JPH0248074Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a printing machine such as a rotogravure printing machine or an offset rotary printing machine, or a coating machine such as a coating machine or a laminator, for printing or coating on a continuous strip of paper, film, etc. The present invention relates to a hot air nozzle used in a drying device for drying or heat-treating the air after drying.

Conventionally, this type of drying equipment has generally been of the nozzle jet type, in which hot air is blown at high speed at right angles to the object to be dried, in order to quickly dry the moving strip (hereinafter referred to as the object to be dried). As a hot air nozzle, a slit nozzle with an elongated outlet was used. As a result of various studies to further improve the heat transfer performance of the nozzle jet method, the inventors of the present invention have developed a method for drying using a perforated plate nozzle, which has a perforated plate with a large number of hot air blowing holes at the tip of the nozzle, instead of the conventional slit nozzle. Developed the device. As shown in FIG. 1, this drying device has a plurality of perforated plate nozzles 3 each having a perforated plate 2 having a wider dimension L in the transport direction of the dried material 1 than a conventional slit nozzle. The exhaust channels 4 are arranged alternately along the same line, and have the advantage of having better heat transfer performance than the conventional ones. By the way, to make the most of this drying device's capabilities,
The hole diameter d of the perforated plate is 3 to 6 mm, and the hole spacing L is 15 to 45.
mm, the distance z between the perforated plate 2 and the material to be dried 1 is 4 to 10
mm, z/d from 1 to 3, dimension L of perforated plate 2 from 50 to
250 mm, the ratio of the total cross-sectional area of the holes to the surface area of the material to be dried in the drying device, that is, the open area ratio is 1.5 to 3%.
It is preferable that the hot air be blown out from the holes of the perforated plate 2 at a speed of 20 to 50 m/s. However, when hot air is blown out from the perforated plate 2 at such a high speed, the perforated plate generates a whistle-like "beep" sound, and this sound increases as the wind speed increases and contains more high-frequency components. It was found that the noise was extremely harsh and unbearable for workers.

The inventor of the present invention conducted various studies in order to reduce the sound generated from such a perforated plate, and found that the generation of sound can be effectively prevented by simply providing a tapered portion on the air inlet side of the air outlet of the perforated plate. Ta.

The present invention was made based on this knowledge, and in the hot air drying device of a printing machine or coating machine,
The hot air nozzle is arranged alternately with the exhaust flow path along the transport direction of the strip-shaped material to be dried, and has a perforated plate having a large number of hot air blowing holes at the tip, and the hot air blowing hole is on the hot air inlet side. The gist is a hot air nozzle characterized by having a tapered part.

Hereinafter, the present invention will be described in more detail with reference to the drawings. Similar to the perforated plate nozzle 3 shown in Fig. 1, the hot air nozzle according to the present invention is arranged alternately with the exhaust flow path along the direction of transport of the material to be dried, and has a large number of hot air blowing holes at the tip. It has a perforated plate.
By the way, a normal perforated plate 2 uses straight holes 5 as shown in FIG. When air is blown out from the holes 5, there is no problem at low speeds, for example, 10 m/s or less, but it has been found that when the speed exceeds 20 m/s, intolerable noise occurs as described above. Therefore, in the present invention, as shown in FIG. 3, a tapered portion 5A is formed on the hot air inlet side of the hot air outlet 5 of the perforated plate 2 at the tip of the hot air nozzle. It has been confirmed that this tapered portion 5A exhibits a surprising sound-dampening effect, and generates almost no sound even when hot air is blown out in the direction indicated by arrow A at high speed, for example, at 20 to 50 m/s.
Moreover, the tapered portion not only has the effect of muffling noise, but also has the effect of reducing pressure loss, and it was confirmed that the pressure loss was reduced by about 20%. In addition, in order for the tapered portion 5A to exhibit a good noise reduction effect, the taper angle θ must be
Preferably it is between 60 and 120 degrees, most preferably 90 degrees. Also, the taper depth t is the perforated plate thickness T1
~3mm, about 0.5mm is sufficient.

The tapered portion 5A of the hot air outlet 5 may be formed by ordinary drilling, but when forming a perforated plate by punching, a tapered portion may be provided on the punch for punching the holes and the taper portion 5A can be formed at the same time as punching the holes. The tapered portion may also be processed.

As described above, the hot air nozzle of the present invention is a perforated plate nozzle equipped with a large number of hot air blowing holes with a tapered part on the hot air inlet side, so it can blow out hot air at high speed with almost no noise, and it can be This has the excellent effect of making it possible to create a drying device with good thermal performance and low noise.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view schematically showing a part of the drying device developed by the present inventor, Fig. 2 is a cross-sectional view showing the holes of a normal perforated plate, and Fig. 3 is a perforated plate of the hot air nozzle of the present invention. FIG. 1... Material to be dried, 2... Perforated plate, 3... Perforated plate nozzle (hot air nozzle), 4... Exhaust flow path, 5...
Hole, 5A...Tapered part.

Claims (1)

[Scope of utility model registration request] In a hot air drying device of a printing machine or coating machine, hot air nozzles are arranged alternately with exhaust channels along the conveying direction of a strip-shaped material to be dried, and a perforated plate having a large number of hot air blowing holes at the tip thereof is used. A hot air nozzle, wherein the hot air blowing hole has a tapered portion on the hot air inlet side.