ES2963928T3 - Deep drawing tool for deep drawing of blanks - Google Patents

Abstract

The invention relates to a deep drawing tool (100) for drawing blanks (106) from sheet material to form molded blanks, comprising a drawing core (102) and a drawing bell (104). , which can move linearly relative to each other. and a blank holder (110) as a stop for at least a portion of the lower edge region of the drawing bell (104), wherein the drawing bell (104) has a radially outer portion (124) and at minus one radially inner part (126), which is movable with respect to the outer part (124). The invention further relates to a corresponding method. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Deep drawing tool for deep drawing of blanks

The present invention relates to a deep drawing tool for deep drawing blanks from sheet metal material to form blanks, according to the preamble of claim 1, and to a corresponding method.

US 5,187,966 A discloses a method and a corresponding device for deep drawing containers, a drawing bell being lowered onto a drawing core. Comparable devices are shown in US 3,372,569 A, IT 1225740 B and JP 2005028427 A.

Such deep drawing tools are used in particular for the production of metal containers such as, for example, container lids or cans. The blanks are punched from sheet metal panels and deep drawn into a deep drawing tool so that they obtain an approximately pot shape. The deep drawing tool comprises a drawing core and a drawing bell, which can be moved linearly relative to each other, such that the drawing bell and the drawing core can move towards each other and be inserted into each other. in the other one. This movement is hereinafter called "deep drawing movement". In a known and customary arrangement, in this case the drawing bell approaches the drawing core from a running position remote from it and is guided over the drawing core. In this case it may be a downward movement of the drawing bell, but a reverse arrangement is also conceivable, in which the drawing bell approaches the drawing core from below. Furthermore, the drawing core may be arranged stationary, but this does not necessarily have to be the case; instead, the drawing core can be moved towards a stationary drawing bell. In this regard, different variants of a relative movement between the drawing bell and the drawing core are therefore possible to carry out the deep drawing process.

A so-called holder serves as a counter support for at least a part of the lower edge area of the drawing bell. It may, for example, be arranged in the form of a ring around the drawing core and be elastically mounted so that it exerts a counterforce in the direction of the drawing bell during the deep drawing movement. In this way, the edge area of the blank is wedged between the drawing bell and the holder. This prevents folds from forming on the edge of the blank due to compression of the material. However, on the other hand, the interlocking entails the problem that, in the blank formed part, when leaving the interlocking, so-called material lobes and/or, in the case of lacquered material, so-called lacquer filaments can form. , that is, formations similar to hairs and particles of material that can contaminate the tool and subsequent machines.

There are different solution approaches to reduce the formation of such lacquer filaments, lobes and material particles. For example, EP 2 125264 B1 shows a deep drawing tool in which the holder is pressed by a pneumatic spring, the so-called drawing cushion, in the direction of the drawing bell. Overriding the locking by the deepening holder is achieved by a sudden deflation of the deepening cushion, so that the counterforce is set to zero.

However, the use of a pneumatic stuffing cushion of this type is associated with various disadvantages, which are avoided by the solution shown in document DE 102015 113267 A1 of the applicant. Instead of a pneumatic drawing cushion, force transmission means are actuated during the deep drawing movement, which apply a spring force to the holder, to produce a movement ahead of the drawing bell. By this forward movement, the holder is removed from the drawing bell and the locking effect of the holder is cancelled. This releases the edge of the blank, thereby preventing the formation of material lobes and lacquer filaments.

These solutions known from the state of the art have in common that the support counterforce exerted by the fastener in the direction of the drawing bell must be completely overcome to cancel the locking. Furthermore, in cases where blank shaped parts with or without residual flange are drawn very deeply, the problem arises of reducing the necessary, initially high, supporting counterforce selectively and dosing it in such a way. that, on the one hand, an interlock is still exerted on the residual lip that prevents the formation of folds, but, on the other hand, it is kept so low that the material of the blank does not narrow or tear due to stretching. . This requires a control of the support counterforce that cannot be carried out with the state of the art described above.

Therefore, it is an object of the present invention to improve a deep drawing tool of the generic type in such a way that the supporting counterforce acting against the drawing bell or the residual lip of the blank during the drawing movement depth can be controlled and dosed more specifically and efficiently than in the case of the state of the art.

According to the invention, this objective is solved by a deep drawing tool with the characteristics of claim 1.

According to the invention, the drawing bell of the deep drawing tool has a radially outer part and at least one radially inner part. In this way, the drawing bell is divided. The radially inner part is movable with respect to the outer part. Therefore, in a position of the drawing bell in which the supporting counterforce of the fastener acts as a locking force against the radially outer part of the drawing bell, the radially inner part can bypass this supporting counterforce and move away from the fastener. in relative movement with respect to the radially outer part. This can be achieved by releasing a coupling between the radially outer part and the radially inner part after both parts have initially moved together in sections and after this coupling has been released, the inner part is free to move with respect to the outer part. However, a guided movement of the inner part is also conceivable, so that it can be moved in a controlled manner, for example by means of a drive provided for this purpose, to carry out the relative movement.

Therefore, the support counterforce is reduced only in one part of the drawing bell, namely the radially inner part. Therefore, no or only very little energy input is needed to reduce the support counterforce. In any case, this energy input can be kept lower than in the state of the art.

To avoid the problems that occur in the state of the art, it is sufficient to reduce the interlocking of the residual edge of the blank only in the radially inner area of the drawing bell during the deep drawing movement. This reduction may occur at a point in the deep drawing motion where the blank has been stretched so much that only a relatively narrow residual lip remains between the inside of the drawing bell and the holder. In this way, the desired goal of avoiding lacquer filaments can be achieved with relatively little effort. Alternatively, very deep drawing of blanks with or without residual flange is possible by metering the latch again on the inner edge of the drawing bell.

According to the invention, the deep drawing tool has drive means for the deep drawing movement, in which the drawing bell and the drawing core move towards each other and are inserted into each other. .

Preferably, the deep drawing tool according to the invention comprises coupling means through which the outer part and the inner part of the drawing bell are coupled during the deep drawing movement and which are provided to cancel this coupling. when a predetermined point of the deep drawing movement is reached. In this case, the coupling means may therefore be provided to couple the inner part and the outer part of the drawing bell during a section of the movement path of the deep drawing movement, in such a way that they realize a identical or synchronized movement. After canceling this coupling, the outer part and the inner part can move with respect to each other in such a way that the previously described cancellation of the locking in the inner part of the drawing bell becomes possible, or the inner part It is freely movable and without drive, while the relative movement between the outside of the drawing bell and the drawing core continues.

Furthermore, preferably, the coupling means comprise means for positively fitting the outer part and the inner part into each other of the drawing bell. These means may comprise, for example, driving elements or stops that are provided on the outside and inside of the drawing bell and that engage or abut each other during the deep drawing movement, canceling this engagement or stop when the predetermined point of the deep drawing movement is reached, so that decoupling is achieved.

According to the invention, the coupling means comprise means for exerting a retaining force on the interior part of the drawing bell to retain it in a fixed position with respect to the exterior part.

According to a particular embodiment of the present invention, these means for exerting a retaining force comprise at least one spring by which the inner part of the drawing bell is pressed into a fixed position with respect to the outer part. This fixed position can, for example, be defined by a stop on the outside, against which the inside is pressed by the spring.

Preferably, this spring is a mechanical spring.

According to an alternative embodiment, this spring is a pneumatic spring.

According to the invention, the deep drawing tool comprises means for canceling or reducing the retention force in the interior part of the drawing bell. This allows the locking force between the fastener and the drawing bell to be completely neutralized or re-dosed on the inside.

Preferably, in this case, the spring is a compression spring that is pretensioned between the inner part of the drawing bell and a counter support, and the means for canceling or reducing the retention force comprise a drive for moving the counter support in a direction to relax the compression spring. This reduces the pressure exerted by the compression spring on the inside of the drawing bell. The compression spring can be, for example, a mechanical compression spring, wherein the counter support can be formed by a spring support. It is also possible that the compression spring does not act directly on the inside of the drawing bell, but rather through coupling elements, so that the pressure of the compression spring is transmitted through such elements. In particular, however, the compression spring may also be a pneumatic compression spring, and the counter support is formed by a piston which is moved by the drive in such a way that the pneumatic compression spring is relaxed. The piston can, for example, delimit a pressure chamber, the volume of which is increased by the movement of the piston.

According to another embodiment of the invention, the spring is a compression spring that is prestressed between the outside of the drawing bell and a counter support, through which the spring pressure can be transmitted to the inside of the drawing bell. stuffing bell. Also in this case, the compression spring can optionally be a mechanical spring or a pneumatic spring. In the latter case, the counter support can in turn be formed by a pneumatic spring piston, which acts directly or indirectly on the interior part of the drawing bell.

Preferably, in this case the means for canceling or reducing the retention force comprise a drive for moving the counter support in the direction of tension of the compression spring. In the case of a mechanical spring, the drive can move, for example, a spring support that forms the counter support and to which one end of a mechanical spring is attached. In the case of a pneumatic spring, the drive can move, for example, a piston forming the counter support in one direction to reduce the volume of a pressure chamber forming a pneumatic spring cushion, so that the tension of the air spring is increased. pneumatic compression spring.

According to a further preferred embodiment, the means for canceling or reducing the retention force comprise a stop that is arranged to be received by the counter support during the deep drawing movement and upon contact of which the counter support is pressed in a direction in the that the compression spring is tensioned when it is pre-tensioned between the outside of the drawing bell and the counter support or it is relaxed when it is pre-tensioned between the inside of the drawing bell and the counter support. This stop can be arranged, for example, radially in the peripheral area of the outer part of the drawing bell, so that a driving element fixed to the counter support receives the stop during a movement of the drawing bell. However, other arrangements of this stop are also possible, for example in the radially inner area of the outer part of the drawing bell.

Furthermore, preferably, the spring comprises a pneumatic spring cushion with a first pressure chamber and means for transmitting the pneumatic pressure in the first pressure chamber to the interior part of the drawing bell, comprising means for canceling or reducing the pressure. retaining force means for controlling the pneumatic pressure in the first pressure chamber.

Preferably, in this case the means for controlling the pneumatic pressure in the first pressure chamber comprise a ventilation device. By venting the first pressure chamber, the spring pressure on the inside of the drawing bell decreases.

Furthermore, preferably, the means for controlling the pneumatic pressure in the first pressure chamber comprise a piston that delimits the first pressure chamber and is arranged movably to modify the volume of the first pressure chamber. If the piston moves to increase the volume of the first pressure chamber, the pneumatic pressure is reduced.

According to a further preferred embodiment, the deep drawing tool according to the invention comprises a second pressure chamber which is separated from the first pressure chamber by the piston.

According to a further preferred embodiment of the present invention, the coupling means comprise a driving element for the inner part of the drawing bell, which is held on the outside of the drawing bell by magnetic force in a magnetic support with switchable polarity, such that in a first switching position it occupies a first axial position and in a second switching position it occupies a second axial position that is linearly displaced with respect to the first axial position.

According to another preferred embodiment, the coupling means comprise a driving element for the interior part of the drawing bell, which is arranged in a radially movable manner on the outside of the drawing bell and is held until the predetermined point is reached. of the deep drawing movement by means of a cam track that is arranged stationary with respect to the drawing bell or that moves together with the drawing core in a position of engagement with the inner part of the drawing bell and when reaches this predetermined point it is released for a radial displacement, by which the inner part of the drawing bell is released from the socket.

Furthermore, preferably, the drawing bell comprises a first radially internal part and a second radially internal part, the first internal part being arranged between the external part and the second internal part, the deep drawing tool comprising other coupling means by which the first inner part and the second inner part are coupled during the deep drawing movement and are provided to cancel this coupling when another predetermined point of the deep drawing movement is reached. This allows, for example, to move the two radially inner parts and also the outer part coupled to each other during the deep drawing movement, to initially cancel the coupling with the outer part at a certain point of the deep drawing movement so that only the two inner radial parts remain coupled and, finally, also uncouple the coupling of the two inner radial parts in a later state. This creates another possibility for graduated control of the locking force in different radial parts of the drawing bell. In the context of the present invention, it is not ruled out that other parts of the drawing bell are also present, that is, a third radially inner part, etc., which are movable with respect to the other parts or can be coupled to them to its movement.

Preferably, in this case, the other coupling means are provided to uncouple the coupling of the first inner part and the second inner part after reaching the predetermined point of the deep drawing movement, in which the outer part and the inner part of the stuffing bell is disengaged.

The present invention further relates to a method for deep drawing blanks of sheet metal material to form blanks using a deep drawing tool of the type according to the invention, as described above, comprising the following stages:

a) make the drawing bell and the drawing core available in a running position in which a free space remains between the lower side of the drawing bell and the drawing core, leaving the lower sides of the radially outer part and the radially inner part of the drawing bell essentially flush with each other;

b) positioning a blank in the free space;

c) carrying out a deep drawing movement by which the drawing bell and the drawing core move towards each other in such a way that the edge of the blank projecting radially above the drawing core is interlocked between the underside of the drawing bell and the fastener and is drawn above the drawing core;

d) continue the deep drawing movement until the outer edge of the deep drawn edge of the blank is wedged between the underside of the radially inner part of the drawing bell and the holder;

e) annulling the coupling between the radially outer part and the radially inner part of the drawing bell, the radially inner part being freely movable with respect to the radially outer part or being actuated to move in this way with respect to the outer part ;

f) further continue the deep drawing movement with contact between the holder and the outside of the drawing bell.

Here it is possible that in step e) or in the subsequent step f) the cancellation of the coupling between the radially external part and the radially internal part of the drawing bell is checked again, that is, that a new coupling takes place. the two parts of the deep-drawing bell with each other.

Furthermore, preferably, in step f) the drawing core is further introduced into the radially inner part of the drawing bell, so that the blank continues to be deeply drawn and the residual rim is further reduced in size or the Deep drawn edge of the blank is fully stretched.

Below, preferred embodiments of the present invention are explained in more detail with the aid of the drawing.

Figures 1a and 1b are schematic sectional views of a first embodiment of the deep drawing tool according to the invention;

Figures 2a, 2b and 2c are schematic representations of the force relationships in the deep drawing tool shown in Figures 1a and 1b;

Figures 3a and 3b are schematic sectional views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 4a and 4b are schematic sectional views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 5a and 5b are schematic sectional views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 6a and 6b are schematic sectional views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 7a and 7b are sectional views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 8a and 8b are different section views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 9a and 9b are different section views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 10a and 10b are different section views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement;

Figures 11a, 11b and 11c are different section views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement.

Figures 12a, 12b and 12c are different section views of another embodiment of the deep drawing tool according to the invention in different positions of the deep drawing movement; and

Figure 13 is a sectional view of another embodiment of the deep drawing tool according to the invention.

Figures 1a and 1b show a first embodiment of a deep drawing tool 100 according to the invention for deep drawing blanks from sheet metal to form blanks. The deep drawing tool 100 comprises a drawing core 102 and a drawing bell 104, which are linearly movable relative to each other. During this linear movement, the drawing bell 104 can move towards the drawing core 102 in such a way that the drawing bell 104 and the drawing core 102 are inserted into each other, as shown in Figures 1a and 1b . In the embodiment illustrated here, the drawing core 102 is arranged stationary and the drawing bell 104 is lowered onto the drawing core 102 in a linear downward movement until it at least partially surrounds the core. drawing core 102. However, the present invention is not limited to embodiments with the drawing core 102 stationarily attached. Rather, the drawing bell 104 can also be arranged stationarily and the drawing core 102 is raised in the direction of the drawing bell 104. Furthermore, embodiments are conceivable in which the drawing bell 104 is located in the lower part and the drawing core 102 is arranged above. Furthermore, the above-described relative approaching movement of the drawing bell 104 and the drawing core 102 is reversible, so that they can be removed from each other again and separated.

The approaching movement of the drawing bell 104 and the drawing core 102 is referred to below as deep drawing movement. It serves to deep draw a blank formed from the blank 106. For this purpose, the blank 106 is arranged on the side of the drawing core 102 facing the drawing bell 104. By the deep drawing movement , the lower edge area 108 of the drawing bell 104 receives the radially outer edge of the blank 106 and draws it deeply above the drawing bell 104. To do this, it is necessary to secure the outer edge of the workpiece in rough 106. This is done by means of a holder 110, which is arranged as counter support for the lower edge area 108 of the drawing bell 104 below it. The fastener 110 is pressed upwards towards the drawing bell 104 by a pin 112. To do this, the pin 112 is pressed on its lower side by means of a spring 114. In this way, the radially outer edge of the part blank 106 is trapped between the edge area 108 of the drawing bell 104 and the upper side of the holder 110.

A cutting ring 116 is also arranged radially on the outside of the holder 110, on which a radially outermost edge 118 of the blank 106 rests in plane. When the drawing bell 104 is lowered, this outermost edge 118 is lowered. cuts from an edge region of the blank 106 located radially further inward.

The drawing bell 104 is represented in Figures 1a and 1b, as well as in the following figures in longitudinal section, the section plane being in the axis of movement of the linear deep drawing movement. In the horizontal cross section (perpendicular to the drawing plane), the drawing bell 104 has a cross section adapted internally to the desired shape of the blank, for example, circular, rectangular or oval, just like the drawing core. 102. In this way, the drawing core 102 and the drawing bell 104 are arranged concentrically. The fastener 110 is correspondingly arranged around the drawing core 102 and surrounds it.

The drawing bell 104 has an upper part 120, the upper side of which is here closed by a flat cover area 122, a radially outer part 124 which is arranged below the upper part 120 and is connected to the latter, and a part radially inner portion 126 which is disposed radially within the radially outer portion 124. For simplicity, the radially outer portion 124 will hereinafter be referred to as the outer portion 124 of the drawing bell 104 and, correspondingly, reference will be made to the radially inner part 126 as the inner part 126.

The inner portion 126 is movable relative to the outer portion 124. In the present embodiment, the inner portion 126, which has an approximately cylindrical configuration, is movable along its cylinder axis relative to the outer portion 124. In Figure 1a, the inner part 126 occupies a lower stop position, in which an annular stop 128 on the radially outer side of the inner part 126 rests on a corresponding stop 130, which is formed by an inner graduation of the outer part 124. In this lower stop position, the lower sides of the inner part 126 and the outer part 124 are flush with each other.

From this stop position in Figure 1a, the inner part 126 can move upward to a top stop position, in which the annular stop 128 can move against an upper stop 132 on the inner bottom edge of the top 120. In this way, the stops 130 and 132 limit an axial displacement movement of the inner part 126. In the upper stop position shown in Figure 1b, the lower side 134 of the inner part 126 is raised with respect to the lower side 136 of the outer part 124.

The stops 130 and 132 on the outer part 124 and the annular stop 128 on the inner part 126 represent coupling means, by which the outer part 124 and the inner part 126 of the drawing bell 104 are coupled during a section of the deep drawing movement. In the present case, this means that the outer part 124 and the inner part 126 are joined as a single piece to each other by this coupling and perform the same movement. This deep drawing movement (in the present embodiment of the drawing bell 104 downwards) occurs against the supporting counterforce of the fastener 110 from below, which is generated by the spring 114. The coupling means further comprises means to exert a retaining force on the inner part 126, by means of which it is pressed downwards against the lower stop 130 of the outer part 124. These means for exerting a retaining force are not represented in figures 1a and 1b, but they will be explained later with reference to other embodiments. In particular, these means may comprise an additional spring by which the inner part 126 is pressed downwards against the stop 130 of the outer part 124.

At a predetermined point in the deep drawing movement, the coupling means cancel the coupling. This means that the outer part 124 and the inner part 126 no longer move together, but rather the inner part 126 can carry out a relative movement with respect to the outer part 124. In particular, it is an upward movement, 1b, by which the annular stop 128 of the inner part is disengaged from the stop 130 of the outer part 124. At the same time, the lower side 134 of the inner part 126 is raised relative to the side lower 136 of the outer part 124. This release of the coupling of the inner part 126 with the outer part 124 can be carried out by means that nullify or reduce the retention force on the inner part 126. These means may comprise a drive to move the inner part 126 with respect to the outer part 124, in the present embodiment upward, or they can make the inner part 126 completely free to move with respect to the outer part 124 and, thus, be able to avoid a force that act from below axially upwards.

Preferably, the coupling between the inner part 126 and the outer part 124 is canceled at a point in the deep drawing movement at which the blank 106 is deep drawn to such an extent that only a residual lip 138 remains between the underside 134 of the inner part 126 and the fastener 110. As the coupling is released, the underside 136 of the outer part 124 can therefore abut directly against the fastener 110 and press it further downward against the force of the spring 114. Meanwhile, due to the nullification of the coupling, the interlock between the underside 134 of the inner part 126 and the fastener 110, by which the residual flange 138 is held, is completely nullified or its interlocking force is greatly reduced. If the deep drawing movement is then continued, the residual flange 138 can be completely stretched between the inner wall of the outer part 126 and the cylindrical outer wall of the drawing core 102 without lacquer filaments forming on the residual flange 138. remaining.

According to the invention, therefore, it is only necessary to reduce the holding force on the inner part 126 of the drawing bell 104 to avoid the supporting counterforce by the fastener 110. This is a significant advantage with respect to tools of deep drawing known from the state of the art, in which the support counterforce must be completely nullified.

Figures 2a, 2b and 2c explain the force relationships in more detail with the help of schematic diagrams.

These figures contain in each case an enlarged representation of the edge area 108 of the drawing bell 104, including the lower sides 136, 134 of the inner part 126 and outer part 124, in each case, of the drawing bell 104, of the upper area of the fastener 110 and the upper parts of the drawing core 102 and the outer cutting ring 116. The blank 106 is also shown in different positions during the deep drawing movement.

In Figure 2a, the residual lip 138 of the blank 106 is wedged between the bottom sides 134, 136 that end flush with each other of the inner part 126 and the outer part 124. The force exerted from above by the outer part 124 is indicated by F2, and the force exerted in the same direction by the inner part 126 is indicated by F4. From below, the supporting counterforce F1 acts through the holder 110 in its radially outer part, which is axially opposite to the outer part 124 of the drawing bell 104, as well as an additional force component F1a, possibly parallel to this, in an area in which the fastener 110 can exert an axial pressure on the inner part 126. Furthermore, a force F3v acts upward as a vertical component of a force F3, which acts on a rounded inner edge area 140 of the inner part 126 due to the counterforce of the material of the blank 106. F1a may be very small or equal to zero if this rounded edge area 140 extends so much radially outward in the direction of the outer part 124 that it does not extend exerts no further supporting counterforce directly through the fastener 110 upward onto the inner portion 126.

It results from this:

F4 = F3v Fla,

It could be that F1a = 0.

Therefore, the holding force F4 on the inner part 126 must be applied to release the latch in the radially inner area of the drawing bell 104. It is considerably lower than a total force F5, which would have to be applied to counteract the entire counterforce of support from below and which can be equated to

F5 = F1 Fia,

It could be that F1a = 0.

Figures 2b and 2c represent how the force F4 is greatly reduced or completely eliminated to override the interlock. During the deep drawing process, this preferably takes place in a situation in which the residual flange 138 is shortened radially inwards to such an extent that it is located only between the radially inner part 126 and the radially inner lower edge of the fastener 110. On the contrary, the outer part 124 abuts directly against the upper side of the fastener 110, so that the fastener 110 can be pressed further downward. As the force F4 through the inner portion 126 is reduced or eliminated, the residual lip 138 is released and is no longer secured. If the deep drawing movement is continued from the position of Figure 2b when the inner and outer parts are engaged again (Figure 2c), the residual rim 138 can be fully stretched. The formation of lacquer filaments on the residual rim 138 is prevented.

Figures 3a and 3b show an embodiment of the deep drawing tool 200 according to the invention, in which the drawing bell 204 is configured similarly to the preceding embodiment of the deep drawing tool 100. Accordingly, the drawing bell 204 comprises a top portion 220, an outer portion 224 axially adjoining below, and a radially inner portion 226.

Figure 3a shows a coupling position in which the inner part 226 is coupled with the outer part 224, so that together with the upper part 220 they can execute the downward deep drawing movement of the drawing bell 204. These coupling means comprise the annular stop 228 on the radially outer side of the inner part 226 and a step-shaped stop 230 on the inner side of the outer part, comparable to the stop 130 of Figures 1a and 1b.

The stop 228 of the inner part 226 is pressed down against the stop 230 of the outer part 224 by a compression spring 250, which is located between the upper edge 252 of the inner part 226 and a spring support 254. The edge Upper 252 forms a first stop 252 for compression spring 250, while spring support 254 forms a counter support. In the engaged position of Figure 3a, the compression spring 250 presses the radially inner part 126 downward, so that the stop 228 collides with the stop 230.

To disengage the inner part 226 and the outer part 224, the counter support 254 formed by the spring support is moved upward by an actuation not shown in detail, that is, away from the first stop 252. As a result, the compression spring 250 relaxes and the compression force pressing the inner part 126 downward is reduced. In the embodiment shown here, the spring support 254 is moved by the drive upward until the inner part 226 collides with its stop 228 against an upper stop 232 on the lower inner edge of the upper part 220. The drive stops Moving the spring support 254 upward thus cancels the retention force that presses the inner part 226 to a fixed position with respect to the outer part 224. In the position of Figure 3b, a new coupling occurs between the inner part 226 and the outer part 224, with which the deep drawing movement can continue.

The provision of the compression spring 250 and the spring support 254 as means for holding the inner part 226 in the engaging position, as well as a drive for raising the spring support 254 to nullify or reduce the holding force, can be combined with the embodiment of the deep drawing tool 100 of Figures 1a and 1b. Additionally, this embodiment can also operate with a pneumatic compression spring, which replaces the mechanical compression spring 250 shown here. In this case, the spring support 254 is replaced by a piston that limits the volume of the pneumatic compression spring. The piston therefore acts here as a counter support for the pneumatic compression spring. If the piston is lifted by the drive, the pneumatic compression spring relaxes.

An alternative embodiment of the deep drawing tool 300 is shown in Figures 4a and 4b, which is equipped with means for holding the inner part 226 in the engaging position and with means for canceling or reducing the holding force. . The design of the individual parts of the drawing bell, including its upper part 320, the radially outer part 324 located below and the radially inner part 326, corresponds to the drawing bell 204 of Figures 3a and 3b, as well as that the annular outer stop 328, the step-shaped stop 330 of the outer part 324 and the stop 332 of the upper part 320, between which the stop 328 can move up and down.

Within the upper part 320, a compression spring 350 is located between the flat cover area 322, which closes the drawing bell 304 at the top, and a spring support 354 arranged below. This spring support 354 here rests directly (alternatively also indirectly) on the upper edge of the inner part 326 and forms a counter support for the compression spring 350. This upper edge forms a third stop 352, through which the pressure of the compression spring 350 can be transmitted to the inner part 326 through the spring support 354 and thus exert a force for holding the inner part 326 in the engaging position. On the other hand, the cover area 322 forms a second stop 356 for the compression spring 350, which is coupled to the outer part 324 for movement.

In Figure 4a, the spring support 354 is in a lower position in which the inner part 326 is engaged with the outer part 324, since the annular stop 328 is in contact with the stop 330. This coupling can be canceled by moving , by means of an actuation not shown in detail, the spring support 354 upwards and compressing the compression spring 350. In the position of Figure 4b a new coupling is achieved between the inner part 326 and the outer part 324 upon impact the stop 328 against the stop 332. Between these positions, the inner part 326 and the outer part 324 are decoupled from each other.

The means for overriding or reducing the retention force of the compression spring 350 here therefore comprise the drive, which moves the spring support 354 upward and releases the inner part 326 from the pressure of the compression spring 350. Analogous to the previous embodiment of Figures 3a and 3b, a pneumatic compression spring can also be used here instead of a mechanical compression spring 350, replacing the spring support 354 with a piston as a counter support. The piston exerts pressure on the inner part 326. When the piston is raised by an actuation, the volume of the pressure chamber of the pneumatic compression spring is compressed and the pneumatic compression spring is tensioned, while the inner part 326 is unloaded .

Figures 5a and 5b show another embodiment of a deep drawing tool 400, with a deep drawing bell 402, comprising an upper part 404, a radially outer lower part 424 and a radially inner part 426. An annular outer stop 428 of the inner part 426 is located between a lower stop 430 on the inner side of the outer part 424, corresponding to the stop 330 of the preceding embodiment of the deep drawing tool 300, and an upper stop 432 is arranged on the radially inner bottom edge of the upper part 420 corresponding to the position of the stop 332. As in the preceding embodiment of the deep drawing tool 300, a compression spring 450 is arranged between a second stop 456 on the lower side of the flat cover area 422 and a spring support 454 that rests on a third stop 452 that is formed by the upper edge of the inner part 426. The spring support 454 is thus pressed down on the radially inner part 426 by the compression spring 450, so that a retention force is exerted on the inner part 426 to retain it in a fixed position relative to the outer part 424, in which the stop 428 is held against the stop 430. Analogous to the preceding embodiment in Figures 4a and 4b, the spring support 454 forms a counter support for the compression spring 450.

In the present embodiment, the spring support 454 has a radially outwardly projecting drive element 458, which extends through the cylindrical wall of the upper part 420 of the drawing bell 404. A fourth stop 460 It is statically arranged outside the drawing bell 404, namely in a position in the movement path of the driving element 458 during a downward movement of the drawing bell 404.

During the deep drawing movement, the driving element 458 of the spring support 454 receives the fourth stop 460. Therefore, the spring support 454 is pressed upwards, i.e. in the direction of the second stop 456 in the cover area. 422, so that the inner part 426 is released from the holding force. This situation is represented in Figure 5b. Therefore, the stop 428 is released from the stop 430, so that the inner part 426 is released and its coupling with the outer part 424 is canceled. Analogously to Figures 4a and 4b, the mechanical compression spring 450 can be replaced by a pneumatic compression spring, and a piston acts as a counter support in place of the spring support 454, which, like the spring support 454 described above, it is equipped with a driving element 458. Therefore, the lifting of the piston causes compression of the pneumatic compression spring here as well.

Figures 6a and 6b show an embodiment of the deep drawing tool 500 with a drawing bell 504, the structure of which is comparable to the drawing bell 404 of the deep drawing tool 400 and which, consequently, comprises a part top 502, a radially outer part 524 arranged below and a radially inner part 526. The arrangement of the stop 528 in the radially inner part 526 and of the stops 530 and 532 in the radially outer part to limit the movement of the stop 528 corresponds to the embodiment of the deep drawing tool 400. Also corresponding is the arrangement of a spring support 554 as counter support, which is pressed downwards against the upper edge of the inner part 526, which forms a third stop 552, by a compression spring 550 arranged above, which rests upwards against a second stop 556 in the cover area 522 of the upper part 520. Here again, the spring support 554 has a driving element 558 protruding from the cylindrical outer wall of the upper part 520 and which collides with a fourth stop 560 during the deep drawing movement.

In the present embodiment, however, the fourth stop 560 is not static, but is arranged on a vertically movable spacer 564 and is attached to an area that protrudes radially outward from the top 520 of the drawing bell. 504 through an additional compression spring 562. In the coupling position of the inner part 526 to the outer part 524 shown in Figure 6a, the driving element 558 has a distance with respect to the fourth stop 560, which is maintained by the compression spring 562.

Figure 6a shows a position of the deep drawing movement in which the separator 564 already collides with a stop and can no longer move. By the additional axial movement of deep drawing of the drawing bell 504, it moves downwards with respect to the spacer 564, and the driving element 558< of the spring support 554 receives the fourth stop>560< and is pressed towards above, as shown in figure>6b. Therefore, the force of the compression spring 550 on the inner part 526 is reduced or eliminated, so that the retention force to retain the inner part 526 in the engagement position on the outer part 524 is reduced or eliminated.

As in the preceding embodiments, also in the embodiment of Figures 6a and 6b the compression spring 550 and also the compression spring 562 can optionally be formed by mechanical springs or pneumatic springs. In this case, the spring support 554 is replaced by a piston as a counter support. On the upper and lower stop surfaces of the compression spring 562, corresponding piston surfaces are to be provided, which delimit a corresponding pressure chamber.

Figures 7a and 7b show a further embodiment of the deep drawing tool 600 according to the invention with a spacer 664, the upper edge of which forms a fourth stop 660, which is comparable to the fourth stop 560 of the embodiment precedent of the deep drawing tool 500, but which is arranged within the drawing bell 604. The drawing bell 604 has a similar structure to the drawing bell 504 of Figures 6a and 6b, and comprises an upper part 620, an outer part 624 arranged below and an inner part 626 which is located between the outer part 624 and the separator 664. The arrangement of the outer stop 628 in the inner part 626 corresponds to that of the stop 528 of figures 6a and 6b, that is That is, the stop 628 is arranged between the upper and lower inner stops 630 and 632 of the outer part 624, so that the inner part 626 is movable up and down between the stops 630 and 632.

The spring support 654 is pressed down on the upper edge of the inner part 626 by a compression spring 650, so that the inner part 626 is held in its engagement position on the outer part 624. The arrangement of the spring compression 650 between the second stop 656 in the cover area 622 of the upper part 620 and the spring support 654 corresponds to figures 5a and 5b, in such a way that the spring support 654 is pressed on the upper edge of the part interior 626 as the third stop 652 and, thus, a downward holding force is exerted to retain the interior part 626 in the engaging position on the exterior part 624, in which the stop 628 bears against the stop 630 .

While a radially outwardly projecting portion 670 of the spring support 654 extends into an opening 672 within the cylindrical wall of the upper part 620 and is guided therein, a radially inwardly projecting portion 674 of the spring support 654 protrudes from the fourth stop 660 on the spacer 664. In the position of Figure 7a, a compression spring 662 holds the fourth stop 660 at a distance from the inwardly protruding part 674 of the spring support 654. During movement of deep drawing, the spacer 664 reaches a fixed stop position and approaches the protruding part 674 of the spring support 654, whereby the spring support 654 receives the fourth stop 660 during the subsequent deep drawing movement and is pressed upwards, that is, in the direction of the second stop 656.

Therefore, the coupling between the inner part 426 and the outer part 624 is canceled, similar to the embodiment of the deep drawing tool 500 of Figures 6a and 6b. The main difference compared to the deep drawing tool 500 is that in this case the fourth stop 660 arranged on the spacer 664 is not arranged outside, but inside the drawing bell 604.

As in the previous embodiment, the compression springs 650 and 662 may each be formed by pneumatic springs. While in the representation described above the spring support 654 forms a counter support for the compression spring 650, in the case where a pneumatic spring is used, this counter support can be formed by a piston that is used instead of the spring support 654.

Figures 8a and 8b show a further embodiment of the deep drawing tool 700 according to the invention, the drawing bell 704 of which in turn has a substantially cylindrical upper part 770 with a cover area 722 that closes the interior of the drawing bell 704 at the top, as well as a lower outer part 724 and an inner part 726, which are structured like the outer and inner parts 624, 626 of the deep drawing tool 600 of Figures 7a and 7b , including the outer stop 728 in the inner part 726, which is movable between the lower stop 730 in the outer part 724 and another stop 732 located above in the upper part 720. Also in the present embodiment, the inner part 726 It is pressed down against the stop 730 by a holding force, so that the inner part 726 can occupy a fixed engaging position with respect to the outer part 724 during the deep drawing movement. In the present case, the means for exerting such a retaining force comprise a pneumatic spring 750 comprising a piston 752 that is movable up and down as counter support within the drawing bell 704 between the upper edge 754 of the inner part 726 and the cover part 722. The piston 752 is sealed towards the inner cylindrical wall of the upper part 720 by an O-ring 756.

Above the piston 752 is a space 758 inside the drawing bell 704, which is open to the outside through a radial opening 760 in the cylindrical outer wall of the upper part 720 and can be subjected to compressed air through a valve (not shown). This compressed air drives the piston 752 downwards directly or indirectly (i.e., for example, through a coupling element not shown here) against the upper edge 754 of the inner part 726.

Through the valve, the inner chamber 758 can be pressurized on the one hand, but on the other hand can also be vented to reduce or eliminate the holding force on the inner part 726 against the stop 730. The valve provides this mode a means to nullify or reduce the retention force by which the outer and inner parts 624, 626 are held in their mating position.

The deep drawing tool 800 of Figure 8b further comprises a pneumatic spring cushion 850 with a piston 852, which is constructed like the piston 752 of Figure 8a and is arranged as a counter support, so that also in this case the space 858 between the upper side of the piston 852 and the cover area 822 of the upper part 820 can be pressurized or vented through a radial opening 860. The arrangement of the inner part 824 and the outer part 826 corresponds to that of the inner part 724 and the outer part 726 of Figure 8a.

However, departing from the preceding embodiment of Figure 8a, the piston acts on a pin 864 that extends vertically downward through an opening 866 in a bottom 867 of the upper part 820 of the drawing bell 804. The pin 864, in turn, presses the upper edge 854 of the inner part 826 of the drawing bell 804 downward, so that an outer radial stop 828 on the inner part 826 abuts a stop 830 on the inner side of the outer part 824. An upper stop 832 on the lower inner edge of the upper part 820 limits the upward movement of the stop 828.

Figure 8b shows a sectional view in which only one pin 864 can be seen. Preferably, several pins can be arranged along the annular upper edge 854.

A difference with respect to the deep drawing tool 700 of Figure 8a is that the piston 852 does not act directly on the inner part 826 and presses it downwards, as is the case in Figure 8a, so that the holding force It is exerted through pin 864.

Figures 9a and 9b show a further embodiment of a deep drawing tool 900 according to the invention with a drawing bell 904 which, like the drawing bell 804, has an upper part 920, an outer part 924 arranged below and an inner part 926 that is arranged axially displaceable with respect to the outer part 924. In the manner already described, the inner part 926 can be coupled to the outer part 924 through a radially outer stop 928, the which has an internal stop 930 against which the stop 928 can abut.

To exert a holding force, which presses the inner part 926 downwards against the stop 930 of the outer part 924, a driving element 950 serves in this case, which is kept movable vertically within an opening 952 in the outer wall. cylindrical part of the upper part 920. The driving element 950 rests with its inner end on the upper edge 954 of the inner part 926, so that in a lower position of the driving element the inner part 926 is maintained in the coupling position with the outer part 924, in which the stops 928 and 930 rest on each other.

In this position, shown in Figure 9a, the driving element 950 is held by a magnetic force. The opening 952, in fact, is designed as an electromagnetic support with switchable polarity. The position of Figure 9a corresponds to a first switching position in which the driver 950 is magnetically attracted to the lower side 956 of the opening 952. When switching the switching position, the driver 950 is repelled by this lower end 956 and moves in the direction of the upper end 958, as shown in Figure 9b. This cancels out the holding force, which presses the inner portion 926 downward against the stop 930. The inner portion 926 is then disengaged from the outer portion 924 and can be moved upward. In the position of Figure 9a, the drive element 950 is attracted by the upper end 958 of the magnetic holder and occupies a second axial position, which is linearly displaced upward relative to the first axial position of Figure 9a. Accordingly, the inner part 926 rests against an upper stop 932 on the lower inner edge of the upper part 920 of the drawing bell 904.

The driving element 950 thus represents an embodiment of the coupling means by which the inner part 926 can be coupled to the outer part 924 of the drawing bell 904. Switching the polarity of the magnetic holder of the first switching position in Figure 9a to the second switching position in Figure 9b can take place when the predetermined point of the deep drawing movement is reached at which the inner part 926 must be released.

Figures 10a and 10b show a further embodiment of a deep drawing tool 1000 according to the invention with a drawing bell 1004 which, like the preceding embodiments, has a substantially cylindrical upper part 1020, a radially outer part 1024 arranged below and a radially inner part 1026. The inner part 1026 is axially displaceable with respect to the outer part 1024, an outer stop 1028 being provided on the radially inner part 1026 to abut against an inner stop 1030 of the radially outer part 1024, so that the outer part 1024 and the inner part 1026 couple together, as shown in Figure 10a.

In this engaging position, the inner portion 1026 is supported by a drive member 1050 that extends radially through an opening 1052 in the cylindrical wall of the upper portion 1020 and is movable radially outwardly and inwardly. A beveled stop surface 1054 at the radially inner end of the driver 1050 rests on a corresponding upper stop surface 1056 of the inner part 1026. When the driver 1050 is in the inwardly offset position of Figure 10a , its beveled stop surface 1054 presses the inner part 1026 downwards and, therefore, the stop 1028 against the stop 1030, so that coupling between the inner part 1026 and the outer part 1024 is achieved.

In this position, the drive member 1050 is held by a cam track 1058, which is stationarily arranged outside the drawing bell 1004. During the deep drawing movement, the drawing bell 1004 moves along This cam track 1058 such that the drive member 1050 is pressed radially inward by an inner surface 1060 of the cam track 1058 directed toward the drawing bell 1004. The radially outer end 1062 of the drive member 1050 is then slides on this inner surface 1060 of the cam track 1058.

At a predetermined point of the deep drawing movement, the outer end 1062 of the driving element 1050 reaches a lower end 1064 of this surface 1060 and is released for an outward movement, as shown in Figure 10b. Due to the outward displacement of the drive element 1050 shown there, its stop surface 1054 also moves outward and releases the inner part 1026 for upward movement, so that the engagement between the inner part 1026 and the outer part 1024 is annulled. The inner part 1026 can then be moved up to an upper inner stop 1032 on the lower inner edge of the upper part 1020 of the drawing bell 1004, so that a new coupling of the inner part 1026 with the outer part 1024 is achieved. a position in which the inner part 1026 is displaced upward with respect to the outer part 1024.

Figures 11a, 11b and 11c show an embodiment of the deep drawing tool 1100 according to the invention, in which the deep drawing bell 1104 has, in addition to the upper part 1120 and the outer part 1124 arranged below , a first radially inner part 1126 and a second radially inner part 1128, the first inner part 1126 being arranged between the outer part 1124 and the second inner part 1128. The arrangement of the first inner part 1126 with respect to the outer part 1124 corresponds to that of the outer part 224 and the inner part 226 of the deep drawing tool 200 of Figures 3a and 3b, also with respect to the means for exerting a retaining force on the first inner part 1126 to hold it in a position of fixed coupling with respect to the outer part 1124. A radially outer stop 1130 of the first inner part 1126 is linearly displaceable between a lower inner stop 1132 and an upper stop 1134 on the upper part 1120 of the drawing bell 1104. The Stop 1130 is pressed downward against stop 1132 by a compression spring 1150, which is pretensioned between a first stop 1152 that is formed by the upper edge of the first inner part 1126 and a spring support 1154. The action of the spring compression 1150 and of the spring support 1154 is the same as that of the compression spring 250 in the spring support 254 of the deep drawing tool 200, that is, the spring support 1154 can move upward as a counter support of the spring compression 1250 to reduce or eliminate the retention force in the first inner part 1126.

The second inner part 1128 is coupled with the first inner part 1126 by a driving element 1156, which is radially displaceable in the first inner part 1126 between a pushed inward position, as shown in Figure 11a, and a pushed position outwards (figure 11c). In the pushed-in position, the driving element 1156 forms a stop for the second inner part 1128 on its lower side, so that it rests against the driving element 1156 from below and cannot be moved in turn. further upward in relation to the first inner part 1126. In this way, the first inner part 1126 and the second inner part 1128 are coupled to each other. In this way, the compression spring 1150 pushes the first inner part 1126 and the second inner part 1128 as a unit downward to the engaging position defined by the stop 1132 and holds them in this position.

When a predetermined point of the deep drawing movement is reached, the engagement between the first inner portion 1126 and the outer portion 1124 may first be released by first moving the drive spring support 1154 upward. This situation is represented in figure 11b. The position of the driving element 1156 remains unchanged, so that the coupling between the first inner part 1126 and the second inner part 1128 and their position relative to each other is maintained.

At another subsequent moment of the deep drawing movement, the coupling between the first inner part 1126 and the second inner part 1128 can be canceled by pushing the driving element 1156 towards the outside, that is, towards the inside of the first inner part 1126. In this way, the second inner part 1128 can be moved upwards. If necessary, in this way an additional stop position 1157 in the form of an inner step is achieved on the upper inner edge of the second inner part 1128 and thus a coupling of the first inner part 1126 and the second part interior>1128<in a further engaging position, in which the second interior part>1128<is elevated with respect to the first interior part 1126.>

As in the preceding embodiments, in particular, as in the arrangement of the embodiment of Figures 3a and 3b, the compression spring 1150 can also be replaced here by a pneumatic spring or the like. While, in the arrangement described above with a mechanical compression spring, the spring support 1154 forms the counter support for the compression spring, when a pneumatic compression spring is used, the spring support 1154 can be replaced by a piston such as counter support, through whose upward and downward movement the pressure of the compression spring 1150 can be modified.

Figures 12a, 12b and 12c show another embodiment of a deep drawing tool according to the invention with a drawing bell 1204 having an outer part 1224, a first inner part 1226 and a second inner part 1228. As in In the preceding embodiments, the first inner part 1226 is movable up and down with respect to the outer part 1224, these two parts 1224 and 1226 being engageable with each other up to a predetermined point of the deep drawing movement.

A compression spring 1250 is arranged between the upper edge 1252 of the first inner part 1226 and a spring support 1254 arranged above, and a further compression spring 1256 is arranged between the spring support 1254 and a cover area 1222 of the drawing bell 1204 arranged above. In this way, the spring support 1254 can be raised upward against the pressure of the compression spring 1256, thereby reducing the pressure of the compression spring 1250 on the first inner part 1226 located below.

The second inner part 1228 is coupled to the first inner part 1226 through a stop ring 1231. In detail, the second inner part 1228 has an inner step that forms a lower stop 1230 on which the lower side of the ring rests. stop 1231 in the position of Figure 12a. A radially outer step 1232 is also provided at the lower end of the stop ring 1231, on which a radially inwardly directed step 1234 of the first inner part 1226 rests. Therefore, the second inner part 1228 can only be push upward until its stop 1230 abuts against the lower side of the stop ring 1231 and its step 1232 abuts against the stop 1234 of the first inner part. Therefore, the upward displacement path of the second inner part 1228 with respect to the first inner part 1226 is limited.

In this coupling position of the second inner part 1228 with the first inner part 1226, their lower sides 1236 and 1240 are flush with each other. In the position of Figure 12a, they are also flush with the underside 1242 of the outer part 1224. Thus, a uniform underside of the drawing bell 1204 is formed, which presses the residual rim 1244 of the blank 1246 down against fastener 1248.

In Figure 12b, the deep drawing movement is more advanced and the residual lip 1244 is only between the first inner part 1226 and the second inner part 1228, while the underside 1242 of the outer part 1224 presses directly against the fastener 1248. At this point of the drawing movement, the coupling of the first inner part 1226 with the outer part 1224 can be canceled by raising the spring support 1254 against the pressure of the compression spring 1256. As soon as the force of the compression spring 1250 is below the retention counterforce of the fastener 1248 (see Figure 2b; F4 < F1 F1a), the fastener 1248 collides with the outer part 1224. In this position a new coupling occurs between the first inner part 1226 and the outer part 1224, namely in a position axially displaced by the material thickness of the residual flange 1244. The residual flange 1244 is now locked with a newly metered and reduced locking force by the elongated compression spring 1250. This new locking force can be transmitted to the second inner part 1228 through the step 1234 and the stop 1232. That is, the first inner part 1226 and the second inner part 1228 remain engaged with each other after the override and restoration of the coupling between the first inner part 1226 and the outer part 1224, in which their lower sides 1236 and 1240 remain flush with each other.

Up to this point, the deep drawing movement has been carried out in a similar way to the embodiment of Figure 3b: the compression spring 1250 (250 in Figure 3b) has been lengthened, a decoupling of the inner part has occurred 1226 (226 in Figure 3b) and, in the same way, a new coupling of the inner part 1226 (226 in Figure 3b) in an axially displaced position, although here in Figure 12b in connection by force drag by pressing on the residual flange 1244 and not by dragging as in figure 3b by the stop 232. Figures 12a and 12b thus show a deep drawing process of blanks with residual flange, the initial locking force on the residual flange 1244 by disengaging and re-engaging an inner drawing bell piece and being able to be metered again for the residual flange that has become smaller.

Figure 12c shows how this embodiment of the deep drawing tool can be used to avoid lacquer filaments if the residual flange 1244 is to be fully stretched, similar to the principle presented in Figure 4b. As soon as in the further course of the deep drawing movement the residual rim 1244 has been reduced in size to the point that it is only in contact with the underside of the second inner part 1240, the first inner part 1226 of the bell drawing is disengaged in order to nullify the locking force and the second inner part 1228 is re-engaged with the outer part of the drawing bell 1224 in order to completely stretch the residual rim without the formation of lacquer filaments.

Decoupling:

Since the spring support 1254 is held stationary by reaching a stationary stop at the position of Figure 12b during the subsequent deep drawing movement to the position of Figure 12c, a stop 1272 at the upper end of the stop ring 1231 It collides with a radially inner stop 1274 on the spring element 1254, and also remains stationary during the subsequent deep drawing movement. In this way, the radially outer step 1232 of the stop ring 1231 is made to abut the radially inner stop 1234 of the first inner part 1226, whereby the first inner part 1226 also remains stationary. The stop ring 1231, which is indirectly acted upon by the compression spring 1250, is in this respect similar in function and movement to the spring support 354 of Figures 4a and 4b. The retaining force on the second inner drawing bell part 1228 is canceled by the contact of the spring element 1254 with the stop ring 1231.

New coupling:

The counterforce acting on the drawing core 1202 through the residual rim 1244 and its inner drawing radius also holds the second inner part 1228 of the drawing bell immobile in the same way as the first inner part 1226 until, when continued the deep drawing movement, the second inner part 1228 is coupled again to the outer part 1224 or its cover area 1222 through a stop 1270 at its upper end.

A further continuation of the deep drawing movement from the situation of Figure 12c causes the residual lip 1244 to extend completely downward over the drawing core 1202.

In the embodiment of Figures 12a, 12b and 12c, each of the compression springs 1250 and 1256, which are arranged on both sides of the spring support 1254 as counter support for the respective springs, can be replaced by a compression spring. pneumatic compression. In particular, the spring support 1254 can be replaced in this case by a piston which separates the respective pressure chambers of the pneumatic compression springs 1250 and 1256 from each other and which is movable up and down.

Figure 13 shows another embodiment of the deep drawing tool 1300 according to the invention, which is constructed similarly to the deep drawing tool 800 of Figure 8b, but comprising an extension thereof. In detail, the deep drawing tool 1300 also comprises a drawing bell 1304 with an upper part 1320, an outer part 1324 arranged below and an inner part 1326. The outer part 1324 and the inner part 1326 of the drawing bell 1304 They are constructed as, in each case, the outer part 824 and the inner part 826 of the deep drawing tool 800, including the outer stop 1328 in the inner part 1326, corresponding to the stop 828, the stop 1330, corresponding to the stop 830, and the upper stop 1332 on the inner lower edge of the upper part 1320, the stop 1328 being movable up and down between the stops 1330 and 1332.

Also coincident with the deep drawing tool 800 is the arrangement of a piston 1352 within the upper part 1320 and of pins 1364 that extend vertically downward through openings 1366 in the bottom 1367 of the upper part 1320 of the bell. drawing 1304. The piston 1352 acts vertically downwards on the upper ends of the pins 1364 and they, in turn, press on the upper edge of the inner part 1326.

In this way, a pressure acting downward on the piston 1352 is transmitted to the inner part 1326 through the pins 1364.

Above the piston 1352 there is a space 1358 within the drawing bell 1304, which is limited upwardly by the cover area 1322 of the upper part 1320. Unlike the deep drawing tool embodiment 800 of the Figure 8b, the space is divided by another piston 1370 into a first pressure chamber 1372 and a second pressure chamber 1374. The first pressure chamber 1372 is located below the additional piston 1370 and is delimited by its lower side and the upper side of the piston 1352 described above. The second pressure chamber 1374, located above, is delimited by the upper side of the additional piston 1370 and the cover area 1322. The additional piston 1370 can move up and down. An upward movement increases the volume of the first pressure chamber 1372 and the volume of the second pressure chamber 1374 decreases accordingly. On the contrary, a downward movement of the additional piston 1370 increases the volume of the second pressure chamber 1374 and reduces the volume of the first pressure chamber 1372.

Both pressure chambers 1372 and 1374 can be pressurized, in each case, with compressed air through the radial openings 1376, 1378, which extend through the cylindrical outer wall of the upper part 1320.

If the additional piston 1370 is lowered and the size of the first pressure chamber 1372 is reduced, the pressure inside the first pressure chamber increases (when the opening 1376 is closed). This pressure acts from above on the piston 1352, which presses downwards on the pins 1364 and thus transmits the pressure to the inner part 1326 of the drawing bell 1304. This allows a holding force to be exerted. Conversely, if the additional piston 1370 is raised and the pressure within the pressure chamber 1372 is reduced, the holding force is reduced. The movement of this additional piston 1370 can be carried out by a corresponding drive, by means of a driving element on the piston 1370, which hits a stop during a movement of the drawing bell 1304, or the like. In this case, the second pressure chamber 1374 serves to maintain a pressure that keeps the piston 1370 in equilibrium.

The pressure chambers 1372 and 1374 thus form pneumatic spring cushions 1350, which can perform, for example, the function of the springs 1250 and 1256 of the deep drawing tool 1200 of Figures 12a, 12b and 12c and can replace them in a correspondingly constructed embodiment. In this case, piston 1370 forms the counter support for the two air compression springs and replaces spring support 1254.

In all embodiments shown in which compression springs are used, mechanical compression springs, pneumatic compression springs or compression springs of another type can alternatively be used. The mode of operation of the present invention is not linked to a specific type of compression spring, but rather the person skilled in the art can select and adapt them according to the requirements of the moment. The spring counterbearings, for example of mechanical springs, can be replaced, for example, by active surfaces of a piston of the respective pneumatic spring that can be subjected to the pressure of a pneumatic spring.

Claims (15)

1. Deep drawing tool (100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300) for deep drawing blanks (106, 1246) from material of sheet metal to produce raw shaped parts, with a drawing core (102, 1202) and a drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304 ), which can be moved linearly with respect to each other, and a fastener (110, 1248) as counter support for at least a part of the lower edge area of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) radially outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324) and at least one radially inner part (126, 226, 326, 426, 526, 626 , 726, 826, 926, 1026, 1126, 1226, 1326) which is movable with respect to the outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324 ), further comprising coupling means by which the outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324) and the inner part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, , 1304) are coupled during the deep drawing movement and are intended to cancel this coupling when a predetermined point of the deep drawing movement is reached; the coupling means comprising means for exerting a retaining force on the interior part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the drawing bell ( 104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) to retain it in a fixed position with respect to the exterior part (124, 224, 324, 424, 524 , 624, 724, 824, 924, 1024, 1124, 1224, 1324); characterized by The deep drawing tool comprises means for canceling or reducing the retention force in the interior part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the bell deep drawing (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304). 2. Deep drawing tool according to claim 1, characterized by drive means for a deep drawing movement in which the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004 , 1104, 1204, 1304) and the drawing core (102, 1202) move towards each other and are inserted into each other. 3. Deep drawing tool according to claim 1 or 2, characterized in that the coupling means comprise means for fitting the external part (124, 224, 324, 424, 524, 624, 724, 824) , 924, 1024, 1124, 1224, 1324) and the inner part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) with each other. 4. Deep drawing tool according to any one of claims 1 to 3, characterized in that the means for exerting a retention force comprise at least one spring (250, 350, 450, 550, 650, 750, 1150, 1250) by which the inner part (126, 226, 326, 426, 526, 626, 726, 1126, 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 1104, 1204 , 1304) is pressed to a fixed position with respect to the outer part (124, 224, 324, 424, 524, 624, 724, 1124, 1224, 1324). 5. Deep drawing tool according to claim 4, characterized in that the spring is a mechanical spring (250, 350, 450, 550, 650, 1150, 1250) or a pneumatic spring (750, 1372, 1374). 6. Deep drawing tool according to any one of claims 4 or 5, characterized in that the spring is a compression spring (250, 1150, 1250, 1372) that is prestressed between the inner part (226, 1126, 1226) of the drawing bell (204, 1104, 1304) and a counter support (254, 1154, 1254, 1370) and because the means for canceling or reducing the retention force comprise a drive to move the counter support (254, 1154, 1254, 1370) in one direction to relax the compression spring (250, 1150, 1250, 1372). 7. Deep drawing tool according to any one of claims 4 or 5, characterized in that the spring is a compression spring (350, 450, 550, 650, 750, 850, 1256, 1374) that is pretensioned between the outer part of the drawing bell (304, 404, 504, 604, 704, 804, 1204, 1304) and a counter support (354, 454, 554, 654, 752, 852, 1254, 1370), through which the pressure of the spring can be transmitted to the inner part (326, 426, 526, 626, 726, 826, 1226, 1326) of the drawing bell (304, 404, 504, 604, 704, 804, 1204, 1304). 8. Deep drawing tool according to claim 7, characterized in that the means for canceling or reducing the retention force comprise a drive for moving the counter support (354, 454, 554, 654, 752, 852, 1254, 1370) in a direction to tension the compression spring (350, 450, 550, 650, 750, 850, 1256, 1374). 9. Deep drawing tool according to claim 7 or 8, characterized in that the means for canceling or reducing the retention force comprise a stop (460, 560, 660) that is arranged to be received by the counter support (454, 554, 654) during the deep drawing movement and upon contact of which the counter support (454, 554, 654) is pressed in one direction to tension or relax the compression spring (450, 550, 650). 10. Deep drawing tool according to any one of claims 4 to 9, characterized in that the spring comprises a pneumatic spring cushion (750, 850, 1372, 1374) with a first pressure chamber (758, 858, 1372) and means for transmitting the pneumatic pressure in the first pressure chamber to the interior part (726, 826, 1326) of the drawing bell (704, 804, 1304), comprising means for canceling or reducing the retention force. to control the pneumatic pressure in the first pressure chamber. 11. Deep drawing tool according to claim 10, characterized in that the means for controlling the pneumatic pressure in the first pressure chamber (758, 858, 1372) comprise a ventilation device and/or a piston (1370) that delimits the first pressure chamber (758, 858, 1372) and is movably arranged to modify the volume of the first pressure chamber (758, 858, 1372). 12. Deep drawing tool according to any one of claims 1 to 11, characterized in that the coupling means comprise a driving element (950) for the interior part of the drawing bell (904), which is attached to the part. exterior (924) of the drawing bell (904) by magnetic force in a magnetic support with switchable polarity, such that in a first switching position it occupies a first axial position and in a second switching position it occupies a second axial position which is linearly displaced with respect to the first axial position; or because the coupling means comprise a driving element (1050) for the interior part (1026) of the drawing bell (1004) which is arranged on the exterior part (1024) of the drawing bell (1004) in such a way radially displaceable and is held until the predetermined point of the deep drawing movement is reached by a cam track (1058) that is arranged stationary with respect to the drawing bell (1004) or that moves together with the drawing core in a position of engagement with the inner part (1026) of the drawing bell (1004) and when this predetermined point is reached it is released for a radial displacement, by which the inner part (1026) of the drawing bell (1004) is released from the socket. 13. Deep drawing tool according to any one of claims 1 to 12, characterized in that the drawing bell (1104, 1204) comprises a first radially internal part (1126, 1226) and a second radially internal part (1128, 1228) , whose first inner part (1126, 1226) is arranged between the outer part (1124, 1224) and the second inner part (1128, 1228), and by other coupling means by which the first inner part (1126, 1226) and the second inner part (1128, 1228) are coupled during the deep drawing movement and are provided to cancel this coupling when another predetermined point of the deep drawing movement is reached. 14. Procedure for deep drawing blanks from sheet material to give shaped blanks by using a deep drawing tool according to one of the preceding claims, characterized by the following steps: a) provide the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) and the drawing core in a stroke position in which it is a free space between the lower side of the drawing bell and the drawing core, leaving the lower sides of the radially outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324) and the radially inner part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) essentially flush with each other; b) positioning a blank in the free space; c) carrying out a deep drawing movement by which the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) and the drawing core are move towards each other in such a way that the edge of the blank projecting radially above the drawing core is trapped between the underside of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) and the fastener and is drawn above the drawing core; d) continue the deep drawing movement until the outer edge of the deep drawn edge of the blank is trapped between the lower side of the inner part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304) and the fastener; e) cancel the coupling between the outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324) and the inner part (126, 226, 326, 426, 526 , 626, 726, 826, 926, 1026, 1126, 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304), the inner part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126, 1226, 1326) being freely mobile with respect to the outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324) or actuated to move with respect to the outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124 , 1224, 1324); f) further continue the deep drawing movement with contact between the fastener and the outer part (124, 224, 324, 424, 524, 624, 724, 824, 924, 1024, 1124, 1224, 1324) of the bell drawing (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304). 15. Method according to claim 14, characterized in that during step f) the drawing core is further inserted into the interior part (126, 226, 326, 426, 526, 626, 726, 826, 926, 1026, 1126 , 1226, 1326) of the drawing bell (104, 204, 304, 404, 504, 604, 704, 804, 904, 1004, 1104, 1204, 1304), in such a way that the blank continues to be subjected to deep drawing and the residual lip continues to reduce in size, or the deep drawn edge of the blank is completely stretched.