JPH01184111A - Compression molding apparatus for thermosetting resin - Google Patents

Abstract

PURPOSE:To make it possible to carry out temp. control of a top force and a bottom force more precisely when a tablet is inserted, by providing an intermediate trunk mold made of a separate member between an upper trunk mold and a lower trunk mold and forming a tablet-inserting hole positioned on a bottom force and into which a top force is forwarded, on this intermediate trunk. CONSTITUTION:An upper heater wire 31 and an lower heater wire 32 are energized to heat an upper trunk mold 15 and a top force 11 and a lower trunk mold 24 and a bottom force 21 at specified temp. Under this condition, while the top force 11 and the upper trunk mold 15 are fitted together as they are, they are separated from an intermediate trunk mold 40 to open a table-inserting hole 45. A tablet prepd. by pressing a thermosetting resin powder is put therein and the top force 11 and the upper trunk mold 15 are set again on the intermediate trunk 40. Just before the resin material loses its fluidity, it is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a thermosetting resin, for example, a compression molding apparatus for a thermosetting resin used in molding an optical element made of a thermosetting resin such as a lens.

"Prior art and its problems" Conventionally, compression molding of thermosetting resin involves molding a powdered resin material into a tablet shape, which is then placed between an upper mold and a lower mold whose temperature is controlled to a predetermined temperature. This is done by compressing between the upper and lower molds. The wall thickness of the molded product is controlled by precisely weighing the amount of tablets corresponding to the wall thickness in the case of a closed mold, and in the case of a mold with a relief part for the tablet material, it is placed between the upper and lower molds. It was controlled by the pressure applied to the tablet and the distance between the upper and lower molds.

However, in such conventional compression molding equipment that uses an upper mold and a lower mold, when loading the tablet, the upper mold is separated from the lower mold and opened, so the mold temperature tends to drop, resulting in insufficient heating of the tablet or In some cases, compression molding was not performed well due to non-uniformity. In particular, in compression molding equipment of the type that stores the upper and lower molds in heated upper and lower molds, respectively, in order to control the temperatures of the upper and lower molds,
These upper body molds or lower body molds form a tablet insertion hole (a mold for regulating the outer periphery of the molded product). Therefore, when inserting the tablet, the upper mold must be removed from the upper body mold, and at this time, the temperature of the upper mold tends to fluctuate greatly due to changes in the surrounding environment.

Furthermore, when controlling the wall thickness of a molded product by precision weighing of a tablet, the weighing process itself is complicated and difficult. However, there is a problem in that complicated and expensive equipment is required to control these pressures and distances.

``Object of the Invention'' Therefore, an object of the present invention is to obtain a compression molding apparatus that can precisely control the temperatures of the upper mold and the lower mold. Another object of the present invention is to provide a device that allows for easy control of the wall thickness of a molded product and easy insertion of a tablet.

"Summary of the Invention" The present invention has an upper mold, an upper mold for storing and heating the upper mold, and a lower mold for storing and heating the upper mold, and a thermosetting resin is used between the upper mold and the lower mold. In a compression molding apparatus for compression molding, an intermediate body mold made of a separate member is provided between an upper body mold and a lower body mold, and a tablet insertion hole is provided in this intermediate body mold, which is located above the lower mold and into which the upper mold can enter. It is characterized by the formation of

According to this structure, since the tablet can be inserted into the tablet insertion hole of the intermediate body mold, the upper mold and the upper body mold can be separated from the intermediate body mold together when inserting the tablet, and
The lower mold and the lower body mold can be covered by the intermediate body mold, so that the temperature of the upper mold and the lower mold can be more accurately controlled when inserting the tablet.

In addition, the wall thickness of the molded product can be easily controlled by making it possible to adjust the relative axial position of at least one of the upper mold and upper body mold, and the lower mold and lower body mold using a spacer. .

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. FIG. 1 shows an embodiment of a compression molding apparatus for thermosetting resin according to the present invention. In this embodiment, the present invention is applied to an apparatus for molding lenses from thermoplastic resin, and the constituent elements have a rotationally symmetrical shape (circular cross section) about axis 0.

The upper mold 11 has a lower small diameter part 12 and an upper large diameter part 13, and a lens upper mold surface 12a is formed at the lower end of the small diameter part 12. I) Between the diameter portion 12 and the large diameter portion 13,
It constitutes a position regulating surface 14 perpendicular to the axis O.

This upper mold 11 can be inserted into and removed from the shaft hole 16 of the upper body mold 15. The shaft hole 16 has a small diameter hole 17 corresponding to the small diameter portion 12,
It consists of a large diameter hole 18 corresponding to the large diameter part 13, and a small diameter hole 1.
7 and the large diameter hole 18, a position regulating surface 19 perpendicular to the axis trio is formed. A spacer 20 is inserted between the position regulating surface 19 and the position regulating surface 14 of the upper die 11 to determine the axial position of the upper die 11 with respect to the upper body die 15. Further, an upper heater wire 31 for heating the upper body mold 15 is wound around the outer periphery of the upper body mold 15.

The lower mold 21 has a small diameter portion 2 corresponding to the small diameter portion 12 of the upper mold 11.
2, and a large diameter part 23 located below this small diameter part 22, and a lower lens mold surface 22a is formed at the upper end of the small diameter part 22.

This lower mold 21 is inserted into the shaft hole 25 of the lower body mold 24. The shaft hole 25 has a small diameter hole 26 corresponding to the small diameter portion 22,
It has a large diameter hole 27 corresponding to the large diameter part 23, and a small diameter hole 26.
A shallow recess 28 is formed in the upper end circumferential surface of. A lower heater wire 32 for heating the lower mold 21 is wound around the outer periphery of the lower mold 21.

The lower mold 21 and the lower body mold 24 both serve as a reference stand (bolster).
30, and their lower surfaces 33 and 34 serve as reference surfaces, respectively. And the reference surface 3 of the lower mold 21
A spacer 35 is inserted between the holder 3 and the reference stand 3o to determine the axial position of the lower mold 21 with respect to the lower body mold 24.

Between the upper body mold 15 and the lower body mold 24, there is an intermediate body mold 4
0 is located. This intermediate body mold 40 has a hole 42 into which the convex part 41 at the upper end of the lower body mold 24 fits, and a convex part 44 which fits into the hole 43 at the lower end of the upper body mold 15, The axes of the upper body mold 15 and the lower body mold 24 coincide with each other, and a tablet insertion hole 45 is further provided at the center thereof. This tablet insertion hole 45 is located above the lens lower mold surface 22a, and allows the small diameter portion 12 of the upper mold 12 to move forward and backward without a gap. The inner peripheral surface of this tablet insertion hole 45 constitutes a mold for the peripheral surface of the molded product (lens).

Note that the spacers 20 and 35 and their respective surfaces in contact with the front and back sides are all mirror-finished, and the spacers 20 and 35 are mirror-finished.
and 35 are prepared or formed in a plurality, each having a different thickness.

It is preferable that the upper mold 11, the upper mold 15, the lower mold 21, the lower mold 24, and the intermediate mold 40 are all made of the same material with a small coefficient of thermal expansion and good heat conductivity.

The present compression molding apparatus having the above-mentioned configuration is capable of forming the upper body mold 15 and the upper mold 11 by energizing the upper heater wire 31 and the lower heater wire 32.
, and the lower body mold 24 and the lower mold 21 are each heated to a predetermined temperature. In this state, the upper die 11 and the upper body die 15 are separated from the intermediate body die 40 while maintaining their fitting relationship, and the tablet insertion hole 45 is opened. At this time, the upper mold 11
maintains a fitting relationship with the upper body mold 15, so the temperature drop does not occur or is only slight, and the lower mold 21 and the lower body mold 2
Since the upper surface of the intermediate body mold 40 is covered with the intermediate body mold 40, there is no or only a slight temperature drop. That is, when the upper mold 11 is removed from the lower mold 21, the influence of the surrounding environment on the upper mold 11 is extremely small compared to conventional devices.

Then, a tablet made of hardened thermosetting resin powder is promptly inserted into the tablet insertion hole 45, and immediately thereafter, the upper mold 11 and the upper body mold 15 are set again on the intermediate body mold 40. At this time, the upper die 1 and the lower die 21 are prevented from approaching each other by the tablet.

The tablet to be introduced is slightly heavier than the final molded product, and is placed between the lens upper mold surface 12a and the tablet insertion hole 4.
5 and the lens lower mold surface 22a, and the recess 2
It is formed in advance using thermosetting resin material powder weighed slightly lighter than the weight of the molded product to be molded in the molding space 50 containing 8. In this way, it is easily possible to weigh within a certain range.

The tablet inserted into the tablet insertion hole 45 receives heat from the surroundings and eventually becomes soft. Upper mold 11 lower mold 2
1 starts just before the tablet becomes fluid due to heat. Then, the softened tablet gradually spreads in the molding space 50 formed by the lens upper mold surface 12a, the lens lower mold surface 22a, and the tablet insertion hole 45, and the fluidized excess resin flows into the recess 28. Pressure is applied at a position where the upper mold 11 is closest to the upper mold 15, that is, the lower mold 24, the intermediate mold 4o, and the upper mold 15 are in close contact, and the position regulating surface 14 of the upper mold 11, the spacer 20, and The position regulating surface 19 of the upper body mold 15 is in close contact with the reference base 3.
0, the spacer 35 and the reference surface 33 of the lower mold 21 are in close contact with each other, and the process ends just before the resin material loses its fluidity. Thereafter, the thermosetting resin material is polymerized to obtain a desired optical element (lens).

The thickness of this molded product (optical element) is the thickness of spacers 20 and 35.
N-tight control can be achieved by In other words, the thickness of the molded product is
This distance is determined by the distance between the lens lower mold surface 22a and the lens upper mold surface 12a, and this distance is determined by the distance between the spacers 20 and 35.
Can be set depending on the thickness. Position regulation surface 14
Although it is necessary to mirror finish the reference surface 33,
The distance between the position regulating surface 14 and the lens upper mold surface 12a, and the distance between the reference surface 33 and the lens lower mold surface 22a need only be measured accurately after processing, even if they are not accurate to the set values. The thickness of the spacers 2o and 35 can be easily processed to the order of 0.1 .mu.m, and therefore the grain size of the wall thickness of the molded product can be controlled within several .mu.m.

Note that by using both the spacers 20 and 35,
In the case of an optical element such as an optical disk pickup lens, in which the thickness can be controlled over a wider range and the concave portion 28 is thickened and actively formed as a flange portion (lens frame), the flange portion and lens portion This has the advantage that the positional relationship between the two can be determined with high precision. However, even if this is only done on one side, it is possible to control the thickness of the optical element to be molded.

"Effects of the Invention" As described above, the thermosetting resin compression molding apparatus of the present invention has the following features:
By using the intermediate body mold, when inserting the tablet, the upper mold and the upper body mold can be moved simultaneously without being separated, and the lower mold can be prevented from being exposed. Therefore, temperature fluctuations (decrease) between the upper and lower molds can be suppressed, and thermosetting resin can be compression molded at a more ideal temperature. Further, by adjusting the relative axial position of at least one of the upper mold and the upper body mold, and the lower mold and the lower body mold using a spacer, the thickness of the molded product can be set freely and accurately.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a compression molding apparatus for thermosetting resin according to the present invention. 11-... Upper mold, 12 a- Lens upper mold surface, 14-...
Position regulating surface, 15--Upper body type, 16--Shaft hole, 19
--Position regulating surface, 20--Spacer, 21--Lower mold, 22a--Lens lower mold surface, 24--Lower body mold, 2
5--Shaft hole, 30--Reference base, 31--Upper heater wire, 32--Lower heater wire, 33--Reference surface, 35-
...Spacer, 40--Intermediate body mold, 45--Tablet insertion hole, 50--Molding space. Patent applicant Asahi Optical Co., Ltd. Agent Kunio Miura Yoshimi Sasayama

Claims (1)

[Claims] (1) It has an upper mold, an upper mold for storing and heating the upper mold, and a lower mold and a lower mold for storing and heating the upper mold, and a thermosetting resin is used between the upper mold and the lower mold. In a compression molding device for compression molding, an intermediate body mold made of a separate member is provided between an upper body mold and a lower body mold,
A thermosetting resin compression molding apparatus characterized in that the intermediate body mold is formed with a tablet insertion hole located above the lower mold into which the upper mold can enter. (2) The thermosetting resin compression molding apparatus according to claim 1, wherein the relative axial position of at least one of the upper mold and the upper body mold, and the lower mold and the lower body mold is adjustable by a spacer. . (3) The upper mold and the upper body mold are formed with position regulating surfaces on which the front and back surfaces of the spacer come into contact, respectively.
A compression molding apparatus for the thermosetting resin described above. (4) The thermosetting resin compression molding apparatus according to claim 2, wherein a spacer is inserted between the reference table on which the lower mold and the lower body mold are placed and the reference surface of the lower surface of the lower mold.