FOAMING DIE DEVICE ADAPTED TO EFFECT FOAMING IN TRIM COVER ASSEMBLY INTEGRALLY TO FORM HEADREST, AND FOAMING PROCESS FOR FORMING HEADREST BY EFFECTING FOAMING IN TRIM COVER ASSEMBLY INTEGRALLY, USING THE FOAMING DIE DEVICE

Abstract

A foaming die device for forming a headrest is provided, which comprises a lower die having a first protrusion and an upper die having a second protrusion. The lower and upper dies are used for accommodating a trim cover assembly with a headrest stay portion extending outwardly through a stay passage hole formed in the trim cover assembly. The first and second protrusions are adapted to press and turn over a projected area created about the stay passage hole into the inside of that trim cover assembly. Also, a foaming process for forming the headrest, using this foaming die device, is provided, in which the projected area is turned over by the first and second protrusions into the trim cover assembly when placing the trim cover assembly in the dies. Hence, conventional preliminary steps using cylindrical stick to turn over the projected area into the trim cover assembly are eliminated.

Claims

1. A foaming process for forming a headrest, comprising the steps of: providing a foaming device comprising: a lower die having a first cavity region defined therein; an upper die having a second cavity region defined therein; said lower and upper dies being able to be mated with and separated from each other, wherein, when the lower and upper dies are mated with each other, a cavity is defined between said first and second cavity regions; a first protrusion provided in said lower die so as to protrude in a direction from an inner wall of the lower die towards said first cavity region; and a second protrusion provided in said upper die so as to protrude in a direction from an inner wall of the upper die towards said second cavity region; providing a headrest stay having at least one stay portion extending therefrom; providing a trim cover assembly having at least one stay passage hole adapted to allow said at least one stay portion to pass therethrough; wherein said at least one stay portion is so dimensioned to contact an end of said at least one stay passage hole, installing said headrest stay within said trim cover assembly, such that said at least one stay portion of the headrest stay passes through said at least one stay passage hole and extends outward from the trim cover assembly, in a sliding, close contact with said end of said at least one stay passage hole, thus causing concurrent stretching of said end of said at least one stay passage hole in an outward direction of the trim cover assembly and resulting in creation of a projected area in said end, said projected area protruding outward from said at least one stay passage hole and being laid on and about a part of the at least one stay portion located exteriorly of the trim cover assembly, so that the projected area is exposed outside of the trim cover assembly; loading said trim cover assembly with said headrest stay thus installed therein into either of said lower and upper dies; causing said lower and upper dies to mate together to define said cavity between said first and second cavity regions, with said trim cover assembly being accommodated in the cavity, such that said first and second protrusions are pressed against said projected area towards said at least one stay passage hole and forcibly inserted into between said at least one stay portion and said at least one stay passage hole, to the extent that the first and second protrusions are entered into the inside of the trim cover assembly, thereby causing the projected area itself to turn over at the first and second protrusions in relation to said at least one stay passage hole, thus resulting in reverse folding of the projected area from the at least one stay passage hole into the inside of said trim cover assembly on and along the first and second protrusions being entered into the inside of the trim cover assembly, whereby an entirety of the thus-turned-over projected area is displaced to the inside of the trim cover assembly together with the first and second protrusions, as a result of which, said entirety of the turned-over projected area is positioned within the trim cover assembly and also laid on the first and second protrusions entered in the trim cover assembly; thereafter, injecting a liquid foaming agent into the inside of said trim cover assembly and curing said liquid foaming agent into an increased mass of foam padding filled in the trim cover assembly, so that said turned-over projected area is sandwiched between said foam padding and both said first and second protrusions, within the trim cover assembly, whereupon a headrest with said at least one stay portion exposed outside thereof is formed in said cavity; and removing said headrest from said cavity by separating said lower and upper dies, during which, said first and second protrusions, provided in the lower and upper dies, respectively, are both automatically withdrawn outwards through between said at least one stay portion and said turned-over projected area secured to said foam padding and are eventually removed from said at least one stay passage hole, thereby producing a resultant headrest in which said turned-over projected area is retained inside of the resultant headrest, while said at least one stay portion is exposed outside of the resultant headrest.

2. The foaming process according to claim 1, wherein each of said first and second protrusions is provided with: a distal end adapted to face said cavity; and a thickness that becomes small as it proceeds to said distal end, thereby not only facilitating insertion of said first and second protrusions into between said at least one stay passage hole and said at least one stay portion, but also facilitating said reverse folding of said projected area, at said step of causing said lower and upper dies to mate together.

3. The foaming process according to claim 1, wherein each of said first and second protrusions is provided with a toothed end portion that is to face said cavity, said toothed end portion being adapted to reduce a coefficient of friction thereof against said projected area and said at least one stay passage hole, thereby not only facilitating insertion of said first and second protrusions into between said at least one stay passage hole and said at least one stay portion, but also facilitating said reverse folding of said projected area, at said step of causing said lower and upper dies to mate together.

4. A foaming process for forming a headrest, comprising the steps of: providing a foaming device comprising: a lower die including: a first cavity region; a first mating surface; and a first stay receiving recession formed in said first mating surface; an upper die including: a second cavity region; a second mating surface adapted to be mated with said first mating surface; and a second stay receiving recession formed in said second mating surface; said upper and lower dies being able to be mated with and separated from each other, wherein, when the upper and lower dies are mated with each other, a cavity is defined between said first and second cavity regions; a first protrusion provided in said lower die at said first mating surface so as to protrude in a direction from an inner wall of the lower die towards said first cavity region, said first protrusion having a first recession communicating with said first stay receiving recession; and a second protrusion provided in said upper die at said second mating surface so as to protrude in a direction from an inner wall of the upper die towards said second cavity region, said second protrusion having a second recession communicating with said second stay receiving recession; providing a headrest stay having at least one stay portion extending therefrom; providing a trim cover assembly having at least one stay passage hole adapted to allow said at least one stay portion to pass therethrough; wherein said at least one stay portion is so dimensioned to contact an end of said at least one stay passage hole, installing said headrest stay within said trim cover assembly, such that said at least one stay portion of the headrest stay passes through said at least one stay passage hole and extends outward from the trim cover assembly, in a sliding, close contact with said end of said at least one stay passage hole, thus causing concurrent stretching of said end of said at least one stay passage hole in an outward direction of the trim cover assembly and resulting in creation of a projected area in said end, said projected area protruding outward from said at least one stay passage hole and being laid on and about a part of said at least one stay portion located exteriorly of the trim cover assembly, so that said projected area is exposed outside of the trim cover assembly; loading said trim cover assembly with said headrest stay thus installed therein into either of said lower and upper dies; placing said at least one stay portion in either of said first and second stay receiving recessions as well as in either of said first and second recessions; causing said lower and upper dies to mate together to define said cavity between said first and second cavity regions, with said trim cover assembly being accommodated in the cavity, while said first and second mating surfaces are mated with each other to cause mating of said first and second protrusions together, whereby said first and second stay receiving recessions are mated with each other, thereby embracingly receiving one part of said at least one stay portion therebetween, whereas at the same time, said first and second recessions are mated with each other, thereby embracingly receiving the other part of said at least one stay portion therebetween, such that the thus-mated first and second protrusions are pressed against said projected area towards said at least one stay passage hole and forcibly inserted into between said at least one stay portion and said at least one stay passage hole, to the extent that the mated first and second protrusions are entered into the inside of the trim cover assembly, thereby causing the projected area itself to turn over at the mated first and second protrusions in relation to said at least one stay passage hole, thus resulting in reverse folding of the projected area from the at least one stay passage hole into the inside of said trim cover assembly on and along the mated first and second protrusions being entered into the inside of the trim cover assembly, whereby an entirety of the thus-turned-over projected area is displaced to the inside of the trim cover assembly together with the mated first and second protrusions, as a result of which, said entirety of the turned-over projected area is positioned within the trim cover assembly and laid on and about the mated first and second protrusions entered in the trim cover assembly; thereafter, injecting a liquid foaming agent into the inside of said trim cover assembly and curing said liquid foaming agent into an increased mass of foam padding filled in the trim cover assembly, so that said turned-over projected area is sandwiched between the foam padding and the mated first and second protrusions, within the trim cover assembly, whereupon a headrest with said at least one stay portion exposed outside thereof is formed in said cavity; and removing said headrest from said cavity by separating said lower and upper dies, during which, said first and second protrusions, provided in the lower and upper dies, respectively, are both automatically withdrawn outwards through between said at least one stay portion and said turned-over projected area secured to said foam padding and are eventually removed from said at least one stay passage hole, thereby producing a resultant headrest in which said turned-over projected area is retained inside of the resultant headrest, while said at least one stay portion is exposed outside of the resultant headrest.

5. The foaming process according to claim 4, wherein each of said first and second protrusions is provided with: a distal end adapted to face said cavity; and a thickness that becomes small as it proceeds to said distal end thereof, thereby not only facilitating insertion of said mated first and second protrusions into between said at least one stay passage hole and said at least one stay portion, but also facilitating said reverse folding of said projected area, at said step of causing said lower and upper dies to mate together.

6. The foaming process according to claim 4, wherein each of said first and second protrusions is provided with a toothed end portion that is to face said cavity, said toothed end portion being adapted to reduce a coefficient of friction thereof against said projected area and said at least one stay passage hole, thereby not only facilitating insertion of said mated first and second protrusions into between said at least one stay passage hole and said at least one stay portion, but also facilitating said reverse folding of said projected area, at said step of causing said lower and upper dies to mate together.

7. A foaming process for forming a headrest, comprising the steps of: providing a foaming device comprising: a lower die having a first cavity region defined therein; an upper die having a second cavity region defined therein; said upper and lower dies being able to be mated with and separated from each other, wherein, when the upper and lower dies are mated with each other, a cavity is defined between said first and second cavity regions; a first substantially-semi-cylindrical protrusion provided in said lower die so as to protrude in a direction from an inner wall of the lower die towards said first cavity region; and a second substantially-semi-cylindrical protrusion provided in said upper die so as to protrude in a direction from an inner wall of the upper die towards said second cavity region; providing a headrest stay having at least one substantially-columnar stay portion extending therefrom; providing a trim cover assembly having at least one substantially-circular stay passage hole adapted to allow said at least one substantially-columnar stay portion to pass therethrough; wherein said at least one substantially-columnar stay portion is so dimensioned to contact an entire end of said at least one substantially-circular stay passage hole, wherein said first and second substantially-semi-cylindrical protrusions are able to be mated with each other to embracingly receive said at least one substantially-columnar stay portion therebetween, installing said headrest stay within said trim cover assembly, such that said at least one substantially-columnar stay portion of the headrest stay passes through said at least one substantially-circular stay passage hole and extends outward form the trim cover assembly, in a sliding, close contact with said entire end of said at least one substantially-circular stay passage hole, thus causing concurrent stretching of said entire end of said at least one substantially-circular stay passage hole in an outward direction of the trim cover assembly and resulting in creation of a cylindrically projected area in said entire end, said cylindrically projected area protruding outward from said at least one substantially-circular stay passage hole and being laid on and about a part of the at least one substantially-columnar stay portion located exteriorly of the trim cover assembly, so that said cylindrically projected area is exposed outside of the trim cover assembly; loading said trim cover assembly with said headrest stay thus installed therein into either of said lower and upper dies; causing said lower and upper dies to mate together to define said cavity between said first and second cavity regions, with said trim cover assembly being accommodated in said cavity, while said first and second substantially-semi-cylindrical protrusions, provided in said lower and upper dies, respectively, are automatically mated with each other, thereby embracingly receiving said at least substantially-columnar stay portion therebetween, such that the thus-mated first and second substantially-semi-cylindrical protrusions are pressed against an entirety of said cylindrically projected area towards said at least one substantially-circular stay passage hole and forcibly inserted into between said at least one substantially-columnar stay portion and said at least one substantially-circular stay passage hole, to the extent that the mated first and second substantially-semi-cylindrical protrusions are entered into the inside of the trim cover assembly, thereby causing the cylindrically projected area itself to turn over at the mated first and second substantially-semi-cylindrical protrusions in relation to said at least one substantially-circular stay passage hole, thus resulting in reverse folding of said cylindrically projected area from the at least one substantially-circular stay passage hole into the inside of said trim cover assembly on and along the mated first and second substantially-semi-cylindrical protrusions being entered into the inside of the trim cover assembly, whereby an entirety of the thus-turned-over cylindrically projected area is displaced to the inside of the trim cover assembly together with the mated first and second substantially-semi-cylindrical protrusions, as a result of which, said entirety of the turned-over cylindrically projected area is positioned within the trim cover assembly and laid on and about the mated first and second substantially-semi-cylindrical protrusions entered in the trim cover assembly; thereafter, injecting a liquid foaming agent into the inside of said trim cover assembly and curing said liquid foaming agent into an increased mass of foam padding filled in the trim cover assembly, so that the thus-turned-over cylindrically projected area is sandwiched between the foam padding and the mated first and second substantially-semi-cylindrical protrusions, within the trim cover assembly, whereupon a headrest with said at least one substantially-columnar stay portion exposed outside thereof is formed in said cavity; and removing said headrest from said lower and upper dies by separating said lower and upper dies, during which, said first and second substantially-semi-cylindrical protrusions, provided in the lower and upper dies, respectively, are both automatically withdrawn outwards through between said at least one substantially-columnar stay portion and said turned-over cylindrically projected area secured to said foam padding and are eventually removed from the at least one substantially-circular stay passage hole, thereby producing a resultant headrest in which said turned-over cylindrically projected area is retained inside of the resultant headrest, while said at least one substantially-columnar stay portion is exposed outside of the resultant headrest.

8. The foaming process according to claim 7, wherein each of said first and second substantially-semi-cylindrical protrusions is provided with: a distal end adapted to face said cavity; and a thickness that becomes small as it proceeds to said distal end thereof, thereby not only facilitating insertion of said mated first and second substantially-semi-cylindrical protrusions into between said at least one substantially-circular stay passage hole and said at least one substantially-columnar stay portion, but also facilitating said reverse folding of said cylindrically projected area, at said step of causing said lower and upper dies to mate together.

9. The foaming process according to claim 7, wherein each of said first and second substantially semi-cylindrical protrusions is provided with a toothed end portion that is to face said cavity, said toothed end portion being adapted to reduce a coefficient of friction thereof against said cylindrically projected area and said at least one substantially-circular stay passage hole, thereby not only facilitating insertion of said mated first and second substantially-semi-cylindrical protrusions into between said at least one substantially-circular stay passage hole and said at least one substantially-columnar stay portion, but also facilitating said reverse folding of said cylindrically projected area, at said step of causing said lower and upper dies to mate together.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a partly broken perspective view of a headrest which is formed by a foaming die device in accordance with the present invention;

[0034] FIG. 2 is a sectional view showing one exemplary mode of the foaming die device;

[0035] FIG. 3 is a partly broken perspective view showing a stay receiving element provided in a lower die of the foaming die device;

[0036] FIG. 4 is a fragmentary sectional view showing the stay receiving element provided in the lower die;

[0037] FIG. 5 is a sectional view showing a state where a trim cover assembly is placed in upper and lower dies of the foaming die device;

[0038] FIG. 6 is a sectional view showing a state where a liquid foaming agent has been injected and cured in the trim cover assembly placed in the upper and lower dies;

[0039] FIG. 7 is a partly broken perspective view showing another mode of stay receiving element provided in the lower die of the foaming die device; and

[0040] FIG. 8 is a fragmentary sectional view showing such another mode of stay receiving element provided in the lower die.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

[0041] FIG. 1 shows a resulting headrest HR formed under a foaming process in accordance with the present invention. The headrest HR has: a trim cover assembly 2 formed by sewing several cover materials together in a bag-like three-dimensional shape; a foam padding 3 which is formed in the trim cover assembly 2 under the steps of injecting a liquid foaming agent (e.g. a liquid urethane material capable of being foamed) into the inside of the trim cover assembly 2 and then curing the liquid foaming agent to form an increased mass of the foam padding 3 filled in the trim cover assembly; and a headrest stay 5 securely provided within the foam padding 3.

[0042] While not shown clearly, the trim cover assembly 2, which forms a surface cover of the headrest, is of a two-layer lamination construction consisting of: a top cover member made of an unbreathable, impermeable synthetic leather material; and a foam wadding affixed on the reverse surface of that top cover member, the foam wadding being made of a slab urethane foam material. The headrest stay 5 is formed in a substantially U configuration which has: a substantially U-shaped body portion 5c embedded in the foam padding 3; and a pair of substantially-rectilinear stay portions 5a and 5b (which shall hereinafter be referred to as a first substantially-rectilinear stay portion 5a and a second substantially-rectilinear stay portion 5b, respectively). As seen in FIG. 1, in the bottom wall 2c of the trim cover assembly 2, there are formed a pair of stay passage holes 2a and 2b (which shall hereinafter be referred to as a first stay passage hole 2a and a second stay passage hole 2b, respectively). The first and second substantially-rectilinear stay portions 5a and 5b are shown as passing through the first and second stay passage holes 2a and 2b, respectively, and being exposed exteriorly of the trim cover assembly 2.

[0043] FIG. 2 shows a foaming die device 1 by which the trim cover assembly 2 with the headrest stay 5 installed therein as stated above can be subjected to foaming in integral manner. By use of such foaming die device 1, the above-described headrest HR is formed. This foaming die device 1 comprises an upper die 20 and a lower die 10. The upper and lower dies 20 and 10 are hingedly connected by a hinge 6 with each other, so that the upper die 20 can be moved away from the lower die 10 to open the foaming die device 1 and mated therewith to close the latter 1. As shown, each of the upper and lower dies 20 and 10 has a cavity region defined therein, and therefore, when the upper and lower dies 20 and 10 are mated with each other, a cavity C is defined therebetween. The cavity C is so configured to accommodate an entirety of the trim cover assembly 2 therein. The upper die 10 has a first mating surface 10a, whereas the upper die 20 has a second mating surface 20a. When mating the upper die 20 with the lower die 10 to close the foaming die device 1, such two mating surfaces 10a and 20a are mated and contacted with each other closely. The lower die 10 is provided with a first stay receiving element 30 in the first mating surface 10a thereof, wherein the first stay receiving element 30 is so configured to receive a part of lower half of the substantially-rectilinear stay portion of the headrest stay 5. On the other hand, the upper die 20 is provided with a second stay receiving element 40 in the second mating surface 20a thereof, wherein the second stay receiving element 40 is so configured to embracingly overlie a part of upper half of the substantially-rectilinear stay portion of the headrest stay 5.

[0044] As best shown in FIGS. 3 and 4, the first stay receiving element 30 is fixedly secured by securing screws 11 to the lower die 10. Specifically, the lower die 10 is formed with a recession 10b of semicircular cross-section, whereas the first stay receiving element 30 has a first semi-cylindrical main portion 30a defined therein. The first semi-cylindrical main portion 30a is secured fit in the recession 10b of the lower die 10. Further, the first stay receiving element 30 has a semi-cylindrical protrusion 30b. This semi-cylindrical protrusion 30b is shown as protruding in a direction from an inner wall 12 of the lower die 10 towards the cavity region of the lower die 10 which forms one of the cavity C. As will be described later, by means of such semi-cylindrical protrusion 30b, a cylindrically projected area A created from and about each of the first and second stay passage holes 2a and 2b can be forcibly turned over into the inside of the trim cover assembly 2.

[0045] As shown, the first semi-cylindrical main portion 30a is received in the recession 10b and fixedly secured thereto by two securing screws 11 and 11.

[0046] Prior to a foaming process using the foaming die device 1, while not shown, there are the steps of providing a hollow trim cover assembly 2 with the headrest stay 5 installed therein, such that both first and second substantially-rectilinear stay portions 5a and 5b of the headrest stay 5 project outwardly from the trim cover assembly 2. In such preliminary steps, as normally done in the art, a worker inserts the first substantially-rectilinear stay portion 5a into the second stay passage hole 2b of the trim cover assembly 2 and then manages to continue on pushing that first substantially-rectilinear stay portion 5a, via the second stay passage hole 2b, into the inside of the trim cover assembly 2 and causing that stay portion 5a to advance within the trim cover assembly 2 towards the first stay passage hole 2a, so that the first substantially-rectilinear stay portion 5a projects outwardly from the trim cover assembly 2 through the second stay passage hole 2b, while ascertaining that the second substantially-rectilinear stay portion 5b passes through and yet remains in the earlier-stated first stay passage hole 2a. In that way, the headrest stay 5 is installed within the trim cover assembly 2 which is hollow inside thereof at this stage, such that both first and second substantially-rectilinear stay portions 5a and 5b thereof are exposed exteriorly of the trim cover assembly. It is noted here that the first and second substantially-rectilinear stay portions 5a and 5b are closely contacted with the first and second stay passage holes 2a and 2b, respectively. Therefore, as previously stated in the description of prior art, at the above-described step of pushing the first and second substantially-rectilinear stay portions 5a and 5b outwardly through the first and second stay passage holes 2a and 2b, respectively, it is inevitable that both two peripheral edges respective of those first and second stay passage holes 2a and 2b are forcibly stretched in a direction outwardly of the trim cover assembly 2. As a result thereof, a cylindrically projected area is created from and about each of the first and second stay passage holes 2a and 2b. In other words, a pair of such cylindrically projected areas respective of the two stay passage holes 2a and 2b are laid on and about the two substantially-rectilinear stay portions 5a and 5b, respectively, thus projecting outwardly of the trim cover assembly 2. Such two cylindrically projected areas can be recognized by the designations A and A in the drawings.

[0047] Next, the above-stated hollow trim cover assembly 2 with the two cylindrically projected areas A and A exposed exteriorly thereof is placed in the cavity region of the lower die 10, wherein the cavity region forms one of the cavity C as stated earlier. At this point, the first semi-cylindrical protrusion 30b, which protrudes in a direction from the inner wall 12 to the cavity region of the lower die 10, enters the first stay passage hole 2a. Consequently, as will be elaborated later, the cylindrically projected area A, created about the first stay passage hole 2a and exposed exteriorly of the trim cover assembly 2, is pressed by that first semi-cylindrical protrusion 30b, so that the cylindrically projected area A is forcibly turned over relative to the stay passage hole 2a into the inside of the trim cover assembly 2.

[0048] The first stay receiving element 30 has: a first stay receiving recession 30c of semi-circular cross-section, which is adapted to receive the first substantially-rectilinear stay portion 5a of the headrest stay 5; and a pair of mating surfaces 30d and 30d defined flush with the first mating surface 10a of the lower die 10, wherein such pair of mating surfaces 30d are situated on the opposite sides of and symmetrically relative to the first stay receiving recession 30c, as shown.

[0049] The first semi-cylindrical protrusion 30b is tapered or so formed to become mailer in thickness as it proceeds to the distal end thereof. This first semi-cylindrical protrusion 30b has: a first extension surface region B which forms one local area of first and second surfaces 30A that define the first stay receiving recession 30c therein; and a curved surface F which is defined in the undersurface of the first extension surface region B so as to coverage from the outer surface of the semi-cylindrical protrusion 30b towards the distal end thereof. Such curved surface F functions to cause the cylindrically projected area A to turn over curvilinearly therealong in a direction to the inside of the trim cover assembly 2, as will be described later.

[0050] Although not shown, a pair of the aforementioned first stay receiving elements 30 and 30 are actually provided in the first mating surface 10a of the lower die 10, such that one thereof is situated on the left, while the other thereof situated on the right. In other words, the left- and right-side first stay receiving elements 30 and 30 are provided in the lower die 10. It is to be understood that the right-side first stay receiving element 30 is so configured to receive a part of lower half of the first substantially-rectilinear stay portion 5a, whereas the left-side first stay receiving element 30 so configured to receive a part of lower half of the second substantially-rectilinear stay portion 5b. Also, though not shown, a pair of the aforementioned second stay receiving elements 40 and 40 are actually provided in the second mating surface 20a of the upper die 20, such that one thereof is situated on the left, while the other thereof situated on the right. In other words, the left- and right-side second stay receiving elements 40 and 40 are provided in the upper die 20. It is to be understood that the right-side second stay receiving element 40 is so configured to embracingly overlie a part of upper half of the first substantially-rectilinear stay portion 5a, whereas the left-side first stay receiving element 40 so configured to embracingly overlie a part of lower half of the second rectilinear stay portion 5b. Hence, it is to be understood that, when mating the upper die 20 with the lower die 10, the first substantially-rectilinear stay portion 5a is partly sandwiched between the right-side first and second stay receiving elements 30 and 40, whereas the second substantially-rectilinear stay portion 5b partly sandwiched between the left-side first and second stay receiving elements 30 and 40.

[0051] With regard to the second stay receiving element 40, any further detailed description is omitted as to its second stay receiving recession 40c, second semi-cylindrical main portion 40a, and second semi-cylindrical protrusion 40b having a second extension surface region D, since this second stay receiving element 40 is identical in shape and structure to the first stay receiving element 30. (See FIG. 2)

[0052] A description will be made of a process for forming a headrest HR by use of the foaming die device 1. As shown in FIG. 2, the upper die 20 is moved away from the lower die 10 to open the foaming die device 1. Thereafter, as seen in FIG. 5, a hollow trim cover assembly 2 with the headrest stay 5 installed therein as described earlier is placed and set in a cavity C defined between the two cavity regions of the upper and lower dies 20 an 10. This is a closed state of the foaming die device 1, in which the upper die 20 is mated with the lower die 10. But, prior thereto, it is to be understood that the two cylindrically projected areas A and A have been created from and about the first and second stay passage holes 2a and 2b of the trim cover assembly 2, respectively, thus projecting outwardly of the trim cover assembly 2, due to the reasons stated previously, and that, when placing the trim cover assembly 2 in the cavity region of the lower die 10, a worker should first press the bottom wall 2c of the trim cover assembly 2 against the left- and right-side first semi-cylindrical protrusions 30b and 30b and then place two lower half regions respective of the first and second rectilinear stay portions 5a and 5b of the headrest stay 5 in the right- and left-side first stay receiving recessions 30c and 30c of the lower die 10, respectively.

[0053] While not shown, at this stage, when the worker presses the trim cover assembly's bottom wall 2c against the inner wall of the lower die 10 towards the afore-said pair of first semi-cylindrical protrusions 30b and 30b, it is to be understood that the two first semi-cylindrical protrusions 30b and 30b are inserted into the first and second stay passage holes 2a and 2b, respectively, which in turn causes the two lower halves of the afore-said two cylindrically projected areas A and A to turn over relative to those two holes 2a and 2b, respectively, with the result that all the two lower halves of the two cylindrically projected areas A and A are entirely folded into the inside of the trim cover assembly 2 and positioned therein. Thereafter, it is to be understood that the worker moves the upper die 20 towards the lower die 10 in which the trim cover assembly 2 has been placed as above, in such a way that the inner wall of the upper die 20, where the left- and right-side second semi-cylindrical protrusions 40b and 40b exist, comes to contact with the bottom wall 2c of the trim cover assembly 2.

[0054] At this point, though not shown, as the inner wall of the upper die 20 comes to contact with the bottom wall 2c of the trim cover assembly 2, it is to be understood that the right- and left-side second semi-cylindrical protrusions 40b and 40b are inserted into the first and second stay passage holes 2a and 2b, respectively, which in turn causes two upper halves respective of the two cylindrically projected areas A and A to turn over in relation to those two holes 2a and 2b, respectively, with the result that all the two upper halves of the two cylindrically projected areas A and A are entirely folded into the inside of the trim cover assembly 2 and positioned therein. Subsequent thereto, the upper die 20 is completely mated with the lower die 10 to close the foaming die device 1, so that two upper half regions respective of the first and second rectilinear stay portions 5a and 5b are partly covered by the right- and left-side second stay receiving recessions 40c and 40c of the upper die 20, respectively, in an embraced manner. Hence, it is to be understood that a whole of the trim cover assembly 1 is securely placed within the cavity C, and the first substantially-rectilinear stay portion 5a is sandwiched between the right-side first and second stay receiving recessions 30c and 40c, whereas the second substantially-rectilinear stay portion 5b sandwiched between the left-side first and second stay receiving recessions 30c and 40c. It is therefore to be appreciated that, a worker has only to set the hollow trim cover assembly 1 in the cavity C of the foaming die device 1 and simply cause the two cylindrically projected areas A and A exposed exteriorly of the trim cover assembly to turn over at the first and second semi-cylindrical protrusions 30b and 40b relative to the two stay passage holes 2a and 2b, respectively, into the inside of the trim cover assembly 1. This eliminates the previously-described conventional preliminary steps requiring troublesome use of cylindrical sticks to press and turn over the cylindrically projected areas into the inside of trim cover assembly.

[0055] Thereafter, as shown in FIGS. 5 and 6, a liquid foaming agent is injected, via an injection nozzle 45 inserted in the lower die 10, into the inside of the trim cover assembly 2 and cured to form an increased mass of foam padding 3 filled in trim cove assembly 2. During this foaming process, both two cylindrically projected areas A and A, which project interiorly of the trim cover assembly 2, are forcibly brought by such increased mass of foam padding 3 to close contact about the first and second substantially-rectilinear stay portions 5a and 5b of the headrest stay 5, respectively. Thereby, all those two cylindrically projected areas A and A are positively retained against movement from the two substantially-rectilinear stay portions 5a and 5b, respectively.

[0056] At the completion of this foaming, the upper and lower dies 20 and 10 are rotated away from each other relative to the hinge 6 to open the foaming die device 1. With this opening, it is to be understood that the right-side first and second semi-cylindrical protrusions 30b and 40b are disengaged from each other, while being simultaneously withdrawn outwardly from the first stay passage hole 2a, whereas at the same time, the left-side first and second semi-cylindrical protrusions 30b and 40b are also disengaged from each other, while being simultaneously withdrawn outwardly from the second stay passage hole 2b. Thus, all the semi-cylindrical protrusions 30b and 40b are automatically removed from all the two stay passage holes 2a and 2b at one time, when opening the foaming die device 1. Consequently, a resulting headrest HR is obtained, in which both two cylindrically projected areas A and A created about the respective first and second stay insertion holes 2a and 2b are firmly retained in the foam padding 3 and prevented from being exposed exteriorly of the trim cover assembly 2 at peripheral regions of the first and second substantially-rectilinear stay portions 5a and 5b, respectively. Hence, the outer appearance of the headrest HR is improved aesthetically.

[0057] Additionally, in accordance with the present invention, it is to be appreciated that the following advantages and effects are attained: [0058] (i) Each of the left-side first and second semi-cylindrical protrusions 30b and 40b as well as each of the right-side first and second semi-cylindrical protrusions 30b and 40b is so formed to become smaller in thickness as it proceeds to the distal end thereof. This tapered configuration in effect permits two lower halves of the first and second stay passage holes 2a and 2b to smoothly slide on and along the right- and left-side first semi-cylindrical protrusions 30b and 30b in the longitudinal direction of the first and second substantially-rectilinear stay portions 5a and 5b, respectively, thereby being easily turned over along the curved surface F of that semi-cylindrical protrusion 30b relative to the first stay passage hole 2a and entered into the inside of the trim cover assembly 2, while on the other hand permitting two upper halves of the first and second stay passage holes 2a and 2b to smoothly slide on and along the right- and left-side second semi-cylindrical protrusions 40b and 40b in the longitudinal direction of the first and second substantially-rectilinear stay portions 5a and 5b, respectively, thereby being easily turned over along the curved surface F of that semi-cylindrical protrusion 40b relative to the second stay passage hole 2b and entered into the inside of the trim cover assembly 2. Thus, it is possible for a worker to easily cause complete insertion of all the first and second semi-cylindrical protrusions 30a and 30b into all the corresponding stay passage holes 2a and 2b in assured manner. [0059] (ii) The first and second stay receiving elements 30 and 40 themselves are provided independently of the lower and upper dies 10 and 20, respectively. When those two stay receiving elements 30 and 40 become worn out of use, it is easily possible to replace them all or either of them by new corresponding stay receiving element (s). Moreover, one or both of the two stay receiving elements 30 and 40 can be modified in terms of technical design and specifications, as required. [0060] (iii) Also, the first and second stay receiving elements 30 and 40 can be easily secured to and removed from the lower and upper dies 10 and 20, respectively, by use of the screws 1, which enables a worker to easily replace one or both of those two stay receiving elements 30 and 40 by a new corresponding stay receiving element(s)

[0061] FIGS. 7 and 8 illustrate a second alternative embodiment of the present invention, wherein another stay receiving element 50 is provided, which has a toothed semi-cylindrical protrusion 50a. This embodiment indicates that each of the foregoing first and second stay receiving elements 30 and 40 may be formed to have a toothed distal end. Namely, as far as the embodiment of FIGS. 7 and 8 is concerned, the stay receiving element 50 corresponds to the first stay receiving element 30, and therefore, the first stay receiving element 30 may be formed with a toothed semi-cylindrical protrusion identical to the toothed semi-cylindrical protrusion 50a of the stay receiving element 50. The same goes for the second stay receiving element 40. In other words, it is to be understood that a first toothed semi-cylindrical protrusion 30b and a second toothed semi-cylindrical protrusion 40b may be provided in the lower and upper dies 10 and 20, respectively. It is noted that all like designations given in the FIGS. 7 and 8 correspond to all like designations in FIGS. 1 to 6, and any further description on common parts and elements between this second embodiment and the foregoing first embodiment shown in FIGS. 1 to 6 is omitted for the sake of simplicity of description. According to the present second embodiment, the toothed mode provides a plurality of pointed distal ends in each of the first and second semi-cylindrical protrusions 30 and 40. Such pointed distal ends are effective in reducing a coefficient of friction between the bottom wall 2c of the trim cover assembly 2 and the first and second semi-cylindrical protrusions 30b and 40b. With this arrangement, it is to be appreciated that the right-side first and second semi-cylindrical protrusions 30b and 40b can be smoothly inserted in the first stay passage hole 2a in a less frictional contact with the bottom wall 2c of the trim cover assembly 2, and also, the left-side first and second semi-cylindrical protrusions 30a and 40a can be smoothly inserted in the second stay passage hole 2b in a less frictional contact with the bottom wall 2c.

[0062] Finally, it should be understood that the invention is not limited to the illustrated embodiment, but any modification, replacement and addition may be applied thereto, without departing from the scope of the appended claims.