U.S. patent number 3,765,436 [Application Number 05/166,425] was granted by the patent office on 1973-10-16 for control device for two metallic salt components in electroplating baths.
Invention is credited to Rainer Beule, Gunter Dreyer, Willy Dziomba, Gerhard Wolf.
United States Patent |
3,765,436 |
Dziomba , et al. |
October 16, 1973 |
CONTROL DEVICE FOR TWO METALLIC SALT COMPONENTS IN ELECTROPLATING
BATHS
Abstract
A device for controlling two metallic salt components in an
electroplating bath has a sensor for the bath concentration, a
sensor for the bath density, two conveyers for supplying respective
components into the bath, and limit switch circuits actuating the
respective conveyer in response to predetermined indications of the
sensors.
Inventors: |
Dziomba; Willy (Wolfsburg,
DT), Beule; Rainer (Wolfsburg, DT), Wolf;
Gerhard (Wolfsburg, DT), Dreyer; Gunter
(Kl.-Sissbeck, DT) |
Family
ID: |
5780519 |
Appl.
No.: |
05/166,425 |
Filed: |
July 27, 1971 |
Foreign Application Priority Data
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Aug 22, 1970 [DT] |
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P 20 41 815.9 |
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Current U.S.
Class: |
137/88;
137/93 |
Current CPC
Class: |
G05D
21/02 (20130101); Y10T 137/2499 (20150401); Y10T
137/2509 (20150401) |
Current International
Class: |
G05D
21/00 (20060101); G05D 21/02 (20060101); G05d
011/08 () |
Field of
Search: |
;137/88,87,2,3,4,5,90,91,92,93,98,101.19,112 ;204/88 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nilson; Robert G.
Claims
Having thus described the invention, what we claim as new and
desire to be secured by Letters Patent, is as follows:
1. A control device for controlling the supply of two metallic salt
components in an electrolytic bath the density of which is defined
substantially by its total salt content,
comprising, in combination,
concentration sensing means operable for detecting the
concentration of one of said two salt components in said bath,
density sensing means operable for areometrically detecting the
density of said bath,
first limit switching means preset for a nominal indication of and
controlled by said concentration sensing means,
first conveying means operable for supplying said one salt
component into said bath,
second conveying means operable for supplying said other salt
component into said bath,
said first switching means cooperating with said conveying means so
as to activate said first conveying means when the concentration of
said one component within said bath falls below said nominal
indication and, alternatively, said second conveying means when
said concentration sensing means detects the concentration of said
one component corresponding to said nominal indication, and
second limit switching means connected in series with said first
switching means and controlled by said density measuring device to
inactivate both said first and second conveying means when the
density of said bath exceeds a preset limit value.
2. A control device according to claim 1, wherein said first limit
switching means includes a double pole switch for alternatively
connecting said first and second conveying means to respective
poles of said first limit switching means, and said second limit
switching means includes a single pole switch connected in series
with said double pole switch for energizing either conveying means
when actuated.
3. A control device according to claim 1, further comprising
temperature sensing means, third limit switching means adjustable
for a critical temperature range of said bath and controlled by
said temperature sensing means for interrupting said first and
second limit switching means.
4. A control device according to claim 3, further comprising a
third signalling circuit actuated by said third limit switching
means.
5. A control device according to claim 1, wherein each of said
first and second limit switching means includes a limit switching
indicator.
6. A control device according to claim 5, wherein said limit
switching indicators are adjustable.
7. A control device according to claim 1, further comprising two
signalling circuits respectively connected in parallel with said
first and second conveying means and controlled by said first limit
switching means.
8. A control device, as claimed in claim 1, comprising an electric
circuit including several branches, one of said branches including
said concentration sensing means, another branch including said
density sensing means, and a third branch including a temperature
sensing means, all of said sensing means being immersed in said
bath, a limit switching means connected in each branch, a fourth
branch including said limit switching means in series, the limit
switching means of said concentration sensing means having a double
pole whereby when contact is made with one pole one of said
conveying means is energized to supply one salt component to the
bath and, respectively, when contact is made with the other pole
the other conveying means will supply the other salt component,
when the fourth branch is uninterrupted.
9. A control device according to claim 1 further including setting
means for adjusting switching limits of said first and second
switching means, respectively.
Description
BACKGROUND OF THE INVENTION
The invention relates generally to a device for controlling
electroplating baths. More particularly, the invention relates to a
device for controlling two metallic salt constituents in an
electroplating bath the density of which is substantially
determined by its total salt content, and which is provided with a
first sensor for detecting the concentration of one of the two
components, with a second sensor for aerometrically detecting the
density of the bath, and with an arrangement for determining the
concentration of the other components as the difference between the
indications of the two sensors.
It has been known how to determine the salinity of electroplating
baths of the above mentioned type by means of so-called wet
analysis. Wet salinity is determined by measuring the conductivity
of the bath. The disadvantage of such conventional method resides
in that its applicability is considerably limited by the following
operating conditions: the total salt content can be accurately
determined only when the solution contains only one metal salt
component; or if all components in the solution change
approximately at the same ratio; or if there prevails the change of
one component in the solution.
There have been known also other embodiments of the measuring and
controlling devices for electroplating baths such as described, for
example, in the DDR Pat. No. 68,120. These known devices, however,
have a very complicated structure and inconvenient adjustability
for various bath compositions and, consequently, they are not fully
satisfactory for various controlling programs.
It is therefore an object of this invention to avoid the
disadvantages of prior art. More particularly, an object of this
invention is to provide a control device for electroplating baths
having two metal salt components the density of which is determined
predominantly by the total metal salt content, which makes it
possible to supply individual components of the bath in arbitrary
proportions in response to a preset nominal value of the content of
those components.
Another object of this invention is to provide a control device of
the aforementioned type which enables an instant and automatic
adjustment of two components of the electroplating bath in response
to changed conditions of the latter.
SUMMARY OF THE INVENTION
According to the present invention the above objects are attained
by providing switching circuits having nominal or desired value
adjusting means for each of the aforementioned sensors, conveying
devices for the two components, the driving means of the conveying
devices being in circuit relation with power supply and switching
circuits in such a manner that each of the conveying devices is in
series connected to a limit switch which closes when the density
indication falls below a predetermined value. This switch
cooperates with another (second) in series connected switch coupled
to the first sensor for measuring the concentration, thereby
actuating the conveying device for one component. The other
conveying device is actuated by the latter switch when the
indication of the sensor for detecting the concentration of one
component of the bath falls below a predetermined nominal value. It
is advantageous if the second switch is carried out as a
two-contact switch which, when being in an actuated position closes
the power supply circuit for one of the conveying devices and in
its actuated position closes the feeding circuit for the other
conveying device.
In a further development of this invention, the controlling
arrangement is provided with a third sensor for detecting the
temperature of the bath, connected to a third limit switch circuit
having a switch connected in series with the first and second
switches to interrupt the feeding of the conveying devices and thus
the supplying of the components into the bath if the temperature of
the bath is out of a predetermined critical temperature range. The
limit switch circuits are equipped preferably with switching
indicators or measuring instruments having adjustable limiting or
stop contacts on their scales.
In order to enable visual checking of the operation of the
arrangement, the device is provided with signalling circuits
associated with respective limit switch circuits to indicate
visually the operation of individual conveying devices. The signal
lamp of each signalling circuit is preferably connected to a
two-position switch which is controlled by the first limit switch
circuit connected to the density sensor. The signal lamp for
indicating the preset critical temperature range of the bath is
connected across the series of limit switches controlling the
conveying devices, and is actuated together with a limit switch
controlled by the temperature sensor.
The advantages attained by the invention reside particularly in the
fact that the resulting device has a universal applicability. By
means of the device of this invention it is possible to control and
adjust any combination of metallic salts without complicated and
time consuming wet analyses or without the reconstruction of the
measuring and controlling device. This advantage is particularly
important for small workshops which hitherto, due to the small
amount of processed pieces and due to the size of electroplating
baths, have not been in a position to provide for each
electroplating process a special bath.
BRIEF DESCRIPTION OF THE DRAWING
For a better understanding of the invention, together with other
and further objects and advantages thereof, reference is made to
the following detailed description of the single FIGURE of the
accompanying drawing, which FIGURE is a schematic diagram of a
control device for adjusting two metallic salt components in
electroplating baths according to this invention.
DETAILED DESCRIPTION
Referring now to the drawing, a measuring cell 1 which is located
preferably in a branch part of a tank 1' for an electroplating bath
26 is provided with a first sensor consisting of electrodes 3 and
4, a second sensor 2 for areometric detection of the density, and a
third sensor 5 for detecting the bath temperature.
The sensor 2 supports on its top a metal segment 20 which enters a
coil of a measuring bridge 21 (inductive measurement). It is, of
course, possible to employ other types of conversion, such as
capacity measurement or pick-up, for example.
To screen the measuring cell 1 against outer disturbances, the
entire measuring cell 1 is surrounded by a grounded metal lattice
6. Connecting conduits 7' and 7 are designed for connecting the
measuring cell 1 to the corresponding outlets in the tank 1' of the
proper electroplating bath 26.
The electrodes 3 and 4 of the first sensor are connected via an
amplifier 10 to a switching device 8 which has adjusting means
(preferably limit stops) for adjusting the nominal or desired value
of the first sensor (electrodes 3 and 4). The second sensor 2 is
connected via the measuring bridge 21 (without the employment of an
amplifier) to a second switching device 9 which is also equipped
with an adjuster for setting the limit or desired value of the
second sensor 2. Advantageously, the switching devices 8 and 9 are
made in the form of measuring indicators having adjustable limit
stop contacts 8' and 9', each being adjustable in its position with
respect to the pointer of an indicator, as indicated by double
arrows in the devices 8 and 9.
The switching device 9 closes in response to the indication from
the output of bridge 21 its contact relay 14, which energizes the
relay 24 and closes the relay contact 15. Provided that contact 16
is closed, as will be described below, the power supply circuit O
and R is connected through one contact of the switch 13 to a
conveying device 23 provided for conveying through a conduit 30 the
other of two metallic salt components into the electroplating bath
26'.
On the other hand, the switching device 8 closes through relay
contact 12 the energizing circuit O and R for the relay 19 which,
in turn, switches over to the other contact of the switch 13,
thereby stopping the conveying device 23 and actuating another
conveying device 22 for the first metallic salt component. It will
be understood that the relays 19 and 24 serve merely for the
amplification of controlling or switching pulses of the switching
contact 14 and 12 pertaining to switching devices 9 and 8.
Parallel to the double pole switch 13 there is arranged a similar
double pole switch 13' which controls signalling devices 22' and
23', operating in a similar manner as the switch 13 controls the
conveying devices 22 and 23, thus visually indicating the operation
of an actuated conveying device.
In the shown embodiment, the conveying devices 22 and 23 can
operate only when a temperature measuring and switching device 17
which is coupled to the temperature sensor 5, maintains the switch
16 in its closed position. The limit switching and temperature
measuring device 17 can be adjusted to indicate a predetermined
critical temperature range of the bath. Simultaneously with the
switch 16, the device 17 controls a switch 16' connected across the
clamps of a power supply circuit O and R. The switch 16' controls
the actuation of a visual signalling device 18.
The mode of operation of the control device for adjustment of two
metallic salt components in electroplating baths 26 of the
invention will be explained by way of an example in connection with
a nickel bath. In a nickel bath of conventional composition
(Watts-type) there are contained two metallic salts, namely nickel
chloride and nickel sulphide. If the second sensor 2, which
areometrically detects the density of the bath, displaces the
pointer of the limit switch indicator 9 beyond a predetermined
position corresponding to nominal or desired value of the total
concentration of the metallic salt in the bath, the switching relay
contact 14 closes the feeding circuit for the relay 24 and,
consequently, the relay contact 15 becomes also closed. Provided
that switch 16 is in its closed position and switch 13 is in its
unactuated or normal position closing the right hand contact
connected to the conveying device 23 for supplying nickel sulphide,
the latter conveying device becomes actuated and the nickel
sulphide component will be supplied into the bath. The double pole
switch 13, as illustrated, actuates the conveying device 23 in its
rest position which occurs only when the switching device 8,
adjusted to the desired or nominal indication of the first sensor
(3 and 4) for the detection of the nickel chloride content in the
bath, fails to indicate any deviation from the nominal value of the
nickel chloride concentration. Should the electrodes 3 and 4,
however, detect any deviation from the preset nominal value of the
nickel chloride, the first switching device 8 will become actuated,
the switch 12 closes and the limit switch indicator 19 displaces
the switch 13 to the left hand position, thereby energizing the
conveying device 22 for nickel chloride. The conveying of nickel
chloride or of nickel sulphide can be attained only when the
temperature controlling switch 16 is in its closed position. The
latter condition exists when the temperature sensor 5 in connection
with the nominal adjustor 17 detects a preset range of tolerances
for the temperature of the bath. Parallel to the series connection
of the switches 15 and 16 there are arranged switches 13' and 16'
controlling signalling devices 22', 23' and 18, designated for
visual observation of the operation of the device.
In the illustrated device according to the invention, the sequence
of controlling steps is as follows: the conveying device 22, such
as for example a conveying pump, first refills the nickel chloride
until its desired concentration is attained and the contact of the
switch 13 is displaced. Subsequently, there follows the addition of
nickel sulphide until the nominal or desired value of the total
metal salt contact is detected and the switch 15 is opened. If,
however, the bath temperature is not in the predetermined range of
tolerances, the switch 16 prevents the aforementioned regulation of
the bath concentration unless the bath is reset to its
predetermined temperature condition.
Further modifications will also occur to those skilled in the art
and all such are considered to fall within the scope and spirit of
the invention as defined in the appended claims.
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