JPH0242346B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a weather strip that is attached along an opening in an automobile body or around an opening/closing member such as a door or trunk lid that opens and closes the opening.

[Prior art] This type of weather strip has a solid rubber base with a U-shaped cross section and a sheet metal core embedded,
Weatherstrips with a sponge rubber seal projecting from the base are commonly used. In order to improve the flexibility of the weatherstrip, the core material is often buried in a plurality of core material pieces.

Generally speaking, the manufacturing method for this weather strip is to integrally extrude a long flat core material, solid rubber and sponge rubber, to form an extruded molded product in which the core material is covered with the solid rubber, and the sealing portion of the sponge rubber protrudes from the solid rubber. After obtaining and vulcanizing the rubber, repeated bending stress is applied to the solid rubber part containing the core material to divide the core material into predetermined lengths.
Furthermore, a method has been adopted in which the solid rubber portion is bent into a U-shaped cross section.

By the way, there are various types of sponge rubber seals.

In the form shown in Fig. 7, the weather strip 1'
The seal portion 12a is hollow, and its base is located at the bent portion of the base portion 11 having a U-shaped cross section. 12b is an auxiliary seal part, 13 is a retaining lip that holds the flange of the body, and 14' is a core material. Although the conventional core material is made of metal, the core material of the weather strip of the present invention is made of synthetic resin. In this type of weather strip 1', when the solid rubber base 11 including the core material 14' is bent into a U-shape after vulcanization, the base of the sealing portion 12 may tear, so prepare the core material 14' in advance. A manufacturing method that involves molding is used.

FIG. 6 shows a process diagram of conventional manufacturing.
4' is sent to a bending machine 20, where it is preformed into a substantially U-shaped cross section with a shallow bending angle, as shown in FIG. 7B.

Next, the extruder 3 integrally extrudes the core material 14' and the rubber material into the shape shown in FIG. 7C. Next, the core material 14' is heated with the high frequency induction heating device 4,
The rubber is heated with a high frequency dielectric heating device 5, and then heated in a hot air tank 6.
It is vulcanized by passing it through. The reason why the core material 14' is heated by high frequency induction heating is that even if rubber is heated by high frequency dielectric heating, the metal core material will not be heated, and the rubber around the core material will absorb heat and will not be vulcanized. .

Next, the extrusion molded body is crushed into a flat plate shape as shown in FIG. A vertical bending stress is repeatedly applied to the surface of the core material 14'. As the core material 14', for example, as shown in the core material 14 in FIG. Slots 141 are formed at predetermined intervals, and score lines 142 are formed from both ends of every other slot 141 to the side edges of the sheet metal, so that bending stress is applied to the core material. Stress is concentrated at a location 142 and the wire is broken there.

Next, a U-shaped bending process is performed using a U-shaped bending machine 10 to obtain a weather strip as shown in FIG. 7D, and the weather strip is cut into a predetermined length using a cutting machine 100.

Another type of weather strip has a shape shown in FIG. 2 (however, the conventional weather strip uses a metal core material as the core material), and has an auxiliary seal portion 12b rising up. In this case, if a flat core material is used, the auxiliary seal part 12b protruding from the flat solid rubber part will come into contact with the hollow seal part 12a during extrusion molding. Similar to the manufacturing method, a core material preforming process is included.

[Problems to be solved by the present invention] As described above, weather strips are manufactured through a large number of steps, and a large load must be applied to bend the core material, and furthermore, there is a risk of breakage of the core material. Since bending stress must be applied repeatedly, there is a strong desire to simplify the process and facilitate processing of the core material.

The present invention aims to meet this demand.

[Means for Solving the Problems] First, in the present invention, a core material of thermoplastic synthetic resin such as vinyl chloride resin or ABS resin is used as the core material.

In the preforming process, the core material is preheated and softened, and then bent into a shape close to a U-shape.

After extrusion molding and vulcanization, the core material is slowly cooled until it reaches a semi-hardened state, and after the core material is divided, it is immediately subjected to U-shaped bending. Then cool and cut.

In the present invention, in the vulcanization process, it is possible to use a conventional means of raising the temperature of the extruded body from the outside using a heating medium such as glass beads, but it is more efficient to use high-frequency induction heating. .
In this case, there is no need to use high-frequency dielectric heating in conjunction with a weather strip embedded in a metal core. In other words, with metal core materials, the temperature of the core material is first raised by high-frequency induction heating, and then the temperature of the rubber is raised with high-frequency dielectric heating, but with synthetic resin core materials, the core material is heated together with the rubber using only high-frequency dielectric heating. Since the temperature can be raised, the rubber material can be sufficiently vulcanized to its center.

In addition, in the vulcanization process, the softened synthetic resin core material cannot be pulled out from the end of the process. Therefore, it is necessary to provide a conveying means such as a belt conveyor in part or all of the vulcanization process to reduce the tension applied to the extruded product as much as possible.

[Operations and Effects] Since a thermoplastic synthetic resin core material is used, the core material can be easily bent by heating it in the core material preforming step.

After vulcanization, the core material is broken and U-shaped in the semi-hardened state at the same time, so the process can be simplified. Moreover, the core material can be broken without crushing the extruded product into a flat plate, and U-shaped bending can be performed with a smaller load than in the case of a metal core material.

The resulting weatherstrip is lighter than one in which a metal core is embedded, and there is no risk of rust forming on the core even if the core is exposed at some point.

[Example] Examples of the present invention will be described below, focusing on the differences from the conventional example described above.

4 and 5 show the steps of the manufacturing method of the present invention for obtaining the weather strip 1 shown in FIG. 1. FIG.

First, the ABS resin core material 14 having the structure shown in FIGS. 3 and 5A is sent out from the cart 2. This core material 14 is preheated to about 160°C in a preheating tank 20A, and then bent in a bending machine 20B into a shape with a smaller bending angle than a U-shape and a V-shape on the upper side, as shown in FIG. 5B. do. The core material 14 can be easily bent with a smaller load than a metal core material.

Next, the extruder 3 integrally extrudes the core material 14, solid rubber, and sponge rubber. As shown in FIG. 5C, the extrusion molded product has a core material 14 wrapped in solid rubber, a retaining lip 13 protruding from the inner surface of the solid rubber, and both sealing parts 12a and 12b made of sponge rubber protruding from the outer surface.

Next, the extruded body is sent to a vulcanization process. That is, the high frequency dielectric heating device 5 heats the rubber and core material 14 to
The temperature is raised to 150℃, and the hot air tank 6 is heated to 200 to 220℃.
It is vulcanized by passing through it and keeping it warm.

Next, the core material 14 is slowly cooled to about 100°C in a slow cooling tank 90 to a semi-hardened state, and in this state, the core material 14 is cut into the core material by a core material separator 9 consisting of a large diameter roll and a small diameter roll. The product is broken by cutting along the line 142 (Fig. 3), immediately bent into a U-shape by the bending machine 10, and stabilized in shape by cooling with the cold air blower 10B, as shown in Fig. 5D. get. In this case, the semi-hardened core material 14 can be easily broken and bent. Subsequently, it is cut into a predetermined length using a cutting machine 100.

The weather strip shown in FIG. 2 also uses a core material 14 made of synthetic resin as a core material, and is manufactured by the same process as above, so a description thereof will be omitted.

As explained above, in the manufacturing method of the present invention, in the core material breaking and U-shaped bending process, the synthetic resin core material in a semi-cured state can be easily broken without being crushed into a flat plate as in the conventional method. , and can be bent into a U shape. Moreover, preforming of the core material can be easily performed with a much smaller load than that of a metal core material.
Moreover, the product obtained according to the present invention is lighter than one in which a metal core is embedded, and there is no fear of corrosion of the core. In this way, the present invention contributes to facilitating the manufacture of weatherstrips, reducing manufacturing costs, and improving the quality of the product.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are respectively sectional views of a weather strip obtained by the manufacturing method of the present invention;
FIG. 3A is a plan view of the core material, FIG. 3B is a side view of the core material, and FIG. 4 is a diagram showing the steps of the manufacturing method of the present invention.
Figure 5 A, B, C, and D are A-A in Figure 4, respectively.
6 is a diagram showing the steps of the conventional manufacturing method. A- in Figure 6
It is a sectional view along the A line, the BB line, the CC line, the DD line, and the EE line. 1... Weather strip, 11... Base, 12
a, 12b... Seal part, 14... Synthetic resin core material, 20A... Preheating tank, 20B, 10... Bending machine, 3... Extruder, 4... High frequency induction heating device,
5... High frequency dielectric heating device, 6... Hot air tank, 90
... slow cooling tank, 9 ... core material separator, 10 ... U-shaped bending machine, 10B ... cold air feeder, 100 ... cutting machine.

Claims (1)

[Claims] 1. A method for producing a weather strip for an automobile, which has a base having a U-shaped cross section, a seal portion protruding from the base, and a number of divided core materials embedded in the base, the weather strip being made of thermoplastic synthetic resin and having a predetermined shape in the longitudinal direction. The process of feeding a long flat core material with stress concentration areas formed at intervals of a step of integrally extruding the preformed core material and rubber to obtain an extruded body in which the core material is covered with rubber and a seal portion protrudes; and a step of heating and retaining the extruded body. a step of slowly cooling the vulcanized extrusion molded body until the core material reaches a semi-hardened state, and a step of applying stress to the extrusion molded body with the core material in a semi-hardened state to change the core material to its original state. A process of dividing the core material at the stress concentration area, a process of bending the core material in a semi-hardened state into a U-shaped cross section together with the rubber containing it, and cooling the obtained weather strip. A method for manufacturing a weather strip for an automobile, which comprises the steps of stabilizing the cross-sectional shape and cutting the cooled weather strip to a predetermined length.