Aluminum soldering furnace

A vacuum aluminum soldering furnace comprising an evacuatable soldering cber having two lateral heating zones. The soldering chamber has a middle heating zone arranged parallel to the lateral heating zones and the heating element of the middle heating zone is preferably arranged removable from the soldering chamber.

The invention relates to a vacuum-aluminum soldering furnace, comprising an 
evacuatable soldering chamber which has two lateral heating zones. 
Aluminum-soldering furnaces with two lateral heating zones in the heating 
chamber are known. In this manner a charging cage is received between the 
heating zones. It is disadvantageous that an adjustment of the size of the 
soldering chamber to the size of the soldering parts is not possible. The 
band width of the soldering parts which are to be treated is relatively 
small due to the predetermined dimensions of the charging cage or frame, 
since this has a pregiven width. There exists however a need in existing 
furnaces to make a larger application width, in order with a single 
furnace to have the possibilities of variation with respect to the 
dimensions of the parts to be soldered from the smallest up to the largest 
sizes. Furthermore it is disadvantageous that is not always possible with 
two lateral heating zones to place parts which are to be soldered closely 
enough to the heating elements in order to obtain a uniform temperature 
distribution in the soldering chamber and on the part which is to be 
soldered. This is necessary for a good flow of soldering medium and a 
uniform formation of the soldered seam. 
The invention is based on the task of developing a vacuum aluminum 
soldering furnace, which for the treatment of parts to be soldered is 
variably formed with respect to the spaces which stand available for use 
and the heating elements of which furnace are nevertheless placed as close 
as possible to the parts which are to be soldered. 
The object of the invention is solved in the manner that the soldering 
chamber has a middle heating zone arranged parallel to the lateral heating 
zones, and that preferably the heating element of the middle heating zone 
is arranged removably from the soldering chamber. In this manner the 
possibility is provided that instead of the heretofore conventional 
charging in one cage or frame, two cages are used or a single larger cage 
is used which practically fills up the entire space of the soldering 
chamber and consequently it is suited for receiving larger soldering 
parts. The soldering furnace consequently is variably shaped with respect 
to its treatment space which stands available for use. With respect to the 
dimensions of the parts to be soldered, there results a larger application 
width. A uniform temperature distribution is attained by the possible 
adjustment of the heating zones to the conditions of the charge. 
Purposefully the heating element of the center heating zone is moveably 
suspended on an overhead rail and is able to move out from the soldering 
chamber. This advantageous formation of the invention permits a simple 
removal of the center heating element from the soldering chamber in the 
event of necessity. In this manner the overhead rail can be a telescopic 
rail. 
According to an advantageous embodiment of the aluminum soldering furnace 
in accordance with the invention, the soldering chamber has a box-shaped 
chamber housing, the latter being insulated with radiating sheet packets 
and having one or two gates, whereby a free space is left free over the 
chamber housing on the cover side up to the furnace housing, in which free 
space there are arranged the charge transport mechanism and the holder of 
the removeable center heating element. By this formation of the soldering 
chamber, in the unheated space between the housing cover and heating 
chamber cover, the different transport mechanisms are disposed protected, 
so that the transportation functions are not impaired even in continuous 
operation. 
Preferably the vacuum aluminum soldering furnace of the invention is formed 
as a two chamber furnace with an evacuatable preheating chamber, the 
latter being connected to the soldering chamber by means of a vacuum-tight 
heat insulating intermediate gate or door, in which preheating chamber 
there are arranged telescopic head running rails for the automatic 
charging and discharging of the furnace, the head running rails being 
moveable in the longitudinal direction relative to the soldering chamber 
as well as relative to an outer-lying overhead transportation system. 
Particularly in this manner the intermediate gate can be mounted 
transversely moveable. In a modified embodiment, the soldering furnace of 
the invention is formed as a three chamber continuous-heating furnace with 
a prechamber, a soldering chamber and a discharge chamber connected one 
behind the other.

The illustrated automatic two chamber furnace comprises a soldering chamber 
1, a preheating and purging chamber 2, respectively, and an overhead 
transportation system 8 for the charging cage or rack 3. The soldering 
chamber 1 is separated from the preheating chamber 2 by a vacuum-tight and 
heat-insulating door or gate 4, which gate is moveable in the transverse 
direction. 
Each chamber 1, 2 comprises two heating zones for the reception of two 
charging cages 3, the heating zones being arranged next to one another, 
whereby heating elements 9 and 10 are arranged on the side walls (heating 
element 10) and in the middle (heating element 9) between the charging 
cages 3. The center heating element 9 is suspended on an overhead running 
rail 6 in the cold part of the heating chamber housing 13. This cold part 
results by a soldering- or heating chamber-housing 13, which housing above 
its cover wall 12 has a free space toward the furnace housing 14, in which 
furnace housing 14 the transportation system can be arranged. The 
box-shaped soldering chamber housing 13 is lined inside with radiating 
sheet or plate packets 11 and particularly indeed on the side walls, the 
bottom wall, the rear and intermediate gate wall as well as approximately 
400 mm underneath the cover wall 12. Together they form the actual limits 
or boundaries of the soldering chamber 1. 
For disassembling of the center heating element 9, the latter can be moved 
out from the soldering chamber. If the center heating element 9 is removed 
from the chamber, the width of the heating zone is doubled and 
correspondingly larger charging cages or holders can be moved in. 
In the preheating chamber 2 there are disposed telescopic formed head 
running rails 7, which are moveable in the longitudinal direction to the 
soldering chamber 1 and to the outer-lying overhead transportation system 
8. The latter serves for the automatic charging and discharging of the 
furnace. Between the soldering chamber 1 and the preheating chamber 2, a 
box-shaped intermediate gate housing is flanged on vacuum-tightly. The 
intermediate gate 4 comprises a. a vacuum-tight gate and b. a heat 
insulating radiating sheet packet which is located on each side of the 
gate. The intermediate gate is moveable transversely to the axis of the 
furnace for the opening and closing, respectively. Moreover both chambers 
1 and 2 are provided with separate pump systems, which pump systems are 
suitable for evacuating (pumping-out) up to the high vacuum range. 
The aluminum soldering furnace operates as follows: 
First the soldering chamber 1 is evacuated up to the high vacuum range and 
is heated up to the soldering temperature. Then the front gate 5 of the 
preheating chamber 2 is opened laterally, transversely to the furnace 
axis, and the overhead telescopic rails 7 are moved out up to the 
outer-lying transportation system 8, on which transportation system the 
charging cages 3 have been brought loaded. The charging cages 3 are then 
shifted on the telescopic rails 7 and the latter move back into the 
preheating chamber 2. The front gate 5 is closed. 
Then the preheating chamber 2 is evacuated and the heating is turned-on. 
After the charge is preheated to approximately 300.degree. C. and the 
desired vacuum is achieved, the intermediate gate 4 is opened to the 
evacuated soldering chamber 1. Both chambers have the same vacuum. 
The telescopic rails 7 up to the transportation system are moved out into 
the soldering chamber and the charging cages 3 are transported via the 
rails 7 into the soldering chamber 1. Subsequently the telescopic rails 7 
are moved back into the preheating chamber 2 and the intermediate gate 4 
is closed vacuum-tightly. 
Now the charge is heated up to the soldering temperature and is maintained 
there for a corresponding time. After termination of the soldering holding 
time, the intermediate gate 4 is opened and the charge cage 3 or the 
charge cages 3 are moved into the prechamber 2. When the charge is cooled 
down there, the prechamber 2 can be discharged. If a cooling down is not 
necessary, the charge can be removed directly from the prechamber 2. 
All transportation functions between the prechamber 2 and the soldering 
chamber 1 proceed automatically. The charging and discharging of the 
prechamber 2 can take place either automatically or manually. 
In an extended embodiment the two chamber system can be enlarged by a third 
chamber in back of the soldering chamber 1, which third chamber then 
functions as a discharging chamber. In this manner the system can be run 
in continuously running operation and the performance or efficiency of the 
system is increased. As an alternative for lower performances or 
efficiences, the furnace can be embodied even as a one chamber system 
comprising only the soldering chamber 1.