JPH09136327A - Method and apparatus for releasing plastic molding from mold by mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold releasing method which does not hurt a molding and a mold in demolding which is done by simple work. SOLUTION: A mold releasing method for a plastic molding consists of a mold setting process, a resin injection process in which a resin is injected into a set mold, a curing process in which the resin is cured by heating etc., and a mold releasing process in which a gap is formed between the mold and the molding by the difference in thermal expansion coefficients by cooling, steam is introduced into the mold, the mold and the molding are heated to enlarge the gap by the difference in thermal expansion coefficients, the gap is filled with the steam, a water layer is formed in the gap by the condensation of the steam, and the molding is separated from the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for releasing a molded plastic article after completion of curing by molding.

[0002]

2. Description of the Related Art Conventionally, in the case of a plastic molded product made of a mold, for example, a molded product made of a glass mold, a cavity formed between a glass mold composed of an upper die and a lower die is used. After injecting the resin and accelerating the curing reaction by heating, etc., take out the entire mold, treat the tape at the end part, put it on the heating conveyor and reheat it, and then put it on a vice table. A mold is placed on the mold, and the mold and the mold are separated from each other by the claws of the vise table and released from the mold to obtain the molded product (see FIG. 6).

[0003]

However, according to the above-mentioned prior art, when releasing the molded product from the mold, when the nail of the vise table is applied to the molded product sandwiched between the upper mold and the lower mold, In addition, if you press the nail too much, it will damage the surface of the molded product,
It is easy to become a defective product, and since the nail is advanced by the handle while pressing the mold against the fixed vise table by hand, if the vise table is slightly inclined in the front-back direction, Since the edge of the molded product hits the edge of the molded product, it falls off, and if the nail is forcibly inserted into the gap of the mold, the glass mold is easily broken by a shock at that moment. It was The present invention has been made in an effort to eliminate such drawbacks.

[0004]

The method of the present invention will be described. First, a molded mold is soaked in a cleaning liquid to remove dirt and the like from the surface to finish the surface clean.
Then, the process moves to the mold setting, where the upper mold 1 and the lower mold 2 are
A spacer is interposed between the two molds that form the above, and the periphery of the spacer is taped by tape 3 to form an edge surface, and a cavity for molding a molded product is formed between the molds. 4 (see FIG. 3).

Next, in the resin injecting step, a polymer raw material as a molding material is injected into the cavity 4, and when the polymer raw material is a thermosetting resin, methyl methacrylate is used.
, Diethylene glycol bisyl carbonyl, glycol dimethacrylate, diethylene glycol dimethacrylate and the like. In the case of a thermoplastic resin, PMMA, polycarbonate, polystyrene, polyacrylonitrile-styrene polymer, etc. are targeted.

Next, in the resin curing step, in the case of a thermosetting resin, in order to accelerate the curing reaction by heating, for example, a mold in which the resin is injected into the cavity 4 is put into a heating furnace and the inside of the furnace is charged. Is maintained at a high temperature sufficient for curing for a certain period of time to accelerate the curing reaction of the resin. Curing reaction of the resin proceeds by heating, and the resin cures along the shape of the cavity in which the upper and lower molds and the edge surfaces on both sides are surrounded by tape.

In the case of a thermoplastic resin, the resin is injected into the cavity after being heated and melted, and then cooled to accelerate the curing reaction.

When the above curing reaction is completed, in the case of a thermosetting resin, the molded plastic product 5 molded in the mold and its cavity is taken out from the heating furnace as it is, and the tape on the edge surface is removed. , Leave it at room temperature (see Fig. 4). This is the first cooling, and when the temperature falls from the high temperature heating furnace to room temperature of about 15 to 40 ° C., the mold and the molded product shrink in volume based on the temperature difference. Then, there is a large difference in the coefficient of thermal expansion between the mold and the plastic molded product. For example, in the case of a glass mold, the coefficient of thermal expansion of glass is 3 × 10 ^-6 to 2
On the other hand, the coefficient of thermal expansion of plastic is about 30 × 10 ^{-6 to} 310 × 10 ^-6, which is low at about 0 × 10 ^-6. The peeling action occurs due to the difference in volume change at the boundary surface of, and a slight gap occurs at the boundary surface between the two. However, this cooling is not limited to the outdoor, and after taking out from the heating furnace, it is directly transferred to the steam processing apparatus of the next step,
You may cool in the apparatus.

Further, in the case of the thermoplastic resin, since it is cooled in the curing step, the curing step and the cooling step proceed simultaneously.

Next, the mold containing the plastic molded product which has been subjected to the cooling step is put into the steam processing apparatus as it is.

In the steam processing apparatus, a steam jetting pipe is arranged in an upper part of a steam chamber in which a shelf for placing a plastic molded product is arranged, and a steam generator in which a combustion chamber and a water tank are formed is arranged outside the steam chamber.
A water supply pipe for supplying a predetermined amount of water is connected to the water tank.

The steam device is filled with steam, the room temperature rises due to the steam, and the mold and the plastic molded product expand in reverse. However, similar to the above, the expansion rate is different between them. Therefore, the volume changes again due to the expansion due to the temperature rise, and the gap caused by the peeling at the time of the cooling further increases. At that time, since the vapor has a property as a gas, it permeates into the gap between the mold and the molded product, and when the gap increases due to the above-mentioned volume change, the vapor permeates into even a small gap to fill the inside with vapor. .

Whether the steam used at this time is wet steam containing a large amount of water or dry steam with a small water content is adjusted depending on the properties of the mold and the plastic. For example, if the molded product is a non-hygroscopic glass mold and does not like burning due to high temperature, wet steam that does not exceed 100 ° C. is used. Use steam. The processing time in this steam processing apparatus varies depending on the conditions such as the thickness of the mold and the thickness of the plastic molded product, and is adjusted according to the conditions.

When this steam treatment is completed, the generation of steam in the processing apparatus is stopped and it is taken out of the room, or
Alternatively, the heating of the room is stopped to lower the room temperature. Then, the steam that has penetrated into the gap between the mold and the molded product is cooled, and dew condensation is changed to water, and as a result, a water layer is formed at the boundary between the two.

Now, when it is taken out of the steam processing apparatus as described above, it remains as it is, but when it is placed in the apparatus, steam is again generated in the steam processing apparatus, and like the above, the gap is increased by steam heating. Repeatedly filling the gap of steam with.
The number of times of this cooling-steam treatment is changed according to the conditions such as the mold and the thickness of the molded product, but it is usually sufficient to repeat 4 to 5 times. By repeating this cooling and steam treatment, the volume changes repeatedly between the mold and the molded product, and the gap between them is increased each time, and a water layer is formed on the boundary surface. It

Then, the water layer interposed between the two exerts an action of separating the two, and the upper mold and the lower mold can be separated by hand without touching the nail, and the entire mold can be separated. However, if there is a part that cannot be peeled off as it is, place the mold on the vise table and peel the molded product and the mold with the claws of the vise table. The gap between the molded article and the molded product is sufficiently increased, and the layer of water is present in the gap, and the two are in a separated state. It is easily peeled off and the peeling is completed.

After this, the molded product is sent to the inspection process, and the mold is moved to the cleaning process to prepare for reuse.

[0018]

[Embodiment of Apparatus] Next, an embodiment of the steam treatment apparatus will be described. Steam processing apparatus 1 used in the above-mentioned mold release method
As shown in FIG. 6, 0 is a steam chamber 11 having a constant volume.
A plurality of shelves 12 are formed in the steam chamber 11 for mounting the plastic molded product after resin curing and the mold thereof. A closed space is provided outside a door for putting in and out a mold to be placed on a shelf 12 in a part of the steam chamber 11, a steam ejection pipe 13 is arranged at an upper part thereof, and condensed water is arranged at a bottom part. The drain 14 for discharging the is disposed. The steam outlet pipe 13 is arranged in a meandering shape so that the steam outlet 13a is directed downward and the steam uniformly fills the interior of the room. A steam generator 15 is disposed outside the room. The steam generator 15 has a combustion chamber 16 at a lower part thereof, a water tank 17 formed on the combustion chamber 16, and a jet pipe 13 of the steam chamber 11 at the head. While arranging the connecting pipe 18,
The water supply pipe 19 for supplying a predetermined amount of water to the water tank 17 is connected to the water tank 17
Show inside.

【Example】

In molding a plastic lens,
Methyl methacrylate was selected as the thermosetting resin using a glass mold. The glass mold has a diameter of 80 mm and a thickness of 5 mm, and the same diameter has a thickness of 10 m.
The lower mold of m was used, and the thickness of the cavity was set to 30 mm. A tape machine was used to apply a pressure-sensitive adhesive tape including the edge surface to a thickness of 30 mm and set the mold. The above methyl methacrylate was injected into the cavity, placed in a heating furnace whose initial temperature was set to about 40 ° C, then heated to about 120 ° C and heated for about 20 hours to accelerate the curing reaction. did. After the resin was cured, it was taken out of the heating furnace and left at room temperature of about 35 ° C. for 5 minutes to peel off the adhesive tape attached to the mold. Next, this was put into a steam processing apparatus filled with wet steam, allowed to stand for about 20 minutes, and heated with steam. This was taken out and allowed to stand at room temperature of about 35 ° C. for about 5 minutes. As a result, the molded product was peeled from the mold while leaving 72 of 100 as they were, just by hand. About the remaining 38 pieces, they were peeled off on a vise table,
When the nails were applied, they were easily peeled off, and the release work was completed in a short time.

[0020]

As described above, according to the present invention, the peeling between the mold and the plastic molded product is promoted, and it is possible to prevent the plastic molded product from being scratched, cracked, or missing at the end. It is possible to suppress the defects, which conventionally had about 7 to 9%, to 1% or less, and to obtain an excellent effect that the yield is significantly improved. At the same time, it is possible to almost completely eliminate the accident that the mold is broken during the peeling work with the nail of the vise table. Further, in terms of the process, one process is added, but conversely, the labor-saving effect that the long time and labor required for the conventional mold releasing work can be reduced is exerted.

[Brief description of the drawings]

FIG. 1 is a flow chart showing a mold releasing method of the present invention.

FIG. 2 is a flowchart showing the mold releasing method of the present invention.

FIG. 3 is a vertical sectional view showing a state in which a mold is set.

FIG. 4 is a vertical cross-sectional view of a state in which a resin is injected into a mold and then cured.

FIG. 5 is a vertical cross-sectional view showing the device of the present invention.

FIG. 6 is a partially cutaway vertical sectional view showing a state where a mold is set on a vise table.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Tape 4 Cavity 5 Molded product 10 Steam processing device 11 Steam chamber 12 Shelf 13 Jet pipe 13a Jet outlet 14 Drain 15 Steam generator 16 Combustion chamber 17 Water tank 18 Connection pipe 19 Water supply pipe

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Reference number in the agency FI Technical display location B29K 101: 12

Claims (4)

[Claims] 1. A process of molding a mold in which a cavity is formed inside through a spacer or the like, and a resin injection for injecting a thermosetting resin into the cavity of the set mold. Process, a curing process of curing the resin by heating, etc., and a gap is created between the mold and the molded product by cooling, and then a space is filled with steam to heat both. And a mold release step of increasing the gap due to the difference in the coefficient of thermal expansion, permeating steam into the gap, and forming a water layer between the two by condensation of the steam after cooling to separate the mold and the molded product. And a method for releasing a plastic molded product. 2. A step of molding a mold in which a cavity is formed inside the mold through a spacer or the like, and a resin injection step of injecting a thermoplastic resin into the cavity of the set mold. And a curing step of curing the resin by cooling or the like, and a chamber is filled with steam to heat both of them to increase a gap due to a difference in coefficient of thermal expansion and to allow the steam to permeate into the gap and to form condensation of the steam after cooling. And a mold release step of forming a water layer between the two and separating the mold from the molded product, and a mold release method for a plastic molded product. 3. The method of releasing a plastic molded article according to claim 1, wherein the steps of cooling and steam treatment are repeated at least twice. 4. A steam jetting pipe is arranged above a steam chamber in which a shelf for placing a plastic molded product is arranged, a combustion chamber and a steam generator in which a water tank is formed are arranged outside, and the steam tank is located in the water tank. A steam treatment device with a water supply pipe connected to supply a fixed amount of water.