PROCESS FOR PREPARING INTEGRALLY MOLDED SEATS

Abstract: An integrally molded seat to be used, for instance, for automobile seat, and a process for making the same are dis­ closed herein. The seat of the invention comprises a foamed body (29) and a covering material (11) enveloping the foamed body (29). The covering material (11) is secured only at its top portion (21) integrally with the top surface of the foamed body (29). The process of the invention involves setting the covering material (11) in a mold (10) such that only the top portion (21) thereof is placed in the mold (10) and subject to molding opera­ tions so that no excessive stretching forces are applied to the covering material (11). The mold (10) used in the invention has a novel construction in that it comprises a lower mold section (13) having relatively shallow or flat configurations defining only top surface configurations of the seat to be manufactured, and an upper mold section (12) having side walls a top wall which, respectively, define the side and bottom shapes of the seat.

Description: PROCESS FOR PREPARING INTEGRALLY MOLDED SEATS Technical Field The present invention relates to an integrally molded seat and a process for preparing the same, and more particularly to an integrally molded seat obtained by shaping a top surface or a central portion of a cover material integrally with a foamed material within a novel shaping and foaming mold. Background Art Automobile seats generally comprise back portions against which drivers or passengers lean their backs and sitting portions on which they sit. Such seats, particularly sitting portions thereof, are conventionally manufactured by various methods among which is included a process for molding foamed seat bodies integrally with covering.materials enveloping the bodies. Such integrally molding process in the prior art comprises a) placing the covering material in the lower half of a shaping and foaming mold, b) shaping the covering material into configurations corresponding to the inner surface of-the lower half of the mold by vacuuming through ports formed in the inner surface of the lower mold half and connected to a vacuum source, c) pouring foaming stock, for example, molten polyurethane stock, onto the shaped covering material in the lower half of the mold, d) closing upper and lower old halves together and causing the stock to foam by heat and psre thereby to totally combine together the foatned body and covering material enveloping the body The shaping and forming mold utilized in the prior art process is 1illustrated in Fig. 1, in which the mold comprises an upper half 1 of the piate-like shape and a lower half 2 '##v-; ng a #trapezoidal cross-sectional confi guration. The upper mold haif 1 is provided with an open¯ ing 3 for pouring polyurethane foaming stock and closable with an appropriate lid. The lower mold half 2 has an opening upper edge and suction ports at the bottom portion which corresponds in configurations to upper surface configurations of the seat to be formed. The lower mold half 2 is supported on a mounting base B. A covering material 4 is placed in the lower mold half 2 such that its central portion or top portion 7 is in touch with the bottom surface of the lower mold half 2 and its surrounding portions 5 which will form the four sides of a finished seat that has its lower edges 6 positioned adjacent to the upper edge of the mold 2. Then, the upper mold half 1 is closed against the lower mold half 2, and upon softening the covering material 4 by heating, vacuum is operated through suction ports in the mold bottom to cause the top or central portion 7 and the surrounding or side portion 5 of the covering material 4 to be shaped into configurations of the bottom surface and side wall surface of the lower mold half 2, respectively. Onto the covering material 4 thus shaped is poured foaming stock such as molten polyurethane for making a foamed body. Upon completion of foaming operation a seat is obtained in the form of the foamed body enveloped totally by and integrally combined with the covering material at its upper and four (4) side portions. The prior art processes, however, have many disadvantages which include inaccuracy in the shaping of the covering material due to great stretching needed for the covering material to be deeply drawn conforming to the configurations of the deep lower mold half. After removed from the mold, shaped covering material on the foamed body tends to shrink for overcoming excessive stretching forces thereby to spoil shape stability of the resultant seat. Moreover, in the prior art, the covering material should be a one-piece sheet without any seam or joint so as to endure deep stretching forces so that it is infeasible to use, in making four sides of the seat, material different in color or quality from the central portion in accordance with the purposes of designing. In addition, as seen in Fig. 1, the covering material 4 must have wide margins 4a to be effectively clamped by mold halves 1 and 2 and these margins will never be used as a part of the seat after removal from the mold. In order to avoid these disadvantages inherent in the prior art processes, the production steps must be taken separately for the foamed body, on one hand, and the covering material, on the other hand. For example, the molding is utilized only for making foamed body of polyurethane and sewing steps are utilized for making the covering material of the configuration capable of closely enveloping the foamed body, and assembling steps#are utilized to secure the covering material onto the foamed body by, for example, sewing or bonding techniques. Such separate production steps, however, also have many defects in that they are cumbersome and time-consuming because of complicated sewing processes of cover top and cover sides as well as assembling processes of the sewn cover and the foamed seat body and in that they are not perfect in combining together the cover and the foamed body so that the cover material may be moved from the foamed body and/or wrinkles may be formed in the cover material. Disclosure of the Invention Accordingly, it is an object of the present invention to provide an integrally molded seat which has an excellent stability in shape and dimension as the covering material is not subject to excessive stretching forces. It is another object of the present invention to provide a process for manufacturing an integrally molded seat of the features above-described in a simple and economical manner. It is yet another object of the present invention to provide ar integrally molded seat in which different color or dit-ferertH quality rbiOterials may be employed as to the central portion and side portions of the cover material notwithstanding relying upon the integrally molding process. It is a further object of the present invention to provide an integrally molded seat which does not require cumbersome and complicated sewing processses and assembling processes and in which the cover material will never be removed from the foamed body so as to effectively prevent wrinkles from being produced. It is a yet further object of the present invention to provide an integrally molded seat in which the cover material requires no clamping margins which leads to savings in cover material used. Briefly, the present invention provides an integrally molded seat, particularly a sitting portion thereof, which comprises a foamed seat body and a covering material enveloping the body. The foamed seat body has a top surface, a bottom surface and four sides connecting the top and bottom surfaces. The covering material comprises a cover top or central portion having four border edges which is to envelop and be secured integrally with the top surface of the foamed body and a cover side portion joined at its one longitudinal edge to the four border edges of the cover top or central'portion for enclosing four sides of the foamed body. The cover top or central portion of the cover material is'secured at its rear face integrally with the top surface of the foamed body and concurrently with foaming process of the seat body. The cover top may also be formed with any desired patterns or figures thereon during the course of the foaming process by using a mold having inner configurations complementary to the desired patterns. The cover side portion conceals the four sides of the foamed body by merely enveloping them and the other longitudinal edge or free edge of the cover side portion may be fixed to an appropriate support behind the bottom of the foamed body. Such integrally molded seat of the present inven tion is manufctured by using a mold of a novel construction. This novel mold comprises an upper mold half having a top wall and side walls for defining respectively the shapes of the bottom and four sides of the foamed body to be produced and having no bottom, and a lower mold half defining by its top surface the configurations of the top surface of the foamed body and forming the bottom for the upper mold half when two mold halves are closed against each other. Between the lower mold half and the side walls of the upper mold half is clamped the cover top or central portion of the cover material at or adjacent to its border edges. The top surface of the lower mold half may be provided with any desired patterns or figures for the foamed body top surface besides usual concave configurations on the top surface of the seat. The top surface of the lower mold half is also provided with suction ports communicating with a negative pressure source for shaping the cover top or central portion of the cover material into the configurations defined on the top surface of the lower mold half. The upper mold half has at its top wall an opening for supplying foaming stock such as molten polyurethane composition through the upper mold half onto the shaped cover material on the lower mold half. The upper mold half may be divided into two sections at the juncture between its top and side walls. The upper mold of this type permits easy release of the foamed product from the mold. The present invention also provides a process for manufacturing the integrally molded seat as defined above, which process comprises the steps of: a) setting the covering material in the mold such that only the cover top or central portion is contacted at its outer surface with the top surface of the lower mold half and the cover side portion surrounding the cover top remains outside the mold even after the mold halves are closed, b) clamping the cover material by the closed mold halves at the location adjacent to the border edges betwecrl the cover top and the cover side portion, c) shaping the cover top into the configura tions defined by the top surface of the lower mold half by means of vacuuming through the suction ports formed in the top surface of the lower mold half and, at the same time, supplying foaming stock such as molten polyurethane onto the shaped cover top in the closed mold halves for forming a foamed seat body secured only at its surface intended to be a top surface integral with the cover top, and d) after removing the foamed body together with the cover material from the mold, inverting the same and enveloping the four sides of the foamed body with the cover side remaining unsecured with the foamed body. Brief Description of the Drawings The present invention will be described in detail in connection with preferred embodiments thereof shown in the drawings in which: Fig. 1 represents schematically a sectional view of the shaping and foaming mold employed in the prior art process; Fig. 2 represents a sectional view of a novel shaping and foaming mold employed in accordance with the process of the present invention, showing a covering material placed onto a lower mold half against which an upper mold half is closed; Fig. 2a shows a modified form of a shaping and foaming mold constructed in accordance with the present invention; Fig. 3 represents a perspective view partly broken away of a covering material to be used for enveloping and being secured with a foamed scat body through the integral molding process of the present invention; ; Fig. 4 represents a sectional view of the mold of the present invention showing polyurethane foaming stock being poured into the closed mold and onto the shaped cover material shown in a phantom l.ir:e; Fig. 5 represents d sectional view of a foamed body which, at its top surface, is integrally secured with a top portion of the cover material, side potions of the cover material being illustrated in an inverted position by solid lines and in a returned position by phantom lines; Fig. 6 represents a sectional view of an integrally molded seat of the present invention mounted onto a frame structure; ; Fig. 7 represents a sectional view of the lower mold half over which the covering material of the present invention is set in a manner different from the previous examples; Fig. 8 shows a modified manner of the process of the present invention in which a covering material is set to an upper mold half; and Fig. 9 shows yet further manner in which a covering material is set to an upper mold half. Preferred Embodiment for Carrying Out the Invention Referring now to the drawings, particularly to Figs. 2 through 6, a preferred embodiment of the invention will be specifically described. A shaping and foaming mold having novel configurations of the present invention is shown in cross-section generally at 10 in Fig. 2 in which a cover material made in accordance with the invention is also shown generally at 11 schematically in a state in which it is set in a mold. Specifically, the mold 10 is divided into two halves, i.e., an upper half 12 and a lower half 13, which are closed against each other at a mating face 25 provided at a location corresponding to the border edge between the sides and the top of the seat to be produced. The upper mold half 12 has at its top wall an opening 14 for pouring polyurethane stock which is closable with a lid 15 and defines a cavity 16 which, as illustrated in Fig. 2, has a substantially truncated pyramidal contour which corresponds to the contour of the seat to be produced in an inverted state. Alternatively, the cavity 16 may be made a substantially rectangular solid where a #uhs-tantially rectangular solid seat is to be produced. The lower mold half 13 has a top surface 27 which will form a bottom of the cavity 16 when the upper mold half is closed thereagainst and a peripheral edge which will form the mating face 25 when two halves 12 and 13 are closed against each other. The lower half 13 has at its top surface 27 a plurality of suction ports 18 which communicates with a sealed chamber 17 which, in turn, communicates through a pipe or conduit 19 with a vacuum source or suction pump 20. As seen from the drawings, the top surface 27 of the lower mold half 13 is formed with concave configurations conforming to the convex configurations usually formed on the top surface of the seat. In addition, the top surface 27 may be provided with any patterns or figures 28, such as patterns similar to those made by quilting operation, which are desired to be produced on the top surface of the seat. Reference numeral 11 indicates a covering material of the present invention which, in Fig. 2, is turned inside out and envelops the top surface 27 of the lower half 13 with its cover top 21 and the side walls of the lower half 13 with its cover side 22. Although the cover side 22 may appear to be plural pieces in the drawings, it is in reality a continuous piece surrounding the side walls of the lower mold half 13. Referring to Fig. 3, the covering material 11 to be used for the seat having an inverted truncated pyramidal configuration is shown in a perspective vicw partly broken away. The covering material 11 is made up of the cover top 21 and the cover side 22 conjoined together at a joint 23 by means of sewing or welding techniques. It is a feature of the present invention that a non-one-piece material can be employed as the cover material in the process for integrally molding the foamed seat. In the illustrated embo dinent, the cover Ftaterial 11 is intended to be used for ' enveloping the seat of the inverted truncated pyramidal configuration so that its cover side 22 is a narrower downwards as shown in Fig. 3. In this case, it is preferable to form at least one cut out portion 24 in the cover side 22 for the purpose of making easier the placing of the cover material 11 onto the lower mold half 13 in the inverted state. Two adjacent edges forming the cut out portion 24 are preferably made such that they overlap one over the other when the cover material 11 envelops the foamed body with its cover side 22 as will be explained in more detail hereinafter. Of course, the covering material will be a rectangular solid or flat box type without bottom where the seat to be produced is of substantially rectangular solid form. The cover top 21 may be made of leather-like polyvinyl chloride sheets, polyvinyl chloride films or woven or non-woven fabrics. When fabrics are utilized as the cover top, linings such as polyvinyl chloride films and the like should preferably be applied to the rear surface of the fabrics or any treatment suitable to decrease air permeability of the fabrics should be conducted. The cover side 22 may be made of material the same as or different from that of the cover top 21. As mentioned, hereinbefore, the cover side 22 is advantageously made of different material in color and/or quality from that of the cover top 21 for designing purposes and/or economical reasons. In performing molding operations, the cover material 11 is placed onto the lower mold half 13 in the reversed state as shown in Fig. 2, with the outer surface of the cover top 21 in contact with the top surface 27 of the mold half 13 and with the cover side 22 turned inside out enveloping the side walls of the mold half 13. The inner or rear surface of the cover top 21 is facing to the mold cavity 16 for receiving foaming stock thereon as will be described later. After .setting the cover material 11 in the mold 10, heating may be conducted with respect to the cover top 21 which is to be positioned within the interior of the mold 10. This serves to easily shape the cover top 21 into the configurations of the top surface 27 of the lower mold half 13 by means of vacuum operation through the ports 18. Heating may be achieved by means of infrared heating means or blowing of hot air through the opening 14 of the upper mold half 12 when closed onto the lower mold half 13. Then, foaming stock 29' such as, for example, molten polyurethane composition, will be poured into the mold. Prior to this, with the upper and lower halves 12 and 13 closed against each other, suction is performed through the ports 18 of the lower half 13 by the suction pump 20 to evacuate the space between the cover top 21 and the mold top surface 27 so as to deform and shape the cover top 21 into the concave configurations with small projections 28 of the mold half 13 as shown in the phantom line in Fig. 4. Onto thus shaped cover top 21, molten polyurethane stock 29' is supplied through the opening 14 of the upper mold half 12 into the cavity 16 and allowed to foam in situ until it densely fills the cavity 16. Upon completion of foaming operation, foamed body 29 is taken out from the mold 10 with the cover top 21 integrally secured to the top surface of the foamed body through molding action. This foamed body 29 with the integral cover top 21 is shown in Fig. 5 in the returned state after removal from the mold in which the cover side 22 is schematically shown upwards in solid lines. Then, the cover side 22. will be turned and lcc-red as indicated by arrow marks to the phantom line positions in which it will cover the sides of the foamed seat body 29. In Big. 6, the foamed body 29 enveloped totally with the cover top 21 and the cover side 22 is shown which is mounted on an appropriate frame structure 30 of the seat and secured thereto by fixing the lower end 31 of the cover side 22 to the frame structure 30, thus producing the integrally molded sitting portion or the seat. Where the foamed body 29 is of inverted trczoidal section as illustrated in Figs. 5 and 6, the cut out portion 24 as described before and shown in Fig. 3 is extremely useful to easily conduct turning of the cover side 22 from the solid line position to the phantom line position. According to the present invention, any desired patterns such as those 21a similar to quilting patterns may readily be developed in the surface of the cover top 21 through the use of the lower mold half which is formed at its top surface with suitable configurations or figures corresponding to the patterns desired for the cover top, thus obviating the quilting operations conventionally performed individually to the top portion of the cover material for designing or decoration purposes and the sewing or bonding processes for attaching the cover material to the separately prepared foam body. Reverting to Fig. 2a, a variation of the shaping and foaming mold of the present invention will be described. The mold 10' shown in Fig. 2a comprises an upper section 42 having no opening similar to the opening 14 in the previous embodiment, a middle section 43 and a lower section 44 which corresponds to the lower mold half 13 in the previous embodiment. The upper section 42 and the middle section 43 are separable from and engageable with each other at an upper mating face 45. The middle section 43 and the lower section 44 have their mating face therebetween, i.e., a lower mating face at 46. The lower section 44 has the same configurations, patterns and parts, etc. as those of the mold half 13, which are indicated by the same reference numerals, such as sealed chamber 17, suction ports 18, top surface 27, projections 28, etc. The cover material 11 is placed onto the lower section 44 and shaped into the desired configurations in the same manner as in Figs. 2 and 4. In operation, the upper section 42 is opened and the foaming stock is poured into the cavity formed by the middle and lower sections 43 and 44. Then, the upper section 42 is re-closed at the mating face 45 to accoMplish foaming operation. Upon completion of foaming, the upper section 42 is again opened and removed from the middle section 43 to take out the resultant foamed body with the cover material secured at its top integrally therewith. The structure of the mold 10' of the Fig. 2a variation permits the foamed body to be easily released from the mold 10', particularly at its corner portions'adjacent to the upper mating face 45. The covering material 11 of the present invention may be set in the mold in various manners of which a few examples are illustrated in Figs. 7, 8 and 9. Fig. 7 illustrates an example in which the cover material 11 is placed on the lower mold half 13 with its joint 23 positioned on and at the mating face 25, compared to the previous examples as shown in Figs. 2 or 2a in which joint 23 is positioned outside the mating face 25. If the upper mold half 12 as shown in Fig. 2 is firmly closed on the mating face 25, setting of the cover material 11 shown in Fig. 7 is effective to obtain the desire product similar to that shown in Fig. 5 except that the position of the joint 23 is shifted slightly upwards. In this manner, the foamed body will be integrally secured with the cover top to a point closely adjacent to the joint 23. Figs. 8 and 9 illustrate examples in which the cover material 11 is set to the upper mold section instead of the lower section. Setting the cover material in these manners obviates the need to turn the side portion of the cover inside out or vice versa. In Fig. 8, the joint 23 of the cover material is positioned outside the mating face 25 of the upper mold section, whereas in Fig. 9 the joint 23 is positioned at the mating face 25 so as to be clamped by the closed mold halves. The setting manner in Fig. 9 provides the same advantage as that of Fig. 7. It will be appreciated from the foregoing des- cription that the present invention has attained many effects and advantages over the prior art processes. Since setting of the cover material in ihe mold can be done easily, rapidly and accurately in the process of the pre sent invention without the fear of producing wrinkles or slacks in the portion of the cover material that is to be subject to shaping and molding action, a mass production process for integrally molding foamed seats of highly stable product quality can be achieved which otherwise would be of poor productivity and stability due to the difficult setting of the cover material in the prior art. As only the cover top is subject to shaping action under lesser stretching forces in the present invention, stability in shape and dimension of the molded products is highly superior to those obtained in the prior art and various shapes and configurations as desired can be easily presented on integrally foamed seats. The top portion and the side portion of the cover material can be made of different materials from each other in color, quality and the like so that a variety of design or decorative effects can be obtained with ease. In the prior art integrally molding process using the vacuuming step, polyvinyl chloride (PVC) sheets or fabrics are used as the covering materials of the seats. In case of the PVC sheets, however, they tend to loose their grains formed on the surface due to excessive stretching forces applied through deep drawing of the sheets by vacuuming. Some countermeasures must be taken to prevent or decrease this loss of grain in order to maintain the appearance of the covering sheets similar to that of natural leathers. On the other hand, fabrics are so permeable to air that suction Operations are not necessarily effective to properly shape the fabrics into the deep configurations of the mold. Some countermeasures are required to be taken here again to reduce air permeability of the fabrics. In contrast, the present invention does not require any of the countermeasures which otherwise would lead to additional steps, labors and costs, because the cover materials are not subject to excessive deep stretching' forces in the pro cress of the present invention. While the invention has been described and illus trated in connection with the specific embodiments, it should not be construed that the present invention be limited thereto as the true scope and spirit of the invention is defined solely by the appended claims.

Claims: CLAIMS 1. An integrally molded seat comprising: a foamed seat body having a top surface, a bottom surface and side surfaces, and a covering material having a top portion and a side portion attached to said top portion at a longi tudinal edge thereof, said top or central portion being secured inte grally at its rear face with said top surface of said foamed seat body through foaming'process, said side portion being used to envelop said side surfaces of the foamed seat body and adapted to be fixed at its other longitudinal edge to a support frame behind said bottom surface. 2. The integrally molded seat.as claimed in claim 1 wherein said covering material is stretchable and moldable at least at its top portion. 3. The integrally molded seat as claimed in claim 2 wherein said covering material is made of polyvinyl chloride sheet at least at its top portion. 4. The integrally molded seat as claimed in claim 1 where in said covering material is made of a fabric having a lining of polyvinyl chloride film. 5. The integrally molded seat as claimed in claim 1 where in said top portion and said side portion are made of materials different in color from each other. 6. The integrally molded seat as claimed in claim 1 where in said top portion and said side portion are made of materials different in quality from each other. 7. The integrally molded seat as claimed in claim 1 where in a joint is formed between said top and side por tions of the covering material. 8. The integrally molded seat as claimed in claim 1 where in said foamed seat body is of foamed polyurethane. 9. The integrally molded seat as claimed in claim 1 where in said top portion of the covering material integral ly secured with said top surface of said foamed body is formed with any desired surface patterns. 10. The integrally molded seat as claimed in claim 1 where in said side portion of said covering material is pro vided with at least one cut out portion. 11. A process for molding a foamed seat integrally with a cover material therefor comprising the steps of: ¯ a) providing a shaping and foaming mold composed of an upper mold half and a lower mold half, said upper mold half having a top wall and side walls defining respectively a bottom surface and side surfaces of the foamed seat to be produced and having an opening for supplying foaming stock, said lower mold half having a top surface configured correspondingly to configura tions of a top surface of the seat and having suction ports formed therethrough, said two halves being closable at a mating face therebetween, b) preparing a covering material having a top or central portion and a side portion attached at a lon- gitudinal edge thereof to said top portion, c) placing said covering material in said mold such that only said top portion of the covering material is contacted with said top surface of said lower mold half, and said side portion of said covering material remains outside said mold, d) closing said upper and Lower mold halves relative to each other to clamp said covering material at said mating face, e) shaping said top portion of said covering mater ial into the configurations of said top surface of the lower mold by vacuuming through said suction ports, f) supplying foaming stock onto the shaped top por tion of said covering material placed in the closed mold halves to cause said stock-to foam thereby to secure said top portion of cover material at its rear face integrally with the top surface of the foamed seat, and g) enveloping the sides of said foamed seat with said side portion of said covering material. 12. The process as claimed in claim 11 wherein, prior to said vacuuming during shaping, heating is conducted of said top portion of the covering material. 13. The process as claimed in claim 11 wherein said top surface of said lower mold half is formed with surface patterns such as those similar to quilting patterns. 14. The process as claimed in claim 11 wherein said covering material is placed onto said lower mold half with its side portion turned inside out. 15. The process as claimed in claim 11 wherein said covering material is set to said upper mold half with out turning its side portion inside out. 16. The process as claimed in claim 11 wherein said covering material is formed with a joint between said top and side portions thereof. 17. The process as claimed in claim 11 wherein said covering material has at its side portion at least one cut out portion. 18. A covering material to be used for an integrally molded seat comprising: a cover top for enveloping and being secured integrally with a top surface of a foamed seat body to be produced, and a cover side attached through a joint formed at its one longitudinal edge to said cover top for en veloping four sides of the foamed seat body to be pro duced, said covering material being at least at its cover top stretchable and moldable under heat and pressure. 19. The covering material as claimed in claim 18 wherein said cover top and said cover side are of different materials from each other and only said cover top is subject to shaping and molding operations. 20. The covering material as claimed in claim 18 wherein said side portion is formed with at least one cut out portion.

Inventors: OGAWA, TARO
Applicants: NAMBA PRESS WORKS CO. LTD.
Application year: 1983
Main classification: A47C7
IPC codes: B29C39, B68G7, B29C44, B29B7, A47C7