METHOD OF PRODUCING MOLDING MEMBERS

Abstract: A novel method of producing molding members for automobiles, formed at least partly of a synthetic resin material is disclosed. According to the method of the invention, synthetic resin material is extrusion molded into a continuous body (25) with a substantially constant cross-section throughout the entire length thereof. A controlled amount of the material is removed from the predetermined location of the continuous body, synchronously with the extrusion molding of the material, such that the cross-section of the continuous body varies in the longitudinal direction of the body. The continuous body subjected to the controlled removal of the material is then cut into the predetermined length of the molding member.

Description: The present invention relates to a method of producing molding members, for instance for automobiles, formed at least partly of a synthetic resin material. An automobile employs various kinds of elongate molding members formed at least partly of a synthetic resin material, such as drip molding members, front and rear window molding members, etc. Of these, the drip molding member extends along the front pillar and the side edge of the roof panel of the vehicle body, while front and rear window molding members extend respectively along the periphery of the front and rear window plates, i.e. along the front and rear pillars and the front and rear edges of the roof panel. A variety of requirements are imposed on the molding members, mainly from design and/or functional viewpoint, and resulted in an increased demand in the automobile industry for the molding members whose cross-sectional shape varies in the longitudinal direction. More particularly, one proposal is directed to a window molding member having side portions with a first predetermined cross-sectional shape, an upper portion with a second predetermined cross-sectional shape, and corner portions arranged between the side and upper portions, where the cross-sectional shape changes gradually from the first to the second. Another proposal is directed to a drip molding member composed of a core element in the form of a metal strip which has been shaped into the desired cross-sectional shape, as well as upper and lower lip elements of synthetic resin material which are integral with the core element and molded such that the core element is partly exposed to, and visible from outside as a longitudinally extending ornamental portion with a metallic luster. The lower lip element is of a cross-sectional shape that is substantially constant throughout the entire length, while the upper lip element has a pillar portion with a relatively wide first cross-sectional shape, a roof portion with a relatively narrow second cross-sectional shape, and a corner portion between the pillar and roof portions, where the cross-sectional shape changes gradually from the first to the second. To produce elongate molding members whose cross-sectional shape varies in the longitudinal direction, it has been a conventional practice to use a process which includes preparation of the core element by shaping the raw metal strip into the desired cross-sectional shape with a roll forming machine, press machine, etc., placing each core element in the mold of an injection molding machine, and subsequently molding the synthetic resin material into the desired configuration. With such a process, however, since the entire core element of the elongate molding member has to be completely accommodated in the mold, the molding machine as a whole becomes very bulky and requires a substantial space in the factory. Moreover, the process involves relatively complex steps with which the molding members can be produced only one by one, and it is thus difficult to improve the productivity. Another possibility for the production of such molding members is to physically divide each molding member into first and second extruded portions with the respectively predetermined cross-sectional shapes, which are connected with each other either by an injection molding process or by using a separate connection piece. However, connection of the two portions by means of the injection molding accompanies formation of undesirable burrs along the junctions and resultant deterioration in the appearance, while use of the separate connection piece results in the increased number of the required components and assembly steps. GB-A-2126151 shows a process in which a molding member having a lip portion is cut in a predetermined pattern by engagement with a cutter movable laterally to the member. The preamble of claim 1 is based on this disclosure. EP 118397 shows a device for extruding a molding member with a lip portion. This lip is immediately following the extrusion step, selectively permanently deflected from its extruded shape. Therefore, it is a primary object of the present invention to provide a novel method of producing elongate molding members for automobiles, having a cross-sectional shape which is variable in the longitudinal direction, in a facilitated manner and with an improved productivity. According to the present invention, there is provided a method of producing a molding member for instance for a front or rear window for an automobile which includes, viewed in cross-section, a main body adapted to cover a gap formed between a window plate and an automobile body panel, a lip section projecting from said main body and adapted to cover the outer periphery of said window plate, the molding member being formed at least partly of a synthetic resin and the method including the steps of extruding the synthetic resin material into an elongate continuous body with a substantially constant cross-section throughout the length thereof; and removing from a predetermined location of said continuous body a controlled amount of the synthetic resin material, synchronously with the extrusion of the synthetic resin material, such that the cross-section of said continuous body varies in the longitudinal direction thereof, characterised in that said main body further comprises a ridge section projecting from the lip section for preventing flow of water across said ridge section, and in that said controlled amount of the synthetic resin material is removed from that portion of said continuous body which corresponds to said ridge section of said molding member, by deflecting the lip section of the main body along the part from which the controlled amount is to be removed such that the ridge section engages means by which the controlled amount is removed and in that the continuous body is subsequently cut into predetermined lengths. With the above-mentioned method of the present invention, the longitudinally variable cross-sectional shape of the molding member can be readily obtained essentially based on extrusion molding technology, simply by removing a controlled amount of the synthetic resin material from a predetermined location of the continuous body after it has been extruded, and by subsequently cutting the continuous body into a predetermined length of the molding member. According to the present invention, all the process steps can be carried out continuously, as contrasted with the conventional injection molding method, so that it is possible to produce the molding members with the desired, longitudinally variable cross-sectional shape, by means of a compact arrangement of the facility, and with a markedly improved productivity. Moreover, connection of separately extruded portions of a molding member, either by means of an injection molding process or by a connection piece, is not necessary, so that the present invention does not require the assembly of a plurality of components when producing a molding member, and preserves an excellent appearance of the product in an advantageous manner. Fig. 1 is a perspective view of an automobile with molding members which may be produced by the method in accordance with the present invention; Fig. 2 is a system diagram of the production line for carrying out the method of the present invention, which is adapted to produce various molding members; Fig. 3 is a sectional view of the side portion of the window molding member, which may be produced by the method in accordance with the present invention, and which has been secured to an automobile body; Fig. 4 is a sectional view of the upper portion of the window molding member shown in Fig. 3; Fig. 5 is a front view of the first cutting station adapted to produce the window molding member shown in Figs. 3 and 4; Fig. 6 is a sectional view taken substantially along the line B-B in Fig. 5; Fig. 7 is a front view similar to Fig. 5, but showing a different operational position of the forming roller; Fig. 8 is a schematic view showing the length of each portion of the window molding member; Fig. 9 is a diagram showing the relation between the displacement of the forming roller and the supplied length of the core element; Fig. 10 is a side view showing the modification to the cutting station shown in Figs. 5 and 6; The present invention will now be explained in further detail, by referring to some preferred embodiments shown in the attached drawings. There is shown in Fig. 1 an automobile designated as a whole by reference numeral 1, which is provided with various kinds of elongate molding members composed at least partly of a suitable synthetic resin material. These molding member include, among others, a front window molding member 2, a drip molding member 3, etc., and the present invention is applicable to produce these elongate molding members with an improved productivity, as will be fully explained hereinafter. The front window molding member 2 is arranged along the periphery of side or the windshield plate, and includes a pair of side or pillar portions 2a extending along the front pillars of the automobile 1, respectively, an upper or roof portion 2b extending along the front edge of the roof panel of the automobile 1, and a pair of corner portions 2c arranged between the pillar portions 2a and that roof portion 2b. Each pillar portion 2a has a predetermined first cross-sectional shape which is substantially constant throughout the entire length of that portion 2a. Similarly, the roof portion 2b has a predetermined second cross-sectional shape which is substantially constant throughout the entire length of that portion 2b, but which is different from that of the pillar portion 2a. Consequently, the shape of the pillar portion 2a gradually changes to that of the roof portion 2b in each corner portion 2c, or in its neighbourhood. On the other hand, the drip molding member 3 is arranged along the front pillar and the side edge of the roof panel of the automobile. The abovementioned molding members, 2,3 can be produced in the manner to be described hereinafter. Just for the sake of convenience, the following description will be made with reference to the production of the drip molding member 3. There is shown in Fig. 2 a system diagram of the production line for carrying out the method according to the present invention. The production line includes an uncoiler 11 from which a metal strip 12 is continuously supplied by a pair of pinch rollers 13. Another roller 14 serves to continuously supply a protective tape 15 which is separably adhered, by means of a pair of adhesion rollers 16, onto that portion of the metal strip 12 which eventually forms ornamental portions 5 of the molding member 3 with the desired metallic luster, and which has thus to be protected by the tape 15. The metal strip 12 applied with the protective tape 15 forms a composite body 17 which, subsequently, is subjected to surface degreasing and cleaning at a cleaning station 18 for carrying out a sanding or the like treatment, is coated with an adhesive material at a roll coating station 19, and is subjected to baking at the baking station 20. The composite body 17 is further passed through and cooled in a cooling tank 21, and is then shaped into a desired, longitudinally constant cross-section at a roll forming machine 22 to form a continuous core element 4 of the molding member 3. The core element 4 so obtained is supplied to a measuring station 23 which includes a rotary encoder or the like detector for measuring the supplied length of the core element 4, and then to an extrusion die 24 which is further supplied with a suitable synthetic resin material in its heated molten state. The molten synthetic resin material is co-extruded from the extrusion die 24 as a continuous extruded body 25 in which the upper and lower lip elements 6, 7 are made integral with the core element 4, whereby the extruded body 25 has a substantially constant cross-section which corresponds to that of the pillar portion 3a of the molding member 3. To produce molding members with a longitudinally variable cross-section, in accordance with the illustrated preferred embodiment of the present invention, the extruded body 25 as extruded from the extrusion die 24 is further subjected to the removal of a controlled amount of synthetic resin material from the predetermined location of the upper lip element 6. To this end, there is provided a controller 26 which is adapted to receive from the measuring station 23 a signal representing the supplied length of the core element 4, while a first cutting station 27 is arranged on the exit or discharge side of the die 24 and is adapted to be controlled by the controller 26 according to the supplied length of the core element 4. The extruded body 25 is subsequently passed through a cooling tank 28 where it is cooled, and is then advanced by a take-up device 29 and cut into the predetermined length of the product at a second cutting station 30 which, too, is controlled by the controller 26 according to the supplied length of the core element 4. Preferably, the removal of the synthetic resin material is carried out while the extruded body 25 is still hot and soft. The extruded body 25 subjected to the removal of the synthetic resin material at the first cutting station 27 is then supplied to the second cutting station 30 where it is cut into the predetermined length of the desired molding member 3 at predetermined positions of the extruded body 25 which correspond to the centers of the length 2L₁ and 2L₃, respectively. Furthermore, by repeating the above-mentioned operations, the molding members can be continuously produced one by one, in an efficient and reliable manner. An embodiment of the present invention, which is applied to the production of the window molding member, will now be explained with reference to Figs. 3 and 4. The molding member to be produced is designated as a whole by reference numeral 50, and is adapted to be arranged along the outer periphery of a front or rear window plate 51 which is formed of a transparent inorganic glass or transparent synthetic resin, such as polycarbonate resin, acrylic resin, or the like. The window plate 51 is secured to the automobile body panel 52 by means of an adhesive material 53, with a rubber dam member 54 arranged between the plate 51 and the body panel 52. The window plate 51 is further provided, on its rear surface, with an opaque printed layer 55 which extends along the periphery of the plate 51 so that the adhesive material 53 and the dam member 54 are not visible from outside, and which thus provides a highly refined appearance. The window molding member 50 includes a main body 56 which is formed of flexible and/or soft polyvinylchloride (PVC) resin, ionomer resin, ethylene-vinyl acetate copolymer (EVA) resin, transparent cellulose acetate butylate (CAB) resin, appropriate synthetic rubber material or other suitable thermoplastic and elastomeric synthetic resin material with a flexibility. The material forming the main body 56 is extruded about a metal strip forming a core element 57 which is thus embedded in the synthetic resin material of the main body 56. More particularly, as shown in Fig. 3 illustrating the cross-section of the molding member 50 at its side portion when the window plate 51 is a front window plate, the main body 56 of the window molding member 50 includes a leg section 58 extending into a gap 59 left between the window plate 51 and the automobile body panel 52. The main body 56 further includes a pair of lip sections 60, 61 formed on, and projecting from both sides of the leg section 58. The lip section 60 has a free end which bears against the outer surface of the automobile body panel 52, while the lip section 61 is formed with a projection 62 in the form of a ridge near the free end thereof, which bears against the outer surface of the window plate 51. The projection 62 cooperates with the free end of the lip section 61 and the window plate 51 to define a channel 63 which serves to prevent side flow of the water or rain drops 64 across the front pillar of the automobile, from the front window plate toward the side window, and effectively preserves the driver's and/or navigator's sight through the side window, during the driving of the automobile in rainy climate condition. In other words, the channel 63 guides the flow of water or rain drops 64 along the side edge of the front window plate 51. The channel 63 thus extends along the front pillar of the automobile, but is not required along the junction between the upper edge of the front window plate and the roof panel of the automobile; rather, provision of such a channel along the upper edge of the front window plate is undesirable since the channel prevents realization of the so-called flush outer surface of the automobile. Hence, as particularly shown in Fig. 4 illustrating the cross-section of the upper portion of the molding member 50, the lip section 61 of the main body 56 in its upper portion is not provided with the projection 62 with a sufficient length to define the channel 63. Furthermore, the lip section 61 assumes an angular position with reference to the leg section 58, which is different from that shown in Fig. 3, and is in direct contact with the surface of the window plate 51 as shown in Fig. 4. This means that the window molding member 50 shown in Figs. 3 and 4 has a cross-section which varies in the longitudinal direction. The window molding member 50 shown in Figs. 3 and 4 can be produced by the method according to the present invention, with a production line which is substantially the same as that shown in Fig. 2. According to the present embodiment, as shown in Figs. 5 to 7, the first cutting station 27 includes a stationary cutter member 65 which assumes a fixed position with reference to the extrusion die 24, a forming roller 66 supported by a movable frame 67 and adapted to be brought into contact with the lip section 61 of the extruded body 25 forming the molding member 50, thereby to deform the lip section 61 while it is still hot and soft. A screw threaded rod 68 connects the frame 67 with a reversible servomotor 69 which, in turn, is connected to a controller, like the controller 26 as shown in Fig. 2. Thus, the servomotor 69 is adapted to displace the forming roller 66 in the direction M' or N' as shown by double arrow in Figs. 5 and 6, in accordance with the length of the core element 57 supplied to the extrusion die 24. Assuming that, as shown in Fig. 8, the window molding member 50 has a pair of side portions 50a, 50b of the length L₁, a pair of corner portions 50c, 50d of the length L₂ and an upper portion 50e of the length L₃, the relation between the displacement of the forming roller 66 in the directions M' and N' and the supplied length of the core element 57 is as shown in Fig. 9. More particularly, during the period in which the die 24 discharges that portion of the extruded body 25 which corresponds to the side portions 50a, 50b of the molding member 50 with the length L₁, the forming roller 66 assumes its uppermost position and is out of contact with the surface of the lip section 61, while the cutter member 65 extends slightly into the projection 62 of the lip section 61 so that a controlled small amount of material is removed from the projection 62, as shown in Fig. 8. As the detector of the measuring station detects the completion of the supply of the length L₁ of the core element 57, or the beginning point of the corner portion 50c of the length L₂, the servomotor 69 is actuated in the normal direction, displacing the forming roller 66 in the direction N'. During this movement, the forming roller 66 comes into contact with the lip section 61 to deflect this section counterclockwisely with reference to the leg section 58, from an initial angular position shown in Fig. 7 to a deflected angular position shown in Fig. 5. Such a deflection of the lip section 61 causes the projection 62 to be lowered, as seen in Figs. 5 to 7, whereas the cutter member 65 assumes a fixed position with reference to the extrusion die 24, so that the projection 62 is subjected to the removal of the material with a gradually increasing depth. When the detector at the measuring station detects the completion of the supply of the length L₂ of the core element 57, or the beginning of the upper portion 50e of the molding member 50 with the length L₃, the servomotor 69 is stopped so that the forming roller 66 is maintained in its lowermost position. The resultant maximum deflection of the lip section 61 corresponds to the removal of the material from the projection 62 with the maximum depth. The forming roller 66 is maintained in this position until the detector of the measuring station detects completion of the supply of the length L₃ of the core element 57. The servomotor 69 is then actuated in the reverse direction to displace the forming roller 66 toward the uppermost position. The lip section 61 begins to restore into the initial angular position shown in Fig. 8, and the projection 62 thus moves upwardly with reference to the cutter member 65, so that the cutter member 65 removes material from the projection 62 with a gradually decreasing depth. The servomotor 69 is stopped as the detector of the measuring station detects completion of the length L₂ of the core element 57, and the forming roller 66 is maintained in its uppermost position shown in Fig. 7, for a new cycle of operation, until twice the length L₁ of the core element 57 is supplied to the extrusion die 24. The extruded body 25 is then cooled and solidified, and is further supplied to the second cutting station, like the station 30 shown in Fig. 2, where it is cut into the predetermined length of the window molding member 50 at a point X shown in Fig. 9, which is at the center of the two side portions. A modification to the above-mentioned embodiment is shown in Fig. 10, in which the cutter member 70 is arranged on or adjacent to the extrusion die 24 and is movable in the directions P' and Q', synchronously with the movement of the forming roller 66 in the directions M' and N'. The depth with which material is removed from the projection 62 is varied by the movement of the cutter member 70, while the forming roller 66 serves to deform the lip section 61 while it is still hot and soft. The window molding member 50 shown in Figs. 3 and 4 can be produced in a continuous manner as described above. To arrange the molding member in place, first of all, a strip-like retainer member 71 with a plurality of retaining fins is adhered to the side and upper webs 52a of the automobile body panel 52. The rubber dam 53 is preliminary secured onto the periphery of the rear surface of the window plate 51 which is then applied with adhesive material 53. The window plate 51 is then temporarily supported on the flange 52b of the body panel 52, and the leg section 58 of the molding member 50 is inserted, before the adhesive material 53 hardens, into the gap 59 between the body panel 52 and the window plate 51, engaging fins 58a and 58b of the leg section 58 with the retaining fins of the retainer member 71 and the rear edge of the window plate 51, respectively. From the foregoing description, it will be appreciated that the present invention provides a novel method of producing elongate molding members for automobiles, whereby the longitudinally variable cross-sectional shape of the molding member can be readily obtained essentially based on extrusion molding technology, simply by removing a controlled amount of the synthetic resin material from a predetermined location of the continuous body after it has been extruded, and by subsequently cutting the continuous body into a predetermined length of the molding member. The present invention is advantageous in that all the process steps can be carried out continuously, as contrasted with the conventional injection molding method, so that it is possible to produce the molding member with the desired, longitudinally variable cross-sectional shape, by means of a compact arrangement of the facility, and with a markedly improved productivity.

Claims: A method of producing a molding member (2,3,50) for instance for a front or rear window for an automobile (1), which includes, viewed in cross-section, a main body (50) adapted to cover a gap formed between a window plate (51) and an automobile body panel (52), a lip section (61) projecting from said main body (50) and adapted to cover the outer periphery of said window plate (51), the molding member being formed at least partly of a synthetic resin and the method including the steps of extruding the synthetic resin material into an elongate continuous body (25) with a substantially constant cross-section throughout the length thereof; and removing from a predetermined location of said continuous body (25) a controlled amount of the synthetic resin material, synchronously with the extrusion of the synthetic resin material, such that the cross-section of said continuous body (25) varies in the longitudinal direction thereof, characterised in that said main body (50) further comprises a ridge section (62) projecting from the lip section (61) for preventing flow of water across said ridge section (62), and in that said controlled amount of the synthetic resin material is removed from that portion of said continuous body (25) which corresponds to said ridge section (62) of said molding member, by deflecting the lip section (61) of the main body (50) along the part from which the controlled amount is to be removed such that the ridge section (62) engages means (65) by which the controlled amount is removed and in that the continuous body (25) is subsequently cut into predetermined lengths. A method as claimed in claim 1, wherein said controlled amount of the synthetic resin material is removed from the continuous body (25) after the continuous body (25) has been extruded, while it is still hot and soft. The method as claimed in claim 1 or 2, wherein said continuous body (25) is formed by continuously supplying a core element (4,58) to an extrusion die (24) through which said synthetic resin material is extruded with said core element (4,58), and wherein said controlled amount of the synthetic resin material is removed from the continuous body (25) in accordance with the supplied length of said core element. The method as claimed in claim 1, 2 or 3, wherein said molding member is a front window molding member (2) for an automobile (1), and has an upper portion (2b) adapted to extend along the junction between an upper edge of said window plate and a roof panel of the automobile (1), and wherein said controlled amount of the synthetic resin material is removed from that portion of said continuous body (25) which forms said upper portion (2b) of said molding member. The method as claimed in claim 1, 2 or 3, wherein said molding member is a rear window molding member for an automobile, and has side portions to extend along the junction between side edges of said window plate and rear pillars of the automobile, and wherein said controlled amount of the synthetic resin material is removed from those portions of said continuous body which form the side portions of said molding member.

Inventors: IGARASHI, NOBUO HASHIMOTO FORMING, KONNO, SADAO HASHIMOTO FORMING, NAKAJIMA, HIROYUKI HASHIMOTO FORMING, TAMURA, TATSUYA HASHIMOTO FORMING
Applicants: HASHIMOTO FORMING INDUSTRY CO  LTD
Application year: 1988
Main classification: B29C47
IPC codes: B60R13, B29C47, B60J10, B60J1, B29C69, B29C67, B26D3, B29D99