JPH02164387A - Method for sewing envelope used in outer covering integrated foaming process - Google Patents

Abstract

PURPOSE:To prevent foaming resin from leaking from a needle hole through a base material located on the reverse side by setting the major axis of the bobbin thread at a value which is more than predetermined times the diameter of the needle thread. CONSTITUTION:The major axis of the bobbin thread is set at more than 1.2 times the diameter of the needle thread. Two base materials 1, 1' adjacent each other in their extended form are put together with their back sides out so that their felt layers are opposite to each other, and the sewing portions of the materials 1, 1' are sewed by means of a sewing machine. In this case, a 0.35-mm diameter thread is used as the needle thread 2, and a 0.6-mm diameter thread as the bobbin thread 3. After a needle having the needle thread 2 passed through its thread hole is made to pass through a sewing position (-) from the base material 1 to base material 1' and the needle thread 2 entwined with the bobbin thread 3 disposed on the side of the base material 1', then the needle is pulled out of the base material 1 and next, the unit sewing, whereby the needle thread 2 and bobbin thread 3 are both extended from the sewing position to the next sewing position provided at predetermined distance from the former, is repeated to sew the materials. After a tape made from resin is caused to adhere to only the seam portion of the base material 1 where the needle thread 2 is uncovered and thus the seam portion filled with resin, the sewing portions are then reversed to obtain an outer covering. A needle hole 10 is blocked at the side of the base material 1' by the needle thread 2 and the bottom thread 3, so that the resin is prevented from leaking therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for sewing a skin used in skin-integrated foam molding in which the skin is placed in a mold and then foam-molded. The 81 manufacturing method of the present invention can be used for the skin of automobile headrests, seats, etc. It is used when doing i1%.

[Prior Art] For example, as a headrest for an automobile, a molded body made of foamed resin and covered with a skin made of leather, resin, nonwoven fabric, woven fabric, etc. has been conventionally used. When manufacturing such a headrest, a method has generally been used in which a molded body and a skin are formed separately, and then the molded body is covered with the skin and sewn. However, this method requires a large amount of man-hours and has the disadvantage that the position of the molded body shifts within the skin, resulting in poor appearance quality.

Therefore, in recent years, a method has been developed in which a skin formed in a predetermined shape is placed in a mold, and resin is foamed within the skin to integrally mold and join the molded body and the skin. is becoming mainstream.

Incidentally, the shape of the epidermis is generally three-dimensional.

Therefore, when forming a skin from leather or nonwoven fabric, a sheet-like base material cut into a predetermined shape is aligned with the inner side, sewn with a sewing machine, and then turned over to form a three-dimensional skin.

[Problems to be Solved by the Invention] When sewing using a sewing machine, as shown in FIGS. 8 and 9, by lowering the sewing needle, the upper thread 100 is threaded together with the sewing needle into two stacked bases. The material 401 and 402 are inserted from the front surface to the back surface. After the upper thread 100 is entwined with the lower thread 200 placed on the back side, the sewing needle is raised to return the upper thread 100 to the front side. Next, base material 4
01 and 402 to extend the upper thread 100 and the lower thread 200 to the next sewing position separated by a predetermined interval. Sewing is performed by repeating this unit gi process. At this time, as shown in FIG. 9, the base material 401.402 has needle holes 301.302.
is drilled. Here, the upper thread 1°O is inserted through a thread hole formed in the sewing needle.

Therefore, as shown enlarged in FIG. 10, the base material 401.402 is provided with needle holes 301.3O2 corresponding to the total area of the cross section of the two needle threads 100 and the cross section of the sewing needle.

Note that once the diameter of the needle thread is determined, the diameter of the thread hole is determined, and the diameter of the sewing needle is the smallest diameter that can maintain its strength while maintaining its thread hole.Therefore, once the diameter of the needle thread is determined, The size of the needle hole is uniquely determined.

When the base material subjected to faH is inverted in this way to form a skin and placed in a mold for integral foam molding, the foamed resin leaks from the ε1 holes 301 and 302 and is exposed on the surface, as shown in Figure 11. There were times when it was released. Therefore, it is necessary to seal the seams, which requires a large amount of man-hours.

This leakage of foamed resin is caused by the base material 401 on the surface side (needle thread side).
leakage from the needle hole 301 (arrow △) and leakage from the needle hole 302 of the back side (bobbin thread side) base material 402 (arrow B).
There are different types. The purpose of the present invention is to prevent the foamed resin from leaking from the needle holes 302 of the base material 402 on the back side.

[Means for Solving the Problem] The inventors of the present invention discovered that the needle hole 302 of the base material 402 on the back side
The cause of leakage of foamed resin from was investigated.

As a result, as shown in FIG. 12, most of the needle hole 302 is covered with the two needle threads 100 and the lower thread 200. However, since the needle thread 100 and the bobbin thread 200 have conventionally used threads with the same diameter, it has been found that it is difficult to completely close the needle hole 302 and a gap 303 remains. Based on the knowledge that the diameter of the bobbin thread can be set freely on sewing machines, we conducted experiments with various bobbin thread diameters and found that we were able to use a bobbin thread with a diameter larger than the specified diameter for the needle thread diameter. The present invention was completed by discovering that leakage of the foamed resin from the needle hole 302 on the back side can be prevented by this method.

That is, in the method of sewing a skin for integrally foamed skin molding of the present invention, two sheet-like base materials cut into a predetermined shape are aligned with the inner sides facing each other, and a sewing needle is inserted into the thread hole at one sewing position. is inserted from the front side of the base material toward the back side, and the upper thread is entwined with the bobbin thread placed on the back side.Then, the sewing button is pulled out from the front side of the base material, and then the next button is inserted at a predetermined interval from the Il position. A sewing method in which the base material is sewn to form a skin by repeatedly performing unit sewing in which the upper thread and lower thread are extended to the sewing position, characterized in that the long diameter of the lower thread is 1.2 times or more the diameter of the upper thread. shall be.

In the sewing method of the present invention, the major axis of the bobbin thread is set to 1.
The biggest feature is that it is more than twice as large. Here, the long axis of the bobbin thread refers to the longest diameter of the cross section of the bobbin thread, and if the cross section is oval, it is the long axis, and if the cross section is circular, it is the diameter. If the length of the lower thread (\) is thinner than 1.2 times the diameter of the upper thread, it will be difficult to completely close the needle hole and a gap will occur.

More preferably, it is 1.75 to 2.5 times. Even if the thickness is increased by 2.5 times or more, the effective rack will be saturated and the number of windings on the bobbin will decrease, which is not preferable because the number of bobbin replacements will be extremely increased.

The 81 manufacturing method of the present invention can be carried out using a sewing machine in a conventional manner. Further, the materials of the upper thread and the lower thread are not particularly limited, and threads made of the same materials as conventional threads can be used.

[Function] i! of the present invention! In the '3ii method, two sheet-like base materials cut into a predetermined shape are aligned with the inside sides facing each other, and at the first sewing position, a sewing needle with an upper thread inserted through the thread hole is inserted from the front side of the base material to the back side. After threading the sewing needle through the sewing needle, the sewing needle is pulled out from the front side of the base material, and the upper thread and lower thread are threaded through the thread from the sewing position to the next sewing position at a predetermined distance from the sewing position. Repeat unit sewing to lengthen the length. Here, the long axis of the lower thread is 1.2 times or more the diameter of the upper thread. As a result, as shown in FIGS. 3 and 4, the needle hole in the base material on the back side (lower thread side) is completely covered by the upper thread 1 and the lower thread 2.

[Effects of the Invention] According to the eleventh manufacturing method of the present invention, the needle hole formed in the base material on the back side is closed with the upper thread and the lower thread. Therefore, if integral foam molding is performed using the 19-layered skin, leakage of the foamed resin from that portion can be prevented. In other words, the button type can be closed using the upper thread and bobbin thread just by sewing in the same way as before, without having to seal the seams.
It is possible to reduce man-hours and reduce costs.

[Example] Hereinafter, this will be explained in detail using examples.

(Example 1) In this example, the present invention is applied to the case where the skin of the I\radst of an automobile seat is manufactured by oneself.

First, as shown in a cross-sectional view in FIG. 2, a sheet-like base material in which a Fell 1 layer 11, a polyurethane slab foam layer 12, and a polyurethane film 13 are integrally bonded is prepared. This base material is then cut into a plurality of sheets that form the unfolded shape of the headrest.

Next, the two adjacent base materials 1.1' in the unfolded shape are aligned with their inner sides facing each other so that the respective felt layers 11 face each other, and the sewn parts are sewn using a sewing machine as shown in FIG.

At this time, a polyester thread with a diameter of 0.35 mm was used as the upper thread 2, and a polyester thread with a diameter Q of 6 mm was used as the lower thread 3. The maximum diameter of the sewing machine needle is 0.95 mm, and the diameter of the thread hole is 0.4 mm. Then, insert the upper thread 2 into the thread hole at the first a position.
Insert the sewing machine needle that has been inserted through the base material +41 toward the base material 1-, and after entwining the upper thread 2 with the bobbin thread 3 placed on the base material 1- side, pull the sewing machine needle away from the base material 1. Then, sewing was performed by repeatedly performing intermediate sewing in which the upper thread 2 and the lower thread 3 were extended from the sewing position to the next sewing position at a predetermined interval. The sewing pitch is 4 mm.

The remaining base materials were sewn in the same manner, and the resin tape was glued only to the seam part of the base material 1 where the upper thread 2 was exposed. . The base material 1' from which the bobbin thread 3 is exposed is in the same state as IJly. For comparison, sewing was carried out in the same manner using the same lower thread as the upper thread, and a sealed skin was formed in the same manner.

Each of these skins was placed in a mold, and after the molds were clamped, foamed urethane resin was injected and foamed to perform integral foam molding of the skin. After molding, the mold was opened, the molded product was taken out, and the seam portion of the skin was observed. As a result, foamed resin leaked from the seams when the same thread was used for the upper and lower threads.
There was no leakage of foamed resin from the skin sewn by the v1\J method of the example.

That is, in the skin sewn in this example, as shown in FIGS. 3 and 4, the needle hole 10 on the side of the base material 1 is closed by the upper thread 2 and the lower thread 3, thereby preventing resin from leaking. This is considered to have been prevented.

In this example, the bobbin thread 3 with a perfectly circular cross section was used, but the same result can be obtained by using a bobbin thread 3' with an oval cross section with a major axis (a) of 1.0 mm or more as shown in FIG. Effects can be obtained.

(Example 2) In this example, as shown in FIG.
The procedure is the same as in Example 1 except that the tape 4 made of PP foam with a thickness of 0.6 mm was sewn on the side. That is, the tape 4 and needle thread 2 are exposed on the base material 1 side, and the base material 1-
The lower thread 3 is exposed on the side as in the first embodiment.

This skin was not subjected to sealing treatment as in Example 1, and the skin was integrally foam-molded as it was. In this skin, the needle holes on the base material 1 side were closed with the tape 4, so no leakage of the foamed resin occurred even without sealing treatment.

In this case, since the tape 4 is formed from closed cells, the foamed resin does not penetrate through the tape 4. Then, the tape 4 is compressed by the needle thread 2 and the base material 1 during sewing. At this time, since no compressive force is applied to the needle hole, the compressed portion swells into the needle hole and blocks the needle hole. In addition, on both sides of the tape seam, the drawing force of the needle thread 2 generates a biasing force that biases the tape 4 in the direction of approaching each other.
Close the palms together to cover the seams as shown in the picture. It is thought that these effects prevented the foamed resin from leaking from the needle holes on the base material 1 side.

That is, according to the sewing method of Example 2, the needle holes on both sides formed in the two base materials can be closed at the same time as sewing, so that the number of man-hours can be further reduced compared to the method of Example 1. Can be done.

[Brief explanation of the drawing]

1 to 5 relate to a sewing method according to an embodiment of the present invention,
Figure 1 is an explanatory diagram showing the sewing state, Figure 2 is a sectional view of the base material, Figure 3 is a sectional view of the needle hole part of the II-made skin, and Figure 4 is A of Figure 3. Fig. 5 is a sectional view corresponding to Fig. 3 showing another aspect of the weft thread. Figs. 6 and 7 relate to the sewing method of the second embodiment; is an explanatory view showing the sewing state, and Fig. 7 is a sectional view of the main part of the molded body. Figs. 8 to 12 relate to the conventional sewing method, and Fig. 8 shows the upper thread and lower thread during sewing. An explanatory diagram showing the relationship between threads, Fig. 9 is a cross-sectional view of the needle hole portion of the sewn skin, Fig. 1o is a cross-sectional view [3-8] of Fig. 9, and Fig. 11 is a cross-sectional view of the main part of the molded body. , FIG. 12 is a CC sectional view of FIG. 9. 1.1″...Base material 2... Upper thread 3... Lower thread 4... Tape 10... Needle hole patent Applicant Tokai Kasei Kogyo Co., Ltd. Agent Patent Attorney Hiroshi Okawa

Claims (1)

[Claims] (1) Align two sheet-like base materials cut into a predetermined shape with the front and center sides facing each other, and at one sewing position point the sewing needle with the upper thread inserted through the thread hole from the front side of the base material to the back side. After the upper thread has been inserted and entwined with the lower thread placed on the back side, the sewing needle is pulled out from the front side of the base material, and then the upper thread is moved to the next sewing position at a predetermined distance from the sewing position. and a sewing method in which the base material is sewn to form a skin by repeatedly performing unit sewing to lengthen the bobbin thread, characterized in that the major axis of the bobbin thread is 1.2 times or more the diameter of the needle thread. A method for sewing a skin for integral foam molding.