JP2007062338A - Shaping method of tubular member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of integrally shaping a tubular member (a composite tube) having a tube with a small diameter on the inner wall of a tube with a large diameter, which is used for a complicated and advanced robot arm and the like. <P>SOLUTION: The shaping method of the tubular member comprises steps for placing a fiber-reinforced prepreg sheet along the inner surface of a cavity of a tubular mold, arranging a core material the outer periphery of which is covered with a prepreg on the inner surface of the prepreg sheet, applying a rigid foaming material on the core material to fill a space between the core material and the inner surface of the prepreg sheet with, inserting an expandable bag in the cavity of the tubular mold, then making the prepreg tightly contact with the mold for curing by expanding the expandable bag in the cavity and heating, and pulling out the core material after curing the prepreg. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a tubular member made of fiber reinforced resin (FRP), and more particularly to a method of integrally forming a tubular member having a tube having a smaller diameter than the tube on the inner wall of a large diameter tube.

In general, a tubular body made of FRP is heated in a state where a fiber reinforced prepreg is wrapped around a mandrel and heated and cured, and a prepreg laid on the inner surface of a cylindrical mold is pressed from the inside of the mold using an expansion bag. Manufactured by an internal pressure molding method for curing. However, for example, it is difficult to integrally form a tubular member used for a robot arm or the like in which a tube having a diameter smaller than the inner diameter of the tubular body is arranged on the tubular body wall.

A robot arm, for example, a robot arm that attaches or detaches a processed product such as a compact disk, attaches or detaches the product by vacuum suction using a vacuum pipe disposed in a hollow arm made of FRP. . Conventionally, a robot arm that performs such vacuum suction cannot be integrally formed with an arm main body and a vacuum pipe, and is manufactured by the following procedure. That is, after forming the hollow arm body by the internal pressure molding method, etc., the through holes are machined in two places, the fixed end side to be attached to the robot and the free end side where the work is performed, and a tube such as a vacuum tube is A vacuum pipe was formed inside the arm by passing it from one through hole to the other through hole.

A method of integrally forming a robot arm by an internal pressure forming method has also been proposed relatively recently (see Patent Documents 1 and 2). According to these methods, a composite tubular body having a small-diameter pipe can be integrally formed on the inner wall of the large-diameter pipe, so that there is an advantage that the manufacturing cost can be reduced. However, recently, as a robot arm, a plurality of small-diameter pipes are arranged on the inner wall of a large-diameter pipe, or a more complicated arrangement is required. The pressing tends to be insufficient, and further improvement of the molding method is desired.
JP 2005-111772 A JP 2005-111773 A

An object of the present invention is to provide a method for integrally forming a tubular member (composite tubular body) having a small-diameter pipe on the inner wall of a large-diameter pipe, which is used for a complex and advanced robot arm or the like.

The invention according to claim 1 of the present invention is a core in which a sheet-like fiber reinforced prepreg is laid along the cavity inner surface of a cylindrical mold, and the outer periphery of the sheet-like prepreg inner surface is covered with the prepreg. In addition to placing the material, a hard foam material is attached so as to cover the core material to fill the gap with the inner surface of the sheet-like prepreg, and then an expansion bag is inserted into the cavity of the cylindrical mold, A method for forming a tubular member comprising inflating an inflatable bag in a cavity and heating the inside of the mold so that the prepreg adheres to the mold and is cured, and the core material is extracted after the prepreg is cured.

A second aspect of the present invention is the method for forming a tubular member according to the first aspect, wherein a plurality of cores whose outer circumferences are covered with a prepreg are arranged.

The invention described in claim 3 is characterized in that a plurality of holes are perforated in a cylindrical mold, and a core material whose outer periphery is covered with a prepreg is stretched in the cavity through the holes. It is a shaping | molding method of the tubular member of Claim 1 or 2.

Invention of Claim 4 is a shaping | molding method of the tubular member of any one of Claims 1-3 whose hard foam material is hard foaming urethane.

The invention according to claim 5 is the method for forming a tubular member according to any one of claims 1 to 4, wherein the core material is made by pouring shirasukon rubber into a hollow silicon tube.

According to the present invention, a tubular member (composite tubular body) having a plurality of small diameter tubes on the inner wall of the large diameter tube, or a tubular member having small diameter tubes arranged in a complicated manner on the inner wall of the large diameter tube can be integrally formed. Therefore, when manufacturing a robot arm, since it is not necessary to perform machining after arm formation and to attach a vacuum pipe as in the prior art, the manufacturing cost can be reduced.

In addition to the sheet-like fiber reinforced prepreg that is usually used, the present inventor has placed a core material whose outer periphery is covered with a prepreg in a hollow cavity and performs internal pressure molding on the inner wall of the large-diameter pipe. A composite tubular body having a small diameter tube can be integrally molded, and at that time, a hard foam material is attached so as to cover the entire core material covered with this prepreg, and the gap between the inner surface of the sheet-like prepreg is filled. Thus, it has been found that a desired tubular member can be easily formed integrally.

In the present invention, a sheet-like fiber reinforced prepreg is laid along the inner surface of a cavity of a cylindrical mold, and one or more cores whose outer periphery is coated with the prepreg on the inner surface of the sheet-like prepreg. A hard foam material is attached so as to cover the core material coated with the prepreg, and a gap with the inner surface of the sheet-like prepreg is filled, and then an expansion bag is placed in the cavity of the cylindrical mold Insert. Thereafter, the inflatable bag is inflated in the cavity, and the inside of the mold is heated so that the entire prepreg is brought into close contact with the mold and cured. And after all the prepregs harden | cure, a core material is extracted. At that time, the inflatable bag may be removed at the same time. In some cases, the inflatable bag may be left in the cavity without being removed.

The cylindrical mold of the present invention is not particularly limited in the shape of the mold, but typically, it is composed of an upper mold and a lower mold that can form a tubular (hollow) FRP member by an internal pressure molding method. means. The internal pressure molding method is a known molding method, in which a molding material such as a prepreg is placed in a cavity of a cylindrical mold that is a molding die, and this is in close contact with the mold by applying pressure from the inside of the cylinder. It is the method of heat-hardening with. As a means of applying pressure, an inflatable bag (pressure bag) made of a flexible and heat-resistant material such as nylon or silicone rubber is used, and this is inserted and placed in the center of the molding material. In this method, the pressure medium is fed into the bag to expand the bag, and the molding material is pressed against the inner surface of the mold to perform heat molding.

In the present invention, a core whose outer periphery is coated with a prepreg is used. The prepreg used here may be the same sheet-like fiber reinforced prepreg as that laid on the inner surface of the mold cavity, or other prepreg, for example, a reinforcing fiber knitted in a tubular shape is impregnated with resin. It may be a prepreg. The core material may be anything as long as it is flexible enough to form a hollow pipe even when pressed during internal pressure molding, and can be easily extracted from the pipe after molding. For example, although there are plastic tubes and pipes, those in which shirasukon rubber is poured into a hollow silicon tube can be particularly preferably used.

In the present invention, for example, two or more core materials whose outer circumferences are coated with a prepreg are arranged and arranged on the inner surface of a sheet-like fiber-reinforced prepreg laid along the inner surface of the cavity of a cylindrical mold. . According to the knowledge of the present inventor, even if it is subjected to the internal pressure molding method as it is, it is difficult to sufficiently press the entire prepreg against the inner surface of the mold because the space shape in the cavity is complicated. . Moreover, even if the outer periphery is a single core material covered with prepreg, if the arrangement state is complicated, it is difficult to sufficiently press the entire prepreg against the inner surface of the mold. Therefore, in the present invention, a hard foam material is attached so as to cover the core material coated with the prepreg, and the gap with the inner surface of the sheet-like prepreg is filled. By performing such a device, the subsequent internal pressure molding can be performed very efficiently.

The hard foam used in the present invention is not particularly limited as long as it is foamed under curing conditions and has heat resistance. For example, a foamed bead is mixed with hard foamed urethane or epoxy resin, and a foaming ratio of about several to 10 times is preferably used. The amount to be attached is not particularly limited, but it may be an amount sufficient to fill the gap between the core material coated with the prepreg and between the core material and the inner surface of the sheet-like fiber-reinforced prepreg. It ’s fine.

A prepreg is a molded intermediate material in which a fiber reinforcing material is impregnated with a matrix resin such as a thermosetting resin or a thermoplastic resin to improve handling properties except for fluidity and adhesiveness. The sheet-like fiber reinforced prepreg used in the present invention is not particularly limited as long as it is a sheet-like one. For example, a prepreg using unidirectionally arranged fibers such as uniaxial woven fabric and multiaxial woven fabric, woven fabric, knitted fabric, and nonwoven fabric as reinforcing fibers is used.

In the present invention, the fiber reinforcing material and matrix resin used are not particularly limited. Examples of the fiber reinforcing material include carbon fiber, glass fiber, aramid fiber, boron fiber, and metal fiber, and carbon fiber is particularly preferable. Examples of the thermosetting resin include epoxy resins, unsaturated polyester resins, phenol resins, vinyl ester resins, cyanate ester resins, urethane acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins and cyanate ester resins. There are resins selected from prepolymerized resins. These can also be used as one type or a mixture of two or more types. Examples of thermoplastic resins include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, and polyamideimide. is there. Two or more of these resins may be used in combination.

Hereinafter, an embodiment of the present invention will be described in detail by taking as an example a method for manufacturing a robot arm (an example in which two small-diameter tubes are arranged). An example of a cylindrical split mold used for manufacturing the robot arm is shown in FIGS. FIG. 1 is a plan view of the upper mold 1, and FIG. 2 is a plan view of the lower mold 2. The upper mold 1 and the lower mold 2 are hollow cylinders that are gradually formed to be thinner from one end to the other end, and are bent at approximately 90 degrees at the center thereof. Both ends are closed. The lower mold 2 is formed with two pairs of through holes 3a, 3b, 4a, 4b. 1 and 2, 5 and 6 are the cavity inner surfaces of the upper mold 1 or the lower mold 2. Cross-sectional views taken along lines AA and BB in FIG. 2 are shown in FIGS. 3 and 4, respectively. As shown in FIGS. 3 and 4, each section of the split type is a quadrangle with rounded corners. 1, 2, and 3, reference numeral 13 denotes an attachment hole on the fixed end side of the robot arm.

Next, integral molding of the robot arm will be described with reference to FIG. 5 which is a cross-sectional view taken along the line CC of FIG. First, as shown in FIG. 5 (a), a sheet-like fiber reinforced prepreg 7a for arm formation is laid along the cavity inner surface 6 of the lower mold 2. As shown in FIG. On the other hand, two prepregs 8a and 8b in which carbon fibers knitted into a tubular shape are impregnated with a resin and round bar-shaped flexible cores 9a and 9b are inserted into two pieces (10a and 10b) as shown in FIG. As shown in (2), it is arranged on the prepreg 7a. Further, one end side and the other end side of the prepreg into which the core material has been inserted are respectively inserted into the through holes 3a, 3b and 4a, 4b formed in the lower mold 2 through the arm forming prepreg 7a (10a). Are inserted into 3a and 4a, and 10a is stretched in the cavity) (see FIG. 2).

Next, as shown in FIG. 5B, the hard foam material 11 is attached to fill the gap so as to cover the core materials 10a and 10b whose outer periphery is covered with the prepreg. Next, as shown in FIG. 5 (c), the inflatable bag 12 is set inside the cavity in which the prepreg 7a is laid, and the upper die in which a sheet-like fiber-reinforced prepreg 7b for arm formation is laid on the inner surface 5 1 is clamped to the lower mold 2, and the prepregs 7 a, 7 b, 8 a, 8 b and the hard foam material 11 are integrally molded by an internal pressure molding method.

The internal pressure molding is performed by filling the expansion bag 12 with a fluid such as gas or liquid in the state of FIG. When the expansion bag 12 is inflated, the prepregs 7a and 7b are pressurized from the inside of the mold toward the outside so that the prepreg can be brought into close contact with the inner surfaces 5 and 6 of the mold. In addition, the prepregs 8a and 8b into which the core members 9a and 9b are inserted are also pressed by the expansion bag 12, and are pressure-bonded to the prepreg 7a together with the hard foam material 11 to be integrated.

Thereafter, the pressurized prepreg is heated and cured. After the prepreg has hardened, the core materials 9a and 9b are removed from the prepregs 8a and 8b, so that two vacuum pipes connecting the 3a and 4a and 3b and 4b, respectively, which become the suction holes of the robot arm, are integrally formed. A robot arm as shown in (d) is obtained. In FIG. 5D, the inflatable bag 12 is not shown, but the inflatable bag may be taken out at the same time as the core material or may be left inside. Thereafter, the insertion port of the inflatable bag can be closed with a lid if necessary.

For the purpose of absorbing excess resin that has oozed out of the prepreg and improving the releasability when taking out the molded product, use a peel cloth, blazer cloth, etc., if necessary, between the prepreg and the expansion bag. Also good.

In the above example, the description has been made using two divided types of quadrilateral whose cross section is rounded at substantially rounded corners, but by making the shape of the cross section of the divided type arbitrary shape such as circular, elliptical, triangular, quadrilateral, etc. An arm having an arbitrary cross-sectional shape can be formed. Further, the division type division number is arbitrary. In the above example, the through hole is formed in the lower mold 2. However, the hole formed in the mold is not limited as long as the suction hole is formed in the obtained robot arm and does not have to penetrate the mold. Furthermore, the hole formed in the mold may be formed in the upper mold, or may be formed in the side surface of the mold.

The shape and cross-sectional area of the flexible core materials 10a and 10b perpendicular to the length direction are not particularly limited, but usually the cross-sectional area of the cross-section perpendicular to the length direction of the core material is about 1 to 4 cm2. It is preferable that

The shape of the inflatable bag 12 is not particularly limited, but is preferably a shape that matches the shape of the robot arm. Moreover, the material in particular of the expansion | swelling bag 12 is not restrict | limited, The well-known thing used by the internal pressure molding method can be used. The pressure applied to the prepreg when performing the internal pressure molding is preferably 0.05 to 1 MPa.

In the above example, the case where the robot arm is manufactured has been described. However, in the manufacture of the composite tubular body having the small diameter tube on the inner wall of the large diameter tube, it is not always necessary to use a flexible core material as the core material. Any core material can be used as long as it has rigidity enough to form a small-diameter tube during internal pressure molding and can be removed after molding. Further, depending on the use of the composite tubular body, the suction holes may not be formed by inserting both ends of the prepreg coated with the core material into the holes formed in the mold.

A prepreg (W-3101 / Q-112: manufactured by Toho Tenax Co., Ltd.) was laid on the inner surfaces of the upper mold 1 as shown in FIG. 1 and the lower mold 2 as shown in FIG. The mold has a width of 80 cm and a thickness of 30 cm at the AA line, a width of 40 cm and a thickness of 20 cm at the BB line, a curve length of the mold of 320 cm, a linear distance of 150 cm (curve distance of 160 cm) between the holes 3a and 4a, and a hole of 3b. A straight line having a straight line distance of 160 cm (curved distance of 170 cm) was used. Two wraps of prepreg (W-3101 / Q-112: manufactured by Toho Tenax Co., Ltd.) were laid around the core material (180 cm long, 1.5 cm diameter hollow silicon tube poured with Shirasukon rubber). It arrange | positioned on a prepreg and the both ends of two core materials were inserted in the through-holes 3a and 4a, 3b, and 4b, respectively. Then, rigid foamed urethane (Air Tight Foam ATF-001, manufactured by Air Tight Co., Ltd.) is injected and adhered between the core material in which the prepreg is wound around the two wires and between the prepreg laid therewith, and the gap is filled. did.

Thereafter, a nylon bag (WRIGHTLON # 7400: manufactured by AIRTECH) was inserted to clamp the upper mold 1 and the lower mold 2. Fill the bag with gas, heat and cure the prepreg for 2 hours at 120 ° C under a pressure of 0.5 MPa, remove the core material, connect through-holes, and form two pipe-like vacuum pipes on the inner wall Got the robot arm.

The present invention is suitable for integrally forming an FRP tubular member such as a robot arm having one or more vacuum pipes on the inner wall of a cylindrical arm.

It is a top view of the upper mold | type of the metal mold | die used for manufacture of the robot arm which is an example of this invention. It is a top view of the lower mold | type of the metal mold | die used for manufacture of the robot arm which is an example of this invention. It is sectional drawing in the AA line of a lower mold | type. It is sectional drawing in the BB line of a lower mold | type. It is a figure for demonstrating the manufacturing method of the robot arm which is an example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper mold | type 2 Lower mold | type 3a, 3b, 4a, 4b Through-hole 5, 6 Cavity inner surface 7a, 7b Sheet-like fiber-reinforced prepreg 10a, 10b Core material 11 outer periphery coat | covered with prepreg 11 Hard foam material 12 Expansion bag 13 Mounting hole on the fixed end side of the robot arm

Claims (5)

A sheet-like fiber reinforced prepreg is laid along the inner surface of the cavity of the cylindrical mold, and a core material whose outer periphery is covered with the prepreg is arranged on the inner surface of the sheet-shaped prepreg so as to cover the core material. A hard foam material is attached to the inner surface of the sheet-like prepreg to fill the gap between the inner surfaces of the sheet-like prepreg, and then the expansion bag is inserted into the cavity of the cylindrical mold, and then the expansion bag is inflated in the cavity and within the mold. A method for forming a tubular member, comprising: heating a prepreg so that the prepreg adheres to a mold and curing the prepreg, and extracting the core material after the prepreg is cured. The method for forming a tubular member according to claim 1, wherein a plurality of cores whose outer circumferences are coated with prepreg are arranged. The tubular body according to claim 1 or 2, wherein a plurality of holes are perforated in a cylindrical mold, and a core material whose outer periphery is covered with a prepreg is stretched in the cavity through the holes. A method for forming a member. The method for forming a tubular member according to any one of claims 1 to 3, wherein the hard foam material is hard foam urethane. The method for forming a tubular member according to any one of claims 1 to 4, wherein the core material is obtained by pouring shirasukon rubber into a hollow silicon tube.

Images