EP2364792B1 - Forming device - Google Patents

Description

The invention relates to a forming device for cup-shaped hollow body with a machine frame, a drive device, a workpiece turntable for receiving workpiece holders, which are designed to define hollow bodies, and with a tool carrier for receiving processing tools, wherein the workpiece rotary table and tool carrier are opposite and about an axis of rotation to each other rotatable and along the axis of rotation are mutually linearly adjustable, wherein the drive means for providing a rotary step movement and a cyclic linear movement between the workpiece rotary table and tool carrier is formed to allow a deformation of the hollow body by means of the processing tools in several successive processing steps and wherein the workpiece holder has a recess for receiving a Has hollow body and a recess partially limiting wall portion a narrowing of the cross-section de R recess formed, adjustable geometry to allow a determination of the hollow body on the workpiece holder.

From the EP 0 275 369 A2 a forming machine is known with the cup-shaped hollow body made of metal, in particular aluminum, from a substantially cylindrical sleeve-shaped initial state partially formed, in particular locally retracted, can be, for example, in the area the opening a cap or a spray valve sealingly put on. The known forming machine has a machine frame, on which a support tube is formed. On an outer surface of the support tube, a workpiece rotary table is rotatably mounted. In a recess bounded by the support tube, a linearly displaceable guide tube is accommodated, at the end region of which the tool rotary table is mounted. In the machine frame, a drive device is received, which is designed to generate an intermittent rotary motion of the workpiece rotary table and to produce an oscillating linear movement of the guide tube and the associated rotary tool table. As a result of the linear movement, the tools provided on the tool rotary table, in particular forming tools, can be brought into engagement with the hollow bodies held on the workpiece rotary table in order to process them locally, in particular to plastically deform them. Due to the intermittent rotational movement of the workpiece rotary table, the hollow bodies can be brought into serial contact with the tools mounted on the tool carrier table in order to achieve a step-by-step transformation of the hollow bodies from an initial geometry to a target geometry. Before carrying out the machining, the hollow bodies are fixed by means of workpiece holders mounted on the workpiece rotary table and released again after the processing has been carried out. For this purpose, the workpiece holder has a pneumatically actuable piston, which acts in the axial direction on a circumferential, flexible ring and this can displace at least partially in the radial direction inwardly so as to clamp the hollow body on an outer surface and thus set on the workpiece holder.

The object of the invention is to provide a forming device which allows a reliable and optionally during the forming process for the hollow body at least temporarily releasable fixation of the hollow body on the workpiece holder.

This object is achieved for a forming device of the type mentioned with the features of claim 1. It is provided that the wall portion is formed with the adjustable geometry of a flexible membrane, which limits a formed in the workpiece holder fluid channel regions. The flexible membrane is acted upon directly by the fluid pressure prevailing in the fluid channel, so that a conversion of the amount of energy provided for clamping the hollow body, for example in the form of kinetic energy in the context of an actuating movement, is implemented with a favorable efficiency in an amount of energy serving to clamp the hollow body. As a result, the amount of energy required to fix the hollow body can be kept low. As a result, adjusting means for providing the fluid pressure in the fluid channel can be dimensioned small and inexpensive. In addition, geometric deviations in the outer contour of the hollow body can advantageously be compensated by the flexible membrane, which preferably has a significantly higher elasticity than the hollow body, which is usually thin-walled. Local stress peaks, as they can occur by the compression of the flexible ring, as it is known from the prior art, account for at least almost completely, since prevail in the fluid channel everywhere the same pressure conditions. Thus, a local overloading of the hollow body is avoided during the clamping process. In addition, with appropriate design of the flexible membrane, for clamping provided fluid pressure and the workpiece holder a slight residual mobility of the hollow body relative to the workpiece holder are allowed. This residual mobility ensures that the reaction forces which occur, for example, in the case of forming processes on the hollow body and can be diverted into the workpiece holder do not lead to local stress peaks. Rather, the hollow body can escape at least slightly when high reaction forces occur in order to avoid voltage peaks in the hollow body.

It is expedient if in the fluid channel, a, preferably linearly movably mounted, fluid displacement means is arranged, which is designed to influence a fluid pressure in the fluid channel in order to effect a change in shape of the flexible membrane can. The fluid displacement device is used, in particular from the outside on the workpiece holder introduced adjustment energy, preferably in the form of a linear and / or rotary actuating movement, to effect a pressure increase of the fluid received in the fluid channel, in particular a hydraulic fluid. The point energy can also be provided in the form of a magnetic field and / or electrical energy from the outside or in a storage device, such as an electric accumulator, held in the workpiece holder to a corresponding fluid displacement means, such as a magnetically or electromagnetically driven piston, a magnetic and / or electrical operable fluid pump or a piezoelectric pump to operate.

The fluid displacement device preferably has a rigidly displaceably mounted, rigid working piston or a flexible working diaphragm which is sealingly clamped on the edge, in particular designed as a rolling diaphragm. A linearly displaceably mounted working piston is preferred then used when high clamping forces to fix the hollow body and thus a high pressure in the fluid channel are required. A flexible working membrane enables a particularly cost-effective provision of a fluid displacement device. Preferably, the flexible working diaphragm is a linearly movably guided, arranged outside the fluid-filled fluid channel displacement body, for example, plastic assigned. The displacement body ensures that the working diaphragm can not escape in an undesired manner when pressure is applied to the fluid in the fluid channel, which would jeopardize the pressure build-up on the fluid. In addition, the displacement body can be shaped such that the working diaphragm is always guided during the build-up of the pressure in the fluid channel without kinks and / or local stress peaks in order to avoid premature wear of the working diaphragm. This is especially true when the working diaphragm is designed as a rolling diaphragm, which allows a particularly compact design of the working diaphragm and slide past each other in the annularly formed and interconnected membrane areas during pressure build-up or pressure reduction.

In a further development of the invention, it is provided that the fluid displacement device is associated with a, preferably a spring means comprehensive, biasing means, which is adapted to adjust the fluid displacement means in a preferred position, preferably in a pressure position. The biasing means ensures that the workpiece holder without an external adjusting movement or an external control signal is in a defined preferred position with regard to the clamping of the hollow body to be accommodated. The defined preferred position may be, for example, a position in which the fluid channel absorbed fluid is depressurized, in particular, has no pressure difference from a surrounding atmosphere, and thus the flexible membrane is not or only slightly deformed and thus releases a maximum free cross-section in the recess of the workpiece holder. It is particularly advantageous if the preferred position corresponds to a clamping position in which a hollow body is fixed in the workpiece holder. Since a considerable part of the processing steps in the forming device requires a fixation of the hollow body on the workpiece holder, it is advantageous if during this processing steps no provision of energy is necessary to ensure the determination of the hollow body. Provision of energy, in particular in the form of an adjusting movement introduced from outside onto the workpiece holder, is then necessary in the event that the hollow body is to be partially or completely freed from the workpiece holder. This is achieved in that the biasing means, which may be, for example, a spring means, in particular a compression spring or a disc spring assembly, are arranged on the workpiece holder in such a way that they urge the fluid displacement means into a position in which one for fixing the hollow body necessary pressure in the fluid channel prevails and the flexible membrane is deflected such that it can exert a sufficient, preferably radially inwardly directed clamping force on the hollow body. To release the hollow body, it is accordingly required that an amount of energy is introduced to the biasing means, which is sufficient to bring the biasing means from a substantially relaxed preferred position to a cocked operating position. In this case, the pressurization in the fluid channel is then at least partially, in particular completely, repealed and the hollow body is released.

Preferably, the fluid displacement means comprises a pivotally mounted actuating lever, which is designed for coupling a working ram operatively connected to the working piston or the working diaphragm with the biasing means and / or for initiating an external adjusting movement on the working ram. The operating lever permits a compact arrangement of the biasing means on the workpiece holder, since it is not necessary to arrange the biasing means in the immediate vicinity of the fluid displacement device. Additionally or alternatively, the actuating lever may be provided to initiate an externally applied to the workpiece holder, in particular serving to release the hollow body actuating movement, on the fluid displacement means and preferably at the same time on the biasing means. The fluid displacement device comprises a preferably extending over an outer contour of the workpiece holder, linearly movably mounted working ram, which is designed for power transmission between the actuating lever and the working piston or the working diaphragm. Among other things, the work ram has the task of converting the pivoting movement of the pivotably mounted actuating lever into a linear movement for the working piston or the working diaphragm.

In one embodiment of the forming device is provided that the flexible membrane is annular. As a result, the hollow body can be stretched over an annular region of its outer surface which is rotationally symmetrical with respect to its longitudinal axis, so that a reliable force transmission between hollow body, membrane and workpiece holder is always ensured, irrespective of possibly asymmetrically acting on the hollow body machining forces. Preferably, the membrane is annular, since the processed Hollow body, at least in the clamping area, in which the membrane comes into contact with the outer or surface of the hollow body, are rotationally symmetrical. In one embodiment of the invention, the membrane is torus-shaped and has at least one, preferably in the radial direction outwardly projecting connecting piece for a communicating fluidic connection with the formed in the workpiece holder fluid channel.

It is expedient if the flexible membrane in a cross-sectional plane which comprises a longitudinal axis of the recess has a radially outwardly open, U-shaped cross-section. This allows a cost-effective production of the membrane can be achieved. For example, the membrane can be formed as a plastic injection molded part.

Preferably, the flexible membrane is designed such that an area of the inner surface region of the flexible membrane performs a movement upon pressurization of the fluid channel, which is directed radially inwardly and directed parallel to the longitudinal axis of the recess, in particular in one of the orifice, Movement component has. As a result, in addition to the determination of the hollow body, which is effected by the radially inwardly directed movement of the membrane, and an axial displacement of the hollow body during the clamping operation allows, without the need for additional devices would be required. By the axial displacement of the hollow body, by which it is urged preferably in the direction of the bottom of the recess of the workpiece holder, it can be achieved that the hollow body comes into abutment with a provided in the bottom region of the recess contact surface. As a result, a correct system and alignment of the hollow body to the workpiece holder or favored with respect to the workpiece holder, which has an advantageous effect on the processing quality for the forming operations to be carried out on the hollow body.

In a further embodiment of the invention, it is provided that the flexible membrane is designed such that the two mutually perpendicularly aligned movement components are at least almost equal.

Preferably, at least one leg of the U-shaped cross-section of the flexible membrane includes an acute angle, preferably an angle less than 80 degrees, more preferably an angle less than 70 degrees, in particular an angle less than 60 degrees, with the longitudinal axis of the recess. By choosing the angle, the movement component for the flexible membrane can be determined when carrying out the clamping operation. The smaller the included angle, the greater the component of motion along the longitudinal axis of the recess.

It is advantageous if both legs of the U-shaped cross section of the flexible membrane are aligned at least almost parallel to one another. This ensures that the flexible membrane rests as uniformly as possible and flat on the outer surface of the hollow body.

In a further development of the invention, it is provided that at least one leg of the U-shaped cross section of the flexible membrane in a radially outer peripheral region has a circumferential bead, which is designed for a sealing fixation in the workpiece holder. Due to the at least one peripheral bead, the radially outer circumferential region of the membrane can be received in a form-fitting manner and optionally also in a force-fitting manner on the workpiece holder become. Due to the positive reception advantageous power transmission between the membrane and workpiece holder is ensured in a simple manner. The non-positive fixing of the membrane brings a compression of the elastic, preferably rubber-elastic, membrane material with it, whereby the seal between the membrane and the formed in the workpiece holder fluid channel is favored.

Preferably, a cone ring is arranged between the flexible membrane and an opening opening of the Aushehmung, the conical inner surface of the recess is partially limited and tapers with increasing distance from the mouth opening. The cone ring has the task of achieving a centering of the hollow body when inserting the hollow body into the recess of the workpiece holder. In addition, the conical ring serves to protect the flexible membrane, which is indeed at least almost completely relaxed during the insertion of the hollow body and thus releases a maximum cross-section of the recess, but could be damaged by faulty hollow body and / or by an oblique insertion of the hollow body. Preferably, a minimum inner diameter of the cone ring is selected slightly larger than a maximum diameter of the membrane in the relaxed state, so that contact with the membrane is always avoided when inserting the hollow body.

It is expedient if the flexible membrane is designed for a contact contact with the hollow body in an annular region which has a width of less than 20 mm, preferably less than 15 mm, more preferably less than 10 mm, in particular less than 5 mm, and that of a bottom plane the hollow body, which is determined by the recess, a distance of less than 20mm, preferably less than 15mm, more preferably less than 10mm, especially less than 5mm, occupies. With a small width of the annular contact area and a small distance of the contact area from the bottom plane of the hollow body received in the workpiece holder ensures that the hollow body processed almost over its entire length and close to the ground plane, in particular can be formed. Preferably, a Berührkontakt is provided in a region of the hollow body, which is spaced less than 10mm from the bottom portion and in which the annular contact region has a width of less than 10mm. More preferably, a lower range limit of the touch region is spaced less than 5mm from the ground plane, and an upper range limit of the touch region is less than 9mm, preferably less than 8mm, from the ground plane. An advantageous width of the annular contact area is thus in particular 5 mm or less.

In a further embodiment of the invention it is provided that the workpiece rotary table at a locking position, a first adjusting means for initiating a locking movement to the respective workpiece holder and / or at an unlocking second actuating means for initiating a release movement and at a processing position, a third adjusting means for initiating a positioning movement at least partially unlocking and subsequent locking of the hollow body during a cycle of the cyclic linear movement are assigned to the respective workpiece holder. The first adjusting means allows a locking of the hollow body on the workpiece holder and is arranged in particular at a loading position for the workpiece rotary table. At the loading position, the hollow bodies of a preceding conveyor, such as a conveyor belt, by means of an intermediate conveyor, for example a vacuum-loaded charging star, fed to the workpiece holder. The second adjusting means is arranged at an unlocking position at which the workpiece holder releases the processed hollow body for further transport through a subsequent conveying device, for example a conveyor belt. The third actuating means serves to at least partially release the hollow body during a cycle of the cyclic linear movement, in particular during a temporal fraction of the cyclical linear movement, and subsequently to lock it again. In the time window between at least partial unlocking and re-locking, the hollow body can be moved, for example, in particular aligned with respect to the workpiece holder.

Figur 1

eine schematische Seitenansicht einer Umformeinrichtung,

Figur 2

eine teilweise geschnittene Vorderansicht der Umformeinrichtung gemäß der Figur 1,

Figur 3

eine perspektivische Darstellung eines Werkstückhalters,

Figur 4

eine teilweise geschnittene Vorderansicht des Werkstückhalters,

Figur 5

eine Schnittdarstellung des Werkstückhalters und

Figur 6

ein zeitliches Ablaufschema für die Durchführung eines Bearbeitungsverfahrens unter Einsatz der Umformeinrichtung.

An advantageous embodiment of the invention is shown in the drawing. Showing:

FIG. 1

a schematic side view of a forming device,

FIG. 2

a partially sectioned front view of the forming device according to the FIG. 1 .

FIG. 3

a perspective view of a workpiece holder,

FIG. 4

a partially sectioned front view of the workpiece holder,

FIG. 5

a sectional view of the workpiece holder and

FIG. 6

a temporal flow chart for the implementation of a processing method using the forming device.

One in the FIG. 1 Forming device 1 shown is designed for a processing of hollow bodies, in particular aluminum cans, in a step-by-step forming process. The forming device 1 comprises a machine frame 2 on which, by way of example, a workpiece rotary table 3 is rotatably mounted and a tool carrier 4 is mounted in a linearly movable manner, as indicated by the corresponding arrows in FIG FIG. 1 is indicated.

The workpiece rotary table 3 is by means of a in the FIG. 1 Drive device not shown in a stepwise rotational movement, which is also referred to as a rotary step movement, about an axis of rotation 5 movable. The drive device and the workpiece rotary table 3 are preferably matched to one another in such a way that the rotary step movement always takes place with the same step width, in particular with the same angle about the axis of rotation 5. On the workpiece rotary table 3, a plurality of workpiece holders 6 are arranged, preferably in the same angular pitch about the axis of rotation 5, which are adapted to receive hollow bodies 7.

The in the FIG. 1 not shown, received in the machine frame 2 drive device is also designed to provide a cyclic linear movement of the tool carrier 4. The tool carrier 4 is mounted linearly movable on a support tube 8 and can perform an oscillating lifting movement relative to the workpiece rotary table 3. On the tool carrier 4 a plurality of tool holder 9 are arranged, which are arranged at the same angular pitch about the axis of rotation 5 as the workpiece holder 6 on the workpiece rotary table 3 and which are provided for receiving machining tools 10, in particular forming tools or cutting tools such as milling cutters. With the help of the processing tools 10 can within the cyclic linear movement of the tool carrier Umformoperationen or other machining operations are performed on the received in the workpiece holders 6 hollow bodies.

In each resulting after performing a rotary step movement working position of the workpiece rotary table 3, the workpiece holder 6 are arranged opposite to the tool holders 9 and can make the desired processing of the hollow body in the context of cyclic linear movement.

From the schematic representation of FIG. 2 the arrangement of the workpiece holder 6 in a constant angular pitch around the perpendicular to the plane of rotation axis 5 can be seen. The direction of the rotary step movement for the workpiece rotary table is given by way of example counterclockwise. Each of the workpiece holders 6 assumes a fixed working position in a time interval between two rotary step movements, in which an interaction with the machining tools 10, which are received on the invisible tool carrier 4 and are likewise not shown, is provided.

In the FIG. 2 is the support tube 8, on which the tool carrier is guided linearly movable, visible in a sectional view. In the support tube 8, a non-illustrated coupling carriage is guided along a perpendicular to the plane of the FIG. 2 aligned movement axis can be moved linearly. The coupling carriage is coupled to a connecting rod 11. The connecting rod 11 is coupled to a double eccentric assembly 12 which can be rotated by a drive means 15 about an axis of rotation 13 to produce a combined rotational and translational motion from a pure rotational movement which is transmitted to the connecting rod 11. The connecting rod 11 moves the coupling carriage in a cyclic linear movement, which is transmitted to the tool carrier 4.

Each of the workpiece holder 6 comprises an integrated clamping device 17, which is adapted to narrow a, for example, cylindrically shaped recess 16 in the workpiece holder 6 at least partially in the radial direction and thus apply the clamping force required for clamping the hollow body 7.

To control the tensioning device 17, each of the workpiece holders 6 is assigned, by way of example, an actuating lever 18, which is mounted pivotably on the workpiece holder 6 by means of a pivot bearing 26 and which is provided for actuating a control pin 19 provided by way of example. The control pin 19 is associated with the tensioning device 17 and can act, for example, on a fluid piston, not shown, of the tensioning device 17, which is provided, for example, for pressurizing a fluid contained in the tensioning device 17, in particular a hydraulic fluid. By way of example, provision may be made for the tensioning device 17 to comprise an annular, elastic membrane arranged circumferentially in the recess 16, which will be described in more detail below. This membrane may be configured such that it bulges inward in the radial direction upon pressurization of the fluid in the tensioning device 17 and thereby causes the desired narrowing of the cross section of the recess 16 in order to tension the hollow body 7.

The actuating lever 18 has, by way of example, on a surface facing away from the workpiece holder 6, a cam extension 20 which is provided for engagement with control elements described in more detail below. Between one the tax pin remote from the end portion of the actuating lever 18 and the workpiece holder 6, a spring device 21 is arranged, which may be formed, for example, as a compression spring, in particular as a coil spring or cup spring stack. The spring device 21 exerts, for example, a compressive force on the associated end region of the actuating lever 18. By way of example, the pressure force is dimensioned such that the tensioning device 17 is brought into a tensioned preferred position without external influences. This ensures that, without an external influence on the workpiece holder 6, in particular on the actuating lever 18, the clamping device 17 reliably fixes the hollow body 7 in the workpiece holder 6.

In order to unlock the hollow body 7 from the workpiece holder 6, an actuating movement directed inwardly at least almost in the radial direction is introduced on the actuating lever 18 by way of example. This adjusting movement can be introduced in a first embodiment of an actuating means as a pure linear movement of the actuating lever 18. For this purpose, for example, a fluidically or electrically operated linear actuator, in particular a fluid cylinder or an electric linear direct drive, can be used. By way of example, in the embodiment of the Fig. 2 the first adjusting means 22 and the second adjusting means 23 each formed as a linear actuator. Between the second adjusting means 23, which are associated with an unloading position 24 of the workpiece rotary table 3 and the first adjusting means 22, which are associated with a loading position 25 of the workpiece rotary table 3, a control rail 28 is arranged. The control rail 28 is formed so as to act on the cam extension 20 of the operating lever 18 and the operating lever 18 along a circular path of movement of the workpiece holder 6 between the second adjusting means 23 and the first adjusting means 22 forces in an operating position in which the clamping devices 17 are at least almost completely relaxed. In the present case, the clamping device 17 is relaxed at the unloading position 24 by means of the second adjusting means 23 by controlling the actuating lever 18, whereby a removal or expulsion of the hollow body 7 from the workpiece holder 6 is made possible. The workpiece holder 6 which arrives at the loading position 25 in the course of the rotary step movements with a relaxed tensioning device 17 is initially held by the first adjusting means 22 in the illustrated relaxation position. Even before the initiation of a further rotary step movement on the workpiece rotary table 3, a hollow body 7 is first inserted into the workpiece holder 6. Subsequently, the first adjusting means 22 releases the actuating lever 18, so that it can return to its preferred position according to the bias of the spring means 21, in which the clamping device 17 is stretched and the hollow body 7 is fixed in the workpiece holder 6.

At the first processing position 29, which is offset from the loading position 25 in an angular step of the rotary step movement, takes place by way of example an at least partially unlocking and then a renewed locking of the hollow body 7 in the workpiece holder 6. For this purpose, an adjusting module 31 adjacent to the workpiece rotary table 3 is arranged is fixedly connected to the machine frame 2. The control module 31, which in the FIGS. 3 to 5 3, by way of example, comprises three further adjusting means 32, 33, 34 which are each designed to initiate at least proportionally linear positioning movements on the actuating levers 18 of the respectively temporarily opposing workpiece holders 6. Each of the adjusting means 32, 33, 34 has a rotatably mounted cam 35 which is rotatably mounted on the Positioning module 31 is mounted and can be offset from drive means not shown in a rotational movement.

The in the FIGS. 3 to 5 illustrated workpiece holder 6 forms an independent assembly, which can be exactly determined locally on the workpiece rotary table 3 by means not shown mounting means, in particular screwing, and positioning, in particular dowel pins.

The workpiece holder 6 comprises a basic body 36, preferably made of metal, on which the actuating lever 18, the spring device 21 and a fluid displacement device 38 described in more detail below are arranged. The actuating lever 18 is pivotally mounted on the workpiece holder 6 by means of the pivot bearing 26, which comprises a hinge pin 44 rotatably mounted in the base body 36. The operating lever 18 includes a first lever portion 45 and a second lever portion 46, each extending from the pivot bearing 26 in opposite directions. The first lever portion 45 is located on the end of the control pin 19 which is associated with the fluid displacement means 38. The second lever portion 46 is fork-shaped at the end and carries between the fork legs a rotatably mounted drag roller 43rd

With a base body 36 arranged opposite the underside of the second lever portion rests on a guide pin 48 of the spring means 21. The guide pin 48 is accommodated in a helical spring 47 and serves to transmit the spring force of the helical spring 47, which is embodied by way of example as a compression spring, onto the actuating lever 18.

In the recess 16 of the workpiece holder 6, a cone ring 37 is arranged, which limits the recess 16 partially and the region tapers conically. Below an end region of the cone ring, an annular circumferential, flexible membrane 42 is arranged, which defines a shape described below in detail, formed in the base body 36 fluid channel 40 shape variable and is provided for a temporary and reversible narrowing of the free cross section of the recess 16 to a hollow body. 7 clamp.

Like from the FIG. 4 As can be seen, the fluid displacement device 38 comprises a cap mounted on the base body 36, screwed by way of example. The cap 49 serves as a linear guide for the control pin 19, which is coupled to a guide body 53 arranged below the cap 49. For the linear guide of the control pin 19, which passes through the cap 49, a fixed in the cap 49 slide bushing 56 is provided.

The cap 49 also serves to define the rotationally symmetrical rolling diaphragm 50, which is held sealingly on a radially outer edge region between the cap 49 and the base body 36. The guide body 53 is connected by means of a retaining bolt 57, which is screwed by way of example in the control pin 19, with the control pin 19, that the rolling diaphragm 50 seals the fluid channel 40 and the fluid received therein in a radially inner region relative to the surrounding atomic sphere.

The guide body 53 serves to support the rolling diaphragm 50 in the case of a linear movement of the control pin 19 in the direction of the working space 59 formed in the main body 36, and thus to ensure that the rolling diaphragm 50 does so in the fluid channel 40, in particular in the working space 59, located, not shown fluid under pressure sets.

At an end region opposite the control pin 19, the retaining bolt 56 has an annular guide collar 58, in which a first end region of a return spring 54 is accommodated. The second end region of the return spring 54 engages around a guide pin 55, which is screwed by way of example into the base body 36. The object of the return spring 54 is, without the presence of external influences on the fluid displacement device 38, the guide pin 19, the rolling diaphragm 50, the retaining pin 57 and the guide body 53 in the in FIG. 4 shown position in which there is at least almost no pressurization of the fluid and in which no clamping forces are exerted on a hollow body 7.

In the present embodiment, the workpiece holder 6, the spring means 21 is formed such that a spring force is always exerted on the second lever portion 46, whereby a pressure force on the control pin 19 of the fluid displacement means 38 is applied. By this pressure force attached to the control pin 19 rolling diaphragm 50 by means of the guide body 53 from the in FIG. 4 shown position moves in the direction of the working space 59, whereby a pressurization of the fluid occurs. Due to this pressurization, the in FIG. 5 Membrane 42, which is shown in greater detail, is acted upon by the fluid pressure on an outer surface and thereby stretched. The membrane 42 performs in their expansion a combined radial and axial movement. In this case, the radial component of the movement in the radial direction is directed inwards and can cause the installation of the membrane 42 on an outer surface 60 of the hollow body 7. The axial component of the movement is parallel to a longitudinal axis 39 of the hollow body 7 and the recess 16 is aligned and acts from the mouth 41 of the recess 16 in the direction of a received in the recess 16 Bodenformstößels 61. The direction of expansion of the diaphragm 42 is indicated by the directional arrows 51. As a result, the hollow body 7 is acted upon not only in the radial direction with a clamping force, but is also drawn in the axial direction in the workpiece holder 6 at least by a certain amount.

The bottom forming ram 61 is provided to effect the concave impression in the bottom of the hollow body 7 upon application of a pressure force directed from the opening of the hollow body 7 in the direction of the bottom forming ram 61. For this purpose, the bottom mold tappet 61 is provided on a surface facing the hollow body 7 with a convex geometry, which is impressed into the hollow body 7 during the forming process. In addition, the bottom mold ram 61 can be used to eject the hollow body 7 from the workpiece holder 6. For this purpose, the Bodenformstößel 61 is moved relative to the base body 36 in the direction of the mouth 41 of the recess 16. The bottom forming ram 61, together with a support ring 63 described in more detail below, determines the bottom plane 79 of the hollow body 7, which can also be referred to as the contact surface of the hollow body 7.

In order to ensure a reliable contact of the hollow body 7 in the workpiece holder 6, a support ring 63 is arranged circularly around the bottom mold tappet 61, which in turn has a circular peripheral, concave recess in which the edge region of the hollow body 7 can be received and supported. On the support ring 63 is a pressure ring 62, which is conically formed on a surface 64 remote from the support ring 63. Between a conical outer surface 65 of the cone ring 37 and a circumferential retaining ring 66, which extends obliquely inwards in the direction of the bottom mold tappet 61 and exemplarily runs like a blade, formed with a U-shaped cross-section flexible membrane 42 is received. The membrane 42 defines in the radial direction inwardly a chamber associated with the fluid channel 40, which is bounded outwardly from the retaining ring 66 and in the FIG. 5 is not visible due to the lack of pressurization of the fluid. When the chamber is pressurized, the membrane 42 lifts at least in places from the surface of the retaining ring 66 and expands in the radial direction inwardly and in the axial direction, as shown in FIG FIG. 5 down, out. The volume of the chamber corresponds to the volume of fluid that is displaced by the fluid displacement device 38 upon initiation of a linear adjusting movement on the control pin 19 in the working space 59.

The retaining ring 66 is formed on a substantially cylindrically shaped channel ring 67, which is received in a cylindrical portion of the recess 16. The channel ring 67 has on its outer circumference a plurality of circumferential grooves 68, 69, 70. In the grooves 68 and 70 respectively sealing rings 71 are added, which serve to seal the third groove 69 serving as part of the fluid channel 40 relative to the atmosphere. Through the circumferential groove 69 are introduced in the channel ring 66 and opening out on the outer surface of the diaphragm 42 oblique holes in communicating connection with the working space 59th

The membrane 42 formed with a U-shaped cross-section has a first U-leg 73, a second U-leg 74 and a membrane ring 75 connecting the two legs 73 and 74. Each of the two legs 73, 74 is each end, radially outwardly provided with a circumferential bead, which is provided in each case for a positive reception between the outer surface 65 of the cone ring 37 and the retaining ring 66 and between the retaining ring 66 and the conical surface 64 of the pressure ring 62. The two legs 73, 74 are aligned almost parallel to each other, the diaphragm ring 75 is formed in the relaxed position of the membrane 42 is almost cylindrical, with its rotational symmetry axis coincides with the longitudinal axis 39.

Preferably, the retaining ring 66 in areas near the channel ring 67 each have circumferential, groove-like recesses 77, 78, which serve for a positive reception of the circumferential beads 76. The retaining ring 66, the conical ring 37 and the pressure ring 62 and the beads 76 of the membrane 42 are matched to one another such that the membrane 42 is wedged both edge positive and non-positive, whereby a secure and tight fixing of the membrane 42 is ensured. The membrane 42 thus at least partially seals off the fluid channel 40 from the atmosphere and thereby forms the wall section of the recess 16 that is adjustable in its geometry.

In the illustrated embodiment of the workpiece holder 6, a distance denoted by 11 between the bottom plane 79 and a lower range limit of a contact area between the membrane 42 and the hollow body 7 is spaced less than 5mm from the ground plane. A distance between the lower range limit of the touch area and the upper limit of the range is also less than 5 mm. Thus, the hollow body 7 is stretched measured from the ground plane 79 in an annular region, is about 4 mm wide and about 4 mm from the ground plane 79 is spaced.

Preferably, the retaining ring 66, the cone ring 37 and the pressure ring 62 together with the membrane 42 received thereon form a separate assembly which can be mounted independently of the base body 36 and tested for leaks. In a later assembly step, this assembly is only to be provided with the sealing rings 71 and inserted into the recess 16 of the workpiece holder 6. Due to the circumferential groove 69, no rotational alignment of the assembly relative to the base body 36 must be made. Rather, the communicating connection between the fluid channel 40 and the oblique bores 72 results solely from the insertion of the assembly into the recess 16.

That in the FIG. 6 The flow chart shown is an example of the processes taking place during the processing of the hollow body 7. The time t [s] is plotted on the abscissa of the flow chart, the path s [m] is plotted on the ordinate. The cyclic linear movement can be represented for example as a sinusoidal linear oscillation of the tool carrier 4 and is denoted by the letter L. The cyclic linear motion is repeated within a time interval designated to.

The rotational step movement, which is denoted by the letter D, can be represented by way of example as a sequence of sinusoidal halves, which are temporally spaced from each other. The rotational step movement takes place in each case within a time interval designated with t1. Preferably, the cyclic linear movement and the rotational step movement are coordinated such that the workpiece rotary table 3 rests while the machining tools 10 are in engagement with the hollow bodies 7. The intervention period is designated t2.

Although the linear positioning movements S3, S4 and S5 of the third, fourth and fifth adjusting means 32, 33 and 34 are synchronized with each other with respect to the traction means constrained coupling with respect to the respective angular velocity, but have due to the different geometric configuration of the cam 35 different phase profiles , The adjusting movements S3 and S4 take place within the engagement period designated by t2, the adjusting movement S5 already starts before the intervention period t2 and ends only after expiration of the engagement period t2, wherein presently no overlapping of the adjusting movements S3, S4 and S5 with the rotational step movement are provided. This ensures that the hollow bodies 7 are reliably fixed in the workpiece holders 6 during the rotary step movement.

The phase curve S3 for the linear adjusting movement of the third adjusting means 32 is selected such that the clamping device 17 of the oppositely disposed workpiece holder 6 is brought from the fully locked preferred position to a fully unlocked unlocking position and then back to the fully locked preferred position. For example, the hollow body 7 can thus be pushed into the workpiece holder 6 after a bottom forming process, in which the contact of the hollow body bottom with a contact surface in the workpiece holder 6 is lost, and thus returned to surface contact with the workpiece holder 6.

The phase curve S4 for the linear adjusting movement of the fourth adjusting means 33 is selected such that the clamping device 17 of the oppositely disposed workpiece holder 6 from the fully locked preferred position over a short period of time, preferably less than 15 percent corresponds to the cycle time of the cyclic linear movement is brought into a partially unlocked unlocking position and then back to the fully locked preferred position. For example, the hollow body 7 can thereby be aligned correctly again relative to the workpiece holder 6 after a machining operation with machining forces acting asymmetrically on the hollow body 7.

The phase curve S5 for the linear actuating movement of the fifth actuating means 34 is selected such that the clamping device 17 of the oppositely disposed workpiece holder 6 from the fully locked preferred position over a longer period of time, which corresponds to nearly 25 percent of the cycle time of the cyclic linear motion, in a partially unlocked unlocking position and then returned to the fully locked preferred position. For example, the hollow body 7 can thus be rotated into a correct rotational position by means of a rotary tool mounted on the tool carrier 4 after a detection process in which the rotational position of the hollow body 7 has been determined about its longitudinal axis.

Claims (15)

1. Forming apparatus for cup-shaped hollow bodies (7), comprising a machine frame (2), a drive device (15), a workpiece rotary table (3) for the accommodation of workholders (6) designed for the location of hollow bodies (7), and a tool carrier (4) for the accommodation of machining tools (10), wherein the workpiece rotary table (3) and the tool carrier (4) are arranged opposite one another, rotatable relative to one another about an axis of rotation (5) and capable of linear displacement relative to one another along the axis of rotation (5), wherein the drive device (15) is designed for the provision of a rotary step movement and a cyclical linear movement between the workpiece rotary table (3) and the tool carrier (4) in order to allow the hollow bodies (7) to be formed by means of the machining tools (10) in several machining steps, and wherein the workholder (6) has a recess (16) for the accommodation of a hollow body (7) and a wall section (42) which partially bounds the recess (16) has an adjustable geometry designed for narrowing the cross-section of the recess (16) in order to locate the hollow body (7) on the workholder (6), characterised in that the wall section (42) having the adjustable geometry is represented by a flexible membrane which partially bounds a fluid passage (40) formed in the workholder (6).
2. Forming apparatus according to claim 1, characterised in that a fluid displacement device (38), which is preferably bearing-mounted for linear movement and which is designed for influencing a fluid pressure in the fluid passage (40) in order to effect a change in the shape of the flexible membrane (42), is provided in the fluid passage (40).
3. Forming apparatus according to claim 2, characterised in that the fluid displacement device (38) comprises a rigid operating piston bearing-mounted for linear displacement or a flexible operating membrane (50) which is clamped at the edges to form a seal and which is in particular designed as a rolling membrane.
4. Forming apparatus according to claim 2 or 3, characterised in that a preloading means (21), which preferably comprises a spring means and which is designed for setting the fluid displacement device (38) to a preferred position, preferably to a pressure position, is assigned to the fluid displacement device (38).
5. Forming apparatus according to claim 4, characterised in that the fluid displacement device (38) comprises a pivotably mounted operating lever (18), which is designed for coupling an operating plunger (19) operatively connected to the operating piston or to the operating membrane (50) to the preloading means (21) and/or for introducing an external actuating movement into the operating plunger (19).
6. Forming apparatus according to any of the preceding claims, characterised in that the flexible membrane (42) is annular.
7. Forming apparatus according to any of the preceding claims, characterised in that the flexible membrane (42) has in a cross-sectional plane which includes a longitudinal axis (39) of the recess (16) a U-shaped cross-section open towards the outside in the radial direction.
8. Forming apparatus according to any of the preceding claims, characterised in that the flexible membrane (42) is designed such that an inner surface region of the flexible membrane (42) which partially bounds the recess performs, if pressure is applied to the fluid passage (40), a movement which includes a component which is directed radially inwards and a component which is directed parallel to the longitudinal axis (39) of the recess (16) and which is in particular opposed to the termination orifice (41).
9. Forming apparatus according to claim 8, characterised in that the flexible membrane (42) is designed such that the two movement components, which are oriented perpendicular to one another, are at least almost identical in size.
10. Forming apparatus according to claim 8 or 9, characterised in that at least one leg (73, 74) of the U-shaped cross-section of the flexible membrane (42) encloses an acute angle, preferably an angle of less than 80 degrees, in particular preferably an angle of less than 70 degrees and in particular an angle of less than 60 degrees with the longitudinal axis (39) of the recess (16).
11. Forming apparatus according to claim 8, 9 or 10, characterised in that the two legs (73, 74) of the U-shaped cross-section of the flexible membrane (42) are oriented at least almost parallel to one another.
12. Forming apparatus according to any of claims 7 to 11, characterised in that at least one leg (73, 74) of the U-shaped cross-section of the flexible membrane (42) has in a radially outer circumferential region a continuous bead (76), which is designed for a sealing location in the workholder (6).
13. Forming apparatus according to any of the preceding claims, characterised in that, between the flexible membrane (42) and a termination orifice (41), there is provided a conical ring (37), the conical inner surface (52) of which bounds a section of the recess (16) and tapers as the distance from the termination orifice (41) increases.
14. Forming apparatus according to any of the preceding claims, characterised in that the flexible membrane (42) is designed for a touch contact with the hollow body (7) in an annular region which has a width of less than 20 mm, preferably less than 15 mm, in particular preferably less than 10 mm and in particular less than 5 mm and which has a distance of less than 20 mm, preferably less than 15 mm, in particular preferably less than 10 mm and in particular less than 5 mm from a base plane (79) of the hollow body (7) which is defined by the recess (16).
15. Forming apparatus according to any of the preceding claims, characterised in that the workpiece rotary table (3) is assigned a first actuating means (22) in a locking position (25) for initiating a locking movement in the respective workholder (6) and/or a second actuating means (23) in an unlocking position for initiating an unlocking movement and a third actuating means (32) in a machining position for initiating an actuating movement for the at least partial unlocking and the subsequent locking of the hollow body (7) during a cycle of the cyclical linear movement towards the respective workholder (6).

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