JP3560178B2 - Manufacturing method of seat back frame - Google Patents

Description

中空成形体の肉厚は、いずれも２．５ｍｍとした。
【００２８】
試験は、次のような項目について行なった。
接着強度：上記試料を厚さ方向に速度１０ｍｍ／ｍｉｎで引張った時の最大応力 （ｋｇ／ｃｍ^２）
曲げ強度：ＪＩＳ−Ａ−９５１１に基づき、上記試料を厚さ方向にスパン３００ｍｍ 、速度１０ｍｍ／ｍｉｎで曲げた時の最大応力（ｋｇ／ｃｍ^２）
弾性率 ：上記曲げ強度測定時の弾性変形領域内における応力−歪曲線の傾き （ｋｇ／ｃｍ^２）
【００２９】
測定結果は表１に示す通りであった。
【００３０】
【表１】

【００３１】
表１より、軟化点以上であれば、中空成形体１５と発泡成形体１８とは強固に接着しており、又、接着強度が高いほど剛性の指標となる曲げ強度も高いことがわかる。
尚、曲げ強度が３０ｋｇ／ｃｍ^２ 以下ではシートバックフレームの実用強度に達しない。
【００３２】
【発明の効果】
以上の如く、本発明のシートバックフレームの製造方法によれば、軽量化を十分に達成でき、リサイクル性も良好なシートバックフレームを製造できるとともに、シートバックフレームの製造工程数を削減でき、製造時間を短縮化できる。
【図面の簡単な説明】
【図１】本発明のシートバックフレームの外観斜視図である。
【図２】本発明のシートバックフレームによりシートバックを完成する方法を示す説明図である。
【図３】本発明のシートバックフレームの製造方法を実施する製造装置の外観斜視図である。
【図４】本発明のシートバックフレームの製造方法を示す説明図である。
【図５】図４のＡ部拡大図である。
【図６】従来のシートバックフレームの外観斜視図である。
【符号の説明】
１ シートバックフレーム
４ ヘッドレストステー支持部
１０ 成形用金型
１１ 成形用金型
１２ 用役パイプ
１５ 中空成形体
１８ 発泡成形体
Ａ パリソン
Ｂ 熱可塑性予備発泡粒子[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a seat back frame that constitutes a seat back provided in a vehicle, particularly, an automobile.
[0002]
[Prior art]
A seat back for a vehicle, for example, an automobile has a structure in which a cushioning material is attached to a seat back frame and a covering material is covered on the seat back frame. The seat back frame 51 is generally shown in FIG. As shown, iron members such as a headrest stay holder 53, a side frame 54, and a backup material 55 are attached to an iron pipe frame 52 by welding.
[0003]
As described above, since the seat back frame is made of iron, even the front seat frame is heavy, weighing 3 to 4 kg, which contributes to poor fuel economy. Therefore, there is a problem that the number of manufacturing steps is large and the manufacturing takes time.
[0004]
Therefore, in order to reduce the weight of the seat back frame and reduce the number of manufacturing steps, a method of manufacturing a plastic seat back frame to which blow molding is applied has already been disclosed in JP-A-04-103331 and JP-A-04-223127. It is proposed in publications and the like.
[0005]
[Problems to be solved by the invention]
However, in the above manufacturing method, the thickness of the hollow molded body is increased in order to improve the strength of the seat back frame, and particularly, the portion requiring high strength is further increased in thickness by a special device, Since a parison made of a plastic resin contains a filler such as glass fiber as a reinforcing material, the weight is reduced by only about 1 kg as compared with a conventional iron-made one, and a sufficient weight reduction has not been achieved even with a plastic-made one.
[0006]
The present invention has been made in view of the above-described problems, and achieves a sufficient weight reduction by using plastic without losing strength, and further reduces the number of manufacturing steps. An object is to provide a manufacturing method.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a seat back frame according to the present invention comprises inserting a utility pipe into a parison made of a thermoplastic resin suspended in a molding die, and blow molding to form a hollow molded body. Then, when the temperature of the hollow molded body is equal to or higher than the softening point, the hollow molded body is filled with thermoplastic pre-expanded particles, and heat-fused to form a foamed molded body. A method for manufacturing a detachable seat back frame, wherein the thermoplastic resin and the thermoplastic pre-expanded particles are made of the same resin, and a hole formed after detaching the utility pipe is inserted into a headrest stay supporting portion. It is characterized by a hole.
[0008]
By making the thermoplastic resin and the thermoplastic pre-expanded particles the same type of resin, the bond between the hollow molded article and the foam molded article becomes strong, and a hole formed after detaching the utility pipe. Since the portion is an insertion hole of the headrest stay support portion, the number of manufacturing steps can be reduced.
[0009]
Further, it is preferable that a circumferential groove is formed at an appropriate position of the utility pipe so that a projection for locking the headrest stay is formed in the insertion hole of the headrest stay support portion.
[0010]
【Example】
Hereinafter, embodiments of the seat back frame of the present invention will be described with reference to the drawings.
[0011]
The seat back frame 1 of the present invention is obtained by forming a foam molded body 3 by heat-fusing thermoplastic pre-expanded particles in a hollow molded body 2 obtained by blow molding a thermoplastic resin, as shown in FIG. The headrest stay support portion 4, the side frame portion 5, and the backup portion 6 are integrally formed as a hollow molded body 2.
[0012]
In the present invention, since the foam molded body 3 serves as a reinforcing material, the seat back frame has a sufficient strength even when the hollow molded body 2 is made thin, and is lighter than a thick hollow molded body.
Also, it is not necessary to include a filler such as heavy glass fiber as a reinforcing material, and it is not necessary to increase the thickness even in a portion requiring high strength, and the seat back frame becomes lighter.
Needless to say, it is not necessary to use a special device for thickening the thickness, and the manufacturing cost can be reduced.
[0013]
As shown in FIG. 2, the seat back frame 1 of the present invention can complete the seat back 9 by inserting the seat back frame 1 inside the cushion material 7 and covering the surface material 8 from above. it can.
[0014]
Next, a method for manufacturing the seat back frame of the present invention will be described with reference to FIGS.
[0015]
First, as shown in FIG. 3, a parison A made of a thermoplastic resin is hung between the opened molding dies 10 and 11, the molding dies 10 and 11 are closed, and the tip of the utility pipe 12 is molded. It is inserted into the molding dies 10, 11 along the pipe insertion grooves 10a, 11a formed in the molding dies 10, 11.
[0016]
Here, as the thermoplastic resin, polyethylene, polypropylene, ABS and the like can be used, but in this example, polypropylene (softening point 110 ° C.) was used.
[0017]
Also, as shown in FIG. 5, a circumferential portion is formed at an appropriate position of the utility pipe 12 so that a projection 13a for locking the headrest stay is formed in the insertion hole 13 of the headrest stay support portion 4 after molding. It is preferable to form the direction groove 12a.
[0018]
Thereafter, the air supply valve 14 is opened, air is blown into the parison A through the slit hole 12b formed in the utility pipe 12, and a hollow molded body 15 is formed by blow molding as shown in FIG.
At this time, air was blown at a pressure of 6 kg / cm ² G for 10 seconds, and the temperature of the hollow molded body 15 was 150 ° C., which was higher than the softening point of polypropylene.
[0019]
Next, when the temperature of the hollow molded body 15 is equal to or higher than the softening point, the hollow molded body 15 is filled with the thermoplastic pre-expanded particles B by the filling gun 16 as shown in FIG.
[0020]
Here, as the thermoplastic pre-expanded particles B, it is preferable to use the same type as the thermoplastic resin, and when the thermoplastic resin is polyethylene, pre-expanded particles of polyethylene or polyethylene-styrene copolymer resin, In the case of polypropylene, it is preferable to use pre-expanded particles of polypropylene, and in the case of ABS, it is preferable to use pre-expanded particles of polystyrene or ABS.
Since polypropylene was used as the thermoplastic resin in this example, pre-expanded particles of polypropylene were used.
[0021]
Thereafter, the steam supply valve 17 is opened, and steam is blown into the hollow molded body 15 through the slit hole 12b formed in the utility pipe 12 at a pressure of 3.5 kg / cm ² G for 20 seconds, as shown in FIG. Then, the pre-expanded particles B were heat-fused with each other to form an expanded molded article 18 in the hollow molded article 15.
[0022]
A similar resin is used as the thermoplastic resin and the thermoplastic pre-expanded particles B, and the pre-expanded particles B are heated and fused when the temperature of the hollow molded product 15 is equal to or higher than the softening point. Since the body 18 is firmly heat-fused and the rigidity is improved, a plastic seat back frame having a strength not inferior to an iron seat back frame can be formed.
Further, by making the hollow molded body 15 and the foam molded body 18 of the same type of resin, the recyclability of the product is also improved.
[0023]
Next, the drain discharge valve 19 is opened, and while the steam condensed water in the foamed molded body 18 is vacuum-sucked from the slit hole 12b formed in the utility pipe 12, the hollow molded body 15 is formed through the molding dies 10, 11. The integrated molded body where the foam molded body 18 is fused is cooled.
[0024]
Then, as shown in FIG. 4 (D), the utility pipe 12 is forcibly pulled out of the integrally molded body, and the molding dies 10, 11 are opened to take out the integrally molded body.
Here, as shown in FIG. 5, a hole formed after the utility pipe 12 is pulled out becomes an insertion hole 13 of the headrest stay support portion 4, and a portion corresponding to the circumferential groove 12 a of the utility pipe 12. Are projections 13a for locking the headrest stay.
[0025]
In this manner, by forming the hole formed after the utility pipe 12 is pulled out as the insertion hole 13 of the headrest stay support portion 4, it is necessary to attach the headrest holder by welding like an iron seat back frame. And the number of manufacturing steps can be reduced.
[0026]
Next, the degree of thermal fusion between the hollow molded body 15 and the foam molded body 18 depending on the temperature of the hollow molded body 15 when the pre-expanded particles B were heated and fused in the hollow molded body 15 was measured.
[0027]
The following samples were used.

The thickness of each hollow molded body was 2.5 mm.
[0028]
The test was performed on the following items.
Adhesive strength: maximum stress (kg / cm ² ) when the above sample was pulled in the thickness direction at a speed of 10 mm / min.
Flexural strength: Maximum stress (kg / cm ² ) when the above sample was bent in the thickness direction at a span of 300 mm and a speed of 10 mm / min based on JIS-A-9511.
Elastic modulus: slope of the stress-strain curve in the elastic deformation region at the time of the above-mentioned bending strength measurement (kg / cm ² )
[0029]
The measurement results were as shown in Table 1.
[0030]
[Table 1]

[0031]
From Table 1, it can be seen that if the softening point or higher, the hollow molded body 15 and the foam molded body 18 are firmly bonded, and the higher the bonding strength, the higher the bending strength, which is an index of rigidity.
When the bending strength is 30 kg / cm ² or less, the strength does not reach the practical strength of the seat back frame.
[0032]
【The invention's effect】
As described above, according to the method for manufacturing a seat back frame of the present invention, a weight reduction can be sufficiently achieved, a seat back frame having good recyclability can be manufactured, and the number of manufacturing steps of the seat back frame can be reduced. Time can be reduced.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a seat back frame of the present invention.
FIG. 2 is an explanatory view showing a method of completing a seat back with the seat back frame of the present invention.
FIG. 3 is an external perspective view of a manufacturing apparatus for performing the method for manufacturing a seat back frame of the present invention.
FIG. 4 is an explanatory view showing a method for manufacturing a seat back frame of the present invention.
FIG. 5 is an enlarged view of a portion A in FIG. 4;
FIG. 6 is an external perspective view of a conventional seat back frame.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Seat back frame 4 Headrest stay supporting part 10 Molding die 11 Molding die 12 Utility pipe 15 Hollow molded body 18 Foamed molded article A Parison B Thermoplastic pre-expanded particles

Claims (2)

A utility pipe is inserted into a parison made of a thermoplastic resin suspended in a molding die, blow molded to form a hollow molded body, and then when the temperature of the hollow molded body is equal to or higher than the softening point. A method of manufacturing a seat back frame, in which a hollow molded body is filled with thermoplastic pre-expanded particles, heat-fused to form a foam molded body, and then a utility pipe is detached, wherein the thermoplastic resin and the thermoplastic resin are separated. A method for manufacturing a seat back frame, wherein the plastic pre-expanded particles are made of a similar resin, and a hole formed after detaching the utility pipe is an insertion hole of a headrest stay supporting portion. A circumferential groove is formed at an appropriate position of the utility pipe so that a convex portion for locking the headrest stay is formed in an insertion hole of the headrest stay support portion. 2. The method for manufacturing the seat back frame according to 1.

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