Wire condenser element bending method and wire condenser element bending apparatus

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wire condenser element bending method of forming a scroll wire condenser for an air conditioning system or the like by scrolling a wire condenser element, and a wire condenser element bending apparatus for carrying out the wire condenser element bending method.

2. Description of the Related Art

A wire condenser element of this type having a large heat-transfer area is formed by bending a thin-wall, small-diameter metal tube of a metal having a high thermal conductivity and good workability, such as copper, in a plurality of parallel segments, and extending iron wires across the plurality of segments of the metal tube to increase heat radiating rate and to reinforce the wire condenser element.

FIG.

5

(

a

) shows a general wire condenser element

2

formed by bending a metal tube

3

in a plurality of segments and extending iron wires

4

across the plurality of segments of the metal tube

3

, and FIG.

5

(

b

) shows a scroll wire condenser

1

formed by processing the wire condenser element

2

. Various wire condensers as a component of a condenser unit are available. The wire condenser

1

shown in FIG.

5

(

b

) is formed by scrolling the wire condenser element

2

shown in FIG.

5

(

a

). Wire condensers similar to the wire condenser

1

shown in FIG.

5

(

b

) has compact construction and a large heat-transfer and hence such wire condensers are used prevalently.

A conventional scroll wire condenser forming process illustrated in FIGS.

6

(

a

) and

6

(

b

) scrolls the wire condenser element

2

by using a roller to form the scroll wire condenser

1

. As shown in FIG.

6

(

a

), the wire condenser element

2

is fed longitudinally. The wire condenser element

2

is pressed against a rotating bending roller

5

by a rotating pressure roller

6

to roll the wire condenser element

2

around the bending roller

5

. The innermost layer of the wire condenser element

2

is wound around the bending roller

5

and hence any particular problem does not arise. When winding the second innermost layer and other outer layers, a separator

7

, i.e., a sheet, must be bent and wound together with the wire condenser element

2

around the bending roller

5

to secure a clearance between the layers of the wire condenser element

2

as shown in FIG.

6

(

b

). After thus winding the wire condenser element

2

together with the separator

7

in a scroll as shown in FIG.

6

(

b

), the separator

7

is removed from the scroll to complete the wire condenser

1

.

Thus, the separator

7

is indispensable to the conventional scroll wire condenser forming process to secure a clearance between the adjacent layers of the wire condenser element

2

. Generally, the separator

7

is a flexible sheet, such as a corrugated cardboard or a rubber sheet. The separator

7

is used repeatedly and hence must have strength high enough to withstand repetitive use. However, corrugated board and the rubber sheet are unsatisfactory in durability and are damaged and broken in a short service time. Although separators of various materials have been tested and proposed, any optimum separators satisfactory in durability have not been available up to the present.

Work for removing the separator from the scroll wire condenser is not suitable for automation and the separator is removed by manual work, which is an impediment to the improvement of manufacturing efficiency.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to solve problems in the conventional techniques and to provide a wire condenser element bending method not requiring any separator and capable of forming a scroll wire condenser at a high productivity.

Another object of the present invention is to provide a wire condenser element bending apparatus for carrying the wire condenser element bending method.

The present invention provides a bending method of bending wire condenser elements each formed by bending a small-diameter metal tube in a plurality of parallel segments and extending metal wires across the segments of the metal tube around a bending roller to form scroll wire condensers, comprising the steps of: holding inner edge parts of two or more wire condenser elements respectively by holding devices arranged at equal angular intervals on an outer circumference of the bending roller; winding the two or more wire condenser elements around the bending roller by pressing the wire condenser elements against the bending roller with pressure rollers while the bending roller is rotated so that respective layers of the wire condenser elements are superposed sequentially to form two or more scroll wire condensers, using each wire condenser element as a separator for separating layers of the adjacent other wire condenser element or elements.

Thus, the layers of the wire condenser elements serve as separators for separating the layers of adjacent other wire condenser elements.

The present invention provides a wire condenser element bending apparatus for bending a plurality of wire condenser elements each formed by bending a small-diameter metal tube in a plurality of parallel segments and extending metal wires across the segments of the metal tube around a bending roller to form a plurality of scroll wire condensers, said bending apparatus comprising: a bending roller provided with holding devices arranged at equal angular intervals on its outer circumference to hold inner edge parts of the plurality of wire condenser elements detachably on the outer circumference of the bending roller; a driving unit for driving the bending roller for rotation; and pressing mechanisms including pressure rollers for pressing the wire condenser elements against the bending roller.

According to the present invention, the layers of the plurality of wire condenser elements serve as separators for separating the adjacent layers of the other wire condenser elements. Thus, the present invention does not need any separator and is capable of simultaneously forming a plurality of scroll wire condensers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects features and advantages of the present invention will become more apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1

is a schematic side elevation of a wire condenser element bending apparatus in a preferred embodiment according to the present invention for carrying out a wire condenser element bending method according to the present invention;

FIG. 2

is a perspective view of a bending roller included in the wire condenser element bending apparatus shown in

FIG. 1

;

FIG. 3

is a cross-sectional view of the bending roller shown in

FIG. 2

;

FIGS.

4

(

a

) and

4

(

b

) are sectional views of assistance in explaining the wire condenser element bending method according to the present invention;

FIGS.

5

(

a

) and

5

(

b

) are a plan view of a wire condenser element and a perspective view of a scroll wire condenser, respectively; and

FIGS.

6

(

a

) and

6

(

b

) are views of assistance in explaining a conventional scroll wire condenser forming process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1

shows a wire condenser element bending apparatus in a preferred embodiment according to the present invention capable of simultaneously scrolling two wire condenser elements

2

A and

28

as shown in FIGS.

4

(

a

) and

4

(

b

). Referring to

FIG. 1

, a column

11

is set upright on a base

10

, and a bending roller

12

is supported with its axis horizontally extended on the column

11

. Work feed tables

13

a

and

13

b

respectively for supporting the wire condenser elements

2

A and

2

B thereon are disposed on the left and the right side, as viewed in

FIG. 1

, of the bending roller

12

at different levels, respectively. The difference in height between the upper surfaces of the work feed tables

13

a

and

13

b

is, for example, substantially equal to the diameter of the bending roller

12

. Lower pressure rollers

14

are disposed directly below the bending roller

12

, and upper pressure rollers

15

are disposed directly above the bending roller

12

. The pressure rollers

14

and

15

are driven for vertical movement by pneumatic cylinder actuators

16

and

17

, respectively. The pneumatic cylinder actuator

17

is held on a horizontal crossbeam

18

joined to an upper part of the column

11

. The lower pressure rollers

14

and the lower pneumatic cylinder actuator

16

, and the upper pressure rollers

15

and the upper pneumatic cylinder actuator

17

form lower and upper pressing mechanism, respectively. The wire condenser element

2

A is fed from left to right on the work feed table

13

a

substantially tangentially to the bending roller

12

. The wire condenser element

28

is fed from right to left on the work feed table

13

b

substantially tangentially to the bending roller

12

. A motor

19

is mounted on the base

10

to drive the bending roller

12

for rotation. The rotation of the output shaft of the motor

19

is transmitted through a chain

20

and a sprocket

21

at a reduced rotating speed to the bending roller

12

.

Referring to

FIGS. 2 and 3

, the bending roller

12

has a cylindrical body

22

, and semicylindrical members

24

a

and

24

b

. The semicylindrical members

24

a

and

24

b

are attached to the circumference of the cylindrical body

22

so as to define straight grooves

25

a

and

25

b

parallel to the axis of the bending roller

12

between the edges thereof. The straight grooves

25

a

and

25

b

are formed diametrically opposite to each other with respect to the axis of the bending roller

12

. A plurality of holding pins

27

are arranged at predetermined intervals in parallel to the axis of the bending roller

12

in the straight grooves

25

a

and

25

b

. The holding pins

27

are set in pin-holding bars

31

. The pin-holding bars

31

are attached detachably to the inner circumference of the bending roller

12

. Each of the pin-holding bars

31

is fastened to the inner circumference of the bending roller

12

with two bolts

32

. The two pin-holding bars

31

are used to hold inner edge parts of the wire condenser elements

2

A and

2

B on the bending roller

12

. The bolts

32

are unfastened to remove the pin-holding bars

32

holding the holding pins

27

from the bending roller

12

. The holding pins

27

are engaged in U-shaped bends in the metal tubes forming the wire condenser elements

2

A and

2

B to hold the inner edge parts of the wire condenser elements

2

A and

2

B detachably on the bending roller

12

.

A wire condenser element bending method to be carried out by the wire condenser element bending apparatus thus constructed will be described hereinafter. Referring to FIGS.

4

(

a

) and

4

(

b

), the wire condenser elements

2

A and

2

B are placed on the work feed tables

13

a

and

13

B, respectively. The bending roller

12

is held with the straight groove

25

a

, in which the inner edge part of the wire condenser element

2

A is placed, located at a top position and the straight groove

25

b

in which the inner edge part of the wire condenser element

2

B is placed located at a bottom position as shown in FIG.

4

(

a

). Then, the U-shaped bends in the metal tubes of the wire condenser elements

2

A and

2

B are put on the holding pins

27

as shown in

FIG. 2

to hold the inner edge parts of the wire condenser elements

2

A and

2

B at the diametrically opposite positions on the bending roller

12

.

Then, the pneumatic cylinder actuators

16

and

17

are actuated to press the wire condenser elements

2

B and

2

A against the bending roller

12

with the lower pressure rollers

14

and the upper pressure rollers

15

, respectively. The pressure rollers

14

and

15

are thus kept pressed against the wire condenser elements

2

B and

2

A by the pneumatic cylinder actuators

16

and

17

, respectively. Then, the motor

19

is actuated to rotate the bending roller

12

slowly to wind the wire condenser elements

2

A and

2

B around the bending roller

12

. During the initial rotation of the bending roller

12

through an angle of 180°, the wire condenser elements

2

A and

2

B are bent so as to conform to the outer surfaces of the semicylindrical members

24

a

and

24

b,

respectively. After the bending roller

12

has been turned through an angle of 180°, the wire condenser element

2

A is wound on layers of the wire condenser element

2

B, and the wire condenser element

2

B is wound on layers of the wire condenser element

2

A. Thus, the layers of the wire condenser element

2

A serve as a separator for a scroll wire condenser formed by rolling the wire condenser element

2

B, and those of the wire condenser element

2

B serve as a separator for a scroll wire condenser formed by rolling the wire condenser element

2

A. Thus, two scroll wire condensers are formed simultaneously by simultaneously winding the wire condenser elements

2

A and

2

B.

After the scroll wire condensers have been formed by winding the wire condenser elements

2

A and

2

B around the bending roller

12

, the pneumatic cylinder actuators

16

and

17

are operated to separate the presser rollers

14

and

15

from the wire condenser elements

2

B and

2

A. Then, the bolts

32

are unfastened and the pin-holding bars

31

holding the holding pins

27

are removed from the bending roller

12

. Then the scroll wire condensers are removed from the bending roller

12

and are separated. Since the wire condenser elements

2

A and

2

B are flexible, the scroll wire condensers can be easily separated.

Although the invention has been described as applied to the wire condenser element bending apparatus capable of simultaneously forming two scroll wire condensers, the present invention is applicable to a wire condenser element bending apparatus capable of simultaneously forming three or more scroll wire condensers. When the present invention is applied to a wire condenser element bending apparatus capable of simultaneously forming three scroll wire condensers, three straight grooves parallel to the axis of the bending roller

12

are formed on the outer circumference of the bending roller at angular intervals of 120°, inner edge parts of three wire condenser elements are held detachably by holding members disposed in the three straight grooves, and the three wire condenser elements are bent with three sets of pressure rollers to wind the three wire condenser elements around the bending roller

12

.

The bending roller

12

may be a tubular roller, a solid roller or a polygonal roller.

Although the invention has been described in its preferred embodiments with a certain degree of particularity, obviously many changes and variations are possible therein. It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit thereof.