JP2003320593A - Method for annealing resin product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly remove a distortion occurring at a heat-welded portion of a resin product without requiring large facilities. <P>SOLUTION: In a method for annealing the resin product, a distortion of the resin product occurring at the heat-welded portion 4 welded by heating welding, such as hot plate welding, vibration welding, is removed by heating the heat-welded portion 4 by means of a heater 5. The method is provided with a process for raising the temperature of the surface 4a of the heat-welded portion up to target temperature by irradiation with far infrared rays, and a process for holding the surface temperature of the heat-welded portion at the target temperature by controlling the heating efficiency of the heater. During the holding process, the temperature of the inside 4b of the heat-welded portion is raised up to the target temperature or the temperature near the target temperature. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel method for annealing a resin product. More specifically, the present invention relates to a technique for removing a strain generated in a heat-welded portion of a resin product in a short time.

[0002]

2. Description of the Related Art Since stress is generated in a heat-welded portion of a synthetic resin part which is welded by a welding means such as a hot plate welding method or a vibration welding method, the above residual stress can be maintained by keeping the temperature constant for a certain time or longer. Need to be removed.

Therefore, in the prior art, a technique for removing residual stress by heating a resin product in a substantially hermetically-annealed furnace while it is conveyed on a predetermined path and maintaining the temperature at a constant temperature for a predetermined time or longer. There is.

For example, a traveling route for moving the resin product along a predetermined route is provided in the annealing furnace, and a heater is disposed in the vicinity of the traveling route so that the resin product travels along the traveling route from the start end to the end. There is a heater which is heated by the heater to be heated to a predetermined temperature and is kept at the predetermined temperature after reaching the predetermined temperature.

[0005]

The conventional annealing method described above has some problems.

First, since the temperature of the entire annealing furnace is raised by using a near-infrared heater as a heater, it takes time to raise the temperature of the resin product to a certain temperature. There is a problem that it is not consistent with the time required in the process. For example, in the case of a certain type of automotive lamp, the time required for each of the other steps is about 40 seconds, whereas the time required for the annealing step is about 15 minutes. Therefore, in order to prevent product stagnation on the production line, an annealing furnace capable of running 20 or more resin products is prepared on the line so that idle time does not occur in each process. I have to Therefore, there is a problem that a large space for an annealing furnace capable of running a large number of resin products on the line is required, which hinders downsizing of the manufacturing apparatus.
In addition, a traveling route for traveling 20 or more resin products and a large number of heaters arranged in the vicinity of the traveling route must be provided, and the facility cost becomes enormous, and the time-consuming spectral heat cost also increases, resulting in cost reduction. There is a problem that it takes too much.

Further, the heater must be arranged at a position where it does not interfere with the traveling of the resin product moving along the predetermined route, and the position where the heater is arranged is restricted. Therefore, a portion near the heater and a portion distant from the heater are generated in a portion where the resin product needs to be distorted, and if a portion near the heater is to be kept at a predetermined temperature, a portion distant from the heater may rise to a predetermined temperature. If this is not possible, the strain is not sufficiently removed, and if the part far from the heater is kept at a predetermined temperature, there is a problem that the part near the heater will rise in temperature above the predetermined temperature and will be deformed. is there.

[0008] Therefore, an object of the present invention is to remove the strain generated in the heat-welded portion of the resin product in a short time without requiring large equipment.

[0009]

In order to solve the above-mentioned problems, the method for annealing a resin product of the present invention raises the surface temperature of the heat-welded portion of the resin product to a target temperature by irradiating with far infrared rays. A step, and a holding step for holding the surface temperature of the heat-welded portion at the target temperature, so as to raise the internal temperature of the heat-welded portion to the target temperature or a temperature near the target temperature during the holding step. It was done.

Therefore, in the method for annealing the resin product of the present invention, the heat-welded part of the resin product is heated by the synthetic resin which can be heat-welded, that is, the far-infrared rays which are easily absorbed by the thermoplastic resin. Rises to the target temperature in a short time.

Further, after the surface temperature of the heat-welded portion of the resin product has risen to the target temperature, the process proceeds to a holding step for keeping the surface temperature of the heat-welded portion at the target temperature. It does not become abnormally higher than the temperature.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the method for annealing a resin product of the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, the present invention is an envelope (resin product) in which a lamp body of a vehicle lamp and a lens are joined by heat welding such as hot plate welding and vibration welding,
It is applied to an annealing method for removing the residual stress at the joint (thermally welded portion) between the lamp body and the lens.

Generally, ABS resin, AAS resin, or ASA resin is used for the material of the lamp body 2 of the envelope 1 having a lamp space for arranging a light source or the like inside, and the material of the lens 3 is Acrylic resin is used. As described above, the envelope 1 for a vehicle lamp is an example of a resin product that removes the residual stress of the heat-welded portion by the method of the present invention, and the resin product to which the present invention is applied is a vehicle lamp. Of course, it is not limited to the envelope. Further, the materials of the respective parts joined to each other by heat welding of the resin product are also the above-mentioned resin materials, that is, ABS resin and AAS.
It is not limited to resin, ASA resin, and acrylic resin.

The envelope 1 of the vehicular lamp is formed by joining the lamp body 2 and the peripheral portions 2a, 3a of the lens 3 by heat welding. Then, stress remains in the heat-welded portion 4 which is a joint portion between the peripheral edge portion 2a of the lamp body 2 and the peripheral edge portion 3a of the lens 3 due to the heating during the thermal welding.

A far infrared heater 5 is used to heat the heat-welded portion 4 of the envelope 1. The heater 5 is formed by embedding a heating wire 7 such as a Nicrocum wire in a base material 6 formed of ceramics, and has a parabolic shape in a vertical cross section in order to improve thermal efficiency. The area 8 surrounded by the heat generating surface 5a of 5 and the converging position F of the parabolic surface is an effective heating range (area hatched by broken lines) (see FIG. 2). In this effective heat generation range 8, the density of far infrared rays is high and the heat generation efficiency is good.

The material of the heater that radiates far infrared rays is not limited to ceramics, and the shape of the heating surface is not limited to a paraboloid.

At the position where the annealing process is executed, the movable base 9 is movable in the direction of separating from and contacting the envelope 1.
And a plurality of heaters 5, 5, ... Are provided on the moving base 9.
・ ・ Is supported. That is, the moving base 9 is the envelope 1.
A plurality of heaters 5, 5, ... Are supported by the moving base 9 so as to surround the heat-welded portion 4 of the envelope 1 when positioned close to the. Moreover, as shown in FIG. 2, the heater 5 and the heater 5 are arranged so that the heat-welded portion 4 of the envelope 1 is located in the area 8.
5, ... Are arranged.

Next, each step for removing the residual stress in the heat-welded portion 4 of the envelope 1 will be described with reference to FIG.

First, the envelope 1 is placed on the work support 10. At this time, the moving base 9 is spaced above the envelope 1 and stands by at the waiting position (see FIG. 3A). The heaters 5, 5, ... Are energized and heated to an appropriate temperature.

When the envelope 1 is placed on the work support 10, the moving base 9 is lowered and the heaters 5, 5, ... It is positioned so as to surround the heat-welded portion 4 of the container 1 (see FIGS. 1 and 3 (b)). In this state, the heat-welded portion 4 of the envelope 1 has effective heating ranges 8, 8, ... Of the heaters 5, 5 ,.
Located inside (see FIG. 2). As a result, the temperature raising step is started.

Then, when the temperature of the surface 4a of the heat-welded portion 4 reaches a target temperature, that is, about 80 ° C., which is the glass transition point of the material resin of the lamp body 2 and the lens 3, the heat-welded portion of the envelope 1 is heat-welded. The moving base 9 is raised so that the portion 4 is located outside the effective heat generating ranges 8, 8, ... Of the heaters 5, 5 ,. In this way, the holding process is started.

The envelope 1 of a standard rear combination lamp of an automobile is made of a resin product, and the heater 5 has a heating surface 5a.
Temperature of 380 ° C to 390 ° C, the heating surface 5 of the heater 5
When the distance between a and the surface 4a of the heat-welded portion 4 (see FIG. 2) is set to 20 to 40 mm, the heat-welded portion is about 5 seconds after starting the temperature raising step in the state of FIG. Surface 4a of 4
Reaches a target temperature of about 80 ° C. Then, when the temperature of the surface 4a of the heat-welded portion 4 reaches about 80 ° C, the temperature of the inner surface 4b (see FIG. 2) which is separated from the heater 5 by about 3 mm from the surface 4a becomes about 50 ° C. (See Figure 4).

By keeping the heaters 5, 5, ... away from the heat-welded portion 4, the temperature rise of the surface 4a of the heat-welded portion 4 to 80 ° C. or higher can be suppressed, while the heaters 5, 5 ,. .. By maintaining a proper distance between the heat-welded portion 4 and the heat-welded portion 4, the temperature of the surface 4a of the heat-welded portion 4 is kept constant, and the temperature of the surface 4a is transferred to the inside by heat conduction. The temperature inside the welded portion 4 rises.

In order to increase the temperature of the inner surface 4b while suppressing the temperature increase of the surface 4a of the heat-welded portion 4, as a means for adjusting the heating efficiency of the heaters 5, 5, ... Although the means for separating the heaters 5, 5, ... From the heat-welded portion 4 has been shown, the means for adjusting the heating efficiency of the heaters 5, 5, ... is to change the distance from the heat-welded portion 4. It is not limited to. For example, the heaters 5, 5,
It is possible to perform the holding step by using a thermal efficiency adjusting means other than changing the distance, such as inserting a mesh-shaped heat shield plate between the ... And the heat-welding portion 4.

The temperature of the surface 4a of the heat-welded portion 4 is set to about 80 ° C.
The rise distance of the heaters 5, 5, ... To raise the internal temperature from the position in the temperature raising step is as follows.
In the case of, it is about 50 mm.

Then, the temperature of the inner surface 4b of the heat-welded portion 4 rises to a target temperature of about 80 ° C., and after holding it for a certain period of time, the holding step is finished and the moving base 9 is raised to the standby position. (See FIG. 3 (c)).

In the case of the envelope 1 of the rear combination lamp, the temperature of the inner surface 4b of the heat-welded portion 4 reaches the target temperature (80 ° C) in about 12 to 13 seconds after the start of the temperature raising process (Fig. 4), the holding process is continued for about 17 seconds.

After completion of the holding step, the stress remaining in the heat-welded portion 4 due to heat-welding is removed by slow cooling.

According to the above-mentioned annealing method, the temperature of the heat-welded portion can be raised to and maintained at the target temperature within a short time of about 30 seconds, and the consistency with other process cycles can be obtained. It is not necessary to provide an extraordinarily space- and time-consuming position on one line, and it is possible to reduce the size of equipment and the cost of equipment and operation.

Further, since the temperature of the heat-welded portion can be raised and maintained for each resin product, the product flow on the line becomes very smooth.

Further, in the above-mentioned annealing method, since a plurality of heaters 5, 5, ... Can be arranged so as to surround the heat-welded portion 4 in accordance with the shape of the heat-welded portion 4, the heating can be performed. It is possible to heat only the portions that need to be heated without heating the portions that do not need to be heated, and it is possible to eliminate problems such as deformation due to unnecessary heating.

It should be noted that the shapes, structures, numerical values, and the like of the respective portions shown in the above-described embodiments are merely examples of the embodiment to be carried out when the present invention is carried out, and the shapes and structures of the present invention can be realized by these. The technical scope should not be limitedly interpreted.

[0033]

As is apparent from the above description, the annealing method for the resin product of the present invention is an annealing method for removing the strain generated in the heat welding part by heating the heat welding part of the resin product with a heater. In the above, a heating step of irradiating far infrared rays to raise the surface temperature of the heat-welded portion to a target temperature, and a holding step of holding the surface temperature of the heat-welded portion at the target temperature, the holding step The inside temperature of the heat-welded portion is raised to the target temperature or a temperature near the target temperature.

Therefore, in the method for annealing the resin product of the present invention, the heat-welded part of the resin product is heated by the synthetic resin which can be heat-welded, that is, the far infrared rays which are easily absorbed by the thermoplastic resin. Rises to the target temperature in a short time. Therefore, the resin product can be annealed in an extremely short time.

Further, after the surface temperature of the heat-welded portion of the resin product has risen to the target temperature, the process proceeds to a holding step of keeping the surface temperature of the heat-welded portion at the target temperature. It does not become abnormally higher than the temperature.
Therefore, the deformation of the resin product due to the abnormal temperature rise can be avoided. Since the surface temperature is transferred to the inside of the heat-welded portion by heat conduction, the internal temperature rises to the target temperature by keeping the surface temperature at the target temperature.

Further, since it is possible to anneal each resin product, the equipment can be small, and the equipment can be downsized, the cost can be reduced, and the operation cost can be reduced.

In the invention described in claim 2, the holding step is carried out by moving the heater so as to separate it from the position where the heater was located during the temperature raising step from the heat-welded portion. Simple equipment is sufficient for the process.

In the invention described in claim 3, the heater has a shape for condensing far infrared rays, and the heat-welded portion is closer to the heater than the condensing position of far infrared rays during the temperature raising step. Since it is located at the position, the temperature of the heat-welded portion can be efficiently raised.

[Brief description of drawings]

FIG. 1 shows an embodiment of an annealing method of the present invention, which is a diagram showing a planar positional relationship between a resin product and a heater.

FIG. 2 is an enlarged side view of a heater.

FIG. 3 is a diagram schematically showing the whole process, left (a)
FIG. 3 is a schematic cross-sectional view showing in order from time to right (d) in chronological order with a graph.

FIG. 4 is a graph showing changes in surface temperature and internal temperature of a heat-welded portion.

[Explanation of symbols]

1 ... Envelope (resin product), 4 ... Thermally welded part, 4a ... Surface,
4b ... inner surface (inside), 5 ... heater, F ... focusing position

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Chiharu Matsunaga             500 Kitawaki, Shimizu City, Shizuoka Prefecture Koito Co., Ltd.             Factory Shizuoka factory (72) Inventor Takeshi Furusawa             18 Fujieda O at 800 Yokouchi, Fujieda City, Shizuoka Prefecture             To Lighting Co., Ltd. F-term (reference) 4F201 AK04 AM32 AP05 BA07 BC03                       BC12 BR02 BR08 BR12 BR34                 4F211 AD05 AR06 TA01 TW06 TW15                       TW34

Claims (3)

[Claims] 1. An annealing method for heating a heat-welded portion of a resin product by a heater to remove strain generated in the heat-welded portion, the far-infrared ray being irradiated to change the surface temperature of the heat-welded portion to a target temperature. And a holding step of holding the surface temperature of the heat-welded portion at the target temperature, and the internal temperature of the heat-welded portion during the holding step is the target temperature or a temperature near the target temperature. A method of annealing a resin product, characterized by increasing the temperature to 2. The resin product according to claim 1, wherein the holding step is performed by moving the heater so as to be separated from the heat-welding portion from a position which was located during the temperature raising step. Annealing method. 3. The heater has a shape for concentrating far infrared rays, and the heat-welded portion is positioned closer to the heater than the converging position of far infrared rays during the temperature raising step. The method for annealing a resin product according to claim 1 or 2.