The invention relates to a transfer system for transporting work pieces in a press, comprising a transfer rail having a plurality of grippers for gripping the work pieces and a linear mechanism attachable to a press frame of the press for linearly moving the transfer rail with respect to the press frame. The invention further relates to a press, in particular to a press line or multiple-die press, to a method for transporting work pieces in a press and to the use of an articulated robot for transporting work pieces in a press.
An important step of the manufacture of components made of sheet metal is the forming step. Sheet metal parts are formed in a press, such as a hydraulic, hydroforming, mechanical, electrical or pneumatic press, typically including an upper die and a corresponding lower die. The dies are moved against each other, and thereby the work piece arranged in the work space between the dies is formed. The form of the dies determines the impact on the work piece and therefore the resulting form. Usually, a succession of forming steps using differently shaped dies is necessary until the desired form of the sheet metal part is obtained. To perform these steps in an expedient way, a plurality of presses is arranged successively to form a press line, or a press is employed that includes a plurality of die pairs. On one hand, the capacity of the press line or multiple-die press is determined by the capacity of the press, i. e. the time required for carrying out one forming operation. On the other hand however, the capacity significantly depends on the efficiency of the transport of the work pieces from one press station to the next one. It is therefore important to employ a fast transfer system for automatically transporting work pieces from one press station to the next one.
Most presses feature a press frame that supports the lower and upper dies of the press as well as corresponding drives and gears. The work pieces are transferred through a continuous window of the press frame, along a main transfer direction. For this purpose, a transfer system comprising a transfer rail having a plurality of grippers for gripping the work pieces is provided. The work pieces may be gripped by magnetic or suction tools or by grippers that engage with matching recesses or protrusions of the work pieces or of holders attached to the work pieces. Often, such transfer systems are arranged within the window of the press, i. e. substantially on the inner side of the press frame.
However, in the case of small window dimensions there is not enough space for arranging the transfer system within the window and therefore the main portion of the system has to be arranged on the outer side of the press frame. Only the transfer rail runs inside the press window and only a small part of the support of the transfer rail enters the window from the outside of the press. As an example, the “gullWing” transfer system of Güdel pressAutomation, Langenthal, Switzerland is specially adapted for new or retrofit press applications with small window dimensions. This system features a horizontal transfer rail running parallel to the main transfer direction which is attached to the press frame by serial kinematics, comprising in serial progression from the press frame to the transfer rail a swivel axis parallel to the main transfer direction, a vertical linear axis parallel to the main transfer direction, a first horizontal linear axis perpendicular to the main transfer direction and a second horizontal linear axis parallel to the main transfer direction. With respect to the press frame, the transfer rail is linearly moved along the main transfer direction by the second horizontal linear axis. The swivel axis exclusively serves for tipping up the whole system clear of the press, e.g. for allowing access to the bolster for changeover.
The “gullWing” system features an elaborate construction which is well adapted for heavy work pieces and fast dynamics. However, due to its complexity, the construction is rather costly.
It is the object of the invention to create a transfer system pertaining to the technical field initially mentioned, that is adapted to small dimensions of the press window and that is of a simple construction.
The solution of the invention is specified by the features of claim 1. According to the invention, the transfer system features an articulated mechanism for carrying the transfer rail, the articulated mechanism comprising at least three parallel swivel axes, whereby the articulated mechanism is attached to the linear mechanism such that it is linearly moveable with respect to the press frame.
Articulated mechanisms are widely used and cost-effective. They allow for a simple construction of the inventive transfer system. Furthermore, articulated mechanisms allow for a very precise control, the repeatability of such mechanisms may be of the order of 0.1 mm. In the case of presses with small window dimensions, the linear mechanism and the main part of the articulated mechanism may be arranged on an outer side of the press frame, whereby only the transfer rail and the foremost part of the articulated mechanism to which the transfer rail is attached enter the press window. The three parallel swivel axes of the articulated mechanism allow for arbitrarily moving the attachment point of the transfer rail in a plane that is perpendicular to the three axes. At the same time, the orientation of the transfer rail and its grippers in said plane may be as well arbitrarily chosen. The degree of freedom of the linear mechanism must not run in said plane such that by means of the linear mechanism movements of the attachment point leading outside of said plane are enabled.
The inventive transfer system may be used in an inventive method for transporting work pieces in a press, comprising the steps of
In first preferred embodiments of the invention, the linear mechanism comprises a horizontal linear guide attachable to the press frame, in such a way that its linear degree of freedom runs parallel to the main transfer direction of the press. Thereby, the linear mechanism allows for linearly moving the articulated mechanism together with the transfer rail in a direction parallel to the main transfer direction. The remaining degrees of freedom needed for the transfer rail are provided by the articulated mechanism. The linear guide may e. g. be a rail on which a carriage is linearly movable, a slide bearing or a spindle guide.
In the case of a horizontal linear degree of freedom running parallel to the main transfer direction, the at least three swivel axes are preferably oriented parallel to the horizontal linear guide. Therefore, the swivel axes allow for arbitrarily moving the foremost end of the articulate mechanism in a vertical plane perpendicular to the main transfer direction. Together with the linear mechanism, the transfer rail is arbitrarily movable (within certain limits imposed by the actual construction of the mechanisms). At the same time, the orientation of the transfer rail and its grippers within said vertical plane may be arbitrarily chosen, in particular a change of orientation of the transfer rail caused by swiveling motions around the two swivel axes further away from the transfer rail may be compensated by the third, foremost swivel axis. For example, this allows for retaining a horizontal orientation of the transfer rail and its grippers, while moving the transfer rail vertically or horizontally, in a direction perpendicular to the main transfer direction.
Alternatively, the swivel axes are oriented inclined to the horizontal linear guide. In this case, it is still possible to move the transfer rail as needed in a transfer process in a press by combining linear motions along the horizontal linear guide and swiveling motions around the three axis. However, in the case of inclined swivel axes the linear motion along the main transfer direction is not decoupled from the movements in the plane perpendicular to the swivel axes, and therefore swiveling actions to move the transfer rail vertically or horizontally, across the press, have to be compensated by corresponding linear movements along the horizontal guide.
Advantageously, the horizontal linear guide is attachable to the press frame in a position above the work space of the press, and the articulated mechanism is attached to the linear guide in a suspended position. This arrangement avoids obstructions of the lateral openings of the press frame, thereby allowing for easy access to the dies and tools within the press.
Alternatively, the horizontal linear guide is attachable to a base portion of the press frame, and the articulated mechanism is supported on the linear guide.
In second preferred embodiments of the invention, the linear mechanism comprises a vertical linear guide attachable to the press frame, such that the articulated mechanism attached to the linear mechanism is linearly movable in a vertical direction. Furthermore, the at least three swivel axes are oriented parallel to the vertical linear guide. Arranged like this, the swivel axes allow for arbitrarily moving the foremost end of the articulate mechanism, to which the transfer rail is attached, in a horizontal plane. Together with the linear mechanism, the transfer rail is arbitrarily movable (within certain limits imposed by the actual construction of the mechanisms). At the same time, the orientation of the transfer rail and its grippers within said horizontal plane may be arbitrarily chosen, in particular a change of orientation of the transfer rail caused by swiveling motions around the two swivel axes further away from the transfer rail may be compensated by the third, foremost swivel axis. For example, this allows for retaining a horizontal orientation of the transfer rail and its grippers, while moving the transfer rail horizontally.
Again, the linear guide may e. g. be a rail on which a carriage is linearly movable, a slide bearing or a spindle guide.
Preferably, two linear mechanisms with vertical linear guides are attachable to two supports of the press frame. A first articulated mechanism is attached to the first of said linear mechanisms, and a second articulated mechanism is attached to the second of said linear mechanisms. The transfer rail is attached to both the first articulated mechanism and the second articulated mechanism. Attaching the transfer rail to two separate articulated mechanisms, preferably near opposite ends of the transfer rail, ensures stable support of the transfer rail and facilitates the handling of heavy work pieces. Furthermore, the two linear guides may be attached to two vertical supports at opposite ends of the press or press station.
Preferably, the movements of the first articulated mechanism and the second articulated mechanism are synchronized by an external control system, such as an electronic control system for the entire press or a central control system for the transfer system. The control system ensures that the articulated mechanisms (and preferably as well the linear mechanisms) are synchronously actuated. Note, that in the case of two vertically movable articulated mechanisms holding a single transfer rail it is not required to actively control the rotational position of the third swivel axis, adjacent to the transfer rail. This is because the orientation of the transfer rail with respect to a vertical axis is predetermined by the positions of the two attaching elements of the articulated mechanisms.
Alternatively, especially in cases where heavy work pieces are not to be processed, the transfer rail is attached to a single articulated mechanism, preferably in a central region of the transfer rail.
Advantageously, the at least three swivel axes are constructed and arranged such that the articulated mechanism may be swiveled out clear of the press. Thereby, the articulated mechanism is removed from the vicinity of the lateral openings of the press frame and therefore the dies and tools within the press may be more easily accessed. Furthermore, in the case of a horizontal linear mechanism the transfer rail may be swiveled out clear of the press together with the articulated mechanism if the length of the transfer rail does not exceed the corresponding dimensions of the lateral opening. Additionally, the three swivel axes allow for positioning the transfer rail in a position outside of the press which is convenient for maintenance or tool exchange, especially in the case where the three swivel axes are parallel to the main transfer direction.
Preferentially, the articulated mechanism comprises an automatic coupler for coupling the transfer rail. This allows for easy and efficient tool change, in particular in cooperation with feeders or robots for providing the transfer rail to be changed. The couplers may be actuated electrically, hydraulically or pneumatically. They are preferably controlled by an external control system, such as an electronic control system for the entire press or a central control system for the transfer system.
Alternatively, the transfer rails are manually attached to and released from the articulated mechanism.
Preferably, the articulated mechanism is constituted by a robot arm of an articulated robot having at least three parallel swivel axes. Articulated robots are widely available, therefore the inventive transfer system may be assembled from a few stock items, which reduces the system's cost. Often, usual articulated robots feature more than three swivel axes because they are intended for rather complex handling operations. For example, the articulated robots of the roboFlex series of Güdel AG, Langenthal, Switzerland, feature six axes of motion, out of them one linear axis, three parallel swivel axes and two further rotational axes. While such robots are useable in the context of the invention, for transporting work pieces in a press, in principle articulated robots of a simpler construction, having only three parallel swivel axes, suffice. The linear mechanism may be an integrated axis of motion of the robot or it may be provided separately. Similarly, the drive for the linear mechanism may be arranged at the linear guide, at a carriage running along the linear guide, carrying the articulated mechanism, or at the articulated mechanism itself. Finally, using an articulated robot allows for employing existing robot control systems.
Alternatively, the articulated mechanism may be a dedicated mechanism which is not based on existing articulated robots.
Advantageously, the articulated mechanism comprises
Preferably, the first drive is attached to the base, the second drive is attached to the first arm and the third drive is attached to the second arm. This allows for simultaneously minimizing the masses to be moved while preserving constructional simplicity by avoiding complex transmissions. The drives may be supplied with energy (electricity, hydraulic or pneumatic pressure) e. g. by cable drag chains.
Alternatively, only two drives are provided for actuating movements around swivel axes and the movement around the third swivel axis is mechanically synchronized to the movements around the two other swivel axes in such a way that the orientation of the transfer rail is preserved, e. g. by sort of a parallelogram linkage for the attachment point of the transfer rail. The mechanical synchronization is automatically provided in cases where the transfer rail is supported by two articulated mechanisms.
In a press, in particular a press line or multiple-die press, the inventive transfer system may be employed in various ways. Firstly, a single transfer system may be arranged at one side of the press, carrying a usual transfer rail which grips the work pieces on one of their lateral sides or which features a cross-bar that extends across the press. In the case of heavier work pieces, two transfer systems may be arranged across the press, each of them carrying a separate transfer rail for simultaneously gripping the work pieces on two opposite sides. Finally, the two transfer systems arranged across the press may both be attached to a cross-bar which extends across the press and which grips the work pieces from above, e. g. by means of suction or magnetic tools. This arrangement is particularly advantageous in the case of heavy work pieces or if it is required that the work pieces are gripped in a central region, close to the longitudinal axis of the press.
Other advantageous embodiments and combinations of features come out from the detailed description below and the totality of the claims.
The drawings used to explain the embodiments show:
In the figures, the same components are given the same reference symbols.
The work pieces are transported from a die pair to the next adjacent die pair by a transfer system 100. The transfer system 100 comprises a linear mechanism 110, an articulated mechanism 130 and a transfer rail 150 attached to the articulated mechanism 130. The linear mechanism 110 features a horizontal bar 111 that is arranged at the outer side of the press frame 2 in a vertical position above the work space for forming the work pieces between the upper dies 5 and the lower dies 7. The horizontal bar 111 is attached to the two lateral vertical posts 3, 4 by corner profiles 112, 113. It has a substantially square profile and features a horizontal guide rail 114 constructed along its lower surface. A carriage 115 featuring a drive 116 is horizontally running along the guide rail 114 (linear axis J1).
The articulated mechanism 130 is attached to the carriage 115 and features three parallel swivel axes J2, J3, J4 is described in more detail in connection with
The carriage 115 is running on the linear guide rail 114 by means of rolls 117 supported on the protruding portions of the guide rail 114. Drive pinions 118 are pressed against a rack arranged on the lower surface of the guide rail 114, opposite to the rolls 117. The drive pinions 118 are driven by drive 116 in order to move the carriage 115 along the horizontal bar 111. The drive 116 comprises an electric motor which is fed by a cable drag chain which is as such known from prior art and which is not displayed in the Figures for the benefit of lucidity. The cable drag chain may e. g. run in a suitable profile arranged on top of the horizontal bar 111. Thereby, the transfer system 100 and the lateral openings to the press window 10 are not obstructed.
The carriage 115 features an upper portion 119 featuring the rolls 117 and drive pinions 118 as well as a lower portion 120 to which the drive 116 is attached and which features—as part of the articulated mechanism 130—an axle 131 which is oriented horizontally, parallel to the horizontal bar 111 and therefore parallel to the main transfer direction. The axle 131 is coupled to a drive 132 (see
The transfer rail 150 features a longitudinal rod 151 and a plurality of grippers 152 that feature suitable grip means (not displayed) for the work pieces to be transported, such as magnetic or suction tools or other elements that are suitable for gripping the work pieces. The transfer rail 150 and/or the grippers 152 may feature additional (rotational or translational) degrees of freedom such that gripping of the work pieces is facilitated or such that the orientation of the work pieces may be changed during the transfer process.
The
Next, the second arm 136 of the articulated mechanism 130 is rotated counter-clockwise around the second swivel axis J3 in order to lift the transfer rail 150. At the same time, the first arm 133 is rotated counter-clockwise around the first swivel axis J2 to compensate lateral movements. Furthermore, the attaching element 139 is rotated clockwise around the third swivel axis J4 such that a change of orientation of the transfer rail 150 due to the rotation of the second arm 136 is compensated, i. e. the orientation of the transfer rail is preserved.
After the work piece 11 has been deposited on the lower die 7, as shown in
After linearly returning the articulated mechanism 130 to its start position by means of the linear mechanism 110 the situation displayed in
The multiple-die press 1 corresponds to the press described in connection with the first embodiment of the invention (
The work pieces are transported from a die pair to the next adjacent die pair by a transfer system 200 that comprises two linear mechanisms 210.1, 210.2, two corresponding articulated mechanisms 230.1, 230.2 and a transfer rail 250 attached to both the articulated mechanisms 230.1, 230.2. In contrast to the first embodiment, the linear and articulated mechanisms 210.1, 230.1; 210.2, 230.2 are constituted by two stock articulated robots (such as the roboFlex series of Güdel AG, Langenthal, Switzerland) having six axes (one linear axis and five rotational axes) J1-J6. Note that both the first embodiment described above may as well be equipped by stock articulated robots (featuring at least the four needed axes) and the second embodiment may be equipped by dedicated linear/articulated mechanisms as described in connection with the first embodiment.
The linear mechanisms 210.1, 210.2 feature vertical bars 211.1, 211.2 that are arranged at the outer side of the press frame 2 by means of booms 221.1, 221.2. These booms 221.1, 221.2 are attached to the vertical posts 3, 4 by corner profiles 212, 213 and hold the vertical bars 211.1, 211.2 in a suspending manner, in positions that are diagonally outside the vertical posts 3, 4 with respect to the main transfer direction 9 as well as with respect to the transverse direction (see also
The width of the linear guide rail 214.1 attached to the inner surface of the vertical bar 211.1 is slightly larger than the width of the vertical bar 211.1, such that the guide rail 214.1 protrudes from the vertical bar 211.1 on its left as well as right side. The carriage 215.1 is running on the linear guide rail 214.1 by means of rolls 217.1 co-operating with drive pinions 218.1 pressed against a rack arranged on the inner surface of the guide rail 214.1, opposite to the rolls 217.1. The drive pinions 218.1 are driven by drive 216.1 in order to move the carriage 215.1 up and down along the vertical bar 211.1. The drive 216.1 comprises an electric motor which is fed by a cable drag chain which is as such known from prior art and which is not displayed in the Figures for the benefit of lucidity. The cable drag chain may e. g. run in a suitable vertically oriented profile arranged outside or behind the vertical bar 211.1. Thereby, the transfer system 200 and the lateral openings to the press window 10 are not obstructed.
The carriage 215.1 features an outer portion 219.1 featuring the rolls 217.1 and drive pinions 218.1 as well as an inner portion 220.1 to which the drive 216.1 is attached and which features—as part of the articulated mechanism 230.1—a vertically oriented axle 231.1. The axle 231.1 is coupled to a drive (arranged on the bottom side of the inner portion 220.1 and therefore not visible in
The transfer rail 250 attached to both the articulated mechanisms 230.1230.2 again features a longitudinal rod 251 and a plurality of grippers 252 that feature suitable grip means (not displayed) for the work pieces to be transported such as magnetic or suction tools or other elements that are suitable for gripping the work pieces.
Next, the transfer rail 250 is lifted into its upper position by actuating the linear mechanism 210.1. Following this, the second arm 236.1 of the articulated mechanism 230.1 is rotated clockwise around the second swivel axis J3 in order to move the transfer rail 250 along the main transfer direction 9. In order to preserve the transversal position of the transfer rail 250, the first arm 233.1 is at the same time rotated clockwise around the first swivel axis J2. The attaching element 239.1 is rotated counter-clockwise around the third swivel axis J4 in order to compensate its change of orientation due to the simultaneous clockwise rotations of both the arms 233.1, 236.1. Note, that it is not necessary to actively control the rotation around the third swivel axis J4 because the respective orientation of the transfer rail 250 is already defined by the positions of the two attaching elements 239.1 of the two articulated mechanisms 230.1.
After the work piece 11 has been deposited on the lower die 7, the transfer rail 250 is again horizontally retracted from the press 1. This is achieved by rotating the first arm 233.1 of the articulated mechanism 230.1 counter-clockwise around the first swivel axis J2 and by rotating the second arm 236.1 clockwise around the second swivel axis J3. At the same time, the attaching element 239.1 is rotated counter-clockwise around the third swivel axis J4.
After the situation displayed in
As a matter of course, the technical details of the discussed embodiments may be modified without leaving the scope of the invention, e. g. the construction and arrangement of the linear and articulated mechanisms as well as of the transfer rail may be modified. Furthermore, the inventive conveyor system is appropriate for press lines as well as for multiple-die presses of different press widths, lengths and distances. A press or a press line may be equipped with a plurality of serially arranged transfer systems.
The transfer system may be integrated into a variety of press configurations, e. g. independent of the arrangement of the support for the upper dies or of the press bed. The inventive conveyor system is suited for retrofitting of existing press lines or multiple-die presses as well as for integration into newly built appliances. The transfer system is not only suitable for transporting work pieces from a press station to the next adjacent press station but can as well be employed for transporting work pieces from an initial feed station to a first press, to or from an intermediate deposit station or from a final press to a delivery stack or further conveyor.
In summary, it is to be noted that the invention creates a transfer system that is adapted to small dimensions of the press window and that is of a simple construction.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CH2004/000641 | 10/26/2004 | WO | 00 | 9/24/2007 |