JP2926301B2 - Thermoforming method and apparatus for thermoplastic resin sheet - Google Patents

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 thermoforming a thermoplastic resin sheet material or a fiber-reinforced composite sheet material mainly comprising a thermoplastic resin (hereinafter, these are collectively referred to as thermoplastic resin sheets). About.

[0002]

2. Description of the Related Art As a heat molding method in thermoplastic resin sheet molding currently in practical use, a method using a far-infrared heater having a maximum energy wavelength of about 4 μm used for vacuum pressure molding or the like, or GMT (glass mat thermoforming). Sheet) A method using a heating furnace using a hot air / far-infrared heater or the like used for molding or the like can be used.

[0003]

The heat molding method using a far-infrared heater having a maximum energy wavelength near 4 μm is effective for heating the resin because the output wavelength of the heater and the absorption wavelength of the resin substantially coincide. However, in the case of a thick material, the output wavelength of the heater is absorbed by the surface layer of the resin, so that it hardly penetrates into the material, and the temperature rise inside the material is dominated by heat conduction from the material surface. In general, the heat conduction of resin is lower than that of metal, so it takes time to heat the inside of the material to the moldable temperature with a far-infrared heater whose maximum energy wavelength is around 4 μm. It may rise too much and cause discoloration due to foaming and oxidation.

On the other hand, in a heat molding method using a heating furnace using a hot air / far-infrared heater or the like, energy is received by heat transfer on the material surface, and the temperature rise inside the material is increased by heat conduction from the material surface as in the above case. Becomes In this case as well,
Depending on the material, discoloration due to foaming and oxidation may occur.

In order to avoid these problems, it is necessary to carry out preliminary drying in a pre-heating step for a material having a water-absorbing property. Without the preliminary drying, foaming of the material occurs at the time of heating, and the properties of a molded article are significantly impaired. .

For example, in the case of polycarbonate as an example of a thermoplastic resin sheet, a preliminary drying step using a hot air oven is required before heating in order to absorb water in the air.

[0007] In view of the above problems, a main object of the present invention is to provide a method and an apparatus for thermoforming a thermoplastic resin sheet capable of avoiding discoloration due to foaming and oxidation of a material during heating. is there.

Another object of the present invention is to provide a method and an apparatus for heat-forming a thermoplastic resin sheet, which can omit a preliminary drying step.

Still another object of the present invention is to provide a method and an apparatus for heat-forming a thermoplastic resin sheet having a high energy saving effect.

[0010]

According to the present invention, there is provided a thermoplastic resin sheet material or a fiber-reinforced composite sheet material mainly comprising a thermoplastic resin (hereinafter, abbreviated as a material).
From, in the heat molding method of heat molding a three-dimensional molded article, the material was indirectly heated using a short-wavelength or medium-wavelength heater having a maximum energy wavelength of 1 to 3 μm, and was preheated to near the softening point of the material. The above material on the lower frame surface
And then contact the upper frame with the material,
While keeping the material warm with the upper and lower frames,
There line sterically molded by the upper and lower dies, the three-dimensional molding
When the material slides on the upper and lower frames,
Thus, a method for heat-forming a thermoplastic resin sheet characterized by being formed is obtained. According to the present invention
Main component material is thermoplastic resin sheet material or thermoplastic resin
Fiber reinforced composite sheet material (hereinafter abbreviated as material)
) To a hot forming method for hot forming three-dimensional molded products.
Above, the material is a thick material, and the maximum energy wave
Use a short or medium wavelength heater with a length of 1-3 μm
When heating the material indirectly, the output of the heater is increased.
The temperature in the thickness direction of the material can be reduced by
And the preheated flame near the softening point of the material
In a state where the above material is kept warm in the
A thermoplastic resin screen characterized by being molded.
Thus, a heat molding method for the sheet is obtained. According to the present invention,
Main composition of thermoplastic resin sheet material or thermoplastic resin
Fiber-reinforced composite sheet material (hereinafter referred to as material)
To form a three-dimensional molded product by heating
In the above, the closer the material is to the surface, the higher the thermoforming temperature
Laminated sheet with a maximum energy wavelength of 1 to
Using a short or medium wavelength heater of 3 μm
When the material is heated indirectly, the output of the heater is changed during heating.
Each part of the laminate sheet is raised by
To the moldable temperature suitable for each
The material is kept warm by the frame preheated near the softening point of
3D molding with a mold
The method of thermoforming a thermoplastic resin sheet, characterized in that
can get.

According to the present invention, there is also provided a thermoforming method for thermoforming a three-dimensional molded article from a thermoplastic resin sheet material or a fiber reinforced composite sheet material (hereinafter, abbreviated as a material) mainly composed of a thermoplastic resin. In the method, a movable clamp portion for holding the material at its end, a short-wavelength or medium-wavelength heater whose maximum energy wavelength for indirectly heating the material from both upper and lower surfaces or one surface thereof is 1 to 3 μm, Preheated near the softening point of the material,
While having a space for a lower mold in the center, a lower frame for holding the material in a warm state, and preheating near the softening point of the material, forming between the lower mold in the center A space for the upper mold to perform the heat treatment, and an upper frame for holding the material between the lower frame and the lower frame to keep heat, and the upper frame is sufficiently separated from the lower frame. Indirectly heating the material located between them at the upper and lower surfaces or one surface by the heater; retracting the heater from the space between the upper frame and the lower frame; Bringing the upper frame and the lower frame into a state of being held on one of the frame surfaces, and bringing the other of the upper frame and the lower frame into contact with the material And heating the thermoplastic resin sheet, comprising the steps of: molding the molded article with the upper and lower molds; and cooling the molded article between the lower mold and the upper mold. A molding method is obtained.

The heat forming apparatus according to the present invention is disposed above the lower mold for performing molding between the lower mold preheated below the softening point of the material and the lower mold; An upper mold preheated to a temperature lower than the softening point of the material, a vertically movable clamp portion disposed between the lower mold and the upper mold to hold the material at both ends thereof, A short-wavelength or medium-wavelength upper / lower heater which is disposed so as to be able to enter and exit the upper and lower space or one space of the material held by the clamp portion, and has a maximum energy wavelength of 1 to 3 μm for heating the material from its upper and lower surfaces or one surface Alternatively, one heater and the lower die are disposed adjacent to the lower die in a space below the raw material held by the clamp portion, and a central portion has an opening for the lower die, and softens the raw material. Around the opening And a lower frame for placing and holding the material, disposed in a space above the material held by the clamp portion, and having a central portion having an opening through which the upper mold can enter and exit, and a softening point of the material. An upper frame preheated to the vicinity and capable of sandwiching the material between the lower frame, a driving device for vertically moving the one frame or the upper and lower frames, and controlling an output of the upper and lower heaters or the one heater; And a control device that performs the control.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a molding process for heat-forming a box-shaped article from a thermoplastic resin sheet according to the present invention.
As shown in FIG. This embodiment is an example in which a lower mold and a lower frame are fixed. In FIG. 1, 1 is a thermoplastic resin sheet to be molded, 1 '(FIG. 6) is a molded product, and 2 is a box-shaped lower mold (hereinafter referred to as a female mold) in a fixed state. I will 3 is the upper mold (hereinafter referred to as male mold)
And is driven up and down hydraulically or pneumatically. The female mold 2 and the male mold 3 are preheated by a heater (a sheath heater, a cartridge heater, temperature-regulated water, steam, etc.) to a temperature lower than the softening point of the resin sheet 1.

Reference numerals 4 and 5 denote temperature gradients corresponding to the amount of the resin sheet 1 slipping into the female mold 2 during shaping, and the embedded density or flow rate diameter of heaters (seeds heater, cartridge heater, temperature regulating water, steam, etc.). Set by changing,
The upper frame 4 is attached to the slide guide of the male mold 3 via a guide and a rod by a frame (hot plate) preheated near the softening point of the resin sheet 1. The lower frame 5 is attached to the female mold 2. Reference numeral 13 denotes a clamper that holds the resin sheet 1 by sandwiching the resin sheet 1 at both ends.
Reference numerals 1 and 14 denote heaters for heating the resin sheet 1 from above and below in a vertical direction, and a short-wave or medium-wave heater in which the maximum wavelength is 1 to 3 μm, which is shorter than the far-infrared heater whose maximum wavelength is about 4 μm. It is.

FIG. 7 shows a heat molding apparatus provided with the above-mentioned components, and FIGS. 8 and 9 show a plan view and a side view thereof. This heating molding apparatus is a GMT molding apparatus 100 having an existing heating furnace.
It can be attached to 11 is an upper heater having a short wavelength or a middle wavelength, 12 is an upper heater rail for moving the upper heater 11 in and out of the molding area of the apparatus, 14 is a lower heater having a short wavelength or a medium wavelength, and 15 is a lower heater 14.
The lower heater rail 16 for taking in and out of the molding area, the upper heater 11, the lower heater 14, the upper heater rail 12, the lower heater rail 15, and the clamper 1
3 and has a structure in which the caster 17 can be easily attached to and detached from the existing GMT molding apparatus 100.

FIG. 10 shows the details of the heater section. Since the upper heater 11 and the lower heater 14 are the same except for the direction of the heater, FIGS. 10 (a) to 10 (c) show the area around the lower heater 14. It is illustrated. In FIG. 10A, reference numeral 21 denotes an inverter motor for driving a heater frame 26 to which the lower heater 14 is attached, which is connected to one end of a shaft 23 via a coupling 22.
As shown in FIG. 10C, a gear 24 fixed to the other end of the shaft 23 is arranged at one end of the lower heater rail 15. A chain 25 extends between the gear 24 and an idler 27 disposed at the other end of the lower heater rail 15. Since a part of the heater frame 26 is connected to the chain 25, the lower heater 14 is configured to be movable by rotation of the gear 24. FIG.
As shown in (e), the heater frame 26 has wheels 28.
And can move inside and outside the forming area along the lower heater rail 15. The upper heater 11 is similarly configured.

As a method of moving the heater,
Alternatively, a rodless cylinder system, a rack and pinion system, or a hydraulic or pneumatic cylinder with the tip of a piston rod fixed to the heater frame 26 for driving may be used, or another known driving system may be used. You can also. The chain system of this embodiment is more effective than other systems in terms of space and equipment costs.

FIG. 11 shows the details of the clamper portion. The clamper shown in FIG. 11 is located at both symmetrical left and right positions in FIG. 1 and clamps two opposite sides of the resin sheet. 31 is an air or pneumatic cylinder for operating a clamp, and operates a rack 33 and a pinion 34 via a floating joint 32;
The pinion 34 rotates a plurality of clamp plates 36 fixed at regular intervals to the shaft 35 via the shaft 35.
By providing a plurality of clamp bolts 37 each having a tapered tip at each clamp plate 36, the tip of the clamp bolt 37 is eroded by the resin sheet during clamping to prevent the resin sheet from slipping.

Reference numeral 38 denotes a clamp bolt 3 from the cylinder 31.
7 is a clamp base that has a built-in bush 40 for guiding the shaft 39, and is movable on the shaft 39 by applying a force in the direction of pulling the resin sheet by the coil spring 41. It has a simple structure. Reference numeral 42 denotes a clamp bar for manually moving the handle to move the clamp base 38 in the direction opposite to the direction in which the resin sheet is pulled, and has a mechanism capable of locking at the stroke end.

As a method of rotating the shaft 35,
Alternatively, the shaft 35 may be rotated by an inverter motor or an AC servomotor, an arm may be fixed to the shaft 35, and the arm may be rotated by the cylinder 31, or another known driving method may be used. Can also. As a method of moving the clamp base 38, a cylinder or a rack and pinion can be used instead of the coil spring 41. Further, as a method of moving the clamp base 38 in a direction opposite to the pulling direction of the resin sheet, a driving method such as a cylinder or a rack and pinion can be used, and if such a method is used, remote operation is possible. It is.

FIG. 12 shows details of one side of a mechanism for raising and lowering the upper heater 11 and the clamper unit. Reference numeral 45 denotes an air or pneumatic cylinder; 46, a guide connected to the output shaft of the cylinder 45; The upper heater 11 and the clamp unit move up and down on the shaft 47 fixed so as to extend in the vertical direction in 7).

FIG. 13 is a perspective view of a molded product on which the resin sheet 1 is molded, and a diagram of the upper frame 4 and the lower frame 5 with a temperature gradient. FIG. 13A is a perspective view of a molded product 1 ′. As is clear from the figure, the corners of the resin sheet 1 do not slip, and the middle part of the sides of the resin sheet 1 has the largest slip.

FIG. 13 (b) is a diagram showing the temperature distribution between the upper frame 4 and the lower frame 5, wherein the corners of the upper frame 4 and the lower frame 5 are only about 20 to 30 ° C. Temperature is low. FIG. 13C is a diagram showing a heater (seed heater) embedded in the upper frame 4 and the lower frame 5, and the corners of the upper frame 4 and the lower frame 5 have heaters as compared with other places. Are sparsely embedded.

FIG. 14 is a block diagram of a control device for controlling the outputs of the upper heater 11 and the lower heater 14 in the present heat forming apparatus. In FIG. 14, here, the upper heater 11
10D and FIG. 10D, respectively.
As shown in (e), the heater element 11-1 is composed of a number of rod-shaped heater elements 11-1 and 14-1 arranged in parallel to each other. A large number of heater elements in the upper heater 11 and the lower heater 14 respectively have three zones U1 and U
2, U3, D1, D2, D3.

An AC power supply AC is connected to the four non-contact relay units SSR1 to SSR4 for powering on and off. The heater elements belonging to the zone U1 on the upper heater side are all connected to the contactless relay unit SSR1, and the heater elements belonging to the zones U2 and U3 are all connected to the contactless relay unit SSR2. On the other hand, all heater elements belonging to zone D1 on the lower heater side are connected to contactless relay unit SSR3, and all heater elements belonging to zones D2 and D3 are connected to contactless relay unit SSR4.

Thus, the zone U1 and the zone U2
And U3, the zone D1, and the heater elements belonging to the zones D2 and D3 can be individually output controlled by the non-contact relay units SSR1 to SSR4. Actually, the contactless relay units SSR1 to SSR4 are respectively provided with cycle control units 61 to 6 described later.
The output control is performed by a combination of the power control unit 4 and the power control unit.

The control device also controls the heating of the resin sheet 1 during heating.
In order to detect the temperature of the radiation thermometer from both upper and lower sides thereof, two radiation thermometer measurement units 51-1, 52-1, 53-1 and 52-1 are provided above the upper heater 11 and below the lower heater 14, respectively.
54-1 is arranged. These radiation thermometer measurement units 51-1 to 54-1 are connected to radiation thermometer controller units 51 to 54, respectively. The outputs of the radiation thermometer controller units 51 to 54 are output from the A / D converter 56, respectively.
Are input to the CPU 60 through. Where A /
The output of the D converter 56 is digital data indicating the temperature T ₁ at the center of the sheet upper surface, and the output of the A / D converter 57 is digital data indicating the temperature T ₂ at the end of the sheet upper surface. Similarly, the output of the A / D converter 58 is digital data indicating the temperature T ₃ at the center of the lower surface of the seat.
D converter 59 is a digital data representing the temperature T ₄ of the seat bottom surface edge.

The CPU60, using the digital data representing the temperature T ₁ through T _4, a determination is made whether these values has reached all the values T _m which is determined in advance for each predetermined time, even one value if not reached T _m performs the following operation, the heater correction coefficient e ₁ of the upper center portion, the heater correction coefficient e ₂ of the upper end, the lower center portion of the heater correction coefficient e _3, the lower end heaters to calculate the correction coefficient e _4. Here, the heater correction coefficient e ₂ is a constant value 1
And

E ₁ = [1- (T ₁ -T ₂ ) / T ₂ ] e ₃ = [1- (T ₃ -T ₂ ) / T ₂ ] e ₄ = [1- (T ₄ -T ₂ ) / T ₂ ] The CPU 60 applies the heater correction coefficients e _{1 to} e ₄ calculated at regular intervals as described above to the contactless relay units SSR _{1 to} SSR ₄ via the output adjustment cycle control units 61 to 64, respectively. Output to Here, the cycle control unit 62 outputs a control signal so as to maintain a constant output since e ₂ = 1. The cycle control units 61, 63, and 64 respectively transmit control signals for controlling the output of the heater element to reduce the temperature distribution of the resin sheet based on the heater correction coefficients e ₁ , e ₃ , and e ₄ . S
Output to SR3 and SSR4. As described above, the value T
Feedback control based on _m is performed. In addition,
The temperatures T _{1 to} T ₄ are periodically stored in the internal memory in the CPU 60, and these values are displayed on the display 65 in a format such that the time variation can be recognized as necessary.

The setting unit 66, in addition to input the value T _m as described above, and inputs the data relating to the thickness and color of the resin sheet.
The reason why the color data is input is that the sensitivity of the radiation thermometer measurement unit changes depending on the color of the resin sheet.
The PU 60 detects the detected temperature T according to the input color.
Correction is performed by multiplying a predetermined color factor ₁ through T _4. As is well known, for example, a value such as 1.0 for white and 0.8 for black is used as the color coefficient. Further, as described later, when the material to be molded is a thick material or a laminated film, it is necessary to reduce or increase the output after a predetermined time from the start of heating. An output value, time, and the like necessary for such an operation are input.

FIG. 15 is a flow chart showing the flow of the operation when normal heating is performed by the above-described control device. In FIG. 15, a value _Tm is input from the setting unit 66 in step S1. When heating is started in step S2, in step S3, A / D
The temperatures T _{1 to} T ₄ from the radiation thermometer measurement units 51-1 to 54-1 input via the converters 56 to 59 are all values T.
Whether the determination reached _m is performed, it does not reach the value T _m proceeds to step S4. In step S4,
CPU 60 calculates the heater correction coefficient e ₁ to e ₄ by using the temperature T ₁ through T ₄ is performed in, CPU 60 has calculated the heater correction coefficient e ₁ to e _4, respectively, the cycle control unit for output adjustment 61 to 64 , Output to the non-contact relay units SSR1 to SSR4 to control the output of the heater. If necessary, the temperature T ₁ through T ₄ in step S5 is displayed displayed.
When step S4 ends, the process returns to step S3 and returns to step S3.
The determination operation is performed by the PU 60, and if all of the temperatures T _{1 to} T ₄ have reached the value T _m , the process proceeds to step S6, and the indirect heating operation by the upper heater 11 and the lower heater 14 ends.

Next, the operation of the heat forming apparatus according to the present invention will be described.

1) Setting the resin sheet (FIG. 1) The clamp bar 42 is manually turned to lock the clamp, and the clamp base 38 is adjusted to the clamp position (sheet width) of the thermoplastic resin sheet 1. Next, the resin sheet 1 is manually set on the clamp portion, and the cylinder 31 is operated, whereby the clamp plate 36 is rotated via the rack 33, the pinion 34 and the shaft 35, and the resin sheet 1 is held at two opposing sides. Clamp. At the time of clamping, the tips of the clamp bolts 37 bite into the resin sheet 1 to prevent the resin sheet 1 and the clamp plate 36 from slipping. After the clamping of the resin sheet 1, the clamp bar 42 is returned to its original position, so that a force in the tension direction of the resin sheet 1 is generated on the clamp base 38 by the spring 41,
Of the resin sheet 1, and even if the resin sheet 1 elongates during heating, it is prevented from sagging.

2) Heating of the resin sheet (FIG. 2) By the rotation of the inverter motor 21, the upper heater 11 and the lower heater 14 for indirect heating enter the molding area from outside the molding area of the apparatus, thereby heating the resin sheet 1. Do. Here, as described with reference to FIG. 14, the temperatures of the center and the end are measured in real time from above and below the resin sheet 1, and the temperature differences occurring in each part are calculated as heater correction coefficients e _{1 to} e ₄ .
Feedback is applied to the heater output according to the flow of the flowchart shown in FIG. The heating is terminated when the material temperature of each part rises to a previously input heating completion temperature.

3) Retreating the lower heater, lowering the upper heater and the clamper (FIG. 3) After the indirect heating of the resin sheet 1 is completed, the lower heater 14 is retracted out of the molding area by the rotation of the inverter motor 21.

After the lower heater 14 is retracted, the upper heater 11 and the clamper are lowered by the operation of the cylinder 45, and the resin sheet 1 is placed on the lower frame 5. Since the lower frame 5 has a built-in heater, the temperature of the resin sheet does not decrease even if the resin sheet 1 is placed on the lower frame 5.

4) Retreat of upper heater (FIG. 4) After the resin sheet 1 is placed on the lower frame 5, the upper heater 1
1 is retracted outside the forming area by the rotation of the inverter motor 21. The upper heater 11 may be retracted at the same time as the lower heater 14, and then the clamper may be lowered to place the resin sheet 1 on the lower frame 5.

5) Insertion of Resin Sheet (FIG. 5) The indirect heating of the resin sheet 1 is completed, and the male mold 3 is lowered at the same time when the upper heater 11 and the lower heater 14 are retracted. And the upper frame 4 interlocking the resin sheet 1 with the lower frame 5.

6) Molding and Cooling (FIG. 6) The resin sheet 1 is sandwiched between the upper frame 4 and the lower frame 5, and at the same time, the male mold 3 is moved down to press the resin sheet 1 against the female mold 2 and 1 is formed into the shape of a molded product 1 '. At this time, the upper frame 4 holds the sandwiching position of the resin sheet 1 by sliding the rod of the guide portion of the male mold 3.

Here, the upper frame 4 and the lower frame 5 are set in advance with a temperature gradient according to the amount of slip of the resin sheet 1 into the female mold 2 during shaping. In addition to the ease of cooling, the unnecessary slip-in portion is cooled to eliminate unnecessary slip-in, thereby ensuring the thickness of the molded article 1 'and preventing the occurrence of wrinkles.

Simultaneously with molding, the molded product 1 'is cooled to a temperature lower than the softening point (a temperature at which the resin can be released) by the female mold 2 and the male mold 3 preheated to a temperature lower than the softening point of the resin. After cooling, the upper frame 4 and the male mold 3 move upward to remove the molded product 1 '.

Table 1 below shows the characteristics of the short-wavelength and medium-wavelength heaters used in the present invention and the conventional far-infrared heater. Specific examples will be described with reference to Table 1.

[0043]

[Table 1]

Example 1 (Heating and Forming of Polycarbonate) When a polycarbonate sheet having a thickness of 3 mm, which has not been predried, is heated and formed using the present heating and forming apparatus,
First, the resin sheet 1 is clamped, the upper heater 11 and the lower heater 14 for indirect heating up and down are put into the molding area from outside the molding area, and the resin sheet 1 is heated from the upper and lower surfaces. The upper heater 11 and the lower heater 14 for the upper and lower indirect heating are medium wavelength heaters, and the heater temperature is set to about 1000 ° C., and the resin sheet 1 is heated to 170 ° C. by heating for 75 seconds. Immediately after the completion of the heating, the upper heater 11 and the lower heater 14 are retracted outside the molding area, and the clamper 13 sandwiching the resin sheet 1 is lowered to place the resin sheet 1 on the lower frame 5. Thereafter, the male mold 3 is lowered to perform molding. The resin sheet 1 having the added shape is rapidly cooled by the female mold 2 and the male mold 3 to a releasable temperature.

Example 2 (Heating of a Thick Material) When a material made of a resin sheet 1 having a thickness of 13 mm is heated using the present heating molding apparatus, the initial output is set to 100% using a short wavelength heater, and 100 seconds after heating. By reducing the output to 75%, more uniform heating in the thickness direction becomes possible.

FIG. 16 shows a comparison between a case where the output is 100% and a case where the output is changed on the way. As is apparent from FIG. 16, when heating is performed at a heater output of 100%, the temperature difference between the material surface and the material middle during molding becomes 50 ° C. On the other hand, if the heater output is changed so as to drop in the middle, the temperature difference is reduced to 25 ° C., and more uniform heating becomes possible.

Example 3 (Heating of a Sandwiched Foam Material) When a material made of a resin sheet in which a foam material having a thickness of 5 mm is sandwiched between upper and lower surface materials having a thickness of 1 mm is heated using the present thermoforming apparatus, a short time is required. Initial output 75 using wavelength heater
%, And the output is increased to 100% after 30 seconds of heating to prevent secondary foaming of the foamed material, and the surface material can be heated to a moldable temperature. The material temperature in this case is shown in FIG.

Example 4 (Heating of a material obtained by laminating a polyamide 66 film on a polyamide 6 material) A material was heated by a resin sheet 1 in which a 1 mm thick polyamide 6 was vertically laminated with a 0.2 mm thick polyamide 66 film. In this case, since the moldable temperature of the polyamide 66 is higher than that of the polyamide 6, if the resin sheet 1 is set to the moldable temperature of the polyamide 66, the base material of the polyamide 6 will be discolored by oxidation. When this material is heated by the present heat forming apparatus, the initial output is set to 75% using a short-wavelength heater, and the output is set to 100% after heating for 20 seconds.
By heating the base material polyamide 6 to 215 ° C. and the laminate film polyamide 66 to 230 ° C., it is possible to prevent discoloration due to oxidation of the material and raise the temperature of the material to a moldable temperature. Become. The material temperature in this case is shown in FIG.

In the above-described embodiment, the female mold 2 as the lower mold is fixed and the male mold 3 as the upper mold is movable. Conversely, the upper mold is fixed and the lower mold is fixed. May be movable. In this case, the upper mold needs to be a female mold and the lower frame 5 needs to be configured to be vertically movable. Also, both the female mold 2 and the male mold 3 may be movable molds. Also in this case, the frame (hot plate) of the female mold 2 is fixed to the female mold, and the clamper 13 is configured not to move up and down. Further, as for the upper heater 11 and the lower heater 14, when the lower mold (female mold) is movable, the upper heater 11 does not need to move up and down so that the lower heater 14 can move up and down. When both the male molds 3 are movable, the heater on the female mold side does not need to be moved up and down, and the heater on the male mold side is made up and down.

In any case, on the side where the heater is configured to be vertically movable, when the heater forms the resin sheet 1, the heater is retracted before or after the resin sheet 1 moves to the mold side. good. Further, the upper heater 11 and the lower heater 14
May be provided on one of the upper and lower sides. in this case,
The heater does not need to move up and down on the female mold side, and can move up and down on the male mold side.

[0051]

As described above, the present invention has been described by exemplifying several embodiments. However, in the heat molding method according to the present invention, the maximum energy wavelength which is shorter than that of the far-infrared heater whose maximum energy wavelength is about 4 μm is obtained. Has a following advantage because of using a short-wavelength or medium-wavelength heater having a thickness of 1 to 3 μm.

1) The temperature of the radiator (heater) is high, and the heating time can be shortened.

This is because the amount of radiation from the radiator to the radiated object (thermoplastic resin sheet) is large because the temperature of the heater is high, and the radiated object receives large energy.
Thereby, the heating time can be reduced.

The amount of infrared radiation is expressed by the following equation according to Stefan-Boltzmann's law.

Eb = A × 5.67 × ε × (T / 100) ⁴ where A is the area of the radiator, ε is the emissivity of the radiation source, and T is the absolute temperature of the radiation source. The higher the temperature of the radiator, the greater the amount of radiation and the faster the temperature of the radiator increases.

2) Since the inside of the resin sheet is heated, uniform heating can be performed in a short time.

Since the maximum energy wavelength emitted from the radiator is short and has a high transmittance at the absorption wavelength of the thermoplastic resin, the radiant energy reaches the inside of the radiator. As a result, the temperature difference between the surface and the inside of the resin sheet can be reduced even with a particularly thick resin sheet.

In the conventional far-infrared heater, since the maximum energy wavelength emitted from the heater matches the absorption wavelength of the thermoplastic resin, the energy of the heater is absorbed only on the surface of the material, and the inside of the resin sheet conducts heat from the surface of the resin sheet. Temperature rise was dominant. For this reason, the temperature difference between the surface and the interior of a thermoplastic resin with poor heat conduction increases,
In order to set the internal temperature to the moldable temperature, the temperature on the resin sheet surface becomes too high, and there is a possibility that discoloration due to foaming and oxidation occurs on the resin sheet surface.

On the other hand, in the present heat molding method, the temperature difference between the surface and the inside of the resin sheet can be reduced, the time from heating to molding is shortened, and the temperature is maintained by a temperature-regulated frame (hot plate). By minimizing the amount of temperature drop of the resin sheet, discoloration due to foaming and oxidation of the resin sheet can be avoided, and the temperature at which molding can be performed to the inside of the resin sheet can be achieved.

3) The heating rate of the heater is high, and arbitrary heating control is possible.

For heating the resin sheet, it is necessary to stabilize the heater temperature. In the case of the far-infrared heater as described in Table 1, it takes about 15 minutes for the heater temperature to stabilize. On the other hand, in the case of the short-wavelength and middle-wavelength heaters, it takes 2 seconds and 1 minute, respectively, until the heater temperature is stabilized. Since the rise time of the heater is short, it is possible to turn off the heater power outside the sheet heating time. As a result, power consumption during production is suppressed, and energy-saving production can be performed.

As described with reference to FIG. 14, the temperature distribution of the resin sheet being heated is measured, the set temperature of the heater in the portion where the temperature difference occurs is corrected, and the heater temperature is made to follow. It is possible to make the temperature distribution of the sheet uniform in real time.

For a thick material, it is possible to heat the material more uniformly in the thickness direction of the material by increasing the output of the heater in the beginning and lowering the output of the heater in the middle.

On the other hand, for a material in which a foamed material is sandwiched, the heater output is initially lowered to a temperature lower than the temperature at which the entire material is secondarily foamed, and then the heater output is increased to increase the surface material. It is possible to raise the temperature and perform the molding before the foamed material undergoes secondary foaming.

Similarly, for a material in which a different material is laminated on the surface, the heater output is lowered at first and the entire material is heated to a temperature lower than the temperature at which the base material is discolored by oxidation.
By increasing the heater output, it is possible to raise the temperature of the laminate material on the surface and perform molding before discoloration occurs due to oxidation of the base material.

4) Next, the heat forming apparatus according to the present invention
Casters are provided on the gantry and can be incorporated into existing GMT molding equipment and other equipment. Therefore, the switching to the main heat forming method is performed only by setting the main heat forming apparatus at a predetermined position of the GMT forming apparatus, and does not require modification of existing equipment.

5) Fig. 1
The tension mechanism of the resin sheet described in 1 is added,
The resin sheet is stretched during heating to prevent the resin sheet from sagging, prevent the resin sheet from contacting the lower heater and ignite, and keep the distance between the resin sheet and the heater constant. , And uniform heating of the resin sheet can be achieved.

6) In the heating / lowering apparatus of the present heating and molding apparatus, the upper heater is also linked, and the resin sheet is placed on the lower frame by lowering the clamp section to keep the resin sheet warm. The condition of the indirect heating from the upper heater (the distance between the upper heater and the resin sheet) changes, so that the temperature drop and the variation do not occur.

7) Further, the control device of the present thermoforming device is as follows:
By measuring the surface temperature of each part of the resin sheet in real time and applying feedback, a more uniform temperature distribution can be obtained. In addition, since the temperature distribution in the thickness direction of the resin sheet cannot be measured indirectly, the heater output is changed during heating according to the input of the thickness to reduce the temperature distribution in the thickness direction of the resin sheet. It is possible.

8) Further, the upper frame and the lower frame of the present heating device are provided with a temperature gradient according to the slip amount of the resin sheet into the mold in shaping the resin sheet. Can be controlled, the thickness of the molded product can be ensured, and the occurrence of wrinkles can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram around a mold for explaining a first step by a heat molding method of the present invention.

FIG. 2 is a schematic configuration diagram around a mold for explaining a second step according to the heat molding method of the present invention.

FIG. 3 is a schematic configuration diagram around a mold for explaining a third step according to the heat molding method of the present invention.

FIG. 4 is a schematic configuration diagram around a mold for explaining a fourth step according to the heat molding method of the present invention.

FIG. 5 is a schematic configuration diagram around a mold for explaining a fifth step according to the heat molding method of the present invention.

FIG. 6 is a schematic configuration diagram around a mold for explaining a sixth step according to the heat molding method of the present invention.

FIG. 7 is a view of the appearance of the thermoforming apparatus according to the present invention, as viewed from the inlet / outlet side of the heater.

FIG. 8 is a view of the heat molding apparatus of FIG. 7 as viewed from above.

FIG. 9 is a side view of a case where the heat molding device of FIG. 7 is incorporated into a GMT molding device.

10 is a diagram showing the upper heater and the lower heater shown in FIG. 7 together with their peripheral components, and FIG. 10 (a) is a diagram showing the heater moving mechanism as viewed from the front, and FIG. 10 (b). (C) is a diagram of FIG. (B) viewed from the side, (d) is a diagram of a portion of the upper heater viewed from the front, and FIG. () Is a view of a part of the lower heater as viewed from the front.

FIG. 11 is a view showing a clamp mechanism used in the present invention, and FIG. 11 (a) is a view of one of a pair of clampers as viewed from above,
FIG. 2 (b) is a partial cross-sectional side view of FIG. 2 (a) viewed from the side, FIG.
Is a view of a part of FIG.

FIG. 12 is a view for explaining an up-and-down driving mechanism of an upper heater and a clamp unit in the present invention.

FIG. 13 is a view for explaining slippage of an upper heater, a lower heater, and a resin sheet according to the present invention.

FIG. 14 is a block diagram for explaining a heater output control device according to the present invention.

FIG. 15 is a flowchart illustrating the operation of the control device shown in FIG. 14;

FIG. 16 is a characteristic diagram showing a relationship between a material temperature and a heating time when a thick material is formed according to the present invention.

FIG. 17 is a characteristic diagram showing a relationship between a material temperature and a heating time when a material laminated with a foam material according to the present invention is formed.

FIG. 18 is a characteristic diagram showing a relationship between a material temperature and a heating time when a film laminate material is formed according to the present invention.

[Description of Signs] 1 resin sheet 2 female mold 3 male mold 4 upper frame 5 lower frame 11 upper heater 12 upper heater rail 13 clamper 14 lower heater 15 lower heater rail 16 gantry 17 caster

Continuation of front page (56) References JP-A-4-144733 (JP, A) JP-A-63-25022 (JP, A) JP-A-5-274048 (JP, A) JP-A-1-27437 (JP) JP-A-5-269834 (JP, A) JP-A-5-274048 (JP, A) JP-A-5-293895 (JP, A) JP-A-6-23833 (JP, A) 3-150125 (JP, A) Actually open 1987-178130 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 51/00-51/46

Claims (18)

(57) [Claims] 1. A thermoforming method for thermoforming a three-dimensional molded product from a thermoplastic resin sheet material or a fiber reinforced composite sheet material (hereinafter, abbreviated as a material) mainly composed of a thermoplastic resin. Wavelength 1-3
indirectly heating the materials using a short wavelength or medium wavelength heater is [mu] m, preheated to near the softening point of the material under
Hold the material on the frame surface, and then
Contacting the frame, in a state was kept the material at the top and bottom of the frame, the row steric molded by upper and lower molds
During the three-dimensional molding, the upper and lower frames
A method for heat-forming a thermoplastic resin sheet, characterized in that the sheet is formed while sliding the rubber sheet. 2. A thermoplastic resin sheet material or thermoplastic.
Fiber reinforced composite sheet material mainly composed of conductive resin
Below, abbreviated as “material”)
Wherein the material is a thick material,
A short wavelength having a maximum energy wavelength of 1 to 3 μm or
When indirectly heating the material using a medium-wavelength heater,
By reducing the heater output during heating,
The temperature in the thickness direction is made uniform, and the
While keeping the material warm in the preheated frame,
It is characterized by performing three-dimensional molding with a mold
Thermoforming method for thermoplastic resin sheet. 3. A thermoplastic resin sheet material or thermoplastic.
Fiber reinforced composite sheet material mainly composed of conductive resin
Below, abbreviated as “material”)
In the heat molding method, the material is closer to the surface,
Laminated sheet with high thermoforming temperature, maximum energy
Energy wavelength is 1 to 3 μm
When the material is indirectly heated using a heater,
By increasing the force during heating, the laminating
Temperature of each part of the sheet to the appropriate moldable temperature
With a preheated frame near the softening point of the material
While keeping the material warm, perform three-dimensional molding with a mold.
Of a thermoplastic resin sheet characterized by being performed
Heat molding method. 4. The heating component according to claim 1,
Forming method, wherein said short or medium wavelength heater is
Ri by performing indirect heating from the upper and lower surfaces or one surface of the material
Rapidly heats only the material to the moldable temperature
Molding of thermoplastic resin sheet
Law. 5. The heat molding method according to claim 3, wherein
The upper frame and the lower frame slide the material during molding.
Characterized by having a temperature gradient according to the amount
A method for thermoforming a thermoplastic resin sheet. 6. A thermoplastic resin sheet material or thermoplastic.
Fiber reinforced composite sheet material mainly composed of conductive resin
Below, abbreviated as “material”)
That the heat molding process, the movable for holding the material at its ends class
Pump part and the maximum to indirectly heat the material from both upper and lower surfaces or one surface
Short wavelength or medium wave with energy wavelength of 1 to 3 μm
A long heater and preheated near the softening point of the material,
Having space and keeping the material warm
Lower frame for preheating near the softening point of the material and the lower mold in the center
It has a space for the upper mold to perform molding between
In addition, the material is sandwiched between the lower frame and the
The upper frame is sufficiently separated from the lower frame.
In the state, the material positioned between these
Step of indirect heating from both upper and lower surfaces or one side, and the heater between the upper frame and the lower frame
Retreating from a space, and removing the material from one of the upper frame and the lower frame.
And holding the other frame of the upper frame and the lower frame.
Moving the robot to a position where it contacts the material,
Performing molding with upper and lower molds, and cooling the molded product between the lower mold and the upper mold.
A thermoplastic resin sheet characterized by containing
Thermoforming method. 7. The heat molding method according to claim 6, wherein
The heater between the upper frame and the lower frame
In the step of retracting from the space, the top and bottom heaters
The thermoplastic resin sheet
Heat molding method. 8. The heat molding method according to claim 6, wherein
The heater between the upper frame and the lower frame
In the step of retracting from the space, one of the heaters
And the other heater is
Thermoplastic characterized by being moved toward the mold and retracted
Method for forming a conductive resin sheet. 9. The heat molding method according to claim 6, wherein
The heater between the upper frame and the lower frame
As a step to retreat from the space, the heater
If not provided, the heater is
At the same time, after moving to the mold,
The thermoplastic resin sheet
Heat molding method. 10. A thermoplastic resin sheet material or a thermosetting resin sheet.
Fiber-reinforced composite sheet material mainly composed of plastic resin
(Hereinafter abbreviated as “material”), the three-dimensional molded product is heated
In the thermoforming apparatus to be shaped, the lower mold is heated above the softening point of the material and the lower mold is arranged above the lower mold in order to perform molding between the lower mold and the lower mold.
Placed , the upper mold preheated below the softening point of the material, and the material is disposed between the lower mold and the upper mold.
Up and down movable clan for holding at both ends
And a space above or below the material held by the clamp portion.
The material is arranged so that it can enter and exit
Or the maximum energy wavelength for heating from one side is 1-3 μm
Short or medium wavelength upper and lower heaters or one
In the space below the material held by the clamp part.
It is arranged adjacent to the lower mold, and the center of the lower mold is
Pre-heating near the softening point of the material
To place and hold the material around the opening
Placed in the lower frame and the space above the material held by the clamp part
The central part has an opening through which the upper mold can enter and exit.
As well as being preheated to the vicinity of the softening point of the material,
Frame that can sandwich the material
And a drive for moving the one frame or the upper and lower frames up and down.
And an output of the upper and lower heaters or the one heater.
A thermoplastic resin sheet comprising a control device.
Heat molding equipment. 11. The heat molding apparatus according to claim 10, wherein
The upper and lower heaters or the one heater are
Divided into a number of heating zones, the control device
Including a plurality of energization control units connected to the heating area,
Each energization control unit can be individually output controlled.
The thermoplastic resin sheet characterized in that
Thermoforming equipment. 12. The heat molding apparatus according to claim 11, wherein
The control device may further include the upper and lower heaters or the one or more heaters.
The temperature of the material by heating the two heaters
At least one upper radiation temperature sensor for detecting from above
And at least one lower side detected from below the material
A radiation temperature sensor, the upper radiation temperature sensor and the lower
Preset based on the detection signal from the side radiation temperature sensor.
Predetermined while comparing with the set temperature
Calculate the heater correction coefficient for each energization control unit
And a control unit that calculates
Performing output control based on the heater correction coefficient.
Characteristic heat molding equipment for thermoplastic resin sheet. 13. The heat molding apparatus according to claim 12, wherein
The control device may further control the type and thickness of the material.
The output during heating of the short or medium wavelength heater.
To specify that it changes over time as desired
Has a setting unit, the control unit receives the signal from the setting unit
Therefore, the output control of the short wavelength or middle wavelength heater is
Thermoforming equipment for thermoplastic resin sheets characterized by performing
Place. 14. The method according to claim 10, wherein
In the thermoforming device, the clamp portion is attached to the material.
Features a mechanism to apply tensile force to
Thermoforming device for thermoplastic resin sheet. 15. The method according to claim 10, wherein
In the thermoforming device, the upper and lower heaters or the one
The heater is an upper and lower heater
The upper and lower space or
On the other hand, heat characterized by being able to enter and exit the space
Heat molding equipment for plastic resin sheets. 16. The heat forming apparatus according to claim 15, wherein
The upper and lower heater rails or one heater rail are
It is configured to be able to move up and down in conjunction with the clamp part
A thermoforming apparatus for a thermoplastic resin sheet. 17. The heat molding apparatus according to claim 16, wherein
The one heater is linked with the clamp unit and
Thermoplastic tree characterized by being configured to be movable down
Heat molding device for fat sheet. 18. The method according to claim 10, wherein
In the thermoforming device, the upper frame and the lower frame
Has a temperature gradient according to the amount of slippage during molding
A thermoforming apparatus for a thermoplastic resin sheet.