EP3448596A1

EP3448596A1 - Transport device having gripping tongs

Info

Publication number: EP3448596A1
Application number: EP17719251.5A
Authority: EP
Inventors: Markus Moser; Simon REIMER; Andreas MARITZ; Andreas Matt
Original assignee: Hatebur Umformmaschinen AG
Current assignee: Hatebur Umformmaschinen AG
Priority date: 2016-04-28
Filing date: 2017-04-25
Publication date: 2019-03-06
Also published as: WO2017186673A1; EA201892456A1; CN109070180A; CH712402A1; TW201742807A; KR20190003519A; JP2019514692A; US20190134695A1

Abstract

In a transport device for moving workpieces in a multiple-stage forming device, gripping tools (32a, 32b) which are configured as gripping tongs for gripping in each case one workpiece are arranged on a gripping tool carrier which can be moved to and fro between the stages of the forming device. The gripping tools (32a, 32b) are assigned in each case one gripping tool drive, arranged on the gripping tool carrier, for the individual actuation of the gripping tools (32a, 32b) for gripping and releasing a workpiece. The gripping tools have in each case two tong arms (32a, 32b) which can be moved towards one another and away from one another in a linear manner by means of the respective gripping tool drive. The gripping tool drives are configured in each case so as to be servo-controlled electrically or hydraulically. Gripping tongs having tong arms (32a, 32b) which can be moved towards one another and away from one another in a linear manner have the advantage in comparison with gripping tongs having pivotable tong arms that they can dip uniformly into the gripping diameter and can act on the workpiece on both sides at the same angle. Positional control of the tong arms is possible as a result of the servo -controlled configuration of the gripping tool drives.

Description

Transport device with tongs

The present invention relates to a transport device for transferring workpieces in a forming device comprising at least two stages according to the preamble of patent claim 1.

In the case of massive forming and also in other forming processes, workpieces frequently pass through several stages of a forming device in succession, with the workpieces being conveyed from stage to stage. In a

Forming the stages are typically a charging stage and various forming stages. For transporting the workpieces from stage to stage are usually equipped with pincer-like gripping tools, working in the machine cycle of the forming device transport devices, the gripping tools simultaneously detect the workpieces, take out of a stage and each next stage, where they release it.

In the known forming devices, the transport movements and the operation of the gripping tools are coupled to the drive train of the forming device - see e.g. the CH 595 155 A.

A generic transport device for converting workpieces in a forming device is described in EP 1 048 372 Bl. In this known transport device, a plurality of gripping tools designed as gripper tongs are each decoupled with their own drive train of the forming device

Gripping tool drive arranged on a longitudinally and transversely to this movable common pliers support, by means of which all gripping pliers

are transported together in each case between two adjacent stages of a forming device back and forth. The gripping tongs comprise two pivot arms, which are driven by a servo motor via kinematic coupling members towards and away from each other pivotally. A problem of conventional transport devices is that at

Process disturbances, e.g. by workpieces inserted incorrectly into the gripping tools or by damaged parts, e.g. torn gripping tools or broken punches etc. are caused, can not be immediately reacted and thus often significant consequential damage to the transport device or the forming device can occur.

Against this background, the invention is based on the object

Transport device of the type mentioned above to be improved so that caused by not correctly inserted into the gripping tools workpieces can be reduced process disturbances.

This object is achieved by the transport device according to the invention, as defined in independent claim 1. Particularly advantageous

Further developments and embodiments of the invention will become apparent from the dependent claims.

The essence of the invention consists in the following: A transport device for converting workpieces in a comprehensive at least two stages

Forming device comprises a gripping tool carrier, which can be moved back and forth between the steps of the forming device, on which at least two gripper tools designed as gripping tongs for gripping a respective workpiece are arranged. The gripping tools is ever one arranged on the gripper tool carrier

Gripping tool drive assigned for the individual actuation of the gripper tools for gripping or releasing a workpiece. The gripping tools designed as gripper tongs each have two by means of the respective

Gripping tool drive linearly towards and away from each other movable pliers arms. The gripper tool drives are each formed electrically or hydraulically servo-controlled.

By forming the grippers with linearly towards each other and away from each other movable gun arms errors when gripping the workpieces can be avoided. Tongs with linear to each other or away from each other movable pliers arms have opposite tongs with swiveling

Pliers arms have the advantage that they dive evenly into the gripping diameter, if they attack on both sides at the same angle on the workpiece. This reduces the risk that workpieces are pushed obliquely into the gripping tongs. Each grasping tool drive can be individually assigned to each grasping forceps

Tongs are individually adjusted and operated. Due to the electrical or hydraulic design of the gripper tool drives, the required

Speed can be achieved while the servo control allows a position control of the gun arms.

Advantageously, the pliers arms are each arranged on a pliers slide slidably mounted in a pliers body, wherein the pliers slides are kinematically connected to one rack and wherein the racks are engaged with a motor driven drive pinion, wherein the pliers carriage and thus the pliers arms by means of the drive pinion movable in opposite directions are. This represents a structurally simple realization of the linear mobility of the gun arms.

Advantageously, the pliers arms are arranged on the pliers carriage relative to these adjustable. As a result, the gun arms can be easily adjusted to the workpieces.

Conveniently, each of the gripper tool drives on an (electric) servomotor with rotary encoder for opening and closing the gripping tools. Servo motors are particularly good because of their control options as Antriebsbzw. Actuators suitable and allow (over the torque) and a

Detection (feedback) of the forces exerted by the gripping tools.

Advantageously, the gripper tool drives associated with a gripper tool control, which is adapted to control the opening and closing movements of the individual gripper tools individually. Conveniently, the gripping tool control is also designed to control the clamping force of the individual gripping tools individually. This allows an optimal adaptation to the respective requirements. In particular, for example, the clamping force when inserting the workpieces in the gripping tools can be set smaller than for transport. The load on the mechanical components is thus only as great as necessary.

In a particularly advantageous manner, the gripper tool control is designed to move one through an empty gripping tool or one incorrectly into the gripper

Gripping tool inserted workpiece conditional process to detect and signal malfunction. Due to this design, process disturbances can be detected early on, thereby reducing consequential damage.

Particularly advantageously, the gripper tools are equipped with a four-point holder formed by pliers shoes for the workpieces to be gripped. This allows a particularly secure mounting of the workpieces and reduces the risk of tilting of the workpieces, especially when inserted into closed

Gripping tools.

In the following the invention will be described in more detail with reference to an embodiment shown in the drawings. Show it:

Figures 1-6 - schematic views and sectional views of a

Forming device in different phases of a workflow;

Fig. 7 is an overall perspective view of the transport device of

Forming device according to Figures 1-6;

Fig. 8 is a front view of the transport device;

Fig. 9 is a side view of the transport device; 10 shows a section through the transport device according to the line XX of FIG. 9; 11 is a perspective view of a gripping tool unit of the transport device;

FIG. 12 is a rear perspective view of the gripping tool unit of FIG.

11;

Fig. 13 is a front view of the gripping tool unit of Fig. 11;

Fig. 14 - a section through the gripping tool unit according to the line

XIV-XIV of Fig. 13;

FIG. 15 shows a side view of the gripping tool unit according to FIG. 11; FIG.

Fig. 16 - a section through the gripping tool unit according to the line

XVI-XVI of Fig. 15;

Fig. 17 - a section through the gripping tool unit according to the line

XVII-XVII of Fig. 15; Fig. 18 is a schematic representation of a control arrangement of

Forming device or its transport device;

Fig. 19 - a schematic path of movement of the gripping tools of

Transport device in normal operation; and

Fig. 20 - a schematic path of movement of the gripping tools in a

Process upset.

The following definition applies to the following description: If reference signs have been given in a figure for the purpose of clarity of drawing, but are not mentioned in the directly related part of the description, reference is made to their explanation in the preceding or following parts of the description. Conversely, to avoid overcharging graphic for the immediate Understanding less relevant reference numbers not entered in all figures. For this purpose, reference is made to the other figures.

The schematic overview representations of FIGS. 1-6 show the parts of the inventive forming device which are relevant for the understanding of the present invention. While Fig. 1 is a front view taken along the line I-I in Fig. 2, Fig. 2 shows a sectional view taken along the line II-II in Fig. 1st

Accordingly, Figures 3 and 5 are front views and Figures 4 and 6 are respective sectional views.

In the exemplary embodiment illustrated, the shaping device designated M as a whole comprises five adjacently arranged steps 110, 120, 130, 140, 150, of which a first stage 110 is a loading stage and the remaining stages 120, 130, 140 and 150 are forming stages. The forming stages 120, 130, 140 and 150 comprise four forming dies 121, 131, 141 and 151 formed in a common die holder 101, four forming tools in the form of press dies 122, 132, 142 and 152 and four ejecting members 123, 133, 143 and 153, with those in the

Forming dies can be ejected from the forming dies by means of the workpieces W formed by the press dies. The loading stage 110 comprises a shearing device 112 for shearing a workpiece W from a bar material (not shown, also supplied by a bar material feeding device) and an ejector 113, with which a workpiece W can be ejected from the shearing device 112. A transport device, generally designated T, serves to transfer the workpieces from one step to the next step of the forming device M. In FIGS. 1-6, only gripper tools, each with a pair of tong arms 32a and 32b, are shown by the transport device T.

During operation of the forming device, the tong-like gripping tools of the transporting device T formed by the pair of gun arms 32a and 32b respectively assume an initial position provided in the loading stage 110 or from the forming dies 121, 131, 141 and 151 of the forming stages 120, 130, 140 and 150 ejected workpiece W on (Figures 1 and 2) and then transport them Workpieces W at the same time to each next level of the forming device M, wherein the received from the last forming stage 150, finished formed workpiece W is released so that it can be removed from the forming device. Figures 3 and 4 illustrate this. In the forming stages 120, 130, 140 and 150, the workpieces W are introduced and shaped by means of the press dies 122, 132, 142 and 152 into the forming dies 121, 131, 141 and 151.

Subsequently, the transport device T moves the (empty) gripper tools back to the starting position shown in Figures 1 and 2. There take the

Gripping tools in each case a new, provided in the loading stage 110 or from the forming dies 121, 131, 141 and 151 of the forming stages 120, 130, 140 and 150 ejected workpiece W and transport these workpieces in turn to the next stage of the forming device, as in Figures 3 and 4 is shown. The entire process takes place in a transport cycle in the machine cycle of the forming device M.

From the above brief description of the conversion process, it will be understood that each gripper tool has a different workpiece in each conversion cycle

transported and each pair of adjacent stages of the forming device is operated by another gripping tool. In the context of the present invention, the conversion of workpieces from stage to stage of the forming device by means of a plurality of gripper tools is to be understood in this sense.

As far as corresponds to the illustrated forming device M in construction and

Functioning conventional forming devices of this type, so that the expert in this regard requires no further explanation.

In the following, with reference to the figures 7-17, the transport device of

Forming M explained in detail. The whole with T designated

Transport device comprises a stationary frame 10, a in or on

Frame 10 movably arranged, plate-like gripping tool carrier 20, which here in the example five gripping tool units 30 carries, and a

Gripper tool carrier drive. The gripping tool units 30 are all arranged at the same distance from a common reference plane E (FIG. 7). A the Greifwerkzeugeinheiten facing front surface of the plate-like

Gripping tool carrier 20 is aligned parallel to the reference plane E. Of the

Gripping tool carrier drive comprises two gripper tool carrier drive motors 55 and 56, which are each designed as servomotors with rotary encoder and gear and are fixedly mounted on the frame 10. Furthermore, the tool carrier drive comprises two crank gear assemblies, each having a crank 51 and 52 and a

Drive rod (connecting rod) 53 and 54 respectively. The cranks 51 and 52 are each fixedly mounted on a rotatable part of the gears of the gripper-tool carrier drive motors 55 and 56, respectively, and are rotationally drivable therefrom. The frame 10 is in practical use on (not shown) machine body of

Forming device M detachably mounted or pivoted away, so that the access to the forming dies and the forming tools in a simple manner

can be released. In the frame 10, two parallel guide rods 11 and 12 are arranged (FIGS. 7-10) whose axes define the reference plane E (FIG. 7). On or on these guide rods 11 and 12, two links 13 and 14 are guided linearly movable in the longitudinal direction of the guide rods. The two links 13 and 14 are also hinged to each one of the two guide rods 11 and 12 pivotally. At their the guide rods from the end facing the handlebars 13 and 14 means

Pivot pairs 15 and 16 (Figures 9 and 10) pivotally mounted on the gripper tool carrier 20. The distance between the two pivot pairs 15 and 16 is equal to the distance between the two guide rods 11 and 12. The distance of the pivot pin 15 of the guide rod 11 is the same size as the distance of the pivot pin 16 of the guide rod 12. The two parallel guide rods 11 and 12 and the two links 13 and 14 thus form together with the gripping tool carrier 20 a Parallelogrammführungsanordnung for the latter, wherein the

Gripping tool carrier 20 in both directions (in the figures up and down) transversely to the longitudinal direction of the guide rods 11 and 12 is deflectable. In Fig. 7, this is symbolized by the double arrow 25. At the same time, the gripping tool carrier 20 is guided along the sliding rods 13 and 14 in the longitudinal direction of the guide rods 11 and 12 along this guided back and forth, which is indicated in Fig. 7 by the double arrow 26. The gripping tool carrier 20 is thus on the one hand parallel guided to the reference plane E linearly movable and on the other hand mounted substantially parallel to the reference plane transversely to its linear mobility deflectable.

The drive rods (connecting rods) 53 and 54 are each rotatably connected at one end to the crank 51 and 52 and at the other end rotatably hinged to the gripping tool carrier 20. By corresponding rotation of the two cranks 51 and 52 by means of the two Greifwerkzeugträgerantriebsmotoren 55 and 56 of the gripping tool carrier 20 (within predetermined limits) can be moved arbitrarily in the direction of the double arrow 26 and / or the double arrow 25.

An advantage of the parallelogram is the fact that the

Gripping tool carrier 20 at its Querauslenkung (pivoting movement around the guide rods) only a small movement perpendicular to it

Deflection movement, ie perpendicular to the reference plane E executes.

In Fig. 19 is a typical movement path of the gripping tool carrier 20 and thus the attached thereto gripping tool units 30 is shown schematically. The self-contained, cyclically traversed motion path 21 comprises four

Motion path sections 21a-21d. The two linear movement path sections 21a and 21c correspond to the linear guided sliding movement of the

Gripping tool carrier 20 along the guide rods in the forward movement or the return movement between the stages of the forming device, the two

Motion path sections 21b and 21d result from the deflection of the

Gripping tool carrier 20 by means of Parallelogrammführungsanordnung. Points 22 and 23 mark the starting position shown in FIG. 1 and the position of the gripping tool carrier 20 shifted by one step as shown in FIG. 3. As FIG. 19 shows, the gripping tool carrier 20 moves along a first linear path of movement (FIG. Movement path section 21a) while the

Return movement of the gripping tool carrier 20 along one of the first linear

Movement path parallel linear trajectory (motion path section 21c) takes place. The distance between the two linear trajectories resulting from the deflection of the gripping tool carrier 20 is selected such that the gripping tool units 30 arranged on the gripper tool carrier 20 and / or their Gripping tools at the level of the second linear movement path outside the engagement region of the forming tools 122, 132, 142, 152 in the forming stages 120, 130, 140, 150 are located, as shown in FIG. 5 can be seen. With 27 a waiting position is marked, which will be returned further below.

The gripper tool units 30 arranged next to one another on the gripper tool carrier 20 are all of the same design. Their structure is apparent from Figures 11-17.

Each gripper unit 30 includes a tong body 31, a pair of movable tong arms 32a and 32b forming a gripper, and a gripper

Gripping tool drive in the form of an (electric) servomotor 33 with rotary encoder and gear, wherein the servo motor is shown only in Figures 9 and 14. The pliers body 31 and the servomotor 33 including gear are each on

Gripping tool carrier 20 mounted. The two tong arms 32a and 32b are movably arranged on the tong body 31.

In the tong body 31 are on three guide rods 34 a, 34 b and 34 c two

Pliers carriage 35a and 35b slidably mounted. The pliers slides 35a and 35b are each kinematically connected via a drive rod 36a and 36b, each with a rack 37a and 37b, so that a movement of the racks causes a co-movement of the pliers carriage and vice versa. The two racks 37a and 37b are engaged with a drive pinion 38 on diagonally opposite sides thereof, which is rotatably driven by the servomotor 33 (via its gear), so that upon rotation of the drive pinion 38, the two racks 37a and 37b move in opposite directions and thus the two tong arms 32a and 32b are moved toward or away from each other. The opening and the closing movement of the gripping tongs formed by the forceps arms 32a and 32b is thus effected by the servomotor 33 or the drive pinion 38 driven by it.

The gripper tool drive may alternatively be designed as a servo-controlled (servo valves exhibiting) hydraulic drive. It is essential that the movement of the grippers on the one hand can be done very quickly and above all position-controlled and the clamping force of the two gun arms on the other hand precisely adjusted or can be regulated and confirmed, just as in the above-described gripper tool drive with electric servomotor is the case.

Pliers shoes 39a and 39b are arranged at the free ends of the two tong arms 32a and 32b, which serve for gripping the workpieces and are fastened interchangeably, so that the gripper tongs can be easily gripped against the shape of the workpieces

Workpieces can be adjusted (Fig. 11). The pliers shoes need not be the same design and / or arranged on all gripping pliers. Preferably, as shown, two pliers shoes are arranged on each pliers arm, which together form a particularly expedient four-point holder for the workpieces to be gripped. On the one hand, such a four-point holder enables a secure holding of the workpieces and, on the other hand, reduces the risk of tilting of the workpieces, in particular when they are inserted into closed gripping tongs. The pliers arms 32a and 32b are detachably connected via a pair of end-toothed plates 40a and 40b to the pliers slides 35a and 35b, respectively (FIGS. 15 and 17). In this way, the forceps arms 32a and 32b can simply be adjusted laterally or in height relative to the forceps slides 35a and 35b, respectively, to provide e.g. adapt the gripping tongs to the respective workpiece.

As shown schematically in FIG. 18, the transport device T also comprises a carrier control 60 for the gripper-tool carrier drive motors 55 and 56 and a gripper-tool controller 70 for the control of the gripper tool carrier drive motors 55 and 56

Gripping tool drive motors 33 of the individual gripping tool units 30. The gripper tool control 70 is adapted to the opening and

Closing movements and the clamping force of the individual gripper tools, here gripper tongs 32a and 32b to control individually. The carrier control 60 calculates the respective rotational positions of the two cranks 51 and 52 required for the movement path 21 of the gripping tool carrier 20 to be shut off and controls them

Servo motors 55 and 56 accordingly. The carrier control 60 also cooperates with a sensor device 65, which is designed to detect a process disturbance caused, for example, by a non-workable or missing workpiece W in the loading stage 110 and to signal the carrier controller 60. The sensor device 65, which is indicated only symbolically in FIGS. 2, 4 and 6, is associated with the rod material supply device (not shown) and may, for example, be a light barrier arrangement. Such

Sensor devices on rod feeders are known per se and e.g. in EP 1 848 556 B1. The sensor device 65 is able to

Rod beginnings and rod ends to recognize. When the sensor device 65 detects a rod end or a rod end, it signals this

Carrier control 60, so that the carrier control knows that the next following rod portion is faulty and must be eliminated or may not be introduced into the forming process. The carrier controller 60 then responds to this process fault in the manner explained in more detail below.

The carrier control 60 and the gripping tool control 70 cooperate with a higher-level control 80, which, inter alia, also establishes the connection to the forming device and specifies at which position of the movement path the gripping tool carrier or its gripping tools should respectively be located. By means of the higher-level control 80, an operator can also

Settings e.g. concerning the movement of the gripping tool carrier or

Enter or change the opening and closing movements of the tongs.

Of course, the functions of the carrier controller 60, the

Gripping tool control 70 and the higher-level control 80 also realized in another configuration, e.g. be summarized in a single controller.

As already mentioned, is in forming equipment, especially

Hot forming, usually supplied to the raw material in bar form, which are then sheared off pieces of suitable length. The rod ends and rod beginnings must not enter into the forming process and must be eliminated. These excreted sections are missing in the

Forming process and generate in the forming empty forming stages, which should be avoided for the reasons explained above. Thanks to the independent, decoupled from the drive train of the forming device drive the gripper tool carrier 20 and arranged on it

Gripping tools 32a, 32b provides the inventive transport device described above, the ability to empty forming stages in one

To avoid forming device.

If e.g. By means of said sensor device 65, a process malfunction is detected, which is due to a missing or not suitable for further processing, auszuscheidendes workpiece W (Figures 5 and 6), sends the

Sensor device 65 a corresponding control command to the carrier control 60 for the Greifwerkzeugträgerantrieb. The carrier controller 60 then causes the gripper tool carrier 20 with the gripper tool units 30 not to follow the usual travel path 21 (FIG. 19), but moves the gripper tool carrier 20 into a waiting position 27 with the workpieces W in the gripper tool units 30 (FIG ). The waiting position is, for example, on the upper movement path section 21c of the gripping tool carrier 20 with the gripper arms 32a and 32b of the gripping implement units 30 above and between the tools 112, 122, 132, 142 and 152 so as to be out of reach thereof. This situation is shown in FIGS. 5 and 6. As a result, the forming tools perform an idle stroke, but this has no negative consequences, since all the forming stages are empty. Preferably, the

Tool cooling interrupted in this phase, so that the tools and the waiting workpieces are not cooled. The faulty workpiece W is eliminated (in a conventional manner).

As soon as the sensor device 65 reports that a workpiece W which is suitable for the forming process will arrive again in the loading stage 110, causes the

Carrier control 60 returns the gripper tool carrier 20 to its original path of travel, with the workpieces in each of them

Forming steps are passed and the gripper tool carrier 20 then moves along its normal path of movement 21 in its starting position 22 shown in Figures 1 and 2, there to pick up workpieces W and then to transport the next respective forming stage. FIG. 20 graphically illustrates the above-described movement sequence of the gripping tool carrier 20 in the event of a process disturbance. The movement of the

Gripping tool carrier 20 in the waiting position 27 takes place along a

Motion path portion 24a and the movement of the gripping tool carrier 20 from the waiting position 27 to the position 23 along a movement path portion 24b. The entire movement path from the position 22 via the waiting position 27 to the position 23 is designated by 24. The movement path sections 24a and 24b do not necessarily have the course shown in FIG. The movement of the gripping tool carrier 20 may, for example, along along more alternative

Motion path sections 24a 'and 24b' take place, which the

Motion path sections 21d and 21c and 21c and 21b of the normal

Motion paths 21 correspond.

By decoupling the transport device from the drive sträng the

Forming device can be set and varied regardless of the stroke of the forming tools duration and way to transport, ventilation and gripping. By venting is meant here the vertical deflection of the gripping tool carrier 20, wherein the ventilation stroke corresponds to the vertical distance between the two movement path sections 21a and 21c. The from the hub of

Forming tools decoupled adjustment of lifting and gripping movement allows individual adaptation to the respective workpieces, whereby the

Machine wear is reduced. Moreover, this also makes it possible, in case of accidents in the tool room, e.g. if a forming part was not completely pushed out of the forming die or a broken punch in the

Forming die gets stuck or a forming part was lost from a gripping tool to respond to the situation and drive the gripping tool carrier 20 with its gripping tool units 30 in a safe position, eg said waiting position 27, and stop the forming device until the fault. This can be prevented that, for example, gripping tools demolished or other consequential damage to the transport device caused. The Greifwerkzeugeinheiten 30 are, as already mentioned, by means of

Gripping tool control 70 individually controllable. As a result, the time for opening and closing can be set individually for each gripper unit. Also, the opening stroke of the gun arms 32a and 32b and the duration of the movement can be matched to the respective workpiece. The same applies to the air movement. This can be optimized for each workpiece in terms of stroke and duration with the aim of acceleration and thus load on the

Keep the construction of the device deep. In contrast, known transport devices with cams must always be designed for the maximum possible stroke with the result that the components at each workpiece or

Forming part of maximum load and thus maximum wear are exposed.

To compensate for shape errors of the blank portion or to provide an eccentric volume predistribution, e.g. In the production of cams, it is necessary to adjust the first or another gripping tongs off-center. In known transport devices to eccentric A actuating elements are used or the pliers shoes are adjusted by trial and error, that the center of the

Workpiece is shifted by the desired amount from the middle. With the transport device according to the invention, the gripper tool carrier 20 can be moved by the desired amount from the center (zero position) by simply inputting the desired values to the higher-level control 80 by means of the gripper tool carrier drive motors 55 and 56. The relevant gripper is then aligned with a centric adjustment and then the

Gripping tool carrier moved back to its zero position. In this way, a gripping tongs or several gripping tongs can be adjusted eccentrically. The remaining grippers are set when the gripper tool carrier 20 is again in the middle (in the zero position).

The clamping or holding force of each gripper unit 30 is determined by means of

Gripping tool control 70 controlled by the torque of the associated servo motor 33 and can be easily adapted in this way to the workpiece to be held and optionally also varied over the movement cycle of the gripping tool carrier. The clamping force can eg when inserting the workpieces in the Tongs are smaller than to be adjusted for transport. The load on the mechanical components is thus only as great as necessary.

Servo motors usually have a rotary encoder for the feedback of the current rotational position to their control. With the encoder, the

Gripper control 70 by simply comparing actual to desired rotational position to determine whether a gripping tool is filled or empty, e.g. if a workpiece has been lost from a gripping tool, so that the forming device can be stopped if necessary. By appropriate training of

Gripping tool control 70 can also process disturbances, e.g. be caused by skewed workpieces in the gripping tools or tearing open the gripping tools are detected. In this case, this signals the gripper tool controller 70 to the carrier controller 60 properly, and the carrier controller 60 then causes the gripper tool carrier 20 to move with the gripper tool units 30 to a safe position, e.g. the said waiting position 27, is driven and stopped there until the process fault is corrected. The risk of tearing open a gripping tool arises, for example, when a workpiece is incompletely pushed out of the die or the press ram breaks and gets stuck in the workpiece. When trying to transport the workpiece, the gripping tool would be torn open. However, the gripper tool controller 70 recognizes this early on and causes the carrier control 60 to retract the

Gripping tool carrier, so that the tearing of the affected gripping tool is prevented. Subsequently, the gripping tool carrier 20 with the

Gripping tool units 30 in a secure position, e.g. the mentioned waiting position 27, driven and stopped there until the process fault is corrected. The

Forming device is naturally stopped during this time. In this way it is possible to react immediately to a process malfunction before major damage occurs. The cooperation of the gripping tool control 70 with the

Carrier control 60 is symbolized in FIG. 18 by the arrow 71.

The gripper tools or gripping tongs of the transport device shown have parallel tong arms 32a and 32b, which are moved linearly toward and away from each other. Such grippers have opposite tongs with pivotable gun arms have the advantage that the pliers shoes immerse evenly in the gripping diameter. If the tong shoes engage the workpiece at the same angle on both sides, they are pressed in by the same amount when the workpiece is inserted. This reduces the risk of a workpiece being pushed obliquely into the gripping tongs.

Claims

claims

1. Transport device for converting workpieces in a at least two stages (110, 120, 130, 140, 150) comprising forming device (M), with a movable between the stages of the forming device to and fro

Gripping tool carrier (20), on which at least two gripper tools (32a, 32b) are arranged for gripping a respective workpiece (W), the gripping tools (32a, 32b) each having a gripper tool carrier (20) arranged gripping tool drive (33) the individual actuation of the

Gripping tools (32a, 32b) for gripping or releasing a workpiece (W) is associated, characterized in that the gripping tools each by means of the respective gripping tool drive (33) linearly toward each other and away from each other movable pliers arms (32a, 32b) and the Gripping tool drives (33) are each formed electrically or hydraulically servo-controlled.

2. Transport device according to claim 1, characterized in that the pliers arms (32a, 32b) are arranged on one in a tong body (31) slidably mounted pliers slides (35a, 35b), that the pliers carriage (35a, 35b), each with a rack (37a, 37b) are kinematically connected and in that the toothed racks (37a, 37b) are in engagement with a motor-drivable drive pinion (38), the tong slides (35a, 35b) and thus the tong arms (32a, 32b) being driven by means of the drive pinion (38). 38) are movable in opposite directions.

3. Transport device according to claim 2, characterized in that the pliers arms (32a, 32b) on the pliers slides (35a, 35b) are arranged relative to these adjustable.

4. Transport device according to claim 1 or 2, characterized in that each of the gripper tool drives a servo motor (33) with rotary encoder for opening and closing the gripping tools (32a, 32b).

5. Transport device according to one of claims 1-4, characterized in that the gripping tool drives (33) is associated with a gripping tool control (70) which is adapted to control the opening and closing movements of the individual gripping tools (32a, 32b) individually.

6. Transport device according to claim 5, characterized in that the gripper tool control (70) is adapted to control the clamping force of the individual gripper tools (32a, 32b) individually.

7. Transport device according to claim 5 or 6, characterized in that the gripper tool control (70) is adapted to a by an empty

Gripping tool or incorrectly introduced into the gripping tool workpiece (W) conditional process to detect and signal.

8. Transport device according to one of claims 1-7, characterized in that the gripping tools (32a, 32b) are provided with a by means of pliers shoes (39a, 39b) formed four-point holder for the workpieces to be gripped.