JPH0243616B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a fiber-reinforced thermosetting resin (hereinafter referred to as FRP).
This invention relates to a method for manufacturing a cylindrical molded product. Conventionally, the manufacturing methods for FRP cylindrical molded products are the filament winding method (FW method), in which the molding is performed on the outside of the cylindrical mold, and the conversely, the centrifugal method, in which the molding is performed inside the cylindrical mold using centrifugal force. Molding methods are known. Although the FW method has been widely used for a long time, it has drawbacks such as poor material yield, working environment, ease of generating voids, and unidirectionality of fiber reinforcement. On the other hand, in the centrifugal molding method, in order to uniformly mix the reinforcing material and resin, the rotation speed is generally 60 revolutions per minute or more when molding a cylindrical body with a diameter of 2 m, that is, a centrifugal force of about 4 times the gravity or more. The rotation speed is such that the molded cylindrical product has few voids, has a constant outer circumferential dimension, has a beautiful appearance, and has low material scattering, resulting in a low material yield. It has the advantage of excellent performance and a good working environment. However, this centrifugal molding method requires a large amount of energy because the mold is rotated at high speed, and has the disadvantage that the precision and strength of the mold itself must be made stricter. In addition, a fatal defect is that the supplied fiber reinforcement is arranged in the circumferential direction, so the strength ratio of the molded product in the axial direction and the circumferential direction is significantly different, that is, generally 1/2 to 1/3 This results in a poor strength balance. Furthermore, there remains a fear that the fibers will separate into two layers due to the rotational speed, the fiber reinforcement material, mainly the difference in specific gravity between the glass fibers and the liquid resin. In order to improve this defect,
In No. 111577, the FRP molding material supply unit is installed so that it can be moved relative to the mold, and the mold is rotated at 1 to 4 revolutions/min (peripheral speed of 5 to 10 m/min) to align with the center axis of the mold. A press roll is installed in parallel and lowered from its central axis, and the rotation of the cylindrical mold and the rotation of the press roll are adjusted to the same rotation speed from the drive unit using a chain wheel to form the mold, and the press roll is A method has been proposed in which an air cylinder is installed on the upper part of the roll and the roll is moved up and down by air pressure, that is, pressurized and impregnated with the supplied material while adjusting the roll by pressing and releasing the pressure. This method is superior to the conventional centrifugal molding method in that it uses a relatively small power source, can be molded with a simple mold, and is superior in that it produces cylindrical molded products with little variation in material strength due to directionality. It's a method. However, in this forming method, since the press roll used has grooves in the generatrix direction, spirally, or in a grid pattern, the fiber reinforcement accumulates in the grooves and adheres to the rolls, resulting in poor forming efficiency. The disadvantage is that the thickness of the molded product varies widely and many air bubbles remain in the molded product. The present inventors have developed a molding machine that rotates with a small centrifugal force, that is, can be molded at low speed rotation of 1 to 30 revolutions/min, and at a circumferential speed of 0.5 to 200 m/min, and has excellent molding efficiency by removing air bubbles contained in the molding material. As a result of intensive research on the method of molding FRP cylindrical products, we found that there were many regular and/or irregularly shaped recesses on the surface, and the above conditions were satisfied by using at least one pressure roll whose recesses were not grooves. We have discovered a manufacturing method to do so. That is, the present invention supplies fiber reinforcing material and liquid thermosetting resin to the inner wall surface of a cylindrical mold that rotates at a speed that generates a centrifugal force smaller than twice the force of gravity, and The surface is formed by pressing with at least one press roll in which there are many regular and/or irregularly shaped concave portions, the concave portions of which are not groove-like, to sufficiently impregnate the reinforcing material with the resin and defoaming it. A method for manufacturing a cylindrical molded article is provided. The cylindrical mold used in the present invention is preferably one that can be split into at least two parts along the rotation axis direction and can be closed on the outside with a tightening bolt.
Usually, the cross section is a circle, ellipse, polygon, or partially missing one of these. Materials for this mold include metal, wood, plastic, stone, etc., with metal being particularly preferred. The size of this mold is not particularly limited, but it is usually about 1 to 4 m in inner diameter and 1 to 10 m in length, considering the molding inside the mold and the transportation of the molded product. Of course, the diameter and length can also be outside the above range. In the present invention, a supply section for the fiber reinforcing material and liquid thermosetting resin is placed inside the mold, and the supply section can be moved freely back and forth, or the supply section can be fixed and the mold itself can be moved. Designed to move back and forth. Further, the mold according to the present invention is rotated by a plurality of rollers driven by a motor. The rotational speed at this time is selected to be a speed that generates a centrifugal force smaller than twice the weight of gravity, preferably 1.2 times the weight or less, and optimally a speed that generates a centrifugal force smaller than the weight of gravity. Generally, the centrifugal force on the wall of a rotating body is F=
It is determined by mγω ² . In this case, F is the centrifugal force, m is the unit mass, γ is the radius of the rotating body, and ω is the angular velocity. If a cylindrical mold with an inner diameter of 2 m is rotated at a speed of 60 revolutions per minute to produce an FRP cylindrical molded product, the centrifugal force acting on a 1 cm ³ unit of the molded material will be 7.24 g, assuming the specific gravity of the molding material is approximately 1.8.・cm/s ² , and the gravity is F=mα... (Note: α is acceleration)
It is calculated as 1.8 g cm/s ² , which is about 4 times the force of gravity. In this case, for the centrifugal force to be twice the gravity, the rotation speed is 42 revolutions/minute and the circumferential speed is 266
m/min. According to the experiments conducted by the present inventors, in the general centrifugal molding method, it takes 2 of the gravity to prevent the supplied molding material from falling from the mold.
A centrifugal force of more than twice, preferably four times or more is required; if the centrifugal force is less than that, it will be difficult to press the molding material against the wall. From the above, it can be seen that the mold of the present invention has a speed of 1 to 30 revolutions per minute, although it is not necessarily accurate because it varies depending on the inner diameter.
Preferably 1 to 18 revolutions/min, more preferably 1 to 18 revolutions/min.
Rotation speed of about 15 revolutions/minute or circumferential speed of 0.5~
Rotates at 300m/min. The fiber reinforcement used in the present invention is glass fiber,
Known fiber reinforcing materials such as carbon fiber and aramid fiber (manufactured by DuPont, Kepler fiber) can be used, and glass fiber is particularly preferred. Such reinforcing materials are used in the form of pine, roving, or chops made by cutting roving into appropriate lengths.
It is also possible to use them in combination.
In addition, the amount of reinforcing material used in the present invention is usually the same as that in the molded product.
A suitable amount is 10 to 80% by weight, preferably 15 to 60% by weight, more preferably 20 to 50% by weight. Examples of the liquid thermosetting resin used in the present invention include known liquid thermosetting resins such as unsaturated polyester resins, epoxy resins, phenol resins, and vinyl ester resins, with unsaturated polyester resins being particularly preferred. When using this unsaturated polyester resin, it is preferable to use a method of curing using a combination of a peroxide or the like as a catalyst and a metal salt, an amine, or the like as a curing accelerator. Such catalysts and curing accelerators may be supplied onto the fiber reinforcing material on the inner surface of the mold separately from the resin or mixed in advance. In addition, liquid thermosetting resin has the ability to impregnate fiber reinforced materials,
Viscosity is important because of the sag phenomenon. In other words, if the resin viscosity is too low, the molded product tends to whiten or sag, while if it is too high, impregnating properties are poor, so even when the molding material is pressed with a roller, it does not stick to the mold surface. It will fall and will not be able to be molded. From this point of view, the viscosity of such resin is usually
The viscosity is appropriately selected from 0.5 to 20 poise/25°C (Bruck-Field viscosity), preferably 1.0 to 15 poise/25°C, and more preferably 2 to 10 poise. The press roll used in the present invention has a large number of regular and/or irregularly shaped recesses on its surface, and the recesses are not groove-like. It is something that you have.
Since the length of the fiber reinforcement material that meets the strength required for the final cylindrical molded product is usually about 50 mm, such rolls are
30mm, preferably 2-10mm and 1-30 in circumferential direction
mm width, 1 mm or more depth, preferably 2 to 30 mm
It is suitable that the roll area has regular and/or irregularly shaped recesses of 30 to 90%, preferably 50 to 80%, of the roll area. The roll generatrix direction width and circumferential direction width of the recessed portion may be the same or different as long as they are within the above range, and the shape thereof may be triangular, quadrilateral, pentagonal, other polygonal, circular, oval, or oval. , cross-shape, X-shape and others. Note that the recesses on the surface of the pressure roll are discontinuous with each other and are separated by projections at appropriate intervals. Specific shapes of the concave portions of the above-mentioned pressure roll include those shown in FIGS. 8 and 9, and these can be formed by cutting the roll surface, molding at the same time as the roll is manufactured, punching with a press, etc. It is formed when winding a metal plate or plastic sheet having an uneven surface around a roll surface, winding a wire mesh or plastic mesh around a roll surface, winding a perforated pipe around a roll surface, etc. Preferably, the pressure roller is not swollen or corroded by liquid thermosetting resins or cleaning organic solvents, has a thickness of 0.5 to 5 mm, and has a mesh size of 2 to 8 mm because it is easy to manufacture, inexpensive, and easy to repair. It is preferable to use at least one thermoplastic plastic, such as polyethylene, polyester, polyamide, etc., or a metal mesh wrapped around the roller surface. The material of the roll used in the present invention may be any material as long as it can generate the above-mentioned pressing force, and examples thereof include known materials such as iron, aluminum, stainless steel, copper, wood, and plastic, and combinations thereof. I can't help it. Further, the inside of the roll may be empty or not. Further, when winding the uneven material around the roll surface, the materials may be the same or different. When the press roll presses the fiber reinforcing material and liquid thermosetting resin applied to the inner surface of the mold, the reinforcing material and liquid thermosetting resin temporarily remain in the recesses of the roll. If the angle of the upper opening edge of the recess that comes into contact with these is acute, the molding material will easily become entangled, making molding difficult.
Preferably, the angle of the upper opening edge of the recess is an obtuse angle, or the edge is cut into a flat surface, or has a curved shape of 1R or more. The pressure roll used in the present invention may be simply attached to a fixed arm, but preferably its vertical movement is controlled by an air cylinder, spring, gear, etc.
It is attached to an arm that is appropriately adjusted with a cam, etc.
More preferably, the roll itself is removable from the arm, and is mounted in such a way that it can move to some extent independently of the movement of the arm. An example of installing such a pressure roll is shown in the first example.
Shown in Figure 3. In the molding method of the present invention, an important step is the step of impregnating the fiber reinforcing material with the liquid thermosetting resin by pressing the surface of the molding material with a pressure roll having specific recesses on the surface. This step may be carried out by applying a constant pressure to the pressure roll using an air cylinder, but it is preferably carried out using the pressure roll's own weight. When the pressure roll presses with its own weight, it is necessary to provide a mechanism that allows the pressure roll to rotate freely, as shown in FIG. 5, for example. At this time, the pressure roll may be adjusted by at least one crank, a shaft that can move in an appropriate width, or a combination thereof so that it can freely move forward and backward with an appropriate width. desirable. When such a roll presses the molding material, the rotation of the press roll is not artificially manipulated, and can respond to modulation of rotational speed due to resistance of the molding material, etc., while being synchronized with the rotation of the mold. In the present invention, the pressure roll is employed to sufficiently impregnate the fiber reinforcement material with the liquid thermosetting resin in the molding material. It is okay to apply some load as long as it does not interfere with the free rotation of the press roll, but if the load is too large or the roll itself is heavy, the rotation speed of the mold body will be slow and the roll will not work properly. This is not preferable because it sinks into the molding material and squeezes out the resin, resulting in a molded product with a low resin content. Conversely, if the weight or load of the press roll is small, resin impregnation will be insufficient, air bubbles will remain in the molding material, and the material will fall from the mold surface, making molding impossible. Therefore, the pressure roll used in the present invention usually has a length of 10 to 100 cm, preferably 30 to 70 cm, and its own weight is 20 to 600 g, preferably 50 to 400 g, more preferably 50 to 400 g per cm of roll length. It is suitable that a load of 80 to 300 g, that is, a pressing force is applied to the surface of the molding material. In order to efficiently achieve resin impregnation and air bubble defoaming using such rolls, it is preferable to use three or more of the above rolls at appropriate intervals in the present invention. As for the shape of the press roll, its length is as described above, but it can be changed as appropriate depending on the length of the molded product, and its diameter is preferably smaller than the inner diameter of the mold body. It has a size that allows it to rotate freely inside, and a diameter of 5 to 40 cm is usually appropriate. Next, an example of the manufacturing method of the present invention will be explained with reference to the drawings. As shown in FIG. 1, a molding mold body A is rotated by a roller 5 that transmits the rotation of a motor 4, and a reciprocating sliding body C having a press roll, a molding material supplying part, etc. therein is a cantilevered beam. A device is used that can move back and forth along the body B. Alternatively, as shown in FIG. 3, the molding material supply part and the mounting part of the press roll are fixed without moving along the cantilever beam B, and the mold body A is rotated, and at the same time the molding is performed. A device is used that can be moved back and forth by a mold movement motor 11 controlled by a self-propelled motor control panel 15 as it progresses. In the mold body A, the reinforcing material entered from the fiber reinforcing material receiving port 7 is cut by the reinforcing material cutter 8 and dropped onto the inner surface of the mold, and then resin, catalyst, etc. are supplied from the liquid thermosetting resin supply device E. is applied onto the reinforcement. After that, the press roll F presses the molding material. At this time, the pressure roll F is designed to have some play due to the pressure roll bearing 30 and crank 29 as shown in FIG. The mold body A or the reciprocating sliding body C moves as molding progresses to form a molded product, and a cylindrical product is produced after the liquid thermosetting resin is cured. Thereafter, the tightening bolts 2 and 3 of the mold body A are removed, the mold body A is opened in half, and the cylindrical molded product is taken out. According to the production method of the present invention, the cylindrical molded product obtained is made of FRP, but it is also made of plastic foam,
By supplying resin concrete, etc., it is also possible to form cylindrical molded products with multilayer shapes such as two-layer or three-layer (sandwich-like). With the method of the present invention, it is possible to efficiently form a cylindrical molded product with excellent strength and few bubbles because the resin is evenly impregnated and the fiber reinforcing material is uniformly dispersed. The obtained cylindrical molded product is useful as containers such as tanks, septic tanks, and silos. Next, the present invention will be described in detail with reference to Examples.
Note that parts and percentages in the examples are based on weight. Example 1 Using manufacturing equipment as shown in Figures 1, 2 and 5,
Cylindrical type A with a diameter of 2.8 mφ and a length of 3.5 m is set at a peripheral speed of 22.5
m/min, and glass fibers (glass roving SP
-3, manufactured by Asahi Fiber) was cut into chopped strands with a length of 50 mm and fed at a rate of 5 kg/min, and then unsaturated polyester resin (Polylite FG-104, 100 parts (manufactured by Dainippon Ink & Chemicals), 0.4 parts of 6% cobalt naphthenate (manufactured by Dainippon Ink & Chemicals) as an accelerator, and 1.0 part of 55% methyl ethyl ketone peroxide (manufactured by NOF) as a catalyst were mixed at 10 kg/min. It was supplied by Furthermore, as shown in Figures 8-b and 9, there is a recess with a depth of 5 mm, length and width of 5 mm, and an upper open edge having a curved surface shape of 1R, and the interval between the upper and lower recesses and the left and right recesses. It was pressed with three steel pressing rolls having a diameter of 2 mm. This pressing roll has a diameter of 15 cm and a length of 60 cm.
cm and weighed 10 kg, and the distance between the three rolls was 10 cm each. Incidentally, the reciprocating sliding body to which the supply section for glass fibers, resin, etc. and the pressure roll were attached was moved at a speed of 30 cm/min along the mold rotation axis. The obtained cylindrical molded product has a length of 3.5 m, a diameter of 2.8 m,
It had a wall thickness of 8 mm. The empty rate of this thing,
Table 1 shows the presence or absence of entanglement of the molding material with the press roll, the molding time, and the presence or absence of slippage of the molding material on the inner surface of the mold. Example 2 A press roll was placed on the surface of a smooth steel roll with a diameter of 15 cm, a length of 60 cm, and a weight of 8 kg. Polypropylene steel (No. 10-1) with a wire diameter of 2 mm and a mesh size of 5 mm x 5 mm
A cylindrical molded product was obtained in the same manner as in Example 1, except that the material (Fig. a) was replaced with a double-wound product (weighing 8 kg). In addition, various characteristics are shown in Table-1. Example 3 A press roll was placed on the surface of a smooth steel roll with a diameter of 15 cm, a length of 60 cm, and a weight of 8 kg, as shown in Fig. 10-a, with a corner of each side having a length of 8 mm, a wide angle of 120 degrees, and a narrow angle of 60 degrees. The process was carried out in the same manner as in Example 1, except that the concave portions were rounded to a radius of 1 shaku, and each concave portion was wound with a 3 mm thick aluminum plate punched out by a press (weighing 9 kg) with a side spacing of 3 mm. A cylindrical molded product was obtained. In addition, various characteristics are shown in Table-1. Comparative Examples 1 to 3 In Example 1, the press roll was replaced with one having grooves of 4 mm depth and 3 mm width on the roll surface at 2 mm intervals in the axial and circumferential directions of the roll. In addition, the results of an example in which the material supply rate was 7.5 kg/min (Comparative Example 2) and an example in which the number of rolls was 5 in Comparative Example 2 (Comparative Example 3) are also shown. -1.

[Table] 〓 Specific gravity of glass
Specific gravity of resin 〓

[Brief explanation of the drawing]

The drawings show an example of an apparatus used to carry out the method for manufacturing a molded article according to the present invention, and FIG. 2 is a side view of the device shown in FIG. 1, and FIG. 3 is a side view of the device shown in FIG. 1, and FIG. 3 is a side view of the device shown in FIG. FIG. 4 is a front view of the part to which the press roll is attached, FIG. 5 is a partial side view of FIG. 4, and FIG. 6 is a front view of the molding device. FIG. 7 is a side view showing a portion where the pressure roll is attached so as to be freely movable up and down. Also, the 8th
The figure is a perspective view of a pressure roll having recesses formed on the roll surface that can be used in the present invention, FIG. 9 is an enlarged view showing the shape of the recesses on the pressure roll surface of FIG. 8, and FIG. 11 is a plan view showing the shape of the concave portion of the press roll that can be used in the present invention. FIG. The figure is a plan view showing the overlapping state of the linear objects constituting the net in figure 9-b.
The figure is a side view showing the state of connection between the pressure roll and the crank or arm. Notes A...Mold body, B...Cantilever beam body, C...
Reciprocating sliding body, D... fiber reinforcement supply device, E...
Liquid thermosetting resin supply device, F...press roll,
G...Mold frame section, H...Forming material supply section and press roll mounting section, I...Rail, 1...Hinge section, 2...Tightening bolt, 3...Tightening bolt, 4...Motor , 5... Roller, 6... Support, 7... Fiber reinforced material receiving port, 8... Reinforcement cutter, 9... Fiber reinforced material falling port, 10... Mold inner surface, 11... Mold rotation motor, 12...Reducer for mold rotation, 13...Motor for moving mold, 14...
Mold movement reducer, 15...Self-propelled motor control panel,
16...Bearing, 17...Form gear for traverse, 18...Reinforcement cutter drive motor, 19...Resin supply nozzle, 20...Air cylinder, 21...Arm, 22...Reinforcement material cutting resin pressure roller , 23... fiber reinforced material, 2
4...Iron presser roller for preventing reinforcement material from coming off, 25
... Air cylinder for cutting reinforcement material, 26 ... Rotating pulley for cutting reinforcement material, 27 ... Motor, 28
...Resin supply nozzle, 29...Crank, 30...
... Press roll bearing, 31 ... Press roll shaft rod, 3
2...Cut-circular internal mold material, 33...Roll fall prevention member, 34...Concave portion, 35...Plane portion, 36...
Net composition wire rod, 37...spring.

Claims (1)

[Claims] 1. A fiber reinforcing material and a liquid thermosetting resin are supplied to the inner wall surface of a cylindrical mold that rotates at a speed that generates a centrifugal force smaller than twice the force of gravity, and the surface of the material made of such reinforcing material and resin is A number of regular and/or irregularly shaped recesses are present in the reinforcing material, and the recesses are pressed by at least one non-grooved pressing roll to sufficiently impregnate the reinforcing material with resin and defoaming it before molding. A method for manufacturing a cylindrical molded product.