METHOD OF MANUFACTURING DOOR TRIM OF MOTOR VEHICLE

Abstract: A method of manufacturing a door trim for a motor vehicle having a decorative member attached thereto, wherein a non-preformed decorative member is contact-bonded and fixed by use of a mold for contact bonding to the main body of a door trim according to its complicately curved surface, excessive portions of the decorative member are cut away by a fusing blade attached to a bottom tool for contact bonding, and the decorative member is subjected to a peripheral/end edge treatment by a press-in bar. Consequently, preforming for the decorative member can be dispensed with and there is no need of allowing for the positioning accuracy of the decorative member preset in a complicated three-dimensional shape, unlike the conventional method in which molded products are contact-bonded to each other by positioning, so that such advantages can be offered that the work efficiency can be improved greatly, such faulty appearance that the decorative member sticks out of predetermined portions can be reliably avoided, thereby remarkably improving the productivity, workability and the appearance of the product.

Description: TECHNICAL FIELD The present invention relates to a method for fabricating automotive door trims carrying ornamental members, and in particular to a method for fabricating automotive door trims carrying ornamental members which can simplify the process of mounting the ornamental members and improve the aesthetic appearance of the door trims. BACKGROUND OF THE INVENTION In recent years, to the end of improving the comfort quality of the interior of automobiles, measures have been take to improve the quality of the material for automotive door trims and to mount cloth, carpet and other ornamental materials on appropriate parts of the door trims. The conventional method of mounting such an ornamental member on a door trim consisted of molding the ornamental member into a desired shape, for instance, by a vacuum molding, trimming the peripheral part into a desired shape, and mounting the ornamental member on the door trim with a bonding die set. At such a time, the peripheral edge of the ornamental member is fitted into a peripheral groove formed in the door trim for the purpose of improving the appearance of the peripheral edge of the ornamental member. The ornamental member typically consists of an ornamental sheet made of such material as cloth or carpet which is backed by a backing member made of such material as polyvinylchloride in order to maintain the curved shape thereof. Therefore, it is known that a substantial increase in cost is incurred by the conventional method of mounting an ornamental member which involves a large number of steps such as the step of molding the ornamental member, the trimming step, the step of positioning the ornamental member, the step of integrally joining the door trim main body and the ornamental member, and the step of processing the peripheral edge of the ornamental member. Further, in order to impart the capability to retain its shape to the ornamental member, a backing material is required, and this not only causes an increase in the material cost but also creates the need to position the pre-formed ornamental member exactly in the bonding die set. In particular, when the ornamental part of the ornamental member is provided with a complicated three-dimensional shape, positioning the ornamental member in the bonding die set is extremely cumbersome, and this causes a significant reduction in the production efficiency. When there is any positional error in positioning the ornamental member in the bonding die set, it becomes impossible to accurately push the peripheral edge of the ornamental member into a peripheral groove of the door trim main body, and it causes the known problem of impairing the external appearance of the door trim because a part of the peripheral edge of the ornamental member is left exposed. FR-A-2,429,667 discloses a method for fabricating a door panel consisting of a substrate and a coating layer. DE-A-3,808,851 discloses a method of laminating a vehicle panel section using a combined pressure bar/knife to force and to cut a sheet in a groove. A primary object of the present invention is to provide a method for fabricating automotive door trims which can eliminate the need for the preliminary forming step for the ornamental member that is to be mounted on the door trim main body so as to simplify the fabrication process. Another object of the present invention is to provide a method for fabricating automotive door trims which allows the ornamental member to closely follow the profile of the door trim main body even when the part where the ornamental member is to be mounted is given with a complicated three-dimensional shape, and eliminate the need for accurate positioning the ornamental member so that the mounting of the ornamental member can be achieved in a short time. Yet another object of the present invention is to provide a method for fabricating automotive door trims which can maintain the satisfactory appearance of the door trim by allowing the peripheral edge of the ornamental member to be accurately forced into the peripheral groove of the door trim member. The invention provides a method for fabricating an automotive door trim in accordance with Claim 1. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of the present invention as well as the advantages thereof will become apparent from the following description of the present invention with reference to the appended drawings, in which: Figure 1 is a front view of an automotive door trim which is fabricated according to the method of the present invention; Figure 2 is a sectional view taken along line II-II of Figure 1; Figure 3 is a sectional view showing the structure of the bonding die which is used for carrying out the method of the present invention; Figures 4 through 7 show different steps of fabricating the door trim shown in Figure 1 by using the bonding die device illustrated in Figure 3; Figure 4 is a sectional view showing the step of placing the door trim main body and the ornamental member in the bonding die device; Figure 5 is a sectional view showing the step of pressure bonding the ornamental member to the door trim main body by engaging the bonding dies; Figure 6 is a sectional view of an essential part showing the step of cutting away extraneous parts of the ornamental member with a thermal cutting blade following the pressure bonding of the ornamental member on the door trim main body; Figure 7 is a sectional view of an essential part showing the step of forcing the peripheral edge of the ornamental member into the peripheral groove of the door trim main body following the step of cutting away the extraneous parts of the ornamental member; Figure 8 is a perspective view of a protector which may be optionally used in the step of cutting the ornamental member according to the present invention; Figure 9 is a sectional view of the overall structure of the bonding die device when the protector illustrated in Figure 8 is placed in a prescribed position; Figure 10 is a sectional view of an essential part showing the step of cutting extraneous parts of the ornamental member using the protector illustrated in Figure 8; Figure 11 is a perspective view of another embodiment of the protector; and Figure 12 is a sectional view of an essential part showing the step of cutting extraneous parts of the ornamental member using the protector illustrated in Figure 11. DESCRIPTION OF THE PREFERRED EMBODIMENTS To the end of achieving the above mentioned objects, the method for fabricating an automotive door trim of the present invention is characterized by the forming step consisting of forming a core member into a desired shape, forming a door trim main body by integrally bonding a surface skin member on a surface of the core member, and forming a peripheral groove along a peripheral edge of an area over which the ornamental member is to be mounted; and the integral assembly step consisting of applying a bonding agent on the area of the door trim main body on which the ornamental member is to be placed, placing this door trim main body on a surface of a bonding upper die, placing the ornamental member on a surface of a bonding lower die having a die surface adapted to a surface contour of the area of the door trim member over which the ornamental member is to be mounted, bonding the door trim main body and the ornamental member together by engaging the bonding upper and lower dies lifting a vertically moveable thermal cutting blade along an outer periphery of the bonding lower die until a peripheral edge of the ornamental member is cut by heat into a desired profile, lifting a pressure bar disposed along an inner circumference of the thermal cutting blade so that the peripheral edge of the ornamental member may be forced into the peripheral groove of the door trim member by the pressure bar. Before describing the method of the present invention, the structure of the automotive door trim which is to be fabricated by the method of the present invention is described in the following with reference to Figures 1 and 2. In Figures 1 and 2, the automotive door trim 10 essentially consists of a door trim main body 11, and an ornamental member 12 which may, for instance, consist of fabric mounted on a suitable part of the door trim main body 11. More specifically, the door trim main body 11 consists of a core member 13 made of wood fiber board or the like thermally press formed into a desired shape, and a surface skin member 14 integrally attached to the surface of the core member 13, for instance, by vacuum forming, and the surface skin member 14 is formed by laminating a foam layer 15 consisting of polypropylene, polyethylene or the like on the reverse surface of a surface skin sheet make of PVC sheet mixed with ABS, or the like. The door trim main body 11 is provided with a peripheral groove 17 around the periphery of the ornamental member 12, and this peripheral groove 17 is formed at the same time as the press forming of the core member 13. The ornamental member 12 may be appropriately selected from such fabric as velvet, jersey, tricot and moquette, and may be optionally laminated with a pad material on its reverse surface for the purpose of imparting a cushioning property thereto. Further, the peripheral edge 12a of the ornamental member 12 is forced into the peripheral groove 17 formed in the door trim main body 11 as an edge process for producing a favorable external appearance. The core member 13 may also be made of thermo-plastic composite resin plate or the like, and, in this case, the core member 13 having a desired shape can be obtained by cold press forming a sheet material which is softened by a preliminary heating step. Now the process of fabricating the automotive door trim 10 is now described in the following. First of all, with respect to this door trim main body 11, the core member 13 is formed into a desired shape by cold press forming, and the surface skin member 14 is integrally bonded on the surface of the core member 13 by vacuum forming or the like. Figure 3 shows the structure of the bonding die device employed for the step of integrally joining the door trim main body 11 and the ornamental member 12, and this device comprises a bonding upper die 20 on which the door trim main body 11 is to be placed, a bonding lower die 21 on which the ornamental member is to be placed, a vertically moveable thermal cutting blade 22 arranged around the outer periphery of the bonding lower die 21, and a vertically moveable pressure bar 23 placed along the inner periphery of the thermal cutting blade 22. Below the thermal cutting blade 22 and the pressure bar 23 are provided lifting devices 24 and 25, respectively, which may, for instance, consist of hydraulic cylinders so that the thermal cutting blade 22 and the pressure bar 23 may be independently moved vertically. The bonding lower die 21 is also vertically moveable by a lifting device not shown in the drawing so that the bonding lower die 21 may move toward and away from the bonding upper die 20. Now the process of integrally joining the door trim main body 11 with the ornamental member 12 by mounting the latter on the former is described in the following with reference to Figures 4 through 7. Now, as illustrated in Figure 4, the door trim main body 11 is placed on the bonding upper die 20 with face down, and the ornamental member 12 is placed on the bonding lower die 21. The peripheral part of the ornamental member 12 is retained by a clamp device 26. During the step of positioning the door trim main body 11 and the ornamental member 12, the thermal cutting blade 22 and the pressure bar 23 are placed at their lowermost positions. Then, upon completion of this positioning step, the bonding lower die 21 is lifted until the bonding upper and lower dies 20 and 21 are engaged as illustrated in Figure 5. Since a bonding agent is applied to the part of the door trim main body 11 corresponding to the ornamental member 12 in advance, the ornamental member 12 is securely bonded to the door trim main body 11 closely following its complicated profile when the bonding upper and lower dies 20 and 21 illustrated in Figure 5 are engaged. When the bonding upper and lower dies 20 and 21 are engaged, the first lifting device 24 is activated and the thermal cutting blade 22 is lifted until it thermally cuts off extraneous parts of the ornamental member 12 as illustrated in Figure 6. As can be seen from Figure 6, the prescribed position of the thermal cutting blade 22 is defined slightly outwardly of the peripheral groove 17 formed in the door trim main body 11. Upon completion of the cutting step by the thermal cutting blade 22, the first lifting device 24 is activated and the thermal cutting blade 22 is lowered. In synchronization with it, the second lifting device 25 is activated, and the pressure bar 23 is started to be lifted so as to force the peripheral edge 12a of the ornamental member 12 into the peripheral groove 17. Since the thermal cutting blade 22 is placed a certain predetermined distance away from the outer periphery of the bonding lower die 21, the dimension of the peripheral edge 12a of the ornamental member 12 that is forced into the peripheral groove 17 is always constant. Thus, according to the present invention, since the extraneous parts of the ornamental member 12 is thermally cut off by the thermal cutting blade 22 when press bonding the door trim main body 11 and the ornamental member 12 with the bonding upper and lower dies 20 and 21, the conventionally necessary steps of molding the ornamental member 12 and trimming the ornamental member 12 can be eliminated, and a substantial reduction in cost can be achieved through the simplification of the fabrication process. Further, according to the present invention, since the ornamental member 12 is cut into a desired shape by the thermal cutting blade 22 disposed around the outer periphery of the bonding lower die 21, and the accuracy of positioning is not so important as in the case of the conventional process in which the molded members were required to be positioned and bonded together, the production efficiency can be improved even when the ornamental part of the door trim main body 11 is given with a complicated three-dimensional shape. Additionally, according to the present invention, the ornamental member 12 is not required to be capable of retaining its shape because the thermal cutting blade 22 cuts off the extraneous parts of the ornamental member 12 after the door trim member 11 and the ornamental member 12 are bonded by the bonding upper and lower dies 20 and 21 with the ornamental member 12 closely following the three-dimensional contour of the door trim member 11, and the need for the conventional backing member is eliminated, so that a substantial reduction in the manufacturing cost can be achieved through savings in the material cost. According to the present invention, since the ornamental member 12 may be cut to an accurate profile with the thermal cutting blade 22, there is no need to consider the positioning accuracy, and the peripheral edge 12a of the ornamental member 12 may be forced into and secured in the peripheral groove 17 of the door trim main body 11 by a fixed width so that the peripheral edge 12 of the ornamental member 12 is processed in a neat fashion, and the overall external appearance of the finished product is accordingly improved. Now an alternate embodiment of the present invention is described in the following. Figure 8 is an external appearance view of a protector 27 that is employed in the step of cutting the extraneous parts of the ornamental member 12, and this protector 27 consists of a frame made of metallic plate placed along the outer periphery of the peripheral groove 17 of the door trim main body 11 as illustrated in Figure 8. This protector 27 is placed and secured along the outer periphery of the peripheral groove 17 of the door trim main body 11 when it is placed on the surface of the bonding upper die 20 as illustrated in Figure 9. Therefore, during the step of cutting the ornamental member 12 with the thermal cutting blade 22, the cutting edge 22a of the thermal cutting blade 22 touches the ornamental member 12 and contacts the protector 27 after melting and cutting the ornamental member 12 so that protector 27 may protect the surface skin member 14 of the door trim main body 11 with the result that the risk of cutting or otherwise damaging the surface skin member 14 or leaving shiny spots on the surface skin member 14 can be eliminated. Also, since the protector 27 can prevent the heat and the excessive pressure of the thermal cutting blade 22 from adversely affecting the ornamental member 12, the surface skin member 14 is favorably protected, and the protector 27 eliminates the need for a high level of accuracy in the pressure of the bonding lower die 21 and the dimensions of the thermal cutting blade 12. Since the trimming of the ornamental member 12 can be carried out very quickly with heat and pressure by pressing the cutting edge 22a of the thermal cutting blade 22 which is guided by the protector 27, the fabrication time is reduced without adversely affecting the surface of the ornamental member 12 in any way, and there is provided a highly practical fabrication method. A modified embodiment of the protector 27 employed in the present invention is now described with reference to Figures 11 and 12. This protector 27 includes a spacer 28 which is placed along the inner periphery of the protector 27 as illustrated in the drawings, and, according to this particular embodiment, the spacer 28 made of such heat resistant material as mica is secured to the protector 27 made of metal by using a bonding agent. By changing the thickness of the spacer 28 (indicated by "l" in the drawing) as illustrated in Figure 12, the width (indicated by "l₁" in the drawing) of the peripheral edge 12a of the ornamental member 12 that is to be forced into the peripheral groove 17 can be adjusted. Thus, this embodiment offers a high level of freedom in design since the protector 27 allows the configuration of the peripheral groove 17 of the door trim main body 11 and the depth of the peripheral groove 17 to be freely determined.

Claims: A method for fabricating an automotive door trim by mounting an ornamental member on a predetermined surface area of a door trim main body, comprising the steps of: forming a core member (13) into a desired shape; forming a door trim main body (11) by integrally bonding a surface skin member (14) onto a surface of said core member (13); forming a peripheral groove (17) along a peripheral edge of an area over which an ornamental member (12) is to be mounted; and applying a bonding agent on said area on which said ornamental member (12) is to be mounted, characterized by further comprising the steps of: placing said door trim main body (11) on a surface of a first bonding die (20), placing said ornamental member (12) on a surface of a second bonding die (21) having a die surface contour complementary to a surface contour of the area of said door trim member (11) over which said ornamental member (12) is to be mounted; bonding said door trim main body (11) and said ornamental member (12) together by engaging said first and second bonding dies (20) and (21); moving a thermal cutting blade (22) provided along an outer periphery of said second bonding die (21) until a peripheral edge of said ornamental member (12) is cut by heat into a desired profile; and moving a pressure bar (23) disposed along an inner circumference of said thermal cutting blade (22) to contact press said peripheral edge of said ornamental member (12) into said peripheral groove (17) of said door trim member (11). A method for fabricating an automotive door trim according to claim 1, characterized in that said ornamental member (12) consists of a fabric. A method for fabricating an automotive door trim according to claim 1 or 2, characterized in that said core member (13) of said door trim main body (11) consists of wood fiber board which is heated and pressed into a desired shape. A method for fabricating an automotive door trim according to claim 1, 2, or 3, characterized in that said surface skin member (14) of the door trim main body (11) consists of a surface skin sheet (16) laminated with a foam layer (15) over its reverse surface. A method for fabricating an automotive door trim according to claim 1, 2, 3 or 4, characterized in that a protector (27) is placed between said thermal cutting blade (22) and said door trim main body (11) when said ornamental member (12) is being thermally cut by said thermal cutting blade (22) so that said surface skin member (14) of said door trim main body (11) may be protected by said protector (27). A method for fabricating an automotive door trim according to claim 5, characterized in that a spacer (28) is placed along an inner peripheral surface of said protector (27) so that the width of said peripheral edge of the ornamental member (12) that is to be forced into said peripheral groove (17) of said door trim main body (11) is determined by the thickness of said spacer (28).

Inventors: NOGUTI KAORU, YAMAGUCHI YOUICHI, YANAGIYA TAKAO, NOGUTI, KAORU, YAMAGUCHI, YOUICHI, YANAGIYA, TAKAO, NOGUTI, KAORU, SAMUKAWA FACTORIES, YAMAGUCHI, YOUICHI, SAMUKAWA FACTORIES, YANAGIYA, TAKAO, SAMUKAWA FACTORIES
Applicants: KASAI KOGYO KK, KASAI KOGYO CO., LTD.
Application year: 1990
Main classification: B29D31
IPC codes: B60J5, B29C65, B29C63, B29C69, B29D99