JPS5933118A - Manufacture of cylindrical molded item - Google Patents

Abstract

PURPOSE:To obtain a cylindrical molded item free from voids and the strength of which is rather uniform, by feeding a fiber reinforcing material and a resin into a cylindrical mold, and pressing them by rolls located inside the cylindrical mold so that the reinforcing material is well impregnated with the resin. CONSTITUTION:The cylindrical mold A is rotated at such a velocity (e.g. a rotational velocity of 1-15 r.p.m or a circumferential velocity of 0.5-300m/min) that a centrifugal force that is lower than twice the gravity is generated, a fiber reinforcing material and a liquid thermosetting resin are fed to the inner surface of the rotating cylindrical mold A, at least one press roll F that is freely rotated is allowed under its own weight to press the surface of the molding material consisting of the fiber reinforcing material and the resin so that the reinforcing material is impregnated with the resin and thereafter the resin is thermoset to be molded.

Description

[Detailed Description of the Invention] The present invention is a fiber-reinforced thermosetting resin (hereinafter abbreviated as FRP).
This invention relates to a method for producing 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 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 adopted since ancient times,
It has drawbacks such as material yield, working environment, ease of generating voids, and unidirectionality of fiber reinforcement.

On the other hand, the centrifugal molding method is generally used to uniformly mix the reinforcing material and the resin, for example when molding a cylindrical body with a diameter of 2 m.

The process is carried out at a rotation speed of 60 revolutions per minute or more, that is, a centrifugal force of about 4 times the force of gravity, and the molded tubular product has few voids and can be produced with a constant outer dimension. Moreover, it has a beautiful appearance, and has the advantage of a good material yield and a good working environment because there is little material scattering. However, this centrifugal molding method requires a large amount of energy because it rotates at high speed, and the precision of the mold itself
There is a drawback that the strength must be made more strict. or,
A fatal flaw is that the fiber reinforcement material supplied is lined up in the circumferential direction, resulting in a molded product having a significantly different strength ratio between the axial direction and the circumferential direction, that is, generally 1/2 to 1/3 of the strength. This results in an imbalance. Furthermore, there remains a fear that the fibers will separate into two layers due to the rotational speed, the fiber reinforcing agent, and mainly the difference in specific gravity between the glass fiber and the liquid resin.

In order to improve this defect, Japanese Patent Application Laid-Open No. 54-11157
In No. 7, the material supply for FRP molding is installed so that it can move relative to the mold, and it rotates 1 to 4 rotations and 5 to 1 rotation in parallel.
The mold is rotated at a speed of 0 m/min), a suppression roll is installed parallel to the central axis of the mold and lowered from the central axis, and
The rotation of the cylindrical mold and the rotation of the pressure roll are adjusted to the same rotational speed using a chain wheel from the drive unit, and molding is performed.
Moreover, a method has been proposed in which an air cylinder is installed on the top of the press roll and the roll is moved up and down by air pressure, that is, pressurized or released to adjust the pressure while suppressing and impregnating the supplied material and forming the roll. There is. This method uses a smaller gravity source than the conventional centrifugal molding method, can be molded with a simple mold, and is an excellent manufacturing method that produces cylindrical molded products with less variation in material strength due to directionality. It is.

However, this molding method has the disadvantage that it must be carried out at exactly the same rotational speed of the mold and the pressure roll.

In other words, it is extremely difficult to rotate them in perfect synchrony because the diameters of the mold body and the suppression roll are different, and the diameter of the cylindrical body gradually decreases. The supplied material becomes lumpy or has hangnails. Especially when the inner diameter is 1.5 to 3 m, the circumferential speed is 1.
If the speed is 0 m/min or more, problems tend to occur. In such a case, the method is to raise the air cylinder to avoid the bump-shaped part and press it again with a roll. Molding by pressing and releasing in this manner is cumbersome and inefficient in production, and in addition, it is difficult to obtain a molded product with uniform wall thickness. In addition, if the mold dimensions change using this method, it is necessary to adjust the rotational speed of the mold and the pressure roll to be the same each time.Furthermore, since the pressure impregnation is performed using an air cylinder, the fiber reinforcement material Slight variations in resin viscosity due to the influence of content, outside temperature, etc. require adjustment of the pressing force, but it is extremely difficult in terms of production to immediately change the pressurizing conditions in response to changes in the above factors. Furthermore, since the power source for the pressing force is pneumatic pressure, it is mechanically complex, and since a chain wheel is used to synchronize the pressure roll with the mold, cleaning at the end of molding is extremely difficult.

If left as is, the resin will harden and subsequent production will no longer be possible.

We rotate with small centrifugal force, i.e. 1 to 3
It can be molded at low rotation speeds of 0 rotations/min and circumferential speeds of 0.5 to 200 m/min, removes air bubbles contained in the molding material, has a constant axial/circumferential strength ratio, and has a uniform wall thickness. Moreover, as a result of intensive research into a method of molding a cylindrical FRP product using a simple device, we have discovered a manufacturing method that satisfies the above conditions.

That is, one aspect of the present invention is to supply a fiber reinforcing material and a 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. To provide a method for producing a cylindrical molded article, characterized in that the surface of the material is sufficiently impregnated with a reinforcing material with a resin pressed by the weight of at least one freely rotating presser roll, and then molded.

It is preferable that the cylindrical mold used in the present invention can be divided into at least two parts along the direction of the rotation axis, and the outside can be closed with bolts, and the cross section is usually a circle, an ellipse, a polygon, or any of these shapes. It is partially missing.

The molding material may be metal, wood, plastic, stone, etc., but metal is 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, taking into account 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 is fixed and the bran itself is 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 rotation speed at that time is 2 of gravity
A speed is selected that produces a centrifugal force less than twice that of gravity, preferably less than 1.2 times that of gravity, optimally a centrifugal force that is less than 1.2 times that of gravity.

Generally, the centrifugal force on the wall of a rotating body is F=mγω2
It is determined by In this case, F is the centrifugal force, m is the unit force, γ is the inner diameter of the rotating body, and ω is the angular velocity. Suppose that a cylindrical shape with an inner diameter of 2 m is rotated at a speed of 60 revolutions/minute to produce FRP.
When making a cylindrical carved object, the centrifugal force acting on a unit of 1 cm3 of the molded object is 7.0, assuming the specific gravity of the molding material is 1.8.
9g・cm/s2, whereas the gravity is F=mα
...(Note: α is acceleration), calculated as 1.8g・cm
/s2, so it is about 4 times the force of gravity. in this case,
For the centrifugal force to be twice the gravity, the rotation speed must be 30 revolutions/minute.
The circumferential speed is about 188 mm/min. According to experiments conducted by the present inventors, in order to prevent the supplied molding material from falling from the mold body in the general centrifugal molding method, a centrifugal force of more than twice the gravity, preferably more than four times the gravity, is required. is necessary, and 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 body of the present invention has a speed of 1 to 30 revolutions per minute, preferably 1 to 30 revolutions per minute, although it is not necessarily accurate because it varies depending on the inner diameter.
It is rotated at a rotational speed of ~18 revolutions/min, more preferably from 1 to 15 revolutions/degree of rotation, or at a circumferential speed of 0.5 to 300 m/min.

Examples of the fiber reinforcing material used in the present invention include known fiber reinforcing materials such as glass fiber, carbon fiber, and aramid fiber (manufactured by DuPont, Kepler fiber), with glass fiber being particularly preferred. Such reinforcing materials may be in the form of mats, ropings, chopped rovings cut into appropriate lengths, etc., and it is also possible to use a combination thereof. In addition, the amount of reinforcing material used in the present invention is usually 10% in the molded product.
A suitable amount is 80% by weight of grass, preferably 15-60% by weight, more preferably 20-50% 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 degradation accelerators may be supplied onto the fiber reinforcement on the inner surface of the mold separately from the resin or in a premixed manner.

In addition, the viscosity of the liquid thermosetting resin is important from the viewpoint of impregnation into the fiber reinforcing material, sagging phenomenon, etc. 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 the resin is usually selected appropriately from 0.5 to 20 poise/25°C (Brookfield viscosity), preferably 1.0 to 15 poise/25°C, and more preferably 2 to 10 poise. be done.

In the molding method of the present invention, an important step is the step of impregnating the fiber reinforcement with the liquid thermosetting resin by pressing the surface of the molding material with the weight of a freely rotating press roll.

This process involves impregnating and degassing a mold and a press roll, which have significantly different diameters, by forcing them to rotate at the same speed using a chain wheel or the like, as shown in JP-A-54-111577. It's completely different. That is, in the present invention, the mechanism is such that the suppression roll rotates freely as shown in FIG. At this time, it is preferable that the pressure roll be adjusted by at least one crank, a shaft that is movable in an appropriate width, or a combination thereof so that it can freely move forward and backward with an appropriate width. 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 weight of the suppression roll is used to sufficiently impregnate the fiber reinforcement with the liquid thermosetting resin in the molding material. Of course, it is okay to apply some load as long as it does not interfere with the free rotation of the pressure row, but if the load is too large or the weight of the roll itself becomes too much, the rotation speed of the mold will be slow. This is not preferable because the roll sinks into the molding material phase and the resin is squeezed out, resulting in a molded product with a low resin content. Furthermore, if the weight of the counterpressure suppression roll is small, impregnation of the resin 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 suppression 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 per roll length, preferably 5
A load of 0 to 400 g, more preferably 80 to 300 g,
In other words, one that applies pressing force to the surface of the molding material is suitable. 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 pressure 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 smaller than the inner diameter of the mold body, so that It only needs to be of a size that can be rotated at will, usually 5 to 40 cm in diameter.
is appropriate. In addition, it is better to have grooves on the outer peripheral surface of the roll that comes into contact with the molding material during pressing, and the shape of the grooves can be freely selected such as linear, spiral, or checkerboard in the roll axis direction, and the depth can also be freely selected. can be selected. Furthermore, the pressure roll may have a mesh-like net coated on its outer peripheral 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. It's okay to have one. Note that the inside of the roll may or may not be empty.

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 suppression roll, a molding material supplying part, etc. therein is connected to a cantilevered beam body B. A device is used that can move back and forth along the Alternatively, as shown in FIG. 3, the molding material supply part and the suppression roll are mounted so that part (2) is fixed without moving along the cantilevered image body B, and the molding die body A is rotated and at the same time 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 forming progresses.

It is supplied onto the treated material. After that, the pressing 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.

As the molding progresses, the mold body A or the reciprocating sliding body C moves to form a molded product, and after the liquid thermosetting resin is cured, a cylindrical article is produced. Thereafter, the bolts 2 and 3 are removed from tightening the mold body A, the mold body A is opened in half, and the cylindrical molded product is taken out.

According to the manufacturing method of the present invention, the obtained cylindrical molded product is made of FRP
By supplying plastic foam, resin concrete, etc., it is also possible to mold multi-layered cylindrical molded products such as two-layered or three-layered (Sanderman-style).

The cylindrical molded product obtained by the present invention has excellent strength because there is no uneven resin impregnation and the fiber reinforcing material is uniformly dispersed, and it can be used as a cylindrical container such as a tank, septic tank, or silo. can.

EXAMPLE Using a mold having an inner diameter of 2 m and a length of 6 m, a cylindrical FRP molded product was obtained using the manufacturing apparatus shown in FIGS. 1, 2, 4, and 5.

First, glass roving SP-3 (manufactured by Asahi Fiberglass Co., Ltd.) was cut into a length of 50 mm and weighed 4.5 kg on the surface of an iron mold rotating at a speed of 6 rotations/min (peripheral speed 53 m/min).
/min, and then an unsaturated polyester resin liquid (viscosity 6voices/25°C) containing 0.4% by weight of 6% by weight cobalt naphthenate (manufactured by Dainippon Ink Chemical Co., Ltd.) as a curing accelerator ( Polylite FG-104, manufactured by Dainippon Ink Chemical Co., Ltd.) and 55% by weight MEKPO as a catalyst.
An unsaturated polyester resin liquid (same as above) with a viscosity of 5 voids/25°C containing 1.5% by weight of (manufactured by NOF Corporation) was prepared separately, and each was passed through a 2-inch diameter conduit using a pump to give 5 kg/ It was fed onto the glass fiber at a rate of 100 min.

After that, length 50cm, diameter 15cm, weight 11.5
kg, and was pressed using a stainless steel pressing roll provided with grooves in the circumferential direction. At that time, the suppression roll is approximately 10c
Three press rolls were used with a roll interval of m, and the pressing force due to the weight of each press roll was about 230 g/cm.

In addition, the reciprocating sliding body to which the glass fiber, resin, etc. supply section and press roll are attached is 30 cm/30 cm along the mold rotation axis.
Moved at a speed of 1 minute.

The obtained cylindrical molded product has a length of 6 m, a diameter of 2.8 m, and a wall thickness of 8 m.
It was mm. Samples were cut out from this material in the axial and circumferential directions, and the strength was measured. The results are shown in Table-1. In addition, the void ratio of the molded product was also measured and is shown in Table 2.

Comparative Example 1 A centrifugal molding machine (hull) having a rotary mold with an inner diameter of 2 m and a length of 4 m.

Using Toman V-1.8-2.5-100 type),
The mold rotation speed was 90 revolutions/min, the circumferential speed was 565.2 m/min, and the same resin liquid and glass fiber supply rates as in the example were set at 22 kg/min and 9.8 kg/min, respectively, to form a mold with a wall thickness of 8 mm.
A cylindrical FRP molded product having a length of 4 m was obtained. Tests were conducted in the same manner as in Examples, and the results are shown in Table 1.

Comparative Example 2 An FRP cylindrical molded product was obtained using the same apparatus as in Example except that the press roll was changed to rotate in synchronization with the mold.

The conditions such as the mold rotation speed, the type of resin liquid and glass fiber, and the supply lid were the same as in the examples, but during molding, the molding material became lumpy at the press roll, and the roll was frequently separated from the molding material. Ta. For this reason, the efficiency was very low, and it took a lot of time to produce a molded product similar to that of the example.

Table 1 shows the physical properties of the molded product obtained. In addition, the void ratio of this molded product was measured and is shown in Table 2.

In Test Example Example and Comparative Example 2, the amount of resin and glass fiber supplied was adjusted so that each wall thickness was 3 mm, diameter was 2 m, and length was 3 m.
A cylindrical FRP molded article was molded. The front and back of these molded products were covered with FRP to prevent water leakage, and tap water was allowed to flow in. Tap water was then introduced to increase the water pressure and tested for water leaks. The results are shown in Table-3.

[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. FIG.
The figure is a side view of the device in Figure 1, Figure 3 is a molding material supply section,
FIG. 4 is a front view of a longitudinal cross-section of a molding device in which the mold body can move without the suppression rolls etc. moving; FIG. 4 is a front view of a portion where the suppression rolls are attached; and FIG. FIG. Note A: Molding mold body, B: Cantilever beam body C: Reciprocating sliding body, D: Fiber reinforcing material supply device E: Liquid thermosetting resin supply device F. ...Press roll, G...Mold body mounting section H...For mounting of molding material supply part and suppression roll, I...Rail, 1...Threaded part, 2...Tightening bolt 3 ...Tightening bolt, 4...Motor 5...Roller, 6.・・・
・Support 7...Fiber reinforced material receiving port, 8...Reinforcing material cutter 9...Fiber reinforced material falling port, 10...Mold inner surface 11...
・Mold rotation motor, 12...Mold rotation reducer 13...
・Mold movement motor, 14...Mold movement reducer 15・
...Self-propelled motor control panel, 16...Bearing 1
7... Form gear for traverse, 18... Reinforcement cutter drive motor 19... Resin supply nozzle 20
...Air cylinder 21...Arm 22...
Resin press roller for cutting reinforcing material, 23...Fiber reinforced material 24...Iron press roller for preventing the reinforcing material from coming off 25...Air cylinder for cutting reinforcing material 26...For cutting reinforcing material Rotating pulley 27...Motor 28...Resin supply nozzle 29.
...Crank 30...Press roll bearing 31...Press roll shaft patent applicant: Dainippon Ink & Chemicals Co., Ltd. Meisha:
Yamamoto Industries Co., Ltd. -26-

Claims (1)

[Claims] A fibrous 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 less than twice the force of gravity, and the surface of the material made of the reinforcing material and resin is freely shaped. 1. A method for producing a cylindrical molded article, which comprises pressing with the weight of at least one rotating press roll to sufficiently impregnate a reinforcing material with resin and molding the reinforcing material.