WO2012110590A1

WO2012110590A1 - Electrically driven press, and pressing method that can be carried out with said press

Info

Publication number: WO2012110590A1
Application number: PCT/EP2012/052671
Authority: WO
Inventors: Alex Wehrli
Original assignee: Osterwalder Ag
Priority date: 2011-02-16
Filing date: 2012-02-16
Publication date: 2012-08-23

Abstract

The invention relates to a press and to a method for pressing a material by means of said press. According to the invention, the following steps are carried out prior to starting the pressing process: determining the torque time curve M(t) of the electric motor of the press during a given pressing cycle of the press; determining the current effective value (current quadratic average value) QMW_aof the torque time curve M(t) of the electric motor for the given pressing cycle as a fourth parameter; and determining the expected current electric motor end temperature T_endathat corresponds to said current effective value on the basis of the current effective value QMW_aof the torque time curve M(t), by means of interpolation or extrapolation for example, using previously determined data pairs (QMW; T_end) which are stored in the storing unit and each of which includes an effective value QMW of a torque time curve and an expected end temperature T_endthat is assigned to said effective value, and the result of said determination is displayed by means of the display unit. The invention allows the prevention of an unplanned standstill of a press during the pressing operation, said standstill being caused by an accumulation of heat in an electric motor, without having to resort to an expensive larger electric motor with lower dynamics.

Description

Electrically driven press and thus feasible pressing process

The invention relates to an electrically driven press as well as to a pressing method that can be carried out for pressing a

Material. The material may be e.g. around a solid to be deformed (hot deformation or cold deformation) or a powder for producing a compact (hot pressing or cold pressing) with possibly.

then sintering act.

Such a press includes: a) a punch assembly and a die assembly, between which material to be pressed is locatable; and b) an electric motor, by means of which the punch arrangement and the die arrangement are movable relative to one another and can be pressed against one another along a press axis during a press cycle.

Such a pressing process has the following steps for each pressing cycle:

51) placing material to be pressed between the punch assembly and the die assembly;

52) moving the punch assembly and the die assembly toward each other by means of the electric motor along a press axis;

53) pressing the punch assembly and the die assembly against each other by means of the electric motor, wherein the material is pressed;

S4) moving the punch assembly and the die assembly away from each other along a press axis by means of the electric motor;

S5) removing the pressed material from the press; and Repeating the pressing cycle or steps S1) to S5).

From JP 2010 240 655 a pressing method is known in which the temporal torque curve of an electric motor is determined for a pressing cycle of the press; and determining the root mean square (RMS) value of the torque curve of the electric motor for the pressing cycle.

During a pressing cycle, the electric motor converts electrical energy into both mechanical energy and thermal energy. Especially during the pressing of the material a lot of energy is needed for the forming and / or compaction. In this case, the stamp assembly moves with the stamp only slightly (quasi-static part of the pressing cycle). For the electric motor, this means that in its windings high currents occur at a given voltage and that the rotor moves with its windings only at very low speed (practically standstill of the rotor). In this phase of the press cycle, a lot of resistive heat is generated in the motor windings. Gradually then increases the total temperature of the electric motor and its windings and his

Surfaces up to a respective final temperature at which just as much heat is dissipated by heat conduction and / or heat radiation from Moror. Nevertheless, in many practical applications, where many process-specific pressing cycles take place in succession in a press, this final temperature of some part (windings or surface) of the part

Electric motor reached only after a certain number of such pressing cycles. Depending on the process, this final electric motor temperature can be reached faster or slower on the one hand, and on the other hand, this can be reached after a certain time reached final temperature below or above a maximum allowable electric motor operating temperature at which at least longer exceeding damage to the engine occur.

In such thermally inert electrical drives, which are used in particular in the form of servomotors, the final temperature of the engine is reached only after some time, possibly only after several hours. The maximum permissible final temperature or maximum permissible operating temperature of a servomotor may not

be crossed, be exceeded, be passed. To protect the engine are the windings

Assigned sensors which detect an exceeding of the maximum permissible operating temperature and then shut down the electric motor and thus the pressing operation via the press or motor control.

Now, in such a press, a new pressing operation, i. Press cycle, set up and programmed, this maximum allowable operating temperature may not be reached until after hours, and the press then unexpectedly shuts off. Such an unplanned downtime is undesirable and disturbs the production process.

When setting up the press, the expert does not know by means of his conventional methods whether and when this maximum permissible

Operating temperature (critical temperature, motor limit temperature) is achieved by an electric motor. He can therefore not take any countermeasures.

It would be conceivable at first glance, at the beginning

described press simply to use a larger electric motor, which is generously dimensioned compared to the recorded during a press cycle in the pressed material press energy and / or has sufficient cooling to easily derive the resulting in the windings of the electric motor heat loss in an extreme load operation.

This extreme load operation results in an electric motor when operated at standstill, i. is operated without rotation of the rotor. Then both the mechanical torque and the current in the

Windings maximum. If the electric motor thus operated is not sufficiently cooled, it may be damaged.

The maximum permanently generated torque at which the electric motor does not overheat, the so-called standstill torque, would then have to be greater than that during a sufficiently large and / or sufficiently cooled electric motor used in the press for pressing Press cycle occurring permanent maximum pressing torque. In other words, with such an electric motor, one could in principle permanently press without the motor overheating.

However, such a luxurious (over) dimensioning of the press electric motor has two major disadvantages.

First, larger electric motors have greater inertia. Consider the ratio M _max / TM between the maximum torque M _max and the moment of inertia TM of the electric motor rotor, which represents the maximum angular acceleration of the rotor. This value decreases with a scale-true enlargement of an electric motor. Larger electric motors therefore have worse dynamics than smaller ones

Electric motors with the same proportions. Since the moment of inertia of the electric motor provides the largest contribution to the total moment of inertia of an electric motor spindle unit, an electric motor spindle drive with a generously dimensioned electric motor thus also has worse dynamics than an electric motor spindle drive with a smaller one

dimensioned electric motor.

Second, with a larger electric motor, the cost of producing the motor itself and the cost of it are as well

Regulator assemblies significantly higher than a smaller electric motor.

The invention is therefore based on the object to avoid a caused by a heat accumulation in an electric motor unplanned shutdown of a press during the pressing operation without the just

to have to bear the disadvantages described.

The invention is based on the recognition that in a given electric motor system, such as e.g. a servomotor in a given engine environment with a defined ambient temperature,

Motor cooling, etc., after a sufficiently long time, ie after a sufficiently long continuous operation (continuous operation) or after a sufficiently large number of operating cycles (quasi-continuous operation), a stable End temperature Tend (limit temperature) is reached and that this

End temperature is a function of the quadratic time average QMW of the time course M (t) of the engine torque.

The quadratic time average of the QMW (Root Mean Square, RMS) is calculated as follows:

10

For continuous signals:

Here, the function f (t) is the time course of the engine torque M (t) and the times t1 and t2 are the beginning or the end of a pressing cycle during which the material is pressed.

Discretized and solved numerically:

QMW (moment) (M _! ² * A ti + M ₂ ² * A t ₂ + + M _n ² * A t _n ) * l / t, ₍

In this way, it is possible to assign to each such calculated value QMW of an electric motor operating cycle, which is uniquely determined by a specific time curve M (t) of the engine torque, an end temperature T _{en of} this electric motor system assigned to this value QMW. From the knowledge of the time course M (t) of the engine torque can therefore be determined from the determination of this curve M (t) during one or a few operating cycles of the engine this mean value QMW and thus the engine end temperature T _en d for a continuous or predict quasi-continuous continuous operation of the engine, which in turn with the maximum permissible operating temperature T _max (critical temperature,

Electric motor limit temperature) of the engine can be compared.

The invention is therefore based on the object to avoid a caused by a heat accumulation in an electric motor unplanned shutdown of a press during press operation, without having to accept the disadvantages just described.

To achieve this object, the invention provides a press of the type described above, which is characterized by c) a memory unit in which a plurality of data pairs (QMW; Tend) are stored, each of which is based on a given

Press cycle of the press for given material and with given

relate temporal torque curve of the electric motor and each containing a pair of mutually associated parameters QMW and T _en d, of which

the first parameter QMW is the effective value (root mean square) of the torque curve of the electric motor for the given pressing cycle; and

the second parameter T _en d is the (asymptotic) end temperature (equilibrium temperature) of the electric motor against which the

Operating temperature (winding temperature) of the electric motor strives to continue repeating the given press cycle;

- And a third parameter T _{max is} stored, which is the maximum operating temperature of the electric motor (limit temperature), which may not be exceeded; d) a torque determining unit for determining the time course of torque of the electric motor during a pressing cycle; e) an effective value determination unit for determining the effective value QMW (quadratic mean value) of the temporal

Torque curve M (t) of the electric motor at the given press cycle; and f) a parameter data processing unit for processing data groups containing the first parameter QMW, the second parameter Tend and the third parameter T _max .

According to the invention, the method described at the outset is characterized by processing of data groups which determine the thus determined current effective value QMW _a (current root mean square) of the temporal torque curve M (t) of the electric motor as fourth

Parameter, the stored RMS value QMW (stored square mean value) of the temporal torque curve of the

Electric motor as the first parameter, the final temperature T _en d

(Equilibrium temperature) of the electric motor as a second parameter and the maximum operating temperature T _{max of} the electric motor (limit temperature) as a third parameter, wherein the processing of the data groups starting from the current effective value QMW _a (current square

Mean value) of the temporal torque curve M (t) the current effective temperature corresponding to this current effective temperature T _en da of the electric motor stored in the memory unit, previously determined data pairs (QMW; T _en d), each having an effective value QMW a temporal torque curve and a associated with this

End temperature Tend, e.g. is determined by interpolation or extrapolation and the result of this determination is displayed by means of the display unit.

When processing the data groups, one uses the group of data pairs (QMW; T _en d) which, after a sufficiently long operation of the electric motor, has reached the final temperature T _en d of the electric motor as a function of the mean square of the time curve M (t) of the motor torque of the particular electric motor defined in a particular press. The course M (t) of the developed for a special pressing process Motor torque is determined for a press cycle, for example, and the corresponding value QMWa specific to this actual pressing operation is determined therefrom. From the data pairs (QMW; T _en d), the value Q _en corresponding to the value Q MW _a is then determined. This value T _en da is then compared with the value T _max and the result of this comparison is displayed. If T _en da is less than T _max , the operation of the press can be continued indefinitely with this time course of the engine torque. If T _en da is equal to or greater than T _max , the operator of the press must take precautions. For example, it may either limit the number of repetitive press cycles, ie after this limited number of press cycles give the motor a sufficiently long break to cool down, or it may track the time M (t) of the engine torque and thus QMW _{a of} each of the press cycles change that T _{en is} always less than T _max , ie every number of press cycles.

The invention thus enables better utilization of a screw press electric motor over the entire range of use of the press with high dynamics of the rotor-spindle assembly of the same

Press drive.

In the case of the press according to the invention, a further plurality of data pairs (N; T _N ) are also stored in the storage unit, which in each case relate to a repeatedly performed given press press cycle for a given material and with a given press cycle

relative torque curve or given quadratic averaged torque curve (QMW) of the electric motor and each containing a pair of mutually associated parameters, of which the first parameter (N) is the number of consecutively executed pressing cycles and the second parameter (T _N ) the (instantaneous) Temperature of the electric motor which reaches the operating temperature (winding temperature) of the electric motor after repeating the given pressing cycle N times; the press additionally having g) a press cycle counting unit for counting press cycles since the start of the press. Conveniently, the press h) includes a display unit for displaying a result of parameter processing performed in the parameter data processing unit; and / or i) an input unit for

Entering a pressing method parameter. Such a parameter may be, for example, the time curve M (t) of the engine torque during an entire pressing cycle, ie during steps S1) to S5). Further parameters are, for example, the parameters QMW, T _en d and T _max mentioned above.

During the processing of the data groups, the specific expected actual end temperature (T _en da) of the electric motor is preferably compared with the maximum operating temperature (T _max ) of the electric motor stored in the memory unit and the result of this comparison displayed by means of the display unit.

These procedures allow the operator of the press, at the beginning of a press use of the press for the serial production of a large number of articles of pressed material, to make a prediction whether or not the critical temperature T _{max is reached} during the working operation.

In the inventive method

expediently also carried out the following further steps:

Counting the N press cycles since the start of the press, or entering the number N of consecutive scheduled press cycles into the parameter data processing unit;

Processing of further data sets corresponding to the determined current effective value (QMWa), the number of successive press cycles performed as the first parameter (N) and that after N

Press cycles reached current temperature of the electric motor as the second parameter (T _Na ) included; and

Displaying a result of the processing of the further data groups. Preferably, in the processing of the further data groups on the basis of the count value N, successive successes have occurred so far

Press cycles or based on the input number N of planned consecutive pressing cycles with the respective given temporal torque curve M (t) corresponding to this current count reached current temperature (T _Na ) of the electric motor by means of the memory unit stored in the further data pairs (N; T _N ) eg determined by interpolation or extrapolation and displayed the result of this determination by means of the display unit.

Particularly preferred are in the processing of the other

Data groups the specific reached actual temperature (T _Na ) of the

Electric motor with the stored in the memory unit Maximai- operating temperature (T _max ) of the electric motor compared and displayed the result of this comparison by means of the display unit.

These procedures allow the operator of the press in the event that the reaching / exceeding of the critical temperature T _max and thus an automatic shutdown of the electric motor during the labor input is expected, at the beginning of a labor input of the press for the serial production of a large number of Articles made of pressed material to make a prediction when (ie after which time or after how many chronologically juxtaposed pressing cycles) the critical temperature T _{max is reached} during the labor input.

A particularly advantageous embodiment of the method is characterized in that, when i) the particular expected current

End temperature (T _en da) of the electric motor is smaller than the maximum operating temperature (T _max ) of the electric motor, the press through the

Parameter data processing unit for an indefinite number N of press cycles is released without restriction, preferably this release is displayed by the display unit; and that, when ii) the determined expected actual end temperature (T _en da) of the electric motor is equal to or greater than the maximum operating temperature (T _ma x) of the electric motor, the press through the parameter data processing unit is not released for an indefinite number N of press cycles, and preferably this non-release is indicated by the display unit.

Preferably, in the method, if ii) the determined expected actual end temperature (T _end a) of the electric motor is equal to or greater than the maximum operating temperature (T _max ) of the electric motor and the press by the parameter data processing unit for a indefinite number N of press cycles is not released, the parameter data processing unit determines, by means of the further data pairs (N; T _N ), a maximum number N _max of press cycles according to which the

_End temperature (T _end ) of the electric motor is less than its maximum operating temperature (T _max ).

Alternatively or additionally, in the method, if ii) the determined expected final temperature (T _end a) of the electric motor is equal to or greater than the maximum operating temperature (T _max ) of the electric motor and the press through the parameter data processing unit is not released for an indeterminate number N of pressing cycles, the parameter data processing unit uses the data pairs (QMW; T _end ) to determine a maximum effective value QMW _max (root mean square) of the torque curve M (t) of the electric motor for a pressing cycle with which the final temperature (T _end ) of the electric motor is always, ie for an unlimited number N of pressing cycles, less than its maximum operating temperature (T _max ).

Starting from this maximum value QMW _max , it is particularly advantageous if the parameter data processing unit for determining an acceptable maximum effective value QMW _max ^* the temporal

Torque curve M (t) of the previously used, containing the steps S1) to S5) trial-press cycle gradually (gradually) changed by the duration of step S2) for moving the punch assembly and the die assembly towards each other and / or the duration of step S4) for moving the punch assembly and the die assembly away from each other gradually (gradually) so often increased and by means of the torque-determining unit during the respective gradually changed Press cycle occurring temporal torque curve M (t) of the electric motor respectively determined and by means of the effective value determination unit, the corresponding effective value QMW this particular time

Torque curve M (t) of the electric motor at the respective gradually changed pressing cycle determined until the thus determined corrected

Press cycle has a corrected effective value QMW _max * of its corrected torque curve M (t) * for which the final temperature (T _end ) of the electric motor is always, ie for an unlimited number N of pressing cycles, less than its maximum operating temperature (T _max ) , As a result, the electric motor has more time for cooling during each pressing cycle, so that it strives towards a lower _end temperature T _end .

In this modification of the time profile M (t), it is particularly advantageous if the parameter data processing unit for determining an acceptable maximum effective value QMW _max * the temporal

Torque curve M (t) of the previously used, the steps S1) to S5) containing sample pressing cycle gradually (gradually) changed by the duration of step S3) and the temporal torque curve M (t) during the step S3) for Pressing the punch assembly and the die assembly against each other unchanged. As a result, the previously optimized and technologically relevant part of the pressing cycle for the quality of the pressed material is not changed. Thus, only the purely commercially relevant times of steps S1) and S2) before the technologically relevant unchanged step S3) and also the purely commercially relevant times of steps S4) and S5) after the technologically relevant unchanged step S3) are used for the possible change ,

Other advantages, features and applications of the invention will become apparent from the following, not limiting

A description of examples with reference to the drawing, in which:

Fig. 1 is a graph showing the final temperature T _en d of a given electric motor in a given press as a function of the quadratic time average QMW of the torque curve M (t) of the electric motor; Fig. 2 is another diagram which corresponds to the diagram of Fig. 1 and contains as further process parameters the maximum permissible operating temperature of the electric motor (limit temperature, critical temperature, threshold value); and

3 is another graph showing five temperature histories TN (temperature transits) of the given electric motor as a function of the number N of press cycles performed, each of the five temperature histories being valid for a respective QMW of the press cycle.

In Fig. 1 is a diagram showing the final temperature T _en d of a given electric motor in a given press as a function of the quadratic time average QMW of the torque curve M (t) of the electric motor. In the range of QMW = 80Nm to QMW = 130Nm, there is a practically linear relationship between that achieved after sufficiently long operation with a sufficient number of repeated press cycles

Final temperature T _en d of the windings of the electric motor. The diagram was empirically determined on the basis of the measuring points shown by testing for a given press with a given servo-electric drive over a longer period of time with always the same pressing cycles and measuring the temperature in the motor winding. Every measuring point in the diagram

represents those for the respective root mean square QMW

characteristic asymptotic end temperature T _en d of the motor winding. For the determination of each point of a measurement series, so many (identical) press cycles ("strokes") were applied under force until the temperature had reached a constant final value.From a representative press cycle ("stroke"), the time series M (t) of

Determined torque and from the root mean square value QMW determined.

This characteristic curve (T _en d; QMW) can be used by the press manufacturer for each type of press, ie each servo-electric drive in a specific type

The "press environment" is determined by the boundary conditions of the servo-electric drive, such as, for example, the type of engine cooling, ambient temperature, and obstructions Heat dissipation and / or heat radiation through machine panels, etc. This characteristic is then stored by the press manufacturer in the press control.

Preferably, a plurality of such characteristics (T _en d; QMW) are determined by the press manufacturer, suitably for a given set of constraints, as described above. All of these characteristic curves (T _en d; QMW) _RB which are specific for certain boundary conditions R B are then conveniently stored in the press control.

2 shows a diagram which corresponds to the diagram of FIG. 1 and as a further process parameter the maximum permissible operating temperature of the electric motor T _max (limit temperature, critical

Temperature). Conveniently, this maximum permissible motor winding operating temperature T _{max is} stored in the press control.

It can be seen from the diagram of FIG. 2 that the maximum permissible operating temperature of the electric motor T _max = 105 ° C. is not reached even with repeated cycles of pressing cycles, each with a mean square value QMW <130 Nm. This means that virtually infinite number of such press cycles with QMW <130 Nm can be carried out in succession, and the end temperature T _en d of the motor winding always remains below T _max .

In Fig. 3, another diagram is shown, the five

Temperature curves T _N (temperature responses) of the given electric motor as a function of the number N performed pressing cycles shows, the five temperature curves T _N (V), T _N (W), T _N (X), T _N (Y) and T _N (Z ) the respective root mean square values QMW (V), QMW (W), QMW (X), QMW (Y) and

QMW (Z) correspond to the pressing cycle. The larger QMW, the steeper the temperature profile T _N. In the present case we have QMW (V)> QMW (W)> QMW (X)> QMW (Y)> QMW (Z) and thus correspondingly a decreasing slope of the corresponding temperature curves in the order T _N (V), T _N ( W), T _N (X), T _N (Y), T _N (Z). In addition, the diagram contains the maximum permissible operating temperature of the electric motor T _max (limit temperature, critical temperature). Expediently, these temperature profiles T _N and the maximum operating temperature T _{max are} stored in the press control.

It can be seen from the diagram of FIG. 3 that for the quadratic mean values QMW (V), QMW (W), QMW (X) of the curve M (t) of the engine torque after a particular number N _max (V), N _max (W), Nmax (X) of repeated press cycles or after a certain period of operation (duration of one press cycle x number of press cycles) t _max (V), t _max (W), t _max (X) of the press the maximum permissible operating temperature T _max is reached, which leads to (typically automatic) shutdown of the servo-electric drive and thus to a standstill of the press. Furthermore it can be seen that for the root mean square values QMW (Y) and QMW (Z) of the curve M (t) of the

Motor torque even with an infinite number of repeated

Press cycles the maximum permissible operating temperature T _{max is} not reached, whereby the (typically automatic) shutdown of the servo-electric drive and thus the standstill of the press can be avoided.

With the stored temperature transitions T _N (QMW), in the event that the maximum permissible operating temperature T _{max is} reached at some point, as is known, for example, from the information in the diagrams in FIG. 1 and in FIG. 2, for a given servo drive press Constellation and at a given QMW of M (t) of the servo drive are predicted or estimated by how many N _max consecutively and in time

consecutive press cycles, ie after which operating time T _{max of} the press the maximum permissible operating temperature T _{max is} reached.

This can be responded to in various ways. First, one can limit the operation of the press to a number of press cycles and thus pressed (reshaped or compacted) articles that is less than the number N _max . Secondly, one can change M (t) such that QMW becomes smaller to a sufficient extent that the maximum allowable

Operating temperature T _{max is} never reached. In this change in the time course M (t) of the engine torque is preferably the torque or press force-intensive phase of the respective press cycle unchanged, so that the product quality of the pressed article also remains unchanged. Instead, the torque- or presskraft- weak phases of the pressing cycle using the relationship (Tendi QMW) of Fig. 1 are sufficiently prolonged that always T _en d <T _{max is} met. Thus, just enough cooling time is provided during each pressing cycle to sufficiently compensate for the temperature rise of the electric motor during each pressing cycle during the entire pressing operation.

A particularly preferred embodiment of the invention is characterized in that data groups are processed, which include, inter alia, a current, ie newly determined torque RMS value (fourth parameter) with previously ("in stock") determined torque RMS values (first parameter) the expected current end temperature of the electric motor is determined by means of the data pairs (QMW; T _en d) stored in the memory unit, an example of such data pairs (QMW; T _en d) being shown in FIG. 1, and possibly the current count value corresponding reached actual end temperature of the electric motor by means of the data stored in the memory unit data pairs (N; T _N ) is determined, wherein in Fig. 3 examples of such data pairs (N; T _N ) are shown.

The following is an example of a typical procedure according to the invention. 1 . It is assumed that the described characteristic (T _en d; QMW) is stored in the controller.

2. Immediately after or even during setup, a measuring stroke is run, i. go through a representative press cycle.

3. The engine torque curve M (t) is automatically determined.

4. From this, the QMW of the moment M (t) is calculated, and from the characteristic curve (T _en d; QMW), the final temperature T _en d is determined for this purpose.

5. This value T _en d is the maximum allowable

Operating temperature (critical temperature) T _max compared.

6. If the determined value T _en d is at or below the value T _max , the installer receives the consent to start production.

7. If the determined value T _en d above the value T _max , there are several options: a) the operator starts the press in the knowledge that after a certain time the critical temperature T _{max is} reached. This time is displayed to the operator both as time and as number of press cycles (strokes). Also included are stamp cleaning times, handling times and other loss times, which give the engine time to cool down. These loss times are used in calculating the QMW of the moment

included. b) The software proposes to change the pressing cycle (stroke). A distinction is made here between the dynamic component (approach and departure of the punch) of the moment M (t) and the quasi-static portion (contact and pressing of the material) of the moment M (t).

Option A: The software iteratively calculates an optimal default value (time) for the high acceleration phases within a press cycle during which no pressing is performed.

By increasing the time interval of these phases, two effects are achieved:

1) the cycle time is longer, this goes directly into the QMW;

2) the acceleration values and thus the torque values are reduced, the QMW decreases.

This default value is selected such that the final temperature T _en d * corresponding to the newly determined QMW ^* is theoretically just below the maximum permissible temperature T _max .

Variant B:

The software calculates with which minimum press speed (approach and departure of the punch) or maximum press holding time (contacting and pressing of the material) is to be driven so that the maximum permissible temperature T _{max is} not exceeded. Where:

The higher the press speed, the lower the QMW of the moment.

The shorter the press holding time, the lower the QMW of the moment.

The software can also combine the different variants resp. determine their influence with a weighting. This is how the most efficient measure can be defined.

Claims

claims

1 . A press for pressing a material, comprising: a) a punch assembly and a die assembly, between which material to be pressed is locatable; b) an electric motor, by means of which the punch arrangement and the die arrangement are movable relative to one another and can be pressed against one another along a press axis during a press cycle; characterized by: c) a memory unit in which a plurality of data pairs (QMW; Tend) are stored, each of which is assigned to a given

Press cycle of the press for given material and with given

the first parameter QMW is the effective value (root mean square) of the torque curve M (t) of the electric motor at the given pressing cycle; and

2. Press according to claim 1, characterized in that in the memory unit are also stored: a further plurality of data pairs (N; T _N ), each on a repeatedly performed given press cycle of the press for a given material and with a given temporal torque curve or given quadratic averaged torque curve QMW of

Electric motor and each containing a pair of mutually associated parameters, of which the first parameter N, the number of

successively executed pressing cycles and the second parameter T _{N is} the (instantaneous) temperature of the electric motor reaching the operating temperature (winding temperature) of the electric motor after repeating the given pressing cycle N times; and characterized by g) a press cycle counting unit for counting press cycles since the start of the press.

3. A press according to claim 1 or 2, characterized by h) a display unit for displaying a result of parameter processing performed in the parameter data processing unit; and / or i) an input unit for inputting a pressing method parameter.

4. A method for pressing a material by means of a press according to one of claims 1 to 3, wherein the method for each

Press cycle has the following steps:

54) moving the punch assembly and the die assembly away from each other along a press axis by means of the electric motor;

55) removing the pressed material from the press; and

Repeat the pressing cycle or steps S1) to S5), as well as

Determining the temporal course of torque M (t) of the electric motor during a given pressing cycle of the press; and

Determining the current effective value QMW _a (root mean square) of the temporal torque curve M (t) of the electric motor for the given pressing cycle as the fourth parameter, characterized by

Processing of data groups which determine the thus determined current effective value QMW _a (current quadratic mean) of the temporal

Torque curve M (t) of the electric motor as a fourth parameter, the stored RMS value QMW (stored quadratic mean) of the temporal torque curve of the electric motor as a first parameter, the final temperature Tend (equilibrium temperature) of the electric motor as second parameter and the maximum operating temperature T _{max of} the electric motor (limit temperature) as the third parameter, wherein wherein during processing of the data groups starting from the current effective value QMW _{a of} the temporal torque curve M (t) corresponding to this current effective value expected current end temperature Tenda of the electric motor by means of previously determined data pairs (QMW; T _en d) stored in the memory unit, which each contain an effective value QMW of a temporal torque curve and an expected final temperature Tend associated therewith, eg determined by interpolation or extrapolation, and the result of this determination by means of the display unit is shown.

5. The method according to claim 4, characterized in that when processing the data groups the specific expected current

End temperature T _en da of the electric motor with the stored in the memory unit maximum operating temperature T _{max of} the electric motor is compared and the result of this comparison is displayed by means of the display unit.

6. The method according to claim 4 or 5, characterized by:

Processing further data sets corresponding to the determined current effective value QMWa, which contain the number of consecutively executed pressing cycles as the first parameter N and the actual temperature of the electric motor reached after N pressing cycles as the second parameter T _Na ; and

Displaying a result of the processing of the further data groups.

7. The method according to claim 6, characterized in that when processing the further data groups based on the count of N successive successive pressing cycles or starting from the

inputted number N of planned consecutive pressing cycles with the respective given temporal torque curve M (t) the actual temperature T _{Na of} the electric motor corresponding to this current count is determined by means of the further data pairs (N; T _N ) stored in the memory unit, eg by interpolation or extrapolation, and the result of this determination is displayed by means of the display unit.

8. The method according to claim 7, characterized in that when processing the further data groups, the specific current temperature reached T _{Na of} the electric motor with the in the storage unit

stored maximum operating temperature T _{max of} the electric motor

is compared and the result of this comparison is displayed by means of the display unit.

9. Method according to one of claims 5 to 8, characterized in that, if i) the specific expected current

End temperature T _en da of the electric motor is smaller than the maximum operating temperature T _{max of} the electric motor, the press through the

Parameter data processing unit for an indefinite number N of press cycles is released without restriction, preferably this release is displayed by the display unit; and that, when ii) the determined expected actual end temperature T _en da of the electric motor is equal to or greater than the maximum operating temperature T _max of

Electric motor is the press is not released by the parameter data processing unit for an indefinite number N of pressing cycles, preferably this non-release is displayed by the display unit.

10. The method according to claim 9, characterized in that, when ii) the determined expected current end temperature T _en da of

Electric motor is equal to or greater than the maximum operating temperature T _{max of} the electric motor and the press through the

Parameter data processing unit for an indefinite number N of Press cycles is not released, the parameter data processing unit by means of the further data pairs (N; T _N ) a maximum number N _max of

Press cycles determined according to which the final temperature T _en d of the electric motor is smaller than its maximum operating temperature T _max .

1 1. A method according to claim 9 or 10, characterized in that, if ii) the determined expected final temperature T _en da of the electric motor is equal to or greater than the maximum operating temperature T _{max of} the electric motor and the press through the

Parameter data processing unit for an indeterminate number N of press cycles is not released, the parameter data processing unit by means of the data pairs (QMW; T _en d) a maximum effective value QMW _max (root mean square) of the temporal torque curve M (t) of the

Electric motor determined for a pressing cycle, with the final temperature T _en d of the electric motor always, ie for an unlimited number N of pressing cycles, less than its maximum operating temperature T _max .

12. The method of claim 1 1, characterized in that the parameter data processing unit for determining an acceptable maximum effective value QMW _max ^* the temporal torque curve M (t) of the previously used, the steps S1) to S5) containing sample pressing cycle gradually (Gradually) changing by increasing the duration of step S2) to move the punch assembly and the die assembly towards each other and / or the duration of step S4) to move the punch assembly and the die assembly away from each other gradually (gradually) and so on by means of the torque-determining unit taking place during the respective gradually changed pressing cycle temporal

Determined torque curve M (t) of the electric motor respectively and determined by the rms value determination unit, the corresponding effective value QMW this specific time curve M (t) of the electric motor at the respective gradually changed pressing cycle until the thus determined corrected pressing cycle a corrected effective value QMW _max ^* corrected temporal torque curve M (t) ^* , for which the final temperature T _en d of the electric motor is always, ie for an unlimited number N of pressing cycles, less than its maximum operating temperature T _max .

13. The method according to claim 12, characterized in that the parameter data processing unit for determining an acceptable maximum effective value QMW _max ^* the temporal torque curve M (t) of the previously used, the steps S1) to S5) containing sample pressing cycle gradually ( gradually) by changing the duration of step S3) and the temporal torque curve M (t) during step S3)

Pressing the punch assembly and the die assembly against each other unchanged.