a side view, and (c). FIG. 3 is a bottom view, and FIGS. 3A and 3B are isotherms for explaining the operation.
[0008]
As shown in FIG. 1, the resin molding die according to the present invention covers a mold body 1 having a molding cavity 1a for forming a resin molding product on the surface thereof, covers the molding cavity 1a, and makes this a sealed space. It consists of a lid body 2 in which a hole 2a for supplying molten resin is formed in a molding cavity 1a, a cooling medium supply section 3 and a cooling medium discharge section 4.
[0009]
As is clear from FIG. 2 (a), the mold body 1 is formed with a molding cavity 1a for forming a resin molded product on the surface of the mold body 1, and from FIGS. 2 (b) and 2 (c). As is apparent, three linear square grooves 1b are formed in the vicinity of the molding cavity 1a. Between the three grooves, ribs 9 are defined, and in each groove 1b, a sintered metal plate 5 in which metal particles having a large particle size are joined in order from the molding cavity 1a side, and metal particles having a medium particle size. Each of the square grooves 1b is closed with a groove lid 8 in a state in which the sintered metal plate 6 bonded to each other and the sintered metal plate 7 bonded to metal particles having a small particle diameter are stacked.
[0010]
A cooling medium supply unit 3 is liquid-tightly connected to the side surface 1 c of the mold body 1, and a cooling medium discharge unit 4 is liquid-tightly connected to the side surface 1 d facing the side surface 1 c and supplied from the cooling medium supply unit 3. The cooling medium to be passed through the three grooves 1b reaches the cooling medium discharge part 4.
[0011]
In the resin molding die described above, three rectangular grooves 1b are formed in the vicinity of the molding cavity 1a, and in that order, sintered from metal particles having a medium particle size in order from the molding cavity 1a side. Since the sintered metal plate 6 and the sintered metal plate 7 formed by sintering with metal particles having a small particle diameter are laminated and arranged so that the cooling medium flows in the three grooves 1b, the mold body 1 is When cooling, the surface portion of the mold main body 1 in which the molding cavity 1a is formed is uniformly cooled.
[0012]
Of the sintered metal plates 5, 6, and 7 used in the resin molding die, in order to investigate the degree of uneven cooling, the metal particles having the smallest particle size used for the sintered metal plate 7 were formed. Prepare a comparative mold body that fills the entire volume of the three grooves 1b of the mold body 1 with a sintered metal plate, mold the resin under the same conditions as the resin molding mold of the present invention, and cool under the same conditions The surface temperatures of the mold body 1 and the comparative mold body when the medium was passed were observed.
[0013]
The surface temperature was observed by paying attention to a predetermined temperature in the resin molding process and drawing an isotherm of this temperature. As a result, as shown by dots in FIG. 3 (a), the mold body 1 is larger in each of the three isotherms and spreads over the entire surface of the mold 1, and is in close contact with other isotherms. ing. In the comparative mold main body indicated by dots in FIG. 3B, each of the three isotherms is relatively small, is ubiquitous on the surface of the mold 1, and is separated from other isotherms. This means that the mold body 1 has less cooling unevenness than the comparative mold body.
A vertical dotted line drawn in common in FIGS. 3A and 3B represents the position of the groove 1b. Moreover, the arrow represents the flow direction of the cooling medium.
[0014]
The reason why the cooling unevenness is small is that metal particles having a large particle diameter are arranged closer to the molding cavity 1a, so that the gap between the metal particles becomes large, and the cooling medium flows at a large flow rate on the molding cavity 1a side. Can be mentioned.
[0015]
In the above-described embodiment, it has been described that the cooling medium is allowed to flow in the groove 1b on the assumption that the mold is cooled after the resin molding. However, the present invention is not limited to this, and as necessary. The heating medium may be caused to flow through the groove 1b.
[0016]
In the embodiment, the rib 9 defines the groove 1b so that a sufficient mold strength can be obtained even if a perforated plate is used. May be omitted.
[0017]
Moreover, in the Example, the case where the three square grooves 1b were formed in the cavity 1a vicinity, and the sintered metal plate formed with the metal particle from which three types of particle sizes differ was arrange | positioned to this was demonstrated. However, the number of grooves may be an appropriate number depending on the size of the mold and the cavity. Further, the shape of the groove is not necessarily a square groove.
[0018]
Furthermore, the number of types of sintered metal plates does not have to be three, and may be one layer or four or more layers as long as the particle size of the sintered metal plates decreases as the distance from the cavity increases. .
[0019]
【The invention's effect】
As described above, according to the present invention, a sintered metal layer is formed in a resin molding die provided with a porous sintered metal layer for circulating a cooling medium or a heating medium in the vicinity of a molding cavity. Since the particle size of the metal particles to be used is large so that it is close to the mold cavity and small in the distant part, the flow rate of the medium that passes through the immediate vicinity of the mold cavity increases, and it cools (heats) uniformly in a short time. As a result, temperature unevenness can be reduced, and a high-quality resin molded product can be efficiently molded.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a structure of a resin molding die according to the present invention. FIG. 2 (a) is a front view of a mold body, (b) is a side view, and (c) is a bottom view. (A) is an isotherm diagram for explaining the operation, (b) is an isotherm diagram on the surface of a comparative mold [description of symbols]
DESCRIPTION OF SYMBOLS 1 ... Mold main body, 1a ... Molding cavity, 2 ... Cover body, 3 ... Cooling medium supply part, 4 ... Cooling medium discharge | emission part, 5, 6, 7 ... Sintered metal plate, 8 ... Groove cover, 9 ... Rib.

Claims (2)

In a resin molding die provided with a porous sintered metal layer for circulating a cooling medium or a heating medium in the vicinity of the molding cavity, the particle size of the metal particles constituting the sintered metal layer is determined by the molding cavity. A mold for resin molding, characterized in that it is arranged so that it is large in a portion close to, and small in a distant portion. 2. The resin molding die according to claim 1, wherein the sintered metal layer is formed by stacking a plurality of sintered plates having different particle sizes of metal particles.

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