JPS6354525B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding and curing device for a structure manufactured from a so-called resin-based composite material, which is a combination of fibers and synthetic resin.

2. Description of the Related Art Conventionally, an autoclave molding apparatus is known as an example of a molding and curing apparatus for a structure formed of a fiber-reinforced resin using a resin-based composite material, such as glass fiber, organic fiber, carbon fiber, or the like. In this autoclave molding device, composite materials are stacked on a single-sided mold, then covered with a so-called bag made of a thin sheet of nylon, etc., the interior is kept in a vacuum, and then inserted into an autoclave and heated under pressure. Structures are manufactured by molding and curing composite materials. However, in this type of molding apparatus, a high-temperature gas flow is usually passed from the inlet of the autoclave toward the back of the autoclave, thereby heating the structure to be molded. For this reason, when molding particularly long or large structures using conventional autoclave molding equipment, the temperature on the autoclave inlet side of the structure is relatively high, and the temperature on the back side is relatively low. That is, there is a problem that the heating temperature distribution of the structure becomes non-uniform, and the temperature of the structure significantly lags behind the rise and fall of the temperature inside the autoclave. For this reason, the resin content of each part of the molded structure becomes non-uniform, resulting in variations in the distribution of strength and elastic modulus. Furthermore, because the temperature rise rate of the structure is uneven, the gelation time varies, resulting in uneven curing shrinkage strain and thermal expansion strain, and because the temperature cooling rate is uneven, thermal shrinkage strain becomes uneven. This results in non-uniformity, and the difference in these thermal strains causes molding cracks or molding distortions, which is a drawback.

In addition, in the above-mentioned conventional molding equipment, since the resin flow state and timing of the structure to be molded are unknown, voids remaining in the structure during the lamination process and the curing reaction of the resin of the structure This method has disadvantages in that blisters generated during the process cannot be removed and it is difficult to determine whether the structure has been completely cured.

Therefore, the purpose of the present invention is to uniformize the temperature distribution during heating and cooling of resin composite structures, to equalize the resin content, to minimize molding distortion, and to prevent molding cracks, thereby improving quality and reliability. A resin system using an autoclave molding method that can obtain a structure with improved molding quality, as well as remove the voids and blisters mentioned above, and uniformly and completely cure the resin. An object of the present invention is to provide a molding and curing device for a composite material structure.

In order to achieve the above object, the apparatus for molding and curing resin-based composite structures according to the present invention is provided with heating means consisting of a large number of heater elements that independently heat each part of the structure and its control means, controlling the heating means so as to make the temperature of each part of the structure uniform during heating and cooling while at the same time performing relative control of the pressure inside the autoclave and the pressure inside the bag by the control means; The resin properties such as the initial fluidization time and gelation start time of the resin at a plurality of predetermined locations are electrically detected, and the temperature control cycle and the temperature control cycle by the temperature control means and the pressure control means are performed based on the electrical signals indicating the resin properties. Characterized by adjusting the pressure control cycle.

According to the molding and curing apparatus for a resin composite structure of the present invention having the above-described structure, the temperature of each part of the structure is always uniform, especially by the heating device consisting of a large number of heater elements, the temperature detection device, and the control device. Therefore, the above-mentioned molding cracks and molding distortions do not occur in the structure manufactured by the apparatus of the present invention. Furthermore, we installed a device that detects the properties of the resin in the structure during pressurization and heating, that is, the initial fluidization time, and controlled the pressure cycle and heating cycle based on the detected properties of the resin. It is possible to remove voids, blisters, etc. therein, and furthermore, it is possible to completely and uniformly harden the resin, thereby improving molding quality.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A molding and curing apparatus for a resin-based composite structure according to a preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing the configuration of a molding and curing apparatus (autoclave) 1 for a resin-based composite material structure W according to an embodiment of the present invention.

The molding hardening device 1 is a single-sided type, that is, a molding jig 2
The structure W, which is a preform, is stacked and placed on the forming jig 2. This structure W is covered with a pressure bag, ie, a vacuum bag 3, which is a soft membrane. The inside of this vacuum bag 3 is
The structure W is kept airtight by the sealing material 4, and the internal air is removed and depressurized by the vacuum pump 6 communicated with the pipe 5, and the structure W is pressurized by the relative pressure difference with the pressure inside the autoclave 1. It's getting old. At the back of the autoclave 1, there is provided an in-can temperature regulating device 7 that raises and lowers the temperature inside the can, and this in-can temperature regulating device 7 consists of a cooler 8, a heater 9, and a fan 10. The temperature within the can is regulated by introducing a stream of cold or hot air into the can. In addition, in order to rectify the air flow inside the autoclave 1, the rectifying partition wall 1
1 is provided.

In order to directly heat the structure W inside the autoclave 1, a heating device 12 is arranged adjacent to the structure W inside the autoclave 1. This heating device 12 consists of a multi-heater 13 embedded in the molding jig 2 and a multi-heater 14 embedded in, for example, a heat-resistant rubber mat and placed over the structure W. The multi-heater 14
As shown in the figure, it consists of a large number of heater elements 14a that cover almost the entire surface of the structure W. Although the multi-heater 13 is not shown, it has the same arrangement as the multi-heater 14. Note that as this heater, when the molding pressure is low, it is desirable to use an infrared radiation type multi-heater, and a multi-heat pipe may also be used.

The above-mentioned can temperature adjustment device 7 and heating device 1
2 is connected to a temperature control power supply device 15, and operates upon receiving electric power from this power supply device 15. This power supply device 15 is capable of supplying power to each heater element 13a, 14a separately and independently, and is controlled by a control device 16 comprising a microcomputer with an input/output interface. Let's do it.

The pipe 5 is provided with an automatic control valve 17 for exhausting the air inside the bag 3 by the vacuum pump 6, and a branch pipe 19 with an automatic valve 18 for communicating the inside of the bag 3 with the atmosphere. It is provided. On the other hand, the autoclave 1 is provided with an intake pipe 20 and an exhaust pipe 21 for introducing high-pressure gas into the can, and these intake pipes 20 and exhaust pipes 21 have an automatic intake valve 22 and an automatic exhaust valve, respectively. 23 are arranged. The vacuum pump 6 and the automatic valves 17, 18, 22, and 23 are each connected to a pressure control power supply 24, and are individually controlled by receiving electric power from the power supply 24. This power supply device 24 is
It is controlled by the control device 16 to supply power to each valve and the like.

An in-can temperature detector 25 for detecting the temperature inside the autoclave 1 is arranged near the entrance of the autoclave 1 . Further, in order to detect the temperature of each part of the structure W, a structure temperature detector 26 is disposed close to the structure W. This temperature sensor 26
The sensor element 26a is composed of a large number of IC (iron constantan) or CA (chromel alumel) thermocouples arranged corresponding to each heater element 13a, 14a. Note that this sensor element 26a may be a thin film gauge type temperature detector, especially when the surface quality of the structure W is required, and in this case, it is desirable to use a foil lead wire. Note that the sensor element 26a on the lower side of the structure W is connected to the forming jig 2 as shown in the figure.
You can also embed it in Detectors 25 and 2
6 are each connected to a temperature-voltage converter 27, which converts the temperature into a sufficiently large electrical signal and outputs it to the control device 16.

On the other hand, a vacuum system pressure detector 28 is provided on the pipe 5 to detect the pressure of the vacuum system between the vacuum pump 6 and the bag 3.
An in-can pressure detector 29 is provided to detect the pressure inside the can. These pressure detectors 28 and 29
are connected to a pressure-voltage converter 30, which converts each pressure into a sufficiently large electrical signal and outputs it to the control device 16.

The control device 16 is composed of a microcomputer having an input/output interface for the above-mentioned multi-channel signals, and includes molding pressure control cycle data, heating rate, curing temperature, curing time, depressurization temperature, etc. data. A key input device 31 is provided for inputting temperature cycle data at any time. This control device 16 appropriately controls the pressurization and heating cycles of the structure W based on the cycle data, and also performs arithmetic judgment based on the input electric signal, thereby controlling the temperature control power supply device 15. and pressure control power supply device 24
In addition to controlling the pressure inside the can, the heater elements 13a and 14a are turned on and off so that the temperature of each part of the structure W matches a predetermined temperature inside the can.

Furthermore, the molding and curing device according to this embodiment determines the initial flow time and gelation start time of the resin of the structure W during heating, and performs the above-mentioned heating control cycle and pressurization control cycle depending on the properties of the resin. A resin property detector 40 is provided to obtain a function of automatically adjusting the amount in a more desirable direction.

The resin property detector 40 includes a pair of two thin electrode plates affixed to the surface of the structure W, or a set of two or three electrode wires affixed to the surface of the structure or inserted into the structure. Consisting of Note that the above electrode plate pair and electrode wire may be used alone or in combination, but the electrode plate pair is used for thin-walled parts, and the electrode wire is used for thick-walled parts, and is generally used when detecting internal conditions. . The detectors 40 are arranged at several locations of the structure W, such as a portion where the temperature rise is determined to be slowest, a portion where the temperature rise is determined to be the fastest, and an intermediate portion thereof, as shown in FIG. 4, for example. If the structure W uses a conductive material such as carbon fiber, the electrode should be covered with a porous insulating coating so that only the resin comes into contact with the detector electrode and the conductive fibers do not come into contact with it. , it is necessary to use it by covering it with, for example, cotton or synthetic fiber cloth. In this way, when the resin viscosity decreases due to heating, the resin soaks into the insulating film and comes into contact with the electrode.
Note that for any of the above-mentioned electrodes and their lead wires, thin electrode plates, thin electric wires, or foil-like electric wires are used so as not to cause harmful defects to the molded structure. Practically speaking, it is preferable to use materials with a thickness of approximately 0.1 mmt or 0.1 mmφ for both.

The resin property detector 40 detects changes in the properties of the resin by detecting changes in DC potential or electrical resistance that occur at the initial stage of the curing process of the resin of the structure W. This detector 40
is connected to a characteristic signal discriminator 41, which receives the characteristic signal from the detector 40 and processes it so that it can be input to the microcomputer of the control device 16. The control device 16 receives this property signal and corrects the above-mentioned predetermined heating cycle and pressurizing cycle based on it.

Hereinafter, the operation of the molding and pressurizing device of the present invention will be explained in detail, focusing on the operation of the control device 16, with reference to the flowchart of FIG.

First, in FIG. 3, a structure W, which is a preform, is placed on a forming jig 2, a temperature sensor 26 is placed on top of the structure W, and a structure W on which this temperature sensor 26 is placed is placed. Covers in a sealed state with Bug 3. In this state, the forming jig 2 is inserted into the autoclave 1. After that, the valve 18 is closed, the vacuum pump 6 is activated, (A) the autoclave 1 is closed, and the valves 17 and 23 are closed.
Release (B). After this predetermined time, it is determined based on the output of the vacuum system pressure detector 28 whether the degree of vacuum in the vacuum system, that is, in the bag 3 is sufficient (C).

When this determination is NO, the control device 16 is arranged to issue a vacuum leak alarm. For this reason,
It is desirable that the control device 16 be provided with an alarm (not shown). On the other hand, when this determination is YES, the temperature control power supply device 15 is activated, and the can temperature adjustment device 7 and the heating device 12 are
Heating is performed (R). This heating is performed while controlling the electric power of the heater elements 13a, 14a of each part in accordance with the temperature rise of the part of the structure W where the temperature rise is slowest. By this heating, for example, the structure W
When the resin viscosity changes as shown in FIG. 5, the resin property potential signal outputted by the resin property detector 40 changes as shown in FIG. 6. This potential signal causes the resin viscosity to become void, Sufficiently low viscosity to allow blistering (this is indicated by β in Figure 5)
Determine whether the value has fallen to (S). This viscosity is usually several tens of centipoise or less. After the viscosity of the resin has sufficiently decreased, the temperature and pressure inside the can, that is, the structure W, are optimally controlled for defoaming of the resin (T, U),
Gas components in the structure W are sufficiently removed. Whether this gas component has been sufficiently removed is determined by determining whether the temperature rise suppression time is sufficient.
Whether this temperature rise suppression time is sufficient is determined at the time when the potential signal reaches its maximum value, when its rate of increase begins to decrease, or at the time when a preset maximum setting time is reached. After the gas components in the structure W are completely removed as described above, the valve 18 is opened, and then the vacuum pump 6 is stopped. Then, high pressure gas is introduced into the can through the valve 22 to increase the pressure inside the can to a predetermined pressure (G). Note that the pressurization speed is generally more preferable, depending on the pressurization capacity of the device. In addition, the above-mentioned predetermined pressure is a constant pressure determined by the type of resin of the structure W and the type of the structure itself, and is generally a certain pressure.
Kg/ ^cm2 . When the pressure in the can is increased in this way and the pressure detector 29 detects that the pressure in the can has reached the predetermined pressure (H), the temperature control power supply 15 is activated to adjust the temperature in the can. The heating device 7 and the heating device 12 are restarted to heat the structure W (I). Thereafter, while the temperature detector 26 detects the temperature of each part of the structure W, each heater element 13a, 14a of the heating device 12 is controlled to adjust the temperature of each part of the structure W to a predetermined temperature. Raise the temperature to the same as the internal temperature and maintain this temperature for the specified curing time (J).
The pressure increase due to the expansion of the pressurized gas due to the temperature rise due to this heating and the pressure decrease due to the leakage of the pressurized gas are corrected by opening and closing the valves 22 and 23.
The pressure inside autoclave 1 is maintained and controlled at a predetermined molding pressure (K). This control continues until the pressure is removed.

The structure W is molded and hardened in the above conditions, and after a sufficient hardening time (L), the cooler 8 is activated,
The structure W is cooled at the maximum cooling rate at which the temperature of each part of the structure W uniformly decreases (M). In this cooling, since the temperature decreases slowly in the thickest portion with the largest heat capacity, the operation of the cooler 8 and the heater elements 13a, 14a is normally controlled in accordance with the rate of temperature decrease in this portion. As a result of this cooling, when the temperature of the structure W reaches a predetermined depressurization temperature (N), the valve 22 is closed and the valve 23 is opened to perform exhaust and depressurize (P). The predetermined pressure relief temperature mentioned above depends on the type of resin of the structure W,
At a temperature determined by the type of the structure W itself,
It is approximately room temperature or several tens of degrees Celsius close to this temperature. After this pressure is removed, the autoclave 1 is opened (Q), and the molded and hardened structure W is taken out and the control is ended.

A heating control cycle and a pressurization control cycle based on the above control are shown in FIGS. 7 and 8, respectively.
Note that in these figures, alphanumeric symbols indicate the symbols in the flowchart shown in FIG. 3 above.

In the conventional method, the molded product was heated only by the temperature of the gas inside the can, but in the device of the present invention described above,
The temperature of each part of the molded product is detected and the temperature cycle of each part of the molded product is precisely controlled using a microcomputer and multi-heater system, resulting in the following effects.

In other words, throughout the entire curing cycle, from raising the temperature of the molded product through the process of maintaining a predetermined curing temperature to cooling and depressurizing, the temperature of each part of the molded product is controlled uniformly, resulting in uniform flow and curing reaction of the resin. Therefore, the resin content of the structure becomes uniform, and therefore the strength properties become uniform.

In addition, since the temperature distribution of the entire structure is uniform until it returns to room temperature, the thermal expansion and thermal contraction become uniform, so the molding distortion is only a slight shrinkage distortion due to curing contraction of the resin. It is possible to prevent mold cracks from occurring.

Furthermore, in the conventional method, as shown by the broken line in Figure 9, due to the heat capacity of the molded product, the temperature increase rate decreases as the temperature approaches a predetermined curing temperature (curing temperature cycle curve, flat top). As a result, the “loss time due to temperature rise delay” shown by α in the figure
However, with this apparatus, each part of the molded product can be made to match a predetermined curing temperature cycle curve, so such lost time in the molding process can be eliminated. In addition, this function allows the temperature of the molded product to match the temperature inside the can, so the temperature increase rate itself can be increased, making it possible to further save molding time.

Furthermore, the device of the present invention has a function of precisely controlling the molding temperature cycle and pressure cycle by electrically detecting the properties of the resin of the molded product, in addition to the function of controlling the multi-heater etc. using a microcomputer. Therefore, by performing this control,
In the resin flow process before gelation, heating and temperature rise can be suppressed and the pressure applied can be controlled to ensure defoaming and removal of gas components within the structure to be molded. Therefore, it is possible to remove voids included when the molding materials are laminated, blisters caused by volatile components generated during the curing reaction, bubble components remaining between the resin and the fibers, and the like. Therefore, the strength properties are uniformly distributed at the highest value, and a molded product without defects can be produced. Furthermore, since the heating and pressurizing conditions can be precisely controlled in accordance with the physical state of the resin, an optimum molding and curing cycle can be provided for each resin. This allows molding to be carried out in response to variations in the type of resin and the quality of the molding material, and the best molding quality can always be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a molding and curing device for resin-based composite materials according to an embodiment of the present invention, FIG. 2 is a plan view showing the arrangement of heater elements of the device in FIG. 1, and FIG. Flow chart for explaining the operation of the device shown in FIG. 1, FIG. 4 is a plan view showing the arrangement of the resin property detector in the device shown in FIG. 1, and FIG. FIG. 6 is a diagram showing an example of a change in the resin property potential signal output by the resin property detector when the resin viscosity changes as shown in FIG. 6, and FIG. 8 is a diagram showing a heating control cycle, FIG. 8 is a diagram showing a pressurization control cycle, and FIG. 9 is a diagram showing a pressurization control cycle.
The figure is a diagram showing some of the effects of the present invention. W... Resin-based composite material structure, 1... Molding hardening device, 2... Molding jig, 3... Vacuum bag, 12...
...Heating device, 13, 14...Multi filter, 1
3a, 14a... Heater element, 16... Control device, 40... Resin property detector.

Claims (1)

[Claims] 1. In an apparatus for molding and curing a resin composite structure in which the resin composite structure is molded under pressure and heat using a bag in an autoclave, a large number of heaters are used to independently heat each part of the structure. A heating means comprising an element, a temperature control means for controlling the heating means, a pressurizing means for pressurizing the structure by relatively adjusting the pressure in the autoclave and the pressure in the bag, and controlling the pressurizing means. pressure control means for detecting temperatures at a plurality of predetermined locations of the structure and generating electrical signals indicative of the detected temperatures; temperature detection means for detecting the pressure within the autoclave and the pressure within the bag; A pressure detection means that generates an electric signal indicating the detected pressure, detects resin properties such as initial fluidization time and gelation start time of the resin at a plurality of predetermined locations of the structure, and generates an electric signal indicating the resin property. The temperature control means receives generated electric signals from the resin property detection means, the temperature detection means, the pressure detection means, and the resin property detection means, and heats and pressurizes the structure according to predetermined conditions. Molding of a resin-based composite material structure comprising a cycle adjustment means for controlling the pressure control means and the temperature control means so as to equalize the temperature of each part of the structure at least during heating and cooling. Curing equipment.