JP2963642B2 - Headrest manufacturing 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 of manufacturing a headrest attached to an upper end of a seat back of a vehicle or the like.

[0002]

2. Description of the Related Art A headrest is attached to the upper end of a seat back of an automobile or the like so as to protect the occupant's head and provide comfort. These headrest recipes include:
Only the insert is set in the foaming mold, the foaming material is poured, and the foam and the cushion material and the insert are integrated with a skin such as fabric in the post process (first production method). After inserting the insert into the bag-shaped skin by slash molding, rotation molding, etc., set it in a foaming mold, pour foaming material from the slits provided in the skin, foam-mold, and form a cushion integrated with the skin and insert. There is a method in which a material is formed (second manufacturing method).

[0003] The second manufacturing method will be described more specifically.
As shown in FIG. First, a bag-shaped outer skin 8 is formed by sol slash molding or the like, and a slit 8 for injecting a foaming material, which also serves as a slit for inserting an insert together with the stay hole 82, is formed.
Open 1 Next, the insert 9 is inserted into the skin 8 and the subassay is set in a foaming mold. Thereafter, the slit 81 is expanded and inserted, an injection machine is inserted into the skin, and a foaming material is injected. I do. After foam hardening, the product is removed from the mold, the headrest integrated with the skin is taken out, and finishing processing such as deburring is performed to produce a product.

[0004]

However, in the conventional method of manufacturing a headrest according to the second manufacturing method, the slit 81 is simply cut open, and foaming is performed in a later step by the unevenness of the skin 8 as shown in FIG. And the step β as shown in FIG. 14B. In addition, since the slit 81 was long, the slit portion was opened by the foaming pressure of the foaming material, and the foaming material was easily leaked from here. As a countermeasure against leakage of the foaming material, there is a method in which a sheet material or the like is interposed (JP-A-53-80474, JP-B-3-39448, etc.), but the sheet material must be held by an insert. Also, it was an extra parts procurement item, which led to an increase in cost.

The present invention solves the above-mentioned problems, and provides a method of manufacturing a headrest which eliminates problems such as leakage of a foaming material from a slit, opening of a mouth, and a step without using a material such as a sheet material. With the goal.

[0006]

Means for Solving the Problems To achieve the above object, the gist of the first invention is to insert an insert into a bag-like skin by slash molding or rotation molding, and then inject foaming material into the skin. In a method of manufacturing a headrest that performs foam molding integrally with a skin, a molding die is used in which two cylindrical bodies are erected on a cavity surface and a short plate is erected from one of the cylindrical bodies toward the other cylindrical body. After forming the coating body relating to the skin, the groove formed by the short plate is expanded or pushed to form a slit at the bottom of the groove, and the coating formed on the tip end surface of the cylindrical body is removed. Remove the hole and complete the skin first. Then, after that, the insert is inserted into the skin and both stays of the insert are arranged outside the skin through the circular holes. Then, a foaming material is injected into the skin through the slit, and a foam-integrated cushion material is formed by foam molding. And a method of manufacturing a headrest. Here, the “cylindrical body” includes an elliptical cylindrical body, a polygonal cylindrical body, and the like that mimic a cylindrical body. Similarly, "circular hole"
Includes ellipses and polygons. In the “short plate starting from one of the cylinders and heading toward the other cylinder”, the short plate does not reach the other cylinder. The method for manufacturing a headrest according to the second invention is the first invention, wherein the base width H [mm] of the insert is provided.
In contrast, the length L [mm] of the slit is H ≦ L ≦ H +
25. Here, the condition is L ≧ πK / 2, where K represents the outer diameter of an injection head for injecting the foaming material into the skin, and its unit is [mmφ].
It is.

[0007] The gist of the third invention is a method of manufacturing a headrest in which after inserting an insert into a bag-shaped skin by slush molding or rotation molding, a foaming material is injected into the skin to perform foam molding integrally with the skin. Using a mold in which two cylindrical bodies are erected on the cavity surface and a short plate is also erected in an intermediate region connecting the two cylindrical bodies, the coating body relating to the skin is formed, and after forming, the short plate is formed. The formed groove is expanded or pushed to provide a slit at the bottom of the groove, and at the same time, the film formed on the tip end surface of the cylindrical body is removed to form a circular hole to complete the skin first. Then, after that, the insert is inserted into the skin and both stays of the insert are arranged outside the skin through the circular holes. Then, a foaming material is injected into the skin through the slit, and a foam-integrated cushion material is formed by foam molding. And a method of manufacturing a headrest. Here, in "the short plate is also provided upright in the intermediate region connecting the two cylinders", it is assumed that the short plate does not abut on both the cylinders.
The manufacturing method of the headrest of the fourth invention is the third invention,
The insert is formed by bending a rod-shaped body into a U-shape, and the length L [mm] of the slit is πK / 2 ≦ L ≦ (πK / 2) +2 with respect to the outer diameter K [mmφ] of the injection head.
5 is satisfied. Here, the “rod-like body” includes a solid body and a pipe such as a pipe.

[0008] The method for manufacturing a headrest according to the fifth aspect of the present invention comprises:
The first to third inventions are characterized in that after inserting the insert into the skin, a predetermined amount of a foaming material is injected from the slit, and then these are set in a foaming mold and foamed.

[0009]

According to the headrest manufacturing method of the present invention, since the slit formed by the short plate is smaller than that of the conventional product, the slit has a function of closing itself and has a structure in which the foaming material does not easily leak. . Further, if a slit is formed at the groove bottom between the tongue pieces formed by the short plate, the foaming pressure acts in a direction to close the slit from both sides of the tongue piece in the foam molding process, so that the opening does not occur. The presence of the tongue pieces prevents the slit edges from overlapping as shown in FIG. Even if the insert is provided with a reinforcing plate or the like at its base, according to the second invention, it is possible to have a minimum suitable slit length according to the base width,
Using this slit, insert insertion into the epidermis is also possible. On the other hand, what constitutes an insert with a rod
As in the fourth invention, the slit length Lmm is set to πK / 2 ≦ L ≦ πK / 2 + 2 with respect to the outer diameter K [mmφ] of the injection head.
By setting it within the range of 5, the slit length can be made into a small slit that can be used for both insertion of the insert and injection of the foaming material, thereby preventing leakage of the foaming material. Further, as in the fifth invention, after inserting the insert into the skin, a predetermined amount of foaming material is injected from the slit, and thereafter, these are set in a foaming mold and foaming is performed. Since the skin is bag-shaped and has a shape-retaining property and the slit can be easily pushed open, the injection of the foaming material into the skin can be surely performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. (1) Embodiment 1 FIGS. 1 to 10 show one embodiment of a method for manufacturing a headrest according to the present invention. FIG. 1 is a perspective view of a mold for forming a skin, and FIG.
Is a longitudinal sectional view of FIG. 1, FIG. 3 is an enlarged perspective view around a short plate, FIG.
Is a cross-sectional view in which the skin is formed by the mold of FIG. 1, FIG. 5 is a perspective view of the skin, FIG. 6 is an enlarged view around the short plate and the columnar body in FIG. 4, and FIGS. FIG. 9 is a perspective view showing a state in which an insert is inserted into a skin, and FIG. 10 is a cross-sectional view showing a state in which these are set in a foaming mold after foaming raw materials are injected into the skin and foam molding is completed. FIG.

The method of manufacturing the headrest A is as follows. The insert 4 is inserted into the skin 1 formed in a bag shape in advance, and in this state, a predetermined amount of the foaming raw material G is injected into the skin 1 as it is. Is set in a foaming mold T and made by foam molding. Prior to the formation of the cushion material 5 by foam molding, the skin 1 is prepared. The skin 1 is formed on the cavity surface 2a by forming the coating 3 with the forming die 2 which forms the outer shape of the headrest (FIG. 4), and then the groove 31 of the coating 3 is formed.
Is formed by providing a slit 11 and a circular hole 12 (FIGS. 7 and 8).

First, the mold 2 relating to the skin 1 will be described. The molding die 2 is a slash molding die (electroforming mold) for producing a film body 3 at a stage immediately before the bag-like skin 1 surrounding the pillow-shaped cushion material, and has a cavity mold 21 and a lid mold 22 (FIG. 1). The cavity mold 21 and the lid mold 22 each have a cavity surface 2a having the same shape as the outer shape of the headrest A on the inner surface by closing the mold, and a flange 21 having skirt portions 211a and 221a at the ends to enhance a sealing function at the time of closing the mold.
1,221.

The lid mold 22 is provided with two cylindrical bodies 223 and 223 to be inserted into a stay on the cavity surface 2a into the mold. The upper surface 2231 of the cylindrical body 223 is concavely curved as shown in FIG. Then, starting from the one cylindrical body 223 toward the other cylindrical body, the short plate 222
Is fixed in a standing state. The short plate 222 has a length L
₁ only needs to be able to insert the headrest insert 4 7
It is about 0 mm, and its end is located at a substantially middle point between the two cylinders. Specifically, assuming that the base width of the insert 4 having the reinforcing member 41 as shown in FIG. 9 is H [mm], the short plate length L ₁ [mm] is H ≦ L ₁ ≦ H + 25. It is within the range to meet. This short sheet length L _1, if the small projection 224 will be described later, is formed, this part also includes the length of forming (FIG. 2). Short plate height h is 5mm to 10mm
And lower than the cylinder height (FIG. 3). The thickness W of the short plate 222 is in the range of 0.2 mm to 2.0 mm, and more preferably 0.5 mm to 1.0 mm.
When the thickness W of the short plate 222 is large, the coating 3 having a large thickness is formed also at the leading edge of the short plate, and it is not only difficult to form the slit 11 for insert insertion,
This is because the opening of the slit becomes too open. On the other hand, when the thickness of the short plate 222 is small, there is a disadvantage that the short plate bends during slash molding. When the short plate 222 has a predetermined thickness and its tip edge is sharpened at an acute angle, it is suitable for forming the slit 11. Note that the columnar small protrusion 224 is integrally held at the end of the short plate 222. Small protrusion 22
The height of 4 is the same as that of the short plate 222, and the upper surface of the small projection 224 is also concavely curved like the cylindrical body 223.

Next, a method of manufacturing the headrest skin 1 by slush molding using the above-described mold 2 will be described. First, a plastic material having good fluidity such as a vinyl chloride resin paste (plastisol) or powdered polyethylene is charged into the cavity mold 21 of the mold 2, and the mold 2 is closed by the lid mold 22. Next, the mold 2 is placed in a heating furnace while rotating or swinging, and the mold 2 is heated. The plastic raw material flows along the cavity surface 2a by the rotation and swinging of the molding die 2, and becomes a molten state by heating and adheres substantially uniformly on the cavity surface 2a. At this time, the plastic raw material adheres also around the short plate 222, the cylindrical body 223, and the small protrusion 224. However, since the upper edge of the short plate 222 is in a sharpened state, there is little riding of the plastic raw material.
Only that portion becomes a thin molten film (FIG. 6A). Since the short plate 222 is in an upright state toward the inside of the mold, the method of transmitting heat by heating and the force of holding the plastic material under rotation and oscillation are weaker at the tip, and the molten film layer becomes thinner toward the tip. On the other hand, the upper surface of the cylindrical body 223 is curved and its peripheral edge is sharp, so that it is easy to radiate heat, and even if the plastic raw material tends to stagnate, it flows down and there is little riding, so that the molten film is formed. It becomes thin ((b) in FIG. 6). The small projections 224 also have substantially the same shape as the cylindrical body 223, and the molten film on the upper surface periphery of the small projections is thin.

Thereafter, the mold 2 is cooled to cure the molten plastic layer adhering to the cavity surface 2a, and the coating 3 is obtained by demolding. This film body 3 is shown in FIG.
The molten film adhered to the short plate 222 in the hollow shape as described above becomes the tongue piece 14 and forms the concave groove 31. Here, the coating portions 3a, 3b, 3c relating to the molten coating on the upper edge of the short plate 222 and the peripheral edge of the upper surface of the cylindrical body 223 and the small protrusion 224 are thinned (FIGS. 4, 6). These film portions 3a, 3
b and 3c form a separation line that opens with a slight force.

Next, post-processing of the film body 3 obtained by slush molding is performed. The film body 3 made by the slush molding is held in hand, and is expanded so as to push the entrance of the concave groove 31 as shown by the arrow in FIG. Then, the thickness of the film body 3 is small and the groove bottom 32 of the concave groove 31 having the weakest strength.
(Coating body part 3a) is opened linearly, and a slit 11 for insert insertion is formed (FIG. 7 (b)). Column 223
8b is also thin (FIG. 8).
(A)) Since it is easy to separate, the upper circular portion 33 is easily detached from the film body 3 and the insert insertion hole 12 is formed with the above expanding operation (FIG. 8 (B)). Groove 3
Since the peripheral edge of the upper surface of the groove bottom 32, the cylindrical body 223, and the small projection 224 is very thin, it can be cut by simply pushing with a finger without using a cutter, a cutting machine, or the like. Thus, the film body 3 is inserted into the slits 11 for inserting the inserts,
By forming the insert insertion hole 12, the headrest skin 1 is obtained.

Thereafter, an insert 4 as shown in FIG. 9 is inserted into the epidermis 1. The insert 4 is a plate-like reinforcing material 41
(For example, reinforcing plates, reinforcing bars, etc.) are bridged near the base. Since the slit length L [mm] is in the range of H ≦ L ≦ H + 25 with respect to the base width H [mm] of the insert 4, the insert 4 is inserted into the skin 1 using the slit 11. The slit length L is the short plate length L
₁ and L ₁ is H ≦ L ₁ ≦ H as described above.
This corresponds to being within the range satisfying +25. here,
Even if the slit length L is the same as the base width H of the insert, since the skin 1 is elongated, the insert can be inserted. On the other hand, if the slit length L exceeds the upper limit value (H + 25), problems such as leakage of the foaming material and opening of the mouth appear, so this value is set as the upper limit. However, the slit length L
[Mm] is L with respect to the outer diameter K [mmφ] of the injection head.
It is necessary to satisfy the condition of ≧ πK / 2 (see FIG. 9). Otherwise, even if the insert 4 can be inserted into the skin 1, the injection head does not enter the slit 11 well, and the foaming material cannot be injected into the skin. Then, both stays 4a, 4a of the insert are disposed outside the skin through the circular holes 12, 12, and the insert 4 is inserted and set in the skin 1. When the stay 4a is inserted into the cylindrical portion 15 formed by the cylindrical body 223, the insert 4
Is fixedly held. Note that the inner diameter of the cylindrical portion 15 is the stay diameter D.
If it is set smaller (here, about 9.0 mm to 9.5 mm), it is possible to improve the sealing property of the stay portion during foam molding, which is more preferable.

Next, the slit 11 is expanded by hand or the like, and the epidermis 1 is cut from the injection head (head outer diameter: Kmmφ) of the injection machine M.
A foaming raw material G (for example, a urethane raw material) is injected into the inside (FIG. 9). At the time of injection, the slit 11 has a small length and further has a tongue piece 14 to have a function of closing itself. Therefore, the foaming material G once injected does not overflow from the slit 11. By the way, in the conventional method, the foaming raw material was injected after placing the skin 1 in the foaming mold. Therefore, the slit 11 of the epidermis 1 did not open well, and was crushed by the nozzle of the injector M, and the epidermis 1 was deformed, which sometimes hindered the injection. Even if such a defect occurs, it is difficult to take countermeasures due to the inside of the mold. In this case, however, since the foaming material G is injected outside the mold, the slit can be easily opened by hand or the like, and even if the mouth closes, the correction process can be quickly performed. It can be implemented. Since the skin 1 is in the shape of a bag, it has a force to maintain the shape of the skin, and contributes to smooth work outside the mold.
Thus, the injection of the predetermined amount of the foaming raw material G into the skin 1 is completed.

Thereafter, these are set in the foaming mold T. Then, the mold is closed and the cushion material 5 is formed by foam molding (FIG. 10). A tongue piece 14 seals the slit 11,
Further, in the foam molding process, the sealing of the slit is performed by applying a foaming pressure for closing the slit 11 from both sides of the tongue pieces 14 and 14. After foaming and curing, the mold is removed, and a desired headrest A in which the skin 1, the insert 4, and the cushion material 5 are integrated is obtained.

According to the method for manufacturing such a headrest, the slit length L is set to satisfy H ≦ H in accordance with the base width H of the insert 4.
By setting the range of L ≦ H + 25, it is possible to insert the insert into the epidermis, and at the same time, it is possible to inject the foaming material into the epidermis by the injection head. Since the size is reduced, the appearance is good, and the opening at the time of foam molding is less likely to occur. Further, the small plate thickness W of the short plate 222 narrows the slit width, and when the headrest is formed by foam molding of the skin and the insert integrally, the opening is more unlikely to occur. In addition, since the tongue piece 14 surrounding the narrow opening of the slit 11 is provided, the opening of the slit 11 is more securely closed by foaming pressure from both sides at the time of foam molding, so that the foaming raw material is out of the slit. Prevent spills. Therefore, leakage of the foaming material during foam molding can be prevented without using a sheet material as in the related art. By eliminating the need for sheet material, cost reduction can be achieved. On the other hand, since the tongue piece 14 plays a role of a wall against the intrusion of the slit opposing edge, a biting defect (see FIG. 14 (b)) which causes the step β seen in the conventional product does not occur. And not only the slit 11 but also the circular hole 12
Are the groove bottom 32 of the concave groove 31 relating to the film body 3 and the cylindrical body 223.
Is very thin, so that it can be cut without bending or warping by simply pushing with a finger without using a cutter, a cutting machine, etc., and the appearance is improved. Therefore, the process of providing the slit 11 and the circular hole 12 for inserting the insert is greatly simplified, which contributes to reduction in the number of processing steps and stable maintenance of quality. In this embodiment, as shown in FIG. 9, a reinforcing plate is used as the insert 4. The insert 3 has a reinforcing member 41 such as a reinforcing rod and a base width H larger than the stay diameter. And, for example, an insert 4 as shown in FIG.

(2) Embodiment 2 In this embodiment, a rod-like body 4 made of a pipe or the like as shown in FIG.
This is a method for manufacturing a headrest using an insert 4 obtained by simply bending an insert 2. A cylindrical portion 15, which inserts and holds the stay 4a, into the skin 1 of the headrest A so that the insert can be easily inserted into the skin 1 corresponding to the insert shape.
A slit 11 is provided in a substantially intermediate area of the reference numeral 15. FIG. 11 shows a molding die 2 ′ relating to the skin 1. The molding die 2 ′ corresponds to the molding die 2 of FIG. 1, and here, two cylindrical bodies 223 and 213 for stay insertion are provided on the cavity surface 2 a of the lid die 22.
223 are provided, and a short plate 225 for forming a slit is erected in an intermediate region connecting these cylinders as shown in the figure. still,
Small projections 224 as in the first embodiment are not provided at both ends of the short plate 225. The short plate length L ₂ [mm] is πK / 2 ≦ L ₂ ≦ (πK /
2) Within the range of +25. This short plate length L ₂ corresponds to the slit length L when the skin 1 is made from the film body 3,
The slit length L falls within the range of πK / 2 ≦ L ≦ (πK / 2) +25. The slit length L is πK as the minimum value
With the value of / 2, not only the insert 4 can be inserted into the skin 1 but also the foaming material can be injected into the skin by the injection head. On the other hand, the slit length L is set to the upper limit (πK /
2) When the value exceeds +25, defects such as leakage of the foaming material and opening of the mouth appear. Therefore, as the slit length L, πK
/ 2 ≦ L ≦ (πK / 2) +25. Note that, of course, K [mmφ] ≧ D [mm
φ] is a requirement. In the present embodiment, a gas vent hole 226 is provided in the lid mold 22. In the case where a foaming agent is contained in the plastic raw material for forming the skin 1 by slush molding, the foaming agent is foamed and adheres to the cavity surface 2a in a layered manner.
Here, in the molding die 2 in a closed state, the internal pressure of the molding die 2 is further increased by the foaming gas due to the expansion of the air in the molding due to heating, and the lid 22 of the molding die 2 is often pushed up to form a gap. . As a result, there arises a problem that the plastic raw material is extruded into the gap and becomes clogged, or a cavity shape becomes larger than its original size. For this reason, in this case, the air in the mold expanded by heating and the foaming gas generated by foaming are discharged to the outside of the mold 2 ′ through the gas vent hole 226. Since the pressure in the mold 2 'does not increase, the lid 22 of the mold is not pushed up. Therefore, it can be manufactured without causing burrs on the skin 1 having a regular shape and dimensions. Other configurations and operations are the same as those of the first embodiment.

In the method of manufacturing the headrest, first, after forming the film, the slit 11 and the circular hole 12 are opened. The slit length L is πK / 2 ≦ L ≦ with respect to the outer diameter K of the injection head.
(ΠK / 2) +25. Next, the slit 11 is opened, an insert is inserted, and after the insertion, the foaming raw material G is injected into the epidermis. After injecting a predetermined amount of the foaming material into the skin, these are set in the foaming mold T. Then, foam molding is performed to form the cushion material 5 integral with the skin to obtain a desired headrest A.

The manufacture of such a headrest can be achieved by inserting the insert 4 into the skin even if the slit length L is shortened within the above-mentioned range for the insert 4 in which the rod 42 is bent in a U-shape. And the injection of the foaming material into the epidermis is not hindered. Then, an effect similar to that of the first embodiment is obtained.

In the present invention, the present invention is not limited to those shown in the above embodiments, but can be variously changed within the scope of the present invention depending on the purpose and application. The size, shape, material, and the like of the skin 1, the insert 4, the cushion material 5, and the like can be appropriately selected. In the embodiment, the slit 11 and the circular hole 12 are formed by the expanding operation for expanding the mouth of the concave groove 31. Instead, the slit 11 and the circular hole 12 are pushed by pushing the groove bottom of the concave groove 31 to form the slit 11 and the circular hole 12. It may be formed. The formation of the film body 3 at the stage before the skin 1 can also be performed by rotation molding.

[0025]

As described above, the method for manufacturing a headrest according to the present invention eliminates problems such as leakage of foaming material from a slit, opening of a mouth, and a step by eliminating the need for a material such as a sheet material. It also has excellent effects such as improved quality.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a molding die for a headrest skin in a first embodiment.

FIG. 2 is a longitudinal sectional view of FIG.

FIG. 3 is a partially enlarged perspective view around a short plate.

FIG. 4 is an overall vertical cross-sectional view of a film formed by a molding die in FIG. 1;

FIG. 5 is a perspective view of a film body.

FIG. 6 is a partially enlarged cross-sectional view around a cylindrical body and around a short plate in FIG. 4;

FIG. 7 is a cross-sectional view showing a state change in which a slit is formed.

FIG. 8 is a cross-sectional view showing a state change in which a circular hole is formed.

FIG. 9 is a partial cross-sectional perspective view in which an insert is inserted into a skin.

FIG. 10 is a cross-sectional view showing a state in which these are set in a foaming mold after foaming raw materials have been injected into the skin, and foam molding has been completed.

FIG. 11 is an overall perspective view of a molding die for a headrest skin in Example 2.

FIG. 12 is a partial cross-sectional perspective view of a headrest according to a second embodiment.

FIG. 13 is a perspective view of a prior art showing insertion of an insert into an epidermis.

FIG. 14 is a longitudinal sectional view showing a problem of a headrest according to the related art.

[Explanation of symbols]

 Reference Signs List 1 skin 11 slit 12 circular hole 2, 2 mold 2a cavity surface 222 short plate 223 cylindrical body 225 short plate 31 concave groove 32 groove bottom 4 insert 42 rod-shaped body 5 cushion material A headrest D outer diameter G foaming material H base width L Slit length T foam type

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 31:58 (72) Inventor Akinori Teranishi 3-36 Imaikecho, Anjo-shi, Aichi Pref. Inoac Corporation Anjo Works (56) References JP-A-8-230075 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 41/20 B29C 41/04 B29C 41/18 B29D 31/00

Claims (5)

(57) [Claims] 1. A method for manufacturing a headrest in which an insert is inserted into a bag-shaped skin by slush molding or rotation molding, and a foaming material is injected into the skin to perform foam molding integrally with the skin. The body body was erected and the coating body related to the skin was formed using a mold having a short plate erected from one of the cylinders as a starting point toward the other cylinder, and after molding, the short plate was formed. The groove is expanded or pushed to provide a slit at the bottom of the groove, and at the same time, the coating formed on the tip end surface of the cylindrical body is removed to form a circular hole to complete the skin first, and then the insert is inserted into the skin. And the both stays of the insert are arranged outside the skin through the circular hole, and then a foaming material is injected into the skin through the slit to form a cushion material integral with the skin by foam molding. Method of manufacturing a Ddoresuto. 2. The method according to claim 1, wherein a length L [mm] of the slit satisfies the following expression with respect to a base width H [mm] of the insert. H ≦ L ≦ H + 25 (where L ≧ πK / 2) Here, K indicates the outer diameter of an injection head for injecting the foaming material into the skin, and the unit thereof is [mmφ]. 3. A method for manufacturing a headrest in which an insert is inserted into a bag-shaped skin by slush molding or rotation molding, and a foaming material is injected into the skin to perform foam molding integrally with the skin. The body body is erected and the coating body relating to the skin is formed using a molding tool having a short plate erected also in the middle area connecting the two cylinders, and after molding, the groove formed by the short plate is expanded. Alternatively, a slit is provided at the groove bottom of the concave groove and the coating formed on the tip end surface of the cylindrical body is removed to form a circular hole to complete the skin first, and thereafter, an insert is inserted into the skin and A method of manufacturing a headrest, wherein both stays of an insert are arranged outside the skin through the circular holes, and then a foaming material is injected into the skin through the slits to form a cushion material integral with the skin by foam molding. 4. The insert is formed by bending a rod-shaped body into a U-shape, and has a length L of the slit with respect to an outer diameter K [mmφ] of an injection head for injecting a foaming material into an epidermis. The method for manufacturing a headrest according to claim 3, wherein [mm] satisfies the following expression. πK / 2 ≦ L ≦ (πK / 2) +25 5. The method according to claim 1, wherein after inserting the insert into the skin, a predetermined amount of a foaming material is injected from the slit, and thereafter, these are set in a foaming mold and foamed. Headrest manufacturing method.