JPS61144214A - Formation of fin of cross-fin tube and its device - Google Patents

Abstract

PURPOSE:To manufacture easily and inexpensively a well-shaped cross-fin tube, by drawing a raw tube while passing it through a uniform-width gap between a plug and a die, contoured respectively into male and female star-shaped cross sections having trapezoidal radial-projections, before passing it through a die used for restricting and pressing the tips of the projections and their neighborhoods. CONSTITUTION:A raw circular tube is passed, as if it were squeezed, through a uniform-width gap 3 between a die 1 and a plug 2, contoured respectively into male and female star-shaped cross sections having trapezoidal radial- projections 4, to draw the raw tube into a raw tube 6 having the same contour. The tube 6 is passed through a die 9, having grooves 8 arranged at equal intervals for restricting the tips 7 of projections 4 and their neighborhoods, to reduce its outer diameter, thereby obtaining a shape having mutually approached roots 11 of projections 4. Then a well-shaped cross-fin tube is obtained by fitly inserting this well-shaped cross-fin tube 10, manufactured easily and inexpensively, into a circumscribing tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for forming fins of a cross-fin tube used in a heat exchanger, etc., and particularly relates to a method for forming fins of a cross-fin tube used in a heat exchanger, etc. The present invention relates to a fin molding method and apparatus.

[Prior art (1)] Conventionally, as shown in FIG. 8, the method and apparatus for forming the fins of a loss fin tube include the indentation method and apparatus using a Turk's head, or the roll processing method and apparatus. That device exists. This conventional processing method and its apparatus are both a processing method and its apparatus in which a tube is crushed with forming rolls to form fins.

[Problem to be solved by the invention (1)] However, in all of these conventional methods of forming fins for cross-fin tubes, the fins are formed by crushing the tube with forming rolls, so there are many problems. In the case of processing to form striped fins, there is a problem in that the processing equipment is large-scale and the manufacturing cost of the fins is high. There was also the problem that the workability of fin processing was extremely poor.

[Prior art (2)] In addition, as shown in Fig. 6, a cross-fin tube fin processing method and its apparatus by drawing are performed using dies and plugs that match the shape of the finished fin, as in normal drawing processing. was being attempted.

Furthermore, a dough tube whose cross-sectional shape has a star-shaped outline is placed in the seventh
Attempts were also made to draw the pipe using the pipe drawing die shown in the figure.

[Problems to be Solved by the Invention (2)] In addition, there was a problem in that drawing with a die and plug that matched the shape of the finished fin described above required too much processing, making drawing impossible.

Furthermore, when the pipe is drawn with a pipe drawing die, the shape of the fins becomes non-uniform on the left and right sides, resulting in a reduction in thermal efficiency.

[Means for solving problems]

The present invention provides, at low cost, the fins of a cross-fin tube having uniform fins with improved thermal efficiency using a drawing method and an apparatus therefor, in order to eliminate the problems in the conventional products described above.

Therefore, the gap 3 formed between the die 1 and the plug 2 in FIG. The raw material tube 5 shown in FIG. The dough tube 6 shown in FIG. 4 is formed, and then, as shown in FIG. The dough tube 6 is passed through the die 9 formed on the inner periphery and pulled out, so that the shape of the cross section shown in FIG.
In this embodiment, a fin 10 is formed in which the hollow horizontal peaks 4 are arranged radially.

In addition, the forming device has a gap 3 formed between the die 1 and the plug 2 for drawing out the dough tube 6, whose cross section has a star-shaped outline, and which faces outward from the star-shaped outline. The die 1 has a trapezoidal tip 4, and the trapezoidal tip 4 is used to pull out the plug 2 and fins.
The die 9 has an axial groove 8 formed on its inner periphery to which the tip 7 and the vicinity thereof engage.

[For production]

According to the above-mentioned means of the invention, as shown in FIG. 2, there is a gap 3 between the die 1 and the plug 2, which has a star-shaped cross section and a trapezoidal shape with the outwardly facing apex 4. When drawing is performed through the raw material pipe 5 shown in FIG. 5, the raw material pipe 5 has a star-shaped cross section as shown in FIG. 4, and the apex 4 faces outward from the star-shaped outline. is formed into a trapezoidal dough tube 6.

Next, in FIG. 1, a die 9 having an axial groove 8 formed on the inner periphery that engages the tip 7 of the trapezoidal apex 4 of the dough tube 6 and its vicinity is inserted into the dough tube. Perform step 6. At this time, the tip 7 and the vicinity of the tip of the trapezoidal tip 4 of the dough tube 6 are engaged with the groove 8 of the die 9 and the trapezoid tip 4 is pulled out, so that the trapezoid tip does not fall down and the third
As shown in the figure, the rear end 11 of the trapezoidal apex 4 is pressed into the center, and is formed into a hollow fin 10 with a uniform cross section whose width a increases toward the outside. Shape of Fin [Example] The present invention will be explained below with reference to examples shown in the drawings.

FIG. 2 is a cross-sectional view of a die 1 and a plug 2 used for drawing a dough tube in the method and apparatus for forming fins of a cross-fin tube according to the present invention. A gap 3 having a star-shaped cross section is provided. The apex 4 facing outward from the star-shaped outline is formed into a trapezoid. When drawing is performed by passing the raw material pipe 5 shown in FIG. A dough tube 6 is formed into a shape similar to the above shape and has a star-shaped cross section, and a tip 4 facing outward from the star-shaped profile is formed into a trapezoid. Next, FIG. 1 is a cross-sectional view of a die 9 used for drawing out the fins, and shows an axial groove 8 that engages the tip 7 and the vicinity of the tip 7 of the trapezoidal tip 4 of the dough tube 6. It is formed on the inner periphery.

The trapezoidal tip 4 of the dough tube 6 is inserted into the groove 8 of this die 9.
When the fabric tube 6 is engaged and pulled out, the trapezoidal tip 4 of the trapezoidal tip 4 is pushed into the center of the fabric tube 6, as shown in FIG. The apex 4 is formed into a hollow-shaped fin 10 of uniform cross section with %Ba increasing toward the outside.

[Effects of the Invention] As explained above, according to the method and device for forming fins of a cross-fin tube according to the present invention, it is possible to easily provide fins with improved thermal efficiency for use in cross-fin tubes at a low price. It became possible.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, and FIG.
FIGS. 7 and 8 show conventional examples. FIG. 1 is a cross-sectional view of a die used for drawing the fins, FIG. 2 is a cross-sectional view of the die and plug used for drawing the fabric tube, and FIG. 3 is a cross-sectional view of the fins. Figure 4 is a cross-sectional view of the dough tube, Figure 5 is a cross-sectional view of the raw material tube, Figure 6 is a cross-sectional view of a die that matches the shape of the finished fin, and Figure 7 is a cross-sectional view of a die for drawing the tube. FIG. 8 is a cross-sectional view of the cross fin cheep. 1: die, 2 nib lugs, 3: gap, 4: apex. 5: Raw material pipe, 6: Dough pipe, 7: Tip, 8: Groove. 9: Dice, 10: Fin, 11: Rear end 30th
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Claims (2)

[Claims] (1) A gap formed between the die and the plug, the die having a star-shaped cross section and a trapezoidal apex facing outward from the star-shaped profile. and pull out the raw material pipe through the gap between the plug and
A dough tube whose cross-sectional shape is formed to the cross-sectional shape of the gap between the die and the plug is formed, and then the tip of the trapezoidal apex of the dough tube and its vicinity are engaged. The fabric tube is passed through a die having an axial groove formed on the inner periphery and then drawn to form a hollow fin whose cross-sectional shape increases in width toward the outside and where the cusps are arranged radially. A method for forming fins of a cross-fin tube characterized by performing the following steps. (2) A gap formed between the die and the plug, the die having a star-shaped cross section and a trapezoidal apex facing outward from the star-shaped profile. and a plug, and a shaft engaged with the tip and vicinity of the trapezoidal apex of a fabric tube that is drawn through the die and the plug and whose cross-sectional shape is formed to have a cross-sectional shape of the gap between the die and the plug. A fin forming device for a cross-fin tube, comprising: a die having directional grooves formed on the inner periphery thereof.