JPH02102009A - Pressure molding mold and pressure molding method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure molding method for, for example, a thermoplastic resin sheet, and a mold used in the method. It is useful in the field of pressure molding of required products.

(Prior Art) Conventionally, the following method 0 has been used as a pressure molding method for embossing an uneven shape onto a thermoplastic resin sheet.

(1) The thermoplastic resin sheet is heated in advance to near the thermal deformation temperature, and at the same time, the pressure molding mold is also heated to a certain temperature.

(2) A resin sheet is inserted into the mold and pressurized using a press or the like.

(3) Open the mold and take out the molded sheet.

The method (2) above has excellent productivity because the molding time is relatively short. However, since molding is performed near the thermal deformation temperature of the resin, distortion may occur during molding and the molded product may become deformed, or residual stress may remain in the molded product, causing deterioration over time. Therefore, this method is not suitable for pressure molding of products that require high precision, such as optical discs having minute irregularities.

Therefore, the following method (2) has been practiced, which enables high-precision molding by heating and cooling a thermoplastic sheet in a mold while pressurizing it.

(1) First, a thermoplastic sheet is inserted into a pressure molding mold.

(2) While applying pressure using a press or the like, the mold is heated to an appropriate temperature using a heat source such as a heater provided within the mold.

(3) Cool the mold to an appropriate temperature using the refrigerant circulation path,
Open the mold and take out the molded sheet.

If the temperature of the mold in step (2) above is selected appropriately according to various conditions such as the type of resin to be molded and the shape of the molded product, even if distortion and residual stress occur during molding, Since they are removed during the molding process, the resulting product is less likely to deform or change over time.

The conventional mold used in this pressure molding method (1) is one in which the heat source and the cooling medium circulation path are provided inside the mold to form an integrated structure.

(Problems to be Solved by the Invention) Although the method (2) mentioned above has the advantage of being able to obtain a molded product with high curling, it is necessary to pressurize and cool the resin to be molded while putting it in the mold. Therefore, when compared with method (2), the molding cycle was longer and the productivity was lower.

An object of the present invention is to provide a pressure molding method that allows high-precision molding and improved productivity, and a mold used in the method.

[Means to solve the problem]

As a result of intensive studies to achieve the above object, the present inventor discovered that separating the cooling means from the main body when heating the mold is very effective in terms of productivity. The invention has been completed.

That is, the present invention is the following pressure molding mold 1) and the following pressure molding method 2).

1) A main body (1) having a cavity surface and a heating source, a pressurized member (3) having a surface pressurized by a pressurizing device, and a pressurized member located between the main body and the pressurized member. , has a guide member (8) fixed to the main body and the pressurized member, and has a refrigerant circulation path, and is in contact and non-contact with the main body by sliding while being supported by the guide member. A pressure molding mold characterized by having a cooling member (4) capable of taking both states.

2) In a pressure molding method in which a thermoplastic material to be molded is inserted into a mold and heated while applying pressure, the mold according to claim 1 is used as the mold, and (a) #distribution body part (b) raising the temperature of the main body by the heating source while the main body and the cooling member are in contact with each other; (b) raising the temperature of the main body by the cooling member while the main body and the cooling member are in contact with each other; A pressure molding method comprising the step of lowering the mold temperature.

By using the mold of the present invention, the molding cycle can be shortened and productivity can be improved. The reasons for this will be explained below.

A conventional high-intensity pressure molding mold is an integrated mold in which a heating source and a coolant circulation path are provided inside, and thermal energy is applied to the entire mold during heating. In comparison, using the mold of the present invention, as in step (a) of the method of the present invention,
If the cooling member is separated during heating, thermal energy for raising the temperature of the cooling member becomes unnecessary, and the time required to raise the temperature of the mold can be shortened accordingly. Also, since the thermal energy stored in the mold during heating is small, the process (
The cooling time in b) can also be shortened by the amount of less thermal energy. Therefore, molding cycles are shortened and productivity is improved.

Hereinafter, the mold of the present invention will be explained in detail.

The mold of the present invention includes at least the above-mentioned "body part J,""pressurizedmember,""guidemember," and "cooling member."
It is a mold with Note that when the mold of the present invention is a mold consisting of an upper mold and a lower mold, only one of the upper mold and the lower mold may have the above configuration.

The "cooling member" as used in the present invention is a member having a refrigerant circulation path inside. The refrigerant is generally water, but oil,
Other liquids such as ethylene glycol or gases such as nitrogen or argon may also be used. The pattern shape of the refrigerant circulation path may be appropriately determined according to various conditions such as the shape of the mold, the type of molded product, and the type of refrigerant, and is not particularly limited. The shape of the cooling member may be any shape as long as it has a contact area large enough to cool the mold to a desired temperature when it comes into contact with the main body. A member having a shape (such as a flat plate) having a plane with a sufficient area is desirable from the viewpoint of processing, but other shapes may be used.

The "main body part" as used in the present invention refers to a member including a surface (cavity surface) that comes into direct contact with a thermoplastic molded material during molding. Furthermore, the main body in the present invention has a heating source as an essential component. The heating source is, for example, an electric heater, pressurized steam, or a high-frequency coil. In addition, any other structural members may be included, such as a fixing frame for fixing the cavity piece, a mold temperature sensor, and the like. In addition, when the mold of the present invention is a mold consisting of an upper mold and a lower mold, one of the upper mold and the lower mold has the essential constituent elements of the present invention, and the other mold may include a mold temperature sensor. Further, the main body part may naturally be a one-piece body, but it also includes a case where the parts that can be separated and disassembled are in contact with each other and thus appear to be a one-piece body.

The "guide member" as used in the present invention is, for example, a guide rod, but is not limited thereto, and may be, for example, a tapered block, a rack and pinion, or the like. When using a plurality of guide rods having a cylindrical shape or the like as this guide member, a through hole corresponding to the cross section of the rod is formed in the cooling member, and the guide rod is passed through the through hole to ensure good sliding. It is desirable to do so.

The pressurized member has a surface that is pressed by a pressurizing device (press device) and is a member for holding one end of the guide member, and its shape is not particularly limited.

Next, the pressure molding method of the present invention will be explained in detail.

The pressure molding method of the present invention includes: (a) raising the temperature of the main body by the heat source while the main body and the cooling member are in a non-contact state; (b) the main body and the cooling member; The main feature is that the method includes a step of lowering the mold temperature by the cooling member while the cooling member is in contact with the cooling member.

To bring the cooling member into contact and non-contact states as in steps (a) and (b), some driving means may be used to slide the cooling member. The driving means may be provided outside the mold or inside the mold, and may include, for example, an air cylinder, a hydraulic cylinder, a second mold clamping device, and the like.

The "non-contact state" in step (a) refers to a thermal non-contact state in which thermal energy from the main body is not transmitted to the cooling member to the extent that the effects of the present invention are achieved, and the position is completely It also includes a state in which they are not separated and are slightly in contact to the extent that the transfer of thermal energy is not a substantial problem.

Furthermore, if a temperature sensor is provided in the main body, it is desirable that the timing of driving the cooling member be controlled by a signal from the temperature sensor.

In step (a), the mold is heated to a desired temperature, and the temperature is such that the resulting molded product will not undergo significant deformation or change over time, depending on the type of thermoplastic material to be molded and It may be selected as appropriate depending on various conditions such as the shape of the molded product. Therefore, the optimal value for the mold temperature varies depending on the conditions, but for example, when using polycarbonate resin, 125°C to 240°C is desirable, and when using polymethyl methacrylate resin, it is desirably 125°C to 240°C. 15℃~180
°C is preferred.

The "contact state" in step (b) refers to a state in which the cooling member is in contact with the main body to the extent that the cooling action is sufficiently applied.

In the method of the present invention, usually step (a) and step (b)
) may be performed once in order, but the present invention is not limited thereto, and step (a) may be performed in one molding cycle.

This also includes cases where (b) is repeated or the order is reversed.

By the method of the invention described above, e.g. polycarbonate,
Various thermoplastic materials such as polymethyl methacrylate and polyvinyl chloride can be formed with high precision. In addition,
The thermoplastic material is not limited to a sheet shape, and its molding is not limited to the formation of fine irregularities, but it is possible to obtain molded products of various shapes.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 FIG. 1 is a sectional view showing an example of the mold of the present invention.

The mold of this embodiment consists of an upper mold and a lower mold, both of which have the same configuration except that the fixed frame 6 of the lower mold is provided with a temperature sensor 12.

The upper and lower molds of the mold of this embodiment include a cavity piece 7 whose surface has an uneven shape corresponding to the shape of the desired molded product, a cavity fixing frame 6 that supports the cavity piece 7, and a cavity fixing frame 6 that supports the cavity piece 7. It has a heating plate 5 which is pressed against the fixed frame 6 and is equipped with a heater for heating the mold. In addition, in this example,
The main body 1 includes the cavity piece 7 and the cavity fixing frame 6.
and a heating plate 5. Further, in the upper and lower molds of the present embodiment, the receiver as a pressurized member whose surface is pressurized by the pressurizing device has a plate 3, and the heating plate 5 and the receiver have a plate 3. It has a guide rod 8 located between and fixed thereto, and is movable supported by the guide rod, and has a cooling plate 4 having a built-in cooling circulation path. Further, an air cylinder 10 is built into the receiver plate 3, and the rod 9 of the air cylinder 10 is connected to the cooling plate 4, so that the cooling plate 4 can be driven by the air cylinder 10.

The mold of this example has the above configuration.

The receiver is used by fixing the plate to the fixed plate 2 of the press device 13.

Next, the following pressure molding was performed using the mold of this example.

First, as shown in FIG. 1, the diameter is 130 mm and the thickness is 1.
A 2 m@ disc-shaped polycarbonate sheet 21 was inserted into the mold.

Next, as shown in FIG. 2, the mold is clamped by the power of the press device 13, and the resin sheet 21 is
A pressure of 2 was applied. Then, at the same time as the mold was closed, the heater in the heating plate 5 was activated to heat the mold so that the mold temperature detected by the temperature sensor 12 reached a peak of 200°C.

Next, the heater in the heating plate 5 is turned off to stop the temperature rising so that the temperature decreases from the peak of 200°C, and at the same time, as shown in FIG. 3, the air cylinder 10 is activated to heat the cooling plate 4. The mold was pressed against plate 5 and cooled.

After cooling, the mold was opened using the press device 13 and the molded product was taken out. Further, at the same time as the mold was opened, the cooling plate 4 was moved by the air cylinder 10 and separated from the heating plate 5.

By pressure molding as described above, the width is 2.5±
0. O1ga, depth 0.3±0. Old μ, pitch 12±0
．． An S molded product having a highly accurate uneven shape of 1 μm was obtained.

Furthermore, the relationship between the mold temperature sensed by temperature sensor +2 and the molding cycle during the molding is shown by line A in FIG. As is clear from this, the molding cycle in this example is as short as 60 seconds to 70 seconds.

Comparative Example 1 The same mold as in Example 1 was used, except that the cooling plate 4 and the heating plate 5 were kept in pressure contact with each other, and the cooling plate 4 was not moved, as in the conventional mold. Pressure molding was performed at 200°C.

The relationship between the mold temperature sensed by the temperature sensor 12 and the molding cycle during the molding is shown by line B in FIG. As is clear from this, the molding cycle in this comparative example is as long as 100 seconds to 120 seconds.

Embodiment 2 FIG. 4 shows a configuration in which a second mold clamping device 41 provided in the press device 13 is used instead of using the air cylinder 12 as the driving means, and the other components are the same as in Embodiment 1. FIG. Even if the mold in this example is used, good pressure molding similar to that in Example 1 is possible.

(Effects of the Invention) As explained above, by using the mold of the present invention and performing the method of the present invention, high-intensity pressure molding with a short molding cycle and improved productivity is possible.

[Brief explanation of the drawing]

Figures 1 to 3 are cross-sectional views showing the mold of Example 1 and the pressure molding process using the mold, Figure 4 is a cross-sectional view of the mold of Example 2, and Figure 5 is a cross-sectional view showing the mold of Example 2. , Example 1 and Comparative Example 1
FIG. 3 is a diagram showing the relationship between mold temperature and molding cycle in molding.

Claims (1)

[Claims] 1) A main body (1) having a cavity surface and a heating source, a pressurized member (3) having a surface that is pressurized by a pressurizing device, and the main body and the pressurized member. and a guide member (8) fixed to the main body and the pressurized member, and has a refrigerant circulation path, and slides while being supported by the guide member. A pressure molding mold characterized by having a cooling member (4) capable of being in both a contact state and a non-contact state. 2) In a pressure molding method in which a thermoplastic material to be molded is inserted into a mold and heated while applying pressure, the mold according to claim 1 is used as the mold, (a) the main body portion and (b) raising the temperature of the main body by the heating source in a state where the cooling member is not in contact; (b) raising the temperature of the main body by the cooling member in a state in which the main body and the cooling member are in contact; A pressure molding method characterized by including a step of lowering mold temperature.