JPH048114B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an apparatus for heating and curing sealants such as sealers, primers, or adhesives, and is used to cure sealants applied to bodies, etc. during the manufacturing process of automobiles, for example. Used to harden materials.

(Prior art and its problems) During the manufacturing process of automobiles, many types of sealants are used for car bodies, but an important problem is how to heat and harden these sealants. be. For example, in the white body process (vehicle body assembly process), mastic adhesive, hemming adhesive, hemming sealer, spot weld sealer, etc. are applied, followed by degreasing, chemical conversion treatment, electrodeposition coating process, and sealing. The material is heated and hardened using the heat of baking the electrodeposition coating. Further, the body sealer applied to the electrodeposited surface after electrodeposition baking is then subjected to intermediate coating, intermediate coating baking, top coating, and top coating baking steps, and is cured by the heat of the intermediate coating and top coating baking.

However, according to the conventional heat curing method described above, the sealant used in the white body process deteriorates due to processing liquid and deforms due to damage from showering between the time it is applied and the time it hardens. may occur, or components of the sealant may be eluted, causing deterioration of the processing solution.
Further, sealing materials used in the painting process do not deteriorate due to treatment liquids, etc., but there is a problem in that their shape changes due to contact during the process.

The above-mentioned problem can be solved by heating and curing the applied sealant before it is influenced by the outside, but a method of heating and curing using an infrared radiator is known, for example, as proposed by Tokuko Showa. 48−8853
It is known from Japanese Patent Publication No. 57-1306.

However, the specific method disclosed in the above publication is a method using an infrared emitting laser, and a method using a gas-heated far-infrared irradiation chamber that heats a far-infrared radiation plate with combustion gas. However, not only are both methods expensive, but especially the latter method, which uses a far-infrared irradiation chamber, makes it difficult to precisely control the heating temperature, and it is difficult to efficiently heat and harden only the area to be heated. I can't let it happen.

(Means for Solving the Problems) In view of the above-mentioned problems, the present invention does not require large-scale equipment, is suitable for efficiently heating and curing sealants, and is inexpensive even during the manufacturing process of automobiles. The present invention provides a simple heat curing device for a sealant that can be incorporated into a device, and the technical means for this purpose will be described with reference numerals in the embodiments described later. It is a heating curing device for sealing material 3 applied along a coating trajectory, and is equipped with a near-infrared radiation electric heater 4 equipped with a near-infrared radiation lamp 8 and a reflector 7 that concentrates radiation energy on the heating target area. The heater 4 is arranged along the application trajectory of the sealant 3 at a distance from the material W, and locally heats the heating target portion to which the sealant 3 is applied by near infrared rays emitted from the heater 4; A temperature sensor 11 that indirectly or directly detects the temperature of the heating target part is arranged, and the detected temperature of this temperature sensor 11 and a set temperature are compared, and a fixed period having an on width proportional to the temperature difference is determined. A control means 10 for generating a pulse signal is provided, and an on/off element 9 interposed in the power supply circuit of the heater 4 is controlled to be turned on or off by the pulse signal.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In FIGS. 1 and 2, materials to be coated (workpieces) W placed on pallets 2 are sequentially conveyed on an intermittent conveyor 1 to a station S for a curing process in which a sealant 3 is heated and hardened. position and stand still. The material to be coated W is an automobile door made of sheet metal processed from a steel plate, and in the previous process, a sealant was applied with a substantially linear coating trajectory along the folded edge of the upper surface. It is something that

As shown in FIG. 3, a near-infrared electric heater 4 is placed above the sealant 3 of the positioned workpiece W along the longitudinal direction of the sealant 3 at a certain distance from the workpiece W. is attached to a bracket 5 fixed to the frame of the conveyor 1 or the like. The near-infrared electric heater 4 includes a rectangular parallelepiped box-shaped case 6, which is equipped with a reflector 7 whose surface is plated with gold, and a rod-shaped near-infrared radiation lamp 8 is attached to the focal point of the reflector 7. A glass window 9 is provided at the opening, and although not shown, an inlet/outlet for cooling water is provided on the outer surface of the case 6. When this near-infrared electric heater 4 is energized, it emits near-infrared rays from a near-infrared radiation lamp 8, and the radiant energy is reflected downward by a reflector 7, thereby damaging the sealing material 3 and its surrounding area. The steel plate is heated locally.

In FIG. 4, the near-infrared radiation lamp 8 is operated via an on/off element 9 such as a bidirectional thyristor.
Connected to AC200V power supply. A temperature sensor 11 such as a thermocouple is installed in the vicinity of the sealing material 3 to detect the ambient temperature thereof, and its detected temperature signal is input to the control means 10.

That is, the control means 10 includes an amplifying section 12, a setting device 1
3. Consisting of comparators 14 and 15, the signal from the temperature sensor 11 is amplified by the amplification section 12, and then compared by the comparator 14 with the value set by the temperature setting device 13.
A voltage signal S1 is outputted according to the difference between the temperature detected by 1 and the set temperature. This signal S1 is input to the comparator 15, where it is compared with a triangular wave of a constant period, undergoes pulse width modulation, and generates a pulse signal S2 with an on-width proportional to the magnitude of the signal S1 (difference between the detected temperature and the set temperature). The comparator 15 outputs the signal. This pulse signal S2 is applied to the gate of the on-off element (bidirectional thyristor) 9, and a power supply voltage is applied to the near-infrared radiation lamp 8 only during the on-time of the pulse signal S2, thereby controlling the temperature. ing.

According to the embodiments described above, for example, the sealant 3
Using a PVC plastisol body sealer and a near-infrared radiation lamp 8 with an output of 980W,
If the distance between the sealant 3 and the near-infrared electric heater 4 is 10 mm, the sealant 3 will be removed in about 5 seconds.
The entire area is hardened. Also, the distance is 20mm, 40mm, 60mm,
7 seconds for 80mm and 100mm, respectively.
The entire area was cured in 11 seconds, 15 seconds, 20 seconds, and 27 seconds. Therefore, with the material W to be coated positioned as shown in FIGS. 1 and 2, the near-infrared electric heater 4
By heating only the sealing material 3 and the vicinity of the sealing material 3 locally, the sealing material 3 is heated in a short time.
can be cured. Since the near-infrared electric heater 4 can be installed in the station S for the curing process, there is no need for large-scale equipment, and it can be installed immediately after the application process of applying the sealant 3. There is no possibility that the sealing material 3 will come into contact with other members or the like and change its shape before it hardens, and the sealing material 3 and other processing liquids will not deteriorate during the process.

In the above-mentioned embodiment, an example was shown in which the sealant 3 was applied to the upper surface of the material W to be coated and cured by heating, but as shown in FIG. The heated material may be heated through the steel plate of the material W to be coated. Alternatively, as shown in FIG. 6, the steel plate may be folded back at the hemming portion (edge) and the sealing material 3 may be sandwiched between the steel plates. In the above example, 1
Although we have described an example in which the material to be coated W is heated from only one side with two near-infrared electric heaters 4, it is also possible to heat both sides (upper and lower surfaces) of the material to be coated W using two near-infrared electric heaters 4. You can do it like this. In this case, each near-infrared radiation lamp 8 may be provided with an on/off element 9, a temperature sensor 11, and a control means 10 to perform temperature control.

The temperature sensor 11 includes a near-infrared radiation lamp 8,
The temperature may be detected by bringing it into contact with the sealing material 3 or the steel plate of the material W to be coated.Alternatively, an object having a specific heat similar to that of the sealing material 3 or the steel plate may be attached to the temperature sensor 11 and the temperature may be detected in the vicinity of the material W. It may be arranged at a position where it is heated by the infrared electric heater 4 under the same conditions as the sealing material 3, and the temperature may be detected without contacting anything else. Near-infrared electric heater 4
In the following, we have explained an example in which near-infrared rays are emitted in parallel by the reflector 7, but the center (part to be heated)
Of course, it is also possible to radiate the radiation so as to concentrate it on the area.

In the above embodiment, an example was explained in which the near-infrared electric heater 4 was fixed to the bracket 5, but the near-infrared electric heater 4 may be attached to the tip of the arm of the robot and placed at an appropriate position relative to the material W to be coated. In addition, in the process of applying the sealant 3 to the material W to be applied, the application is performed by a robot, and a near-infrared electric heater 4 is attached to the same robot. It is also possible to heat and harden immediately after.

(Operations and Effects of the Invention) As described above, the sealing material heating curing apparatus of the present invention uses a near-infrared radiation electric heater that is equipped with a near-infrared radiation lamp and a reflector that concentrates radiation energy on a heating target portion. Since it is possible to locally heat the area to be heated, including the sealant, to harden the sealant, it is possible to use a far-infrared irradiation room while using a cheaper and simpler heating means than an infrared laser. There is no unnecessary heating and damage to parts other than the sealant, unlike when using a far-infrared irradiation chamber, and there is no need for large-scale equipment to apply the sealant. It is also easy to incorporate a heat curing process immediately after the coating process, and the sealing material can be heat cured efficiently and easily in a short time.

Furthermore, according to the present invention, a circuit is provided which compares the detected temperature of the temperature sensor with a set temperature and generates a pulse signal of a constant period having an on width proportional to the temperature difference, and a circuit is provided in the power supply circuit of the heater. Since the on/off element installed in the heater is controlled on/off by the pulse signal, the temperature can be controlled by operating the near-infrared electric heater intermittently in extremely short cycles, and the temperature can be controlled in a very short time after energization. By using the near-infrared electric heater, which has the characteristic of reaching a high temperature and returning to room temperature in a very short time after the power is turned off, it is easy to heat the sealing material to be heated to an appropriate temperature and cure it well.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a plan view of the station S for the curing process, FIG. 2 is a side view taken in the direction of the arrow in FIG. 1, and FIG. 3 is an enlarged view of the main part of FIG. 2. , FIG. 4 is a circuit diagram showing an example of a control circuit for a near-infrared radiation lamp, and FIGS.
FIG. 3 is a side view showing another example of the position and shape of the sealant. 3...Sealing material, 4...Near infrared electric heater, 7...Reflector, 8...Near infrared radiation lamp,
9...On-off element such as bidirectional thyristor, 10
... Control means, 11 ... Temperature sensor such as thermocouple, 12 ... Amplifying section, 13 ... Temperature setting device, 1
4, 15... Comparator, W... Material to be coated (work).

Claims (1)

[Claims] 1. A heating curing device for applying a sealant along a predetermined application trajectory on the surface of a material to be applied,
A near-infrared radiating electric heater equipped with a near-infrared radiating lamp and a reflector that concentrates radiant energy on the heating target area is placed along the sealing material application trajectory at a distance from the material to be coated, and the heater is The heating target area coated with the sealing material is locally heated by near infrared rays emitted from the heating target area, and a temperature sensor that indirectly or directly detects the temperature of the heating target area is arranged, and the temperature sensor detects the temperature of the heating target area. A circuit is provided that compares the temperature with a set temperature and generates a pulse signal of a constant period with an on width proportional to the temperature difference, and turns on and off an on/off element interposed in the power supply circuit of the heater using the pulse signal. A controllable heat curing device for sealing material.