JP2517762Y2 - Centering mechanism of injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a centering mechanism of an injection molding die, and can be used for an injection molding die for molding precision plastic products such as optical disk substrates.

[Background technology]

Conventionally, injection molding has been widely used as a method for manufacturing plastic products, and injection molding is exclusively used for molding precision plastic products such as optical disk substrates. Here, in the case of performing precision injection molding, it is necessary to maintain high positional accuracy such as the central axis when clamping the fixed mold and the movable mold that form the molding die, and between the molds. A centering mechanism is installed.

In FIG. 6, an injection molding die 60 has a fixed die 61 and a movable die 62, and a cavity 63 having a predetermined shape is formed between the respective dies 61 and 62 in the mold clamping state shown. Then, injection molding is performed by injecting the molten resin into the cavity 63 through the injection passage 64, and the movable mold 62 is separated to perform mold opening, and the molded product in the cavity 63 is taken out.

Here, a guide pin 65 is provided upright on the fixed die 61, and a guide sleeve 66 is formed on the movable die 62.When the die is clamped from the opened state, the guide pin 65 is inserted into the guide sleeve 66. Be guided. As a result, the movable die 62 is a fixed
It is moved to the correct position with respect to 61, and the desired mold clamping state is set.

Further, for precision injection molding, a centering mechanism 70 is installed between the fixed die 61 and the movable die 62 in order to ensure higher positional accuracy. As shown in FIG. 7, annular step portions 71 and 72 are formed on the opposite peripheral edges of the fixed die 61 and the movable die 62, and they are fitted to each other via a wear ring 73 when the die is clamped. . As a result, in the mold clamped state, reliable centering is performed so that the center axes Cf and Cm of the respective molds 61 and 62 coincide with each other.

[Problems to be solved by the device]

By the way, when performing precision molding with the injection mold 60 as described above, a fixed mold is used to control the quality of the molded product.
There may be a temperature difference between 61 and the movable mold 62.

If there is such a temperature difference, a general guide pin 65
With the guide method using the guide sleeve 66 and the guide sleeve 66, the influence of thermal expansion becomes large, and accurate centering becomes difficult.

On the other hand, if the annular step-type centering mechanism 70 is used, the cores are expanded uniformly in all directions, so core misalignment is unlikely to occur, but the expansion of the clearance of the fitting portion via the wear ring 73 increases or decreases with the expansion. Therefore, misalignment due to this gap is unavoidable.

Therefore, it is conceivable that an elastic material is used for the wear ring 73 to evenly absorb the increase or decrease in the gap between the annular step portions 71, 72 in all directions. However, with the wear ring 73 made of an elastic material, there is a problem in wear durability due to repeated fitting and disengagement, and problems such as generation of dust due to wear and eccentric load cannot be avoided, and are not suitable for precision molding. There was a problem.

The purpose of the present invention is to perform reliable centering and
An object of the present invention is to provide a centering mechanism for an injection molding die, which can prevent deterioration of accuracy due to temperature change and can improve wear resistance.

[Means for solving the problem]

According to the present invention, a plurality of fitting parts are provided in a mold-divided part of a mold for fitting in a concave and convex shape so as to be slidable in a radial direction of the mold. It is arranged so as to intersect with the central axis.

Here, as the fitting portion to be fitted into the concave and convex, a groove-like portion formed in each of the fixed die and the movable die forming the die and a projection portion fitted to this can be used. Then, it is desirable to form the unevenness of the fitting portion so that the radial dimension is larger than the circumferential dimension so that the influence of thermal expansion appears in the radial direction rather than in the circumferential direction.

[Action]

In the present invention as described above, the fitting portions of the fixed die and the movable die are engaged with each other when the die is clamped. At this time, the sliding direction of the plurality of fitting portions of each die intersects with the center axis of each die, and the center axis position of each die is uniquely determined by each fitting portion. Therefore, when the molds are clamped and the fitting portions of the respective molds are fitted into each other by projections and depressions, the center axes of the respective molds are aligned with each other and the centers of the molds are aligned.

Since the centering of each mold is defined by the sliding direction of each fitting part, even if different thermal expansion occurs between the fixed mold and the movable mold, each fitting part slides evenly in the radial direction. By moving, deformation and the like are alleviated, and there is no change in the centering accuracy. Therefore, the centering state is kept constant regardless of the temperature change, and it is possible to improve the wear resistance because it is not necessary to use the wear ring or the like by the elastic member unlike the conventional case, and the above-mentioned objects are achieved by these. It

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an injection molding die 10 of this embodiment has a fixed die 11 and a movable die 12, and each die 1 is in a clamped state as shown.
A cavity 13 having a predetermined shape is formed between the first and the second portions 12. Then, injection molding is performed by injecting the molten resin into the cavity 13 through the injection passage 14, and mold opening is performed by separating the movable mold 12, and the molded product in the cavity 13 is taken out.

The fixed die 11 and the movable die 12 are as shown in FIGS. 2 and 3, respectively. That is, the fixed mold 11 has a cylindrical shape fixed to the die plate 15, the movable mold 12 has a cylindrical shape fixed to the die plate 16, and the cavity 13 is at the center of each mold dividing surface 17, 18. It is formed.

A guide pin 21 is provided upright on the peripheral edge of the mold dividing surface 17 of the fixed mold 11, and a guide sleeve 22 is formed on the peripheral edge of the mold dividing surface 18 of the movable mold 12. Then, when performing mold clamping from the mold open state, the guide pin 21 is inserted and guided through the guide sleeve 22, the movable mold 12 is moved to an accurate position with respect to the fixed mold 11, and the desired mold clamping state is obtained. It is supposed to be done. With these, the guide pin type mold clamping guide mechanism
20 are configured.

A centering mechanism 30 according to the present invention is formed between the fixed mold 11 and the movable mold 12 in order to secure higher axial center accuracy.

As shown in FIGS. 4 and 5, annular step portions 31 and 32 are formed on the peripheral edges of the facing mold dividing surfaces 17 and 18 of the fixed die 11 and the movable die 12, and they have the same diameter. Butt to be continuous with each other when clamping.

In the step portion 31 of the fixed mold 11, a plurality of convex members 33 are arranged at predetermined intervals in the circumferential direction. The convex member 33 has a protrusion on the surface.
34, the protrusion 34 extends in the radial direction up to the central axis Cm of the fixed mold 11.

In the step portion 32 of the movable mold 12, a plurality of concave mold members 35 are arranged at positions corresponding to the concave mold members 33. The groove-shaped member 35 has a groove portion 36 that longitudinally cuts the surface, and the groove portion 36 is capable of inserting and fitting the protrusion portion 34, and is arranged so as to extend in the radial direction toward the central axis Cf of the fixed mold 11. There is.

The ridges of the protrusions 34 and the openings of the grooves 36 are chamfered, and the protrusions 34 are easily inserted into the groove 36 when the fixed mold 11 and the movable mold 12 are clamped, and the convex molds are formed. The member 33 and the concave member 35 are adapted to be fitted in a recess and projection. At this time, the convex member 33 and the concave member 35 are immovable in the circumferential direction due to the fitting of the protrusion 34 and the groove 36, but are slidable in the continuous radial direction.

In this embodiment, the movable die 12, which approaches the fixed die 11 during the die clamping operation, is a guide pin type guide mechanism.
It is guided by 20 in a substantially constant state. And
When the movable die 12 further approaches the fixed die 11, the tip of the protrusion 34 of the convex die member 33 is inserted into the groove portion 36 of the concave die member 35, and the center alignment between the fixed die 11 and the movable die 12 is a concave-convex fitting type. Accurately performed by the centering mechanism 30.

Here, in the convex mold member 33 of the fixed mold 11 and the concave mold member 35 of the movable mold 12, the protrusion 34 and the groove 36 are formed in the direction toward the central axes Cf and Cm of the molds 11 and 12, respectively. Since the respective directions are matched by the fitting, the central axis lines Cf, Cm of the molds 11, 12 also match, and reliable centering is performed in the mold clamped state.

According to the present embodiment as described above, when the fixed mold 11 and the movable mold 12 are clamped, the convex mold member 33 and the concave mold member 35 are engaged with each other by concavo-convex fitting so that the center axes Cf and Cm of the respective molds 11 and 12 are reduced. Can be aligned on the same axis, and accurate alignment of the molds 11 and 12 can be performed.

At this time, the protrusions 34 and the grooves 36 that are actually fitted between the convex member 33 and the concave member 35 are chamfered at the corners, respectively, so that they can be smoothly inserted into each other during fitting. It can be something.

Further, since the guide pins 20 are used to guide the molds 11 and 12 prior to the centering by the centering mechanism 30 as described above, the protrusion 34 and the groove 36 can be easily inserted. be able to.

On the other hand, since the convex member 33 and the concave member 35 of the centering mechanism 30 are slidable in the radial direction, even if different thermal expansions occur between the fixed mold 11 and the movable mold 12, they are even in the radial direction. By sliding, deformation and the like are alleviated, and deterioration of centering accuracy can be prevented in advance.

Therefore, even when a temperature difference is created between the fixed die 11 and the movable die 12 as in the case of molding an optical disk product, a decrease in centering accuracy due to a difference in thermal deformation is extremely small, and high molding accuracy can be secured.

Further, since the centering accuracy of the fixed mold 11 and the movable mold 12 can be kept constant regardless of the temperature state, it is not necessary to use a wear ring or the like made of an elastic member unlike the conventional case, so that the wear resistance can be improved and the wear can be improved. It is possible to solve problems such as dust generation and eccentric load due to the above, and it is possible to realize optimum centering for precision molding.

Here, the effect of improving the centering accuracy according to the present embodiment will be described with specific numerical values.

When manufacturing an optical disk substrate with a diameter of 130 mm, when using a guide mechanism 20 having four guide pins 21 at a position with a radius of 100 mm from the center of the injection molding die 10, the dimensional tolerance of the guide pins 21 is ± 1 μm. If the eccentricity between the fixed die 11 and the movable die 12 is set to 5 μm or less, the guide pin
The mounting position accuracy of 21 must be within ± 2 μm.

However, when manufacturing an optical disk substrate, the fixed type
It is necessary to make a temperature difference between 11 and the movable die 12, and the guide mechanism 20 by the guide pin 21 is deformed due to thermal deformation.

For example, the position of the guide pin 21 is 2.6 per 1 degree of temperature difference.
If the temperature difference is 2 degrees, the dimensional tolerance of the guide pin 21 must be 5.2 μm or more, and the eccentricity is 5 μm with or without such a temperature difference. It is difficult to set the following, and sufficient alignment accuracy cannot be ensured only with the guide pin 21.

On the other hand, in the centering mechanism 30 according to the present invention, the projection 34 and the groove 36, which are fitted in the concavo-convex structure, are not related to the thermal expansion in the radial direction due to the mutual sliding, and only a slight thermal expansion in the circumferential direction is considered. do it. Here, the radial length of the protrusion 34 is
If the width in the circumferential direction is 30 mm and the width in the circumferential direction is 10 mm, the expansion in the radial direction is absorbed by sliding, and the amount of thermal expansion in the circumferential direction is even with a temperature difference of 2 degrees.
0.26μm, the circumferential dimensional tolerance of the protrusion 34 is ± 1μ
m, and the mounting position accuracy is ± 2 μm or less, the temperature difference is 4
Even if the degree is increased, the eccentricity can be suppressed to ± 2 μm or less.

It should be noted that the present invention is not limited to the above-described embodiment, and the specific shape and size of the centering mechanism 30, the number and position of the centering mechanism 30 and the like may be appropriately selected for implementation.

Whether or not the guide mechanism 20 of the guide pin type is used together may be appropriately selected in practice, and the type of the guide mechanism 20 used together is also arbitrary.

Further, the use, type, size, shape, etc. of the injection mold 10 to which the present invention is applied are arbitrary, and the present invention can be applied to various injection molds and can exhibit excellent effects. .

[Effect of device]

As described above, according to the present invention, it is possible to perform reliable centering by arranging the concave and convex engagements that slide in the radial direction in a plurality of directions, and even if there is a temperature change, the core can be moved by the radial sliding. The accuracy can be prevented without affecting the alignment. Further, it is not necessary to deal with the conventional wear ring using an elastic member or the like, and it is possible to improve wear resistance and perform optimum centering for precision injection molding.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a perspective view showing an exploded state of the same embodiment, FIG. 3 is a perspective view showing an exploded state of the same embodiment, and FIG. 1 is a sectional view taken along line IV-IV, FIG. 5 is a sectional view taken along line VV of FIG. 4, FIG. 6 is a sectional view showing a conventional example, and FIG. 7 is a sectional view showing the conventional example. It is a figure. 10 …… Injection mold, 11 …… Fixed mold, 12 …… Movable mold,
17,18 …… Mold split surface, 30 …… Centering mechanism, 33 …… Convex member, 34 …… Projection part, 35 …… Concave member, 36 …… Groove part.

Claims (1)

(57) [Scope of utility model registration request] 1. A mold split portion of a mold has a plurality of fitting portions for fitting in a concave and convex shape so as to be slidable in a radial direction of the mold in a clamped state. A centering mechanism for an injection molding die, which is arranged so as to intersect with a central axis of the die.