JP2021020375A - Molding apparatus and molding method - Google Patents

Abstract

To provide an apparatus and a method that shorten a cycle time when forming CFRTP.SOLUTION: A molding apparatus for molding a material to be molded of CFRTP comprises a press device 100 having a frame 110, a screw 140, a slide 120, and a bolster 130, a cushion device 400, an upper mold 200 attached to the slide 120, and a lower mold 300 attached to the bolster 130 via the cushion device 400. The press device 100 is configured such that when the frame 110 is extended and an upward load is applied to the slide 120, the screw 140 and the slide 120 are in a stick state. The cushion device 400 is configured to apply a holding pressure equal to or lower than a molding pressure to a sandwiched material by accumulating the molding pressure when the heated material to be molded is sandwiched between the low-temperature upper mold 200 and lower mold 300.SELECTED DRAWING: Figure 2

Description

The present invention relates to a technique for molding a fiber reinforced resin, and more particularly to a technique for molding a fiber reinforced resin by press molding.

In recent years, carbon fiber reinforced resin (CFRP) has been attracting attention as a lightweight and high-strength material. Among them, carbon fiber reinforced thermoplastic resin (CFRTP) using a thermoplastic resin as a matrix material has excellent mechanical properties, and it is necessary to heat it for a long time in a state where molding is completed for curing. However, since it can be molded by a method such as press molding that can shorten the cycle time, it is expected as a material that enables the formation of high-strength members at low cost.

When the CFRTP material is molded, if the temperature of the CFRTP material to be molded is lowered, the fluidity of the matrix material is lowered and the movement of carbon fibers is hindered. Further, if the molded CFRTP material is taken out in a state where the temperature is not sufficiently lowered, the molded CFRTP material is deformed. Therefore, as a method for press-molding the CFRTP material, a heat-and-cool method has been adopted in which molding is performed after heating the mold and the mold is cooled after the molding is completed. However, in the heat and cool method, it is difficult to shorten the cycle time of press molding because it takes time to raise and lower the temperature of the die.

On the other hand, in the case of press molding, if the temperature of the die is lowered (below the melting point of the matrix material) in order to shorten the cycle time, the CFRTP material is cooled in the press molding process, so that the moldability is good. It becomes difficult to keep it. Therefore, development of a technique for suppressing a decrease in temperature of a CFRTP material and maintaining good moldability of the CFRTP material when performing press molding using a low-temperature mold is underway. For example, in Non-Patent Document 1, when press molding is performed using a mold whose temperature is room temperature, the carbon fiber sheet is sandwiched between silicon rubbers to suppress a decrease in the temperature of the carbon fiber sheet, resulting in moldability. Attempts are being made to improve.

Takeshi Yoneyama, 5 outsiders, "Press Processing of Thermoplastic Carbon Fiber Sheets", Plasticity and Processing (Journal of the Japan Society for Plasticity Processing), Japan Society for Plasticity Processing, February 2012, Vol. 53, No. 613, p. 55-59

However, in Non-Patent Document 1, in order to improve the moldability, the carbon fiber sheet is sandwiched between silicon rubbers to suppress the decrease in the temperature of the carbon fiber sheet. Therefore, after the molding is completed, the temperature of the carbon fiber sheet is suppressed. It takes a long time for the amount to decrease sufficiently. Therefore, it is difficult to sufficiently shorten the cycle time by using the technique of Non-Patent Document 1. This problem is not limited to the molding of carbon fiber reinforced resin, but is common to the molding of fiber reinforced resin including glass fiber reinforced resin and the like.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a technique for shortening a cycle time when molding a fiber-reinforced thermoplastic resin.

In order to achieve at least a part of the above object, the present invention can be realized as the following form or application example.

[Application example 1]
A molding device for molding a fiber-reinforced thermoplastic resin material to be molded, which includes a thermoplastic resin matrix material and reinforcing fibers, and is a frame and a screw in which vertical movement with respect to the frame is restricted and a male screw is formed. A slide in which a female screw that meshes with the male screw is formed, and a bolster that is arranged below the slide and fixed to the frame, and the slide is moved up and down by rotating the screw. The configured screw press device, the cushion device attached to the upper side of the bolster, the lower side of the slide and the upper side of the cushion device, respectively, are attached and heated to a temperature higher than the melting point of the matrix material. The cushioning device comprises an upper mold and a lower mold whose temperature is set to be equal to or lower than the melting point of the matrix material, which sandwiches the molded material to be molded and forms the material to be molded. By accumulating the molding pressure applied to the material to be molded when the molding is completed, a holding pressure equal to or lower than the molding pressure is applied to the material to be molded sandwiched between the upper mold and the lower mold. The lead angles of the male screw and the female screw are formed on the screw and the screw when the frame extends in the vertical direction and an upward load is applied to the slide at the end of molding of the material to be molded. A molding device in which the slide is set to be in a stick state.

According to this application example, the lead angles of the male and female threads are set so that the screw and the slide are in a stick state when the frame extends in the vertical direction and an upward load is applied to the slide. , A sufficiently high molding pressure can be applied to the material to be molded immediately after molding sandwiched between the upper mold and the lower mold. Therefore, the shapes of the upper mold and the lower mold can be satisfactorily transferred to the molded material to be molded. Then, since a sufficiently high holding pressure can be applied to the molded material to be molded, the heat transfer coefficient between the upper and lower dies and the material to be molded after molding is increased, and the molded material is said to be molded. Since the material can be cooled quickly, the cycle time at the time of molding can be further shortened. Further, in this application example, when the frame extends in the vertical direction and an upward load is applied to the slide, the screw and the slide are in a stick state, so that two dies are formed when the molding of the material to be molded is completed. Bounce that separates the molds can be suppressed.

[Application example 2]
The molding apparatus according to claim 1, wherein the stick state of the screw and the slide is maintained in a state where the holding pressure is applied to the material to be molded.

According to this application example, even when the holding pressure is applied to the material to be molded, the screw and the slide are in the stick state, so that it is easier to apply the holding pressure to the material to be molded.

[Application example 3]
The molding device according to Application Example 1 or 2, wherein the cushion device is configured so that the holding pressure can be adjusted.

According to this application example, by appropriately adjusting the holding pressure, the impact force applied from the upper mold to the lower mold when the material to be molded is sandwiched between the upper mold and the lower mold can be sufficiently relaxed. Therefore, it is possible to more reliably suppress the occurrence of bounce when the molding of the material to be molded is completed.

[Application example 4]
A molding apparatus according to any one of Application Examples 1 to 3, wherein a liquid chamber is formed, a cylinder portion attached to the bolster, and a working fluid contained in the liquid chamber and contained in the liquid chamber. In the piston portion having a pressure receiving portion that generates an upward load by the pressure of the above, a mold mounting portion provided on the upper side of the pressure receiving portion and to which the lower mold is mounted, and the liquid chamber of the piston portion. It has a connected fluid circuit, and the fluid circuit is configured so that the connection flow path connected to the liquid chamber can be closed while the initial pressure is applied to the working liquid. Molding equipment.

According to this application example, the cushioning device having a simple structure can accumulate the molding pressure and apply the holding pressure to the molded material after molding, so that the molded material is quickly cooled and molded. It becomes easier to suppress the bounce while shortening the cycle time.

[Application example 5]
The molding apparatus according to Application Example 4, wherein the fluid circuit has an accumulator connected to the connection flow path.

According to this application example using an accumulator, it becomes easier to set the holding pressure appropriately.

[Application example 6]
The molding apparatus according to any one of Application Examples 1 to 5, wherein the slide is driven so that the lowering speed in the vicinity of the lower end position of the slide at which molding of the material to be molded is completed is 100 mm / s or more.

According to this application example, it is possible to suppress quality deterioration such as wrinkles and voids in the material to be molded after molding.

[Application 7]
The molding device according to any one of Application Examples 1 to 6, wherein the screw press device is a servo screw press device that drives the rotation of the screw by a servo motor.

According to this application example, since the descending speed of the slide can be appropriately controlled, the quality of the material to be molded after molding can be further improved.

The present invention can be realized in various aspects. For example, it can be realized by a molding device or a molding method for molding a material to be molded of a fiber-reinforced thermoplastic resin, a manufacturing device or a manufacturing method of a molded product of a fiber-reinforced thermoplastic resin using the device or method. ..

The explanatory view which shows the state of molding CFRTP using the molding apparatus as one Embodiment of this invention. Explanatory drawing which shows the structure of the molding apparatus. Explanatory drawing which shows the structure of the cushion device. The explanatory view which shows the operation of the molding apparatus of this embodiment. The graph which shows the result of having confirmed the operation of the molding apparatus of this embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in the following order.
A. Embodiment:
A1. CFRTP molding process:
A2. Molding equipment configuration:
A3. Cushion device configuration:
A4. Molding equipment operation:
A5. Evaluation of molding equipment operation:
B. Modification example:

A. Embodiment:
A1. CFRTP molding process:
FIG. 1 is an explanatory diagram showing a state in which a carbon fiber reinforced thermoplastic resin (CFRTP) is molded using the molding apparatus 10 as an embodiment of the present invention. 1 (a) to 1 (c) show an outline of a molding process of molding a CFRTP prepreg (hereinafter, also simply referred to as “prepreg”) PPG to be molded to obtain a molded prepreg PPF. In FIG. 1, the vertical upper part is drawn so as to be the upper part of the paper surface. Therefore, the vertical direction of the paper surface is the vertical direction, and the horizontal direction of the paper surface is the horizontal direction. Similarly, in the following, unless otherwise specified, the vertical direction and the horizontal direction are expressed as the vertical direction and the horizontal direction of the paper surface. Further, in the following, the vertically upper part and the vertical lower part are also simply referred to as "upper" and "lower".

In the molding process shown in FIG. 1, first, a prepreg PPG to be molded is prepared. The prepreg PPG is a plate-shaped material in which a plurality of CFRTP sheets impregnated with a matrix material are laminated on a carbon fiber woven fabric in which carbon fiber threads, which are reinforcing fibers, are woven. As the matrix material, various thermoplastic resins can be used. Specifically, as the matrix material, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, acrylonitrile butadiene styrene, polymethyl methacrylate, polyetheretherketone, polyurethane, polyamide (nylon) and the like can be used.

As shown in FIG. 1A, the prepared prepreg PPG is carried into the heating device 910. In the heating device 910, the prepreg PPG is heated to a predetermined heating temperature. The heating temperature can be appropriately set as long as it exceeds the melting point of the matrix material, but it is preferably set to a temperature 50 to 70 ° C. higher than the melting point in consideration of a decrease in temperature in the molding process. The heated prepreg PPG is carried out from the heating device 910 and carried into the molding device 10 shown in FIG. 1 (b). The prepreg PPG can be carried into the heating device 910, the prepreg PPG can be carried out from the heating device 910, and can be carried into the molding device 10 by using an automatic transfer device or the like.

As shown in FIG. 1 (b), the molding apparatus 10 includes a press apparatus 100, an upper mold 200 and a lower mold 300 (hereinafter, also collectively referred to as a “die”), and a cushion device 400. .. The press device 100 is a screw press device (servo screw press device) using a servomotor 153, and is fixed to the frame 110, a slide 120 that can move in the vertical direction (vertical direction) with respect to the frame 110, and the frame 110. It has a bolster 130 and a servomotor 153 mounted on the surface.

The upper die 200 is attached to the lower side of the slide 120 of the press device 100, and the cushion device 400 and the lower die 300 are attached to the upper side of the bolster 130 in this order. The prepreg PPG carried into the press device 100 is arranged between the upper die 200 and the lower die 300 as shown in FIG. 1 (b).

After the arrangement of the prepreg PPG, the slide 120 is lowered to a predetermined position (lower end position) by driving the servomotor 153 that controls the raising and lowering of the slide 120. When the slide 120 is lowered to the lower end position, the prepreg (not shown) being molded is sandwiched between the upper mold 200 and the lower mold 300. As a result, as shown in FIG. 1 (c), the prepreg is formed into a shape corresponding to the shapes of the upper mold 200 and the lower mold 300, and a prepreg PPF formed into a desired shape is obtained. In this way, the state in which the prepreg being molded is sandwiched between the upper mold 200 and the lower mold 300 is a state in which the shape of the prepreg is molded into a desired shape, so that the prepreg is molded. Can also be said to be in the finished state.

After lowering the slide 120 to the lower end position, a state in which pressure (holding pressure) is applied to the molded prepreg PPF is maintained until a preset time (holding time) elapses. Since the temperature of the upper mold 200 and the lower mold 300 is set to be equal to or lower than the melting point of the matrix material, the temperature of the prepreg PPF is lowered and the prepreg PPF is cured before the holding time elapses. The prepreg PPF (molded article) molded into a desired shape and cured is taken out from the press device 100 by driving the servomotor 153 to raise the slide 120 after the holding time has elapsed.

The temperature of the mold can be arbitrarily set as long as it is below the melting point of the matrix material, but it is preferably 80 ° C. or lower. By setting the temperature of the mold to 80 ° C or lower, adhesion of the matrix material to the mold is suppressed, so that the molded product can be easily taken out, and cleaning of the mold can be omitted or the frequency of cleaning the mold can be reduced. It can be reduced. Further, if the temperature of the mold is set to 80 ° C. or lower, the holding time can be shortened and the cycle time can be further shortened.

Further, in the present embodiment, in order to suppress deterioration of the quality of the prepreg PPF after molding such as the generation of wrinkles and voids, the slide 120 is lowered at a sufficiently high descending speed (hereinafter, hereinafter, until the slide 120 reaches the vicinity of the lower end position. The descending speed of the slide 120 is simply lowered (also referred to as "descent speed"). Here, the vicinity of the lower end position is a position where the shape of the prepreg during molding is sufficiently close to the shape of the prepreg PPF after molding. Under general prepreg molding conditions, the vicinity of the lower end position is the position where the distance from the lower end position is such that the prepreg PPG before molding comes into contact with the molds 200 and 300 and molding is started (molding start position). It is a position that is 1/5 or less of the distance from the to the lower end position where molding is completed.

The descending speed at the time when the slide 120 reaches the vicinity of the lower end position is preferably 100 mm / s or more. However, since the moldability tends to decrease as the thickness of the prepreg becomes thinner, the descending speed at the time when the slide 120 reaches the vicinity of the lower end position in order to more reliably suppress the deterioration of the quality of the prepreg PPF after molding. Is preferably 300 mm / s or more.

As described above, in the present embodiment, since the lowering speed of the slide 120 is increased until it reaches the vicinity of the lower end position, the slide 120 reaches the lower end position and the prepreg being molded becomes the molds 200 and 300. When sandwiched, a strong molding pressure is applied to the molded prepreg PPF. Further, a strong reaction force that pushes up the slide 120 is applied to the slide 120 in response to the molding pressure applied to the prepreg PPF. When such a strong reaction force is applied to the slide 120, the slide 120 rises immediately after the prepreg is sandwiched between the molds 200 and 300, and a phenomenon (bound) occurs in which the upper mold 200 and the lower mold 300 are separated from each other. There is a risk. Therefore, in the molding apparatus 10 of the present embodiment, the configuration of the press apparatus 100 is changed from the general screw press apparatus as described later, and the cushion apparatus 400 is arranged between the lower mold 300 and the bolster 130. By this, the bounce is suppressed.

In the present embodiment, the descending speed of the slide 120 is increased until it reaches the vicinity of the lower end position, but when the descending speed of the slide 120 in the vicinity of the lower end position is not high (for example, when it is less than 100 mm / s). ), There is a possibility that a bounce will occur. Therefore, the bounce suppressing means adopted in the present embodiment, in which the configuration of the press device 100 is changed and the cushion device 400 is arranged between the lower mold 300 and the bolster 130 as described later, is at the lower end position. It is preferable to apply it even when the descending speed of the slide 120 is not high in the vicinity of. However, the lowering speed of the slide 120 should be sufficiently high until it reaches the vicinity of the lower end position in that it is possible to suppress the deterioration of the quality of the prepreg PPF after molding such as the generation of wrinkles and voids. preferable.

A2. Molding equipment configuration:
FIG. 2 is an explanatory diagram showing the configuration of the molding apparatus 10. In FIG. 2, regarding the press device 100 constituting the molding device 10, the servomotor 153 is not shown, and the appearance from the front is shown on the left side of the central axis indicated by the alternate long and short dash line, and some members thereof are shown on the right side. The partial cross section of the cut is shown. This partial cross section shows a state of being cut along a plane parallel to the front surface through the central axis.

As shown in FIG. 2, the press device 100 includes the frame 110, the slide 120, and the bolster 130 described above, as well as a screw 140, a rotary drive unit 150, a slide guide 160, and a balancer 170.

The frame 110 includes an outer shell plate 111 and an inner shell plate 112 extending in the vertical direction, a top plate 113 arranged on the upper surfaces of the outer shell plate 111 and the inner shell plate 112, a shaft fixing member 114, and a thrust bearing 115. It has a bushing 116. Each of these members 111 to 116 is fixed to each other and constitutes a so-called gate-shaped (bridge-shaped) frame. The inner shell plate 112 is provided with an opening 119 that penetrates in the horizontal direction. Further, a slide guide 160 extending in the vertical direction is fixed to the central axis side of the inner shell plate 112.

The slide 120 has a slide body 121 provided with a hole 129 along the central axis, and a female threaded plate 122 fixed to the slide body 121. The female screw plate 122 is a cylindrical member, and a female screw 128 is formed on the inner surface thereof. As described above, since the slide 120 has the female screw plate 122 on which the female screw 128 is formed, it can be said that the female screw 128 is formed on the slide 120 itself.

The slide body 121 is configured to slide with respect to the slide guide 160 at its end. Therefore, the slide 120 is restricted from rotating around the central axis and can move in the vertical direction. On the other hand, the bolster 130 that does not move in the vertical direction is fixed to the frame 110.

The screw 140 is a member formed of a single bar, and a shaft 141, a large diameter portion 142 having a larger outer diameter than the shaft 141, and a male screw 143 are formed in this order from vertically above. In the press device 100, the shaft 141 is fixed to the thrust bearing 115 of the frame 110, and the upper surface of the large diameter portion 142 is in contact with the bushing 116 of the frame 110. As a result, the screw 140 is restricted from moving in the vertical direction with respect to the frame 110. Further, the male screw 143 provided on the screw 140 is meshed with the female screw 128 provided on the female screw plate 122 of the slide 120.

In the press device 100 used in the present embodiment, the lead angles (hereinafter, also referred to as “screw lead angles”) of the male screw 143 formed on the screw 140 and the female screw 128 provided on the female screw plate 122 are set. , The angle is set smaller than that of a general screw press device (for example, 7 °).

By setting the lead angle of the screw to a sufficiently small angle (for example, 9 ° or less) in this way, most of the vertical load applied to the slide 120 is the male screw 143 formed on the screw 140 and the slide 120 (for example, 9 ° or less). It acts as a normal force that generates a frictional force with the female screw 128 formed on the female screw plate 122). Therefore, the rotation of the screw 140 can be suppressed, that is, the screw 140 and the slide 120 can be in a stick state.

If the lead angle of the screw becomes excessively small, it is necessary to increase the rotation speed of the servomotor 153 (FIG. 1) in order to make the ascending / descending speed of the slide 120 a desired speed. Further, the slide 120 may be difficult to move up and down due to the imbalance between the upward load applied to the slide 120 by the balancer 170 described later and the weight of the slide 120 or the like. Therefore, the lead angle of the screw is preferably 5 ° or more.

The rotation drive unit 150 has a pulley 151 and a toothed belt 152. The shaft 141 of the screw 140 is fitted in the center of the pulley 151. The toothed belt 152 is attached so as to hang the pulley 151 shown in FIG. 2 and the servo motor 153 (FIG. 1). Therefore, by rotating the servomotor 153, the pulley 151 and the screw 140 rotate around the central axis. Then, as the screw 140 rotates, the slide 120 having the female screw 128 meshed with the male screw 143 moves in the vertical direction in accordance with this rotation.

The balancer 170 has a balance cylinder 171 and a cylinder rod 172 extending from the balance cylinder 171 and a connecting arm 173 connecting the cylinder rod 172 and the slide 120 (slide body 121). By applying pressure from below the balance cylinder 171 using compressed air or the like, the cylinder rod 172 and the slide 120 are pushed up in proportion to their weights. By pushing up the cylinder rod 172 and the slide 120 in this way, it becomes easier to control the raising and lowering of the slide 120, and the gap between the male screw 143 and the female screw 128 is suppressed.

The cushion device 400 constituting the molding device 10 has a piston portion 410, a cylinder portion 420, and a pressing ring 430 as mechanical portions, and a hydraulic circuit (not shown). The details will be described later, but in the present embodiment, the cushion device 400 is used, the lead angle of the screw is reduced as described above, and when an upward load is applied to the slide 120, the screw 140 and the slide By making it possible to generate a stick state (stick state) with the 120, the bounce when the slide 120 reaches the lower end position is suppressed.

A3. Cushion device configuration:
FIG. 3 is an explanatory diagram showing the configuration of the cushion device 400. As described above, the cushion device 400 has a piston portion 410, a cylinder portion 420, a pressing ring 430, and a hydraulic circuit 440 as mechanical portions. Note that, in FIG. 3, the configurations of the mechanical units 410, 420, and 430 are schematically shown, and the configurations of the hydraulic circuit 440 are shown in the circuit diagram.

The piston portion 410 is a member having a pressure receiving portion 411 having a large outer diameter and applying hydraulic pressure, and a mold mounting portion 412 formed on the upper side of the pressure receiving portion 411 to which the lower mold 300 (FIG. 2) is mounted.

The cylinder portion 420 is a member that accommodates the pressure receiving portion 411 of the piston portion 410 and has a hole (oil chamber) 429 in which hydraulic oil is stored. The oil chamber 429 formed in the cylinder portion 420 communicates with the connection port 428 connected to the hydraulic circuit 440. Therefore, by adjusting the pressure of the hydraulic oil by the hydraulic circuit 440, the pressure applied to the pressure receiving portion 411 of the piston portion 410, that is, the load transmitted by the mold mounting portion 412 to the lower mold 300 can be adjusted.

The pressing ring 430 is an annular member having an inner diameter smaller than that of the pressure receiving portion 411 of the piston portion 410 and a larger inner diameter than the mold mounting portion 412, and is fixedly attached to the upper side of the cylinder portion 420. By attaching the pressing ring 430 to the cylinder portion 420 in this way, the escape of the piston portion 410 from the cylinder portion 420 is suppressed.

The hydraulic circuit 440 includes an oil tank 441, a bidirectional pump 442, a servomotor 443 that drives the bidirectional pump 442, a solenoid valve 444, and an accumulator 445. As shown in FIG. 3, the bidirectional pump 442 has one port connected to the oil tank 441 and the other port connected to the solenoid valve 444. The solenoid valve 444 switches between an open / closed state between an inlet port connected to the bidirectional pump 442 and an outlet port connected to the accumulator 445 and the connection port 428 of the cylinder portion 420. The accumulator 445 is a diaphragm type gas accumulator, and is connected between the solenoid valve 444 and the cylinder portion 420.

In the example of FIG. 3, a diaphragm type gas accumulator is used as the accumulator 445, but a Prada type or piston type gas accumulator or an accumulator having a gas container provided outside may be used. Is also possible. Further, the solenoid valve 444 shown in the example of FIG. 3 can be replaced with various solenoid valves or pneumatic valves whose opening / closing state can be switched. Further, in the present embodiment, oil (hydraulic oil) is used as the hydraulic fluid used in the cushion device 400, but various liquids such as water can be used as the hydraulic fluid in addition to oil. Is.

A4. Molding equipment operation:
FIG. 4 is an explanatory diagram showing the operation of the molding apparatus 10 of the present embodiment. 4 (a) to 4 (d) show a series of operations of the molding apparatus 10 when molding the prepreg in chronological order. Note that in FIG. 4, the press device 100 (FIG. 2) included in the molding device 10 is not shown. The black arrows drawn in FIG. 4 indicate the direction in which the hydraulic oil flows.

As shown in FIG. 4A, in this embodiment, an initial pressure is applied to the accumulator 445 prior to molding the prepreg PPG. Specifically, the solenoid valve 444 is opened and the bidirectional pump 442 is driven to deliver hydraulic oil from the oil tank 441 toward the solenoid valve 444. As a result, hydraulic oil flows into the accumulator 445, and the pressure of the accumulator 445 rises. Further, the hydraulic oil also flows into the oil chamber 429 of the cylinder portion 420, so that the piston portion 410 is pushed up.

After the pressure of the accumulator 445 rises and reaches a predetermined initial pressure, as shown in FIG. 4B, the bidirectional pump 442 is stopped and the solenoid valve 444 is closed. As a result, the connection flow path connected to the oil chamber 429 (FIG. 3) of the cylinder portion 420, that is, the flow path from the solenoid valve 444 to the connection port 428, is in a closed state in which the inflow and outflow of hydraulic oil is stopped. ..

In this way, when the slide 120 (FIG. 2) is started to descend after the solenoid valve 444 is closed and the connection flow path is closed, the upper die 200 moves toward the lower die 300 located below. To do. In this state, the same pressure as the accumulator 445 (that is, the initial pressure) is applied to the accumulator 445, the oil chamber 429 (FIG. 3), and the hydraulic oil in the connecting flow path. Therefore, the state shown in FIG. 4B can be said to be a state in which an initial pressure is applied to the hydraulic oil.

When the upper mold 200 is further lowered from the state shown in FIG. 4 (b) and the molding of the prepreg is completed, the prepreg PPF is sandwiched between the upper mold 200 and the lower mold 300 as shown in FIG. 4 (c). Is done. At this time, the frame 110 is stretched in the vertical direction by the kinetic energy stored in the rotary drive unit 150, the screw 140, and the slide 120 (see FIG. 2). Further, the kinetic energy is used to extend the frame 110, so that the rotation of the rotation drive unit 150 and the screw 140 is stopped.

When the frame 110 is stretched in the vertical direction, the reaction force is applied to the upper mold 200 and the lower mold 300, and a strong forming pressure is applied to the prepreg PPF. In this way, when the molding of the prepreg is completed, that is, when the pressurization of the prepreg PPF is started, a strong molding pressure is applied to the prepreg PPF, so that the prepreg PPF has the shapes of the molds 200 and 300. Transferred well.

At this time, a large upward load is applied to the slide 120 in response to the strong forming pressure applied to the prepreg PPF. Further, in the present embodiment, since the pitch angle of the screw is reduced, most of the load generates a frictional force between the male screw 143 formed on the screw 140 and the female screw 128 formed on the slide 120. Acts as a normal force to force. When the molding of the prepreg is completed, the rotation of the screw 140 is stopped, so that a strong static frictional force acts between the male screw 143 and the female screw 128, and the screw 140 and the slide 120 are stuck. It becomes. By bringing the screw 140 and the slide 120 into a stick state in this way, the rise of the slide 120 is suppressed, so that the bounce is suppressed.

Further, the molding pressure applied to the prepreg PPF is transmitted to the hydraulic oil stored in the cylinder portion 420 via the lower mold 300 and the piston portion 410 as a load corresponding to the molding pressure. When the molding pressure is transmitted to the hydraulic oil stored in the cylinder portion 420, the pressure of the hydraulic oil stored in the cylinder portion 420 (hereinafter, also referred to as “pressure of the cylinder portion 420”) becomes higher than the pressure of the accumulator 445. It gets higher. Therefore, as shown by an arrow in FIG. 4C, the hydraulic oil stored in the cylinder portion 420 flows into the accumulator 445, and the pressure of the accumulator 445 rises. Since such an increase in the pressure of the accumulator 445 is generated by applying a strong molding pressure to the prepreg PPF, it can be regarded as accumulating the molding pressure.

When the pressure of the accumulator 445 rises due to the inflow of the hydraulic oil and becomes the same pressure as the pressure of the cylinder portion 420, the inflow of the hydraulic oil into the accumulator 445 stops. In this state, the lower mold 300 and the piston portion 410 to which the lower mold 300 is attached move downward as the hydraulic oil flows out. Further, since the same pressure as the pressure of the accumulator 445 is applied to the lower surface of the piston portion 410, the prepreg PPF sandwiched between the upper mold 200 and the lower mold 300 has a holding pressure corresponding to the pressure of the accumulator 445. In addition, an upward load is applied to the slide 120 (FIG. 2) via the upper mold 200 sandwiching the prepreg PPF.

Further, even after the pressures of the accumulator 445 and the cylinder portion 420 become the same from the time when the molding of the prepreg is completed, a sufficiently large load corresponding to the holding pressure is applied upward to the slide 120. carry on. Therefore, the stick state of the screw 140 and the slide 120 is maintained, and the rise of the slide 120 is continuously suppressed, so that the holding pressure can be continuously applied to the prepreg PPF.

The holding pressure applied to the prepreg PPF can be appropriately adjusted as long as it is equal to or lower than the molding pressure, as long as the stick state of the screw 140 and the slide 120 is maintained. The holding pressure can be adjusted, for example, by appropriately adjusting the gas pressure (enclosed gas pressure) to be sealed in the gas chamber of the accumulator 445. However, the holding pressure does not necessarily have to be adjustable.

Further, as described above, when the molding of the prepreg is completed, the pressure of the cylinder portion 420 becomes higher than the pressure of the accumulator 445, so that the holding pressure becomes lower than the molding pressure, but the enclosed gas pressure of the accumulator 445. The holding pressure can be made substantially the same as the molding pressure by sufficiently increasing the pressure and making the cross section of the connecting flow path connecting the cylinder portion 420 and the accumulator 445 sufficiently large.

However, if the filling gas pressure of the accumulator 445 is excessively increased in order to increase the holding pressure, the inflow of hydraulic oil from the cylinder portion 420 to the accumulator 445 is suppressed. Therefore, when the prepreg is sandwiched between the molds 200 and 300, the impact force applied from the upper mold 200 to the lower mold 300 cannot be sufficiently relaxed, and the bounce cannot be sufficiently suppressed depending on the lead angle of the screw. There is a risk. Therefore, the holding pressure is preferably set to be lower than the molding pressure.

As described above, in the present embodiment, the molding pressure applied to the prepreg when the molding is completed is accumulated in the accumulator 445 to suppress the bounce and to form the holding pressure corresponding to the pressure of the accumulator 445. Can be added to prepreg PPF. In general, increasing the pressure applied from the molds 200, 300 to the prepreg PPF can increase the heat transfer coefficient between the molds 200, 300 and the prepreg PPF. Therefore, according to the present embodiment, a sufficiently high holding pressure can be applied to the prepreg PPF to cool the prepreg PPF more quickly, so that the holding time after the completion of molding can be shortened.

In the present embodiment, the solenoid valve 444 is opened as shown in FIG. 4D after a preset holding time has elapsed from the time when the molding of the prepreg is completed as shown in FIG. 4C. At the same time, the bidirectional pump 442 is driven to deliver hydraulic oil from the solenoid valve 444 side to the oil tank 441. As a result, the hydraulic oil flows out from the accumulator 445, so that the pressure of the accumulator 445 decreases, and the load that pushes up the piston portion 410 decreases. Therefore, the upward load applied to the slide 120 (FIG. 2) from the piston portion 410 via the lower mold 300, the prepreg PPF, and the upper mold 200 is reduced, and the stick state of the screw 140 and the slide 120 is released. To.

By releasing the stick state of the screw 140 and the slide 120 in this way, the screw 140 can be rotated. Therefore, the molding process is completed by rotating the screw 140 to raise the slide 120 and the upper mold 200 and taking out the molded prepreg PPF.

A5. Evaluation of molding equipment operation:
FIG. 5 is a graph showing the result of evaluating the operation of the molding apparatus 10 (FIG. 2) of the present embodiment. The graph shown in FIG. 5 shows the load applied to the lower mold 300 and the time change of the position (slide position) of the slide 120. In the graph of FIG. 5, the horizontal axis represents time, and the left vertical axis and the right vertical axis represent the load and the slide position, respectively.

In the evaluation, first, hydraulic oil was supplied to the accumulator 445 (FIG. 3) to increase the pressure of the accumulator 445, and the load applied to the piston portion 410 by the initial pressure of the hydraulic oil was set to 10 kN. The slide 120 was then lowered to bring the upper die 200 into direct contact with the lower die 300 (ie, without sandwiching the prepreg). Then, in these series of processes, the load applied to the lower mold 300 and the position of the slide 120 were actually measured.

As a result, as shown in the graph of FIG. 5, the load applied to the lower mold 300 increased from t1 at the time when the molds 200 and 300 came into contact with each other, and showed a peak of 1440 kN at t2 after 0.017 s. Then, the load gradually decreased from the time point t2 when the load peaked to the time point t3 when 0.026 s passed, and then the load was maintained at about 440 kN.

On the other hand, the slide position is lowered with the lowering of the piston portion 410 (see FIG. 4C) even after the time t1 when the molds 200 and 300 come into contact with each other, and the time point t2 when the load peaks, that is, the slide. It sank once at a time corresponding to the time when 120 reached the lower end position and the molding of the prepreg was completed. After that, the slide position returned upward from the once sunk state. It should be noted that such subduction of the slide position is sufficiently high for the slide 120 from the time point t1 when the molds 200 and 300 come into contact to immediately before the time point t2 (the time point when the frame 120 reaches the vicinity of the lower end position). Since it is descending at a descending speed, it is probable that a strong impact force is applied from the upper die 200 to the lower die 300, and the impact force and the reaction force cause the frame 110 to extend in the vertical direction.

In this way, the load applied to the lower mold 300 was held at 440 kN after showing a peak at the time point t2 from the time point t1 when the load rises. Further, at the time point t2, the slide position showed a slight subduction due to the extension of the frame 110, but no upward movement due to the bounce was observed. From these results, it was confirmed that the occurrence of bounce can be satisfactorily suppressed by applying this embodiment.

Further, after the load peaks at the time point t2 and after the time point t3 when the load gradually decreases, the load applied to the lower mold 300 (corresponding to the pressure applied to the molded prepreg PPF) is maintained in a sufficiently high state. Was made. From this, it was confirmed that if the present embodiment is applied, the cooling rate of the molded prepreg PPF can be made faster, and the holding time after the prepreg molding and the cycle time of the entire molding process can be shortened. did it.

B. Modification example:
The present invention is not limited to the above embodiment, and can be implemented in various aspects without departing from the gist thereof. For example, the following modifications are also possible.

B1. Modification 1:
In the above embodiment, as shown in FIG. 4D, after the holding time has elapsed, the hydraulic oil is discharged from the accumulator 445 to the oil tank 441 to reduce the pressure of the accumulator 445 and the pressure of the cylinder portion 420. However, in general, it is sufficient if the pressure of the cylinder portion 420 can be reduced. For example, a first solenoid valve is provided between the accumulator 445 and the connection port 428 (FIG. 3) of the cylinder portion 420, and an intermediate portion between the first solenoid valve and the connection port 428 and an oil tank 441 are provided. A flow path having a second solenoid valve may be provided between them. In this way, by closing the first solenoid valve and then opening the second solenoid valve, the pressure of the cylinder portion 420 is reduced without lowering the pressure of the accumulator 445. be able to.

B2. Modification 2:
In the above embodiment, as shown in FIG. 3, the accumulator 445 is connected to the flow path from the solenoid valve 444 to the connection port 428, that is, the connection flow path connected to the oil chamber 249 of the cylinder portion 420. , The accumulator 445 can be omitted. However, in this case, it becomes difficult to adjust the holding pressure, and depending on the setting of the initial pressure applied to the hydraulic oil in the connecting flow path, the molding pressure may not be properly accumulated. Therefore, it is preferable to connect the accumulator 445 to the connection flow path as in the above embodiment.

B3. Modification 3:
In the above embodiment, as shown in FIG. 3, a cushion device having a piston portion 410, a cylinder portion 420, and a hydraulic circuit 440 is used to accumulate a strong molding pressure applied to the prepreg at the end of molding to accumulate molds 200, 300. A holding pressure is applied to the prepreg PPF sandwiched between (FIG. 4), but the molding apparatus may be any as long as it can accumulate the molding pressure and apply the holding pressure. For example, it is also possible to provide a mechanism for accumulating the molding pressure in the cylinder portion and apply the holding pressure by using the mechanism.

B4. Modification 4:
In the above embodiment, the stick state of the screw 140 and the slide 120 is maintained in the state where the holding pressure is applied to the prepreg PPF, but the lead angle of the screw is adjusted to be large or the holding pressure is set to be low. Then, the stick state of the screw 140 and the slide 120 can be released in a state where the pressure applied to the prepreg PPF becomes the holding pressure. However, in this case, since the holding pressure is applied to the prepreg PPF, it becomes necessary to drive the servomotor 153 so as to apply torque to the screw 140, which complicates the control of the servomotor 153. Therefore, it is preferable that the stick state of the screw 140 and the slide 120 is maintained in a state where the holding pressure is applied to the prepreg PPF as in the above embodiment.

B5. Modification 5:
In the above embodiment, the press device 100 (FIG. 2) uses a servo screw press device in which the screw 140 is driven by the servo motor 153 (FIG. 1), but the press device includes the servo screw press device and others. It is also possible to use various screw press devices such as a screw press device using a flywheel. However, it is preferable to use a servo screw press device as the press device because it is possible to control the descending speed of the slide 120 to manufacture a higher quality prepreg product.

B6. Modification 6:
In the above embodiment, the present invention is applied to the molding of a prepreg PPG in which a CFRTP sheet (hereinafter, also simply referred to as “sheet”) impregnated with a matrix material is laminated on a carbon fiber woven fabric. In addition to molding prepreg PPG, prepreg in which a sheet impregnated with a matrix material is laminated on a bundle of carbon fibers arranged in one direction, a single-layer sheet of CFRTP, or a sheet in which carbon fibers are contained only in a part of the matrix material. It can also be applied to the molding of prepreg, or the additional molding of already molded CFRTP material. Since these prepregs, single-layer sheets, CFRTP materials, etc. are all objects of molding, they can be collectively referred to as "materials to be molded".

B7. Modification 7:
In the above embodiment, the present invention is applied to the molding of CFRTP, but in addition to CFRTP, the present invention includes a glass fiber reinforced thermoplastic resin using glass fiber as a reinforcing fiber and an aromatic polyamide resin as a reinforcing fiber. It can be applied to the molding of various fiber-reinforced thermoplastic resins such as fiber-reinforced thermoplastic resins using the above fibers.

B8. Modification 8:
In the above embodiment, the present invention is applied to stamping molding of CFRTP, but the present invention can be generally applied to molding such as deep drawing in addition to stamping molding.

10 ... Molding device 100 ... Press device 110 ... Frame 111 ... Outer shell plate 112 ... Inner shell plate 113 ... Top plate 114 ... Shaft fixing member 115 ... Thrust bearing 116 ... Bushing 119 ... Opening 120 ... Slide 121 ... Slide body 122 ... Female screw plate 128 ... Female screw 129 ... Hole 130 ... Bolster 140 ... Screw 141 ... Shaft 142 ... Large diameter part 143 ... Male screw 150 ... Rotation drive part 151 ... Pulley 152 ... Toothed belt 153 ... Servo motor 160 ... Slide guide 170 ... Balancer 171 ... Balance cylinder 172 ... Cylinder rod 173 ... Connection arm 200 ... Upper mold 300 ... Lower mold 400 ... Cushion device 410 ... Piston part 411 ... Pressure receiving part 412 ... Mold mounting part 420 ... Cylinder part 428 ... Connection port 429 ... Oil chamber 430 ... Holding ring 440 ... Hydraulic circuit 441 ... Oil tank 442 ... Bidirectional pump 443 ... Servo motor 444 ... Electromagnetic valve 445 ... Accumulator 910 ... Heating device PPG, PPF ... Prepreg

Claims (8)

A molding device for molding a fiber-reinforced thermoplastic resin to be molded material containing a thermoplastic resin matrix material and reinforcing fibers.
A frame, a screw in which vertical movement with respect to the frame is restricted and a male screw is formed, a slide in which a female screw that meshes with the male screw is formed, and a bolster arranged below the slide and fixed to the frame. And a screw press device configured to raise and lower the slide by rotating the screw.
A cushion device attached to the upper side of the bolster and
The matrix is formed by sandwiching the material to be molded, which is attached to the lower side of the slide and the upper side of the cushion device, respectively, and heated to a temperature higher than the melting point of the matrix material. Upper and lower molds set below the melting point of the material,
With
The cushioning device accumulates the molding pressure applied to the material to be molded when the molding of the material to be molded is completed, so that the material to be molded is sandwiched between the upper mold and the lower mold. It is configured to apply a holding pressure equal to or lower than the molding pressure.
The lead angles of the male screw and the female screw are such that the screw and the slide are in a stick state when the frame extends in the vertical direction and an upward load is applied to the slide at the end of molding of the material to be molded. Is set to be,
Molding equipment. The molding apparatus according to claim 1, wherein the stick state of the screw and the slide is maintained in a state where the holding pressure is applied to the material to be molded. The molding device according to claim 1 or 2, wherein the cushion device is configured so that the holding pressure can be adjusted. The molding apparatus according to any one of claims 1 to 3.
The cushion device is
A cylinder part where a liquid chamber is formed and attached to the bolster,
A pressure receiving portion housed in the liquid chamber and generating an upward load by the pressure of the working liquid in the liquid chamber, a mold mounting portion provided on the upper side of the pressure receiving portion and to which the lower mold is mounted, and a mold mounting portion. And the piston part with
A fluid circuit connected to the liquid chamber of the piston portion and
Have and
The fluid circuit is configured so that the connection flow path connected to the liquid chamber can be closed while the initial pressure is applied to the working liquid.
Molding equipment. The molding apparatus according to claim 4, wherein the fluid circuit has an accumulator connected to the connection flow path. The molding apparatus according to any one of claims 1 to 5, wherein the slide is driven so that the descending speed in the vicinity of the lower end position of the slide at which molding of the material to be molded is completed is 100 mm / s or more. The molding device according to any one of claims 1 to 6, wherein the screw press device is a servo screw press device that drives the rotation of the screw by a servo motor. A molding method for molding a fiber-reinforced thermoplastic resin to be molded material containing a thermoplastic resin matrix material and reinforcing fibers.
A heating step of heating the material to be molded to a temperature higher than the melting point of the matrix material, and
A molding step of molding the material to be molded by sandwiching the heated material to be molded between the upper mold and the lower mold whose temperature is set to a temperature lower than the melting point of the matrix material.
With
In the molding step, the frame, the screw in which the vertical movement with respect to the frame is restricted, the screw on which the male screw is formed, the female screw that meshes with the male screw are formed, the slide to which the upper mold is attached, and the lower mold It is performed using a screw press device that has a bolster attached and secured to the frame below the slide and is configured to raise and lower the slide by rotating the screw.
The molding process is
When the molding of the material to be molded is completed, the molding pressure applied to the material to be molded is accumulated to accumulate the molding pressure.
Due to the accumulated molding pressure, a holding pressure equal to or lower than the molding pressure is applied to the material to be molded sandwiched between the upper mold and the lower mold.
Including the process,
The lead angles of the male screw and the female screw are such that the screw and the slide are in a stick state when the frame extends in the vertical direction and an upward load is applied to the slide at the end of molding of the material to be molded. Is set to be,
Molding method.

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