CN100447325C - Method for producing fiber formed body, fiber formed body produced by the method, and fiber mat manufacturing machine used in the method - Google Patents

Abstract

A fiber mixture including coarse fibers and fine fibers is prefabricated by a method of manufacturing a fiber forming body to form a fiber mat. The mixed fibers are supplied onto the outer peripheral surface of a roll. As the roller rotates, the mixed fibers are released from the roller and thrown towards a fiber receiving surface. A fiber mat is formed on the fiber receiving surface with a low density layer adjacent the fiber receiving surface and a high density layer on top of the low density layer. Coarse fibers mainly form low-density layers, while fine fibers mainly form high-density layers. The first and second fiber mats are laminated to each other such that their low density layers are opposite each other.

Description

Method for producing fiber formed body, fiber formed body produced by the method, and fiber mat manufacturing machine used in the method

This application claims priority from Japanese Patent Application No. 2003-142008, the contents of which are incorporated herein by reference.

technical field

The present application relates to a fiber-formed body comprising a low-density layer preformed mainly from coarse fibers and embedded between high-density layers mainly made up of fine fibers. The invention also relates to a method for producing such a fiber shaped body.

Background technique

Japanese Laid-Open Patent Publication No. 6-200460 discloses a known fiber shaped body and a method of manufacturing the shaped body. The known fiber-formed body of this publication is shown schematically in Fig. 5, and is marked with the symbol "A". The fiber forming body "A" includes a low-density core layer 51 and upper and lower high-density layers 53 , 55 disposed on the top and bottom surfaces of the core layer 51 . The core layer 51 is mainly coarsely made of coarse inorganic fibers (thickness: 15 micrometers). The surface layers 53 and 55 are densely made mainly of fine inorganic fibers (thickness 10 microns).

To manufacture the fiber formed body "A", different machines separately form the core layer 51 , the top surface layer 53 and the bottom surface layer 55 . The layers are then laminated to each other and punched with needles to form a fiber mat. Subsequently, the upper and lower sides of the fiber mat are laminated with a resin film. The resin film is heated. Finally, the fiber mat with the heated resin film is punched with a heat press, and the fibers of the mat are bonded to each other by the molten resin to obtain a fiber molded body.

However, this known method for manufacturing the fiber forming body "A" requires the core layer 51 and the top and bottom surface layers 53, 55 to be formed separately. This increases the cost of the entire machine. In addition, since the layers 51, 53, 55 have to be bonded together after they have been laminated to each other, manufacturing efficiency is relatively low.

Contents of the invention

The object of the present invention is to provide an improved technique which makes it possible to reduce the machine costs for producing fiber shaped bodies and which makes it possible to increase the corresponding production efficiency of fiber shaped bodies.

According to one aspect of the present subject matter, a method for making a fiber forming body is disclosed. The fiber formed body includes a low-density layer mainly coarsely formed of coarse fibers embedded between upper and lower high-density layers, the high-density layer mainly densely composed of thin fibers. The method comprises the following steps (a) to (f):

(a) Prefabrication of a fiber mixture comprising coarse fibers and fine fibers. The average weight of fine fibers is lighter than the average weight of coarse fibers.

(b) Making a first and second fiber mat from mixed fibers. Each of the first and second fiber mats includes a low density layer composed primarily of coarse fibers and a high density layer densely composed primarily of fine fibers. Both the first and second fiber mats are made by the following sub-steps (b1) and (b2):

(b1) The mixed fiber is supplied onto the outer peripheral surface of a roll. The roller is configured to temporarily hold the mixed fibers on the outer peripheral surface.

(b2) Rotating the roller so that the mixed fiber rotates together with the roller, and releasing the mixed fiber from the roller so that the mixed fiber is thrown toward a flat fiber receiving surface due to the rotational force of the roller. The released fibers form a fiber mat on the flat fiber receiving surface.

(c) Inverting one of the first and second fiber mats.

(d) Laying the first and second fibrous mats so that the low density layers of each fibrous mat face each other.

(e) Combining two fiber mats superimposed on each other.

(f) Bonding the fibers together.

According to this method, the rotational force of the roller throws the mixed fibers off the outer peripheral surface of the roller causing it to fall on a flat fiber receiving surface. Thus, coarse fibers can reach the fiber-receiving surface before fine fibers reach the fiber-receiving surface. Therefore, a low-density layer mainly comprising coarse fibers is first formed on the fiber-receiving face. Then, a high-density layer mainly comprising fine fibers is formed on the low-density layer via an intermediate layer, called a transition layer. Thus, a single processing step can form a fiber mat having a low density layer and a high density layer on a fiber receiving surface.

The first fiber mat and the second fiber mat can be obtained by the following steps. Flip one of the two pads over. The two pads are then laid on top of each other so that the low density layer is directly opposite. The first fiber mat and the second fiber mat are then bonded to each other. The fibers of the two mats are bonded together to form a composite fiber forming material having upper and lower high density layers and a low density layer embedded between the high density layers.

According to this method, a fiber mat having a low density layer and a high density layer can be formed in a single processing step. Therefore, the number of machines required to manufacture a fiber formed body can be reduced as compared with the known method requiring separate machines to form a low density layer, an upper high density layer and a lower high density layer. In addition, since the fiber mat can be constructed from a single processing step, the manufacturing efficiency of the fiber mat can be improved.

In another aspect of the subject matter, the same rolls and the same fiber receiving surface can be used to form the first and second fiber mats.

In another aspect of the subject matter, different rolls can be used to form the first and second fiber mats. In this case, step (c) may comprise positioning the first fiber mat on a surface. The first fiber mat is oriented such that the high density layer is in contact with the surface and the low density layer is exposed to the surrounding environment, for example away from the surface in an upward direction. The second fiber mat is positioned such that the low density layer of the second fiber mat is directly opposite the low density layer of the first fiber mat. A second fiber mat is placed on the first fiber mat.

Thus, the second fiber mat can be placed directly on the first fiber mat to form a fiber forming body. Therefore, the production efficiency of the fiber formed body can be further improved.

In another aspect of the subject matter, the first and second fiber mats are formed on different fiber receiving surfaces. The step of inverting the first fiber mat (step (c)) also includes automatically inverting and conveying the first fiber mat to a moving surface located below the roll used to form the second fiber mat. The second fiber mat is formed directly on the inverted first fiber mat. The low density layers of each pad are adjacent to each other.

In yet another aspect of the subject matter, the fine fibers include inorganic fibers and thermoplastic resin fibers. Thermoplastic resin fibers can serve as a medium for bonding other fibers together. More specifically, the thermoplastic resin fibers can be melted by heat to bind the inorganic fibers together and/or to bind the inorganic fibers to the coarse fibers.

Preferably, the thermoplastic resin fibers include polypropylene fibers, and the diameter of the polypropylene fibers can be selected between 15 microns and 17 microns.

Preferably, the inorganic fibers comprise carbon fibers having a diameter of less than 10 microns.

Preferably, the crude fiber includes sisal fiber, and the diameter of the sisal fiber can be selected between 80 microns and 250 microns.

In another aspect of the subject matter, the disclosed fibrous forming body includes a low density layer coarsely formed primarily of coarse fibers and first and second high density layers densely formed primarily of thin fibers. A low density layer is embedded between the first and second high density layers. The diameter of the coarse fibers can be selected between 80 microns and 250 microns. Preferably, the crude fibers comprise sisal fibres.

Since the diameter of the thick fiber is equal to or larger than 80 micrometers, the necessary thickness and rigidity of the fiber formed body can be ensured. However, since the thick fibers have a diameter of 250 micrometers or less, the deformability of the low-density layer does not decrease to maintain the formability of the fiber-formed body.

Preferably, the fine fibers include inorganic fibers and thermoplastic resin fibers. Thermoplastic resin fibers can serve as a medium for bonding other fibers together. For example, the thermoplastic resin fiber can be polypropylene fiber, and the diameter of the polypropylene fiber can be selected between 15 microns and 17 microns.

Preferably, the inorganic fibers comprise carbon fibers having a diameter of less than 10 microns.

In yet another aspect of the present subject matter, the disclosed fiber mat making machine includes a rotating roll having an outer peripheral surface and a fiber retaining device that retains fibers on the outer peripheral surface within a predetermined angle of rotation. A feeder is used to feed a mixture of coarse fibers and fine fibers onto the outer peripheral surface of the roll. A conveyor is positioned below the roller and is adapted to receive and convey fibers thrown off the roller as the roller rotates. A fibrous mat comprising a high density layer consisting primarily of fine fibers and a low density layer consisting primarily of coarse fibers is formed on a conveyor.

Thus, a fiber mat having a high density layer and a low density layer can be produced in a single processing step. Thereby, the number of machines required to manufacture the fiber mat can be reduced. A single processing step results in reduced manufacturing costs and increased manufacturing efficiency. Thus, a single machine can advantageously be used to produce a fiber forming body having a low density layer embedded between a first and a second high density layer.

Preferably, the fiber retaining means comprises a plurality of needles extending outwardly from the outer circumference of the roll.

The fiber holding device may further include auxiliary rollers disposed along the outer peripheral surface of the roller, each auxiliary roller being spaced a predetermined distance from the outer peripheral surface of the roller.

Preferably, the conveyor comprises a conveyor belt driven at a constant speed. For a given roll rotation speed, the speed is approximately proportional to the amount of material per unit length and/or the thickness of the resulting fiber mat.

In another aspect of the present subject matter, the disclosed fiber mat making machine can include first and second rotating rolls. Each rotating roller has an outer peripheral surface. The outer peripheral surface has a means for retaining the fibers on the outer peripheral surface within a predetermined angle of rotation. The first and second feeders are used to supply a mixture of coarse fibers and fine fibers onto the outer peripheral surfaces of the first and second rolls, respectively. A first conveyor is disposed below the first roller and is adapted to receive and transport fibers. The fibers are thrown off said first roller as the first roller rotates to form a first fiber mat on the first conveyor, the first fiber mat comprising a high density layer mainly composed of fine fibers and a mainly A low-density layer of coarse fibers. A second conveyor is positioned below the first conveyor and the second rollers. The second conveyor is used to receive and convey the first fiber mat in an inverted position. The second conveyor is also used to receive fibers which are thrown off the second roller as the second roller rotates, thereby forming a second fiber mat on top of the first fiber mat, said second fiber mat comprising a main A second high-density layer composed of fine fibers and a second low-density layer mainly composed of coarse fibers. The second fiber mat is configured such that the first low density layer of the first fiber mat is directly opposite the second low density layer of the second fiber mat.

With this structure, the fiber mat manufacturing machine can continuously manufacture a composite mat composed of the first and second fiber mats. The composite mat has upper and lower outer high density layers, and an inner low density layer embedded between the outer high density layers. Thus, the composite mat can be advantageously used in a manufacturing process such as press forming to produce a product having a desired structural form, for example suitable for a vehicle roofing material.

Preferably, the fiber retaining means of the first and second rolls comprise a plurality of needles extending outwardly from the outer peripheral surfaces of the respective rolls.

Preferably, the fiber holding devices of the first and second rollers further include a plurality of auxiliary rollers arranged along the outer peripheral surface of each corresponding roller. Each auxiliary roller is spaced a predetermined distance from the outer peripheral surface of each corresponding roller.

Preferably, the first and second conveyors each comprise a conveyor belt driven at a constant speed.

Preferably, the first and second conveyors are driven in opposite directions to each other. Therefore, when the first fiber mat is transferred to the second conveyor, the first fiber mat can be turned over smoothly.

Description of drawings

FIG. 1(A) is a schematic side view of a first typical fiber mat manufacturing machine showing a first typical method for making a fiber mat suitable for forming a fiber forming body; and

Fig. 1 (B) is the vertical sectional schematic view of the fiber mat taken along section BB; And

2(A) and 2(B) are schematic vertical sectional views showing an initial process of manufacturing a fiber formed body by laminating first and second fiber mats to each other; and

3(A) to 3(C) are schematic diagrams showing subsequent processes for manufacturing a fiber formed body; and

FIG. 3(D) is a schematic diagram showing a process of making a roof material from a fiber molded body; and

FIG. 4(A) is a schematic side view of a second typical fiber mat making machine showing a second typical method for making a fiber mat suitable for forming a fiber forming body; and

4(B) and 4(C) are schematic vertical cross-sectional views of a first fiber mat taken along section BB and a comparison mat made by the second exemplary method along section CC; and

Fig. 5 is a schematic vertical sectional view of a known fiber forming body.

Detailed ways

The additional features and subject matter that will be disclosed above and below can be used alone or in combination with other features and subject matters to provide improved methods and machines for manufacturing fiber forming bodies, and fiber forming bodies made by such methods and machines . Examples of the invention will now be described with reference to the accompanying drawings, which examples employ numerous additional features and subject matter both individually and in combination. The detailed description merely teaches those skilled in the art further details for implementing preferred aspects of the subject matter, and does not limit the scope of the invention. Only the claims define the scope of the invention claimed. Therefore, combinations of features and steps disclosed in the following detailed description are not necessary to practice the invention in the broadest sense, but are instead provided merely to particularly illustrate examples of the invention. Furthermore, various features of the examples and dependent claims may be combined in ways not specifically listed to form additional effective embodiments of the subject matter.

(first embodiment)

A first typical fiber formed body and a first typical method of manufacturing the same will now be described with reference to FIGS. 1 to 4. FIG. A first typical fiber molding is implemented as a base material which can be used as a roof material. Figure 1(A) shows a first exemplary machine 30 for making fiber mats. 2(A) and 2(B) show steps of manufacturing a fiber mat that becomes a fiber forming body material. 3(A) to 3(D) show the steps of manufacturing the roof member.

Please refer to FIG. 2(B), a fiber forming body 10 is made of two fiber mats 20 . Each fiber mat 20 is composed of about 25% by weight natural fibers, about 25% by weight inorganic fibers, and about 50% by weight thermoplastic fibers. The natural fibers are preferably sisal fibers having a thickness of about 150 to 160 microns and a length of about 150 mm. The average weight of sisal fiber is about 0.082 grams.

The inorganic fibers are preferably carbon fibers having a thickness (diameter) of about 7 microns and a length of about 100 mm. The average weight of carbon fiber is about 0.0001 grams.

Thermoplastic fibers are added to bind the inorganic fibers to each other and the natural fibers to the inorganic fibers. Preferably, the thermoplastic fibers may be polypropylene fibers having a thickness (diameter) of about 15 to 17 microns and a length of about 64 mm. The average weight of polypropylene fibers is about 0.00002 grams.

As shown in Fig. 1 (B), 2 (A) and 2 (B), a high-density layer 22 is positioned at the top side (upper side) of each fiber mat 20, and is mainly made up of thin and light fiber densely, for example Carbon and thermoplastic fibers. A low density layer 24 is located on the underside (underside) of each fiber mat 20 and is predominately coarse and heavy fibers, such as sisal fibers. The high-density layer 22 and the low-density layer 24 are bonded to each other by means of an intermediate layer 23 . Intermediate layer 23 does not define a sharp edge, but has a density profile that varies between layers 22 and 24 . In summary, for this particular embodiment, the percentages of carbon fibers and thermoplastic fibers in the intermediate layer 23 increase in the direction towards the high density layer 22 . Conversely, the percentage of sisal fibers in the middle layer 23 increases in the direction towards the low density layer 24 .

Two fiber mats 20 can be used to form the fiber forming body 10 . The two fiber mats 20 are laminated to each other such that the low density layer 24 of one fiber mat 20 directly opposes the low density layer 24 of the other fiber mat 20 (as shown in FIGS. 2(A) and 2(B)). The fiber mat 20 is then perforated by a needle punch (not shown). The average surface density (mass per unit area) of the fiber mat 20 in the laminated state is preferably approximately selected within the range of 450 g/m ² to 600 g/m ² .

The machine 30 for making the fiber mat 20 will now be described. After the description of the machine 30, the steps of manufacturing the fiber formed body 10 composed of the fiber mat 20, and the steps of manufacturing the top surface material will be described. The roofing material can be used for automobiles, and can be composed of the fiber formed body 10 .

As shown in Fig. 1 (A), the machine 30 that is used to manufacture fiber mat 20 comprises a main roll 32, and this main roll is rotatably driven, and sisal fiber, carbon fiber and thermoplastic fiber (hereinafter collectively referred to as " fiber F ”) is temporarily carried or captured on the outer peripheral surface 34 of the main roller 32. Finally, the main roll 32 has a horizontal rotation axis and a plurality of needles 36 extending outward from an outer peripheral surface 34 for carrying fibers F. As shown in FIG.

A plurality of auxiliary rollers 38 are provided around the main roller 32 and are arranged along the outer peripheral surface 34 in the circumferential direction of the main roller. The auxiliary roll 38 plays a role of helping the main roll to keep the fiber F carried on the outer peripheral surface 34 of the main roll 32 . The auxiliary roller 38 has a rotation axis parallel to that of the main roller 32 . An outer peripheral surface 38 r of each auxiliary roller 38 is spaced a predetermined distance from the outer peripheral surface 34 of the main roller 32 . In addition, the auxiliary roller 38 may be rotationally driven in a direction opposite to that of the roller 32 so that the fibers F carried on the outer peripheral surface 34 of the main roller 32 smoothly pass through the space between the peripheral surface 34 and the auxiliary roller 38 .

As shown by the arrow in FIG. 1(A), the main roll 32 rotates in the counterclockwise direction, and applies a rotational force (the rotational force includes the centrifugal force and the inertial force of the fiber F) to the fiber F. As shown in FIG. A fiber feeder 35 is provided on the left and right sides of the main roll 32 . The feeding machine 35 includes a storage tank 35h and a feeding device 35f. Storage tank 35h is used to store a substantially homogeneous mixture of sisal fibres, carbon fibres, and thermoplastic fibres. The supply device 35f supplies the stored fibers F onto the outer peripheral surface 34 of the main roll 32 at a rate of supplying a predetermined volume of fibers per unit time.

A fiber conveyor 31 is configured as a conveyor belt and is arranged horizontally below the main roller 32 . The fiber conveyor 31 is driven so as to correspond to the rotation of the main roll 32 . The fiber conveyor 31 serves to receive the fibers F thrown down from the outer peripheral surface 34 of the main roller 32 by the rotational force of the main roller 32 (together with other forces). The fiber conveyor 31 is driven in a forward direction (seen in Figure 1(A) as a rightward direction) at a relatively constant speed. As a result, the fibers F are accumulated on the fiber conveyor 31 . The fibers F form a fiber layer of approximately uniform thickness. The driving speed of the conveyor 31 can be varied in order to adjust the thickness of the fiber layer.

Hereinafter, the steps of manufacturing the fiber mat 20 and the steps of manufacturing the fiber formed body 10 will be described in conjunction with the operation of the machine 30 .

The main roller 32 can be driven in a counterclockwise direction. The auxiliary roller 38 can be driven in a clockwise direction. The fiber conveyor 31 is driven so as to correspond to the rotation of the main roll 32 . Once the main roll 32, auxiliary roll 38 and conveyor 31 are all driven at their respective predetermined speeds, the fiber feeder 35 feeds fibers F onto the outer peripheral surface 34 of the main roll 32 at a speed of a predetermined volume per unit time.

The fibers F supplied onto the outer peripheral surface 34 of the main roll 32 are engaged and held by the needles 36 , and rotate substantially together with the main roll 32 . The auxiliary roller 38 disposed around and near the outer peripheral surface 34 of the main roller 32 can hold the fiber F near the outer peripheral surface 34 of the main roller 32 . Therefore, the fibers F are prevented from being thrown off the main roll 32 by the centrifugal force. When the fiber F carried on the outer peripheral surface 34 of the main roll 32 reaches the lower side of the main roll 32 without being constrained by another auxiliary roll 38, the rotational force (such as centrifugal force and inertial force) of the main roll 32 of the fiber F can move toward the fiber F. The conveyor 31 throws the fibers F downward.

Fibers F are formed by mixing coarse and heavy fibers such as sisal fibers with relatively thin and light fibers such as carbon and polypropylene fibers, as previously described. The rotational force of the main roll 32 on the fibers F causes the thick and heavy sisal fibers to be thrown off the main roll 32 earlier and thus reach the fiber conveyor before the thinner and lighter fibers such as carbon and polypropylene fibers 31.

As shown in FIG. 1(B), the result is that a coarsely woven or low-density layer 24 mainly comprising coarse and heavy sisal fibers is first formed on the conveyor 31 . A dense or high density layer 22 comprising mainly thin and light carbon fibers and polypropylene fibers is formed on top of a low density layer 24 . A transition intermediate layer 23 is formed at the edges of the low density and high density layers. A fiber mat 20 having a predetermined thickness is formed on a conveyor 31, and a low-density layer 24 is located on the lower side (as shown in FIG. 1(B)). Preferably, the speed of the conveyor is adjusted so that the fibrous mat 20 has an average surface density (mass per unit area) of about 450 g/ ^m2 to 600 g/ ^m2 .

Any two fiber mats 20 that will be made according to the above steps by the machine 30 are superimposed on each other so that the low-density layer 24 of one of the fiber mats 20 is directly opposite to the low-density layer 24 of the other fiber mat 20, as shown in Figure 2 (A ) and 2(B). The laminated fiber mats 20 are then punched with a needle punch (not shown in the drawings) to bond the fiber mats 20 to each other.

The perforated fiber mat 20 is then heated to the melting temperature of polypropylene fibers. As shown in FIG. 3(A), a skin material 26 is laminated over the top and bottom surfaces of the bonded fiber mat 20 by means of an adhesive film (not shown). A heat press 43 punches the bonded fiber mat 20 and skin material 26 as shown in FIGS. 3(A) and 3(B). The melted polypropylene fibers then impregnate all the carbon fibers of the high density layer 22 and all the sisal fibers of the low density layer 24 . The carbon fibers are bonded to each other and to the sisal fibers. Alternatively, the skin material 26 may be bonded to the corresponding high density layer 22 of the bonded fiber mat 20 by means of melted polypropylene fibers and an adhesive film.

As shown in FIG. 3(C), the pressure of the heat press 43 is then released. The bonded fiber mat 20 bonded with the skin material 26 is kept in a released state for a predetermined period of time, so that the fiber formed body 10 is obtained. During this time, the thickness of the bonded fibrous mat 20 recovers to some extent due to the restoring force exerted by the low density layer 24 . After the predetermined period of time, the final step for manufacturing the fiber formed body 10 can be completed.

As shown in FIG. 3(D), the fiber formed body 10 may be transferred to a cold press for final setting. In this example, the fiber formed body 10 is cold-pressed to have a structural form usable as a vehicle roof material.

The top surface material made from the fiber forming body 10 preferably has an average surface density (mass per unit area) of about 450 g/m ² to 600 g/m ² . This example may have a thickness of about 3.5 to 4.5 millimeters. This thickness is greater than typical thicknesses of conventional fiber forming bodies (eg, about 3 mm), which may have the same average surface density as the fiber forming body 10 . Whereas conventional fiber forming bodies have a uniform density throughout their thickness, fiber forming body 10 has several layers of different densities.

According to this typical method of manufacturing the fiber formed body 10, the fiber mat 20 including the low-density layer 24, the middle layer 23, and the high-density layer 22 can be manufactured by using a simple process and a single machine. The two fiber mats 20 are laminated so that their low-density layers 24 facing each other are assembled into the fiber formed body 10 . Compared to conventional methods where the core low density layer, the upper high density layer and the lower high density layer are typically machined individually, the number of machines for this typical method can be reduced to save associated machine and other costs. In addition, since the fiber mat 20 including a low-density layer 24, an intermediate layer 23 and a high-density layer 22 is manufactured in a single process, the manufacturing efficiency of the fiber formed body 10 is also improved compared with conventional methods.

In addition, since sisal fibers having a thickness of 150 μm or more are used as the main material of the low-density layer 24 , the low-density layer 24 can provide the necessary thickness and rigidity of the fiber formed body 10 . Additionally, due to the selected diameter of the sisal fibers being less than or equal to 160 microns, the low density layer 24 is relatively easy to deform, resulting in a relatively easy forming of the fiber forming body 10 . However, if the diameter of the sisal fibers is approximately or equal to 80 micrometers, the necessary thickness and rigidity of the fiber-formed body can still be preserved to some extent. In addition, if the diameter of the sisal fibers is selected to be less than or equal to 250 micrometers, the fiber forming body 10 is still somewhat deformable.

In addition, since this typical fiber-formed body 10 has a low-density layer 24 mainly composed of thick fibers, the thickness of the fiber-formed body 10 can be reduced compared to a conventional fiber-formed body having the same average surface density but having a uniform density throughout its thickness. The thickness is large. Therefore, it is necessary to increase the gap between the molds of the cold press 45 so that the roof material produced from the typical fiber formed body 10 by the cold press 45 has a relatively large thickness.

In addition, since the thickness of the roof material can be increased without affecting the average surface density, the rigidity of the roof material can be increased and the sound absorption characteristics of the roof material can be improved.

(the second typical embodiment)

Fig. 4(A) is a schematic diagram of a second typical fiber mat manufacturing machine 1 which can continuously form two fiber mats 20 so that they are automatically laminated to each other in the correct orientation.

The machine 1 comprises a first machine section 30a for making one of the two fiber mats 20 (hereinafter referred to as "the first fiber mat 20") and a fiber mat for making the other of the two fiber mats (hereinafter referred to as "the first fiber mat 20"). The second machine part 30b hereinafter referred to as "second fiber mat 20"). The basic construction of the first machine section 30a and the construction of the second machine section 30b are substantially the same as those of the first exemplary machine 30 previously described. Accordingly, in FIG. 4(A), the components of the first and second machine sections are the same as those of the first exemplary machine 30 and are labeled with the same reference numerals. A repeated description of these components is unnecessary.

The first machine part 30a differs from the first typical machine 30 in that the roller 32 of the first machine part 30a is rotatably driven in a clockwise direction in order to apply a rotational force to the fiber F1. Thus, the feeder 35 of the first machine part 30 a is located on the left side and upper side of the roller 32 .

The conveyor 31 is replaced with a first fiber conveyor 31a (hereinafter also referred to as "first conveyor 31a") and a second fiber conveyor 31b (hereinafter also referred to as "second conveyor 31b"), the first and The second fiber conveyor is configured as a horizontal conveyor belt. The first and second conveyors 31a and 31b are driven at their respective predetermined, relatively constant speeds.

The first conveyor 31a is disposed below the rollers 32 of the first machine section 30a. The fibers F1 cast down from the rollers 32 of the first machine section may be received by the first conveyor 31a to form a first fiber mat 20 . The first conveyor 31a is driven to convey the first fiber mat 20 in a rearward direction (leftward direction as seen in FIG. 4(A)).

The second machine part 30b is located in front of the first machine part 30a (viewed to the right in FIG. 4(A)), and has a main roller 32 driven counterclockwise, which can apply a rotational force in fiber.

The second conveyor 30b is located below the rollers 32 of the first conveyor 30a and the second conveyor 30b. The second conveyor 30b can receive the first fiber mat 20 conveyed in the opposite orientation from the first conveyor 30a. Additionally, the second conveyor 30b may receive fibers F2 cast down from the main roll 32 of the second machine section 30b. These fibers F2 form the second fiber mat 20 . The second fiber mat 20 is formed on top of the first fiber mat 20 . The second conveyor 30b conveys the bonded first and second fiber mats 20 in a forward direction (right as viewed in FIG. 4(A)).

In operation, fibers F1 are thrown down from the main roll 32 of the first machine section 30a and received by the previously described first conveyor 31a. Thus, the first fiber mat 20 can be formed on the first conveyor 31a with the low-density layer 24 on the lower side. The first fiber mat 20 can then be conveyed backwards (to the left as seen in FIG. 4(A)). At the rear (left) end of the first conveyor 31a, the first fiber mat 20 may be transferred onto a second conveyor 31b. Since the conveying direction of the second conveyor 31b is opposite to that of the first conveyor 31a, the first fiber mat 20 can be turned upside down when it is conveyed to the second conveyor 30b.

In other words, the first fiber mat 20 can be conveyed onto the second conveyor 31b with its high-density layer 22 on the lower side. Then, the second conveyor 31b advances the inverted first fiber mat 20 (rightward as viewed in FIG. 4(A) ). The first fiber mat 20 passes under the second machine section 30b at a relatively constant speed. The fibers F2 are cast down from the main roll 32 of the second machine section 30b and accumulated on the first fiber mat 20 so as to have a substantially uniform thickness. Thus, the second fiber mat 20 is arranged directly above the first fiber mat 20 and the low density layer 24 of the second fiber mat 20 is opposite the low density layer 24 of the first fiber mat 20 .

Then, the first and second fiber mats 20 superimposed on each other at the low density layer 24 are transferred to a needling machine (not shown in the figure) to be bonded together by needling. The steps after needling (necessary to manufacture the fiber formed body 10) are the same as the first exemplary embodiment.

In this way, according to the second exemplary embodiment, the first and second fiber mats 20 can be manufactured continuously and automatically laid on top of each other. Thereby, the manufacturing efficiency of the fiber formed body 10 can be further improved.

The invention is not limited to the above exemplary embodiments but can be varied in many ways. Although sisal fibers are used as the natural fibers forming the low density layer 24 in the exemplary embodiment above, other natural fibers such as kenaf, palm hemp, etc. may be used instead of sisal fibers.

In addition, although carbon fiber is used as the inorganic fiber forming the high-density layer, glass fiber, metal fiber, etc. may be used instead of carbon fiber.

In addition, although polypropylene fibers are used as thermoplastic fibers, paraffin resin fibers such as polyethylene, polybutene, etc., can also be used instead of polypropylene fibers.

Claims (16)

1. A method for manufacturing a fiber-formed body, wherein the fiber-formed body comprises a low-density layer mainly formed from crude fibers embedded between upper and lower high-density layers, the high-density layer Consisting mainly of fine fibers compactly, the method includes: (a) prefabricating a fiber mixture comprising coarse fibers and fine fibers, wherein the average weight of the fine fibers is less than the average weight of the coarse fibers; and (b) making a first and a second fiber mat from mixed fibers, wherein each fiber mat comprises a low density layer mainly coarsely formed of coarse fibers and a high density layer mainly densely formed of fine fibers, And wherein, each fiber mat is made by the following method: (b1) supplying the mixed fiber to the outer peripheral surface of a roller, wherein the roller is configured to temporarily hold the mixed fiber on the outer peripheral surface; and (b2) Rotate the roller so that the mixed fiber rotates with the roller, and release the mixed fiber from the roller so that the mixed fiber is thrown toward a fiber receiving surface by the rotating force of the roller, thereby A fiber mat is formed on the face; and (c) inverting the first fiber mat; and (d) stacking the inverted first fiber mat and the second fiber mat so that the low density layers of each fiber mat face each other; and (e) bonding the first and second fiber mats which are superimposed on each other; and (f) bonding fibers together, The first and second fiber mats are formed on different fiber receiving faces, and wherein, Step (c) includes: placing the first fiber mat on a moving surface below the roll used to form the second fiber mat such that the low density layer of the first fiber mat is on the upper side of the first fiber mat; and wherein the low density layer of the first fiber mat placed on the moving surface below the rollers used to form the second fiber mat becomes the fiber receiving surface of the second fiber mat; Wherein, step (d) comprises: A second fiber mat is formed on top of the first fiber mat such that the low density layer of the second fiber mat is formed opposite the low density layer of the first fiber mat. 2. The method of claim 1, wherein the first and second fiber mats are formed using the same roll and the same fiber receiving surface. 3. The method of claim 1, wherein different rolls form the first and second fiber mats. 4. The method of claim 1, wherein the fiber-receiving surface of the first fiber mat causes the first fiber mat to move in an opposite direction to a moving surface located below a roller used to form the second fiber mat, and wherein the fiber-receiving surface of the first fiber mat is disposed above a moving surface located below a roller used to form the second fiber mat, and Wherein, placing the first fiber mat in step (c) comprises: conveying the first fiber mat from one end of the fiber-receiving surface of the first fiber mat, and arranging it under the moving rollers used to form the second fiber mat face such that the low density layer of the first fiber mat is on the upper side of the first fiber mat. 5. The method of claim 1, wherein the fine fibers include inorganic fibers and thermoplastic resin fibers, and the thermoplastic resin fibers serve as a medium for bonding other fibers together. 6. The method of claim 5, wherein the thermoplastic resin fibers comprise polypropylene fibers. 7. The method of claim 6, wherein the polypropylene fibers have a diameter in the range of 15 microns to 17 microns. 8. The method of claim 5, wherein the inorganic fibers comprise carbon fibers. 9. The method of claim 8, wherein the carbon fibers have a diameter of less than 10 microns. 10. The method of claim 1, wherein the coarse fibers comprise sisal fibers. 11. The method according to claim 10, characterized in that the diameter of the sisal fibers is chosen between 80 microns and 250 microns. 12. A fiber mat making machine for use in the method of claim 1 comprising: first and second rotating rollers, each rotating roller having an outer peripheral surface and means for temporarily retaining fibers on the outer peripheral surface; and first and second feeders arranged and configured to feed a mixture of coarse fibers and fine fibers onto the outer peripheral surfaces of the first and second rolls; a first conveyor disposed below the first roller and arranged and configured to receive and convey fibers that are thrown off the first roller as the first roller rotates, thereby forming a first fiber mat on said first conveyor, said first fiber mat comprising a high density layer consisting primarily of fine fibers and a low density layer consisting primarily of coarse fibers; a second conveyor disposed below the first conveyor and the second roller to receive and convey the first fiber mat in an inverted position and to receive the mat thrown off the first mat as the second roller rotates Two rolls of fibers, thereby forming a second fiber mat on the first fiber mat, said second fiber mat comprising a second high density layer consisting essentially of fine fibers and a second low density layer consisting essentially of coarse fibers , so that the first low density layer of the first fiber mat is opposite the second low density layer of the second fiber mat. 13. A fiber mat making machine as claimed in claim 12, wherein the fiber retaining means comprises a plurality of needles extending outwardly from the outer peripheral surfaces of the respective rollers. 14. The fiber mat manufacturing machine according to claim 13, wherein the fiber holding device further comprises a plurality of auxiliary rollers, the auxiliary rollers are located near the outer peripheral surfaces of the corresponding rollers, and each auxiliary roller is separated from the outer peripheral surfaces of the corresponding rollers. Drive a predetermined distance. 15. The fiber mat making machine of claim 12 wherein said first and second conveyors each comprise a conveyor belt driven at a constant speed. 16. A fibrous mat making machine as claimed in claim 15, wherein said first and second conveyors are driven in opposite directions to each other.

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