Note: Descriptions are shown in the official language in which they were submitted.
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Method for controlling a casting plant
The invention relates to a method for controlling a casting
plant having at least one mould for receiving a fluid material,
the fluid material solidifying in the mould during a solidifying
time. The invention further relates to a casting plant having at
least one mould, a casting plant system comprising this casting
plant, a computer programme and a computer programme product.
Motor components but also other components are nowadays produced
by a casting process in casting plants. During the casting
process, a solid member having a specific shape in accordance
with the shape of the mould is produced from a fluid material
after the material has solidified. In this instance, a constant
concern is to configure the production process in an efficient
manner and in particular to improve the production speed in
addition to reducing incorrectly produced components.
During casting, the efficiency of the production process is
particularly dependent on the solidifying time, that is to say,
the time during which the initially fluid material cools and
solidifies in a mould of the casting plant so that it can be
removed from the mould. The solidifying time also significantly
determines the cycle time and consequently the production rate
of the production process.
In conventional methods for controlling a casting plant of the
prior art, the solidifying time is a constant time period. In
other words, a cast component is always removed from the mould
after the same time. In this instance, the solidifying time is
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generally configured at maximum load with regard to the
operation of the casting plant in order to increase production.
However, a problem in the prior art is that, on the one hand,
the casting process is subjected to a plurality of non-constant
factors which can be influenced only to a limited extent or not
at all. This includes, for example, the ambient temperature of
the casting plant or the temperature of the materials used.
On the other hand, undesirable and unavoidable interruptions to
the casting process occur again and again, for example, as a
result of defective components, maintenance work, technical
errors, etc. After an interruption, the casting plant has to be
re-started once more and the mould in particular has to be
brought back to temperature. However, since the solidifying time
is configured to be constant and for operation at maximum load,
interruptions and unavoidable influences with respect to the
casting process result in defective components. On the other
hand, a constant solidifying time may also result in a component
remaining in the mould for longer than is necessary.
Therefore, an object of the present invention is to provide a
method for controlling at least one casting plant, which method
allows more efficient production of components, particularly
even under non-optimum conditions.
The object which is previously derived and set out is achieved
according to a first aspect of the invention by a method for
controlling a casting plant having at least one mould for
receiving a fluid material, the fluid material solidifying in
the mould during a solidifying time. The method comprises the
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steps that at least one process parameter is detected during the
production process and the solidifying time is determined in
accordance with the process parameter detected.
Unlike the prior art, the solidifying time is not predetermined
as a constant time according to the invention but instead it is
variable and is determined during the production process in
accordance with at least one process parameter. In other words,
the solidifying time may change during the production process in
accordance with a detected process parameter.
A casting plant having at least one mould is controlled with the
method according to the invention. A mould which may in
principle have any shape in accordance with the set shape of the
component to be produced is filled with a fluid material. The
initial material may preferably be a fluid metal. In order to
fluidise a metal, it is heated accordingly.
The fluid and hot material introduced into the mould cools in
the mould and solidifies to form a solid member. The solidifying
time, that is to say, the time period between the mould being
filled and the time of removal of the cast component, is
determined according to the invention in accordance with a
process parameter detected during the production process.
The term process parameter is intended to be understood to be a
parameter which is characteristic of the casting process or
which influences it directly or indirectly. In particular, the
process parameter is a parameter which is characteristic of the
solidifying time or which influences it directly or indirectly.
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By the solidifying time being determined (automatically)
according to the invention in accordance with a parameter
detected during the production process, the reject rate can be
reduced. The production rate and the efficiency of the
production method can also be significantly increased even under
non-optimum operating conditions. In particular, interruptions
to the production process and unavoidable influences may be
taken into consideration by the method according to the
invention. Even small reductions in the cycle time in the order
of seconds result in significantly higher production rates.
In principle, the at least one process parameter can be detected
at any times. According to a first embodiment of the method
according to the invention, a current process parameter can be
detected during a casting process of a component to be produced.
The term casting process is intended to be understood to be an
individual casting operation of a component during the
production process of a large number of components. In
particular, at least one current process parameter can be
detected for each component to be cast during the casting
process of the corresponding component. The solidifying time for
the component (currently) to be produced can preferably be
determined in accordance with the detected current process
parameter. In other words, the solidifying time of the component
to be cast may depend (directly) on a current process parameter.
Current influences and particularly changes with respect to the
casting process can be taken into consideration (in a timely
manner). In particular (automatic) real-time control of the
solidifying 'time is possible. The cycle time and quality can be
improved.
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According to a preferred embodiment of the method according to
the invention, the at least one process parameter can be
detected continuously. Continuous detection of a process
parameter at least during the casting process of a component
(currently) to be cast results in exact and (constantly) current
measurement values. Alternatively, the process parameter may be
detected at predeterminable time intervals, in particular at
periodic time intervals. The time intervals may particularly be
selected so that the measurement values are sufficiently current
to be able to take into consideration, for example, influences
which act on the casting process in an adequate and timely
manner. For example, a value may be detected every second,
preferably every half second.
It will be understood that a plurality of different process
parameters of the production process, in particular the casting
process, can be detected. Different process parameters can also
be detected in different manners, that is to say, continuously
or at predeterminable time intervals.
Furthermore, the determination of the solidifying time can be
carried out according to another embodiment of the method
according to the invention in accordance with a comparison of
the detected process parameter with at least one set process
parameter. A set process parameter, such as a limit value, may
be predetermined. By comparing the (current) process parameter
with a suitable set process parameter, the solidifying time can
readily be determined. For example, the set process parameter
can be predetermined so that, when the current process parameter
exceeds or falls below the set process parameter, this indicates
the time from which the mould can be opened. In other words, at
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least one condition can be predetermined so that, when the
condition is fulfilled, adequate solidifying of the material has
been carried out and the cast component can be removed.
At least two set process parameters may preferably be provided
for a process parameter. An upper and a lower limit value which
define a permitted range may further be predetermined. Only if
the current process parameter is in this range can the mould be
opened. Furthermore, additional set criteria can be
predetermined. For example, it may be considered in a
continuously changing process parameter whether it is (currently)
changing in an increasing or decreasing manner.
In principle, different process parameters of the production
process are suitable for determining the solidifying time.
Process parameters which characterise or influence the
solidifying time may preferably be detected. It has been
recognised that the temperature of the mould or the temperature
of the material located in the mould is particularly suitable
for determining the solidifying time. In particular, it is
possible to derive from the temperature of the material in the
mould whether the initially fluid material has solidified
(sufficiently) and whether the mould can be opened. A set value
temperature may preferably be predetermined, at which it is
ensured that the fluid material used has solidified to such an
extent that a cast component can be removed. In other words, the
optimum removal time can be determined for each component. The
removal time, that is to say, the variable solidifying time, may
particularly depend on the current temperature of the material
or component. On the one hand, an excessively early removal time
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at which adequate solidifying has not yet begun can be prevented.
On the other hand, unnecessarily long solidifying times can be
prevented. The cycle time can be improved with a simultaneous
reduction in the number of defective components.
As already described, additional criteria may be predetermined.
For example, it may be considered whether the temperature of the
mould or the temperature of the material in the mould is
increasing or decreasing. For instance, when the mould is filled,
the detected temperature may initially increase and accordingly
initially be below a set value. In order to nevertheless ensure
that the material has solidified, the temperature progression
can be taken into consideration. It is possible to conclude from
a decreasing temperature progression that the material is
cooling and solidifying. In addition to reaching, falling below
or exceeding a set temperature, there may be provision for the
temperature progression to be decreasing in addition to
determining the solidifying time.
It will be understood that the temperatures of the mould and the
material in the mould can be detected according to other
variants of the invention.
Furthermore, according to another embodiment of the method, the
solidifying time of the component to be produced can be
determined in accordance with the solidifying time of at least
one previously produced component. In particular, results from
previous casting processes may be stored and considered. For
example, it is possible to conclude a defective measurement from
an unusual discrepancy between the current solidifying time and
the solidifying time of the previously cast component.
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In order to prevent excessively early opening of the mould in
the event of incorrect detection of the (current) process
parameter, at least one set solidifying time may preferably be
predetermined. For example, at least one minimum set solidifying
time may be predetermined. The minimum set solidifying time may
particularly be selected so that at least adequate solidifying
of the material has begun, which solidifying prevents fluid
material from flowing out of the mould when the mould is opened
and resulting in damage to the casting plant or other devices.
Furthermore, a maximum set solidifying time may be predetermined.
Incorrect measurement of the at least one process parameter may
result not only in a condition, such as a set process parameter
being reached, being achieved too early, but also in a condition
not being achieved or being achieved too late. In order also to
allow removal in this instance, a maximum set solidifying time
may be predetermined, the mould being able to be opened and the
component being able to be removed (always) when the maximum set
solidifying time has been reached. It will be understood that
corresponding errors can be displayed for a user.
According to a particularly preferred embodiment of the method
according to the invention, the above-described criteria, in
accordance with which the solidifying time, that is to say, the
removal time of the cast component, can be determined, may be
taken into consideration in a formula. For example, different
conditions can be associated with each other logically in a
formula. In particular, a set value temperature being reached
may be associated with the conditions that the temperature
progression is decreasing and a minimum solidifying time has
been exceeded.
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According to another embodiment of the method, the at least one
set process parameter may further be determined before the
production process. All the set values, in particular a
previously described formula, may preferably be determined
before the production process. In particular, the at least one
set solidifying time can be established before the production
process.
According to another preferred embodiment, the at least one set
process parameter can be determined in accordance with the fluid
material, the casting plant, the state of the casting plant
and/or the shape of the mould. For example, different fluid
materials may have different solidifying temperatures. Therefore,
the at least one set temperature may be different for different
materials. Similarly, the mould shape used, for example, the
size, diameter thereof, etcetera, may require different set
process parameters in order to achieve optimum results. However,
different casting plant types and the state of the casting plant
may also have some influence on an optimum solidifying time. It
will be understood that other criteria may be used for
determining the set process parameter. It will also be
understood that a set solidifying time can also be determined in
a similar manner in addition to a set process parameter.
There may further be provision for the at least one set value
parameter also to be able to be determined (again) during the
production process at predeterminable time intervals.
Another aspect of the invention is a casting plant having at
least one mould for receiving a fluid material. In the casting
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plant, there is provided at least one sensor device which is
configured to detect at least one process parameter during the
production process and there is provided at least one control
device which is configured to determine the solidifying time in
accordance with the detected process parameter.
The casting plant is particularly constructed to carry out the
above-described method.
The casting plant further comprises at least one mould having a
predeterminable shape. The shape is particularly dependent on
the component to be produced. The mould may be filled with a
fluid material, such as a metal or the like. After the material
has solidified, the mould may be opened and the solidified
component may be removed.
At least one suitable sensor device is further provided in order
to detect at least one previously mentioned process parameter
during the production process and in particular during a casting
process.
A control device is further provided. The control device, for
example, a microcomputer, a Digital Signal Processor (DSP) or
the like, is configured to process the detected process
parameter and to determine the optimum solidifying time, that is
to say, the removal time, for the cast component in accordance
with the process parameter.
The production rate and the efficiency of the production method
can be significantly increased even under non-optimum operating
conditions.
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According to a first embodiment of the casting plant according
to the invention, the sensor device may be a temperature sensor.
The temperature sensor may particularly be arranged on or in the
mould. A process parameter which is significant for the casting
process can be detected by means of a suitable temperature
sensor.
According to a preferred embodiment of the casting plant
according to the invention, the temperature sensor may be
arranged in such a manner that the temperature of the material
in the mould can be detected. As already described, the
solidifying time actually required is dependent (inter alia) on
the temperature of the material in the mould. For example, the
temperature of the mould can be measured. The temperature of the
material in the mould can be derived from this temperature.
In principle, the temperature of the material in the mould may
be detected in a contactless manner or with contact. In a
particularly preferable manner, the at least one temperature
sensor may be arranged in such a manner that the temperature
sensor directly contacts the material in the mould. The
temperature can be detected in a particularly precise manner.
The at least one set temperature value can thereby be set
practically without any tolerance as a result of measurement
inaccuracies. The cycle time may be significantly reduced
without any loss of quality.
Another aspect of the invention is a casting system comprising
at least one above-described casting plant and a central control
unit configured to determine at least one set process parameter.
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The casting system may also have two or more casting plants
which can communicate with the central control unit. The central
control unit, in particular a central processing device having a
database, may be in the form of a superordinate control unit.
For example, information concerning the casting plant, such as
the state of the casting plant, the shape of the mould, etcetera,
and concerning the components to be produced and initial
materials, can be stored in the database. At least one optimum
set process parameter, preferably a previously described formula
for determining the solidifying time, can be derived from that
information. Information from a plurality of casting plants
which are connected to the central control unit can further
advantageously be used in order to determine an optimum set
process parameter, preferably a formula for determining the
solidifying time.
Another aspect of the invention is a computer programme having
instructions which can be carried out on a processor in such a
manner that a casting plant is controlled by means of the above-
described method.
Yet another aspect of the invention is a computer programme
product comprising an above-described computer programme having
instructions which can be carried out on a processor in such a
manner that a casting plant is controlled by means of the above-
described method.
According to another embodiment, there is provided a method for
controlling a casting plant having at least one mould for
receiving a fluid material, the fluid material solidifying in
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the mould during a solidifying time, at least one process
parameter being detected during the production process and the
solidifying time being determined in accordance with the
detected process parameter.
According to another embodiment, a current process parameter is
detected during a casting process of a component to be produced
and the solidifying time for the component to be produced is
determined in accordance with the detected, current process
parameter.
According to another embodiment, the process parameter is
detected continuously or at predeterminable time intervals.
According to another embodiment, the determination of the
solidifying time is carried out in accordance with a comparison
of the detected process parameter with at least one set process
parameter.
According to another embodiment, the process parameter is the
temperature of the mould or the process parameter is the
temperature of the material in the mould.
According to another embodiment, the solidifying time of the
component to be produced is determined in accordance with the
solidifying time of at least one previously produced component.
According to another embodiment, at least one set solidifying
time is predetermined.
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According to another embodiment, at least the set process
parameter is determined before the production process.
According to another embodiment, the set process parameter is
determined in accordance with the material, the casting plant,
the state of the casting plant and/or the mould shape.
According to another embodiment, a casting plant having at least
one mould for receiving a fluid material is provided, there
being provided at least one sensor device configured to detect
at least one process parameter during the production process and
there being provided at least one control device configured to
determine the solidifying time in accordance with the detected
process parameter.
According to another embodiment, the sensor device is a
temperature sensor, the temperature sensor particularly being
arranged on or in the mould.
According to another embodiment, the temperature sensor is
arranged in such a manner that the temperature of the material
in the mould can be detected.
There are now a large number of possibilities of configuring and
developing the method according to the invention for controlling
at least one casting plant, the casting plant according to the
invention, the casting plant system according to the invention,
the computer programme according to the invention and the
computer programme product according to the invention. To this
end, reference may be made, on the one hand, to the patent
claims which are subordinate with respect to the independent
_
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patent claims and, on the other hand, to the description of
embodiments in conjunction with the drawings, in which:
Figure 1 is a schematic view of a first embodiment of a casting
plant system having a casting plant according to the present
invention; and
Figure 2 is a flow chart of an embodiment of a method for
controlling a casting plant according to the present invention.
Figure 1 is a schematic view of a first embodiment of a casting
plant system 2 having an exemplary casting plant 4 according to
the present invention.
The casting plant 4 illustrated is configured to produce, in
particular to cast, components 6. For example, motor components
or the like can be cast. To this end, a fluid material 8, such
as a fluid metal, is provided. The metal may be in particular
aluminium or an aluminium alloy.
The fluid material 8 is introduced into a mould 10, also
referred to as a casting mould 8. In order to produce components
6 having cavities, it is further possible to provide mould
substances 12. Cores can, for example, be formed with the mould
substances 12 in order to produce subsequent cavities in the
components 6. For example, suitable sands are used as mould
substances 12 for a core.
The casting plant 4 further has a control device 14. The control
device 14 may be configured to control the casting plant 4 or
the casting process. The control device 14 may have suitable
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processing means 16, such as a processor, storage means,
interfaces, etcetera, in order to predetermine different control
parameters for the casting process. For example, it is possible
to predetermine cooling parameters, heating parameters for
heating mould portions of the tool mould and/or suitable cutting
and supply parameters.
The control device 14 is particularly configured to determine
the solidifying time, that is to say, the removal time, as will
be set out in greater detail below.
In the present embodiment, the casting plant 4 further comprises
a sensor device 18. The sensor device 18 is in particular a
temperature sensor 18 for detecting the temperature of the mould
10 and/or the material in the mould 10.
The temperature of the material in the mould 10 can preferably
be detected directly. For example, a temperature sensor 18 can
be arranged in such a manner that it directly contacts the
material in the mould 10. Alternatively or additionally, the
temperature of the mould 10 can be measured. For example, the
temperature of the material in the mould 10 can be derived from
that temperature.
The temperature sensor 18 detects at predetelminable time
intervals or continuously at least one of the above-mentioned
temperatures. The temperature values detected can be provided
for the control device 14 in a suitable form for further
processing.
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It will be understood that, according to other variants of the
present invention, a plurality of temperature sensors 18 may be
provided in order to detect the temperature of the mould 10
and/or the material in the mould at different locations. It will
further be understood that additional detection devices may be
provided, for example, in order to detect the ambient
temperature and the like.
The casting plant 4 may further be in communication connection
with a central control unit 20. In principle, a wireless or
wired communication connection may be provided.
The central control unit 20 may comprise processing means (not
illustrated) and a database. The central control unit 20 may
further be connected to additional casting plants (not
illustrated).
The operation of the casting plant 4 according to Figure 1 is
described in greater detail below with reference to Figure 2.
Figure 2 is a flow chart of an embodiment of a method for
controlling a casting plant 4 according to the present invention.
In a first step 201, initially before the be4inning of the
production process, that is to say, before the casting process
of a first component 4, at least a first set process parameter
can be determined. The determination of the set process
parameter may be dependent in particular on the material 8, the
casting plant 4, the state of the casting plant 4, the mould
shape, the component 6 to be produced, etcetera.
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It will be understood that a plurality of set process parameters
may be determined. In particular at least one limit value for at
least one process parameter may be determined. Furthermore, at
least one set solidifying time may be predetermined. At least
one minimum set solidifying time and one maximum set solidifying
time may preferably be determined.
Furthermore, not only set parameters but also a formula for
determining the optimum solidifying time may preferably be
determined, in particular in accordance with the above-mentioned
criteria, the formula preferably being able to be dependent on a
set solidifying time, set process parameter and detected process
parameters. For example, individual conditions can be associated
with each other logically.
According to the embodiment explained in greater detail below,
there may be predetermined a minimum set temperature, a minimum
set solidifying time, a maximum set solidifying time and the
condition that the temperature progression is decreasing, the
individual connections being able to be associated with each
other logically.
The set temperature value may be, for example, in the range
between 350 C and 600 C in the case of aluminium as the material.
The minimum set solidifying time may be in the range between 80
seconds and 180 seconds. The maximum set solidifying time may be
in the range between 100 seconds and 250 seconds.
The determination of the at least one set process parameter or a
formula may be determined by the control device 14 of the
casting plant 4. However, a superordinate control device 20, for
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example, a central control unit 20 having a database for
determining the at least one set process parameter may
preferably be provided. The superordinate control device 20 may
particularly be configured to monitor and control a plurality of
casting plants.
In a subsequent step 202, the fluid material can be introduced
into the mould 10. At the same time, a time measuring device can
be started. For example, the time measuring device may be
started when the filling operation is started or when the
filling operation finishes.
In a subsequent step 203, the fluid material can cool and
solidify. At least one process parameter may be detected during
the casting process. In the present embodiment, the temperature
of the material in the mould 10 is continuously detected by a
sensor device 18. It will be understood that the temperature can
be detected continuously during the entire production process
and not only during the casting operation.
The control device 14 can particularly be configured to compare
the currently detected temperature of the material with the
optimum set temperature.
If the control device 14 establishes that the optimum set
temperature has been reached or the value has fallen below it,
it can initially further be investigated whether the temperature
progression is decreasing. Furthermore, it can additionally be
investigated whether the minimum set solidifying time has
already been exceeded. To this end, the value of the time
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measuring device can be compared with the minimum set
solidifying time.
If the conditions are complied with, the control unit 14 can
cause the mould 10 to be opened and the component 6 to be
removed in a step 204. After the component 6 has been removed,
the mould 10 can be closed again, the time measuring device can
be reset and the method can be continued in accordance with step
202.
An alternative removal condition may be reaching the maximum set
solidifying time. The value of the time measuring device may be
compared, preferably continuously, with at least the maximum set
solidifying time. Even if the temperature of the material has
not yet reached the set temperature, it is nevertheless possible
for the cast component 6 to be removed. In this instance, there
is a measurement error in all probability.
However, the mould 10 is not opened if, although the current
temperature of the material is below the set temperature, the
temperature progression is increasing. In the present embodiment,
the mould 10 is also not opened if, although the current
temperature of the material is below the set temperature, the
minimum set solidifying time has not yet been reached.
The last instances mentioned indicate a technical error. For
example, the detection device 18 may be defective. In this
instance, the mould 10 may initially be opened in step 204 after
the minimum or maximum set solidifying time has expired.
Subsequently, the production process may be interrupted or ended
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(step 205). Suitable measures for eliminating the technical
error may be taken.
