JP2004074441A - Manufacturing method for weather strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an undesired bulging shape of a weather strip caused by the contact with a feed roller in a manufacturing method for a weather strip wherein a core material is embedded in a foamed rubber part. <P>SOLUTION: When the weather strip extruded from an extruder is allowed to run through a heating apparatus to be vulcanized while the undersurface of the weather strip is supported by a plurality of feed rollers arranged so as to leave an interval in an extrusion direction, the central support part 42 of each of the feed rollers 24a is constituted of annular protruded parts 48 divided into a plurality of parts laterally by a peripheral direction groove 46 in order to reduce the contact area with the rubber 15 of each of the feed rollers 24a. The weather strip W is fed while the undersurface of the core material embedded part is supported by a plurality of the protruded parts 48. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a weather strip for sealing an opening of a vehicle body of an automobile or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a weather strip for sealing a vehicle body opening such as a door opening and a trunk opening of a vehicle, a mounting having a substantially U-shaped cross section is mounted on a flange provided on a vehicle body opening edge or a door edge. A base, and a hollow seal portion projecting from the mounting base and compressed between the vehicle body and the door when the door is closed to exhibit a sealing function, and a plurality of holding lips holding the flange inside the mounting base. There is a weatherstrip provided.
[0003]
FIG. 5 shows an example of this, and this weather strip is used for the trunk portion of the automobile shown in FIG. As shown in FIG. 5, the weather strip includes a mounting base 14 having a substantially U-shaped cross section in which a metal core material 12 is embedded, and a hollow seal portion 16 protruding from the mounting base 14. A holding lip 20 is provided inside the base portion 14, and is attached to the flange 4 provided on the vehicle body opening edge 2 by the holding lip 20.
[0004]
Conventionally, in such a weather strip, the hollow seal portion is made of sponge rubber in order to secure good sealing performance due to compression deformation, while the mounting base in which the core material is buried is not used for securing the removal force from the flange. Made of foamed solid rubber.
[0005]
[Problems to be solved by the invention]
In recent years, with the demand for weight reduction of vehicles, weight reduction has also been required for weather strips. In order to reduce the weight, it is conceivable that the mounting base made of solid rubber is formed of foamed rubber. However, since the mounting base needs to secure the pulling force from the flange as described above, the same sponge as the hollow seal part is used. It cannot be made of rubber. Therefore, it is desirable that the mounting base is formed of foamed rubber (solid foamed rubber) having higher hardness. It has been proposed to form a foamed rubber for a mounting base from a rubber composition obtained by blending the foaming agent with a base rubber.
[0006]
However, it has been found that when the mounting base in which the core material is buried is formed of foamed rubber as described above, a bulge shape partially different from the regular shape is produced in the manufacturing process.
[0007]
More specifically, as shown in FIG. 7, this type of weather strip is continuously extruded into a predetermined cross-sectional shape using an extruder 22, and the extruded continuous body W is spaced apart in the extrusion direction. It is manufactured by running inside the heating device 26 and vulcanizing while supporting the lower surface with the plurality of transport rollers 24 arranged in the above. The cross-sectional shape of the extruder 22 when it is extruded from the base 28 is such that the mounting base 14 is flat as shown in FIG. 8, and the lower surface of the flat mounting base 14 is held as shown in FIG. In order to prevent the lip 20 from being crushed before being cured by vulcanization, the center of the lower surface of the mounting base 14 without the holding lip is conveyed while being floated in the air while being supported by the conveying rollers 24x.
[0008]
As shown in FIG. 10, the above-mentioned bulge shape 100 occurs at the center of the lower surface of the mounting base 14 with which the transport roller 24x abuts. Further, as shown in FIG. The bulges 100 are generated on the lower surface of the portion where the core material 12 is buried, while the bulge 100 is vulcanized in a regular shape on the lower surface of the portion where the core material is not provided, where they are intermittently arranged at predetermined intervals in the center portion. Turned out to be.
[0009]
From these points, the present inventors considered the cause of the occurrence of the bulge shape as follows. That is, generally, the rubber surface before vulcanization has tackiness, and the core metal and rubber do not adhere. In such a situation, in the present case, the core material is buried in the foamed rubber, and the foamed rubber is softer than the non-foamed solid rubber. It was considered that the swelling shape 100 was caused by the stretching as shown in FIG. 12 due to the contact with the transport roller 24x.
[0010]
The present invention has been made in view of the above points, and provides a method of manufacturing a weatherstrip that can suppress occurrence of an undesired bulging shape by modifying the shape of a transport roller. Aim.
[0011]
[Means for Solving the Problems]
The present inventor focused on reducing the contact area with the rubber of the transport roller from the above considerations, and changed the shape of the transport roller to reduce the contact area with the rubber, regardless of the adhesiveness of the rubber surface, The inventors have found that the occurrence of an undesired bulging shape due to the stretching of the transport roller is suppressed, and have completed the present invention.
[0012]
That is, the present invention relates to a method for producing a weatherstrip comprising a foamed rubber portion and a core material embedded in the foamed rubber portion, wherein the rubber material to be the foamed rubber portion is formed by using an extruder to form the core. A step of continuously extruding the material in a predetermined cross-sectional shape together with the material, and vulcanizing the extruded continuum by running in a heating device while supporting the lower surface with a plurality of transport rollers arranged at intervals in the extrusion direction. And a support portion for supporting the lower surface of the core material via a rubber layer having a required thickness, wherein the support portion has a flat, linear, or point-like lower surface portion of the rubber layer. And a plurality of convex portions that abut against and support the continuous body while supporting the lower surface of the core material embedded portion with the plurality of convex portions.
[0013]
In this way, the support portion of the transport roller that supports the lower surface of the core material embedded portion in the foamed rubber portion is not a single and wide convex portion as in the related art, but is configured by a plurality of divided convex portions, The contact area with the rubber is smaller than in the related art, and the stretching of the rubber layer by the transport roller is reduced, and therefore, the occurrence of an undesired bulge is suppressed.
[0014]
In the manufacturing method of the present invention, the weather strip includes a mounting base having a substantially U-shaped cross-section and having a flange holding lip inside thereof, and a sealing portion made of sponge rubber protruding from the mounting base. Wherein the mounting base is the foamed rubber portion made of foamed rubber having a specific gravity greater than that of the sponge rubber, the core material is embedded in a substantially U-shaped cross section, and the mounting base is extruded in a flat state. Extruded from the machine, run through the heating device while supporting the center of the lower surface of the extruded mounting base with the support portion of the transport roller, and after vulcanization, bending the mounting base together with the core material into a U-shaped cross section. It may be formed.
[0015]
In the present invention, the support portion of the transport roller may be formed of a plurality of annular convex portions divided in a width direction by a circumferential groove. In this case, the lower surface flat portion of the rubber layer is supported in a planar or linear manner at each peripheral edge of the plurality of annular convex portions.
[0016]
In the present invention, the support portion of the transport roller may be formed in a gear shape divided into a plurality of pieces in a circumferential direction by a width direction groove. In this case, the lower surface flat portion of the rubber layer is supported in a planar or linear manner by the convex portions uniformly arranged in the circumferential direction corresponding to the teeth of the gear.
[0017]
In the present invention, the support portion of the transport roller may include a plurality of protrusions arranged at predetermined intervals in a circumferential direction and a width direction. In this case, the lower surface flat portion of the rubber layer is supported in a point-like manner by the plurality of protrusions.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. Here, a weather strip attached around the vehicle body opening shown in FIG. 5 will be described as an example.
[0019]
First, the weather strip to be manufactured will be described. This weather strip is attached to the peripheral edge 2 of the opening in the trunk room 1 of the automobile shown in FIG. 6 and seals between the lid 3 which is a trunk lid, and has a metal core material 12 embedded therein. A mounting base 14 having a substantially U-shaped cross section, a hollow seal portion 16 protruding from the upper surface of the mounting base 14 and abutting on the peripheral edge of the lid 3, and a seal protruding outward from the mounting base 14 and abutting on the vehicle body panel And a lip 18. A plurality of holding lips 20 for holding the flange 4 projecting from the vehicle body opening edge 2 are provided inside the mounting base 14. The holding lips 20 protrude in pairs from opposite surfaces inside the U-shape of the mounting base 14, and are provided so as to sandwich the flange 4 between the upper and lower two pairs of holding lips 20.
[0020]
The hollow seal portion 16 and the seal lip 18 are made of conventionally used sponge rubber (specific gravity 0.45 to 0.80), and the mounting base 14 including the holding lip 20 has a specific gravity larger and finer than the sponge rubber. It is made of a high-hardness foamed rubber (foamed solid rubber) which has air bubbles and therefore has a higher hardness than the sponge rubber. The specific gravity of the high-hardness foamed rubber is preferably 0.9 to 1.0, and the specific gravity is smaller than that of a conventional solid rubber having a specific gravity of 1.0 to 1.2. ing.
[0021]
As the high hardness foamed rubber, those formed from a rubber composition obtained by compounding a rubber-coated foaming agent with a base rubber are preferable. Since the dispersibility in the base rubber can be enhanced by coating the foaming agent with the rubber in this manner, even when a foaming agent having a small particle size is used, a foamed rubber which is uniformly foamed can be obtained. Here, as the base rubber, usually, ethylene propylene diene copolymer rubber (EPDM) is suitably used. As the coating rubber, the base rubber is used to further improve the dispersibility of the foaming agent, and to suppress foaming inhibition by the coating layer in a state similar to the absence of the coating layer around the foaming agent at the time of molding. The same type of rubber as above, that is, EPDM rubber is preferably used. The EPDM rubber used for the coating preferably has a lower Mooney viscosity than the base rubber in order to improve the kneading property and the dispersibility when kneading into the base rubber. It is preferable to use an EPDM rubber having a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 30 to 50 at room temperature. As the foaming agent, those having a small particle size are preferably used in order to form fine closed cells. As a method of coating the foaming agent with rubber, a method of mixing the coating rubber with the foaming agent using a mixer such as a kneader, etc. The rubber composition has a melting temperature. It is preferable to blend a polyolefin such as polyethylene at 100 to 110 ° C., whereby the product hardness can be maintained without deteriorating the kneading property and the extrudability.
[0022]
Next, a method for manufacturing a weather strip according to the embodiment will be described.
[0023]
As shown in FIGS. 7 and 8, using an extruder 22, a sponge rubber material for forming the hollow seal portion 16 and the seal lip 18 and a high-hardness foamed rubber material for forming the mounting base portion 14 are formed. The core 12 is continuously extruded with a predetermined cross-sectional shape, and at this time, the mounting base 14 is extruded with the core 12 buried in a flat state. Then, the extruded weather strip W is run in the heating device 26 while supporting the lower surface with the plurality of transport rollers 24 arranged at intervals in the extruding direction, and thus floating in the air.・ Vulcanize.
[0024]
In the present embodiment, the transport roller 24a shown in FIG. 1 is used as the transport roller for vulcanization. The transport roller 24a includes both side supporting portions 40, 40 for supporting both ends of the flat mounting base 14, and a central supporting portion 42 for supporting the center of the lower surface of the mounting base 14, and both sides of the central supporting portion 42. Are provided with circumferential grooves 44, 44 for allowing the holding lip 20 to escape. The central support portion 42 is a support portion that supports the lower surface of the core member 12 via the thin rubber layer 15, and includes two annular convex portions 48, 48 divided in the width direction (axial direction) by the circumferential grooves 46. Become. The convex portion 48 has a short columnar shape, and a peripheral surface thereof abuts and supports a flat lower surface of the rubber layer 15 in a planar shape. Therefore, in this case, the embedded portion of the core member 12 is supported in a planar manner at two places in the width direction by the central support portion 42, and is more than the central support portion 42x of the conventional transport roller 24x shown in FIG. Even the contact area has been greatly reduced.
[0025]
FIG. 2 shows a transport roller 24b used in another embodiment. In this case as well, the central support portion 42 of the transport roller 24b is composed of annular convex portions 48, 48... Divided in the width direction by a plurality of circumferential grooves 46. In this embodiment, the contact area with the rubber layer 15 is reduced. To further reduce the size, the peripheral edge of the annular convex portion 48 is sharpened so as to linearly contact and support the rubber layer 15. In order to reduce the load on each of the annular projections 48, the number of projections is increased as compared to the example shown in FIG. It is provided as a bellows-like portion having a groove 46 as a valley alternately and repeatedly.
[0026]
FIG. 3 shows a transport roller 24c used in still another embodiment. In this case, the central support portion 42 of the transport roller 24c has a gear shape divided into a plurality in the circumferential direction by the width direction groove 50, and includes convex portions 52 equally arranged in the circumferential direction corresponding to the gear teeth. The lower flat portion of the rubber layer 15 is linearly abutted and supported. In this case, the convex portion 52 corresponding to the tooth of the gear is tapered, that is, formed in a triangular cross-section, but instead of this, the lower surface of the rubber layer is brought into planar contact with and supported by a rectangular cross-section. Is also good. Further, in this case, each projection 52 is provided in parallel with the axial direction of the roller 24c, but may be inclined in the circumferential direction like a bevel gear.
[0027]
FIG. 4 shows a transport roller 24d used in still another embodiment. In this case, the central support portion 42 of the transport roller 24d is composed of a plurality of barbed projections 54, 54... Arranged at predetermined intervals in the circumferential direction and the width direction. The flat lower part is abutted and supported in a point-like manner, and the contact area with the rubber is further reduced. The center support portion 42 having such projections 54 can be manufactured by fixing pins at predetermined intervals on the peripheral surface of the cylindrical portion.
[0028]
The configuration for reducing the contact area with the rubber in this way is not limited to the above examples.For example, by providing various irregularities on the peripheral surface of the central cylindrical portion of the transport roller, The contact area can also be reduced.
[0029]
After vulcanizing in the heating device 26 while supporting the lower surface of the weather strip W using the transport rollers 24a to 24d described above, it is cooled by the cooling device 30 as shown in FIG. Is cut in the longitudinal direction, the mounting base 14 is bent together with the core material 12 into a substantially U-shaped cross section, and thereafter, finishing such as surface treatment is performed, whereby the weather strip is manufactured.
[0030]
【The invention's effect】
According to the present invention described above, since the contact area between the rubber and the transfer roller that supports the lower surface of the core material embedded portion in the foamed rubber portion is reduced, stretching of the rubber layer by the transfer roller is reduced. The occurrence of an undesired bulge shape is suppressed, and a regular-shaped weather strip can be obtained. In addition, since the non-foamed solid rubber portion in which the core material is conventionally embedded can be changed to the foamed rubber portion, the weight of the weather strip can be reduced.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view in a manufacturing process according to an embodiment of the present invention, and FIG. 1B is a perspective view of a transport roller in the embodiment.
FIG. 2A is a cross-sectional view in a manufacturing process according to another embodiment, and FIG. 2B is a perspective view of a transport roller in the embodiment.
FIG. 3A is a cross-sectional view in a manufacturing process according to still another embodiment, and FIG. 3B is a perspective view of a transport roller in the embodiment.
FIG. 4A is a cross-sectional view in a manufacturing process according to still another embodiment, and FIG. 4B is a perspective view of a transport roller in the embodiment.
FIG. 5 is a sectional view of a weather strip for an automobile.
FIG. 6 is a perspective view of a rear portion of the automobile.
FIG. 7 is a schematic view of a weather strip manufacturing process.
FIG. 8 is a diagram showing an extruded cross-sectional shape of a weather strip.
FIG. 9 is a cross-sectional view of a conventional weatherstrip manufacturing process.
FIG. 10 is a cross-sectional view of a conventional weatherstrip in which a bulge shape has occurred.
FIG. 11 is a perspective sectional view of a conventional weatherstrip in which a bulge shape has occurred.
FIG. 12 is a partially cutaway perspective view in a conventional weather strip manufacturing process.
[Explanation of symbols]
12 Core material 14 Mounting base 16 Hollow seal portion 20 Holding lip 22 Extruders 24a-d Transport rollers 26 Heating device 42 Central support portions 48, 52 Projection Part 54 ... Projection

Claims (5)

A method of manufacturing a weatherstrip including a foamed rubber portion and a core material embedded in the foamed rubber portion,
A step of continuously extruding the rubber material to be the foamed rubber portion together with the core material in a predetermined cross-sectional shape by using an extruder, and a plurality of transport rollers arranged at intervals in the extrusion direction with the extruded continuous body And vulcanizing by running through the heating device while supporting the lower surface with,
The transport roller includes a support portion that supports the lower surface of the core material via a rubber layer having a required thickness, and the support portion abuts and supports the lower surface flat portion of the rubber layer in a planar, linear, or dot shape. A method of manufacturing a weather strip, comprising a plurality of convex portions, wherein the plurality of convex portions support the lower surface of a core material embedded portion and transport the continuous body. The weatherstrip includes a mounting base having a substantially U-shaped cross section and a flange holding lip inside thereof, and a sealing portion made of sponge rubber protruding from the mounting base, wherein the mounting base is formed of the sponge. The foamed rubber portion made of foamed rubber having a larger specific gravity than rubber, wherein the core material is embedded in a substantially U-shaped cross section,
The mounting base is extruded from the extruder in a flat state, and the central part of the lower surface of the extruded mounting base is run in a heating device while being supported by the support part of the transport roller. The method for manufacturing a weather strip according to claim 1, wherein the weather strip is bent in a U-shaped cross section together with the core material. The method for manufacturing a weather strip according to claim 1, wherein the support portion of the transport roller comprises an annular convex portion divided into a plurality of portions in a width direction by a circumferential groove. The method for manufacturing a weather strip according to claim 1, wherein the support portion of the transport roller has a gear shape divided into a plurality of portions in a circumferential direction by a width direction groove. The method according to claim 1, wherein the support portion of the transport roller includes a plurality of protrusions arranged at predetermined intervals in a circumferential direction and a width direction.

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