EP0143257B1 - Tool holding fixture for a punching press, particularly of a turret cutting press for tool changing - Google Patents

Description

The invention relates to a tool holder according to the preamble of claim 1, starting from DE-A1-331 667.

As is known, the individual tool sets of a turret cutting press are inserted into bores distributed along the circumference of the turret plates arranged one above the other and each consist of at least one punch, one die and one stripper. Depending on the type of attachment of the tools to the turret adjusters, however, a manual conversion process, i.e. the removal of complete tool sets and their replacement by others with numerous handicrafts and thus a great deal of work. There is therefore a need to improve the attachment of the tool to the turret plates with a view to shortening the changeover times. From DE-A1-33 31 667 it is known, for example, to fasten the scraper in a scraper shoe which has a hat which extends radially to the turret plate and is open to the circumference thereof, the side regions of which are profiled in such a way that in connection with lateral Edges of the scraper this is fixed in the vertical direction. In order to prevent the scraper from being inadvertently pulled radially out of this groove, it is secured with a spring-loaded pawl. At the same time, the die of this known turret cutting press is mounted in a die shoe fastened on the lower turret plate, which has a U-shaped recess which is open in the radial direction and into which the die can be inserted. In the inserted state, the die is fixed in the U-shaped recess by means of two spring-loaded clamping levers which engage it laterally. By means of an interchangeable device which releases both the pawl and the clamping lever, both the stripper and the die can be removed from the turret adjusters. However, the tool holder known from this publication is not suitable for the simultaneous replacement of the stamp. In addition, in this known changing device, all devices which serve to solve locking elements for fastening the tools are moved together with the changing device.

A hydraulic press for punching work is known from AT-B-37 00 16, the upper and lower tools of which can be inserted into special holding devices. The upper tool consists of a punch insert, to which a sleeve, which cooperates with a stripper, is movably attached, while the lower tool consists of a die insert with inserted die. The upper and lower tools are fixed in their working position by spring force and can be released hydraulically, the connection between the parts of the upper and lower tools and the above-mentioned inserts being releasable with the aid of hand tools. It is therefore not possible with this known press to directly remove or insert a complete tool set in a simple manner.

It is the object of the invention to design a tool holder of the type described in the introduction in such a way that a complete tool set, consisting at least of punch, stripper and die, can be exchanged in a simple manner. This object is achieved by the features of the characterizing part of claim 1. It is therefore essential that the stamp is also arranged in a receiving device which is open, for example, in the radial direction and which can be configured, for example, as a groove which carries the stamp in the vertical direction . In order to give the punch a defined end position during its insertion into this groove, it is expediently equipped with a stop. All tools of a tool set are fixed in the receiving devices assigned to them by means of special locking elements, which, however, according to the invention can be released by actuating devices located on the machine frame of the turret cutting press. It is therefore advantageous that the functions of a tool changing device to be adapted to this turret cutting press can be limited to the gripping of the tools to be exchanged, since the functions of releasing the locking devices can be carried out by means of special devices already attached to the turret cutting press. A tool changing device can be made much simpler in this way, so that overall the integration of a turret cutting press equipped in this way is simplified in a computer-controlled production.

The features of claim 2 have the advantage that an existing functional element, namely the stamp holder is used as the receiving device for the stamp, which is thus equipped with a groove receiving the stamp. Numerous forms of the groove are available for the form-fitting securing of the stamp with respect to its working direction, which essentially means the vertical direction. By using a known functional element, namely the stamp holder as a receiving device, in particular also reduced constructive adaptation measures when realizing the tool holder according to the invention.

The features of claims 3 and 4 represent a particularly easy to implement locking option of the stamp. Numerous implementation options are conceivable here, the essential functional elements of which consist of the retaining screw, the driving piece and the centering pin, the only requirement being that when screwing in Retaining screw of the centering pin is inserted into the associated bore of the stamp and is pulled out of this bore of the stamp while unscrewing the retaining screw.

The features of claims 5 and 6 give a constructive embodiment again in which way the movements of the retaining screw and the centering pin over the driving piece with the assistance of springs, which here move the driving piece while unscrewing the holding screw from the threaded bore of the stamp influence each other, so that as a result, the blocking effect exerted by the carrier piece on the collar on the centering pin is canceled and the latter is also displaced under the action of the spring assigned to it.

According to claim 7, the head of the retaining screw serves as a coupling element for an actuating device. The actuating device has the purpose here of unscrewing the retaining screw from the associated threaded bore of the punch, so that the head can be equipped, for example, with an internal hexagon or an internal square, into which a correspondingly profiled counterpart of the actuating device can be inserted.

According to claim 8, the die or the die shoe carrying the die is pushed, for example, radially onto the upper side of the lower turret plate, and abuts a securing bolt, through the position of which the die is also given a precisely defined radial position with respect to the turret plate. For precise guidance, the connection between the securing bolt and the die or the die shoe can be designed in such a way that the securing bolt in the end position of the die is in a semicircular recess of the die or the die shoe which is open towards the center of the turret plate, so that an exact fixation is possible. At the same time, a head of this securing bolt, which projects slightly beyond the die or the die shoe, can at the same time provide vertical securing at this point. The two clamping bolts arranged on the side of the die can in principle be of any design, the only thing that is important is that their form-fitting connection to the die or the die shoe can be released by as simple a movement as possible. In this way, the die is reliably locked at three points, with a corresponding design of the tensioning bolts, which should at the same time have a securing function in the vertical direction.

The features of claim 9 have the advantage that to solve the locking function of the clamping bolt, they only have to be rotated through an angle of approximately 180 °. In this way, the construction of a corresponding actuating device, with which this releasing movement is mechanized, is simplified.

The component taking over a coupling function between the clamping bolts and an actuating device according to claim 10 can in principle be of any shape. Here too, for example, the arrangement of an internal hexagon or square is appropriate, which is brought into engagement with a corresponding counterpart of the actuating device.

With the features of claim 14, the design effort in handling the individual tools of a tool set can be kept low. In this case, the bores equipped without a pin only take on a vertical support function, while the bores equipped with a pin take on both such a support function and a securing function. A tool changing device to be adapted to these tools could thus be characterized, for example, by a total of three pairs of bolts which can be individually displaced in the direction of the tools, the bolts which are inserted into the bores equipped with the pins having to have a corresponding profile so that a positive fit via the pins mentioned Fixation of the tools can take place.

• Fig. 1 einen Vertikalschnitt durch die Revolverteller einer erfindungsgemäßen Revolverschneidpresse;
• Fig. 2 eine Ansicht einer erfindungsgemäßen Revolverschneidpresse gemäß Pfeil II der Fig. 1;
• Fig. 3 bis 5 diverse Querschnittsformen der in den Stempelhalter eingearbeiteten Nuten;
• Fig. 6 eine Ansicht des Stempels in einer Ebene gemäß Pfeil VI-VI der Fig. 1;
• Fig. 7 eine Ansicht des Abstreiferschuhs in einer Ebene VII-VII der Fig. 1;
• Fig. 8 eine Ansicht des Matrizenschuhs in einer Ebene VIII-VIII der Fig. 1;
• Fig. 9 eine schematische Darstellung der dem Stempel zugeordneten Betätigungseinrichtung;
• Fig. 10 eine Draufsicht gemäß Pfeil X der Fig. 9;
• Fig. 11 eine schematische Darstellung einer der Matrize zugeordneten Betätigungseinrichtung;
• Fig. 12 eine Seitenansicht der Darstellung der Fig. 11;
• Fig. 13 eine Ansicht in einer Ebene XIII-XIII der Fig. 11.

Further advantages of the invention result from the following embodiment shown in the drawings. Show it:

• 1 shows a vertical section through the turret plate of a turret cutting press according to the invention;
• FIG. 2 is a view of a turret cutting press according to the arrow II of FIG. 1;
• 3 to 5 various cross-sectional shapes of the grooves machined into the punch holder;
• Fig. 6 is a view of the stamp in a plane according to arrow VI-VI of Fig. 1;
• Fig. 7 is a view of the scraper shoe in a plane VII-VII of Fig. 1;
• Fig. 8 is a view of the matrix shoe in a plane VIII-VIII of Fig. 1;
• 9 shows a schematic illustration of the actuating device assigned to the stamp;
• Fig. 10 is a plan view according to arrow X of Fig. 9;
• Fig. 11 is a schematic representation of one of the Actuator associated with die;
• Fig. 12 is a side view of the illustration of Fig. 11;
• FIG. 13 is a view in a plane XIII-XIII of FIG. 11.

1 and 2 in FIG. 1 each designate the upper and lower turret plates of a turret cutting press, not shown, which are rotatably mounted about a vertical axis. The revolver plates 1 and 2 each have locking bushes 3, 4 on the circumference, by means of which the revolver plates can be determined in certain rotational angle positions, for example the punching position. This locking is carried out by means of, for example, pneumatically operated locking bolts, not shown here, which are inserted into these locking bushes.

The upper turret plate 1 is provided with a series of holes 5 arranged on the circumference, in each of which a punch holder 6 is inserted in a sliding manner. A barrel spring 8, which is guided in a groove 9 in the bore 5, ensures a torsion-free fit of the punch holder 6.

The stamp holder 6 ends in its upper region in a head plate 7, which is equipped with a central bore 14 extending in the longitudinal direction of the stamp holder. A coupling pin 13 protrudes from the plane of the head plate 7, through which the bore 14 is passed. In the rest position shown in FIG. 1, the stamp holder 6 is secured vertically by a stamp holder plate 35 in the position shown in that the coupling pin rests on the edge of the stamp holder plate.

In the working position, the coupling pin 13 is coupled with a machine tappet, not shown here, which moves the punch holder 6 in the vertical direction to carry out punching work.

At the end of the punch holder 6 facing away from the coupling pin 13, the punch 22 is screwed essentially by a centrally arranged retaining screw 12. The head 37 of the retaining screw 12, which is equipped with a hexagon socket, is supported via a driving piece 50 on an annular pressure surface 51, the retaining screw further extending in a bore 11 which merges at a point 52 into a bore 53 of smaller diameter, to which in turn a threaded bore 24 connects which runs in the punch 22. A spring 15 is supported on the annular surface of the stamp holder 6 thus resulting at the point 52, the end of which, opposite the point 52, presses against the lower side of the driving piece 50. The spring 15 is under tension in the installation position shown here.

To the side of the retaining screw 12 is a centering pin 16, which in the installed state extends through a hole 54 in the punch holder 6 into one

Bore 25 extends into it, which is located in the stamp 22. The bore 54 merges into a bore 20 of larger diameter at the point 55. The centering pin 16 has at its upper end two bundles arranged at a distance from one another, which are each arranged below and above the driving piece 50. In the installation position shown in FIG. 1, the lower collar 18 is pressed against a lower side of the driving piece 50 by a spring 17 which is supported on the one hand on an annular surface located at point 55 and on the other hand with respect to this collar 18. The upper collar 19 is in this installed position at a distance above the associated upper side of the driving piece 50.

Both the head 37 of the retaining screw 12 and the centering pin 16 with its upper collar 19 protrude into a recess 10 in the punch holder 6, which is essentially covered by the head plate 7. The head plate 7 is fastened to the stamp holder 6 by means of screws 56.

The positive locking of the stamp 22 on the stamp holder 6 will be described in more detail.

On the underside of the turret plate 1, a scraper shoe 27 is held by scraper bolts 28, the scraper bolts being guided through holes 57 in the upper turret plate 1, which pass into holes 59 of larger diameter at point 58. The upper end of the scraper bolt 28 is formed by a collar 30, the scraper bolt being held in the rest position shown by a spring element 60 which is supported on the one hand on the annular surface resulting at point 58 and on the other hand on the underside of the collar 30. The scraper bolts 28 are slidably guided in the bores 57 and can be actuated by plungers (not shown in FIG. 1) in order to move the scraper shoe 27 to carry out punching work.

The scraper shoe 27 has a substantially U-shaped recess which is open in the direction of the arrow 61 and into which the scraper 31 is inserted and is here positively secured essentially by a circumferential groove 32 into which a flange 33 of the scraper projects. Further securing of the position of the scraper 31 will be discussed in the following. It is essential that both the punch 22 and the scraper 31 can be removed from the turret plate 1 in the direction of the arrow 61 or in the opposite direction, respectively, or can be inserted therein.

The lower turret plate 2 carries a mounting plate 38 which is fastened thereon by screws, not shown here, for example. The mounting plate 38 is equipped with a central bore 62 serving for the stamping process, which is aligned with a bore 63 in the lower turret plate 2 and carries on its one the outer peripheral surface of the turret 2 opposite end a locking pin 64 which is screwed into the mounting plate 38. The securing bolt 64 is used for radial support of a die shoe 39 with respect to the turret plate 2, which is provided at this point with a flattened portion 65, which is characterized by a U-shaped recess which is open in the direction of the arrow 66 and which engages under a collar of the securing bolt 64 . Further securing or fastening elements of the die shoe 39 will be discussed in the following. The die shoe 39 carries a die 21.

In FIG. 2 and the other graphical representations, functional elements that correspond to those of FIG. 1 are designated with the same reference numerals, so that a repeated description is unnecessary.

FIG. 2 shows a view of the tool set of a turret cutting press from the direction in which this tool set, which consists of the punch 22, the stripper 31 and the die shoe 39 with the die 21 held therein, is replaced. It can be seen that the stamp 22 is equipped on both sides in this viewing direction with a flange 23 which is held in a corresponding groove of the stamp holder 6 which runs perpendicular to the plane of the drawing in FIG. 2, so that the stamp 22 is positively locked in the vertical direction in this way is secured. The stamp 22 finds a radial stop within the stamp holder 6 in a pin 34 (FIG. 1) which is inserted into a bore 92 extending parallel to the retaining screw 12.

One can also see the flange 33 running on both sides of the scraper, which is also supported in corresponding grooves in the scraper shoe 27 in such a way that the scraper 31 can be pulled out perpendicular to the plane of the drawing in FIG. 2. Protection against inadvertent pulling out of the scraper 31 is achieved by a spring-loaded pawl 93 known per se.

The die shoe 39 is secured against unintentional removal perpendicular to the plane of the drawing in FIG. 2 by means of clamping bolts 26 which are arranged on both sides. The detailed design and operation of these clamping bolts 26 will be explained.

The punch 22, the stripper 31 and the die shoe 39 are each equipped with two bores 40, 41 arranged next to one another, which essentially extend horizontally. The bores 40, which are essentially arranged one below the other, have in common that they are partially penetrated in their respective right-hand edge region by a further bore 36 of smaller diameter, in each case pins 94 being inserted into these bores 36, as shown in the projection in FIG. 2 thus partially protrude into the bores 40. The meaning of these pins 94 in the context of the embodiment will also be explained in the following.

3, 4 and 5 show different configurations of the lower region of the stamp holder 6, which serve to guide the stamp 22. While only a rectangular groove 47 is present in FIG. 3, which therefore does not permit vertical fixation of the stamp, FIG. 4 shows a dovetail-shaped groove 48 or a rectangular groove 49 provided with an underhand grip. The embodiments according to FIGS. 4 and 5 confer the stamp 22 thus a vertical fixation. In Fig. 1, a rectangular groove with a grip is shown schematically at 49.

6, 7 and 8 serve to explain the mode of operation of the bores 40, 41. While the bores 41 serve to receive a removal pin 46 which is not rotatably mounted on a tool changing device (not shown here), a removal pin 43 which is rotatably mounted on this tool changing device about its longitudinal axis can be inserted. This removal pin 43 is characterized in its area introduced into the bore 40 by a flattened portion 69, which gives it a circular segment-shaped shape in cross section. In the round part of this cross section, a locking groove 70 is worked in, the radius of which — seen in cross section — corresponds to the radius of the pins 94. During the insertion of the removal pins 43 into the bores 40, these are in an angle of rotation position in which the flat 69 is on the side facing the pins 94. It can be seen that in this rotational angle position an easy insertion of the removal pins 43 into the bores 40 is possible. Then the removal pins 43 are rotated by 180 °, so that the locking groove 70 with the pins 94 are positively engaged. In this way, the punch 22, the scraper 31 and the die shoe 39 are positively attached to the tool changing device, not shown here, and can be removed from the mounts assigned to them in this way. It is essential for these brackets that, as can be seen, for example, from FIGS. 7 and 8, they are U-shaped, i.e. are open in the direction of arrow 61, so that removal of the punch 22, the stripper 30 and the die shoe 39 in this direction or insertion in the opposite direction to the arrow 61 is possible in a purely mechanical way.

9 and 10 show the mechanism by means of which the attachment of the stamp 22 and the scraper 31 to the upper turret plate 1 can be released by machine. For this purpose, the turret cutting press is on the machine frame 42 a vertically movable carriage 44 is attached, which can be moved by means of a piston-cylinder unit 45 which can be loaded on both sides. For this purpose, the cylinder of the piston-cylinder unit 45 is fastened to the machine frame 42 via a mounting plate 71, while its piston rod 72 is connected to the slide 44. A mechanical screwdriver 73 is fastened on the slide 44, and the screw spindle 74 provided with an external hexagon can be inserted through the bore 14 of the coupling pin and into the head 37 of the retaining screw 12.

As can be seen in detail from FIG. 10, the slide 44 is mounted on the machine frame 42 so as to be pivotable about a vertical axis 74 ', so that the complete punch holder 6 can occasionally be removed from the turret plate 1 for maintenance purposes. In the working position shown in the drawings, the carriage 44 is secured by a pawl 75, which is only indicated schematically.

The structural design and the mode of operation of the clamping bolts 26 are explained below with reference to FIGS. 8 and 11:

The clamping bolt 26 is provided below its head with a recess 76 which is designed as a flattening of the shaft of the clamping bolt which is otherwise circular in cross section. The die shoe 39 also has flattened areas 77, which are provided with semicircular recesses 78, the radius of these semicircular recesses 78 essentially corresponding to the radius of the shaft of the clamping bolts 26 in this area. If the clamping bolt 26 is thus in a rotational angle position with respect to its longitudinal axis, in which the round section of the cross section engages in the respective semicircular recess 78, the die shoe 39 is positively secured with respect to a movement perpendicular to the plane of the drawing in FIG. 11. The depth of the recess 76 radially to the shaft of the clamping bolt 26 is such that after rotation of the clamping bolt 26 by 180 ° with respect to the position shown in FIG. 11, the recess 76 now faces the respective recess 78, in which position the die shoe 39 is no longer locked by the clamping bolt 26.

11, 12 and 13 also show a mechanism by means of which the positive locking caused by the clamping bolts 26 can be released mechanically.

For this purpose, a boom 79 is attached to the machine frame 42 below the lower turret plate 2 and carries a piston-cylinder unit 81, which can preferably be acted upon on both sides, on an angle bracket 80. A mounting plate 83 is fastened to the piston rod 82 of this piston-cylinder unit 81 and can be moved along two stationary, vertically arranged guide bolts 84. The mounting plate 83 carries two rotary assemblies 85 at a distance from one another and in a position which enables the coupling pins 86 connected to the output shafts of these rotary assemblies 85 to be inserted into depressions 87 in a component 88 which is connected in a rotationally rigid manner to the clamping bolt 26.

The mode of operation of the described tool holder, which will be easy to understand from the preceding illustrations, is briefly explained below:

It is assumed that at the same time a complete tool set consisting of a punch 22, a scraper 31 and a die shoe 39 with a die 21 arranged therein is to be replaced.

After the turret plates have been fixed in a certain position for tool change by means of the locking bushings 3, 4, the slide 44 is moved vertically in the direction of arrow 89 (FIG. 9) by acting on the piston-cylinder unit 45, so that the screw spindle 74 , in particular whose end region provided with an external hexagon is brought into engagement with the internal hexagon of the head 37 of the retaining screw 12 through the bore 14 of the coupling pin 13. At the same time, the mounting plate 83 is moved upward in the direction of arrow 90 (FIG. 12) by pressurizing the piston-cylinder unit 81, so that the coupling pins 86 are coupled to the recesses 87.

By actuating the screwdriver 73, the retaining screw 12 is released, which, after it has been completely screwed out of the threaded bore 24, is raised by the relaxing spring 15, which presses on the underside of the driving piece 50. This lifting is achieved in that the driving piece 50 acts on the form-fitting head 37 held in this.

The lifting of the driving piece 50 has the result that the centering pin 16 can also be raised under the action of the relaxing spring 17 after the lower collar 18 no longer abuts the underside of the driving piece 50. In this way, the centering pin is completely pulled out of the bore 25 of the punch 22, so that the locking of the punch caused thereby is released.

By means of the rotating assemblies 85, the clamping bolts 26 are now rotated by 180 °, so that the recesses 76 of the clamping bolts 26 are now on the side facing the recesses 78 of the die shoe 39 and the locking achieved by the clamping bolts 26 is also released.

At this point it should be mentioned that before the stripper 31 is pulled out Locking must be released by the pawl 93, which can be carried out with a tool changing device, which will not be described here in a simple manner at the same time during the actuation of the rotating assemblies 85 and the screwdriver 73.

Then removal pins 43, 46 of a tool changing device are inserted into the holes 40, 41 assigned to them, the removal pins 43 being in such an insertion phase in such an angular position that their flats 69 are on the side facing the pins 94. Subsequent rotation of the removal pins 43 through 180 ° achieves a fixation of the plunger 22, the stripper 31 and the die shoe 39 with respect to the tool changing device, which acts in the horizontal plane, so that a subsequent removal of this tool set from the turret plates 1, 2 is possible without that some manual intervention is required.

A tool set is inserted in the opposite way, i.e. by means of the removal pins 43, 46, on which the tool set is located, it is inserted into the corresponding receptacles of the turret plates 1, 2, namely the punch 22 into the rectangular groove 49, the stripper 31 into the groove 32, while the die shoe 39 is on the mounting plate 38 is shifted until its semicircular recess in the area of the flat 65 engages under the head of the securing bolt 64 and the wiper shoe is locked in this way in this way. During the introduction of the scraper 31, the pawl 93 must be released, which must also be carried out simultaneously with its insertion.

The retaining screw 12 of the punch holder 6 is in the unscrewed position during this insertion phase of the tool set, so that the centering pin 16 is also withdrawn, i.e. is located completely within the bore 54 of the punch holder 6. Subsequently, the holding screw 12 is screwed into the threaded bore 24 of the plunger 22 by actuating the screwdriver 73, as a result of which the driving piece 50 is pressed downward and the spring 15 is compressed. This displacement of the driving piece 50 also has a

Compression of the spring 17 and a corresponding displacement of the centering pin 16 so that the latter penetrates into the bore 25 of the plunger 22 and locks it in this way. After the pawl 93 has also assumed its locking function and by means of the coupling pins 86 and the rotating assemblies 85, the clamping bolts 26 have been rotated by 180 °, so that their recesses 76 are now on the side facing away from the semicircular recesses 78 of the die shoe 39, this is Tool set completely locked in the corresponding holders of the turret plates 1, 2.

The locking grooves 70 are then rotated out of the area of the pins 94 by rotating the removal pins 43 through 180 °, so that the removal pins 46, 43 can then be withdrawn.

The turret cutting press described is thus characterized by a tool holding system, which enables a complete removal of a complete tool set in the radial direction to the turret adjusters 1, 2, whereby the prerequisites for interaction with a computer-controlled tool changing device have been created.

A in FIGS. 6 to 8 denotes the identical distances between the bores 36 (FIG. 2) and the pins 94 from the outer boundary surfaces 95 of the stamp 22, the stripper 31 and the die shoe 39.

Claims (14)

1. Tool holder of a piercing press, particularly a turret piercing press, whose turret plates (1, 2) are set up to receive a plurality of tool sets consisting of at least a ram (22), a stripper (31) and a matrix die (21), wherein the stripper (31) and the matrix die (21) are arranged, with the aid of locking elements, in receiving devices which are shaped to be open horizontally and in the radial direction with reference to the turret plates (1,2),
characterised in that each tool of a tool set is arranged in any one receiving device of the respective turret plate (1, 2) which is open in the horizontal, preferably radial direction, so that an insertion and a removal of all tools of a tool set is possible in the horizontal, preferably radial direction by means of one tool changing device, in that the ram (22), the stripper (31) and the matrix die (21) are form-lockingly held with the aid of locking elements in the respective receiving device, and in that on the machine frame of the piercing press are arranged individual actuating devices for releasing and for arresting the locking elements, said actuating devices being switchable independently of the tool changing device.

2. Tool holder of a piercing press according to claim 1, characterised in that the receiving device cooperating with the ram (22) is a ram holder (6) whose lower region, i.e. the region adjacent to the ram (22), is provided with a groove (48,49), the ram (22) being form-lockingly secured with reference to its working direction by the cross sectional shape of said groove.

3. Tool holder of a piercing press according to claim 1 or 2, characterised in that the locking element cooperating with the ram (22) comprises at least one centering pin (16) which can be brought into engagement with a bore (25) of the ram (22) and which also is guided within the receiving device of the ram (22), for example in a bore (54) of the ram holder (6).

4. Tool holder of a piercing press according to claim 3, characterised in that the centering pin (16) is insertable into the bore (25) for locking the ram (22) by way of an entraining member (50) by means of a retaining screw (12) arranged spaced from the centering pin, said entraining member being slidingly guided within the ram holder (6), and said retaining screw being insertable into a threaded bore (24) of the ram (22).

5. Tool holder of a piercing press according to claim 4, characterised in that between the entraining member (50) and the ram holder (6) there is arranged a spring (15) which is compressed by screwing in the retaining screw (12) into the threaded bore (24) and which, upon release of the retaining screw (12), displaces the entraining member (50) relative to the ram holder (6).

6. Tool holder of a piercing press according to one of claims 4 or 5, characterised in that between the ram holder (6) and a collar (18) formed on the centering pin (16) there is arranged a spring (17), and in that the collar (18) abuts against one side of the entraining member (50) in such a way that with the retaining screw (12) screwed in by means of the entraining member (50) and the collar (18) the centering pin (16) is guided into the bore (25) with compression of the spring (17).

7. Tool holder of a piercing press according to one of claims 4 to 6, characterised in that the retaining spring (12) is provided with a head (37) which forms a coupling element for an actuating device.

8. Tool holder of a piercing press according to one of the preceding claims, characterised in that the locking elements cooperating with the matrix die (21) comprise a safety pin (64) and two clamping pins (26), wherein the clamping pins (26) are arranged on both sides of the direction of insertion and of removal of the matrix die (21), wherein the clamping pins (26) are movable for the making of a form-locking connection with the matrix die (21), preferably are mounted to be rotatable about their longitudinal axes, wherein this form-locking connection is so formed that the matrix die (21) is fixed both with reference to the direction of removal and of insertion of the matrix die and also in a direction perpendicular to this direction, and wherein the safety pin (64) essentially constitutes an abutment point.

9. Tool holder of a piercing press according to claim 8, characterised in that the clamping pins (26) include a recess (76) at their upper end regions beneath their respective heads, i.e. at the end regions adjacent to the matrix die (21), so that the cross section of the clamping pins (26) in the region of these recesses has a shape which is a segment of a circle, wherein the rounded section of this shape, in the arresting position of the clamping pins (26), is in engagement with approximately semi-circular recesses (78) of the same radius in the matrix die (21) or in a matrix shoe (39) carrying the matrix die (21), and wherein in the open position of the clamping pins (26) their rounded sections are located on the side remote from the recesses (78) so that there is no engagement between the clamping pins (26) and the said recesses (78).

10. Tool holder of a piercing press according to claim 8 or 9, characterised in that the clamping pins (26) are connected at their ends remote from the matrix die (21) with a component (88) which constitutes a coupling element for an actuating device.

11. Tool holder of a piercing press according to one of the preceding claims, characterised in that the locking element cooperating with the stripper (31) is a latching mechanism (93) which is preferably spring-loaded and which is known per se.

12. Tool holder of a piercing press according to one of the preceding claims 7 to 11, characterised in that the actuating device cooperating with the head (37) of the retaining screw (12) formed as a coupling element is a motor-driven rotary drive means arranged to be displaceable in direction towards the head (37), the rotary drive means being arranged to be coupled to the head (37) and preferably comprising a screwing tool (73).

13. Tool holder of a piercing press according to one of the preceding claims 10 or 11, characterised in that each component (88) of the clamping pins (26) arranged on the two sides of a matrix die (21) can be coupled to a rotary drive means arranged to be motor-driven and displaceable in direction towards the said components (88).

14. Tool holder of a piercing press according to one of the preceding claims, characterised in that the ram (22), the stripper (31) and the matrix die (21) or the matrix shoe (39) are provided with two pairs of bores (40, 41 ) arranged spaced from one another and extending in the direction of removal and of insertion of these tools, in that the bores (40) are intersected in their edge regions by perpendicularly extending bores (36) in each of which a pin (94) is inserted, so that the pin (94) projects partially into the bore (40), and in that the bores (36) are located at a defined distance (A) from the outer limit surface (95) of the respective tool.

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