A combination extrusion head assembly for producing weather strip

Abstract: A first uncured pasty material is led into a shaping passage (43a,45a,47a,53a) to produce an uncured shaped molded strap. A second uncured pasty material is applied through an inlet passage (47c) onto a given portion of the uncured shaped molded strap while it is moving through the shaping passage, thereby to produce a layered uncured shaped molded strap, which is then cured.

Description: The present invention relates in general to a weather strip which is mounted to an automotive door window frame, an automotive door opening or the like, and more particularly, the present invention relates to a combination extrusion head assembly for producing such weather strips. In order to clarify the task of the present invention, a known weather strip used in the above-mentioned automotive field will be described with reference to Fig. 7 of the accompanying drawings. The known weather strip shown in the drawing is a glass runner 10 which is mounted to the inside wall of an automotive window frame 100. The glass runner 10 is generally constructed of elastic material, such as natural rubber, synthetic rubber, thermosetting resin or the like. The glass runner 10 comprises a base portion 1 attached to the window frame 10, side wall portions 3 and 5 raised from both sides of the base portion 1, and lip portions 3a and 5a extending inwardly downward and obliquely from respective tops of the side wall portions 3 and 5 toward the base portion 1. The base portion, the side wall portions 3 and 5 and the lips 3a and 5a constitute a glass runner proper 10'. Designated by numeral 7 is a window glass which is slidably contactable with the lip portions 3a and 5a during its opening and closing movement. The inside wall of the base portion 1 and the outside walls of the lip portions 3a and 5a are each equipped with a low friction layer 11 for improving the sliding ability of the window glass 7 relative to the glass runner 10. Due to provision of such friction layers 11, the wear resistance of the glass runner 10 against the window glass 7 is also increased. The friction layer 11 is usually constructed of thermoplastic resin, such as polyethylene resin (PE), polypropylene resin (PP) or the like. In order to produce weather strips 10 of the type described hereinabove, many methods have been proposed and put into practical use. Some of them are shown in Japanese Patent First Provisional Publications Nos. 2-269039, 2-269040, 2-269041, 3-24947 and 2-212118. In fact, these publications disclose various methods for providing the glass runner proper 10' with the friction layers 11. In these conventional methods, the glass runner proper 10' and the friction layer 11 are produced or molded by two different extrusion molding machines, and thereafter the molded parts are united through suitable coupling method, such as method of using adhesive, method of partially melting the friction layers 11, method of using a welding device, or the like. However, such conventional methods have required troublesome working steps due to use of two molding machines. This induces increase in production cost of the weather strips. Furthermore, the above-mentioned conventional methods have failed to provide a satisfied joining between the glass runner proper 10' and the friction layers 11. It would therefore be desirable to be able to provide a device for producing a weather strip, which is free of the above-mentioned drawbacks. FR-A-2 310 207 discloses a device for producing a weather strip comprising an extrusion die having three die plates in series. The first die plate is fed with rubber material by a first extruder. Sponge rubber for forming a sealing portion is fed to the extrusion via the second die plate. Rubber material for forming an outer surface portion is fed to the extrusion via the third plate. Thus, only rubber materials are used. An object of the present invention is to provide a combination extrusion head assembly which can be used in the production of a weather strip from unvulcanized rubber material and uncured thermoplastic material as the raw materials. The present invention provides a combination extrusion head assembly as set forth in claim 1. In accordance with the invention the assembly includes a heat insulating plate having a shaping aperture through which the unvulcanized rubber material is to pass. The uncured but pasty thermoplastic material is introduced downstream of the heat insulating plate. Preferred features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic view of a weather strip production line; Fig. 2 is an exploded view of a combination extrusion head assembly which is used in the production line of Fig. 1; Fig. 3 is an enlarged sectional view of an essential part of the combination extrusion head assembly of Fig. 2; Fig. 4 is a sectional view of a weather strip which is produced by the production line of Fig. 1; Fig. 5 is a side view of a modified combination extrusion head assembly; Fig. 6 is a view similar to Fig. 4, but showing a weather strip produced by a production line in which the modified combination extrusion head assembly is installed; and Fig. 7 is a sectional view of a weather strip which is produced through a known method. DETAILED DESCRIPTION Referring to Fig. 1 of the drawings, there is shown a production line which comprises a rubber material supplier 13 from which a rubber material carrying track 15 extends to a combination extrusion head assembly 17. The rubber material supplier 13 is fed with an unvulcanized rubber material which includes suitable amounts of polymer(s), carbon, oil, vulcanizing agent, etc. As the polymer, ethylene-propylene rubber (EPDM), styrene-butadiene rubber (SBR), polychloroprene (CR), acrylonitrile-butadiene/polyvinyl chloride copolymer (NBR/PVC), chlorosulfonated polyethylene (CSM) and acrylic rubber (ACM) are used in single or combined fashion. The carbon is of the grade "MAF", "FEF" or "SRF". The oil is of paraffinic type, naphthenic type, aromatic type, or dioctyl phthalate (DOP), or dioctyl adipic acid (DOA). As the vulcanizing agent, thiazole type, thiuram type or dithiocarheminic acid guanidine type is used. Table 1 shows the mixing ratio of components of each rubber material. Referring back to Fig. 1, designated by numeral 19 is a plastic material supplier from which a plastic material carrying track 21 extends to the combination extrusion head assembly 17. That is, the plastic material supplier 19 and the above-mentioned rubber material supplier 13 are arranged in parallel with respect to the combination extrusion head assembly 17. The plastic material supplier 19 is fed with an uncured thermoplastic material, such as polyethylene (PE), polypropylene (PP) or the like. As will become apparent as the description proceeds, by simultaneously receiving the rubber material from the rubber material supplier 13 and the plastic material from the plastic material supplier 19, the combination extrusion head assembly 17 extrudes a continuous shaped strap 23 which has a layered structure. The strap from the head assembly 17 is led into a vulcanizing oven 25 and then into a cooling tunnel 27. For achieving this movement of the strap 23, a drawing machine 29 is arranged downstream of the cooling tunnel 27. The strap 23 thus cooled by the cooling tunnel 27 is cut into pieces by a cutting machine 31. The cut pieces are then neatly taken up by a take-up machine 33. Referring to Figs. 2 and 3, there is shown in detail the combination extrusion head assembly 17 by which the layered and shaped strap 23 is continuously extruded. In the drawings, denoted by numeral 35 is a cylinder barrel in which an extruding screw 37 (see Fig. 3) is installed. The cylinder barrel 35 is communicated with the rubber material supplier 13. Thus, upon rotation of the extruding screw 37, the unvulcanized rubber material, which has been already mixed in the supplier 13, flows downstream in the barrel 35. The cylinder barrel 35 has an enlarged head portion 39 in which a conical bore 39a merged with the bore of the barrel 35 is formed. The head portion 39 has at its outer side a circular recess 39c which is concentric with the conical bore 35a. Furthermore, the head portion 39 has at the circular recess 39c four threaded bolt holes 39b. Although not shown in the drawings, the wall of the cylinder barrel 35 is formed with a steam jacket for heating the unvulcanized rubber material in the barrel 35. Steam inlet and outlet hoses 41 are connected to the head portion 39 to flow steam in the steam jacket. Designated by numeral 43 is an annular inside mouth piece which is snugly received in the circular recess 39c of the cylinder barrel 35. As shown, the inside mouth piece 43 is formed with a shaping aperture 43a which is shaped to correspond to the section of a product, viz., the produced weather strip 10a (see Fig. 4). As is understood from Fig. 3, the aperture 43a is tapered so as to be smoothly merged with the conical bore 39a of the cylinder barrel head portion 39. The piece 43 is further formed with four bolt holes 43b which are mated with the four threaded bolt holes 39b of the cylinder barrel head portion 39. Attached to the inside mouth piece 43 is a circular heat insulating plate 45 which is constructed of ceramics, fluorocarbon resin or the like. The insulating plate 45 has a shaping aperture 45a which is shaped to correspond to the section of the produced weather strip 10a. This plate 45 has also four bolt holes 45b which are mated with the four bolt holes of the mouth piece 43. Attached to the heat insulating plate 45 is a circular head body 47 which has a shaping aperture 47a identical to the shaping aperture 45a of the heat insulating plate 45. This head body 47 has also four bolt holes 47b which are mated with the four bolt holes 45b of the heat insulating plate 45. As is seen from Figs. 2 and 3, the circular head body 47 is formed with a passage 47c which extends from the outer surface of the head body 47 to the shaping aperture 47a of the same. The passage 47c is communicated with the plastic material supplier 19 to be fed with the uncured plastic material. As will be understood from Fig. 2, the passage 47c is exposed to the shaping aperture 47a through three openings (no numerals), two being openings exposed to portions of the shaping aperture 47a, which portions correspond to positions where the inside lips 3a and 5a of the produced weather strip 10a (see Fig. 4) are located, and the remaining one being an opening exposed to a portion of the aperture 47a which portion corresponds to a position where a base portion 1 of the product 10a (see Fig. 4) is located. As is seen from Fig. 2, the head body 47 has an annular electric heater 49 disposed thereabout. The heater 49 is equipped with terminals 49a and 49b to which lead wires from an electric power source (not shown) are connected. Similar to this, the material carrying track 21 from the plastic material supplier 19 has an annular electric heater 51 disposed thereabout. The heater 51 is equipped with terminals 51a and 51b. Attached to the circular head body 47 is an annular outside mouth piece 53 which has a shaping aperture 53a identical to the shaping aperture 47a of the circular head body 47. The outside mouth piece 53 also has four bolt holes 53b which are mated with the four bolt holes 47b of the head 47. The cylinder barrel 35, the inside mouth piece 43, the heat insulating plate 45, the head body 47 and the outside mouth piece 53 are tightly combined by four connecting bolts 55 which are received in the mated bores 53b, 47b, 45b and 43b and screwed into the threaded bolt holes 39b of the cylinder barrel head portion 39. In the following, operation of the combination extrusion head assembly 17 will be described. During operation, the cylinder barrel 35, the head body 47 and the material carrying track 21 of the plastic material supplier 19 are kept heated at desired temperatures. Due to rotation of the extruding screw 37, the unvulcanized rubber material led into the cylinder barrel 35 from the rubber material supplier 13 is forced into the shaping aperture 43a of the inside mouth piece 43 and then into the shaping aperture 45a of the heat insulating plate 45. Thus, the rubber material extruded from the aperture 45a is forced to have a desired shape. During this extrusion process, the rubber material can keep its desired fluidity due to the heat applied thereto by the steam in the steam jacket of the cylinder barrel 35. The shaped rubber material from the shaping aperture 45a is then led into the shaping aperture 47a of the head body 47. During this process, the uncured but pasty plastic material from the plastic supplier 19 is led into the shaping aperture 47a through the above-mentioned three openings, so that three strips of the plastic material are continuously applied to three given portions of the shaped rubber material. Due to heat produced by the two heaters 49 and 51, the plastic material can keep its desired fluidity. The shaped rubber material thus applied with the three strips (which will be referred to as a continuous shaped strap 23 hereinafter) of the plastic material is forced into the shaping aperture 53a of the outside mouth piece 53 and then extruded from the combination extrusion head assembly 17. The continuous shaped strap 23 is then led into the vulcanizing oven 25 for its curing and then led into the cooling tunnel 27. The strap 23 thus cooled and hardened is then cut into pieces by the cutting machine 31 and neatly taken up by the take-up machine 33, as is seen from Fig. 1. During the above-mentioned extrusion process, the temperature of the extruding screw 37 should be kept at about 30°C, the temperature of the cylinder barrel 35 should be kept at about 30°C to 60°C, the temperature of the head portion 39 should be kept at about 40°C to 70°C, the temperature of the inside mouth piece 43 should be kept at about 40°C to 100°C, and the temperature of the head body 47 should be kept at about 120°C to 300°C. The temperature of the vulcanizing oven 25 should be kept at about 150°C to 250°C. Of course, these temperatures must be changed in accordance with the types of the rubber arid plastic materials used. Thus, when occasion demands, cooling water may be fed to the steam jacket of the cylinder barrel 35 in place of the steam. Besides the above-mentioned polyethylene resin (PE) and polypropylene resin (PP), various plastic materials may be used, which are, for example, ethylene-vinyl acetate copolymer (EVA), polyamide (PA), polyacetal (POM), polycarbonate resin, polysulfonic resin, polyvinyl chloride (PVC) and TPE resin. Furthermore, if desired, fluorine type resin (PTFE) or micro-capsules containing molybdenum disulfide, graphite, silicon oil, wax or oily material may be mixed with the plastic material. With this mixture, slidability and water repellency of the three strips (viz., the low friction layers 11) are improved. Fig. 4 shows the weather strip 10a produced through the above-mentioned process. As will be seen from this drawing, the three low friction layers 11 formed on the given surfaces of the glass runner proper 10a' are the cured three strips of the plastic material. Referring to Fig. 5, there is shown a modification 17a of the above-mentioned combination extrusion head assembly 17. Since the modification 17a is similar in construction to the above-mentioned head assembly 17, the detailed description of the modification 17a will be directed to only parts and constructions which are different from those of the head assembly 17, and the substantially same parts are denoted by the same numerals. In the modification 17a, a separate annular body 39' is used, which corresponds to the head portion 39 of the above-mentioned head assembly 17. A cylinder barrel 35' communicated with the rubber material supplier 13 is connected through a thinner pipe 35'a to a side wall of the annular body 39'. The inside mouth piece 43, the heat insulating plate 45 and the head body 47 are connected to the annular body 39' in this order. The annular body 39' has at its front face an opening (not shown) through which an elongate metal core member 57 is continuously fed into the head assembly 17a for the reason which will become clarified therein after. Another head body 48 is further employed in this modification, which is attached to the head body 47 and is similar in construction to the head body 47. A passage 48c formed in the other head body 48 is communicated with another plastic material supplier 20. The passage 48c of the other head body 48 is exposed to the corresponding shaping aperture (not shown) through two openings. These two openings are exposed to portions of the corresponding shaping aperture, which portions correspond to positions where the outside lips 12 (see Fig. 6) are located. The outside mouth piece 53 is attached to the other head body 48. The annular body 39', the inside mouth piece 43, the heat insulating plate 45, the two head bodies 47 and 48, and the outside mouth piece 53 are tightly combined by the four connecting bolts 55. In operation, the unvulcanized rubber material from the rubber material supplier 13 is led through the cylinder barrel 35' into the annular body 39' and then forced into the shaping bore (viz., the mated shaping apertures) of the head assembly 17a. In synchronization with the movement of the rubber material, the metal core member 57 is inserted into the head assembly 17a, and the uncured pasty plastic materials from the plastic suppliers 19 and 20 are led into the corresponding shaping apertures through the respective openings. Thus, the strap 23 extruded from the head assembly 17a can have such a section as shown in Fig. 6. Of course, the strap 23 is thereafter led into the vulcanizing oven 25 and the cooling tunnel 27 before being cut into pieces by the cutting machine 31. Fig. 6 shows the weather strip 10b produced by the line in which the modified head assembly 17a is used. As shown, the metal core member 57 is embedded in the glass runner proper 10b'. The three low friction layers 11 are produced by the plastic material from the plastic supplier 19, while the other two low friction layers 12 are produced by the plastic material from the other plastic supplier 20. As is understood from this drawing, by suitably selecting the positions of the material feeding openings of the two head bodies 47 and 48, it is possible to provide a united structure of the two layers 11 and 12 on each lip portion 3a or 5a.

Claims: A combination extrusion head assembly (17) for use in a weather strip production line which includes a first material supplier (13) for supplying unvulcanized rubber material and a second material supplier (19) for supplying uncured but pasty thermoplastic material, the assembly (17) comprising: a cylinder barrel (35) through which unvulcanized rubber material fed from the first material supplier (13) is to be forced to flow toward a downstream open end thereof; an inside mouth piece (43) having a shaping aperture (43a) and being attached to the downstream open end of the cylinder barrel (35); a heat insulating plate (45) having a shaping aperture (45a) and being attached to the inside mouth piece (43); a head body (47) having a shaping aperture (47a) and being attached to the heat insulating plate (45), the head body (47) having a material feeding passage (47c) with one open end exposed to a given portion of the shaping aperture (47a) of the head body (47) and the other open end to be communicated with the second material supplier (19) so that uncured but pasty thermoplastic material is fed to the said given portion through the material feeding passage (47c); an outer mouth piece (53) having a shaping aperture (53a) and being attached to the head body (47); and means (39,55) for uniting the inside mouth piece (43), the heat insulating plate (45), the head body (47), and the outside mouth piece (43) and mounting the united structure to the downstream open end of the cylinder barrel (35), so as to connect the shaping apertures (43a,45a,47a,53a) in series. A combination extrusion head assembly as claimed in claim 1, including means (41) for heating the downstream open end of the cylinder barrel (35). A combination extrusion head assembly as claimed in claim 1 or 2, including means (49) for heating the head body (47). A combination extrusion head assembly as claimed in any preceding claim, in which the said one open end of the material feeding passage (47c) is divided into at least two portions. A combination extrusion head assembly as claimed in any preceding claim, further comprising a second head body (48) having a shaping aperture and being disposed between the first-mentioned head body (47) and the outside mouth piece (53), the second head body (48) having a material feeding passage (48c) with one open end exposed to a given portion of the shaping aperture of the second head body (48) and the other open end to be communicated with a third material supplier (20) for feeding uncured but pasty thermoplastic material fed to the said given portion through the second material feeding passage (48c). A combination extrusion head assembly as claimed in claim 5, in which the said one open end of the second material feeding passage (48c) is divided into at least two portions. A combination extrusion head assembly as claimed in any preceding claim, further comprising a structure (39') which is arranged between the cylinder barrel (35') and the inside mouth piece (43) and which has an opening through which a metal core member (57) for the produced weather strip (23) is to be inserted. A weather strip production line including a first material suppier (13) for supplying unvulcanized rubber material, a second material supplier (19) for supplying uncured but pasty thermoplastic material, and a combination extrusion head assembly (17) according to any preceding claim. A method of producing a weather strip using a production line according to claim 8, comprising: (a) forcing unvulcanized rubber material from the first material supplier (13) to flow through the cylinder barrel (35) towards its downstream open end; (b) feeding uncured but pasty thermoplastic material from the second material supplier (19) to the said given portion of the shaping aperture (47a) of the head body (47) through the material feeding passage (47c); and (c) curing the extruded product in a vulcanizing oven (25).

Inventors: IMURA HIROYOSHI, MIYAMA MASAYOSHI, TOGAMI HIROSHI, YAMAGUCHI TOSHIAKI, IMURA, HIROYOSHI, MIYAMA, MASAYOSHI, TOGAMI, HIROSHI, YAMAGUCHI, TOSHIAKI, Imura, Hiroyoshi, c/o Kinugawa Rubber Ind. Co.Ltd., Miyama, Masayoshi, c/o Kinugawa Rubber Ind.Co.Ltd., Togami, Hiroshi, c/o Kinugawa Rubber Ind. Co. Ltd., Yamaguchi, Toshiaki, c/o Kinugawa Rubber Ind.
Applicants: KINUGAWA RUBBER IND, KINUGAWA RUBBER IND. CO., LTD.
Application year: 1992
Main classification: B29C47
IPC codes: B29C47, B60R13, B60J10, B29L31, B29K21, B29K101