Flexible duct for air conditioner and method for manufacturing the same

Abstract

To securely suppress generation of a large pleat on an inner surface material in a bent portion of an air-conditioning flexible duct by using simple and inexpensive means and reduce pressure loss.SOLUTION: A spirally cylindrical inner surface material 12 is formed by spirally winding a core material 11 and spirally winding and stretching between pitches of the core material 11 a non-woven fabric or resin film band material 15. An air-conditioning flexible duct 1 is manufactured by coating an outer periphery of the inner surface material 12 with a soft heat insulating layer 13. Before the coating process, a spiral band-shaped hot melt adhesive layer 16 is formed by applying a hot melt adhesive 16a with constant width W16 to an intermediate part in the width direction of the band material 15.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention mainly relates to air conditioning equipment installed in buildings, and particularly relates to a flexible duct that can be freely bent and deformed and a method for manufacturing the same.

Background Art

[0002] Generally, buildings such as office buildings and single-family houses are provided with air conditioning equipment for heating, cooling, ventilation, etc. The air conditioning equipment is provided with a duct through which air passes. As this type of duct, a flexible duct for air conditioning that is flexible and can be freely bent and deformed is known (see Patent Documents 1, 2, etc.). For example, the flexible ducts for air conditioning in Patent Documents 1 and 2 have a soft heat insulation layer covering the outer periphery of an inner surface material that is kept in a cylindrical shape by a spiral metal core material. The inner surface material is composed of a strip material of non-woven fabric or resin film, and the strip material is wound in a spiral shape and stretched between the pitches of the core material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] This type of flexible duct for air conditioning is, for example, piped in the ceiling space of a building. On the other hand, depending on the structure of the ceiling space and the arrangement of the air conditioning equipment, etc., it may be necessary to bend a part of the flexible duct for air conditioning. Particularly in the inner circumferential side part of the bent portion, the soft heat insulating layer is compressed in the duct axis direction and bulges toward the inner circumferential side in the duct diameter direction. Along with this, the inner surface material loosens in the duct axis direction and is folded into ridges toward the inner circumferential side in the duct diameter direction, forming large folds. For this reason, the flow of air in the duct becomes turbulent near the inner circumference of the inner circumferential side part, and pressure loss is likely to occur. To suppress the folds, it is conceivable to attach an adhesive tape to the inner surface material, but the automatic attaching means for the adhesive tape is expected to become a complicated mechanical mechanism, increasing the equipment cost. On the other hand, manual attachment is time-consuming and the quality is likely to vary depending on the skill level of the operator. In view of such circumstances, an object of the present invention is to surely suppress the formation of large folds in the inner surface material at the bent portion of the flexible duct for air conditioning by simple and inexpensive means and reduce the pressure loss.

Means for Solving the Problem

[0005] To solve the above problems, the flexible duct for air conditioning according to the present invention includes a spiral core material, a spiral cylindrical inner surface material made of a non-woven fabric or a resin film strip wound spirally and stretched between the pitches of the core material, and a soft heat insulating layer covering the outer circumferences of the core material and the inner surface material, and is characterized in that a spiral strip-shaped hot melt adhesive layer is coated on the middle portion in the width direction of the strip material.

[0006] According to the flexible duct for air conditioning, the hot melt adhesive layer makes the middle portion in the width direction of the strip material constituting the inner surface material harder than the end portions in the width direction. For this reason, in the inner circumferential side part of the bent portion of the flexible duct for air conditioning, the soft heat insulating layer's tendency to bulge toward the inner circumferential side in the duct diameter direction can be pressed down by the inner surface material, and the formation of large folds in the inner surface material can be suppressed, making the inner circumferential surface of the inner circumferential side part relatively smooth. As a result, the flow of air in the duct can be suppressed from becoming turbulent near the inner circumferential side part, and the pressure loss can be reduced. In the manufacturing equipment for flexible ducts for air conditioning, a hot melt adhesive application nozzle is preferably provided on the line that conveys the strip material before molding, or on the inner surface material after molding into a spiral tube. There is no need for a complex mechanical mechanism, and increases in equipment costs can be suppressed. Even when applying by hand, there is little variation in quality. In addition, the thickness and width of the hot melt adhesive layer can be easily adjusted by setting the amount of hot melt adhesive applied, the nozzle width, etc. Preferably, the hot melt adhesive has a quick drying property. This allows the next step to be carried out quickly after the hot melt adhesive is applied during the manufacture of the flexible duct for air conditioning. It is possible to avoid the risk of unnecessary parts being bonded by the hot melt adhesive. For example, it is possible to prevent different parts of the strip-shaped nonwoven fabric or resin film from sticking to each other, or to prevent the inner surface material from sticking to the soft insulation layer. Preferably, the hot melt adhesive layer has elasticity, which ensures the flexibility of the air-conditioning flexible duct.

[0007] The width of the hot melt adhesive layer is preferably 50% to 90%, more preferably 60% to 80%, of the effective width of the strip material, which reliably prevents the soft insulation layer on the inner periphery side of the bent portion from expanding radially inwardly of the duct, thereby reliably reducing pressure loss. The effective width of the strip material refers to the width dimension obtained by subtracting the fastening width (crimping allowance) on both sides from the total width of the strip material.

[0008] The method for manufacturing a flexible duct for air conditioning according to the present invention includes a step of spirally winding a core material, and a step of spirally winding a strip of nonwoven fabric or resin film and stretching it between the pitches of the core material to form a spiral cylindrical inner surface material, and a step of covering an outer periphery of the inner surface material with a soft heat insulating layer, The method is characterized in that, before the covering step, a hot melt adhesive is applied to a central portion of the strip in the width direction thereof with a constant width to form a hot melt adhesive layer in the shape of a spiral strip. Before the forming step, the coating step may be performed, or after the forming step, the coating step may be performed.

Advantages of the Invention

[0009] According to the present invention, it is possible to reliably suppress the formation of large pleats on the inner surface material in the bent portion of the flexible duct for air conditioning by simple and inexpensive means, and reduce the pressure loss in the bent portion.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. <First Embodiment (FIGS. 1 to 5)> FIG. 1 shows a flexible duct 1 for air conditioning used as piping for air conditioning equipment in buildings such as office buildings, factories, detached houses, and apartment houses. The flexible duct 1 for air conditioning is a lightweight and flexible air conditioning pipe, and extends from a heating, ventilation, and air conditioning unit (not shown) or a ventilation device to an air conditioning area. The flexible duct 1 for air conditioning includes a core material 11, an inner surface material 12, a soft heat insulating layer 13, and a surface sheet 14.

[0012] The core material 11 is made of a thin plate material made of metal such as steel or iron, and is formed into a spiral shape. As shown in Fig. 2, the cross-sectional shape of the core material 11 is formed into a C-shaped cross section in order to fasten the inner surface material 12.

[0013] As shown in FIG. 1, the inner surface material 12 is composed of a band material 15 wound in a spiral shape and formed into a spiral tube shape. The material of the band material 15 is nonwoven fabric, but is not limited to this, and may be a resin film such as polyethylene terephthalate (PET). The band material 15 is wound in a spiral shape and stretched between the pitches of the core material 11. As shown in FIG. 2, adjacent end edges 15e and 15f of the spirally wound band material 15, which are shifted by one pitch from each other, are crimped and fixed by the core material 11. The core material 11 maintains the shape of the band material 15 and the inner surface material 12 in a spiral tube shape. As shown in FIG. 1 and FIG. 5, the width W of the portion 15a of the band material 15 appearing between the pitches of the core material 11 is 15e. 15a is the total width W of the strip 15 15 Width W of both edges 15e and 15f 15e ,W 15f In other words, the size is the size minus the fastening width (crimping allowance) (W 15a =W 15 -(W 15e +W 15f )) The width W of the portion 15a of the strip 15 appearing between the pitches of the core material 11 15a is the effective width of the strip 15.

[0014] 1, the strip material 15 constituting the inner surface material 12 is coated with a hot melt adhesive layer 16. The hot melt adhesive layer 16 is disposed preferably at the middle part in the width direction of the outer peripheral side surface of the strip material 15, extends spirally in parallel with the strip material 15 and the core material 11, and is formed in the shape of a spiral belt of a constant width.

[0015] As shown in FIG. 1, the width W of the hot melt adhesive layer 16 16 is the effective width W of the strip 15 15a Preferably, it is 50% to 90% (W 15a ×0.5≦W 16 ≦W 15a ×0.9). As shown in FIG. 2, the thickness t of the hot-melt adhesive layer 16 16 is preferably about t 16 = 1 μm to 1 mm.

[0016] Examples of the components contained in the hot-melt adhesive 16a constituting the hot-melt adhesive layer 16 include styrene-based thermoplastic elastomers and olefin-based thermoplastic elastomers. The hot-melt adhesive 16a is melted and fluidized by heating, and cured by cooling and heat dissipation. Preferably, the hot-melt adhesive 16a has a quick-drying property of curing within several seconds to several tens of seconds at room temperature after being applied in a heated and melted state. The hot-melt adhesive layer 16 formed by curing the hot-melt adhesive 16a preferably has elasticity.

[0017] Both end portions in the width direction of the strip material 15 are non-coated portions 17 where the hot-melt adhesive layer 16 is not coated. The non-coated portion 17 is interposed between the core material 11 and the hot-melt adhesive layer 16.

[0018] As shown in FIG. 1, the outer peripheries of the core material 11 and the inner surface material 12 are covered by a thick-walled cylindrical soft heat-insulating layer 13. The soft heat-insulating layer 13 is composed of a soft heat-insulating material such as glass wool, for example. The soft heat-insulating layer 13 also covers the hot-melt adhesive layer 16 on the outer peripheral surface of the inner surface material 12. In other words, a hot-melt adhesive layer 16 is interposed between the soft heat-insulating layer 13 and the inner surface material 12. However, the soft heat-insulating layer 13 and the hot-melt adhesive layer 16 are merely in contact with each other and not adhered. That is, the soft heat-insulating layer 13 and the inner surface material 12 are not adhered by the hot-melt adhesive layer 16.

[0019] The outer periphery of the soft heat-insulating layer 13 is covered by a thin-walled cylindrical surface sheet 14. The surface sheet 14 includes a resin layer such as polyethylene or polyethylene terephthalate, and may further include a metal layer such as aluminum.

[0020] The flexible duct 1 for air conditioning is manufactured as follows. <Automatic forming machine 20> As shown in FIGS. 4 and 5, the forming of the core material 11 and the inner surface material 12 is automatically performed by a dedicated automatic forming machine 20. As shown by the arrow line a, the core material 11 is sent to the forming part 23 along the line 21, and as shown by the arrow line b, the strip material 15 is sent to the forming part 23 along the line 22.

[0021] <Hot melt adhesive application line 30> A hot melt adhesive application line 30 is connected to the strip material line 22 in the front stage (left side in FIG. 4) of the forming part 23. The application line 30 includes a supply source 31 of the hot melt adhesive 16a and an application nozzle 33. The application nozzle 33 faces the outer peripheral side surface (upper surface in FIG. 4) of the strip material 15 on the line 22. Preferably, the application nozzle 33 is a non-contact type nozzle. The tip (lower end in FIG. 4) of the application nozzle 33 is arranged at a slight distance from the strip material 15. The non-contact type application nozzle 33 discharges the molten hot melt adhesive 16a by the force of air. Note that, as the application nozzle, a contact type nozzle that contacts the strip material 15 and applies the molten hot melt adhesive 16a may be used.

[0022] A slot-shaped discharge port 34 is provided at the tip of the application nozzle 33. The longitudinal direction of the discharge port 34 is directed in the width direction of the strip material 15 on the line 22. Note that the discharge port at the tip of the application nozzle 33 may be a plurality of spot-shaped discharge ports arranged in the width direction of the strip material 15 instead of a slot shape.

[0023] <Coating process> The hot melt adhesive 16a heated and melted at the supply source 31 is supplied to the application nozzle 33. The hot melt adhesive 16a is discharged from the discharge port 34 of the application nozzle 33 and is widely applied to the middle part in the width direction of the outer peripheral side surface of the strip material 15. That is, the coating process is executed before the coating process described later and further before the forming process. Since the hot melt adhesive 16a is quick-drying, it cures in a very short time on the surface of the strip 15 to form the hot melt adhesive layer 16. Therefore, it is possible to quickly proceed to the next step. The hot melt adhesive application line 30 including the application nozzle 33 has a simple structure and can suppress an increase in equipment costs. By setting the slot length of the discharge port 34 of the application nozzle 33, the width W of the hot melt adhesive layer 16 16 can be adjusted. By the application flow rate of the hot melt adhesive 16a and the feeding speed of the strip 15, the thickness t of the hot melt adhesive layer 16 16 can be adjusted. In addition, in order to accelerate the curing of the hot melt adhesive 16a, a cooling part such as an air-cooling fan may be provided downstream of the application nozzle 33 in the strip line 22.

[0024] <Forming process> The strip 15 on which the hot melt adhesive layer 16 is formed is introduced into the forming part 23. Separately, the core material 11 is introduced into the forming part 23. In the forming part 23, the core material 11 is wound spirally, and the strip 15 is wound spirally and stretched between the pitches of the core material 11 to be formed into a spiral cylindrical inner material 12. As shown by the arrow line c, the formed inner material 12 is sequentially fed to the downstream (right side in FIG. 5) while being rotated about the axis.

[0025] More specifically, in the forming part 23, the edge portions 15f and 15e adjacent to each other between the forming part introduction portion of the strip 15 and the portion already formed into a spiral cylinder are overlapped, and the core material 11 is caulked in a C-shaped cross section so as to wrap the overlapped edge portions 15f and 15e. Thereby, the overlapped edge portions 15f and 15e are fixed. Although detailed illustration is omitted, in order to facilitate the fixing operation, even if the strip 15 is temporarily bent into a round loop shape or folded in half in the width direction (see Patent Document 2), since the quick-drying hot melt adhesive 16a has already cured, the both side portions in the width direction of the strip 15 are not adhered to each other by the hot melt adhesive 16a.

[0026] <Coating process> The outer peripheral surface of the inner surface material 12 formed in this way is coated with a soft heat insulating material 13 with a surface sheet 14. Since the hot melt adhesive 16a has already hardened, the soft heat insulating layer 13 and the inner surface material 12 are not adhered by the hot melt adhesive 16a.

[0027] <Pipe installation> As shown in FIG. 1, the produced flexible duct 1 for air conditioning is piped to the ceiling space of a building or the like. Depending on the location, the flexible duct 1 for air conditioning is bent. Since the hot melt adhesive layer 16 has elasticity, the flexibility of the flexible duct 1 for air conditioning is not impaired.

[0028] The inner surface material 12 and the soft heat insulating material 13 on the outer circumferential side portion 10a of the bent portion 10 of the flexible duct 1 for air conditioning are in a stretched state, and the inner surface material 12 and the soft heat insulating material 13 on the inner circumferential side portion 10b are in a slack state or a compressed state in the duct axis direction. Specifically, as shown in FIG. 3, the soft heat insulating layer 13 on the inner circumferential side portion 10b is compressed in the duct axis direction, and the heat insulating layer portion 13b between the pitches of the core materials 11 tends to bulge toward the inner circumferential side in the duct diameter direction as shown by the two-dot chain line in FIG. 3.

[0029] On the other hand, with respect to the inner surface material 12 on the inner circumferential side portion 10b, the non-coated portions 17 at both ends in the width direction of the strip material 15 are easily deformed in cross section without stiffness, while the middle portion in the width direction of the strip material 15 is given stiffness by the hot melt adhesive layer 16 and the cross-sectional deformation is suppressed. For this reason, as shown by the solid line in FIG. 3, the cross-sectional shape of the strip material 15 between the pitches of the core materials 11 is approximately C-shaped or U-shaped, and the middle portion in the width direction of the strip material 15 becomes relatively flat. Thereby, it is possible to suppress the soft heat insulating layer 13 from bulging toward the inner circumferential side.

[0030] Therefore, it is possible to surely suppress the formation of large folds in the inner surface material 12 on the inner circumferential side portion 10b by a simple and inexpensive means, and the inner circumferential surface of the inner circumferential side portion 10b can be held relatively smoothly. Width W of hot melt adhesive layer 16 16 However, by making the effective width W15a of the band material 15 50% to 90%, the soft insulation layer 13 at the inner side portion 10b can be reliably prevented from expanding toward the inner circumference in the duct radial direction, and the inner surface of the inner side portion 10b can be reliably maintained smoothly. As a result, the air flow in the duct can be prevented from becoming turbulent near the inner circumference side portion 10b, and pressure loss can be reduced. According to experiments conducted by the inventors, it was confirmed that by providing the hot melt adhesive layer 16, the pressure loss at the 90° bend portion can be reduced by about 30% to 37% compared to when the hot melt adhesive layer 16 is not provided.

[0031] Next, another embodiment of the present invention will be described. In the following embodiment, the same components as those in the above-described embodiment will be denoted by the same reference numerals in the drawings and the description thereof will be omitted. <Second embodiment (FIG. 6)> As shown in Fig. 6, in an automatic molding machine 20B according to a second embodiment of the present invention, a coating nozzle 33 is disposed on the outer periphery of the inner surface material 12 downstream of the forming section 23 (on the right side in Fig. 4). The coating nozzle 33 faces a middle portion in the width direction of the strip material 15 between the pitches of the core material 11. The longitudinal direction of a slot-shaped discharge port 34 of the coating nozzle 33 is oriented in the width direction of the strip material 15 constituting the inner surface material 12 or in the duct axis direction.

[0032] In the second embodiment, the coating step is performed after the molding step and before the covering step. That is, after the strip material 15 is formed into the spiral cylindrical inner surface material 12 by the molding section 23, a constant width of hot melt adhesive 16a is applied to the middle part of the width direction of the strip material 15 on the inner surface material 12. In this way, a spiral strip-shaped hot melt adhesive layer 16 is formed. The outer periphery of the spiral cylindrical inner surface material 12 thus formed is covered with a soft heat insulating material 13 with a surface sheet 14 .

[0033] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the step of applying the hot melt adhesive 16a may be performed manually by an operator. Even in this case, variations in quality due to the operator's skill level are less likely to occur. The hot melt adhesive layer 16 may be coated on the inner circumferential side surface of the strip material 15, that is, the inner circumferential surface of the inner surface material 12. The flexible duct for air conditioning may have an inner surface material 12 that defines an air conditioning air passage and a core material 11 that keeps the inner surface material 12 in a spiral cylindrical shape, and does not necessarily have a soft heat insulating layer.

Industrial Applicability

[0034] The present invention can be applied to, for example, air conditioning equipment in buildings.

Explanation of Signs

[0035] W 15a Effective width of the strip material W 16 Width of the hot melt adhesive layer 1 Flexible duct for air conditioning 10 Bending part 10a Outer circumferential part 10b Inner circumferential side part 11 Core material 12 Inner surface material 13 Soft heat insulating layer 14 Surface sheet 15 Strip material 16 Hot melt adhesive layer 16a Hot melt adhesive 17 Uncoated part 20, 20B Automatic forming machine 21 Core material line 22 Strip material line 23 Forming part 30 Hot melt adhesive application line 31 Supply source 33 Application nozzle 34 Discharge port

Claims

1. A flexible duct for air conditioning, comprising: a spiral core material; a spiral cylindrical inner surface material made of a non-woven fabric or a resin film strip wound spirally and stretched between the pitches of the core material; and a soft heat insulating layer covering the outer periphery of the core material and the inner surface material, wherein a spiral hot melt adhesive layer is coated on an intermediate portion in the width direction of the outer peripheral side surface of the strip, and the hot melt adhesive layer faces directly without being adhered to the soft heat insulating layer.

2. The flexible duct for air conditioning according to claim 1, wherein the width of the hot melt adhesive layer is 50% to 90% of the effective width of the strip.

3. In a method for manufacturing a flexible duct for air conditioning, comprising: a forming step of winding the core material spirally and winding a strip of non-woven fabric or resin film spirally and stretching it between the pitches of the core material to form a spiral cylindrical inner surface material; and a covering step of covering the outer periphery of the inner surface material with a soft heat insulating layer, before the covering step, a coating step of applying a hot melt adhesive with a constant width to an intermediate portion in the width direction of the outer peripheral side surface of the strip is performed to form a spiral hot melt adhesive layer, and after the hot melt adhesive layer is cured, the covering step is performed so that the hot melt adhesive layer faces directly without being adhered to the soft heat insulating layer.

4. The method for manufacturing a flexible duct for air conditioning according to claim 3, wherein the coating step is performed before the forming step.

5. The method for manufacturing a flexible duct for air conditioning according to claim 3, wherein the coating step is performed after the forming step.

Images