Single vapor condensation soldering facility

A condensation soldering facility (10) comprised of a housing (12) having a divider member (22) therein which separates the housing into a drying chamber (24) in an upper section and a soldering chamber (26) in a lower section. A transfer member (76) is pivotably mounted within the drying chamber (24) to receive articles (112--112) to be soldered through an access door (71) in the top of the drying chamber (24) and arcuately transfer the articles through an access door (44) in the divider member (22) to solder the articles in the soldering chamber (26).

TECHNICAL FIELD 
The instant invention relates to a condensation heating system. In 
particular, the invention is directed to a single vapor condensation 
heating system and techniques for transferring articles therein. 
BACKGROUND OF THE INVENTION 
In the early 1970's the first commercial system for condensing hot 
saturated vapor on articles for the purposes of soldering, brazing, 
fusing, etc., articles was developed. That system is described in detail 
in U.S. Pat. No. Re. 30,399 which issued on Sept. 9, 1980 to R. C. Pfahl 
and H. H. Ammann assigned to Western Electric Company, Inc. and Bell 
Telephone Laboratories, Inc., and is hereby incorporated by reference 
herein. That patent discloses an article to be soldered, fused or brazed 
being placed in a vessel containing a body of hot saturated vapor. The 
vapor is generated by continuously boiling a heat transfer liquid having 
selected properties including a boiling point at least equal to and 
preferably above the temperature of the soldering, fusing or brazing 
operation to be performed. The vapor condenses on the article and gives up 
its latent heat of vaporization thereto to heat the article to the 
temperature required for the particular operation. This technique has 
found wide acceptance in the industry and has substantially advanced the 
art of soldering, brazing and fusing. 
The Pfahl et al. process was improved to substantially reduce losses of the 
hot saturated vapor of the relatively expensive heat transfer (primary) 
liquid by a technique disclosed in U.S. Pat. No. 3,904,102 to T. Y. Chu et 
al., which issued Sept. 9, 1975 and is assigned to the instant assignee. 
In Chu et al. a blanket of secondary vapor, from a relatively inexpensive 
liquid, having a density intermediate that of the relatively expensive 
primary heat transfer vapor and the atmosphere, floats on the body of 
primary vapor in order to reduce the losses thereof from a condensation 
heating vessel. 
The article on which the soldering, fusing or brazing operation is to be 
performed is passed through the body of secondary vapor into the body of 
primary vapor in the vessel. The primary vapor condenses on the article 
and the latent heat of vaporization of the condensing primary vapor heats 
the article to the temperature required for the soldering, fusing or 
brazing operation. After completion of the operation, the article is 
withdrawn from the body of primary vapor, through the blanketing body of 
secondary vapor, out of the vessel and into the atmosphere where it is 
cooled to ambient temperature. As the article moves out of the vessel, 
vapor is also dragged out and lost to the atmosphere. Most of the vapor is 
secondary, however, some is the relatively expensive primary vapor. 
One technique designed to lessen such vapor losses is described in U.S. 
Pat. No. 4,264,299 which issued on Apr. 28, 1981 to H. H. Ammann et al., 
which is incorporated herein by reference. That patent discloses a 
condensation heating facility having a primary vapor chamber with a drying 
chamber located thereabove. The drying chamber has first and second doors 
in the top and bottom portions thereof, respectively. Articles to be 
soldered are conveyed into the drying chamber through the first door and 
then into the primary vapor chamber, through the second door, where the 
soldering, fusing or brazing operation takes place. The articles are then 
removed to the drying chamber, the first and second doors are closed, and 
drying apparatus activated to remove and filter out any primary vapor 
therein. The first door is then opened and the dry, soldered articles 
removed from the facility. 
The Ammann et al. patent has been found effective for soldering articles in 
a closed, single vapor condensation heating facility which substantially 
reduces loss of the expensive primary vapor to the atmosphere. However, 
the various conveying mechanisms required to transport articles through 
the facility are complex. Therefore, the drying chamber cannot be 
completely sealed during the drying operation. Additionally, the conveying 
mechanisms passing through the facility substantially increase the size of 
the machine because of the horizontal and vertical movement of parts 
required. 
Accordingly, there is a need for a simple and effective technique for 
loading and removing articles from a single vapor condensation heating 
facility while providing substantially complete sealing of the drying 
chamber during the drying operation. 
SUMMARY OF THE INVENTION 
The instant invention is directed to a method for transferring an article 
into and through a heating facility having a condensation heating chamber 
in the lower portion thereof and a drying chamber in the upper portion 
thereof. The method comprises the steps of: projecting a first portion of 
a transfer member, located within the drying chamber, through an upper 
access means in the heating facility; attaching the article to said first 
portion; and moving the first portion to transfer the article thereon 
through the drying chamber and into the condensation heating chamber 
through a lower access means in the bottom of said drying chamber.

DETAILED DESCRIPTION 
In a preferred embodiment the instant invention is described as it relates 
to soldering articles by condensing hot saturated vapor thereon to reflow 
previously deposited solder to form a bond. However, such disclosure is 
for purposes of exposition and not for limitation for the instant 
technique may be used in various heating operations such as fusing, 
brazing, curing, etc. 
FIG. 1 is an isometric view of the instant closed, single vapor 
condensation soldering facility generally designated by the numeral 10. 
The facility 10 is comprised of a housing 12 having sidewalls 14--14, a 
top section 16 and a floor 18. A planar dividing member 22 divides the 
housing into a drying chamber 24 and a condensation soldering chamber 26. 
The condensation soldering chamber 26 has a plurality of immersion heating 
coils 28--28 in the lower portion thereof (see FIG. 2) and a set of 
condensing coils 32--32 mounted proximate the planar dividing member 22. A 
pressure relief apparatus 34 communicates with the soldering chamber 26 
via a conduit 36. 
The dividing member 22 has a substantially rectangular opening 42 with a 
first access door 44 rotatably mounted therein. The access door 44 has an 
arcuate surface 46 with opposed end segments 48--48. A first shaft 52 
extends normally from one segment 48 to a support bearing 54, while a 
second shaft 56, axially aligned with the first shaft extends from the 
other segment 48 through the wall 14 to a shaft rotating mechanism (not 
shown). One longitudinal edge of the arcuate surface 46 terminates in a 
planar ledge 58 while the other longitudinal edge terminates in 
substantially "U" shaped trough 62 (see FIG. 3). An elongated seal 64 
having a circular cross section is fixedly mounted on the underside of the 
dividing member 22 proximate the opening 42 as shown in FIG. 3. 
The top section 16 of the drying chamber 24 also has an opening 66 with a 
second access door 68 therein having an arcuate surface 71 opposed end 
segments 72--72 (only one shown) with a third shaft 74 extending normally 
from one end segment 72 and through the wall 14 to a shaft rotating 
mechanism (not shown). A fourth shaft (not shown), axially aligned with 
the third shaft 74, extends normally from the other end segment and 
terminates in a support bearing (not shown). 
A transfer means 76 is pivotably mounted on a shaft 77 which extends 
through the wall 14 for rotation by a mechanism (not shown). The shaft 77 
is rotatably mounted within a support member 78 which is fixedly attached 
to the inner surface of a wall 14. The means 76 is comprised of a pair of 
parallel arms 82--82 connected at their free ends 84--84 by a cross member 
86. 
As schematically shown in FIG. 4, the drying chamber 24 also has a drying 
air outlet 92 which communicates with a vapor recovery system 94, and 
connects back into the drying chamber through an opening 95 via a vapor 
recovery loop 96. A motor 97 mounted on one of the sides 14 of the 
facility 10 controls a blower 98 in the loop 96. 
In operation (see FIG. 2), a heat transfer liquid 102, such as Fluorinert 
FC-70 sold by the 3M Company, is raised to its boiling temperature (e.g., 
approximately 419.degree. F.) upon activation of the immersion heating 
coils 28--28. The vapor of the heat transfer liquid 102 is substantially 
confined in the soldering chamber 26 by the cooling coils 32--32 which are 
maintained at about 100.degree. F. 
Articles 112--112 to be soldered are placed in a basket 114 having a pair 
of hangers 116--116 extending from the upper portion thereof, as shown in 
FIGS. 1 and 2. The first access door 44 is then rotated to the closed 
position while the second access door 68 is rotated to the open position 
as shown in FIG. 2 and the transfer means 76 is rotated counterclockwise 
until the cross-member 86 projects through the opening 66. The basket 114 
with the articles 112--112 therein is lowered into the drying chamber 24 
and the hangers 116--116 positioned on the cross member 86 of the transfer 
means 76. The second access door 68 is then closed and the first access 
door 44 opened and the transfer means 76 rotated clockwise to lower the 
basket 114 into the primary vapor in the soldering chamber 26 as shown in 
FIG. 3. Following the soldering operation in the chamber 26, the transfer 
means 76 is rotated counterclockwise to remove the basket 114 with the 
articles 112--112 therein from the chamber 26 and hold them within the 
drying chamber 24 as shown in FIG. 4. The second access door 44 is rotated 
to its closed position to seal the drying chamber 24. At this time the 
drying chamber 24 is substantially fully sealed having no conveying or 
other apparatus passing through the chamber walls 14. 
At this time the vapor recovery system 94 is activated (see FIG. 4) to 
remove dragout vapor from the soldered articles 112--112 and vapor which 
may have escaped from the soldering chamber 26 into the drying chamber 24. 
The vapor recovery system 94 is the same as described in the 
aforementioned U.S. Pat. No. 4,264,299. In particular, FIG. 2 of that 
patent shows a recovery system comprised of a condenser, heaters and 
filters. The air and vapor mixture drawn from the drying chamber 24 passes 
through the condenser which chills the mixture to a temperature sufficient 
to cause condensation of a substantial portion of the vapor. Once the 
vapor is extracted from the mixture the condensate is collected and routed 
to a filtration system for further cleaning and routed back into the 
soldering chamber 26. Following condensation the resulting atmospheric 
mixture is passed through a heater to raise the temperature of the mixture 
prior to return to the drying chamber 12 thereby increasing the capacity 
of the atmosphere to absorb any primary vapor remaining in the drying 
chamber. The blower 98 recirculates the atmosphere in the drying chamber 
24 for a time sufficient to remove substantially all the heat transfer 
vapor therein. Such time will vary in accordance with the number and size 
of the articles 112--112 soldered and the volume of the drying chamber 24. 
Following the drying operation, the second access door 68 is opened (see 
FIG. 2) and the transfer means 76 rotated counterclockwise to project the 
end 84 through the opening 66 where an operator, or automatic transfer 
equipment (not shown) removes the basket 114 of soldered articles 112--112 
and places a fresh basket of articles to be soldered on the transfer 
means. 
Advantageously, the use of the rotatable access doors 44 and 68 and the 
pivotable transfer means 76 located fully within the condensation 
soldering facility 10 permit a slightly arcuate, vertical, movement of the 
articles 112--112 therein which minimizes the size of the facility. 
Additionally, the rotating access doors 44 and 68 minimize the size of the 
facility 10 and permit a compact enclosure. The arcuate access doors 44 
and 68 also result in less displacement of air within the facility than 
planar swinging doors. Additionally, such doors 44 and 68 cause less 
disturbance of the primary vapor in the soldering chamber 26. 
Most importantly the transfer means 76 does not require the feed through 
openings in the facility 10 for continuous conveying mechanisms that 
transfer the articles 112--112 to be soldered into the soldering chamber 
26 as are required in the prior art facilities. With such effective 
sealing of the instant drying chamber 12 the fluid loss due to escaping 
vapor is substantially minimized. 
A further embodiment of the instant invention is shown in FIG. 5 wherein an 
existing condensation heating facility 226, which may be a single vapor 
system shown in the aforementioned U.S. Pat. No. Re. 30,399 or a two vapor 
system shown in U.S. Pat. No. 3,904,102, is modified by mounting a drying 
apparatus 230 thereon. In the case of the two vapor system the apparatus 
230 can replace the secondary vapor blanket chamber. The apparatus 230, 
and the operation thereof, is substantially the same as incorporated in 
the integrated facility 10 shown in FIG. 1 and the same numbers are used 
to identify like elements. The lower portion of the apparatus 230 has a 
circumferential lip 232 which mates with the upper edge 234 of the 
condensation heating facility 226. The lip 232 may then be welded, bonded 
or otherwise sealed to upper edge 234 of the facility 226. 
It is to be understood that the embodiments described herein are merely 
illustrative of the principles of the invention. Various modifications may 
be made thereto by persons skilled in the art which will embody the 
principles of the invention and fall within the spirit and scope thereof.