JP2007007910A - Rtm (resin transfer molding) method and resin injection device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance molding quality by controlling the injection amount per unit time of the resin injected in a mold to stabilize the flow of the resin in the mold. <P>SOLUTION: The resin is injected and cured through two stages of injection processes comprising: a pressure raising injection process for arranging a preform, which is formed by winding fibers around the periphery of a core comprising an elastomer, in the mold and raising the injection pressure of the resin with the elapse of time; and a dwelling injection process for injecting the resin so that the injection pressure of the resin becomes constant during a period when it reaches the preliminarily inputted injection amount of the resin after the maximum injection pressure of the resin arrives. At the time of 0≤t≤T<SB>gel</SB>/12, formula (1): [P<SB>lim</SB>/ä(1/3)*T<SB>gel</SB>}]*t≤P(t)≤ä0.9*P<SB>lim</SB>/(T<SB>gel</SB>/12)}*t, and, at the time of T<SB>gel</SB>/12≤t≤T<SB>gel</SB>/3, formula (2): [P<SB>lim</SB>/ä(1/3)*T<SB>gel</SB>}]*t≤P(t)≤0.9*P<SB>lim</SB>+[ä0.01*P<SB>lim</SB>/(T<SB>gel</SB>/4)}]*(t-T<SB>gel</SB>/12). Herein, P(t) is the pressure in a cavity after the elapse of a time (t), P<SB>lim</SB>is the allowable pressure of the core and T<SB>gel</SB>is the gelling time of the resin at a molding temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and a resin injection device for RTM molding using a preform in which reinforcing fibers are wound around the core of an elastic body.

As a resin injection method of RTM, a method of sucking up a resin by evacuating the mold as shown in FIG. 1 or a method of pushing in a resin by air pressure as shown in FIG. 2 is used. On the other hand, in the case of a resin that promotes curing by mixing two or more liquids, it is common to press the respective resins as shown in FIG. However, in these methods, since the mechanism is simple, it is possible to individually control the amount of resin to be injected into the mold or to control the maximum resin injection pressure. It was difficult to inject the resin while controlling everything in a complex and interlocking manner. (For example, Patent Document 1) Further, in the case of a reinforced plastic made of fiber or the like for the purpose of weight reduction represented by FRP (CFRP), a lightweight core in the thickness direction in which a load is applied in order to ensure lightweight and high rigidity. Although the method of increasing the moment of inertia of the cross section by using the squeezing method, the lightweight core generally has a drawback that it is compressed at the time of high-pressure resin injection because of its low elastic modulus. In molding using a lightweight core, the resin injection pressure near the entrance where the resin is injected becomes the highest, so when aiming to improve productivity by speeding up the molding cycle, Since it is difficult to take measures such as molding in anticipation of the compression allowance and requires advanced know-how, the design of the mold and the setting of molding conditions required trial and error. Depending on the variation and the fluctuation of the resin pressure in the mold, there are many cases where the core shrinks more than expected and the molding quality is deteriorated, which leads to a decrease in the molding yield. In order to avoid such a case, the resin injection pressure is lowered and the compression amount is set to be small, so that the injection amount per unit time is low, so the molding cycle must be long, There was a problem that the good productivity that is the original feature of the RTM molding method cannot be enjoyed.
Japanese Patent Laid-Open No. 61-5909 ((P6) Right 30-40 lines)

  Accordingly, an object of the present invention is to stabilize the flow of the resin in the mold and improve the molding quality by controlling the amount of resin injected into the mold per short time. In the conventional resin injection method, for example, in the case of the equipment shown in FIG. 2, if the injection time of the resin into the mold is to be shortened, it can be realized by setting the air pressure high, but the pressure in the mold is naturally the air pressure. Pressurized equally. This makes it necessary to increase the capacity of the lifting device of the mold, or when a lightweight core (for example, a foam material) is used, it causes a volume change due to compression of the lightweight core and eventually breaks down. Therefore, by controlling the amount of resin injected into the mold for a short time, the molding cycle time is shortened and the maximum injection pressure is suppressed (coexistence of core breakage and molding quality). At the same time, we will provide equipment and method that can achieve the stable molding process.

To achieve the above object, the present invention adopts the following configuration. That is,
(1) A preform in which fibers are wound around the core of an elastic body is placed in a molding die, and a pressure injection step for increasing the resin injection pressure with time, and after reaching the maximum resin injection pressure, are input in advance In the RTM molding in which the resin is injected and cured through a two-stage injection process of a pressure-holding injection process in which the resin is injected so that the injection pressure is constant until the injection amount of the resin is reached. An RTM molding method characterized by detecting the pressure and continuously controlling the amount of resin delivered or the pressure per unit time in the pressurizing injection step so as to satisfy the following formula.

When 0 ≦ t ≦ T _gel / 12
[P _lim / {(1/3) * T _gel }] * t ≦ P (t) ≦ {0.9 * P _lim / (T _gel / 12)} * t (1)
When T _gel / 12 <t ≦ T _gel / 3
[P _lim / {(1/3) * T _gel }] * t ≦ P (t) ≦ 0.9 * P _lim + [{0.1 * P _lim / (T _gel / 4)}] * (t−T _gel / 12) (2)
Where
P (t): pressure in the cavity after the elapse of time t P _lim : allowable pressure of the core T _gel : gelation time of the resin at the molding temperature (2) In the pressure-holding injection step, the pressure in the cavity is medium The amount of resin delivered or the pressure per unit time is continuously controlled so that the allowable pressure of the child is in the range of 0.80 to 1.0 times, and the integrated value of the amount of resin delivered from the start of resin injection However, when the volume of the cavity becomes 1.2 to 3 times, the RTM molding method according to (1), wherein the liquid feeding is stopped.

  (3) A resin injection device that is applied to RTM molding in which a preform in which fibers are wound around the core of an elastic body is placed in a mold, and the resin is injected and cured, and means for detecting the resin injection pressure; Means for detecting elapsed time from start of resin injection, means for detecting resin injection amount, means for storing pressure / time / injection amount, and data obtained by the detection means and pre-registered in the storage means A means (program) that compares the conditions calculated by specific calculation formulas from the measured data, sets the resin feed volume or pressure per unit time, and continuously controls the resin feed pump based on this set value A resin injecting device comprising:

  According to the present invention, in a resin injection apparatus that performs RTM molding using a preform in which fibers are wound around the core of an elastic body, a reduction in molding cycle time and high quality, which has been difficult with a conventional resin injection apparatus, are achieved.・ High yield can be achieved at the same time.

  The molded body in the present invention is intended for a fiber reinforced resin (hereinafter abbreviated as FRP) structure in which a preform in which fibers are wound around an elastic core is used as a reinforcing fiber. FRP refers to a resin reinforced with reinforcing fibers. Examples of reinforcing fibers include inorganic fibers such as carbon fibers and glass fibers, or reinforcing fibers made of organic fibers such as Kevlar fibers, polyethylene fibers, and polyamide fibers. Can be mentioned. Examples of the form of the reinforcing fiber include a woven fabric of reinforcing fiber that is not impregnated with resin, a mat, a knit material, and a combination of these with an insert part. Examples of the FRP matrix resin include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, and phenol resins, and further polyamide resins, polyolefin resins, dicyclopentadiene resins, polyurethane resins, and the like. These thermoplastic resins can also be used. In addition, the core is not particularly limited as long as it is an elastic body. Foam materials such as urethane resin, acrylic resin, polymethacrylimide resin, and phenol resin, wood core agents such as balsa, polypropylene, polyethylene, fluorine-based materials And a hollow body in which air pressure is applied to the inside of the thin molded product.

  Hereinafter, a configuration of an RTM (Resin Transfer Molding) molding apparatus according to the present invention and a manufacturing method using the same will be described with reference to the drawings.

  FIG. 4 is a diagram showing an example of the apparatus of the present invention. In this figure, in the left and right resin tanks 1, the epoxy resin main agent and the curing agent are kept at a temperature exceeding room temperature, and at the same time, dissolved gas is removed as much as possible while maintaining a vacuum state. The syringe pump 15 is a pump for injecting each resin into a mold. Here, although a syringe pump is employed this time, a pump with high quantitativeness such as a gear pump can be preferably used. The hydraulic cylinder 16 is connected to the syringe pump 15 and is a drive source of the syringe pump 15. The resin pressurized and fed by the syringe pump 15 is mixed by the mixer 21.

  The resin mixed by the mixer 21 is injected into the mold through the resin injection pipe 3. After the resin injected into the mold is impregnated into the reinforcing fiber base in the mold cavity, the surplus is guided to the resin discharge tank 7.

  Further, the apparatus has the following means in order to control the resin injection pressure over time as will be described later. That is, as the detection means, means for detecting the resin injection pressure, means for detecting the elapsed time from the start of resin injection, means for detecting the resin injection amount, pressure / basic data for obtaining the conditions to be controlled Means for storing information about time and injection amount, and comparing the condition obtained by a specific calculation formula from the data obtained by the detection means and the data registered in advance in the storage means, It is necessary to set a liquid amount or a pressure and to have means (program) for continuously controlling the resin liquid feed pump based on the set value. By combining these means, the resin injection pressure, which will be described later, is controlled over time, and a fiber reinforced resin using a preform in which fibers are wound around the core of an elastic body as a reinforcing fiber is efficiently obtained by the RTM molding method. It becomes possible.

  In the resin injection process performed using the above apparatus, the process includes a pressure injection process for increasing the resin injection pressure over time and a pressure holding injection process for injecting resin so that the pressure after reaching the maximum resin pressure is substantially constant. It is necessary to compose from two stages. In the boost injection process, it is necessary to control the resin pressure P so as to satisfy the relationship of the expressions (1) and (2) with respect to the time t.

When 0 ≦ t ≦ T _gel / 12
[P _lim / {(1/3) * T _gel }] * t ≦ P (t) ≦ {0.9 * P _lim / (T _gel / 12)} * t (1)
When T _gel / 12 <t ≦ T _gel / 3
[P _lim / {(1/3) * T _gel }] * t ≦ P (t) ≦ 0.9 * P _lim + [{0.1 * P _lim / (T _gel / 4)}] * (t―T _gel / 12) (2)
Each symbol in the formula represents the following (measurement method and the like will be described later).

P (t): pressure in cavity after time t P _lim : allowable pressure of core T _gel : gelation time of resin at molding temperature Resin pressure at time t is [P _lim / {(1/3) If below * T _gel }] * t, the resin injection rate will slow down and efficient molding will not be possible, or sufficient time will not be allowed in the pressure-holding injection process, and resin gelation will begin. In addition, there is a problem that a good quality product cannot be obtained due to bubbles remaining in the molded product.

When the time t is 0 ≦ t ≦ T _gel / 12, the resin pressure is {0.9 * P _lim / (T _gel / 12)} * t, and the time t is T _gel / 12 <t ≦ T _gel / 3 When the resin pressure exceeds 0.9 * P _lim + [{0.1 * P _lim / (T _gel / 4)}] * (t-T _gel / 12), the flow rate of the resin becomes too fast and the direction of the reinforcing fiber Problems such as disturbing the pressure, overshooting the pressure exceeding the control range, and crushing the core.

Equations (1) and (2) are based on the resin gelation time at the resin injection temperature, and the resin is injected until it reaches the maximum resin injection pressure at the time of resin injection until 1/3 of the gelation time. It shows that the pressure increase is completed. This is because it is necessary to allow a sufficient pressure holding injection time before the resin gelation begins. Here, the maximum resin injection pressure at the time of RTM molding of an FRP having an elastic core is limited by the allowable pressure of the core, and is therefore set based on the allowable pressure P _{lim of the} core.

  As a means for detecting the pressure P (t) in the cavity, a method of attaching a pressure sensor in the vicinity of the mold in the resin inflow path is generally used. In reality, the pressure in the cavity is not constant because there is a pressure gradient, but the maximum pressure can be detected by attaching a pressure sensor in the vicinity of the mold in the resin inflow path, representing the pressure in the cavity. There is virtually no problem in using it as a numerical value. If the pressure at the mold outlet is also measured in advance, a rough pressure distribution in the cavity can be assumed.

Here, as a method for measuring the gel time T _gel of the resin at the molding temperature, a general dynamic viscoelasticity measuring device (rotary viscometer) can be applied and measured. As measurement conditions, a parallel plate with a radius of 20 mm was used, the distance between the parallel plates was set to 0.5 mm, the complex viscosity η * was measured at a temperature of 80 ° C. and a frequency of 0.5 Hz, and the time for a sudden increase in viscosity to occur. The gelation time is determined as T _gel .

  Also, in the pressure holding injection process, the amount of resin delivered or the pressure per unit time is continuously controlled so that the pressure in the cavity is in the range of 0.80 to 1.0 times the allowable pressure of the core. It is preferable to do. This is because by maintaining the pressure around the maximum resin injection pressure, the resin injection can be completed as soon as possible before gelation. In this step, when the integrated value of the resin liquid supply amount from the start of resin injection reaches the resin liquid supply amount obtained by multiplying the cavity volume by a certain coefficient, the liquid supply is stopped. This is because if the predetermined coefficient is obtained in advance through a pre-molding experiment or the like, it is possible to efficiently determine when the injection is completed, so that waste of time, excess resin, and the like can be prevented. The coefficient is influenced by the capacity and shape of the size mold cavity of the molded product, but is preferably set to 1.2 to 3 times the normal mold cavity.

  5 and 6 show the flow of the resin injection system.

  First, the maximum resin injection pressure (Tmax = Plim) determined from the allowable pressure (Plim) of the core and the time (Tmax = Tgel / 3) required for the pressure injection process obtained from the gel time (Tgel) of the resin are input. To do. Further, in order to determine the end of the pressure holding injection process, the maximum value of the resin flow rate obtained by multiplying the volume of the mold cavity by a certain coefficient is inputted (the certain coefficient is obtained in advance through a preliminary molding experiment or the like. ). The specific control amount of each input information varies depending on the resin injection system (the size and shape of the molding mold cavity, the viscosity of the applied resin and the curing reactivity). A specific control amount will be shown based on this device.

The resin injection device in FIG. 4 specifically uses a syringe pump 15. For this reason, when the input information is replaced with a controlled variable,
Maximum resin injection pressure: The upper limit of the pressure indicated by the pressure gauge 18 which is a resin injection pressure detecting means. Normally, the pressure is set slightly lower than the allowable pressure of the core (the pressure at which the core breaks or causes deformation that may cause problems when using the product). Furthermore, it is preferable to set in a range of 0.8 to 1.0 times the allowable pressure of the core in consideration of variations in molding.

Resin gelation time: The time at which the resin gelation begins at the molding temperature. Check the experiment and resin data in advance (or enter the time calculated from the resin gelation time directly as the completion time of the pressure injection process. May be)
Resin injection amount: The number of repeated strokes of the syringe pump 15 is controlled. As a specific value, in consideration of the amount of resin discarded together with air bubbles so as not to leave air bubbles in the product, an amount 1.2 to 3 times the volume of the cavity filled with the resin is calculated, This volume can be determined by dividing by the volume of the syringe pump. At this time, if the set amount of the resin discarded together with the bubbles is small, bubbles are likely to remain in the product, and if the set amount of the resin discarded is too large, the resin is wasted and the cost is increased.

  According to the flow of FIG. 6, resin injection is performed through the following steps.

  Pressure is applied to the cylinder 16 by the resin injection start 202. This pressure is calculated from the maximum resin injection pressure and the completion time of the pressurization injection process, but since the molding cycle is shortened at the start, the pressure adjustable regulator that can be controlled by an external signal so as to be the maximum pressure of the pressure source 14 A control signal is transmitted to 17b.

  The resin injection valve 4 is opened and the resin is injected into the mold. At this time, it is also possible to obtain a molded product with fewer bubbles by taking measures such as bringing the inside of the mold into a vacuum state in advance.

  In the initial stage of injecting the resin, the resin discharge valve 6 is closed and the mold is filled with the resin. At this time, an increase in the resin injection pressure can be confirmed with the pressure gauge 18 in accordance with the resin filling amount at that time (see FIG. 5). From this detection information, the control unit 20 determines and adjusts whether or not the elapsed time conforms to the range defined by the equations (1) and (2) 207 and controls the pressure adjustment regulator 17b to provide a control signal. Send. Here, there is no problem even if the control method is a more detailed function as long as it is within the range defined by the equations (1) and (2).

  When the value of the pressure gauge 18 as the resin injection pressure detecting means reaches a predetermined resin injection pressure input value that is separately instructed, the discharge valve 6 is opened, and the compressed air in the mold is discharged. Thereafter, the discharge valve 6 is repeatedly opened and closed at a preset interval.

  By performing the above-described operation, the bubbles in the mold are discharged.

  Here, the control unit constantly monitors whether the determination (maximum pressure) 204 has been reached. If the value of the pressure gauge 18 exceeds the maximum injection pressure, the pressure adjusting regulator 17b is controlled to control the cylinder 16. Reduce pressure. Here, as another method, a method of suppressing an increase in pressure by opening the discharge valve 6 is also effective.

  If the above-described operation is continued and the target is satisfied in the judgment (injection amount) 206, the resin injection is terminated at that point, the discharge valve 6 and the injection valve 4 are closed, and the process waits while the resin is cured.

Next, a more specific embodiment will be described with reference to FIG.

  Here, the molded body forms a horizontal wing of a rear spoiler of an automobile member. The structure of the horizontal blade is a structure in which a urethane foam core 30 is used as a core, and a carbon fiber cloth 31 is wound around the core. By winding a cloth around the urethane foam core 30, it can be composed of continuous reinforcing fibers. It is also possible to wind the fiber in the manner of a so-called filament winding. The physical properties of the urethane foam used here are 80 ° C. (molding temperature), and 2 MPa is compressed to 0.3 MPa, and 0.3 MPa is set as the maximum resin injection pressure (allowable pressure of the core).

  A preform 32 in which a carbon fiber cloth 31 is wound around a urethane foam core 30 is placed on a molding die (lower) 9b.

  The molding die (upper) 9a is lowered and overlapped with the molding die (lower) 9b to close the die.

  Examples of the material of the mold include FRP, casting, structural carbon steel, aluminum alloy, zinc alloy, nickel electroforming, and copper electroforming. Structural carbon steel is preferred in terms of mold rigidity, heat resistance, and workability.

  Next, the details of the resin injection will be described.

The mold (upper) 9a and the mold (lower) 9b were provided with resin injection pipes 3a connected to a plurality of resin injection ports (not shown) and resin discharge pipes 3b connected to discharge ports (not shown).
A resin injection part 100 is connected to the resin injection pipe 3a. The resin injection part 100 stores the main agent / curing agent in the resin tank 1 (main agent tank, curing agent tank), respectively, and each tank has a mechanism capable of heating and vacuum degassing. As the main resin, Epicoat 828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy resin) was used as the main agent, and as the curing agent, a liquid epoxy resin obtained by mixing TR-C35H (imidazole derivative) of Toray Blend was used. In the resin injection device 100, the main agent and the curing agent were heated in advance at 40 ° C. while being stirred, lowered to a predetermined viscosity, and degassed by the vacuum pump 8.

  At the time of resin injection, pressure is injected from each tank by the syringe pump 15. For pressurization of the resin, a syringe pump is used, and it is preferable for a resin that is cured by two-component mixing to ensure quantitativeness by simultaneously extruding the syringe. It is mixed by the mixer 21 and reaches the resin injection pipe 3.

  The resin discharge pipe 3 b is connected to the resin discharge tank 7 in order to prevent the resin from flowing into the vacuum pump 8.

  A resin injection valve 4 and a resin discharge valve 6 are installed to control the opening and closing of the resin injection pipe 3a and the resin discharge pipe 3b at the time of resin injection. The resin injection valve 4 and the resin discharge valve 6 use electromagnetic valves or air operation valves, for example, valve opening information that changes the diameter of the flow path (such as adjusting the opening of a ball valve). It is also preferable to perform opening and closing with higher accuracy by connecting a storage device to which is input.

  For the material of the resin injection pipe 3a, it is necessary to ensure sufficient flow rate and compatibility with the resin (temperature, solvent resistance, pressure resistance). A tube with a diameter of 5 to 30 mm is used. A pressure resistance of 1.0 MPa or more is required to withstand the injection pressure of the resin, and a heat resistance of 100 ° C. or more is required to withstand the temperature when the resin is cured, and the thickness is 3 mm. Use a "Teflon" tube to the extent. In addition to “Teflon (registered trademark)”, the material may be polyethylene, steel, or aluminum which is cheaper than “Teflon (registered trademark)”.

  Similarly, the material of the resin discharge pipe 3b needs to take into consideration a sufficient flow rate and compatibility with the resin (temperature, solvent resistance, pressure resistance), but may be basically the same as that of the resin injection pipe 3a.

  In order to keep the inside of the mold sealed, a sealing material is arranged on the outer periphery of the mold. Ideally, by closing the mold (upper) 9a, the interior of the mold is not communicated with other than the resin flow path. However, substantially complete sealing is difficult. For example, the pressure of the pressure gauge 18 is monitored with the resin injection valve 4 disposed in the resin injection pipe 3a closed. If it was in a state where 0.01 MPa could be maintained for 2 seconds, it was determined that there was no problem in molding and the sealed state was confirmed.

  Next, the resin injection valve 4 is opened, and the resin is injected under pressure from the resin injection pipe 3a. Here, the in-mold pressure is displayed on the pressure gauge 18 in FIG.

  However, since the air in the mixer 21 and the air in the hose entered at the initial stage of resin injection, they were discarded from the branch path (not shown) without flowing into the mold. The injection pressure of the resin can be controlled in the range of 0.1 to 1 MPa in this apparatus. When the resin impregnates the base material in the mold and reaches the resin discharge pipe 3b, the resin discharge valve 6 is closed. Almost simultaneously, the resin injection valve 4 is also closed and the injection is completed. The mold is heated by the hot water source 13, thereby curing the resin.

Furthermore, in the RTM molding method according to the present invention, the pressure of the cylinder 16 connected to the synringe pump 15 is adjusted by information from the control unit 104 while the resin is being injected into the molding die. Adjustment here refers to information before injecting resin,
Resin maximum pressure: Upper limit of pressure indicated by pressure gauge 18
Allowable pressure of urethane foam core.

                    Regarding the physical properties of the urethane foam used here, the allowable pressure at 80 ° C. (molding temperature) is set to 0.3 MPa.

Completion time of boost injection process
: Since the gelation time of the resin was about 3 minutes, 60 seconds was set.

                Here, the gel time of the resin composition was measured using a rotational viscometer. As the rotational viscometer, a viscoelasticity measuring device ARES manufactured by Rheometric Scientific F.E. A parallel plate having a radius of 20 mm was used, the distance between the parallel plates was set to 0.5 mm, the complex viscosity η * was measured at a temperature of 80 ° C. and a frequency of 0.5 Hz, and the time when the sudden viscosity increase started was defined as the gel time.

    Resin injection amount: Refers to the number of repeated strokes of the syringe pump 15.

The syringe pump used in this example is 250 cc / stroke for the main agent curing agent. Since the amount of waste resin required for the cavity volume of 670 cc is 50%, the total required injection amount of 1000 cc is 250 cc. Divide and enter 4 strokes.
Enter the three types.

  Pressure is applied to the cylinder 16 by starting resin injection. Since this pressure shortens the molding cycle at the start time, a control signal is transmitted to the pressure adjusting regulator 17b so that the maximum pressure of the pressure source 14 is 1 MPa.

  Next, the resin injection valve 4 is opened and the resin is injected into the mold. At this time, it is also possible to obtain a molded product with fewer bubbles by taking measures such as bringing the inside of the mold into a vacuum state in advance.

  In the initial stage of injecting the resin, the resin discharge valve 6 is closed and the mold is filled with the resin. At this time, an increase in the resin injection pressure can be confirmed with the pressure gauge 18 according to the resin filling amount at that time (see FIG. 5). From this detection information, the control unit 20 determines whether or not 207 is suitable for the time required for the boost injection process of 60 seconds, and transmits a control signal to the pressure regulating regulator 17b so as to set an appropriate pressure. To do. In the example, since the maximum pressure on the facility of 1 MPa was initially set, the pressure adjustment control was performed immediately after the start.

  As another object, in order to promote the removal of bubbles in the mold and to obtain a higher quality molding quality, the value of the pressure gauge 18 which is a resin injection pressure detecting means is added to the resin injection pressure input value specified separately. When the pressure reached, the discharge valve 6 was opened, and the compressed air in the mold was discharged. The gas remaining in the mold suddenly expanded / contracted, and a rapid resin flow was generated along with the change in the volume of the gas, which remained between the reinforced substrate and the mold surface. The gas can no longer stay due to this rapid resin flow and is discharged to the resin discharge pipe 3b. Such complicated control of the resin discharge valve 6 is performed, and even when the pressure of the resin temporarily decreases, a signal is sent to the pressure regulating regulator so that the resin pressure immediately returns to the range to be controlled. Needless to say. The resin discharge valve 6 was implemented within 1 second from the closed state to the open state and from the closed state to the open state during the resin injection process.

  Thereafter, the control unit constantly monitors whether the judgment (maximum pressure) has reached 0.3 MPa, and further controls the pressure-regulating regulator 17b when the value of the pressure gauge 18 reaches the maximum injection pressure. The pressure in the cylinder 16 is reduced.

When the above operation is continued and the determination (injection amount) satisfies the number of syringe strokes 4 times, at the start of the fifth time, the discharge valve 6 is closed and then the injection valve 4 is closed, and the resin injection is finished and the resin is finished. It was decided to wait while it hardened.
Proceed with the process.

  This is left for 30 minutes to cure. As a result, good molded product quality can be obtained at the same time without impairing the shape of the urethane foam core.

  As an operation for promoting impregnation of the resin into the reinforcing fiber base and removing bubbles, the resin injection valve 4 and the resin discharge valve 6 were opened and closed by binary control, and the opening and closing operation was manually performed using a vise grip.

  Once cured, the mold (top) is raised and the mold is opened. The RTM molding is removed from the molding die (lower) 9b (so-called demolding).

  As another embodiment, a ball valve or the like is used as the discharge valve 6, and the valve opening degree can be accurately determined by controlling the rotation angle of the ball with a servo motor. In addition, by previously registering the rotation angle and timing in the computer, it is possible to automatically control the valve, which can be easily realized without increasing the number of workers.

  The present invention can be applied to a resin supply apparatus and a supply method for RTM molding.

An example of the conventional resin injection apparatus. An example of the conventional resin injection apparatus. An example of the conventional resin injection apparatus. An example of the resin injection device of the present invention Transition of pressure in the mold by the resin injection device of the present invention. Flow chart of the present invention Preform used in the present invention

Explanation of symbols

1: Resin tank 2: Resin 3: Resin injection pipe 4: Resin injection valve 5: Resin valve controller 6: Resin discharge valve 7: Resin discharge tank 8: Vacuum pump 9a: Mold (upper)
9b: Mold (bottom)
10: Mold lifting shaft 11: Hydraulic cylinder 12: Check valve 13: Hot water source 14: Pressurization source 15: Syringe pump 16: Hydraulic cylinder for syringe pump 17a: Regulator 17b: Pressure adjustment regulator 18 by external signal Total 19: Input unit 20: Control unit 21: Mixer 30: Urethane foam core 31: Carbon fiber cloth 32: Preform 100: Resin injection unit 101: Mold raising / lowering unit 102: Resin discharging unit 103: Molding unit 104: Control unit 201: Input of control information 202: Resin injection start 203: Pump drive 204: Judgment (maximum pressure)
205: Pressure control 206: Determination (resin amount)
207: Resin injection adjustment 208: End

Claims (3)

A preform with fibers wrapped around the core of the elastic body is placed in the mold, and a pressure injection process for increasing the resin injection pressure over time, and injection of resin that has been input in advance after reaching the maximum resin injection pressure RTM molding that injects and cures the resin through a two-stage injection process in which the resin is injected so that the injection pressure remains constant until the amount reaches a certain level, and detects the pressure in the cavity. The RTM molding method is characterized by continuously controlling the amount or pressure of resin delivered per unit time in the pressurizing injection process so as to satisfy the following formula.
When 0 ≦ t ≦ T _gel / 12
[P _lim / {(1/3) * T _gel }] * t ≦ P (t) ≦ {0.9 * P _lim / (T _gel / 12)} * t (1)
When T _gel / 12 <t ≦ T _gel / 3
[P _lim / {(1/3) * T _gel }] * t ≦ P (t) ≦ 0.9 * P _lim + [{0.1 * P _lim / (T _gel / 4)}] * (t−T _gel / 12) (2)
Where
P (t): pressure in the cavity after the elapse of time t _Plim : allowable core pressure _Tgel : resin gelation time at molding temperature In the pressure-holding injection step, the liquid feed amount or pressure per unit time is continuously controlled so that the pressure in the cavity is in the range of 0.80 to 1.0 times the allowable pressure of the core, The RTM molding method according to claim 1, wherein the liquid feeding is stopped when the integrated value of the resin liquid feeding amount from the start of resin injection becomes 1.2 to 3 times the cavity volume. A resin injection device applied to an RTM molding in which a preform in which fibers are wound around the core of an elastic body is placed in a mold, and the resin is injected and cured, and means for detecting the resin injection pressure, resin injection From the means for detecting the elapsed time from the start, the means for detecting the resin injection amount, the means for storing the pressure / time / injection amount, the data obtained by the detection means and the data registered in the storage means in advance Comparing the conditions calculated with a specific formula, set the resin feed volume or pressure per unit time, and have means (program) to continuously control the resin feed pump based on this set value A resin injection device characterized by the above.

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