JP2000135581A - Hollow extrusion molding product and forming method of gas ventilation hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas ventilating method for making an appearance of a gas ventilation hole of a weather strip good, and setting the hole making portion and direction freely. SOLUTION: Gas ventilation holes 13a and 13b of a weather strip 1 are formed to even a soft-conditioned molding product 1 immediately after extrusion under a non-contact condition by laser heating, without causing deformation and with a good appearance. By varying a laser radiation focus point, the gas ventilation hole 13b is formed in a manner to penetrate through a dividing wall 9 of plural hollow parts 5a and 7a, and the gas pressure of the hollow parts 5a and 7a is balanced for maintaining a good product shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded product such as an automobile weather strip having a hollow portion and a method for forming a vent hole therefor.

[0002]

BACKGROUND OF THE INVENTION Weather strips for automobiles are generally
It has a mounting portion attached to the periphery of the door opening or the periphery of the door, and a hollow seal portion integrated with the mounting portion and capable of elastically contacting the door or the door opening. This weather strip is formed by extruding a rubber or resin material into a belt shape using an extruder, and then joining the terminals together to form a ring or closing the terminals.

An extruded product such as a weather strip having a hollow portion needs to maintain the shape of the hollow portion by balancing the hollow portion with the atmosphere. When extruded with mixed vulcanized rubber, when heated and vulcanized after extrusion, the decomposed gas of the foaming agent is filled in the hollow part, and the gas pressure of the decomposed gas expands the hollow part excessively Such a phenomenon occurs.

Therefore, conventionally, in the case of an extruded product having a hollow portion, gas generated in the hollow portion is discharged to the outside through a degassing passage formed in a die of the extruder, and the extruded product is refilled. A gas vent hole penetrating from the outer wall to the hollow portion is formed to balance the pressure between the hollow portion and the atmosphere.

[0005] Conventionally, a method of forming a gas vent hole in a hollow extruded product is performed by drilling the outer wall of a molded product extruded from an extruder by rotary cutting using a drill or a drill.
Alternatively, the contact is performed by a mechanical method such as piercing by piercing a syringe needle.

[0006]

However, when the above-mentioned conventional contact method using mechanical means is employed, there are the following problems.

(1) Problems caused by contact In the case of a contact method using mechanical means, drilling cannot be performed unless the material is brought into contact with an extruded product (work). Therefore, problems caused by contact, for example, breakage of the formed product and burrs are caused. I couldn't avoid it.

(2) Followability Since the extruded product is successively sent out at a predetermined speed from the extruder, when the contact hole is punched by a mechanical means on this production line, the mechanical means is used for the extruded product. However, in the case of high-speed extrusion, there is a drawback that it cannot follow the extrusion speed.

(3) Restriction of perforation site and direction When a gas vent hole is perforated in a molded product immediately after being discharged from an extrusion die of an extruder, the molded product is deformed due to mechanical contact with a soft molded product. As a result, there are restrictions on the perforation site and the perforation direction.

(4) It is difficult to perforate an extruded product having a plurality of hollow portions. When a plurality of hollow portions are formed in the extruded product, the extruded product is brought into contact with a soft product by a contact method using mechanical means. It was difficult to pierce two or more hollows.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the problem of perforation by mechanical means in the method of forming a vent hole of an extruded product having a hollow portion, and as a result, the laser heating method It has been found that the adoption of the non-contact piercing method can prevent deformation of the extruded product even if it is a soft extruded product immediately after extrusion.

In general, a gas venting passage is formed in a die of an extruder and communicates from the hollow portion of the extruded product to the outside. Gas generated in the hollow portion is discharged to the outside through the gas venting passage. However, if the non-contact perforation method by laser heating is adopted, the following operation and effect can be exhibited.

That is, if a gas vent hole penetrating the hollow portion of the extruded product is pierced by irradiating a laser beam from the outer wall of the extruded product, the hole is formed in a non-contact state.
There is no deformation of the work, no breakage or scorching (burr) of the hole, and the appearance of the gas vent hole is improved. Also,
With laser heating, it was possible to pierce instantaneously, and even in the case of high-speed extrusion molding, a gas vent hole could be formed sufficiently in response to this.

Further, since the drilling is performed in a non-contact state,
Even in the soft state immediately after extrusion, there is no restriction on the perforated portion and perforated direction, and the perforated portion can be freely selected. Furthermore, because of laser heating, the appearance of the hole can be freely changed.For example, a hole diameter, particularly a small-diameter gas vent hole can be formed with good appearance, and the laser irradiation time can be reduced while the laser oscillator is fixed. If it is set to be long, it is possible to form a long hole along the extrusion direction of the molded product to be extruded and moved.

In addition, in an extruded product having a plurality of hollow portions, a gas vent hole formed in the outer wall of the molded product and a gas vent hole penetrating a partition partitioning between the hollow portions can be formed at one time. In addition, the hole forming operation can be simplified. Here, the present invention is applicable to an extruded product having three hollow portions, regardless of the number of the plurality of hollow portions as long as the number is two or more.

If there is a difference between the plurality of hollow portions, a gas vent hole can be formed in the partition between the hollow portions to balance the generated gas pressure between the two hollow portions.
That is, when there is a difference in the size of the plurality of hollow portions partitioned by the partition wall, when the amount of foaming decomposition gas generated per unit length in the circumferential length of the hollow portion cross section is constant, the per unit cross sectional area of the hollow portion is obtained. Since the gas amount is larger in the small hollow portion than in the large hollow portion, the gas pressure in the small hollow portion becomes large according to Boyle's law, and the degree of deformation of the small hollow portion becomes larger than that in the large hollow portion. . Therefore, if a gas vent hole is formed in the partition wall between the large and small hollow parts, it is possible to balance the pressure of the generated gas between them, and discharge the generated gas from the gas vent hole formed on the outer wall of the molded product. Since the pressure can be balanced between the hollow portion and the atmosphere, the outer shape of the molded article surrounding the hollow portion can be maintained in a desired shape.

In particular, by changing the laser irradiation focus,
The gas vent hole on the outer wall side of the molded product can be made smaller and the gas vent hole formed in the partition wall on the back side can be made larger (including the long hole), so that the gas generated from the large and small hollow portions can be distributed. It can be done smoothly. Such an approach,
In the case of an extruded product having a small hollow portion where the gas vent hole is not large because the amount of generated gas per cross-sectional area is large but the opening margin is small, it is particularly effective in guiding the generated gas to the large hollow portion side .

The laser heating is performed using a laser oscillator arranged on an extrusion molding line. Examples of the laser medium include a gas medium such as CO ₂ gas or a solid medium such as YAG (yttrium aluminum garnet). Further, the focus change of the laser beam can be freely set by, for example, a well-known electromagnetic focusing lens, a deflection lens, and an auto-focus function provided in the laser oscillator, and accordingly, the laser focal length and the focus position are appropriately set. Can be set.

If the above laser oscillator is used,
Even when the extruded product is extruded at high speed, the laser irradiation position can be gradually changed in accordance with the extruding movement speed of the work through the deflection lens, and the extruded product can be perforated at the same position. As a method of perforating the same part of the molded product, a method of causing the laser oscillator itself to follow the extrusion direction can be adopted.

The formation of the gas vent hole as described above can be applied irrespective of whether it is a foamed extruded product or not. However, an extruded product containing a foaming agent that easily generates a foam decomposition gas (extruded by water foaming). It is particularly effective to apply the method to molded articles. Further, the material of the extruded product is applicable regardless of rubber or thermoplastic resin (including elastomer).

Further, the formation time of the gas vent hole is as follows.
It goes without saying that it may be carried out not only in the soft state immediately after extrusion but also after curing. For example, when performed in a soft state immediately after extrusion, if the molded article is a rubber material, it may be performed before vulcanization, if the molded article is a resin material, it may be performed before cooling, and if formed after curing, when the molded article is a rubber material May be performed after passing through a vulcanization tank, or in the case of a thermoplastic resin, after passing through a cooling tank. In particular, in the case of a rubber extruded product in which a large amount of foaming gas is easily generated by heat vulcanization, it is particularly effective to form a gas vent hole in a soft state immediately after extrusion of unvulcanized rubber.

The object for forming the gas vent hole is not limited as long as it is a hollow extruded product, but it is particularly suitable to be applied to weather strips for automobiles, opening trims, and various moldings. It is most suitable when applied to a weather strip for automobiles having a hollow seal portion that requires high performance. Further, the extruded product having two or more hollow portions includes a hollow mounting portion mounted on a peripheral edge of a door opening or a door peripheral edge, and a hollow sealing portion integrated with the mounting portion. An example is an automobile weather strip.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of an automobile using a weather strip which is an extruded product according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a schematic diagram showing an extrusion molding line, and FIG. Perspective view showing a die part of the machine,
FIG. 5 is a view showing a gas vent path of the die, and FIG. 6 is a sectional view of the weather strip.

As shown in FIG. 1, a weather strip 1 for an automobile is attached to a periphery of a door 3 of an automobile 2 and is fitted to a retainer 4 having a U-shaped cross section formed on the periphery of the door as shown in FIG. A hollow mounting portion 5, a hollow sealing portion 7 integrated with the mounting portion 5 and elastically contacting the peripheral edge 6 of the door opening, A seal lip 8 that can be brought into contact with the hollow portion 5a of the mounting portion 5 and a hollow portion 7a of the seal portion 7;
Is divided by

As shown in FIG. 3, such a weather strip 1 is extruded from an opening 12 of a die 11 of an extruder 10 using a rubber or the like mixed with a foaming agent as a raw material, It is vulcanized in a vulcanizing tank 18 and formed into a predetermined shape.

In the step of forming the extruded product 1,
The gas generated in the hollow portions 5a and 7a is discharged to the outside through degassing passages 22 and 23 formed in the die 11 as shown in FIG. It is discharged through a gas vent hole 13a formed by laser irradiation of a laser oscillator 15 disposed between the vulcanizing tank 18 (oven) and the vulcanizing tank 18 (oven).

As shown in FIG. 5, the gas vent passage 22 of the die 11 has a die 1 opened to form a hollow portion on the seal portion side.
The extruder 10 includes two through holes 24 and 25 formed inside and outside the one ring-shaped opening 12, and a passage 26 connecting the two through holes 24 in the cylinder of the extruder 10. Since the gas vent path 23 on the side of the mounting portion 5 has the same configuration, it is indicated by the same reference numeral in FIG. 5 and the description thereof is omitted.

In order to maintain the shape of the hollow portions 5a and 7a and balance with the atmospheric pressure, the laser irradiation 15a utilizes the straightness of the laser irradiation 15a to cause the outer wall of the mounting portion 5 to be thermally decomposed and penetrated, and the gas vent hole is provided. 13a, the partition 9 between the hollow portions 5a and 7a is also thermally decomposed through the hollow portion 5a to remove the gas vent hole 1a.
3b is formed through.

The laser oscillator 15 uses, for example, CO ₂ gas as a laser medium, and further has an electromagnetic focusing lens (not shown) and an automatic focusing function in addition to the well-known deflection lens 19. . By these means, the laser focal length and the focal position can also be set appropriately, and the laser beam 15a is applied to the same part of the molded product by following the extrusion speed of the extruded product 1 such as a weather strip, and the gas vent hole 1 is formed.
3a and 13b can be formed, and it is possible to sufficiently cope with high-speed extrusion.

FIG. 7 shows a gas vent hole 13b formed in the partition wall 9.
An example in which the hole diameter is formed larger (longer) than the gas vent hole 13a in the outer wall of the mounting portion 5 is shown. The formation of such holes
As shown in FIGS. 8A and 8B, the focal point 1 of the laser beam 15a
It can be formed by changing 5b.
FIG. 8A shows that the focal point 15b of the laser beam 15a is
3B shows an example in which the focal point 15b is changed to the inside of the hollow portion 5a of the mounting portion 5, and FIG. In any case, the gas vent hole 13a on the outer wall side of the mounting portion 5 can be formed with a small diameter, and the gas vent hole 13b of the partition 9 with the seal portion 7 can be formed with a large diameter.

As described above, if the gas vent hole 13a in the outer wall of the mounting portion 5 is formed small, not only the appearance is improved, but also the hollow portion 5a of the mounting portion 5 is small, and the per unit area thereof is reduced. In the case where the gas vent hole 13a cannot be enlarged because the amount of gas is large and the hole allowance cannot be taken, the gas generated in the hollow portion 5a on the mounting portion side is smoothly guided to the large hollow portion 7a on the seal portion side. This is a particularly effective method, and the pressure balance between the two hollow portions 5a and 7a can be maintained, so that the appearance of the mounting portion 5 and the seal portion 7 can be maintained in a desired shape.

In the above embodiment, the outer wall of the mounting portion 5 and the hollow portions 5a, 7a are utilized by utilizing the straightness of laser irradiation.
Although the example in which the gas vent holes 13a and 13b are formed in the partition wall 9 described above is shown, the present invention is not limited to this, and the number of gas vent holes perforated is not limited as long as it is one or more. The location and direction of the perforation can also be freely set.

FIG. 9 shows an example of a perforated portion and a perforated direction of a vent hole of a weather strip 1 which is an extruded product.
As shown in the drawing, for example, when the gas vent hole is formed in the mounting portion 5, even when the gas vent hole is formed from the side of the retainer (indicated by 13a in the figure), it is on the side of the seal lip 8 (indicated by 13c in the figure). Is also good. Further, even when formed on the outer wall of the hollow seal portion 7 (indicated by 13d in the figure), the formation position can be set freely.

[0034]

As is apparent from the above description, according to the present invention, since the gas vent hole of the extruded product is formed in a non-contact state by laser heating, there is no deformation of the work and good appearance. Not only is it possible to form holes, but also because gas vent holes can be formed by penetrating the partitions of multiple hollows, the effect of maintaining a good product shape by balancing the gas pressures of multiple hollows can be achieved. is there.

[Brief description of the drawings]

FIG. 1 is a side view of an automobile using a weather strip which is an extruded product according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a schematic diagram showing an extrusion molding line.

FIG. 4 is a perspective view showing a die portion of the extruder.

FIG. 5 is a view showing a gas vent path of a die.

FIG. 6 is a sectional view of a weather strip.

FIG. 7 is larger (longer) than the outer wall of the weatherstrip
Sectional view showing an example of providing a hole in a partition

FIGS. 8A and 8B are diagrams showing an example of changing a laser focus; FIGS.

FIG. 9 is a cross-sectional view showing a position where gas vent holes are formed in the weather strip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Weather strip 2 Automobile 3 Door 4 Retainer 5 Mounting part 5a Hollow part 6 Door opening peripheral edge 7 Seal part 7a Hollow part 13a to 13d Gas vent hole 15 Laser oscillator 19 Deflection lens

Continued on front page F term (reference) 4E068 AA02 AF00 CA11 DA00 DB07 4F207 AA45 AG08 AH23 KA01 KA11 KA20 KL41 KL62 KL74 KL86 KW26 KW41

Claims (7)

[Claims] 1. A method for forming a gas vent hole in a hollow extruded product, wherein a gas vent hole penetrating from the outer wall to the hollow portion is formed by irradiating a laser beam in the extruded product having a hollow portion. 2. An extruded product in which two or more hollow portions are formed through a partition wall, and a laser beam is irradiated from the outer wall of the extruded product to form a gas vent hole by piercing the outer wall and the partition wall. A method for forming a vent hole in an extruded product. 3. The method according to claim 2, wherein the partition wall is formed so that the hole diameter of the partition wall is larger than the hole diameter formed in the side surface of the extrusion molded product. 4. The method according to claim 1, wherein the extruded product is a foamed extruded product of rubber or resin. 5. The method according to claim 1, wherein the extruded product is perforated in a soft state immediately after being extruded from an extruder. 6. The method according to claim 1, wherein said extruded product is a weather strip for automobiles. 7. A hollow extruded product having a vent hole formed by the method according to any one of claims 1 to 6.