JP2000246781A - Mouthpiece structure for composite extrusion-molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a thermal effect between a mouthpiece for rubber and a mouthpiece for resin without inserting a heat-insulating material. SOLUTION: A small diameter protruding section 13 is formed on the front surface of a mouthpiece 5 for rubber from the mouthpiece 5 for rubber extrusion and a mouthpiece 9 for resin extrusion, which are closely joined to each other, and the mouthpiece 5 for rubber is closely joined to the mouthpiece 9 for resin only by the area of the small diameter protruding section 13 which is a minimum necessity. By forming a temperature adjusting passage on the small diameter protruding section 13, and making a cooling medium flow through the temperature adjusting passage, the mouthpiece 5 for rubber is forcibly cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die structure for composite extrusion molding, and more particularly to a method for simultaneously extruding a long rubber molded product having a uniform cross-section such as a weather strip or a glass run for automobiles. The present invention relates to a die structure for simultaneous coextrusion molding of a so-called different material in which a part of the rubber molded product is covered with a resin material.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 5-31785 discloses a die structure for simultaneous coextrusion molding of different kinds of materials.
In addition to Japanese Patent Application Laid-Open No. Hei 5-138712 and Japanese Patent Application Laid-Open No. 5-138712, those described in Japanese Patent Application Laid-Open No. Hei 7-214636 are known.

In these conventional techniques, as is well known, a rubber die and a resin die are arranged close to each other, while a proper molding temperature of the rubber die and a proper temperature of the resin die are determined. Are different from each other, so that a heat insulating material is interposed between the two bases in order to cut off the thermal influence between the bases.

[0004]

In the prior art as described above, since the extrusion molding is a continuous molding method, the temperature at the rubber base and the temperature at the resin base higher than the rubber base are particularly high. If the difference from the temperature in step (a) is 100 ° C. or more, a sufficient heat insulating effect cannot be obtained unless the thickness of the heat insulating material is increased, which results in poor molding such as surface burning, which is not preferable. On the other hand, as the thickness of the heat insulating material increases, the material passage must be longer,
A large number of man-hours are required for adjusting the extrusion pressure and the extrusion speed. In addition, when a non-metallic material is used as the heat insulating material, the rigidity of the non-metallic material is inferior to the rigidity of the die, so that there is a disadvantage that the material easily leaks from the joint between the die and the heat insulating material. .

Further, Japanese Patent Application Laid-Open No. 5-13871 described above.
In Japanese Patent Application Publication No. 2 (1993) -207, together with the use of a heat insulating material, a heat insulating space into which a cooling medium such as cooling air or a cooling liquid is introduced is provided on the mating surface of the rubber die and the resin die to improve the heat insulating effect. However, since it is assumed that the heat insulating space communicates with the material passage, the rubber material tends to leak to the heat insulating space due to the variation of the rubber material, thereby blocking the heat insulating space. As a result, it becomes difficult to stably maintain the function of the heat insulating space for a long period of time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is intended to provide a base structure capable of obtaining a necessary and sufficient heat insulating effect without using a heat insulating material. is there.

[0007]

According to the present invention, a molded product having a predetermined cross-sectional shape is extruded with the rubber material at the tip of an extruder for extruding an unvulcanized rubber material. A rubber base having a material passage for molding is mounted, and a molten resin material is provided on the front side of the rubber base while having a predetermined resin passage and extruded from the rubber base. It is premised that the die has a die structure in which a resin die for extruding and molding at least a part of the molded product is brought into close contact with the resin die.

Then, a small-diameter projection protruding toward the resin base to extend a material passage substantially at the center of a surface of the base body forming the rubber base in contact with the resin base. Forming a portion, the tip surface of the small-diameter protrusion is brought into close contact with a resin die having a larger diameter, and the small-diameter protrusion has a predetermined temperature adjusting medium that is not in communication with a material passage. It is characterized in that a temperature-adjusting passage for flowing is formed.

In this case, the temperature and the flow rate of the temperature adjusting medium itself are appropriately adjusted as needed.

[0010] Therefore, in the present invention, the rubber die is formed by making the end on the resin die side of the rubber die a small-diameter projection to substantially minimize the contact area with the resin die. The heat transfer between the resin base and the resin base is minimized. In addition, the outer peripheral surface of the small-diameter projection itself is directly exposed to the outside air, and a temperature adjusting medium such as cooling water or cooling oil flows through a temperature control passage formed in the small-diameter projection. Due to the temperature adjusting effect, the thermal influence between the rubber base and the resin base is suppressed, and as a result, a necessary and sufficient heat insulating effect can be obtained.

[0011]

According to the present invention, a necessary and sufficient heat insulating effect can be obtained by a combination of the small-diameter protrusion formed on the rubber base and the use of the temperature adjusting medium. It is not necessary to make the material passage unnecessarily long, and there is no need for a large number of man-hours to adjust the extrusion pressure, etc., and workability is also prevented while preventing molding defects such as so-called surface burning. In addition to this, there is no fear of material leakage or the like because no heat insulating material of a different material is interposed between the bases. This also improves the molding quality.

Further, since the temperature control passage through which the temperature control medium flows is completely independent without communicating with the material passage, there is no risk of clogging or the like unlike the conventional case. There is an effect that the original temperature control effect or heat insulation effect can be maintained for a long time.

[0013]

1 and 2 show a preferred embodiment of the present invention. A die for extruding a long weather strip (glass run) 50 having a uniform cross section as shown in FIG. 2 shows an example of the structure. The weather strip 50 is provided with lips 52 and 53 at both ends of a main body portion 51 made of, for example, solid rubber, which are in sliding contact with the window glass. Polypropylene, TP
Resin coating layer 5 made of thermoplastic resin such as O and TPS resin
4 are formed.

As shown in FIGS. 1 and 2, a screw 3 is inserted into a head 2 of an extruder 1 for extruding a rubber material, and the unvulcanized rubber material is sequentially extruded by the rotation of the screw 3. It is supposed to be. A rubber base 5 having a material passage 4 formed in the center is fixed to a front surface of the head 2 with bolts 6. Further, a back plate 7 and a face plate are provided on the front surface of the rubber base 5. The resin bases 9 comprising the resin bases 8 are also fixed by bolts 10 and collars 11 so as to overlap each other.

The rubber base 5 is formed around a base plate 12 serving as a base of the base, and a small-diameter projection 13 is integrally formed at the center of the front surface of the base plate 12 toward the resin base 9. Have been. Thus, the rubber base 5 is in close contact with the resin base 9 with only the minimum necessary front surface of the small-diameter projection 13. A material passage 4 made of a rubber material is formed so as to penetrate the base plate 12 and the small-diameter projection 13 mutually, and the material passage 4 has a tapered shape toward the resin base 9. Finally, at the exit side of the small-diameter projection 13, it converges with the opening 4 a having the same cross-sectional shape as the weather strip 50 to be formed.

A temperature control passage 14 is formed in the small-diameter projection 13 so as to surround the material passage 4.
Hose 15 and 16 for supplying a temperature adjusting medium are connected to both ends of the temperature adjusting passage 14. A cooling medium such as cooling water or cooling oil whose temperature is controlled is supplied to the temperature control passage 14 via the hoses 15 and 16 so as to constantly flow and circulate. The temperature is controlled so that the small-diameter projection 13 has an appropriate temperature.

On the other hand, the back plate 7 and the face plate 8 for forming the resin base 9 are formed with flow holes 17 and 18 having the same shape as the sectional shape of the weather strip 50 to be formed. Both circulation holes 1
The plates 7 and 18 communicate with each other by pressing the plates 7 and 8 together. A resin introduction groove 19 is formed on the surface of the back plate 7 which is in contact with the face plate 8 so as to communicate with the flow holes 17 and 18. The resin introduction groove 19 is formed on a side surface of the back plate 7. And open to the outside of the back plate 7,
An extruder 21 for extruding a resin material is connected to the resin introduction hole 20. The face plate 8 includes a heater 22.
Is provided, and the heating of the face plate 8 is controlled by the heater 22 so that the temperature of the face plate 8 becomes a predetermined temperature.

Therefore, according to the die structure for composite extrusion molding thus constituted, the unvulcanized rubber material is extruded from the extruder 1 and the resin introduction holes 20 and the resin introduction holes are introduced from the other extruder 21. When the resin material is supplied through the groove 19, the rubber material passes through the material passage 4 of the rubber base 5, whereby an intermediate molded product having the same cross-sectional shape as shown in FIG. 3 is continuously extruded. The intermediate molded product is directly introduced into the flow holes 17 and 18 of the resin base 9.

Since the above-described resin introduction groove 19 only opens at a portion corresponding to one lip 53 (see FIG. 3), an intermediate molded product made of only a rubber material as described above. In the process of passing through the flow holes 17 and 18 of the resin base 9, the resin material is continuously extruded only to the portion corresponding to the lip 53, and only that portion is covered with the resin material, and the resin coating shown in FIG. Layer 54 is formed.

In such a molding process, the rubber base 5 rises to, for example, about 70 to 100 ° C. due to the heat of the rubber material itself, while the resin base 9 similarly receives the heat of the molten resin material, for example. The temperature rises to about 160 to 220 ° C. Therefore, when the forced cooling is not performed, the temperature of the resin base 9 is transmitted to the rubber base 5 through the contact portion between the small-diameter projection 13 and the back plate 7 and the rubber base is equilibrated with each other. When the temperature of the rubber material 5 is increased and the rubber material passes through the material passage 4, the vulcanization partially progresses or the surface is easily burnt.

However, in this embodiment, the rubber base 5 is used.
The heat transfer from the resin base 9 to the rubber base 5 side is suppressed by making the contact area between the resin base 9 and the resin base 9 only the required minimum end surface of the small-diameter protrusion 13, and the small-diameter protrusion is provided. Since the outer peripheral surface of the portion 13 is exposed to the outside air, the cooling efficiency by cooling is promoted by this. As well,
Since a cooling medium such as cooling water or cooling oil flows through the temperature control passage 14 of the small-diameter projection 13, the small-diameter projection 13 or the entire rubber base 5 is forcibly cooled.
As a result, an excessive temperature rise of the rubber base 5 is suppressed by a synergistic effect of the above-described respective cooling actions, and in particular, occurrence of molding defects such as surface burning and early vulcanization, which are fatal defects of the weather strip 50, are suppressed. It can be prevented beforehand.

Further, since no heat insulating material as in the prior art is required at all, the rubber passage 4 does not become unnecessarily long, and also the rubber cap 5 and the resin cap 9, especially the head 2. Since metal plates having high rigidity are mutually pressed together, there is no danger of material leakage from the joint surfaces of the plates unlike the case where a non-metallic heat insulating material is interposed.

Here, in the present embodiment, an example in which the resin coating layer 54 is formed on only one lip 53 has been described. However, when the resin coating layer 54 is formed on both lips 52 and 53 at the same time, it is needless to say. The same applies to the case where the resin coating layer 54 is formed in another portion.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a base showing a preferred embodiment of the present invention.

FIG. 2 is an explanatory vertical sectional view of FIG. 1;

FIG. 3 is a sectional view showing an example of an automobile weather strip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Extruder for rubber materials 4 ... Material passage 5 ... Rubber base 7 ... Back plate 8 ... Face plate 9 ... Resin base 12 ... Base plate 13 ... Small diameter protrusion 14 ... Temperature control passage 17, 18 ... Distribution hole 21 ... Extruder for resin material extrusion 50 ... Weather strip

Claims (1)

[Claims] An extruder for extruding an unvulcanized rubber material is provided with a rubber base having a material passage for extruding a molded product having a predetermined cross-sectional shape with the rubber material. On the front side of the base, a molten resin material is extruded onto the surface of a molded product extruded from the rubber die while having a predetermined resin passage, and a resin die covering at least a part of the molded product is overlapped. A small diameter projecting toward the resin base to extend a material passage substantially at the center of a surface of the base body forming the rubber base in contact with the resin base. A protrusion is formed, and the tip end surface of the small-diameter protrusion is brought into close contact with a resin die having a larger diameter than the small-diameter protrusion, and the small-diameter protrusion is not communicated with a material passage and has a predetermined temperature adjusting medium. Through A die structure for composite extrusion molding, characterized in that a flowing temperature control passage is formed.