JPS5928759B2 - Integral molding method of fan casing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a fan casing that is integrally molded by injecting foam insulation material between the inner and outer boxes, and in particular, the inner case for guiding ventilation is formed with a heat-resistant layout. This allows it to be used as a fan casing for high-temperature hot air.

EMBODIMENT OF THE INVENTION The case where one Example of this invention is applied to the air conditioner for heat pumps is demonstrated based on drawing below.

Figure 1 is a longitudinal cross-sectional view of a heat pump air conditioner, in which 1 is a heat exchanger that acts as an evaporator (cooler) during cooling and a condenser (heater) during heating, and 2 is an auxiliary heating source during heating. The working electric heater 3 is a fan casing that uses a cross-flow fan 4 to draw indoor air from the suction grille 5 at the upper front to the outlet 6 at the lower front. This fan casing 3 consists of an inner box T for ventilation guidance made of a heat-resistant layer such as a metal plate formed by heat-insulating foam molding, which will be described later, and an outer box 8 made of a soft low-foaming thin film material such as expanded polyethylene foam. It is an integrally molded product formed from a urethane foam insulation material 9 injected and foamed inside, and the foam insulation material 9 reliably insulates low-temperature air during cooling and high-temperature hot air during heating from the outside. In addition, by forming the inner box 7 with a heat-resistant layout, even if the indoor induced air is heated to an extremely high temperature together with the heat exchanger 1 by the electric heater 2 during heating, it may lead to a fire such as burnout, resulting in a dangerous operating condition. This was designed to prevent this from happening.

Figure 2 is an exploded cross-sectional view showing the fan casing 3 when it is formed into heat-insulating foam molding, and Figure 3 is an assembled cross-sectional view of the fan casing 3. Prepare an outer box 8 made of foam, especially the outer box 8.
As shown in FIG. 4, after cutting a commercially available polyethylene foam 10 with a thickness of 6 nm into two halves with a wall thickness of 3 inches,
A mold was made in advance by vacuum forming this thin film with a wall thickness of 3 mm by heating it from both sides to make it flexible.

The expanded polyethylene foam 10, which is on the market as a commercial product, is a foamed sheet made by rolling a mixture of polyethylene resin and foaming material with rollers and then foaming it in a heating furnace. The front and back surfaces 11, 11 have smooth surfaces generally called skin layers.

In addition, the expanded polyethylene foam 10 includes foamed products with different expansion ratios, such as 30 times foamed products with a high mixing ratio of foaming materials, low expansion ratio products with a lower mixing ratio, such as 20x and 10x. A 30x foamed product with a high expansion ratio has many bubbles and is easily deformed because these bubbles are connected to each other. On the other hand, foamed polyethylene foam with a low expansion ratio of, for example, 20 times, has fewer bubbles than a foamed product of 30 times, and the bubbles are independent and dense as shown in FIG. 4, so that it is difficult to deform. Therefore, as mentioned above, the mold is made by vacuum forming with a thickness of 3m7! For the thin film material of L, it is necessary to select and use foamed polyethylene foam 10 with a low expansion ratio of 20 times, for example, which is hard to deform and is difficult to deform.However, low expansion ratio products, on the other hand, lack polarity and have poor adhesive strength with the insulation foam stock solution. Since the foamed polyethylene foam 10 is cut into two halves, this cut surface 13 (because it is a foam, the air bubbles 12 are exposed and has a rough surface shape) is used to form the outer box 8 during vacuum forming.
As shown in FIG. 5, it is necessary to infiltrate and harden the heat insulating foaming solution into the half-split air bubbles 12 appearing on the cut surface 13 to ensure adhesion. be. Considering this point, the inner case 7, outer case 8, and outer mold jig 16 can be sequentially overturned from above to the inner mold jig 15, and the jig 1
When molds 5 and 16 are clamped together, the strong outer case 8 made of 20 times foamed material maintains contact with the outer mold jig 16 without being deformed, and maintains a gap 17 with the inner case 7.

Therefore, the urethane foam insulation stock solution can be reliably injected into this gap 17 from the injection hole 18 of the outer mold jig 16 and the outer box 8, and as described above, the urethane foam insulation stock solution can be injected into the half-split air bubble portion 12. The foam hardens and becomes firmly adhered to both the inner box 7 and the outer box 8, and when both jigs 15 and 16 are removed, the urethane foam forms between the inner and outer boxes 7 and 8 as shown in Figure 1. The fan casing 3 can be molded as a single piece with a heat insulating material 9 interposed therebetween. In addition, during the above-mentioned foam molding, the injected urethane foam insulation stock solution flows on the smooth surface of the iron plate of the inner case 7, so it is spread evenly, filled and foamed without any resistance, and the mold is clamped away from the injection hole 18. By making the portion 19 slightly thicker, air can be easily removed during foaming.

This outer box is made of a thin film material with a low expansion ratio, and since the film material has few closed cells and is densely packed, it is less likely that the foamed heat insulating material will seep into the film.

In the conventional molding method using integral foaming, the inner box 7 is formed from foamed polyethylene foam 10 and the outer box 8 is formed from a drawn iron plate, and a foamed insulation stock solution is injected between the inner and outer boxes 7 and 8 from the outer box 8 side. It is well known that foaming occurs, and in such a molding method, the foamed polyethylene foam 10 is pressure-molded onto the inner mold jig 15 under foaming pressure, so that the foamed polyethylene foam 10 can be molded at a foaming ratio as in the method according to the present invention described above. Although it is not necessary to select a type with a low temperature or to make a mold in advance by vacuum forming, in the structure of a fan casing in which the inner case 7 is formed of foamed polyethylene foam 10, this foamed polyethylene foam 10 is used as described above. There is a fundamental drawback that it cannot be used in a heat pump type air conditioner because there is a risk of burning out due to heating of the electric heater 2 during heating and leading to a fire. For this reason, as an alternative method, as shown in the chain line in FIG.
When formed on the inner mold jig 15 and the iron plate inner box 7 side, the foamed polyethylene foam 10 can be crimped onto the outer mold jig 16 with foaming pressure as in the conventional method described above, and it is necessary to select a material with a low foaming ratio. Also, there is no need to make a mold in advance by vacuum forming, but since the foam insulation material 9 will be exposed from the injection hole 18' of the inner case 7 after foam molding, this injection hole 1 will be covered with a separate member made of iron plate. If it is not installed so that it is flush with the outer surface of the inner box 7, it will create ventilation resistance and lead to turbulence and noise, so precision is required in the post-processing. In addition, in the past, a sheet of urethane foam was simply pasted on the outer wall of the inner box 7 made of iron plate for insulation, but this had the disadvantage that it could not be stuck tightly and was easily peeled off. Furthermore, because the heat insulating effect was poor, the adhesive had to be thick, making it unsuitable for heat pump air conditioners, which required a thinner design.

In view of these points, the present invention, as explained above, consists of an inner box for ventilation guidance made of a heat-resistant rigid material that can withstand high temperatures, and an outer case made of a soft, low-foaming thin film material that does not easily deform. The inner surface of the box has a rough surface shape that facilitates surface adhesion to the foamed heat insulating material.

Therefore, by injecting and foaming the foamed heat insulating material into both boxes from the outer case side, this heat insulating material penetrates into the air bubbles of the outer case, and the heat insulating material and the outer case are bonded securely in a state of surface adhesion. By doing so, we can obtain an integrally molded fan casing.
It is extremely suitable for thin heat pump type air conditioners.
In addition, this outer box is made of a thin film material with a low expansion ratio, and since the bubbles are made independent and the number of closed bubbles is kept small, there is little possibility that the bubbles will connect with each other.

Therefore, the heat insulating material does not leak through the bubbles to the surface of the outer case, so the molded product can be easily separated from the jig without the heat insulating material sticking to the jig.

[Brief explanation of drawings]

Each of the drawings shows an embodiment of the present invention; Fig. 1 is a longitudinal cross-sectional view of a heat pump type air conditioner, Fig. 2 is an exploded cross-sectional view showing the fan casing during insulation foam molding, and Fig. 3 is the same. ○3...Fan casing ,7...
Inner box, 8...Outer box, 9...Foam insulation material, 14...Inner surface of outer box.

Claims (1)

[Claims] 1 The inner box for ventilation guidance is made of a heat-resistant rigid material, and the outer case is made of a soft, low-foaming thin film material, and the inner surface of the outer box is made of a material that is cut in half to expose the closed-cell portion. A foamed heat insulating material is injected and foamed into both the inner and outer boxes, and the foamed heat insulating material penetrates into the closed cell portion, thereby bonding the outer case and the foamed heat insulating material surface-to-face. A method of integrally molding a fan casing.