JP3344398B2 - Preform stitching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stitching a preform made of reinforcing fibers such as carbon fiber and glass fiber.

[0002]

2. Description of the Related Art Conventionally, FRP products which are conventionally used in many fields as hulls, vehicle outer plates, mechanical parts, etc. are lighter and have the same strength as metal, but have strength in the thickness direction. Particularly, there is a disadvantage that the interlayer peel strength and the interlayer shear strength are low.

That is, such an FRP product generally has a flat preform in which a woven fabric made of reinforcing fibers such as carbon, glass, ceramics or the like or a reinforcing fiber layer made of a unidirectional sheet is laminated, or a reinforcing fiber layer is made of I. A preform processed into a girder material such as a mold or a T-type, or a preform consisting of a reinforcing fiber layer processed into a cylindrical shape using a braiding device such as a sheet winder, a filament winder, a braider, etc., with epoxy resin etc. Although hardened, in any case, there is nothing to reinforce the reinforcing fiber layers constituting the preform, so that there is a disadvantage that the interlayer peel strength and the interlayer shear strength are low.

[0004] Therefore, conventionally, when the preform is formed, the reinforcing fiber layers of the preform are stitched by stitching the reinforcing fiber layers one by one using a stitch thread made of the same reinforcing fiber. Have been proposed.

[0005]

By the way, stitch yarns used for performing such stitching are:
Although the same type of reinforcing fiber as the reinforcing fiber constituting the preform is often used, the conventional reinforcing fiber is generally
Since the knot (bending) strength is weak and the hair is easily fluffed, many of them have high frictional resistance to the fiber reinforced layer constituting the preform.

For this reason, when stitching is performed using a conventional industrial sewing machine or the like, the stitch yarn is cut during the stitching, or a needle for holding the stitch yarn Y as shown in FIG. After the (sewing needle) 1 is pulled out from between the fiber reinforced layers s and s, the stitch thread Y may not be loosened and may remain on the surface of the preform P in a loop shape. There was a problem that it could not be performed.

The present invention has been devised in order to effectively solve such a problem, and an object of the present invention is to provide a novel preform stitching which can easily perform a stable stitching operation. It provides a method.

[0008]

In order to solve the above-mentioned problems, according to the present invention, two or more laminated reinforcing fiber layers are stitched with a stitch thread composed of an upper thread and a lower thread. In the method of stitching a preform, before passing the needle holding the upper thread through the reinforcing fiber layer, a through hole is previously formed in the reinforcing fiber layer, and then the needle is inserted into the through hole. Stitching.

As a result, the frictional resistance when inserting and penetrating the needle holding the upper thread into the reinforcing fiber layer side is greatly reduced, so that the cutting of the stitch thread and the remaining slack can be reliably avoided. .

More specifically, immediately before the needle holding the upper thread is penetrated through the reinforcing fiber layer, a guide pipe having an inner diameter larger than that of the needle is provided. After inserting and penetrating, then, after inserting the needle into the penetrating guide pipe and entanglement the upper thread and lower thread, and withdrawing the needle, the guide pipe is delayed with the needle withdrawing operation. The stitching is performed by pulling out from the reinforcing fiber.

According to a third aspect of the present invention, by using a guide pipe having a sharp insertion tip and a slit formed on a side surface thereof for passing the stitch yarn, Insertion and penetration of the guide pipe into the reinforcing fiber layer are facilitated, and sewing of the guide pipe into the reinforcing fiber layer during stitching can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a stitching apparatus used in the method of the present invention.

As shown in the figure, this stitching device is provided with a guide pipe 2 having upper and lower openings coaxially below a needle 1 holding an upper thread Y1 constituting a stitch thread Y. The basic structure is almost the same as a conventional industrial sewing machine.

First, the needle 1 has its upper end connected to and supported by the end of a first swing arm 4 via a first vertical rod 3, and with the swing of the first swing arm 4. It moves vertically together with the first vertical rod 3. The first swing arm 4 has a first plate cam 6.
A cam follower 5 that slides along is provided.
As the cam follower 5 moves up and down, the entire first swing arm 4 swings up and down about its pivot point R as an axis.

On the other hand, the guide pipe 2 is also connected and supported by the end of a second swing arm 9 via a bracket 7 and a second vertical rod 8 extending from the upper end side surface. As the arm 9 swings, it vertically moves up and down together with the second vertical rod 8. Further, the second swing arm 9 is also provided with a cam follower 11 that slides along the second plate cam 10, and the second swing arm 9 is moved in accordance with the vertical movement of the cam follower 11.
The whole swings up and down about the axis fulcrum R as an axis.

A first plate cam 6 and a second plate cam 10 for swinging the first swing arm 4 and the second swing arm 9 are provided.
Is connected to the electric motor 15 via the camshaft 12 and the gears 13 and 14, and is driven to rotate synchronously by the electric motor 15.

The inner diameter of the guide pipe 2 is slightly larger than the outer diameter of the needle 1 so that the needle 1 holding the upper thread Y1 can be smoothly inserted and removed. I have. Further, the guide pipe 2 is formed so that the insertion end thereof is sharply cut obliquely from a bamboo tube, and has low resistance to insertion and penetration of the preform or the like made of the reinforcing fiber layers s, s. , So that it can be smoothly inserted and penetrated. in addition,
A slit 16 extending in the vertical direction from the upper end to the lower end is formed on the side surface, so that the stitch yarn Y that moves up and down together with the needle 1 can pass up and down along the guide pipe 2.

In FIG. 1, reference numerals 17 and 17 denote the needle 1
And a spring for urging the guide pipe 2 in the upward direction.

Next, an example of a preform stitching method according to the present invention using the stitching apparatus having the above-described configuration will be described.

First, when stitching is performed on a preform P composed of two or more reinforcing fiber layers s, s as described above, the preform P is formed similarly to a conventional industrial sewing machine or the like. The needle 1 is lowered at regular intervals while feeding the reinforcing fiber layers s, s in one direction, and penetrates between the reinforcing fiber layers s, s. To perform stitching.

At this time, if ordinary stitching is performed without any modification as described above, the stitch yarn Y is inserted due to the frictional resistance between the stitch yarn Y and the reinforcing fiber layers s, s when inserting and removing the needle 1. May not be removed and may remain in a loop, or in the worst case, stitch thread Y
May be cut.

Therefore, in the stitching method of the present invention, first, as shown in FIGS. 2A and 2B, the needle 1 holding the upper thread Y1 is inserted between the reinforcing fiber layers s. Immediately before the penetration, the guide pipe 2 is inserted into the penetration position in advance of the movement of the needle 1 beforehand, and the fiber at the insertion / penetration position is pushed around as shown in FIG. Through hole h larger than the inner diameter of needle 1
Is formed.

Next, while maintaining this state, FIG.
As shown in (3), the needle 1 is inserted into and penetrated into the guide pipe 2, and in this state, the upper thread Y1 held by the needle 1 is hooked by a not-shown stapler to form a loop while forming a loop. Thread Y supplied from
2 through the loop and entangle. by this,
The needle 1 is smoothly inserted and penetrated into the through hole h, and the upper thread Y1 held by the needle 1 does not directly contact the through hole h during insertion and penetration, so that little frictional resistance is generated. Therefore, even when a reinforcing fiber having a low knot strength and easy to fluff is used as the stitch yarn Y, it is possible to reliably avoid the disadvantage that the reinforcing fiber is cut during the stitching.

Thereafter, the upper thread Y1 and the lower thread Y
2 are engaged with each other, as shown in FIG. 2 (4), while the guide pipe 2 is kept penetrating as it is and only the needle 1 is raised, the upper thread is moved by a loosening lever (not shown) or the like. Raise Y1. Then, upper thread Y
1 and the through-hole h are not in direct contact with each other, so that there is almost no frictional resistance, the loop is securely loosened, and the upper thread Y1 and the lower thread 2 maintain a predetermined tension. Intertwined with each other, stitching at that position is performed well.

Then, when the stitching at that position is completed in this way, the guide pipe 2 is raised vertically to remove it from between the reinforcing fiber layers s and s.
The reinforcing fiber layers s, s are sent out at a predetermined pitch, and the above-described stitching process is repeated again for each stitch, whereby the reinforcing fiber layers s, s are sequentially stitched.
As described above, the side surface of the guide pipe 2 includes
Since the slit 16 for passing the stitch yarn Y is formed, the guide pipe 2 is not sewn to the reinforcing fiber layers s, s by the stitch yarn Y. Therefore, the slit width may be a width that allows the stitch thread Y to sufficiently pass therethrough, and may be appropriately changed depending on the thickness of the stitch thread Y used.

As described above, the stitching method of the present invention
Since the guide pipe 2 is inserted in advance at the insertion and penetration of the needle 1 and the guide pipe 2 is pulled up after the sewing operation is completed, the stitch thread Y, especially the upper Yarn Y1
Stitching can be performed in a state where there is almost no friction between the stitch yarn Y and the reinforcing fiber layers s, s, and stitching can be performed in a state where the tension of the stitch yarn Y is always stable.

As a result, reinforcing fibers conventionally difficult to use as stitch yarns, such as carbon fibers having low knot strength, easy to fluff and high friction resistance, and ceramic fibers having excellent heat resistance but very brittle ( Good stitching can be achieved even when SiC) or the like is used.

The operation timing of the needle 1 and the guide pipe 2 can be easily adjusted by changing the shapes of the first and second plate cams 6 and 10 that move the cam followers 5 and 11 up and down. Can be. That is, as shown in FIG. 4, the descent time of the guide pipe 2 by the second plate cam 10 for controlling the guide pipe 2 is longer than the descent time of the needle 1 by the first plate cam 6 for controlling the needle 1 side. As described above, the lowering of the guide pipe 2 can be performed before the lowering of the needle 1 as described above, and the raising of the guide pipe 2 can be performed later than the raising of the needle 1.

Further, in the present embodiment, an example has been described in which stitching is performed on a preform P made of a reinforcing fiber, but the method of the present invention can be applied to stitching other than the present embodiment. For example, the method of the present invention can be applied as it is to stitching a stitching thread that is thin and easy to cut, or when stitching a thick cloth or a rubber sheet with a large needle insertion / penetration frictional resistance. .

[0031]

In summary, according to the present invention, when stitching a preform comprising a fiber reinforced layer,
Stitching can be performed continuously while reliably reducing the frictional resistance between the stitch yarn and the reinforcing fiber layer. Therefore, even if a stitch yarn made of a reinforcing fiber having a low knot strength and a high frictional resistance is used, it is possible to perform a good stitching operation without cutting or loosening, and it is possible to efficiently perform the reinforcing fiber layer of the preform. Can be reinforced well. As a result, it is possible to exhibit excellent effects such as greatly contributing to the improvement in productivity of FRP products having excellent delamination strength and interlaminar shear strength.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a basic structure of a stitching device used in the method of the present invention.

FIG. 2 is a process chart showing one embodiment of a stitching method according to the present invention.

FIG. 3 is a conceptual diagram showing a state in which a guide pipe according to the present invention is inserted into and penetrates a fiber reinforced layer.

FIG. 4 is an explanatory diagram showing an example of operation timing of a plate cam for operating a needle and a guide pipe according to the present invention.

FIG. 5 is a process chart showing a conventional stitching method of a preform made of a reinforcing fiber by an industrial sewing machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 needle 2 guide pipe 3 first vertical rod 4 first swing arm 5, 11 cam follower 6 first plate cam 7 bracket 8 second vertical rod 9 second swing arm 10 second plate cam 12 camshaft 13,14 Gear 15 Motor 16 Slit 17 Spring P Preform R Shaft fulcrum Y Stitch thread Y1 Upper thread Y2 Lower thread s Reinforcing fiber layer h Through hole

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B29B 11/16 B29B 15/08-15/14 C08J 5/04-5/10 C08J 5 /twenty four

Claims (3)

(57) [Claims] 1. A preform stitching method wherein two or more laminated reinforcing fiber layers are stitched together with a stitch thread consisting of an upper thread and a lower thread, wherein a needle holding the upper thread is attached to the reinforcing fiber layer. A method for stitching a preform, wherein a through hole is formed in the reinforcing fiber layer before penetration, and then the needle is inserted into the through hole for stitching. 2. A stitching method for a preform in which two or more laminated reinforcing fiber layers are sewn together with a stitch thread comprising an upper thread and a lower thread, wherein the needle holding the upper thread is attached to the reinforcing fiber layer. Just before letting it penetrate,
After inserting and penetrating a guide pipe having an inner diameter larger than that of the needle, after inserting the needle into the penetrated guide pipe and tangling the upper and lower threads, and then pulling out the needle, A stitching method for a preform, wherein the guide pipe is pulled out from the reinforcing fiber and stitched after the needle is pulled out. 3. The guide pipe according to claim 2, wherein an insertion tip is sharpened and a slit is formed on a side surface of the guide pipe to allow the stitch thread to pass therethrough. Preform stitching method.