JP7603299B2 - Inner cover for flexible duct and manufacturing method thereof - Google Patents

Description

This invention relates to the inner casing of a flexible duct, in which a spiral body made of nonwoven fabric or the like is crimped with a fastener to fix it into a cylindrical shape.

Conventionally, flexible ducts made of nonwoven fabric have been used as air conditioning ducts. One such flexible duct is manufactured by overlapping the edges, spirally winding the nonwoven fabric, and fixing it into a cylindrical shape using the crimped parts of the fastening parts, using the manufacturing method shown in Patent Document 1. Flexible ducts manufactured using this manufacturing method have both overlapping edges positioned on the outer surface of the duct, and do not form internal fins, reducing the resistance of the air flowing inside the duct.

JP 2019-049401 A

Air conditioning ducts made of flexible ducts are used by connecting them to air outlets, ducts, chambers, etc. When connecting to existing air outlets, the inside diameter of the existing object and the inside diameter of the air conditioning duct (diameter of the flexible duct) may differ, and in order to connect them, it is necessary to use a joint with ends that correspond to both diameters. If the difference between the two diameters is large, the diameter will fluctuate greatly over a short distance in the flow direction (axial direction of the joint), resulting in large pressure loss at the connection part (joint), and a large, high-output blower will be required. In addition, if a joint with a large diameter difference (diameter fluctuation) is used, it is more likely to cause vibration and noise due to increased air resistance, which is one of the causes of pressure loss.

The objective is to provide an inner casing for a flexible duct that can be reduced in diameter without using a separate component such as a chamber, and a method for manufacturing the same.

In view of the above problems, the present invention provides an inner covering for a flexible duct , which has a fastening portion formed by crimping the overlapping edges of a spirally overlapped strip-shaped body, and is used for a flexible duct formed by winding glass wool around the outer surface of the inner covering which is cylindrical and has a longitudinal direction , and further winding an outer cover around the inner covering,
The inner jacket is characterized in that a reduced diameter portion is formed by bending the retaining portion so as to protrude from the spiral direction toward the longitudinal direction of the inner jacket, which is the axial direction of the spiral .

In addition, it is preferable that the reduced diameter portion formed to protrude in the longitudinal direction of the inner jacket has a convex shape consisting of two protruding sides in the protruding direction and a tip side that connects the two protruding sides and has a predetermined length in the spiral direction of the reduced diameter portion.

The two protruding edges preferably have two first bends on one side that bend around a spiral circle, and two second bends on the other side that form a tip edge from the protruding edge, and each of the two protruding edges preferably has an inclined edge that is inclined toward the center so that the distance between the second bends is shorter than the length between the first bends.

In addition, the manufacturing method of the inner jacket for a flexible duct according to the present invention includes a fastening portion formed by crimping the overlapping edges of a spirally overlapped belt-like body, and a cylindrical inner jacket having a longitudinal direction, and glass wool is wound around the outer surface of the inner jacket, and an outer jacket is further wound around the inner jacket to form the inner jacket for a flexible duct,
A method for reducing the diameter of a cylindrical inner jacket for a flexible duct, comprising the steps of:
an inner cover manufacturing process in which a wire and a steel material are arranged on the edge of the spirally overlapped strip, and the wire and the steel material are crimped together to form a fastening portion , and then a glass wool and an outer cover are wound around the wire and the steel material to form a cylindrical inner cover for a flexible duct before the flexible duct is completed ;
and a reduced diameter portion forming process for forming a convex reduced diameter portion by pressing a pressing tool having a pressing surface of a predetermined width at its tip against the outer surface of the inner housing manufactured in the inner housing manufacturing process while supporting the circular periphery of the fastening portion.

The invention described in claim 1 makes it possible to provide an inner casing for flexible ducts that reduces pressure loss by forming a narrow diameter section by protruding and deforming the fastening section, thereby gradually and gently changing the diameter. Furthermore, it becomes possible to form the narrow diameter section after the inner casing is completed, making it possible to provide an inner casing for flexible ducts that can be individually adapted to the installation situation.

The invention described in claim 2 makes it possible to provide an inner casing for a flexible duct that is unlikely to affect the ventilation inside the duct even if the reduced diameter portion is present, by making the shape of the reduced diameter portion a convex body, so that the tip edge is in the same direction as the spirally formed circular periphery, thereby reducing the pressure loss during airflow.

The invention described in claim 3 makes it possible to provide an inner casing for flexible ducts that is less likely to be damaged by reducing the load applied to the band-shaped body through the formation of a reduced diameter section.

The invention described in claim 4 makes it possible to easily form a reduced diameter section that can reduce the diameter of the inner casing for flexible duct of the present invention. In other words, while it was extremely difficult to reduce the diameter of the duct itself in the past, it is now possible to form the reduced diameter section from the outside after the inner casing is once completed, making it possible to provide reduced diameter ducts easily and in a mass-produced manner.

1 is a side view of an inner cover for a flexible duct according to an embodiment of the present invention. FIG. 2 is an enlarged side view of a portion around a reduced diameter portion, in which an area A in FIG. 1 is enlarged. FIG. 2 is a perspective view of a processing device for manufacturing the reduced diameter portion of the present invention. FIG. 2 is a front view of a processing device for manufacturing a reduced diameter portion of the present invention. FIG. 2 is a perspective view showing a state in which an inner housing is set in the processing device. 5A and 5B are partially enlarged front views showing a state in which a reduced diameter portion is manufactured by a processing device, in which FIG. 5A shows the state before processing and FIG.

The embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment, and various modifications and additions are possible within the scope of the gist of the present invention. In this embodiment, the longitudinal direction of the inner jacket 1 (the axial direction of the spiral) is defined as the longitudinal direction of the inner jacket, and the direction in which the retaining portion 4 spirals around the surface of the inner jacket 1 is defined as the spiral direction. In particular, the spiral direction of the reduced diameter portion 6 is defined as the direction in which the retaining portion 4 was originally spiraling at the position of the reduced diameter portion 6.

The flexible duct inner jacket 1 of the present invention is used as the inner core of a flexible duct used as an air conditioning duct. Although not shown, the completed flexible duct is molded by wrapping glass wool around the outer surface of the flexible duct inner jacket 1 and then wrapping an outer jacket made of an olefin resin around it. As shown in Figure 1, the inner jacket 1 of this embodiment is basically composed of a band 3 wound in a hollow spiral shape and a fastener 4 that secures the edges 5, 5 where the bands 3, 3 overlap.

The strip 3 forms the wall surface of the cylindrical inner cover 1, and is made of a strip of a specified width with a base material of nonwoven fabric, cloth, or paper, which is coated with a synthetic resin. The strip 3 is wound spirally with the edges 5, 5 overlapping each other to form a cylindrical shape. The strip 3 is made of a film or sheet, and the cross section of the wound cylinder is circular.

The overlapping edges 5, 5 of the strip 3 are held by the fastener 4 and fixed into a cylindrical shape. The fastener 4 is made of a steel wire-like core material (not shown) that contacts the outer periphery of the strip 3 and is wound helically around the edges 5, 5, and a metal sheet. The wire (core material) is placed along the edges 5, 5, and the metal sheet is overlapped on the inside. The edges 5, 5 are sandwiched and prevented from slipping out by the core material while the core material is bent inward to form a C-shape, and both edges 5, 5 are fastened and fixed through a crimping process.

The inner jacket 1 is formed by folding back the edges 5, 5 of the band 3 to the outer side of the duct and overlapping them with the outer (outer) edge 5 in the crimping process of the fastening portion 4, so that both edges 5, 5 are positioned on the outer side of the inner jacket 1. The part where the two edges 5, 5 are overlapped and protrude slightly to the outer side is called a fin. In another embodiment, the crimping process may be performed so that the edges 5, 5 (fins) protrude to the inside of the inner jacket 1.

As shown in FIG. 1, the retaining portion 4 has one or more reduced diameter portions 6, 6 formed on the outer periphery at a predetermined interval in the spiral direction. The reduced diameter portions 6 are formed by bending the retaining portion 4 that has been crimped (subjected to a crimping process) so as to protrude convexly toward the inner casing longitudinal direction, which is the longitudinal direction of the inner casing 1. In this embodiment, the direction in which the reduced diameter portions protrude toward the inner casing longitudinal direction to become convex is aligned with the protruding direction of the edge portions 5, 5 (fins) located outward from the retaining portion 4. This alignment reduces pressure loss and makes the inner casing less likely to break. Being convex in the axial direction of this spiral means that the protruding direction of the inner casing 1, which has a circular shape with a longitudinal direction, is aligned with the longitudinal direction.

By forming a portion of the spiral fastening portion 4 with a reduced diameter portion 6 so that it is convex in one direction, the band-shaped body 3 that is crimped and held by the fastening portion 4 is also deformed. In this deformation, the circumference of the inner jacket 1 shrinks and the diameter is reduced. By arranging multiple identical reduced diameter portions 6 in the spiral direction, the inner jacket 1 is reduced in diameter according to the number of arranged portions, so by gradually narrowing the spacing (number) between the arranged portions, it becomes a spiral shape with a gradually reduced diameter. And by arranging the reduced diameter portions 6 at equal intervals, it becomes a spiral shape that maintains the reduced diameter dimension.

In this embodiment, the convex protruding direction of the reduced diameter portion 6 is the same as the outward protruding direction of the edges 5, 5 (fins), and the convex tip of the reduced diameter portion 6 is linear (tip edge 8, described below) so as to follow the spiral direction of the reduced diameter portion.

To explain the specific form of the reduced diameter portion 6, FIG. 2 shows a partially enlarged view of only the reduced diameter portion 6. The retaining portion 4 has a circular periphery 4a that forms a spiral circumference of the duct, a pair of first bent portions 9, 9 that bend this circular periphery 4a, a pair of protruding edges 7, 7 that extend from the first bent portions 9, 9 in the longitudinal direction of the inner casing, a pair of second bent portions 10, 10 that are bent so as to face each other from the tip portions of the protruding edges 7, 7, and a tip edge 8 that extends in a straight line shape along the spiral from both second bent portions 10, 10 and connects both protruding edges 7, 7. The tip edge 8 has a predetermined length that extends in the spiral direction of the reduced diameter portion. Note that the protruding direction of the reduced diameter portion 6 is formed in the longitudinal direction of the inner casing, and the tip edge 8 is formed in the spiral direction of the reduced diameter portion 6, and this includes a predetermined error, etc., and does not mean that the directions are strictly the same.

The protruding edges 7, 7 are linear and extend at a slight inward angle from the longitudinal direction of the inner sheath, and each of the protruding edges 6, 6 on both sides that make up one reduced diameter section 6 is formed as an inclined edge that slopes toward the center. The protruding edges 7, 7 have a length dimension of about 20 mm toward the tip edge 8. The length dimension of the tip edge 8 is about 10 mm. The protruding length of the protruding edges 7, 7 is about one-quarter of the pitch of the spiral (see Figure 1).

The protruding sides 7, 7 are inclined toward each other toward the center so that the distance X2 between the two second bent portions 10, 10 is shorter than the distance X1 between the two first bent portions 9, 9. In this manner, the reduced diameter portion 6 in this embodiment is formed in a trapezoidal shape. Note that, in other embodiments, the protruding sides 7, 7 may have a shape in which the tip side 8 is curved from the tip side, or the first bent portions 9, 9 and the second bent portions 10, 10 may be curved relatively greatly.

The protruding edges 7, 7 are inclined toward each other toward the center, which makes it difficult for the fins formed on the edges 5, 5 by molding the reduced diameter portion 6 to be pulled in or come off the crimped fasteners. Also, when air is passed through the duct, the bent portion is not bent at a right angle to prevent pressure from concentrating in one area.

Next, the processing device 20 that forms the reduced diameter portion 6 in the inner housing 1 will be described with reference to the drawings.

As shown in FIG. 3, the processing device 20 is composed of a holding table 21 that holds the retaining portion 4, a pressing tool 22 made of a long rod plate that rotates by the principle of a lever to appear and disappear from the holding table 21, and a driving unit 23 that rotates the pressing tool 22. The processing device 20 presses a part of the retaining portion 4 held on the holding table 21 with the pressing tool 22, performs bending processing to form a reduced diameter portion 6, and reduces the diameter of the inner jacket 1. The driving unit 23 is a well-known driving means, and in this embodiment is composed of an air piston, but is not particularly limited and may be a hydraulic piston, a motor-driven crank, or the like.

The pressing tool 22 has one end in the longitudinal direction connected to the drive unit 23, a pressing part 24 protruding downward at the other end, and a support part 26 supported by a support shaft 25 that protrudes downward at the middle part in the longitudinal direction and serves as the fulcrum of the lever, forming an F-shape. The pressing part 24 has a pressing surface at its tip that has a predetermined length in the width direction, and can be moved up and down by the drive unit 23 at the other end.

The holding table 21 is made up of an upper plate 27 and a lower plate 28 that are parallel to each other, and the plate surface of the upper plate 27 is arranged perpendicular to the moving direction of the pressing part 24. As shown in FIG. 4, the holding table 21 has a guide slit 30 formed between the upper and lower plates 27, 28 and opening to the front and in the width direction of the lower plate 28, and a processing groove 31 formed in the center of the width direction of the lower plate 28 and opening to the front and above and below perpendicular to the plate surface.

As shown in Figures 5 and 6, the guide slit 30 has a vertical dimension that is approximately the same as the length of the fastening portion 4 plus the thickness of the strip 3. The guide slit 30 supports the fastening portion 4 in the processing position from above and below by inserting the fastening portion 4 from the front side.

The machined groove 31 is formed perpendicular to the guide slit 30, penetrating the upper plate 27 and the lower plate 28, allowing the pressing part 24 to move up and down. The machined groove 31 consists of an upper part 33 formed on the upper plate 27 side and a lower part 34 formed on the lower plate 28 side. The width dimension of the upper part 33 is approximately the same as or slightly longer than the width dimension of the pressing part 24, allowing the pressing part 24 to move freely without contacting the upper part 33.

The lower portion 34 has a width dimension greater than that of the upper portion 33, and has a wide gap S between it and both plate surfaces of the moving pressing portion 24 (on both the left and right sides) (see FIG. 6). The width dimensions of the left and right gaps S are approximately the same as the vertical dimensions of the guide slits 30, allowing the retaining portion 4 and the band-shaped body 3 (reduced diameter portion 6) to be accommodated during processing.

When the pressing part 24 is in an unloaded state, it is located at the upper part 33 of the machining groove 31, and when the pressing tool 22 is rotated by the driving part 23, it crosses the guide slit 30, and when it rotates further, it descends to the lower part 34. When the pressing part 24 is in a fully loaded state after rotating the most, its lower end is located lower than the top surface of the lower plate 28.

Next, a method for manufacturing the inner jacket 1 of this embodiment will be described. First, a general inner jacket 1 is manufactured. The inner jacket 1 is manufactured by spirally winding the strips 3, 3 while overlapping the edges 5, 5 using a dedicated manufacturing machine called a mandrel. At this time, a wire is placed along one surface of the overlapped edges 5, 5, and a metal sheet that will become the outer surface of the fastening portion 4 is placed along the other surface. The metal sheet is then bent to narrow the width, and is shaped and crimped to embrace the edges 5, 5 and the wire. In this way, a normal cylindrical inner jacket 1 is completed.

The processing device 20 described above is used to form the reduced diameter portion 6 of the inner jacket 1. First, as shown in FIG. 5, the fastening portion 4 (circular periphery 4a) is inserted into the guide slit 30 of the processing device 20. In this way, the fastening portion 4 of the inner jacket 1 protrudes slightly from the outer surface of the wrapped bands 3, 3, and the band 3 is made of a relatively soft material, so it can be inserted into the guide slit 30.

As shown in Figures 6(a) and (b), by inserting the retaining portion 4 into the guide slit 30, a reduced diameter portion 6 is formed at the portion crossing the machining groove 31, and the guide slit insertion portion other than the machining groove 31 (circular periphery 4a) is held by the upper plate 27 and the lower plate 28. In this state, by rotating the pressing tool 22 with the driving unit 23 to lower the pressing portion 24, the circular periphery 4a is bent so that first bent portions 9, 9 and second bent portions 10, 10 are formed, and a trapezoidal reduced diameter portion 6 having protruding sides 7, 7 and a tip side 8 can be formed.

A reduced-diameter flexible duct can be manufactured by wrapping glass wool and an outer skin around the reduced-diameter inner casing 1 manufactured in this way. Note that the above manufacturing method allows the reduced-diameter sections 6, 6 to be manufactured from the outside of the inner casing 1 as appropriate, so it is also possible to manufacture an inner casing 1 that is first reduced in diameter and then expanded in diameter. In this case, it is also possible to manufacture an inner casing with the maximum diameter, and then form multiple sections with gradually reduced diameters, making it possible to manufacture a flexible duct with a complex change in diameter.

In addition, each of the reduced diameter portions 6, 6 in this embodiment reduces the inner jacket 1 by approximately 19.5 mm in the circumferential direction. The diameter (center diameter) of the inner jacket 1 is often manufactured in increments of 50 mm, and there are types of 150, 200, 250, 300, and 350. For example, the spiral length (inner diameter circumference) of the retaining portion 4 with a center diameter of 150 mm is 502.4 mm, and the spiral length (target circumference) of one turn when the center diameter after reduction is to be 100 mm is 345.4 mm. The difference is 157 mm, and if eight reduced diameter portions 6, 6 that reduce 19.5 mm are formed, a reduction of 50 mm is possible. When other types were calculated, as shown in Table 1 below, if eight reduced diameter portions 6, 6 that reduce 19.5 mm are formed, a reduction of 50 mm is possible. This makes it possible to provide an inner casing 1 for flexible ducts that can achieve a desired diameter reduction using a simple configuration and method.

1...Inner cover for flexible duct, 3...Strip, 4...Fastening portion, 4a...Circular periphery, 5...Edge, 6...Reduced diameter portion, 7...Protruding edge, 8...Tip edge, 9...First bend, 10...Second bend.

Claims (4)

The inner covering is used for a flexible duct, which is formed by winding glass wool around the outer surface of a cylindrical inner covering having a longitudinal direction , and further winding an outer covering around the inner covering, and has a fastening portion formed by crimping the overlapping edges of a spirally overlapping strip,
The inner casing for a flexible duct is characterized in that the inner casing has a reduced diameter portion formed by bending the fastening portion so as to protrude from the spiral direction toward the longitudinal direction of the inner casing, which is the axial direction of the spiral . The flexible duct inner jacket according to claim 1, characterized in that the reduced diameter section formed to protrude in the longitudinal direction of the inner jacket has a convex shape consisting of two protruding sides in the protruding direction and a tip side that connects the two protruding sides and has a predetermined length in the spiral direction of the reduced diameter section. The two protruding sides have two first bending portions that bend around a spiral circle on one side, and two second bending portions that form a tip side from the protruding side on the other side,
The inner covering for a flexible duct as described in claim 2, characterized in that the two protruding sides each consist of an inclined side that inclines toward the center so that the distance between the second bent portions is shorter than the length between the first bent portions. The inner covering is used for a flexible duct, which is formed by winding glass wool around the outer surface of a cylindrical inner covering having a longitudinal direction, and further winding an outer covering around the inner covering, and has a fastening portion formed by crimping the overlapping edges of a spirally overlapping strip,
A method for reducing the diameter of a cylindrical inner jacket for a flexible duct, comprising the steps of:
an inner cover manufacturing process in which a wire and a steel material are arranged on the edge of the spirally overlapped strip, and the wire and the steel material are crimped together to form a fastening portion , and then a glass wool and an outer cover are wound around the wire and the steel material to form a cylindrical inner cover for a flexible duct before the flexible duct is completed ;
a reduced diameter portion forming process for forming a convex reduced diameter portion by pressing a pressing tool having a pressing surface of a predetermined width at its tip against the outer surface of the inner covering manufactured in the inner covering manufacturing process while supporting the circular periphery of the fastening portion.

Images