JPH0976349A - Three-dimensional bonding method for skin and sheet material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a bag-shaped skin having high three-dimensional accuracy from a plurality of skin pieces without using sewing or adhesion. SOLUTION: At least a surface side thermoplastic sheet material is cut into a predetermined shape to form a plurality of sheet pieces 10, 11 and the sheet pieces are fitted to a plurality of split molds 2, 3 so that the rear surfaces thereof are opposed to the mold surfaces of the molds 2, 3 to be shaped along the shapes of the mold surfaces of the molds 2, 3 and the peripheral edge parts of a pair of the mutually adjacent sheet pieces are arranged to mold splitting surfaces 25, 35 in such a state that the sheet pieces are fitted to be grasped and a pair of the contact sheet pieces are mutually welded by vibration welding. Since the sheet pieces are welded under vibration in the state shaped along the mold surfaces of the molds, the sheet pieces can be bonded with high dimensional accuracy and sewing also becomes unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag-like skin used for integral foam molding and a three-dimensional joining method of sheet materials most suitable for manufacturing the skin.

[0002]

2. Description of the Related Art Headrests, armrests of automobiles,
Cushioning parts such as a lid or a seat of a console box generally have a two-layer structure of a skin and a foam-molded product, or a three-layer structure including a core material. In order to manufacture such a cushion component, in the old days, a bag-shaped skin that was previously sewn was put on a foam-molded product that had been molded into a predetermined shape, but in recent years, the skin and the core material have been placed inside the mold. The mainstream method is a method in which foamed resin is foamed in an arranged state to integrally bond the outer skin and the core material, thereby performing integral foam molding.

When a cushion component having a three-dimensional three-dimensionally shaped skin such as a headrest is manufactured by integral foam molding, the skin must be formed into a bag having a predetermined three-dimensional shape in advance. In order to form the outer skin into a bag having a predetermined three-dimensional shape in this manner, the outer skin material is cut into a plurality of outer skin pieces obtained by cutting the developed shape of the desired three-dimensional shape. A method of manufacturing by sewn a part and then reversing the part is performed. There is also a method of joining with an adhesive instead of sewing, and a method of combining sewing and joining with an adhesive is also known.

[0004]

However, it is difficult to mechanize the work of forming a bag shape by sewing a plurality of skin pieces, because the shape is a three-dimensional three-dimensional shape, and it is necessary to rely on manual work. . As a result, the man-hours are great, the sewing length and position are low in accuracy, and the sewn portion is loosened, and the outer skin is wrinkled or loosened after the integral foam molding. Such a problem similarly occurs in joining with an adhesive.

In the case where a three-dimensionally sewn outer skin is placed in a mold for integral foam molding, the foam resin leaks from the seam, or the seam is impregnated by the foam resin and solidifies to form a seam portion. The tactile feeling becomes harder than other parts, and defects in appearance or tactile feeling may occur. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a seamless skin having high three-dimensional dimensional accuracy, and to easily and stably form such a skin.

[0006]

The feature of the skin of the present invention for solving the above-mentioned problems is that the peripheral portions of a plurality of skin pieces are three-dimensionally joined by welding to form a substantially three-dimensional bag-like shape. is there. Further, the feature of the three-dimensional joining method of the present invention most suitable for manufacturing the above-mentioned skin is that at least the surface side is cut into a plurality of sheet pieces by cutting a thermoplastic sheet material into a predetermined shape, and from a plurality of split molds. Is formed into a die surface shape by facing the back sides of a plurality of sheet pieces to the plurality of die surfaces of a mold having a predetermined concave die surface, and forming a pair of sheet pieces that are adjacent to each other. A step of arranging and sandwiching the joint portion of the peripheral portion on the mold splitting surface in a state of being aligned with the front surface, and a pair of sheet pieces abutting at the joint portion by vibrating at least one split die together with the sheet piece in contact with the split die. And a step of welding them to each other by frictional heat.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the epidermis of the present invention, the peripheral portions of a plurality of epidermis pieces are three-dimensionally joined by welding to form a three-dimensional, substantially bag-like shape. Therefore, since there is no seam, leakage of resin from the seam and impregnation of the seam into the seam when used for integral foam molding do not occur, and a cushion component excellent in appearance quality and tactile quality can be manufactured.

In the three-dimensional joining method of the present invention, the sheet material is first cut into a predetermined shape to form a plurality of sheet pieces. The predetermined shape here means a part of the developed shape of the desired three-dimensional shape, and the desired three-dimensional shape can be obtained by three-dimensionally combining a plurality of sheet pieces. Further, at least the surface side of this sheet material is thermoplastic, and it can be welded by bringing the surfaces of a plurality of sheet pieces into contact with each other and heating them. The entire sheet material may be thermoplastic, or a sheet in which a thermoplastic material sheet is laminated only on the front surface side can be used.

Next, the back surface sides of the plurality of sheet pieces are made to face the mold surfaces of a mold having a predetermined shape and composed of a plurality of split molds, and the mold surface shape is given. A pair of sheet pieces, which are shaped and adjacent to each other, are arranged and sandwiched by arranging a joint portion of a peripheral edge portion on a mold splitting surface in a state in which the sheet pieces are aligned with the front surface. Vacuum or compressed air can be used to shape the sheet piece along the concave mold surface shape. As a result, each sheet piece is reliably along the mold surface, and a highly accurate three-dimensional solid shape can be obtained.

In this state, when at least one split die is vibrated together with the sheet piece in contact with the split die, friction heat is generated in the pair of sheet pieces sandwiched by the split surfaces, and at least the heat on the surface side is generated. The plastic parts are melted and welded together. As a result, the pair of sheet pieces sandwiched is vibration-welded to each other at the joint portion to be integrated. Since vibration welding is used, it is possible to vibrate even if the parting line is a curve, and it is possible to weld all joints by vibrating in one direction. However, since the clamping force may be insufficient on the parting surface extending in the direction substantially perpendicular to the vibration direction, the parting surface (cutting part) should be inclined so that it is inclined at an angle of at least 25 ° or more from the direction perpendicular to the vibration direction. It is desirable to design the shape and vibration direction. Note that, depending on the case, sewing and adhesion may be partially used together.

Further, it is necessary to surely bring the pair of sandwiched sheet pieces into close contact with the mold-dividing surface and to vibrate them. For this purpose, for example, the mold-dividing surface is knurled or the mold-dividing surface is subjected. Is composed of rubber, etc.
It is preferable to increase the frictional resistance between the molding surface and the sheet piece. And after the welding of the peripheral edge of the sheet piece is completed,
The shaping along the mold surface is released, and the three-dimensional sheet material is taken out by opening the mold.

The sheet materials three-dimensionally joined in this way are turned upside down from the openings provided appropriately so that the surface is on the front side and the joined portion is on the inside of the bag. Then, for example, it is placed in a predetermined foam molding die and is used for integral foam molding or the like.

[0013]

EXAMPLES The present invention will be described in more detail below with reference to examples. In this embodiment, the present invention is applied to the automobile headrest skin shown in FIG. 1 and a method for manufacturing the same. First, a headrest skin material is prepared, and the developed shape of the headrest 1 shown in FIG. 1 is cut into two kinds of skin pieces 10 and 11 as shown in FIG. The skin piece 10 constitutes the upper surface, front surface and bottom surface of the headrest, and the skin piece 11 constitutes two side surfaces and a rear surface of the headrest. As shown in FIG. 6, the skin pieces 10 and 11 are made of polyvinyl chloride design skin materials 10a and 11a, and design skin materials 10a and 1a.
1a Slab foam 10b, 1 laminated on the back side
1b and urethane films 10c and 11c laminated on the surfaces of the slab foams 10b and 11b.

Next, an upper mold 2 and a lower mold 3 as shown in FIGS. 3 and 4 are prepared. The upper mold 2 has a mold surface 20 having a concave shape corresponding to the upper surface of the headrest 1, and has a cavity 21 on the rear surface side.
It is fixed to the fixing plate 22 via. In addition, the fixed plate 2 has a plurality of vacuum holes 23 communicating the mold surface 20 and the cavity 21.
A vacuum pump (not shown) is connected to a suction hole 24 which is provided in 2 to connect the cavity 21 to the outside. Further, the upper mold 2 is formed with a mold splitting surface 25 that extends corresponding to the shape of the boundary between the skin pieces 10 and 11 and is formed in a rail shape. The surface of the mold splitting surface 25 is knurled. There is.

The lower mold 3 has a mold surface 30 having a concave shape corresponding to the front surface, the bottom surface and the rear surface of the headrest 1, and is fixed to a fixing plate 32 via a cavity 31 on the back surface side. Further, a vacuum pump (not shown) is connected to a suction hole 34 that has a plurality of vacuum holes 33 that communicate the mold surface 30 and the cavity 31 and that is provided in the fixing plate 32 so that the cavity 31 communicates with the outside. Further, in the lower mold 3, a mold splitting surface 35 extending corresponding to the shape of the boundary portion between the skin piece 10 and the skin piece 11 is projected and formed in a rail shape, and the surface of the mold splitting surface 35 is knurled. There is.

Then, the peripheral edge of the outer skin piece 11 is held by the fixed frame body 26, which is arranged in the upper mold 2, and the outer skin piece 11 is guided along the mold surface 20 of the upper mold 2 by vacuum suction from the suction holes 24. To shape. The skin piece 11 is the slab foam 1 on the back surface.
The 1b side faces the mold surface 20 of the upper mold 2. The fixed frame body 26 is located outside the mold dividing surface 25, and
In this state, the skin piece 11 is pressed.

Further, the peripheral portion of the skin piece 10 is held by the fixed frame 36, which is arranged in the lower mold 3, and the skin piece 10 is guided along the mold surface 30 of the lower mold 3 by vacuum suction from the suction holes 34. To shape. The skin piece 10 is a slab foam 10 on the back surface.
The b side faces the mold surface 30 of the lower mold 3. The fixed frame body 36 is located outside the mold splitting surface 35, and the skin piece 10 is pressed against the mold splitting surface 35.

In this way, the fixed frame members 26, 36 are used to form the skin piece 1.
Since the peripheral edges of 0 and 11 are held along the mold surfaces 20 and 30, tensile stress acts on the skin pieces 10 and 11 so that wrinkles and twists do not occur and the outer shape does not shift. Therefore, the skin pieces 10 and 11 are precisely shaped into a desired shape. In that state, as shown in FIG.
Then, the lower die 3 is clamped with a force of 600 kg. As a result, the upper mold 2 and the lower mold 3 are pressed against the mold splitting surfaces 25 and 35 through the skins 10 and 11, respectively, and the skins 10 and 11 are made of polyvinyl chloride at the positions of the mold splitting surfaces 25 and 35. Skin material 1
0a and the design skin material 11a are brought into contact with each other and pressed against each other.

Only the upper mold 2 has the maximum amplitude (on both sides)
At 1.8 mm, at a frequency of 240 times / sec, arrow A in FIG.
-Vibrate in the A'direction. Then, the skin piece 11 is brought into close contact with the die-splitting surface 25 of the upper mold 2 by knurling, and slides on the skin piece 10 closely attached to the die-splitting surface 35 of the lower mold 3, and the skin pieces 11 and 10 are frictionally heated to separate Design skin materials 10a, 11
a is welded to each other at the positions of the mold splitting surfaces 25 and 35. Since the skin pieces 10 and 11 are precisely shaped into a desired shape, the welding position is also exactly the position of the mold splitting surfaces 25 and 35.

Then, the molding surface 2 is vibrated for 2 to 5 seconds.
After the welding is completely performed on all of the parts 5 and 35, the vibration is stopped, the vacuum suction is also stopped, the holding of the fixing frames 26 and 36 is released, and the mold is opened, so that the skin piece 10 and the skin piece 11 are separated from each other. A precise three-dimensional three-dimensionally shaped skin that is integrally joined at the peripheral portion can be obtained. The obtained skin is turned upside down from the opening (not shown) and the design skins 10a and 11a are formed as shown in FIG.
The side is the front side, and the joint is the epidermis located inside. Then, the headrest is placed in a predetermined mold for foam molding together with the core material, and the headrest is formed by foam molding with integral skin.

At this time, the split surfaces 25, 35 are formed at the joints.
Since the entire surface along the line is melted and solidified by welding, the leakage of the foamed resin does not occur, and the impregnation and solidification of the seam which has conventionally occurred does not occur. Therefore, a headrest excellent in appearance quality and tactile quality can be obtained.

[0022]

According to the three-dimensional joining method of the present invention, the three-dimensional joining, which has been conventionally performed by sewing or bonding, can be performed by using a mold, so that the dimensional accuracy is remarkably improved. Since most of the range can be joined at the same time in a short time, the number of joining steps can be significantly reduced.

According to the skin of the present invention formed by using the three-dimensional joining method of the present invention, since the dimensional accuracy is remarkably excellent, slack and wrinkles are not generated when it is used for integral foam molding of the skin. It is prevented and the appearance quality is significantly improved. Further, since there is no seam, leakage of the foamed resin and impregnation and solidification of the foamed resin do not occur, and it is possible to reliably and stably manufacture a skin-integrated foamed molded product excellent in appearance quality and touch.

[Brief description of drawings]

FIG. 1 is a perspective view of a headrest having a skin manufactured according to an embodiment of the present invention.

FIG. 2 is a perspective view of a skin piece used in an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a state in which a skin piece is held by an upper mold used in an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a lower mold used in one embodiment of the present invention in which a skin piece is held.

FIG. 5 is a cross-sectional view showing a state in which the skin piece is shaped and vibrated along the mold surfaces of the upper mold and the lower mold in one embodiment of the present invention.

FIG. 6 is a cross-sectional view of a main part of the skin joined in one embodiment of the present invention.

[Explanation of symbols]

1: Headrest 2: Upper mold 3: Lower mold 10,11: Skin piece 20,20: Mold surface 23, 33: Vacuum hole 26, 36: Fixed frame body

Claims (2)

[Claims] 1. An epidermis, characterized in that the peripheral edges of a plurality of epidermis pieces are three-dimensionally joined by welding to form a substantially three-dimensional bag-like shape. 2. A step of cutting a thermoplastic sheet material at least on the surface side into a predetermined shape to form a plurality of sheet pieces, and a plurality of molds of a predetermined shape having a concave mold surface composed of a plurality of split molds. The back surfaces of the plurality of sheet pieces are made to face each other along the mold surface to form the shape of the mold surface, and a pair of the sheet pieces adjacent to each other are joined to the front and back to form a joint portion of the peripheral portion. A step of arranging and sandwiching on a mold splitting surface, and a step of vibrating at least one of the split dies together with the sheet piece in contact with the split die and welding a pair of the sheet pieces abutting at the joint by friction heat A three-dimensional joining method for sheet materials, comprising: