EP3814125B1 - Methods for operating a stamping press and stamping presses for being operated according to the methods - Google Patents

Description

technical field

The present invention relates to a method for operating a stamping press, stamping presses for operation according to the method and the use of such stamping presses to produce embossing for predetermined separation points in sheet metal surfaces according to the preambles of the independent patent claims.

State of the art

Highly complex and precise parts are manufactured on today's high-speed punching machines. In order to be able to produce such parts with a high cadence, a high degree of repeatability of the closing dimension of the tool is required. A change in the closing dimension on the tool has a negative impact on part accuracy.

In the event that only stamping and/or forming work is carried out, tools without stops are usually used. With these tools, the closing dimension essentially depends on the position of the upper tool part at the bottom dead center of the crank mechanism (BDC position). Important influencing variables for a change in the BDC position are the speed of the crank mechanism, the oil temperature (heating of the machine), the ambient temperature (changes over the course of the day) and the tool heating.

Out of EP 0 732 194 B1 it is known to measure the BDC position in a tool without a stop and to keep it constant by changing the ram position. This allows the most important influencing variables to be compensated for in a relatively simple manner.

In the event that precise embossing is carried out, for example with progressive dies, the tools are usually equipped with so-called fixed stops equipped. These fixed stops have the function of forcibly limiting the closing dimension under operating conditions. The press is inevitably clamped at the bottom dead center in order to ensure a stop contact of the fixed stops. The previously mentioned influencing factors of speed, oil temperature, ambient temperature and tool heating can significantly change the degree of stress during operation, with the result that the press is additionally heavily loaded with forces that are not involved in the actual process and apart from the fact that they are unnecessary Destroy energy, can lead to increased wear of the press.

From EP 0 732 194 B1 known solution is not applicable here, since the closing dimension is determined during operation independently of the degree of tension via the fixed stops and is always the same.

Accordingly, the problem arises that automated process control is hardly possible with such tools with fixed stops and it is essentially left to the skill and experience of the operator to control the process as energy-efficiently and with as little wear as possible.

Out of EP 0 353 479 A1 devices according to the preamble of claims 21 and 29 and methods according to the preamble of claims 1 and 9 are known for correcting the ram position in a stamping press with a tool with fixed stops depending on the maximum impact force of the fixed stops.

EP 0 554 501 A1 discloses devices and methods for correcting the closing dimension in a stamping press with fixed stops. Fixed stops arranged outside of the tool are adjusted in height with the help of piezo elements, and the press is thus clamped to a greater or lesser extent at the bottom dead center

Presentation of the invention

The task therefore arises of providing a technical solution which can remedy this situation.

This object is achieved by the method having the features of claims 1 and 9 and stamping presses having the features of claims 1 and 29 and the use according to claim 40.

According to these, a first aspect of the invention relates to a method for operating a stamping press, in particular with a tool with which embossings for predetermined separation points are produced in sheet metal surfaces.

The stamping press includes a ram that works against a preferably fixed platen. The position of the ram in relation to the clamping plate, i.e. the relative position of the upward and downward movement of the ram in relation to the clamping plate can be adjusted during normal operation. The ram carries a first part of the tool and the platen carries a second part of the tool. The two tool parts have mutually associated stop surfaces which, when the tool is completely closed, form one or more fixed stops for limiting the closing mass of the tool inside the tool.

According to the method according to the invention, when the punching press is operated as intended, the distance between the two tool parts or a parameter representing this distance, i.e. a parameter from which the distance between the two tool parts can be derived, at a specific point in the ram movement at which the tool is not completely closed, monitored and then changed the ram position depending on the monitoring result.

The tool is not completely closed in the sense of the claim if the closing dimension of the tool is not limited by the or one of the fixed stops, ie no associated stop surfaces of the two tool parts are in stop contact. This is independent of whether the tool is in deformation contact with the workpiece or not.

With the method according to the invention, an energy-efficient and low-wear process control is also possible with tools with fixed stops, independently of the skill and experience of the operator.

The distance between the two tool parts or the parameter representing this distance is preferably monitored at a point in the ram movement which is closer to bottom dead center than top dead center, preferably just before or just after bottom dead center. The closer this point at the bottom Dead center is, the more precisely the process can be managed.

In a first preferred variant of the method, the distance between the two tool parts or the parameter representing this distance is monitored at a point in the ram movement at which the tool is not in deformation contact with the workpiece, i.e. does not act on the workpiece, so that the ram does no work. This results in the advantage that the monitoring cannot be disturbed by any effects caused by the punching impact.

In an alternative, second preferred variant of the method, the distance between the two tool parts or the parameter representing this distance is monitored at a point in the ram movement at which the tool is in deformation contact with the workpiece, i.e. it acts on the workpiece, so that the ram does work done. This variant offers the advantage that the monitoring takes place under operating conditions that are very similar to the conditions at bottom dead center. This enables a particularly precise process control.

Depending on the stamping process, one or the other variant may be more preferable.

The movement of the ram is preferably generated via a crank or eccentric drive, in particular such that a 360° revolution of a crank or eccentric shaft is converted into a complete downward movement and a complete upward movement of the ram between an upper and a lower dead center of the ram movement. Such ram drives have become established in high-speed punching presses.

Correspondingly, with such stamping presses, it is preferred to determine the distance between the two tool parts or the parameter representing this distance at a specific angular position of the crank or To monitor the eccentric drive on which the tool is not completely closed, and then to change the ram position depending on the monitoring result. The angular position can be determined exactly and is therefore particularly suitable for determining the point of the ram movement at which the distance between the two tool parts or the parameter representing this distance is monitored.

The monitoring advantageously takes place at an angular position which is in a range of plus/minus 35° around the bottom dead center. It has been shown that this angular position range is particularly well suited for monitoring the distance between the two tool parts or the parameter representing this distance.

In a preferred embodiment of the method according to the invention, the distance between the two tool parts or the parameter representing this distance is kept constant at the specific point of the ram movement or at the specific angular position in normal operation by manually or automatically adjusting the ram position as a function of the monitoring result. This makes it possible to keep the degree of clamping of the press at bottom dead center essentially constant over the entire operation, regardless of the influencing variables of speed, oil temperature, ambient temperature and tool heating, so that uniform product quality can be ensured.

If the distance between the two tool parts or the parameter representing this distance is set to a specific value at the specific point of the ram movement or at the specific angular position, in particular to an empirically determined value at which a desired production result is achieved, and then by Adjustment of the ram position is kept constant at this value as a function of the monitoring result achieve optimal production results with minimum mechanical stress on the press with a high level of efficiency.

According to a preferred variant, it is also provided to monitor the distance between the two tool parts or a parameter representing this distance at several points of the ram movement, e.g. both shortly before and shortly after bottom dead center, and then the ram position as a function of this monitoring result to change.

A second aspect of the invention relates to a further method for operating a stamping press, in particular with a tool with which embossings for predetermined separation points are produced in sheet metal surfaces.

The stamping press comprises a ram which works against a preferably fixed platen and whose ram position relative to the platen can be adjusted during normal operation. The ram carries a first part of the tool and the platen carries a second part of the tool. The two tool parts have mutually associated stop surfaces which, when the tool is completely closed, form one or more fixed stops for limiting the closing mass of the tool inside the tool.

According to this method, when the punching press is operated as intended, at least one of the fixed stops is monitored for stop contact and the ram position is changed as a function of the monitoring result.

With this second method according to the invention, it is also possible to implement an energy-efficient and low-wear process control for tools with fixed stops, independently of the skill and experience of the operator.

With this method, the monitoring for impact contact can be carried out directly or indirectly, ie by detecting effects caused by the impact contact are caused (directly) or by parameters that indicate or represent a stop contact (indirectly).

Thus, according to a preferred embodiment of the second method, an electrical contact is made or closed by the contact of the respective stop surfaces, which electrical contact generates a contact signal that is used for monitoring.

In a first variant, one of the stop surfaces advantageously has two contacts for this purpose in at least one of the fixed stops, which are short-circuited by the other stop surface for generating the contact signal when there is a stop contact.

In another preferred variant, in at least one of the fixed stops, the two stop surfaces form a contact pair which is closed for generating the contact signal when there is a stop contact.

These direct monitoring variants using stop surfaces, which simultaneously represent electrical contacts, can be implemented in a simple manner and are robust and reliable.

In a further preferred embodiment of the second method, a deformation of a physicality of the tool or a tool area that takes place under the impact pressure, which or which provides one of the contact surfaces of a fixed stop, is detected to monitor the fixed stop for stop contact, e.g. by means of strain gauges and/or piezo elements.

In yet another preferred embodiment of the second method, a parameter representing the stop contact is monitored.

According to a preferred variant, this is done in such a way that physical entities formed by the two tool parts or carried by them are monitored, preferably without contact, for a relative position to one another that represents the stop contact, eg to a reference dimension, which is only reached when there is contact with the stop.

In a further preferred variant, one or more reference stops are monitored for stop contact, which are each formed by associated stop surfaces of the two tool parts and where the stop contact is made, the monitored fixed stop or stops also have stop contact. This is done, for example, in such a way that, as described above, an electrical contact is made or closed by the contact of the contact surfaces of the respective reference stop, which generates a contact signal, or that a deformation of a physical entity that occurs under the contact pressure, which one of the contact surfaces of the respective reference stop provides, is detected.

In the second method according to the invention, the movement of the ram is preferably generated via a crank or eccentric drive, in particular such that a 360° rotation of a crank or eccentric shaft results in a complete downward movement and a subsequent complete upward movement of the ram between an upper and a lower dead center of the ram movement is converted. Such ram drives have become established in high-speed punching presses.

In yet another preferred embodiment of the second method, the course of movement of the first tool part or the ram relative to the fixed press structure, relative to the clamping platen or relative to the second tool part is monitored in the area of the bottom dead center of the ram movement and the ram position is changed depending on the monitoring result .

In a preferred variant, this is done in such a way that the time or the angle of rotation of the crank or eccentric drive is monitored during which the first tool part or the ram is in the area of the bottom dead center of the ram movement, there is no relative movement with respect to the fixed press structure, with respect to the platen or with respect to the second tool part, and the ram position is changed as a function of this time or this angle of rotation. In this way, relatively simple and precise monitoring is possible.

In yet another preferred embodiment of the second method, the drive torque curve or the power consumption curve of the press drive is monitored in the area of the bottom dead center of the ram movement and the ram position is changed depending on the monitoring result.

According to a preferred variant, this is done in such a way that the time or the angle of rotation of the crank or eccentric drive is monitored during which the drive torque or the power consumption in the area of bottom dead center of the ram movement has a specific course or exceeds a specific threshold value, and the ram position is changed as a function of this time or this angle of rotation.

In another variant, the maximum value that the drive torque or the power consumption reaches in the area of the bottom dead center of the ram movement is monitored and the ram position is changed as a function of the monitoring result.

Such variants based on the drive torque profile or the power consumption profile of the press drive have the advantage that no sensors are required in the actual working area of the punch press, which is why they are very reliable.

In yet another preferred embodiment of the second method, during normal operation, the duration of the stop contact of one or more fixed stops is manually or automatically adjusted by adjusting the ram position as a function of the Monitoring result kept constant. This makes it possible to keep the degree of clamping of the press at bottom dead center essentially constant over the entire operation, independent of influencing variables such as speed, oil temperature, ambient temperature and tool heating, so that uniform product quality and efficient and low-wear operation can be guaranteed .

It is preferred that the ram position is set as a function of the monitoring result in such a way that a specific stop contact duration results, preferably the shortest possible stop contact duration. In this way, optimal production results can be achieved with a high degree of efficiency with minimal mechanical stress on the press.

In yet another preferred embodiment of the second method, the tool of the stamping press has a plurality of monitored fixed stops. During normal operation, a specific constellation of these monitored fixed stops is brought into stop contact, preferably automatically, by adjusting the ram position as a function of the monitoring result for each working stroke.

Preferably, the ram position is set as a function of the monitoring result in such a way that a fixed stop of the constellation that came into stop contact last is in stop contact for as short a time as possible. In this way, too, with such tools, optimum production results can be achieved with a high degree of efficiency with minimal mechanical stress on the press.

With the method according to the invention, embossings for predetermined separation points in sheet metal surfaces are advantageously produced with the tool according to the first and the second aspect of the invention, preferably predetermined separation points in sheet metal surfaces for container lids with tear-open or press-in tabs. In such applications the advantages of the method according to the invention come into play particularly clearly.

A third aspect of the invention relates to a first punch press for use in accordance with the method of the first aspect of the invention.

The stamping press comprises a preferably fixed platen and a ram which works against the platen. The ram position of the ram relative to the clamping plate is adjustable in normal operation. The ram carries a first tool part and the platen carries a second tool part. The two tool parts provide mutually associated stop surfaces which, when the tool is completely closed, form one or more fixed stops for limiting the closing dimension of the tool inside the tool. Such punching tools are typically used when high-precision embossing has to be produced, e.g. predetermined separation points in can end blanks.

The stamping press has devices for controlling the position of the ram, with which, when the stamping press is operated as intended, the distance between the two tool parts or a parameter representing this distance at a specific point in the ram movement at which the tool is not completely closed, as under the first aspect described according to the invention can be monitored and the ram position can be changed depending on the monitoring result.

As already mentioned, the tool is not completely closed in the sense of the claim if the closing dimension of the tool is not limited by the or one of the fixed stops, ie none of the assigned stop surfaces of the two tool parts are in stop contact. This is independent of whether the tool is in deformation contact with the workpiece or not.

With the punching press according to the invention, energy-efficient and low-wear production is also possible with tools with fixed stops, regardless of the skill and experience of the operator.

In a preferred embodiment of the stamping press, its devices for controlling the ram position are designed in such a way that the distance between the two tool parts or the parameter representing this distance can be monitored at a point in the ram movement which is closer to the bottom dead center of the ram movement than to the top dead center the same. This point is preferably just before or just after bottom dead center. The closer this point is to bottom dead center, the more precisely the process can be managed.

In a first variant, the devices for controlling the position of the ram are designed in such a way that the distance between the two tool parts or the parameter representing this distance can be monitored at a point in the ram movement at which the tool is not in deformation contact with the workpiece, i.e does not act on the workpiece, so that the ram does not do any work. This results in the advantage that a disturbance in the monitoring due to any effects caused by the work of the ram can be prevented.

In an alternative second variant of the device, the devices for controlling the ram position are designed in such a way that the distance between the two tool parts or the parameter representing this distance can be monitored at a point in the ram movement at which the tool is in deformation contact with the workpiece. So acts on the workpiece, so that the ram performs work. This variant offers the advantage that the monitoring can take place under operating conditions that Conditions at bottom dead center are very similar, making a particularly precise process control possible.

Depending on the stamping process performed on the stamping press, one variant or the other may be more preferable.

According to a preferred variant of the stamping press, the devices for controlling the ram position are designed in such a way that the distance between the two tool parts or a parameter representing this distance can be monitored both before and after the bottom dead center of the ram movement and then the ram position as a function of this Monitoring results can be changed.

The stamping press preferably has a crank or eccentric drive for generating the ram movement. A 360° rotation of a crank or eccentric shaft is converted into a complete downward movement and a complete upward movement of the ram between an upper and a lower dead center of the ram movement. Such stamping presses have established themselves for the production of stamped parts with a high cadence.

Accordingly, it is preferred with such punching presses to monitor the distance between the two tool parts or the parameter representing this distance at a specific angular position of the crank or eccentric drive at which the tool is not completely closed, and then to monitor the ram position as a function of that to change the monitoring result. The angular position can be determined exactly and is therefore particularly suitable for determining the point of the ram movement at which the distance between the two tool parts or the parameter representing this distance is monitored.

The devices for controlling the ram position are advantageously designed in such a way that they can be used to monitor the distance between the two tool parts to each other or to the parameter representing this distance at an angular position which is in a range of plus/minus 35° around the bottom dead center. It has been shown that this angular position range is particularly well suited for monitoring the distance between the two tool parts or a parameter representing this distance.

In yet another preferred embodiment of the first stamping press, the devices for controlling the position of the ram are designed in such a way that the distance between the two tool parts or the parameter representing this distance at the specific point of the ram movement or at the specific angular position in normal operation is adjusted by adjusting the ram position can be kept constant depending on the monitoring result. This makes it possible to keep the degree of clamping of the press at bottom dead center essentially constant over the entire operation, independent of influencing factors such as speed, oil temperature, ambient temperature and tool heating, so that uniform product quality and efficient, low-wear operation can be ensured .

The devices for controlling the ram position are advantageously designed in such a way that the distance between the two tool parts or the parameter representing this distance can be set to a specific value at the specific point of the ram movement or at the specific angular position, preferably to an empirically determined value Value at which a desired production result is achieved and can then be kept constant at this value in an automated manner by adjusting the ram position as a function of the monitoring result. With such punching presses according to the invention, optimal production results can be achieved with a high degree of efficiency with minimal mechanical stress on the press.

A fourth aspect of the invention relates to a further stamping press for operation according to the method according to the second aspect of the invention.

This second stamping press also includes a preferably stationary platen and a ram which works against the platen. The ram position of the ram relative to the clamping plate can also be adjusted during normal operation. The ram carries a first tool part and the platen carries a second tool part. The two tool parts provide mutually associated stop surfaces which, when the tool is completely closed, form one or more fixed stops for limiting the closing dimension of the tool inside the tool.

The stamping press has devices for controlling the ram position, with which at least one of the fixed stops of the tool can be monitored for abutment contact during normal operation of the stamping press and the ram position can be changed depending on the monitoring result.

As already mentioned, the tool is not completely closed in the sense of the claim if the closing dimension of the tool is not limited by the or one of the fixed stops, ie no associated stop surfaces of the two tool parts are in stop contact. This is independent of whether the tool is in deformation contact with the workpiece or not.

With the second punching press according to the invention, energy-efficient and low-wear production is also possible with tools with fixed stops, regardless of the skill and experience of the operator.

In a preferred embodiment of the second stamping press, the tool is designed in such a way that an electrical contact is made or closed by the contact of the respective stop faces which generates a monitoring contact signal for the devices for controlling the ram position.

In a first variant, one of the stop surfaces advantageously has two contacts for this purpose in at least one of the fixed stops, which are short-circuited by the other stop surface for generating the contact signal when there is a stop contact.

In another preferred variant, in at least one of the fixed stops of the tool, the two stop surfaces form a contact pair which is closed for generating the contact signal when there is a stop contact.

In a further preferred embodiment of the second stamping press, the tool and the devices for controlling the ram position are designed in such a way that deformation of a physicality of the tool or of a tool area that takes place under the impact pressure, which or which provides one of the contact surfaces of a fixed stop, is monitored of the fixed stop to the stop contact can be detected, in particular by means of strain gauges and/or piezo elements, and the ram position can be changed as a function of this.

In yet another preferred embodiment of the second stamping press, the devices for controlling the position of the ram are designed in such a way that a parameter representing the stop contact can be monitored.

In a preferred variant, the devices for controlling the ram position are designed in such a way that bodies formed by or carried by the two tool parts can be monitored, preferably without contact, for a relative position to one another that represents the stop contact, e.g. for a reference dimension that is only reached when the stop contact occurs becomes.

In a further preferred variant of the second stamping press, the tool and the devices for controlling the ram position are designed in such a way that one or more reference stops formed by associated stop surfaces of the two tool parts, with the stop contact of which the monitored fixed stop or stops have stop contact, are monitored for stop contact preferably in such a way that an electrical contact is made or closed by the contact of the contact surfaces of the respective reference stop, which generates a contact signal, or that a deformation of a physical entity occurring under the contact pressure, which one of the contact surfaces of the respective reference stop provides, is detected can.

The second stamping press preferably also has a crank or eccentric drive for generating the ram movement, with which a 360° rotation of a crank or eccentric shaft is converted into a complete downward movement and a complete upward movement of the ram between an upper and a lower dead center of the ram movement becomes. As already mentioned, such stamping presses have established themselves for the production of stamped parts with a high cadence.

In yet another preferred embodiment of the second stamping press, the devices for controlling the position of the ram are designed in such a way that the course of movement of the first tool part or the ram relative to the stationary press structure, relative to the clamping platen or relative to the second tool part is in the area of the bottom dead center of the ram movement can be monitored and the ram position can be changed depending on the monitoring result.

In a preferred variant, the devices for controlling the ram position are of this type designed so that the time or the angle of rotation of the crank or eccentric drive can be monitored during which the first tool part or the ram in the area of the bottom dead center of the ram movement does not move relative to the fixed press structure, to the clamping plate or to the second tool part carried out, and the ram position can be changed depending on this time or this angle of rotation. This allows for relatively easy and precise monitoring.

In yet another preferred embodiment of the second stamping press, the devices for controlling the ram position are designed in such a way that the drive torque curve or the power consumption curve of the crank or eccentric drive can be monitored in the area of the bottom dead center of the ram movement and the ram position as a function can be changed by the monitoring result.

According to a preferred variant, the devices for controlling the ram position are designed in such a way that the time or the angle of rotation of the crank or eccentric drive can be monitored during which the drive torque or the power consumption in the area of the bottom dead center of the ram movement follows a certain course has or exceeds a certain threshold value and the ram position can be changed depending on the monitoring result.

It is also preferred that the devices for controlling the ram position are designed in such a way that the maximum value that the drive torque or the power consumption reaches in the area of bottom dead center of the ram movement can be monitored and the ram position can be changed depending on the monitoring result.

Such on the drive torque curve or the power consumption curve of the press drive based monitoring devices have the advantage that they do not require sensors in the actual working area of the punch press, which is why they are very reliable.

In yet another preferred embodiment of the second stamping press, the devices for controlling the ram position are designed in such a way that, during normal operation, the duration of the stop contact of one or more fixed stops can be kept constant, preferably automatically, by adjusting the ram position as a function of the monitoring result. This makes it possible to keep the degree of clamping of the press at bottom dead center essentially constant over the entire operation, independent of influencing factors such as speed, oil temperature, ambient temperature and tool heating, so that uniform product quality can be ensured.

It is preferred that the devices for controlling the ram position are designed in such a way that the ram position can be adjusted depending on the monitoring result in such a way that a specific stop contact duration results, preferably the shortest possible stop contact duration. In this way, optimal production results can be achieved with a high degree of efficiency with minimal mechanical stress on the press.

In yet another preferred embodiment of the second stamping press, the tool of the stamping press has a plurality of monitored fixed stops and the devices for controlling the ram position are designed in such a way that, during normal operation, a specific constellation from these monitored fixed stops is preferably automatically generated by setting the ram position as a function of the Monitoring result can be brought into stop contact with each working stroke.

The devices for controlling the ram position are preferably designed in such a way that the ram position can be set as a function of the monitoring result in such a way that a fixed stop of the constellation that came into stop contact last is in stop contact for as short a time as possible. In this way, too, optimal production results can be achieved with a high degree of efficiency with minimal mechanical stress on the press.

A fifth aspect of the invention relates to the use of the inventive stamping presses according to the third and fourth aspects of the invention for producing embossing for predetermined separation points in sheet metal surfaces, preferably for predetermined separation points in sheet metal surfaces for container lids with a tear-open or press-in tab. The advantages of the invention are particularly evident in such uses.

Brief description of the drawings

• Fig. 1 eine erfindungsgemässe Stanzpresse mit einem Stanzwerkzeug mit Festanschlägen in der Vorderansicht; und
• die Figuren 2 bis 10 jeweils das Detail X aus Fig. 1 mit zugeordneter Stösselbewegungskurve bei verschiedenen erfindungsgemässen Ausführungsformen und Betriebsweisen der Stanzpresse.

Further preferred embodiments of the invention result from the dependent claims and from the following description based on the figures. show:

• 1 a punching press according to the invention with a punching tool with fixed stops in the front view; and
• the Figures 2 to 10 the detail X in each case 1 with associated ram movement curve in various embodiments and modes of operation of the punch press according to the invention.

Ways to carry out the invention

1 shows a highly abstracted inventive high-speed punching press 1 for the production of stamped parts with high-precision embossing for predetermined separation points in sheet metal surfaces, such as blanks for Container lid with tear-off or press-in tab, front view.

As can be seen, the press 1 has a fixed platen 3 and a ram 2 which works against the platen 3 . The position of the ram, ie the relative position of the up and down movement of the ram 2 in relation to the clamping plate 3, can be adjusted during normal operation.

The ram 2 carries an upper tool part 4 (first tool part according to the claims), which has a punch 9 with a punching mandrel 10 and a stamping projection 11 running around the punching mandrel 10 .

The clamping plate 3 carries a lower tool part 5 (second tool part according to the claims), which forms a support surface for the strip of material 13 to be processed and a die 12 for the punching mandrel 10 of the upper tool part 4 . The two tool parts 4 and 5 together form the stamping and embossing tool 4, 5 of the press 1. They each have stop bodies 6, 7, which provide mutually associated stop surfaces 6a, 7a, which when the tool 4, 5 is completely closed, provide fixed stops for the tool-internal limitation of the closing mass of the tool 4, 5 form.

The stamping press 1 has a crank drive 8 for generating the ram movement (represented symbolically with dashed lines), which converts a 360° rotation of a crankshaft into a complete downward movement and a subsequent complete upward movement of the ram 2 between a top dead center and a bottom dead center UT ram movement converted.

When the stamping press 1 is operating as intended, the material strip 13 to be processed is intermittently pushed through the press 1 from right to left by means of a strip feed (not shown).

Furthermore, the press 1 has a press controller (not shown) with devices for controlling the ram position.

In the Figures 2 to 10 are each based on the detail X 1 and an associated ram movement curve 15 for a rotation angle range of the crank drive from about 35° before bottom dead center UT to about 35° thereafter, various modes of operation and embodiments of the stamping press 1 according to the invention are explained.

The distances, the thickness of the strip material 13 and in particular also the height of the embossing projection 11 are shown significantly enlarged for better visibility.

At the in the Figures 2 to 4 illustrated first embodiment of the punch press 1 according to the invention and in figure 5 Illustrated second embodiment of the punching press 1 according to the invention, the press control is designed according to the invention in such a way that, during normal operation of the punching press 1, it measures the distance a, a1, a2, a3 between the two tool parts 4, 5 or a parameter b1, b2, b3 representing this distance , c can be monitored at a specific point P1, P2, P3 of the ram movement, at which the tool 4, 5 is not completely closed, and the ram position can be changed depending on the monitoring result, preferably in such a way that it is constant over the entire production operation Closing conditions of the tool 4, 5 are present at bottom dead center of the ram movement.

In this way, it is possible to largely compensate for the influence of variables influencing the closing dimension, such as mold and machine heating, ambient temperature and speed of the crank mechanism, and to ensure essentially identical mold closing conditions at bottom dead center over the entire operation.

In the first embodiment of the punch press 1 according to the Figures 2-4 has the lower stop body 7 in its center set back from the stop surface 7a on a contactless distance sensor 14, which in the intended operation of the press 1 to determine the distance from the stop surface 6a of the associated stop body 6 of the upper tool half 4 is used. In the present case, this sensor 14 is an inductive distance sensor or a laser distance sensor.

As shown in the illustration 2 can be seen in conjunction with the associated ram movement curve 15 shown next to it, the press ram 2 in the situation shown here - shortly after the punching and embossing process has taken place - is in the upward movement in a position which corresponds to a rotational angle position P1 of the crank mechanism of 35° after BDC (+35°) corresponds. In this position, the stop faces 6a, 7a of the stop bodies 6, 7 shown are at a distance a1 from one another. In this situation, the tool 4, 5 is not in deforming contact with the strip of material 13 and consequently does not perform any work either.

In the first mode of operation according to the invention of the first embodiment of the punching press 1 illustrated here, the press controller uses the sensor 14 to determine the distance a1 between the stop surfaces 6a, 7a or a reference distance, e.g. the distance b1 between the sensor 14 and the stop surface 6a of the upper stop body 6, and compares this with a target value.

This determination of the distance a1 or the reference distance b1 and comparing it with a target value corresponds to the claimed monitoring of the distance between the two tool parts or a parameter representing this distance (reference distance).

If a deviation from the setpoint is detected, the press control changes the ram position, in the present case in such a way that with continuous Monitoring the deviation from the setpoint is reduced or eliminated.

3 illustrates a second mode of operation according to the invention of the first embodiment of the stamping press 1. As can be seen in conjunction with the associated ram movement curve 15, the press ram 2 is in the illustrated situation in the downward movement - shortly before the stamping and embossing process - in a position which one Angle of rotation position P2 of the crank mechanism of 20° before UT (-20°) corresponds. In this position, the stop surfaces 6a, 7a of the stop bodies 6, 7 shown are at a distance a2 from one another or the sensor 14 is at a distance b2 from the stop surface 6a of the upper stop body 6. In this situation, the tool 4, 5 is not in deformation contact with the material strip 13 and consequently does not perform any work either. The second mode of operation of the punch press 1 according to the invention illustrated here differs from that in 2 illustrated only by the fact that here the distance a2 between the stop surfaces 6a, 7a or the reference distance b2 is determined in each case in the rotational angle position P2 of the crank drive (20° before BDC) and compared with a corresponding setpoint value. Monitoring the distance a2 between the two tool parts 4, 5 or a reference distance b2 representing this distance at the rotational angle position P2 shortly before the punching mandrel 10 and the embossing projection 11 hit the material strip 13 has the advantage that the acceleration forces acting on the system are very are similar to those in the bottom dead center, but there are still no system vibrations excited by the punching impact, which could interfere with the measurement. Accordingly, very reliable and precise monitoring is possible in this way.

4 illustrates a third mode of operation according to the invention of the first embodiment of the stamping press 1. As in conjunction with the associated ram movement curve 15, the press ram 2 is in the in 4 illustrated situation in the downward movement during the punching and embossing process in a position which corresponds to a rotational angle position P3 of the crank mechanism of 10 ° before the BDC (-10 °). In this position, the stop surfaces 6a, 7a of the stop bodies 6, 7 shown are at a distance a3 from one another or the sensor 14 is at a distance b3 from the stop surface 6a of the upper stop body 6. The punching mandrel 10 has already completely pierced the strip of material 13 and entered the die 12 and the embossing projection 11 has just begun to penetrate the strip of material 13 . Accordingly, in this situation the tool is in deformation contact with the material strip 13 and performs deformation work (embossing).

The third mode of operation of the punch press according to the invention illustrated here differs from that in 3 illustrated only by the fact that here the distance a3 between the stop surfaces 6a, 7a or the reference distance b3 is determined in each case in the rotational angle position P3 of the crank drive (10° before BDC) and compared with a corresponding setpoint value. Monitoring the distance a3 between the two tool parts 4, 5 or a reference distance b3 representing this distance at the rotational angle position P3 after the punching mandrel 10 has passed through the material strip 13 and while the embossing projection 11 has penetrated the material strip 13 has the advantage that the The total forces acting on the system are very similar to those that occur in ideal operation at bottom dead center. Accordingly, particularly reliable and precise monitoring is possible with this mode of operation.

The second embodiment of the punch press 1 according to figure 5 differs from the first embodiment according to the figures 2 , 3 and 4 in that the distance sensor 14 is not arranged in the lower stop body 7 is, but on an auxiliary carrier 16, and that with it the distance c between the sensor 14 and a reference surface 21 on the underside of the upper tool half 4 is determined. Like the reference distances b1, b2, b3 in the first embodiment of the stamping press 1, this reference distance c is a parameter representing the distance between the stop surfaces 6a and 7a of the stop bodies 6, 7 according to the claims. The rest of the structure of the stamping press 1 is identical to that according to the first embodiment and the sensor 14 is also an inductive distance sensor or a laser distance sensor in the present case.

As shown in the illustration figure 5 can be seen in conjunction with the associated ram movement curve 15 shown next to it, the press ram 2 is in the situation shown here (as already in the 2 situation shown) shortly after the punching and embossing process has taken place in the upward movement in a position which corresponds to a rotational angle position P1 of the crank mechanism of 35° after BDC (+35°). In this position, the stop surfaces 6a, 7a of the stop bodies 6, 7 shown are at a distance a from one another. In this situation, the tool is not in deforming contact with the strip of material 13 and consequently does not perform any work either.

In the mode of operation according to the invention of the second embodiment of the punching press 1 illustrated here, the press controller uses the sensor 14 to determine the distance a between the stop surfaces 6a, 7a or a reference distance, e.g. the distance c between the sensor 14 and the reference surface 21 on the underside of the upper tool half 4 and compares this with a target value.

This determination of the distance a or the reference distance c and comparing the same with a Target value corresponds to the claimed monitoring of the distance between the two tool parts or a parameter representing this distance (reference distance).

If a deviation from the target value is detected, the press controller changes the ram position, specifically in the present case in such a way that the deviation from the target value is reduced or eliminated with continuous monitoring.

At the in the figures 6 In the various embodiments of the punch press 1 illustrated in FIGS. 1 to 11, the press controller is designed according to the invention in such a way that it can be used to monitor at least one of the fixed stops for stop contact during normal operation of the punch press 1 and the ram position can be changed as a function of the monitoring result, preferably in such a way that over the entire production operation constant closing conditions of the tool 4, 5 are present at the bottom dead center of the ram movement.

In this way, it is also possible to largely compensate for the influence of variables affecting the closing dimension, such as tool and machine heating, ambient temperature and speed of the crank mechanism, and to ensure essentially identical mold closing conditions at bottom dead center UT over the entire operation.

As can be seen in conjunction with the associated ram movement curves 15, the press ram 2 is in the figures 6 to 11 illustrated situations each in the bottom dead center UT of its movement. In this position, the stop surfaces 6a, 7a of the stop bodies 6, 7 shown are in contact with one another and thus form a fixed stop that limits the tool closing dimension.

How further from the associated ram movement curves 15 can be seen is in the figures 6 to 11 illustrated situations the point Pk1, at at which the stop contact between the two stop surfaces 6a, 7a occurs, each at 5° before BDC (-5°) and the point Pk2 at which the stop contact is canceled again, each at 5° after BDC (+5°). Accordingly, there is stop contact within a rotation angle range of 10° (plus/minus 5° around UT). At the current speed of the crank drive 8 of the press 1 of 1000 rpm, there is abutment contact for a period of time t of 1.6 ms.

In the 6 illustrated third embodiment of the punch press 1 differs from the first embodiment according to the Figures 2 to 4 only in that it has a press control which implements another mode of operation of the press according to the invention. In this embodiment, the press control does not determine the distance between the stop surfaces 6a, 7a or a reference distance at a specific angular position P1, P2 or P3, but rather uses the sensor 14 to determine the angular positions Pk1 and Pk2 or the angular range or the time period t without contact , between which or within which there is no longer any distance between the stop surfaces 6a, 7a (stop contact) or between which or within which a specific minimum distance between the stop surfaces 6a, 7a is fallen below or reached. For this purpose, the press control evaluates the reference distance d between the sensor 14 and the stop surface 6a of the upper stop body 6, which represents the stop contact of the stop surfaces 6a and 7a or the determined minimum distance.

The determined rotational angle positions Pk1, Pk2, rotational angle ranges and/or time periods t are compared with setpoint values. If the press control detects a deviation from the target value, it changes the ram position in such a way that the deviation from the target value is reduced or eliminated with continuous monitoring.

The fourth embodiment of the punch press 1 according to 7 differs from the second embodiment according to figure 5 in that it does not have a distance sensor 14 for determining a reference distance representing the distance between the stop surfaces 6a, 7a, but rather two strain gauges 17 or piezoelectric elements with which a deformation D of the lower stop body 7 when the upper stop body 6 is pressed with its stop surface 6a against the Stop surface 7a of the lower stop body 7 can be determined. It also has a press control which implements another mode of operation of the press 1 according to the invention.

In the present case, the press controller uses the strain gauges 17 or piezoelectric elements to determine the rotational angle positions Pk1 and Pk2 or the rotational angle range or the time period t between which or within which contact there is contact between the stop surfaces 6a, 7a. The determined rotational angle positions Pk1, Pk2, rotational angle ranges and/or time periods t are compared with setpoint values. If the press control detects a deviation from the target value, it changes the ram position in such a way that the deviation from the target value is reduced or eliminated with continuous monitoring.

The fifth embodiment of the punch press 1 according to 8 differs from the second embodiment according to figure 5 in that it has no strain gauges 17 or piezo elements for determining a stop contact between the stop surfaces 6a, 7a, but these stop surfaces 6a, 7a are formed by electrical contact bodies 18a and 18b, which together form a contact pair 18a, 18b, which is used to generate a Contact signal KS is closed at stop contact. It also has a press control which implements another mode of operation of the press according to the invention.

In this embodiment, the press control uses the pair of contacts 18a, 18b to determine the rotary angle positions Pk1 and Pk2 or the rotary angle range or the time period t between which or within which there is abutment contact between the abutment surfaces 6a, 7a. The determined rotational angle positions Pk1, Pk2, rotational angle ranges and/or time periods t are compared with setpoint values. If the press control detects a deviation from the target value, it changes the ram position in such a way that the deviation from the target value is reduced or eliminated with continuous monitoring.

The sixth embodiment of the punch press 1 according to 9 differs from the fifth embodiment according to FIG 8 in that the stop surface 7a of the lower stop body 7 is formed by two separate electrical contact bodies 19a and 19b, while the stop surface 6a of the upper stop body 6 is formed by a single connected contact body 20. The contact bodies 19a and 19b form two contacts 19a, 19b, which are short-circuited by the contact body 20 when there is abutment contact and thereby generate a contact signal KS.

The press control is identical here to that of the fifth embodiment of the punch press described above. With the aid of the contacts 19a, 19b, it determines the rotary angle positions Pk1 and Pk2 or the rotary angle range or the time period t between which or within which there is abutment contact between the abutment surfaces 6a, 7a. The determined rotational angle positions Pk1, Pk2, rotational angle ranges and/or time periods t are compared with setpoint values. If the press control detects a deviation from the target value, it changes the ram position in such a way that the deviation from the target value is reduced or eliminated with continuous monitoring.

In the 10 illustrated seventh embodiment of the punch press 1 differs from the second embodiment according to figure 5 only in that it has a press control which implements another mode of operation of the press according to the invention. In this embodiment, the press controller does not use sensor 14 to determine the distance between stop surfaces 6a, 7a or a reference distance at a specific rotary angle position, but instead uses sensor 14 and reference surface 21 to determine the rotary angle positions without contact on the underside of upper tool half 4 Pk1 and Pk2 or the angle of rotation range or the time period t between which or within which the upper tool half 4 does not perform any vertical movement due to abutment contact of the abutment surfaces 6a, 7a (movement standstill). For this purpose, the press controller evaluates the change over time in the reference distance c between the sensor 14 and the reference surface 21 in the area around the bottom dead center UT.

The determined rotational angle positions Pk1, Pk2, rotational angle ranges and/or time periods t are compared with setpoint values. If the press control detects a deviation from the target value, it changes the ram position in such a way that the deviation from the target value is reduced or eliminated with continuous monitoring.

While the present application describes preferred embodiments of the invention, it is to be understood that the invention is not limited thereto and may be otherwise embodied within the scope of the following claims.

Claims (40)

1. Method of operating a stamping press (1) with a ram (2) which operates against a bolster plate (3), in particular a fixed bolster plate (3), and whose ram position relative to the bolster plate (3) can be adjusted in the intended use, the ram (2) carrying a first die part (4) and the bolster plate (3) carrying a second die part (5), wherein the two die parts (4, 5) provide associated stop faces (6a, 7a) which, when the die (4, 5) is fully closed, form one or more fixed stops within the die for limiting the closing dimension of the die (4, 5),
   characterized in that, in the intended use of the stamping press (1), the distance (a, a1, a2, a3) between the die parts (4, 5) or a parameter (b1, b2, b3, c) representing said distance at a specific point (P1, P2, P3) of the ram movement, at which the die (4, 5) is not fully closed, is monitored, and the ram position is changed as a function of the monitoring result.
2. The method according to claim 1, wherein the distance(a, a1, a2, a3) between the two die parts (4, 5) or the parameter (b1, b2, b3, c) representing said distance is monitored at a point (P1, P2, P3) of the ram movement which is closer to the bottom dead center (UT) of the ram movement than to the top dead center of the ram movement, in particular shortly before or shortly after the bottom dead center (UT).
3. The method according to claim 2, wherein the distance (a, a1, a2) of the two die parts (4, 5) from each other or the parameter (b1, b2, c) representing said distance is monitored at a point (P1, P2) of the ram movement at which the die (4, 5) is not in deformation contact with the workpiece (13).
4. The method according to claim 2, wherein the distance (a3) between the two die parts (4, 5) or the parameter (b3) representing said distance is monitored at a point (P3) of the ram movement at which the die (4, 5) is in deformation contact with the workpiece (13).
5. The method according to one of the preceding claims, wherein the ram movement is generated via a crank drive or an eccentric drive (8).
6. The method according to claim 5, wherein the distance (a, a1, a2, a3) of the two die parts (4, 5) from one another or the parameter (b1, b2, b3, c) representing said distance is monitored at a specific angular position (P1, P2, P3) of the crank drive or the eccentric drive (8) at which the die (4, 5) is not completely closed, and the ram position is changed as a function of the monitoring result.
7. The method according to claim 6, wherein the angular position (P1, P2, P3) is within a range of plus/minus 35° around the bottom dead center (UT).
8. The method according to one of the preceding claims, wherein the distance (a, a1, a2, a3) between the two die parts (4, 5) or the parameter (b1, b2, b3, c) representing said distance is kept constant at the specific point (P1, P2, P3) of the ram movement or at the specific angular position (P1, P2, P3) in the intended use by setting the ram position as a function of the monitoring result.
9. Method of operating a stamping press (1) with a ram (2) which operates against a bolster plate (3), in particular a fixed bolster plate (3), and whose ram position relative to the bolster plate (3) can be adjusted in the intended use, the ram (2) carrying a first die part (4) and the bolster plate (3) carrying a second die part (5), wherein the two die parts (4, 5) provide associated stop faces (6a, 7a) which, when the die (4, 5) is fully closed, form one or more fixed stops within the die for limiting the closing dimension of the die (4, 5), wherein the ram movement of the stamping press (1) is generated via a crank drive or an eccentric drive (8),
   characterized in that, in the intended use of the stamping press (1), at least one of the fixed stops is monitored for stop contact, wherein the angle of rotation positions (PK1, PK2) of the crank shaft or the eccentric shaft of the stamping press between which the stop contact exists, the angle of rotation of the crank shaft or the eccentric shaft of the stamping press within which the stop contact exists and/or the time period (t) within which the stop contact exists are determined and are compared with target values, and the ram position is changed as a function of the monitoring result.
10. The method according to claim 9, wherein an electrical contact (18a, 18b; 19a, 19b, 20) is made or closed by the contact of the associated stop faces (6a, 7a), which generates a contact signal for monitoring the contact.
11. The method according to any one of claims 9 to 10, wherein a deformation (D) of a body (7), which provides one of the contact surfaces (7a) of a fixed stop, taking place under the stop pressure is detected for monitoring the fixed stop for stop contact.
12. The method according to one of claims 9 to 11, wherein a parameter (c, d, v, M, P) representing the stop contact is monitored.
13. The method according to claim 12, wherein bodies (6, 6a, 14; 4, 14, 21) formed by the two die parts (4, 5) or carried by them are monitored, in particular without contact, for a relative position (c; d) to one another representing the stop contact.
14. The method according to one of claims 12 to 13, wherein one or more reference stops formed by associated stop faces of the two die parts, at the stop contact of which the monitored fixed stop or stops have stop contact, are monitored for stop contact, in particular in such a way that an electrical contact is made or closed by the contact of the stop surfaces of the respective reference stop, in particular in such a way that the contact of the stop faces of the respective reference stop makes or closes an electrical contact which generates a contact signal, or that a deformation of a body, which provides one of the contact surfaces of the respective reference stop, taking place under the stop pressure, is detected.
15. The method according to one of claims 9 to 14, wherein the relative movement (v) of the first die part (4) or of the ram (2) with respect to the fixed press structure, the bolster plate (3) or the second die part (5) is monitored in the region of the bottom dead center (UT) of the ram movement, and the ram position is changed as a function of the monitoring result.
16. The method according to claim 15, wherein the time (t) or the angle of rotation of the crank drive or the eccentric drive (8) is monitored, during which the first die part (4) or the ram (2) does not perform any relative movement against the fixed press structure, the bolster plate (3) or the second die part (5) in the region of the bottom dead center (UT) of the ram movement, and the ram position is changed as a function of the monitoring result.
17. The method according to one of claims 9 to 16, wherein the drive torque characteristic (M) or the power consumption characteristic (P) of the press drive (8) is monitored in the region of the bottom dead center (UT) of the ram movement, and the ram position is changed as a function of the monitoring result.
18. The method according to one of claims 9 to 17, wherein, in the intended use, the duration (t) of the stop contact of one or more fixed stops is kept constant, in particular automatically, by adjusting the ram position as a function of the monitoring result.
19. The method according to one of claims 9 to 18, wherein the die of the stamping press has several monitored fixed stops and, in the intended use, a specific constellation of these monitored fixed stops is brought into stop contact in each working stroke, in particular automatically, by setting the ram position as a function of the monitoring result.
20. The method according to one of the preceding claims, wherein the die (4, 5) is used to produce stampings for predetermined separation points in sheet metal surfaces, in particular predetermined separation points in sheet metal surfaces for container lids with tear-off or press-in tabs.
21. Stamping press (1) for operation in accordance with the methods according to one of claims 1 to 8, comprising a bolster plate (3), in particular a fixed bolster plate (3), and a ram (2) which acts against the bolster plate (3) and whose ram position relative to the bolster plate (3) can be adjusted in the intended use, wherein the ram (2) carries a first die part (4) and the bolster plate (3) carries a second die part (5), wherein the two die parts (4, 5) provide associated stop faces (6a, 7a) which, when the die (4, 5) is completely closed, form one or more fixed stops within the die for limiting the closing dimension of the die (4, 5),
    characterized in that the stamping press (1) has devices for controlling the ram position, by means of which, in the intended use of the stamping press (1), the distance (a, a1, a2, a3) between the two die parts (4, 5) or a parameter (b1, b2, b3, c) representing said distance at a specific point (P1, P2, P3) of the ram movement at which the die (4, 5) is not completely closed can be monitored, and the ram position can be changed as a function of the monitoring result.
22. Stamping press (1) according to claim 21, wherein the devices for controlling the ram position are configured such that the distance (a, a1, a2, a3) of the two die parts (4, 5) from each other or the parameter (b1, b2, b3, c) representing said distance can be monitored at a point (P1, P2, P3) of the ram movement which is closer to the bottom dead center (UT) of the ram movement than to the top dead center of the ram movement, in particular shortly before or shortly after the bottom dead center (UT).
23. The stamping press (1) according to claim 22, wherein the devices for controlling the ram position are configured such that the distance (a, a1, a2) between the two die parts (4, 5) or the parameter (b1, b2, c) representing said distance can be monitored at a point (P1, P2) of the ram movement at which the die (4, 5) is not in deformation contact with the workpiece (13).
24. The stamping press (1) according to claim 22, wherein the devices for controlling the ram position are configured such that the distance (a3) between the two die parts (4, 5) or the parameter (b3) representing said distance can be monitored at a point (P3) of the ram movement at which the die (4, 5) is in deformation contact with the workpiece (13).
25. The stamping press (1) according to one of claims 21 to 24, wherein the stamping press (1) has a crank drive or eccentric drive (8) for generating the ram movement.
26. The stamping press (1) according to claim 25, wherein the devices for controlling the ram position are configured such that the distance (a, a1, a2, a3) between the two die parts (4, 5) or the parameter (b1, b2, b3, c) representing said distance can be monitored at a specific angular position (P1, P2, P3) of the crank drive or eccentric drive (8) at which the die (4, 5) is not completely closed, and the ram position can be changed as a function of the monitoring result.
27. The stamping press (1) according to claim 26, wherein the devices for controlling the ram position are configured such that the monitoring can take place at an angular position (P1, P2, P3) in a range of plus/minus 35° around the bottom dead center (UT).
28. The stamping press (1) according to one of claims 21 to 27, wherein the devices for controlling the ram position are configured such that, in the intended use, the distance (a, a1, a2, a3) between the two die parts (4, 5) or the parameter (b1, b2, b3, c) at the specific point (P1, P2, P3) of the ram movement or at the specific ram position (P1, P2, P3) can be kept constant by adjusting the ram position as a function of the monitoring result.
29. Stamping press for operation according to the methods of one of claims 9 to 20, comprising a bolster plate (3), in particular a stationary bolster plate (3), and a ram (2) which acts against the bolster plate (3) and whose ram position relative to the bolster plate (3) can be adjusted in the intended use, the ram (2) carrying a first die part (4) and the bolster plate (3) carrying a second die part (5), the two die parts (4, 5) providing associated stop faces (6a, 7a) which, when the die (4, 5) is completely closed, form one or more fixed stops within the die for limiting the closing dimension of the die (4, 5), wherein the stamping press (1) has a crank drive or an eccentric drive (8) for generating the ram movement,
    characterized in that the stamping press (1) has devices for controlling the ram position, with which at least one of the fixed stops can be monitored for stop contact in the intended use of the stamping press (1), wherein the angle of rotation positions (PK1, PK2) of the crank shaft or the eccentric shaft of the stamping press between which the stop contact exists, the angle of rotation of the crank shaft or the eccentric shaft of the stamping press within which the stop contact exists and/or the time period (t) within which the stop contact exists are determined and are compared with target values, and the ram position can be changed as a function of the monitoring result.
30. The stamping press (1) according to claim 29, wherein the die (4, 5) is configured such that the contact of the stop faces (6a, 7a) of one or more fixed stops establishes or closes one or more electrical contacts (18a, 18b; 19a, 19b, 20) which generate a contact signal (KS) for monitoring purposes.
31. The stamping press (1) according to one of claims 29 to 30, wherein the die (4, 5) is configured such that a deformation (D) of a body (7), which provides one of the contact faces (7a) of a fixed stop, taking place under the stop pressure can be detected for monitoring the fixed stop for stop contact, in particular by means of strain gauges (17) and/or piezo elements.
32. The stamping press (1) according to any one of claims 29 to 31, wherein the devices for controlling the ram position are configured such that a parameter (c, d, v, M, P) representing the stop contact can be monitored.
33. The stamping press (1) according to claim 32, wherein the devices for controlling the ram position are configured such that bodies (6, 6a, 14; 4, 14, 21) formed by or carried by the two die parts (4, 5) can be monitored, in particular without contact, for a relative position (c; d) to one another representing the stop contact.
34. The stamping press according to one of claims 32 to 33, wherein the devices for controlling the ram position are configured such that one or more reference stops formed by respectively associated stop faces of the two die parts, at the stop contact of which the monitored fixed stop or stops have stop contact, can be monitored for stop contact, in particular in such a way that the contact of the stop faces of the respective reference stop establishes or closes an electrical contact which generates a contact signal, or that a deformation of a body which takes place under the stop pressure and which provides one of the contact surfaces of the respective reference stop can be detected.
35. The stamping press (1) according to one of claims 29 to 34, wherein the devices for controlling the ram position are configured such that the course of the relative movement (v) of the first die part (4) or of the ram (2) relative to the fixed press structure, the bolster plate (3) or the second die part (5) can be monitored in the region of the bottom dead center (UT) of the ram movement, and the ram position can be changed as a function of the monitoring result.
36. The stamping press (1) according to claim 35, wherein the devices for controlling the ram position are configured such that the time (t) or the angle of rotation of the crank drive or eccentric drive (8) can be monitored, during which the first die part (4) or the ram (2) does not perform a relative movement in the region of the bottom dead center (UT) of the ram movement with respect to the stationary press structure, the bolster plate (3) or the second die part (5), and the ram position can be changed as a function of the monitoring result.
37. The stamping press (1) according to one of claims 29 to 36, wherein the devices for controlling the ram position are configured such that the drive torque curve (M) or the power consumption curve (P) of the crank drive or eccentric drive (8) can be monitored in the region of the bottom dead center (UT) of the ram movement and the ram position can be changed as a function of the monitoring result.
38. The stamping press (1) according to one of claims 29 to 37, wherein the devices for controlling the ram position are configured such that, in the intended use, the duration (t) of the contact of one or more fixed stops can be kept constant, in particular automatically, by setting the ram position as a function of the monitoring result.
39. The stamping press according to one of claims 29 to 38, wherein the die of the stamping press has a plurality of monitored fixed stops and the devices for controlling the ram position are configured such that, in the intended use, a specific constellation of these monitored fixed stops can be brought into stop contact, in particular automatically, by setting the ram position as a function of the monitoring result at each working stroke.
40. Use of the stamping press (1) according to one of claims 21 to 39 for the production of stampings for predetermined separation points in sheet metal surfaces, in particular for predetermined separation points in sheet metal surfaces for container lids with tear-off or press-in tab.

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