Device for lowering and lifting supports holding objects to be coated with chemical substances in plating baths

A device for inserting a support holding an object into and removing said support with the object from a galvanizing bath comprises a transporting carriage and a lifting device for lifting and lowering said support. The support has outwardly extending arms engageable by the lifting elements of the lifting device. Guiding strips are provided for the lateral portions of the support to prevent its tilting during the lowering and lifting movement.

BACKGROUND OF THE INVENTION 
The present invention relates to a device which serves to lower a support 
with an object suspended thereon into a bath filled with a chemical 
substance and lifting said support from the bath after the coating 
process. 
Devices of the type under discussion are known. One of such devices has 
been disclosed in German patent document DE-PS 26 39 542. The lifting 
device movable up and down is disclosed in this German patent. A 
relatively short guiding rail having a U-shaped cross-section is pivotally 
connected to the lifting device. The guiding rail forms, with the aid of 
the coulisse control during the engagement of the lifting parts of the 
lifting device in the supporting parts of the object support, a guide for 
these supporting parts. This conventional device, however, has some 
disadvantages. As mentioned above, the guiding rail is relatively short so 
that safety against tilting is obtained only over a relatively short part 
of the entire downward and upward movement of the object support. It is, 
however possible in practice in some cases, that an undesired lifting of 
the lifting parts from the supporting parts, also after the lowering of 
the object support takes place over such a path that the supports ca be 
positioned outside the short guiding rail. Then, also possible is the 
tilting of the object support laterally and thus the damage to the object 
support, the object itself and further structural components of the 
device. The coulisse control and the pivoting ability of the guiding rail 
require a number of bearing places. Inasmuch as these bearing places are 
positioned at a small distance from the bath containing the most agressive 
chemicals, these bearing places can be quickly contaminated or chemically 
attacked. 
Should the tilting occur the guiding rail must take the entire tilting 
weight and transmit it through the bearing places to the lifting device 
and from the latter further to the transporting carriage. The guiding rail 
and the lifting device are, however, relatively sensitive and not very 
stable parts so that difficulties occur when the aforementioned tilting 
weight should be taken up by them. Furthermore, the conventional lifting 
device with the guiding rail must carry an approximation switch which in 
case of disturbance of the lowering and lifting parts would issue a 
respective signal responsive to such disturbance, and a further lowering 
of the lifting device would be stopped. This approximation switch is 
positioned above the bath and can be also damaged by an aggressive vapor 
or disturbed. In such a case an alert signal would not be issued and the 
motion of the lifting device would not be ceased, and the object support 
with the object suspended thereon would tilt to the side until its 
supporting parts are moved from the relatively short guiding region. 
A further disadvantage of the above-described conventional device resides 
in that the lifting device movable up and down must be provided with 
movable cables or wires for the approximation switch which can be 
therefore quickly damaged due to continuous movement. The aforementioned 
known device also presents a danger of buckling of objects during 
operation. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved device for 
lowering and lifting a support holding an object into and from a plating 
bath in which the object is coated. 
It is another object of the invention to provide such a guiding for the 
object support, that would ensure a robust and simple device, and on the 
other hand, would ensure a reliable functioning of the device in all 
possible cases of moving the lifting parts from the supporting parts. 
These and other objects of the invention are attained by a device for 
lowering and lifting supports holding objects into and from a bath 
containing chemical substances, particularly galvanic substances, for 
coating said objects, the device comprising a transporting carriage 
movable along the bath; a lifting device movable by said carriage; means 
to move said lifting device in a vertical direction up and down; each 
support for holding objects including two supporting arms, said lifting 
device including lifting means which are brought below said supporting 
arms upon movement from said transporting carriage; and guiding means for 
guiding said support in case of lifting off said supporting arms from said 
lifting means, said guiding means being fixed to said transporting 
carriage and extending over at least a substantial part of a lifting or 
lowering path of said lifting device and said support. 
The device may include connecting means to fix said guiding means to said 
transporting carriage, for example to the vertical struts of said 
carriage. 
If at any location the movement of the object on the support is blocked 
either due to the protruding part preventing an unobstructed motion of the 
object support or due to an irregular lowering, the lifting device is 
further lowered. In each of these cases, the extension of the guiding part 
over at least a substantial length of the lifting and lowering path is 
provided so that the tilting of the support holding an object, which 
tilting can damage the device, would not occur. Since the guiding part is 
rigidly secured to the transporting carriage the weight of the support as 
well as the weight of the object being coated, in case of the tilting of 
the support to the side, would be taken up by a very robust structural 
component, namely the transporting carriage or by its bars or rods. 
Therefore, the substantially lighter and more sensitive lifting device 
would not be loaded with an additional weight due to the above described 
tilting. Mechanical parts subject to attacks by vapors of the bath liquid, 
various hinge connections or the like, as well as electric wires or 
switches are not provided in the region near the bath. 
The supporting arms may be each positioned at each side of said support, 
respectively; said support further including two guiding portions; and 
guiding means including guiding strips fixed to said transporting carriage 
and arranged in pairs at each side of said support, the guiding strips of 
each pair being spaced from each other by a distance equal to a thickness 
of said guiding portion and each supporting arm so that said supporting 
arm with said guiding portion thereof is guided between two guiding strips 
of each pair. 
The guiding means is simple in structure and reliable in operation. 
The guiding strips may be made of a plastic resistant to chemically 
aggressive material vapors. 
Also, these strips can be metallic. 
The lifting device may include a traverse which supports said lifting 
means, said traverse being positioned to move from outside through a space 
between said guiding strips of each pair, said lifting means being lifting 
elements directed outwardly from an object held by said support and engage 
said supporting arms after said lifting elements have been brought below 
said supporting arms. 
In contrast to the device disclosed in the aforementioned disclosure DE-PS 
2,639,542, the structural components of the transporting carriage, which 
can be contaminated with the bath liquid during the movement of the 
transporting carriage along the bath, are positioned outside the guiding 
strips and the object support. Thus offers a possibility of constructing a 
wide and stable transporting carriage which can be supported during its 
movement on rails laterally of the bath. 
Also, in contrast to the device of the German document DE-PS 2,639,542, the 
frame carrying the lifting device and displaceable within the device is 
positioned above the bath. 
A further advantage of the device resides in that the guiding strips serve, 
at the same time, for a lateral guidance of the holding arms of the 
lifting device. 
The guiding strips are of such a length that in a lowermost position of 
said support said guiding strips terminate slightly above the respective 
guiding portion and the respective supporting arm of the support. Thereby 
the object support in the lowermost position thereof is never in the way 
of the transporting carriage with the lifting device when they are moved 
to other locations at the bath. 
The means to move the lifting device in a vertical direction may include 
cables or belts, at least one of said belts being in cooperation with a 
belt tension monitoring switch which after relaxing or ceasing a tension 
of said belt, causes a lowering movement of said lifting device. 
An approximation switch and connected therewith expensive movable electric 
cables of conventional devices can be omitted. Only one switch can be 
used, which can switch off the transporting means in case of lifting off 
the lifting device from the object support and which can be fixed on the 
transporting carriage substantially outside the area affected by vapors of 
the liquid contained in the bath. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DETAIlED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings in detail it will be seen that the device for 
lowering and raising supports holding objects or articles to be treated in 
a bath is shown in FIG. 1 schematically. The bath containing a chemical 
solution particularly a galvanizing solution is designated at 1. Objects 
2, for example electric circuit boards to be galvanized in bath 1, are 
inserted into and removed from the bath by means of a support or carrier 
3. The objects 2 are suspended for this purpose on the support 3 which is 
movable up and down in the vertical direction as shown in FIG. 1. Thereby, 
objects or boards 2 and the support 3 is shown by the solid line in the 
fully lowered position and, by the dash-dotted line, in the uppermost 
position. The maximal path of movement is indicated "h". 
The up-and-down movement of the support 3 is executed by means of a lifting 
device 4 the uppermost position of which is indicated in FIG. 1 by 
reference numeral 4'. Supporting belts 5 are provided in the device, which 
are movable together with the lifting device 4 and support 3 suspended 
thereon by means of a driving shaft 6 of a transporting carriage 7. For 
the sake of clarity supporting belts 5 are shown in FIG. 1 only in the 
upper position in which they hold the lifting device 4' and the article 
support 3 in the upper position 3' shown by the dash-dotted line. The 
transporting carriage 7 is movable by means of guide rollers 8 on guide 
rails 9 of the device in the direction which is perpendicular to the plane 
of the drawing. The object supports 3 can be brought to respective 
bath-containing containers or loading or unloading stations (not shown). 
In order to lift objects held on the support 3 from the bath 1, the 
transporting carriage 7 is moved along the bath until lifting elements 11 
provided on a bar or transverse 10 of the lifting device 4 and extended 
outwardly from a central axis of the lifting device are positioned below 
supporting arms 12 provided at two sides of the support 3. If the lifting 
device 4 is now raised by means of two belts 5 at two sides the lifting 
elements 11 engage with supporting arms 12, as shown in FIG. 3, and lift 
the support 3 to its uppermost position 3'. The lifting elements 11, as 
shown in FIG. 3, can be each comprised of two rail-type pieces which 
include with each other an acute angle and are adjusted in shape to the 
swinging arm 12 which is triangular in cross-section which has a 
downwardly directed acute angle. 
Should the lifting device 4 with the support 3 now be lowered from the 
uppermost position shown by the dash-dotted line and if, during this 
lowering, the process is blocked due to the tilting of a protruding part 
of the suspended object or due to any error, the support 3 with its 
supporting arms 12 will remain in a blocked position whereas the lifting 
device 4 with its lifting elements 11 will lower further. Thereby it is 
ensured by the lifting device that support 3 would not tilt in the 
directions of arrows 13 as shown in FIG. 3. The tilting motion of the 
support with the object suspended thereon, if not prevented, can lead to 
substantial damage to the object and also to the bath. In order to prevent 
such tilting two guiding strips 16 are provided at each side of the 
transporting carriage 7. The guiding strips 16 form a vertical guiding 
play or space 17 which has the width "a" for a guiding portion 18 of the 
supporting arm 12. The width of guiding portion 18 corresponds to that of 
play "a" which receives and guides the guiding portion 18. Guiding strips 
16 are made of plastic which is resistant to chemical aggression and are 
fixed to carriage 7. In the illustrated embodiment, strips 16 are rigidly 
secured by the connection bars 15 to vertical bars or rods 14 of the 
transporting carriage 7. The length of the guiding strips 16 is selected 
so that they extend at least over the substantial part of the lifting path 
"h" so that the object support 3 in all the positions in which its tilting 
can cause damage to the device itself or bath or objects suspended 
thereon, is secured against such tilting by the pairs of the guiding 
strips 16. These guiding strips 16 must terminate above the support 3 in 
its lowermost position so that the transporting carriage 7 with the 
respectively lowered lifting device 4, as shown by solid lines in FIG. 1, 
can be moved to the other place of the bath. 
Supporting belts 5 (or cables, chains, or the like) are formed of plastics 
and cooperate with a belt tension switch 19 which has a sensing arm 20 
applied to the belt 5. As soon as an error leading to the blocking of the 
lowering motion of the object support is determined and the lifting device 
in the process of the further lowering to the support will come to stop 
the tension of one or both belts 5 will increase, and the further lowering 
motion of belts 5 will be stopped by switch 19, 20. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
devices for moving supports with objects suspended thereon in a vertical 
direction to and from a galvanizing bath differing from the types 
described above. 
While the invention has been illustrated and described as embodied in a 
lifting device for objects to be galvanized, it is not intended to be 
limited to the details shown, since various modifications and structural 
changes may be made without departing in any way from the spirit of the 
present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention. 
What is claimed as new and desired to be protected by Letters Patent is set 
forth in the appended claims.