DE102022100935A1 - Method and punching machine for determining a punch placement position of a punch of the punching machine - Google Patents

Abstract

A method according to the invention for determining a punch placement position (z0) of a punch (5) of a punching machine (1), which has a machine body (2) with a die (3) and a punch holder (4) which can be moved in a z-direction in the machine body (2) at right angles to the die (3) and has a punch (5) held thereon for punching a workpiece (6) lying against the die (3), comprises the following method steps: - extending the punch holder (4) in z- Direction in order to place the punch (5) on the die designed as a blind die (3`) or on a workpiece (6), without punching it, and then to expand the machine body (2) elastically by the punching force of the punch (5) acting between the punch holder (4) and the blind die (3`) or workpiece (6); - at a first punching position (z1), in which the machine body (2) is expanded, measuring an associated, first punching force (F1) of the punch (5), and determining the punch placement position (z0) in which the punch (5) touches the dummy die (3`) or the workpiece (6) when the punch holder (4) is extended, based on the measured first punching force (F1) and an expansion characteristic (12) of the machine body (2).

Description

The invention relates to a method for determining a punch placement position of a punch of a punching machine, which has a machine body with a die and a punch holder that can be moved in a z-direction in the machine body at right angles to the die, with a punch held thereon for punching a workpiece resting on the die. The invention also relates to a punching machine suitable for carrying out the method.

For the automated replacement of the punch from the punch holder, e.g. when starting up the punching machine or when replacing a linear amplifier, the punch holder must be moved to a specified punch changing position with great accuracy. The punch changing position is also used to determine an offset value for referencing the hydraulic z-axis of the punching machine.

The adjustment of the stamp changing position is typically carried out by a user via a mechanical distance measurement using gauge blocks. In this case, a drive of the stamp holder is energized in order to move the stamp holder. When the punch changing position is reached, the drive is switched off and the punch holder is braked. When braking the punch holder, unforeseeable positioning errors occur that are greater than the required tolerance for the punch changing position. For a more precise setting of the changing position, the setting process must therefore be repeated several times if necessary. In addition, the user of the punching machine is endangered by the manual use of gauge blocks when checking the position of the punch change, for example if the punch holder or other components of the punching machine release themselves from a set blockage. Therefore, additional adjustment devices are required to avoid endangering the measuring user.

In contrast, it is the object of the present invention to specify a method for the automated determination of a punch placement position and the punch changing position and to provide a punching machine suitable for carrying out the method.

• - Ausfahren der Stempelhalterung in z-Richtung, um den Stempel auf die als Blindmatrize ausgebildete Matrize oder auf ein Werkstück, ohne dieses zu stanzen, aufzusetzen und nachfolgend den Maschinenkörper durch die zwischen Stempelhalterung und Blindmatrize oder Werkstück wirkende Stanzkraft des Stempels elastisch aufzuweiten;
• - an einer ersten Stempelposition, in welcher der Maschinenkörper aufgeweitet ist, Messen einer zugehörigen, ersten Stanzkraft des Stempels, und
• - Bestimmen der Stempelaufsetzposition, in welcher der Stempel beim Ausfahren der Stempelhalterung auf die Blindmatrize oder das Werkstück aufsetzt, anhand der gemessenen ersten Stanzkraft und einer Aufweitungskennlinie des Maschinenkörpers.

According to the invention, this object is achieved in the method mentioned at the outset by the following method steps:

• - Extension of the punch holder in the z-direction in order to place the punch on the die designed as a blind die or on a workpiece without punching it, and then to expand the machine body elastically by the punching force of the punch acting between the punch holder and the blind die or workpiece;
• - at a first punch position in which the machine body is expanded, measuring an associated, first punching force of the punch, and
• - Determination of the punch placement position in which the punch touches the blind die or the workpiece when the punch holder is extended, based on the measured first punching force and an expansion characteristic of the machine body.

According to the invention, the punch (punching tool) is blocked by a dummy die or a workpiece of known workpiece thickness, so that no punching takes place. The dummy die is either completely closed, or its die opening is designed or installed rotated in such a way that the stamp cannot enter the die opening. The punch is extended and initially rests on the dummy die or on the workpiece, which then expands elastically as the machine body is extended further by the punching force of the blocked punch acting between the punch holder and dummy die or workpiece. If the stamp touches the dummy die or the workpiece, no forces act on the stamp, so that the associated stamp placement position cannot be determined directly by means of a force measurement. The first punching force of the punch measured at the first punch position can be assigned to a characteristic point of the expansion characteristic of the machine body; Starting from the measured characteristic point, the widening characteristic results in the force-free punch placement position in which the punch touches the dummy die or the workpiece when the punch holder is extended.

The punch change position of the punch holder, in which the punch holder has a predetermined change position distance from the die, can be determined using the determined punch placement position, a given punch length by which the punch protrudes in the z-direction beyond the punch holder, and, if necessary, the workpiece thickness. In the case of a punch placed on the dummy die, the punch changing position of the punch holder corresponds to the determined punch placement position minus the difference between the specified distance between alternate positions and the punch length, and for the case of a punch placed on the workpiece, the determined punch placement position minus the difference between the specified distance between alternate positions and the length of the punch plus the workpiece thickness. The punch is preferably returned to the determined punch changing position or an offset value is calculated for referencing the hydraulic z-axis of the punching machine. If the punch in the punch holder is exchanged for another punch with a different punch length, the inter-position distance changes accordingly, which can be taken into account automatically.

A manual re-measurement with additional gauge blocks or other measuring devices by a user of the punching machine is not necessary according to the invention. This also eliminates the need to brake the stamp holder, which is associated with manual re-measuring. The setting of the punch change position can thus be automated and with increased accuracy. It is also possible to perform the adjustment of the punch changing position during operation of the punching machine as part of the diagnosis.

In a variant of the method, an associated, second punching force of the punch is measured at at least one other, second punching position of the punch, in which the machine body is expanded to a different extent compared to the first punching position, and the expansion characteristic of the punch is determined on the basis of the measured first and second punching force and the associated punching positions Machine body determined. With this variant of the method, the punch placement position and the punch change position can be determined without having to first determine the expansion characteristic of the machine body.

In another variant of the method, the punch placement position is determined using the measured first punching force, the associated punch position and a previously known expansion characteristic of the machine body.

The punch holder is preferably moved hydraulically in order to provide the respective punching force.

In a further aspect, the invention also relates to a punching machine suitable for carrying out the method, having an elastically expandable machine body with a die, a punch holder that can be moved in a z-direction in the machine body at right angles to the die and with a punch held thereon for punching a punch lying against the die Workpiece, sensors for measuring the punching force of the punch acting between the punch holder and a dummy die or a non-punched workpiece at at least one punch position, and a control device designed to carry out the method according to the invention.

In a preferred embodiment of the punching machine according to the invention, the control device has a memory in which an expansion characteristic of the machine body is stored.

• 1a-1e schematisch eine erfindungsgemäße Stanzmaschine in einer Anfangsposition (1a) und in einer Stempelwechsellage (1b) einer Stempelhalterung, in zwei unterschiedlichen Aufweitungslagen eines Maschinenkörpers der Stanzmaschine (1c, 1d) und in einer Stempelaufsetzposition eines Stempels der Stempelhalterung (1e), jeweils in einem Längsschnitt; und
• 2 eine Aufweitungskennlinie des Maschinenkörpers in Abhängigkeit des Stempelhubs.

Further advantages of the invention result from the description and the drawing. Likewise, the features mentioned above and those detailed below can each be used individually or collectively in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for the description of the invention. It shows:

• 1a-1e schematically a punching machine according to the invention in an initial position ( 1a ) and in a stamp changing position ( 1b ) a punch holder, in two different expansion positions of a machine body of the punching machine ( 1c , 1d ) and in a stamp setting position of a stamp of the stamp holder ( 1e ), each in a longitudinal section; and
• 2 an expansion characteristic of the machine body as a function of the punch stroke.

In the 1a The punching machine 1 shown has a machine body 2 with a die 3 and a punch holder (punch holder) 4 which can be moved in the machine body 2 at right angles to the die 3 in a z-direction and has an exchangeable punch 5 held at the bottom for punching a workpiece 6 resting on the die 3 ( Workpiece thickness d) on.

The machine body 2 is C-shaped with a lower and an upper, horizontal machine arm 2a, 2b and can therefore be expanded elastically in the z-direction. The die 3 is attached to the upper side of the lower machine arm 2a. The upper machine arm 2b carries a hydraulic drive 7 on the underside with a lifting rod 8 that can be moved in the z-direction and to the lower rod end of which the punch holder 4 is attached in order to move the punch holder 4 together with the punch 5 in the z-direction. The punch length by which the punch 5 protrudes downwards in the z-direction beyond the punch holder 4 is denoted by WZL.

A control device 9 controls the stroke of the lifting rod 8 or the stamp holder 4 in order to move the stamp 5 with its free, lower stamp end to a stamp position z _S in each case. The stamp position z _S is preferred measured for the stamp holder 4 compared to an upper mechanical fixed stop, here merely as an example the underside 10 of the upper machine arm 2b. A sensor 11 is arranged on the drive train of the drive 7, here only by way of example on the punch holder 4, which measures the punching force F exerted by the punch 5 on the die 3 in each case at a punch position z _S .

In 1b the punch holder 4 is shown in a punch change position z _WL in which the punch holder 4 has a predetermined change position distance d _WL to the upper side of the die 3 . The stamp 5 can only be exchanged in or out of the stamp holder 4 in the stamp holder 4 in this stamp changing position z _WL .

• Zuerst wird die Matrize 3 gegen eine Blindmatrize 3' ausgetauscht (1b), die der Stempel 5 in z-Richtung nicht durchgreifen kann. Dann wird die Stempelhalterung 4 in z-Richtung ausgefahren, um den Stempel 5 auf die Blindmatrize 3` aufzusetzen und nachfolgend beim weiteren Ausfahren der Stempelhalterung 4 den Maschinenkörper 2 durch die zwischen Stempelhalterung 4 und Blindmatrize 3` wirkende Stanzkraft des Stempels 5 elastisch aufzuweiten. Genauer gesagt wird dabei der obere Maschinenarm 2b nach oben elastisch ausgelenkt. Wie in 1c, 1d gezeigt, wird an einer ersten Stempelposition z₁, in welcher der Maschinenkörper 2 aufgeweitet ist, eine zugehörige erste Stanzkraft F₁ des Stempels 5 und an einer anderen, zweiten Stempelposition z₂, in welcher der Maschinenkörper 2 weiter als in 1c aufgeweitet ist, eine zugehörige zweite Stanzkraft F₂ des Stempels 5 jeweils mittels des Sensors 11 gemessen.

The procedure for determining the initially unknown punch changing position z _WL of the punch holder 4 is as follows:

• First, the matrix 3 is exchanged for a dummy matrix 3' ( 1b ), which the stamp 5 cannot penetrate in the z-direction. Then the punch holder 4 is extended in the z-direction in order to place the punch 5 on the dummy die 3` and subsequently, as the punch holder 4 is extended further, the machine body 2 is elastically expanded by the punching force of the punch 5 acting between the punch holder 4 and the dummy die 3`. More precisely, the upper machine arm 2b is elastically deflected upwards. As in 1c , 1d shown, at a first stamping position z ₁ , in which the machine body 2 is widened, an associated first stamping force F ₁ of the stamp 5 and at another, second stamping position z ₂ , in which the machine body 2 is wider than in 1c is expanded, an associated second punching force F ₂ of the punch 5 is measured in each case by means of the sensor 11 .

As in 2 shown, a (linear) F(z) expansion characteristic (rigidity characteristic) 12 of the machine body 2 can be calculated from the two (or more) measuring points (z ₁ , F ₁ ) and (z ₂ , F ₂ ) and then the punch position z ₀ can be determined at which the punching force F on the expansion characteristic 12 is equal to zero. this in 1e Stamp position z ₀ shown denotes the force-free stamp placement position in which the stamp 5 touches down on the dummy die 3` when the stamp holder 4 is extended. As in 1b shown, starting from the indirectly determined punch placement position z ₀ , the punch change position z _WL of the punch holder 4 results from the specified change position distance d _WL and the punch length WZL as follows: $${\text{e.g}}_{\text{WL}}={\text{e.g}}_0-\left({\text{i.e}}_{\text{WL}}-\text{WZL}\right).$$

The setting of the punch changing position can thus take place automatically, in particular during operation of the punching machine 1, and with very high accuracy.

Statt erst während der Messung eine Aufweitungskennlinie 12 mithilfe mindestens zweier Messpunkte zu berechnen, kann alternativ die Stempelaufsetzposition z₀ auch anhand einer vorbekannten, ggf. nicht linearen Aufweitungskennlinie 12 des Maschinenkörpers 2 ermittelt werden, indem anhand eines einzigen Messpunkts (z₁, F₁) und der vorbekannten Aufweitungskennlinie 12 die Stempelposition z₀ bestimmt wird, an der die Stanzkraft F auf der vorbekannten Aufweitungskennlinie 12 gleich Null ist.Instead of using a dummy die 3', the initially unknown punch changing position z _WL of the punch holder 4 can also be determined using a workpiece 6 lying on the die 3. From two (or more) measuring points (z ₁ , F ₁ ) and (z ₂ , F ₂ ), the punch position z ₀ can then be determined, in which the punch 5 touches the workpiece 6 when the punch holder 4 is extended. Starting from the indirectly determined punch placement position z ₀ , the punch change position z _WL of the punch holder 4 results from the specified change position distance d _WL , the punch length WZL and the workpiece thickness d as follows: $${\text{e.g}}_{\text{WL}}={\text{e.g}}_0-\left({\text{i.e}}_{\text{WL}}-\text{WZL}\right)+\text{i.e}.$$

Instead of only calculating a widening characteristic 12 during the measurement using at least two measuring points, the punch touchdown position z ₀ can alternatively also be determined using a previously known, possibly non-linear widening characteristic 12 of the machine body 2 by using a single measuring point (z ₁ , F ₁ ) and the known widening characteristic 12 determines the punch position z ₀ at which the punching force F on the known widening characteristic 12 is equal to zero.

Claims (9)

Method for determining a stamp placement position (z ₀ ) of a stamp (5) of a punching machine (1) which has a machine body (2) with a die (3) and in the machine body (2) perpendicular to the die (3) in a z-direction has a movable punch holder (4) with a punch (5) held thereon for punching a workpiece (6) lying against the die (3), with the following method steps: - extending the punch holder (4) in the z-direction in order to move the punch (5 ) on the die designed as a blind die (3`) or on a workpiece (6) without punching it, and then place the machine body (2) through the gap between the punch holder (4) and the blind die (3`) or workpiece (6) expand the acting punching force of the punch (5) elastically; - At a first stamping position (z ₁ ), in which the machine body (2) is expanded, measuring an associated, first stamping force (F ₁ ) of the stamp (5), and - determining the stamping position (z ₀ ) in which the stamp (5) when extending the punch holder (4) on the dummy die (3`) or the workpiece (6), based on the measured first punching force (F <sub>1</sub> ) and an expansion characteristic (12) of the machine body (2). procedure after claim 1 , characterized in that a punch changing position (z <sub>WL</sub> ) of the punch holder (4), in which the punch holder (4) has a predetermined changing position distance (d <sub>WL</sub> ) to the die (3), based on the determined punch placement position (z <sub>0</sub> ), a punch length ( WZL) by which the punch (5) protrudes in the z-direction beyond the punch holder (4) and, if necessary, the workpiece thickness (d) is determined. procedure after claim 2 , characterized in that in the case of a stamp (5) placed on the dummy die (3`), the stamp change position (z _WL ) of the stamp holder (4) is the determined stamp placement position (z ₀ ) minus the difference from the specified change position distance (d _WL ) and corresponds to the punch length (WZL). procedure after claim 2 , characterized in that in the case of a stamp (5) placed on the workpiece (6), the stamp changing position (z _WL ) of the stamp holder (4) is the determined stamp placement position (z ₀ ) minus the difference between the specified changing position distance (d _WL ) and corresponds to the punch length (WZL) plus the workpiece thickness (d). Method according to one of the preceding claims, characterized in that at least one other, second stamping position (z ₂ ) of the stamp (5), in which the machine body (2) is expanded to a different extent than the first stamping position (z ₁ ), an associated , second punching force (F ₂ ) of the punch (5) is measured and the expansion characteristic (12) of the machine body (2) based on the measured first and second punching force (F ₁ , F ₂ ) and the associated punch positions (z ₁ , z ₂ ) is determined. Procedure according to one of Claims 1 until 4 , characterized in that the punch touchdown position (z ₀ ) is determined based on the measured first punching force (F ₁ ), the associated punch position (z ₁ ) and a known widening characteristic (12) of the machine body (2). Method according to one of the preceding claims, characterized in that the punch holder (4) is moved hydraulically in order to provide the respective punching force. Punching machine (1) having an elastically expandable machine body (2) with a die (3), a punch holder (4) which can be moved in a z-direction in the machine body (2) at right angles to the die (3) and has a punch (5) held thereon for Punching of a workpiece (6) lying against the die (3), a sensor (11) for measuring the punching force (F ₁ , F ₂ ) of the ram (5) at at least one ram position (z ₁ , z ₂ ), and a control device (9) which is designed to carry out the method according to one of the preceding claims. punching machine (1) after claim 8 , characterized in that an expansion characteristic (12) of the machine body (2) is stored in the control device (9).

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