Metal deforming – Tool and/or tool holder – Including flexible or yieldable tool or support
Patent
1995-02-27
1997-11-11
Jones, David
Metal deforming
Tool and/or tool holder
Including flexible or yieldable tool or support
72 75, B21B 2500, B21D 903
Patent
active
056851901
DESCRIPTION:
BRIEF SUMMARY
This invention relates generally to Expanding Mandrels, An Expanding Method and An Expanding Apparatus using an expanding mandrel. It also relates to a Heat Exchanger with heat exchanging tubes which are expanded by disclosed expanding method.
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention mainly relates to an expanding mandrel for fabrication of a cross fin coil for use in a heat exchanger of an air conditioning machine. It also concerns an expanding method and an expanding apparatus both of which employ the expanding mandrel.
2. Background Art
A cross fin coil for use in a heat exchanger of an air conditioning machine is fabricated by piercing a plurality of heat exchanging tubes through a plurality of fins and fixing the tubes to the fins by expanding the tubes.
A mechanical type expanding apparatus is used a lot for fabrication of a cross fin coil. A conventional mechanical type expanding apparatus is shown in FIGS. 22 and 23. Although the conventional expanding apparatus illustrated herein is of the horizontal type, an expanding process is carried out on the same principle in a vertical type expanding apparatus as well.
The conventional, mechanical type expanding apparatus (of horizontal type) comprises a horizontal bed 1; a movable frame 4 which makes back-and-forth motion between a pair of front and rear stationary frames 2, 3 disposed on the bed; and a plurality of mandrels 5, 5 . . . which are horizontally arranged between the stationary frames 2, 3, are connected at their basal ends to the movable frame 4 and are provided at their leading ends with expanding heads.
For expansion of a tube, a cross fin coil W to be expanded is fixed on the bed 1 in front of the stationary frame 2, first, and then the movable frame 4 is moved forwardly. The mandrels 5, 5 . . . are then advanced at a time, passing through the stationary frame 2, so that the expanding heads disposed at the leading ends of the mandrels are forcibly inserted into cooling tubes of the cross fin coil, so as to expand the cooling tubes simultaneously.
This conventional mechanical type expanding apparatus needs marginal spaces for pulling out the mandrels and increases in length. Generally, the conventional type apparatus is required to have a length fourth times as long as the whole length of the cross fin coil. Due to this, this conventional mechanical type expanding apparatus has disadvantage that the apparatus becomes large in size.
Besides, since the mandrels cannot be inserted into non heat exchanging tubes, there is a limitation in that a cross fin coil of L-shaped type or U-shaped type having heat exchanging tubes bent as shown in FIGS. 24 and 25 cannot be processed for expansion. Due to this limitation, in the case of the cross fin coil of the L-shaped type or the U-shaped type, before the cross fin coil undergoes a bending process, the tubes are expanded and fixed to the fins, and then the cross fin coil is bend-processed.
However, with this expansion work, there is a drawback that the fins are subjected to damage at the time of bending. In addition, this work is difficult to apply to a multiple array of coils, because, in the multiple array of coils, inside and outside coils of which curvature radii are different must spaced apart from one another.
For solving these problems, a hydraulic type expanding apparatus has been proposed. The hydraulic type expanding apparatus is practically applied to large-sized cross fin coil having a whole length of more than two meters.
However, where this hydraulic type expanding apparatus is applied to the cross fin coil of the L-shaped type or the U-shaped type, work hardening has developed in the bent portions of the heat exchanging tubes, so that the bent portions are insufficiently expanded. Due to this, the heat exchanging tubes are not sufficiently secured to the fins at their bent portions, resulting in performance reduction of around 5%.
Moreover, since the alternative fluorocarbon is averse to water, more than anything else, it is difficult to introduce the hydra
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Katagami Takuro
Miwa Shigemi
Nakao Noriaki
Ogami Isao
Yamamoto Yoshitaka
Daikin Industries Ltd.
Jones David
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