MOLDING MANUFACTURING METHOD

Abstract: A molding manufacturing method for easily manufacturing an I-I/J-J molding which has different cross-sectional configurations in a longitudinal direction even in an undercut state, comprising the steps of extruding, through an extruding port provided in a die, a solid molding material having a predetermined cross-sectional configuration I-I using a resin material, the material (P1) of which is different from a material (P2) used for the main part of the molding, for an unnecessary part (12a) that is to be removed afterwards, and thereafter separating and removing from the main part of the molding material the unnecessary part (12a) formed of the resin material, the material (P1) of which is different from the material used for the main part of the molding.

Description: Field of the Invention The present invention relates to a production method of a long molding strip. Description of the Prior Art Lengthy strips of decorative molding are often used on exterior surfaces of marine vessels, vehicles, building materials and other general machinery and equipment. For example, windshield moldings, side moldings and bumper moldings are usually installed to the edges of the windshield openings and side surfaces of body panels of automobiles and to bumpers thereof. These moldings usually consist of lengthy extruded resin strips extruded through an extruding dies wherefrom said extruded resin molding strips are extruded with a specific cross-sectional shape before being cut to a prescribed unit length. To produce various types of these kinds of moldings, different molding strip production methods have been disclosed wherein a molding strip is extruded in a specific cross-sectional shape before removing a portion of said molding strip by passing said strip through a prescribed cutting process, thus making the cross-sectional shape of the molding strip vary along its length. For example, the production methods disclosed in Japanese Utility Model Laid-Open Publication JP-U-32915/1988, Japanese Utility Model Laid-Open Publication JP-U-128412/1989 and Japanese Utility Model Laid-Open Publication JP-U-13⊘816/1989 call for removal, by a cutting process, of the inner peripheral portion of the decorative part of a molding strip which cover up the edges of the windshield glass of an automobile and for equipping a dam portion along the cut. With some bumper moldings, the molding strip and the mounting pieces which support the molding strip exposing to the outer from the back are extruded integrally before removing a superfluous portion of the mounting pieces by a cutting process so as to set the remaining mounting pieces into the bumper surface for fixing the molding strip onto the bumper. Production methods are disclosed in Japanese Patent Laid-Open Publication JP-A-112845/1983 and Japanese Utility Model Laid-Open Publication JP-U-76⊘57/1987 wherein a molding strip is extruded in a hollow sectional shape for the purpose of making the molding of lighter in weight but providing resin-filled ribs several sections along the length as reinforcing ribs. Said resin-filled ribs functioning as reinforcing ribs work to maintain a uniform, solid external appearance, therefore, such reinforcing ribs are often positioned at the bent sections of a molding. Hollow moldings are extruded, for example, in a C-shaped section and the reinforcing ribs are formed to fill the hollow section of the C-shape at prescribed distances. Further,in regard to the windshield molding strips for automobiles, Japanese Patent Laid-Open Publication JP-A-291721/1988 discloses a windshield molding strip to be installed to cover the upper and side edges of a windshield glass and Japanese Patent Laid-Open JP-A-289716/1989 etc., disclose an automotive windshield molding strip equipped with a conduit groove which functions as a rainwater flume. With conventional production methods for molding provided with the flume, a molding strip with the flume and one without such flume are separately extruded before joining the two strips together using joints or the like. In fact, however, with conventional molding production methods employing a cutting process for the above-mentioned purpose, the potential for shaping in the cutting process is limited and, especially, a cutting process to hollow out the section shape by undercutting is generally impossible. Also, when the cutting length is in a longer range, very large sized dies become necessary. Furthermore, when forming the filled ribs to function as reinforcing ribs with a molding, "padding" is placed at several sections of a molding, but with such conventional production methods, an additional process becomes necessary to join separate parts which were extruded separately. In other words, with conventional production methods of the above-mentioned type of molding, it has not been possible to integrally or in series form the total length of a molding equipped with resin-filled ribs to work as reinforcement ribs, thus resulting in low productivity. Moreover, when providing equipping a molding with a flume using conventional methods, some component molding parts become necessary and, to make the situation even more complicated, the production processes of the molding become more complex. However, with the windshield glass molding disclosed in Japanese Patent Laid-Open Publication JP-A-195⊘32/1989, the molding strip is extruded all the way along the entire length of said molding strip in a fixed cross-sectional shape involving a projecting dam which is then cut and removed at sections where it is unnecessary. Nevertheless, with this type of molding, sharp edges remain on the cut face, requiring a post-finishing process to dull the edges, with the result that the surface of the cut section has a different appearance from that of sections where cutting has not been performed. The present invention consequently intends to provide a moulding production method wherewith superfluous portions can be removed without using the cutting process and cross sectional shapes which hitherto have been difficult to achieve such as an under-cut shape can be chosen comparatively freely under an easier processing method. Moreover, the present invention intends to provide a production method of a moulding which can be easily extruded integrally throughout the entire length, including the resin filled ribs to function as reinforcing ribs. The present invention further intends to provide an efficient production method of a moulding provided with a flume to work as a rainwater conduit integrally throughout the whole length. FR-A-2431644 discloses a moulding strip of constant cross-section and with removable beading. In order to achieve the above, the present invention provides a method of producing a moulding strip by extruding the moulding strip through an extrusion port provided in dies of prescribed cross-sectional shape before completely removing a superfluous portion from the body of said moulding strips to vary the cross-sectional shape of said moulding strip along its length, the method comprising the steps of: supplying a first material via a first channel; alternately supplying a second material compatible with the first material and a third material incompatible with the first material via a second extrusion channel to thereby form a moulding strip having a plurality of superfluous portions formed from the third material and separated from one another by portions formed from said second material; and removing said superfluous portions from the body section. The superfluous portion may be separated from the moulding strip by undercutting. Several blocks of superfluous prescribed lengths throughout the length of the moulding strip may be formed and removed, thus providing several blocks of hollow sections and resin-filled sections one after the other at prescribed distances throughout the length of the moulding strip. The moulding strip may be cut at the resin-filled sections at both ends so that both ends become resin filled closed walls of a unit length. A moulding strip of partially different cross-sectional shapes depending on its section may be integrally and continuously extruded through a varying extrusion port by shifting the relative positions of multiple dies when extruding the sections where removal of the superfluous portion is not carried out during a continuous extrusion moulding process for a total length of the moulding strip using multiple sets of dies for the extruder. By use of these measures in this invention, removal of superfluous parts can be accomplished by a separation process without requiring a cutting process, thus improving forming ease and providing more optional choices of extruded shapes as compared with conventional methods involving cutting processes, and the total length of a lengthy moulding strip can be extruded integrally and continuously. In particular, a lengthy moulding strip having a cross-sectional shape varying continuously along the length of the strip may be extruded. In the drawings:- Fig. 1 is an inclined explanatory sketch drawing of a moulding strip extruded under an exemplary embodiment of this invention. Fig. 2 is an inclined sketch drawing of an example of the dies for extrusion of the moulding strip as shown in Fig. 1. Fig. 3 is the horizontal A-A section of the drawing as in Fig. 2. Fig. 4 is the horizontal B-B section of the drawing as in Fig. 2. Fig. 5 is the C-C cross-section of the drawing as in Fig. 4. Fig. 6 is the D-D cross-section of the drawing as in Fig. 4. Fig. 7 is a cross-sectional view showing the shifts of the dies indicated in Fig. 3. Fig. 8 is a cross-sectional view showing the shifts of the dies indicated in Fig. 4. Fig. 9 is a cross-sectional view showing the shifts of the dies indicated in Fig. 5. Fig. 1⊘ is a cross-sectional view showing the shifts of the dies indicated fin Fig. 6. Fig. 11 is an inclined explanatory sketch drawing of the molding strip as is shown in Fig. 1, right after extrusion but before the removal process of the superfluous portions. Fig. 12 is the E-E cross-section of the drawing as in Fig. 11. Fig. 13 is an inclined explanatory sketch drawing of the molding strip as is shown in Fig. 11 from which the superfluous portions have been removed. Fig. 14 is the F-F cross-section of the drawing as in Fig. 13. Fig. 15 is the G-G cross-section of the drawing as in Fig. 13. Fig. 16 is an inclined explanatory sketch drawing of another example of the molding strip extruded under the production method of this invention. Fig. 17 is an inclined explanatory sketch drawing of some other example of the molding strip extruded under the production method of this invention. Fig. 18 is an inclined explanatory sketch drawing of the molding strip as is shown in Fig. 17, right after extrusion but before the removal process of the superfluous portions. Fig. 19 is the H-H cross-section of the drawing as in Fig. 18. Fig. 2⊘ is an inclined explanatory sketch drawing of the molding strip as is shown in Fig. 18 from which the superfluous portions have been removed. Fig. 21 is the I-I cross-section of the drawing as in Fig. 2⊘. Fig. 22 is the J-J cross-section of the drawing as in Fig. 20. Referring more particularly to the exemplary embodiments of this invention using the drawings, Fig. 1 shows an example of molding strip 1 which can be extruded under the production method of this invention, which is to be installed to the bumper of an automobile. The moulding strip 1 has a decorative body 11 and a mounting piece 12 supporting the decorative body 11 from the back. The mounting pieces 12 are to be set into the surface of the bumper of an automobile for fixture of the molding onto the bumper so as to expose the decorative body 11 to outer side. The molding strip 1 consists of fully-equipped sections 1A and removal sections 1B continuously ranging along its length alternatively. Such fully-equipped sections 1A are integrally provided with both said decorative body 11 and mounting pieces 12 while the removal sections 1B are provided with the decorative body 11 only, from which the mounting pieces have been removed. Each decorative body 11 is made of a transparent ionomer resin P2 extruded in a prescribed C-shaped cross-section throughout its whole length including the fully-equipped sections 1A and the removal sections 1B. Further, laminated metallic films 11a formed in a mating C-shaped cross-section are embedded into the outer area of said decorative body 11, where mounting pieces 12 are extruded in a cross-sectional arrow shape integrally projecting from behind the decorative body 11 and are made of the same transparent ionomer resin P2. The mounting pieces 12 are located at prescribed intervals along the length of the molding strip 1 and each mounting piece 12 is of a prescribed short length in the longitudinal direction. The section between two mounting pieces 12 has a hollow section from which the mounting pieces 12 have been removed. Meanwhile, as referred to later, the molding strip right after extrusion also has the superfluous portions 12a (see Fig. 11) which are separated and removed from said decorative body 11 later. Meanwhile, the mounting pieces 12 may be extruded using a different kind of resin from that for the decorative body 11 insofar as the former resin has compatibility with the latter. Referring more particularly to an exemplary facility for extrusion of a molding strip 1 of said structure, the molding strip can be produced by extruding workpiece strips through a die (extruding dies) 2, shown in Fig.2, before passing workpiece strips through the removal process referred to later. The dies 2 comprised of a stationary first die 21 and a second die 22 which is movable for fitting to the first die 21 in parallel with it, wherewith the material of the extrusion resin extruded through a extrusion port 211 provided in the first die 21 can be switched over by parallel shifting of the second die 22. As shown in Fig. 2, Fig. 3 and Fig. 6, the first die 21 is provided with an extrusion port 211 opening on its front end face and is also provided with one mounting piece extrusion channel 212 and two decorative body extrusion channels 213, 213 continuing to the inner end of the extrusion port 211. The mounting piece extrusion channel 212 opens into the center of the extrusion port 211 and the two decorative body extrusion channels 213, 213 are respectively positioned on either sides of the mounting piece extrusion channel 212 and respectively open into the peripheral area of the extrusion port 211. One of these two decorative body extrusion channels 213, 213 extends and turns toward the side surface of the first die 21 and the supply source of a resin P2 (a transparent ionomer resin) which is omitted from the drawing is connected to the external supply port thereof, while the other hand decorative body extrusion channel 213 branches off from an intermediate point of the one hand decorative body extrusion channel 213 connected to said resin supply source extending over the mounting piece extrusion channel 212 before opening out to the extrusion port 211. At the base position of said mounting piece extrusion channel 212, a reservoir 214 of prescribed cavity dimensions is provided and the second die 22 which faces said reservoir 214 is fitted, allowing horizontal reciprocal motion perpendicular to the direction of extrusion. The second die 22 is provided with a pair of switch-over channels 221, 221 positioned in parallel along the direction of extrusion which are so structured that one of them alternatively opens into the cavity of the reservoir 214 in said first die 21 and the horizontal reciprocal shifts of said second die 22 determine the choice between the two switch-over channels 221, 221. Moreover, said first die 21 is provided with a pair of material supply channels 215, 215 and a pair of material exhaust channels 216, 216 facing each other in the up/down direction across the switch-over channels 221, 221 in the second die 22. The material supply channels 215, 215 are provided with tubs 215a, 215a which always open to the switch-over channels 221, 221 of said second die 22. Through one of these pair of material supply channels 215, 215, the resin material P2 is fed, while through the remaining material supply channel, the resin material P1 is fed, which is of a different kind from the resin material P2. A PVC resin, for example, can be used as the resin material P1 which is incompatible with the resin material P2, while, the material exhaust channels 216, 216, respectively, are arranged so as open alternatively to the switch-over channels 221, 221, respectively, of said second die 22 and the bottom surface of the first die 21. Referring more particularly to an exemplary embodiment of this invention for extrusion of said molding strip 1 using said facility, firstly, when extruding the fully equipped sections 1A comprising of the decorative body 11 and the mounting pieces 12 integrally, the first die 21 and the second die 22 are shifted to the relative positions as shown in Fig. 7 to Fig. 1⊘. With this shift, between the two switch-over channels 221, 221 provided in the second die 22, the one switch-over channel 221 in the open connection with the material supply channel 215 feeding the resin material P2 (the right side one in the drawing) opens into the reservoir 214 in the first die 21, while the other switch-over channel 221 in the open connection with the material supply channel 215 feeding the resin material P1 (left side one in drawing) remains away from reservoir 214, being closed, but opens into one of the material exhaust channels 216, 216. With this layout, as shown in the drawings by arrows, resin material P2 fed into one of the change-over channels 221 (right side one in drawing) of the second die 22 via one of the material supply channels 215, 215 (right side one in drawing) of the first die 21 passes through the mounting piece extrusion channel 212 of the first die 21 before extruding through the central section of the extrusion port 211. As a result, the mounting pieces 12 of the molding strip 1 are formed by extrusion of the resin material P2. At this time, resin material P2 is constantly supplied through the decorative body extrusion channels 213, 213 in the first die 21 and the resin material P2 is extruded through the peripheral area of the extrusion port 211 via the both decorative body extrusion channels 213, 213. Consequently, as per the cross-section shown in the drawing in Fig. 11, the decorative body 11 and the mounting pieces 12 are integrally formed by extrusion of the resin material P2 thus forming the fully equipped section 1A of the molding strip 1. Meanwhile, the resin material P1 fed into the other switch-over channel 221 (left side one in drawing) in the second die 22 via the other material supply channel 215 (left side one in drawing) in the first die 21 bypasses the reservoir 214 and is exhausted through the material exhaust channel 216. Next, when extruding the separating sections 1B of the molding strip 1, the first die 21 and the second die 22 are shifted to the relative positions as shown in Fig. 3 to Fig. 6. By this shift, between the two switch-over channels 221, the one switch-over channel 221 (the left side one in the drawing) in the open connection with the material supply channel 215 feeding the resin material P1 opens into the reservoir 214 in the first die 21, while the other switch-over channel 221 (right side one in drawing) in open connection with the material supply channel 215 feeding the resin material P2 remains away from reservoir 214, being closed, but opens into the other side of the material exhaust channel 216. With this layout, as shown in the drawings by arrows, resin material P1 fed into the other switch-over channel 221 (left side one in drawing) in the second die 22 via the other material supply channel 215 (left side one in drawing) in the first die 21 passes through the mounting piece extrusion channel 212 in the first die 21 before extruding through the central section of the extrusion port 211. Thus, the mounting piece sections 12 of the molding strip 1 are formed by extrusion of the resin material P1 as superfluous portions 12a. At this time, resin material P2 is constantly fed into the decorative body extrusion channels 213, 213 in the first die 21 and the resin material P2 is extruded through the peripheral area of the extrusion port 211 via the both decorative body extrusion channel 213, 213. Consequently, as shown in Fig. 12, the decorative body 11 is formed, surrounding said superfluous sections 12a, by extrusion of different resin material P2, independently. At this time, the resin material P2 fed into the other switch-over channel 221 (right side one in drawing) in the second die 22 via the other material supply channel 215 (right side one in drawing) in the first die 21 bypasses the reservoir 214 to be exhausted through the material exhaust channel 216. When actually extruding the molding strip 1, as shown in Fig. 11, the fully equipped sections 1A and removal sections 1B are extruded alternatively, a fully equipped section 1A is extruded for a short prescribed length before a removal section 1B is extruded for a prescribed length and a fully equipped section 1A is extruded again, and such cycle is repeated. At this time, the decorative body 11 is extruded in the same cross-sectional shape by the same resin material P2 throughout the entire length of the molding strip 1 consisting of the fully equipped sections 1A and the removal sections 1B. While the mounting pieces 12 are extruded integrally with the decorative body 11 using the resin material P2 throughout the short length within the range of the fully equipped section 1A, but at the border with the separating section 1B, the resin material is changed to P1 from P2. In other words, while extruding the separating section 1B, the section corresponding to the mounting piece 12 is extruded using resin material P1 to form a virtually resin-filled section which actually becomes the superfluous portion 12a which is incompatible with and removable from the decorative body 11. After production work for molding strips under the above-mentioned extrusion process, as shown in Fig. 13, the superfluous portions 12a are separated and removed from the removal sections 1B. Thus, the fully equipped section 1A shown as Fig. 14 and the removal section shown as Fig. 15 are formed to become the molding strip 1 of the final shape. Although the superfluous portions 12A of this exemplary embodiment are extracted forcibly from the under-cut shape, no functional or dimensional defects are anticipated and, especially, when separating and removing the superfluous portions 12a after a cooling process, removal can be effected very easily and smoothly. Also, if the superfluous portions 12a are formed by a water soluble resin, the cooling process in a water tank can melt away the superfluous portions 12a to complete the removal process simultaneously. Meanwhile, said removal process of the superfluous portions 12a can be carried out either before or after cutting the molding strips into unit lengths. When using said extrusion methods, since the superfluous portions can be easily separated and removed without the use of cutting processes, under-cut shape extrusion or the like can be freely adopted, thus giving more optional choices for extrusion shapes. Referring next to the molding strip 3 shown in Fig. 16 which forms a molding to cover the windshield openings in the body panel of an automobile and which can be similarly produced under an embodiment of this invention, with this molding strip 3, a decorative body 31 made of prescribed resin material P1 such as PVC is supported by a metallic mount 32 to constitute the molding strip and said mount 32 is mounted around the windshield openings of an automobile to fix the decorative body 31 in position. The fully equipped section 3A of said molding strip is extruded in a prescribed rectangular section throughout its entire length while the removal section 3B is provided with grooved rainwater conduit 33 provided along the prescribed length. The grooved rainwater conduit 33 provided in the removal section 3B has a wedge-shaped cross section and the groove is tentatively extruded forming a superfluous portion 31a using similar dies (extruder dies) to the aforementioned ones. In other words, the superfluous portion 31a is formed by extrusion of some other resin material P2 incompatible with the resin material P1 which forms the decorative body 31. From the molding strips thus produced, said superfluous portions 31a made of said incompatible resin material P2 are removed as shown in the drawing under a prescribed removal process to become the molding strip 3 of the final shape. By use of said extrusion method under the second exemplary embodiment of this invention, similar functions and effects can be attained as those from the extrusion method under the aforementioned first exemplary embodiment of this invention. Referring further to the molding strip 4 for automotive applications as shown in Fig. 17, Fig. 18 and Fig. 19 as is obtained by an extrusion method under this invention, this consists of the decorative body 41 with a C-shaped cross-section positioned to be exposed externally and the reinforcing rib 42 integrally filling a distance of the C-shape sectioned decorative body 41 by the resin material. The molding strip 4 comprises along its length, resin-filled sections 4A and hollow sections 4B in series, the resin-filled sections 4A being of a resin-filled cross-section integrally provided with both decorative body 41 and reinforcing ribs 42 while said hollow sections 4B consist only of the hollow-shaped decorative body 41 without the reinforcing ribs 42. The decorative body 41 is formed by a transparent ionomer resin P2 and extruded in the same cross-section (C-shaped section) throughout the whole length including the distances of the resin-filled sections 4A and of the hollow sections 4B. Also, laminated metallic films with a mating C-shaped section are embedded into the outer periphery of said decorative body 41. While the reinforcing rib 42 consists of a rib formed by filling a distance of the hollow section with the same transparent ionomer resin forming the decorative body 41. The reinforcing ribs 42 are located at prescribed intervals along the length of the molding strips with a prescribed short length in the longitudinal direction. Sections between two reinforcing ribs 42, 42 are formed into a hollow C-shaped section surrounded by the internal surfaces of the decorative body 41. The section corresponding to the hollow section between two reinforcing ribs 42, 42 is initially extruded to form a virtually resin-filled section which actually becomes the superfluous portion 42a which is incompatible with and later removable from the decorative body 41. When actually extruding said molding strips 4, as shown in Fig. 18 to Fig. 22, resin-filled sections 4A and hollow sections 4B are extruded alternatively, a hollow section 4B forming virtually resin filled section being extruded for a prescribed length before a resin filled section 4A is extruded for a prescribed short distance and a hollow section 4B is extruded again, and such cycle is repeated. In other words, the decorative body 41 is extruded in a uniform cross-section throughout the whole length of the molding strip 4 comprised of the resin-filled sections 4A and hollow sections 4B using the same resin material P2. While the reinforcing ribs 42 are extruded in the resin-filled ribs integrally with the decorative body 41 using the same resin material P2 over the distance of the resin-filled sections 4A but at the border into the hollow sections 4B, the material is changed from the resin material P2 to P1 thus forming virtually resin-filled sections which actually become superfluous portions 42a which are incompatible with and later removable from the decorative body 41. After obtaining the molding strips by the aforementioned extrusion, as shown in Fig. 2⊘, the superfluous portions 42a are separated and removed from the hollow section 4B. Thus, the resin-filled sections 4A as shown in Fig. 21 and the hollow sections 4B as shown in Fig. 22 are formed into the molding strip 4 of final shape. Separation and removal of the superfluous portions 42a can be carried out very easily and smoothly when done after the cooling process. Meanwhile, said separation process of the superfluous portions 42a can be carried out either before or after cutting the molding strips into unit lengths. Under said extrusion method, the decorative body 41 finally forming hollow sections is apparently extruded together with virtually resin-filled sections which actually become superfluous portions 42a, and thus the whole length of the molding strips is extruded continuously and together. When cutting said molding strips into unit lengths, by cutting around the centers of the resin-filled sections 4A as shown by the broken line 4C in Fig. 17, hollow cross-sectioned molding strips with both ends closed can be obtained. Industrial Applicability The production method under this invention can be applied to all types of lengthy molding strips for use with marine vessels, construction materials and other general machinery and equipment and is particularly suitable for continuous extrusion of molding strips consisting of alternative hollow sections and filled sections without need for a cutting process for removal of the superfluous portions.

Claims: A method of producing a moulding strip (1) by extruding the moulding strip through an extrusion port provided in dies of prescribed cross-sectional shape before completely removing a superfluous portion (12a) from the body of said moulding strips to vary the cross-sectional shape of said moulding strip along its length, the method comprising the steps of: supplying a first material (P2) via a first channel; alternately supplying a second material (P2) compatible with the first material and a third material (P1) incompatible with the first material (P2) via a second extrusion channel to thereby form a moulding strip having a plurality of superfluous portions (12a) formed from the third material (P1) and separated from one another by portions formed from said second material (P2); and removing said superfluous portions (12a) from the body section (11). A method according to claim 1, wherein said superfluous portion (12a) is forcibly removed from an under-cut enclosure of the moulding strip (1). A method according to claim 1, wherein cutting of moulding strips (1) into unit lengths is performed within the extent of the filled sections positioned at prescribed intervals so as to provide moulding strips (1) with both longitudinal ends closed. A method according to claim 1, further comprising the step of: when extruding the part from which removal of the superfluous portion (12a) is not performed, moving said multiple dies relative to each other so as to change the cross-section of the extrusion port, thus extruding moulding strips having partially different cross-sectional shapes continuously and integrally through the entire moulding.

Inventors: YADA YUKIHIKO, YADA, YUKIHIKO, YADA, YUKIHIKO 8-6, AZA-KOMORI
Applicants: TOKAI KOGYO CO LTD, TOKAI KOGYO KABUSHIKI KAISHA
Application year: 1993
Main classification: B60J1
IPC codes: B60J10, B29C47, B60J1, B60R13, B29C69, B29L31