EP1048372B1 - Transfer device - Google Patents

Abstract

The workpiece transfer device (1) has at least one gripper (12) with at least one movable clamp plate (18) for grasping the workpiece (2), operated by an individual drive, employing a setting motor (27) and an intermediate transmission, for grasping an releasing the workpiece.

Description

The invention relates to a transport device, especially for moving workpieces, especially in a forming machine for massive forming, according to the preamble of claims 1 and 2. Such a facility is out DE-A-2 741 581.

With massive forming and also with other forming processes workpieces often pass through several stations successively. The stations can, for example, form stages in be a pressing tool, the workpiece then from Must be transported step by step. To serve usually grabs, some of which are also heavyweights Capture parts, take them out of one step and to the next stage where they release it.

Such a transport device is known from US Pat. No. 3,456,814 known, which has several gripper devices, which are attached to a holding rail. each Gripper device is designed like a pair of pliers and has two pivotable towards and away from each other stored jaws. They form two-armed levers, one of which has a lever arm for clamping the workpiece and whose other lever arm is used for actuation. To do this the lever arms are connected to a rack by means of drawers, their back and forth movement into one Swiveling movement of the jaws is implemented. The drawers are arranged so that when the Close the jaws, almost at right angles to the direction of movement the rack. It follows from this a very large reduction and vice versa a very high force gain against the closing of the closing movement Jaws. To operate the jaws are used with the Rack-meshing gears that come from the main press drive are driven here.

The ones that appear on the individual workpieces Retaining forces depend on the tool dimensions that be subject to a certain tolerance.

Another transport device for workpieces in Forming machines are known from DE 2434540 C2. Also in this facility there are several of two Clamping jaws provided mechanical gripping devices are provided, operated from a central drive source become. The grippers are separated by two each two-armed lever formed jaws formed by which each have a lever arm for gripping the workpiece serves, the respective other lever arm articulated with a gear is connected. The gears or tooth segments comb with each other and are of a central drive driven here, the opening and closing of all Gripper causes.

Furthermore, from DE 197 25 765 is a transfer device a multi-stage forming press known in which on a movable Carrier a number of grippers is provided which two gripping jaws and one actuator for each Have gripping jaws in which each gripper has a long Workpiece is assigned to eject and implement and where each gripper grips the gripping jaws of the associated workpiece and the actuator is designed such that the gripping jaws for one with a guide pressure permitting ejection slip and on the other hand with one that carries the workpiece Holding pressure is applied to the workpiece, with each gripper actuator hydraulic and trained is that in a controlled manner the holding pressure is higher than that Leadership pressure is.

The control of the Gripping and holding forces on individual jaws are not targeted possible.

The object of the invention is to improve this To create transport facility.

This task is carried out with the transport device Claim 1 or alternatively solved according to claim 2. The Transport device according to claim 1 has at least one, preferably several gripper devices on which one drive device each individually assigned is. This means that each gripper has its own drive Has. In principle, the gripping movement is therefore independent controllable by the gripping movement of the other grippers, adjustable and controllable. This does not allow only if necessary also a non-synchronous working of the individual gripper, but also control and control the gripping forces, possibly independent of component tolerances.

According to claim 2 is in the transport device as Drive device provided a servomotor. This works via such a gear on the gripping device, that allows a defined power transmission. This means, that within the range of motion of a jaw the ratio between the path of movement of the servo motor and the jaw has a defined finite value. This can be a suitable control of the servomotor defined clamping force or holding force on the workpiece eingestellt.werden.

The servomotor is preferably with a position transmitter connected, which is connected to a control device is to control the gripper device. alternative or in addition, the servomotor can be equipped with one device to detect the force applied by the servomotor be connected, which then also with the control device connected is. The facility to monitor the Clamping force can be, for example, a force sensor based on a Strain gauge, a current sensor in the servomotor Power supply line or other suitable Sensor.

The transport device according to the invention allows a fine control of the movement of the jaws or a Fine control of the jaws on the workpiece exerted force. This is especially true when the gearbox a defined power transmission characteristic without singularities, such as occur with toggle lever gears, having. This not only makes it possible to adapt the Gripping movement at any within the production tolerance irregularities lying on the workpiece, but also the control of the holding force so that damage to the Workpiece can be avoided and still hold securely of the workpiece is made possible. In addition, the Clamping jaws apart from their clamping position and their opening position take on a third position and function, which, for example, lies in guiding the workpiece without clamp it in place. A gripper device holds a workpiece for example above a die, it is possible to To reduce clamping force so that the workpiece from the Jaws slipped between them and in the die enters. This measure makes it possible to simplify the transport curve of the gripping device. For example. it can occur when inserting workpieces into the die the gripper device on the die can be dispensed with to move there.

In a preferred embodiment, the drive source a servo motor is provided, the rotation of which converted into a linear movement by a spindle gear becomes. However, other facilities may be required for converting rotary to linear movements Find application. A roller screw is preferred used even with large transmitted forces has low friction. The linear motion will via a lever gear, i.e. only Transfer two pull tabs to the jaws. Here will preferred that the pull tab with the lever arm of the jaw, with which she cooperates, in the clamped position Jaw encloses approximately a right angle. In this area is the power transmission from the output of the spindle gear on the jaw from the angular position of the jaws relatively independent. The reduction ratio is almost constant in terms of controllability the gripper device accommodates.

The gripper device is preferably with others Gripper devices attached together on a holding rail. This is preferably designed such that it defines a closed interior. The drive device and the gear can be completely in the Interior. Here they are harmful Effects largely protected. This is especially true with regard to any originating from the workpiece Heat radiation in semi-hot forming processes. If necessary, can the interior enclosed by the holding rail be pressurized with compressed air to prevent penetration of disruptive substances and their penetration to the transmission, to prevent the threaded spindle and / or the servomotor.

Fig. 1 eine Transporteinrichtung in einer schematisierten perspektivischen Darstellung,

Fig. 2 die Transporteinrichtung nach Figur 1, in einer quergeschnittenen Darstellung,

Fig. 3 die Transporteinrichtung nach den Figuren 1 und 2, in Draufsicht und in Greifposition,

Fig. 4 die Transporteinrichtung nach Figur 3, in Freigabeposition, in Draufsicht,

Fig. 5 eine angewandelte Ausführungsform der erfindungsgemäßen Transporteinrichtung in Schnittdarstellung,

Fig. 6 die Transporteinrichtung nach Figur 5, in einer schematisierten teilweise geschnittenen Draufsicht, in Greifposition, und

Fig. 7 die Transporteinrichtung nach Figur 6, in Freigabeposition in Draufsicht.

An exemplary embodiment of the invention is illustrated in the drawing. Show it:

1 is a transport device in a schematic perspective view,

2 shows the transport device according to FIG. 1, in a cross-sectional illustration,

3 shows the transport device according to FIGS. 1 and 2, in a top view and in a gripping position,

4 shows the transport device according to FIG. 3, in the release position, in a top view,

5 shows a modified embodiment of the transport device according to the invention in a sectional view,

6 shows the transport device according to FIG. 5, in a schematic, partially sectioned top view, in the gripping position, and

Fig. 7, the transport device according to Figure 6, in the release position in plan view.

A transport device 1 is illustrated in FIG. 1, to transport workpieces 2 through several dies 4, 5 provided in a tool 3 are provided is. One belongs to the transport device 1 Holding rail 7, which is indicated by an arrow 8 Transport direction longitudinally movable and if necessary additionally in one indicated by an arrow 9 Direction is raised and lowered.

The holding rail 7 faces the tool 3 Page 11 one or more gripper devices 12, 14, which are set up to close the workpiece 2 seize and transport station by station.

The gripper devices 12, 14 are identical built up. The following description of the gripper device 12 accordingly relates to the gripper device 14. The gripper device 12 has one provided on the front 11 of the support rail 7 support 15 on, an upper and a lower support plate 16, 17 includes. The carrier 15 has a passage on, in the interior enclosed by the holding rail leads. There are two between the two carrier plates 16, 17 Clamping jaws 18, 19 arranged in the clamping position extend approximately parallel to each other away from the carrier 15. The jaws 18, 19 protrude from the carrier 15 and are corresponding between the carrier plates 16, 17 Pins 21, 22 can be pivoted towards and away from one another stored. On its facing away from the carrier 15, free end are the jaws 18 with receiving means provided for the workpiece 2. For example. carries the jaws 18 a prism on its side facing the workpiece 2 23, while the jaws 19 have a flat contact surface 24 having.

One of the gripper devices is shown in FIGS. 2 and 3 12 associated drive device 26, to which an actuator 27 and a gear 28 belongs. The servomotor 27 is with its output shaft 29 with a threaded spindle 31 connected, on which a threaded bushing 32 sitting. This is connected to a slide 33 which of the servo motor 27 away and towards this in the direction of Axis of rotation of the threaded spindle 31, but parallel against this is displaceable. The slide 33 is there guided in a guide indicated only schematically. On the gripper device 12 facing it He carries pivotable pull tabs 35, 36 with her from the end of the slide 33 pivoted with a lever arm 37a, 37b of the respective jaw 18, 19 are connected. The lever arms 37a, 37b are approximately in the right angle or at an acute angle to the remaining sections extending to the workpiece 2 the jaws 18, 19 oriented. In the closed position, when the prism 23 and the flat surface 24 on the workpiece 2, the lever arms 37a, 37b close with the pull tabs 35, 36 each make a right angle. lower However, deviations are permitted.

The transport device 1 described so far works as follows:

It is assumed that the gripper device 12 initially in the position illustrated in FIG. 4 is. The slide 33 is in a the carrier body 15 largely advanced position. The pull tabs 35, 36 pivot about the lever arms 37a, 37b the clamping jaws 18, 19 far away from the workpiece 2, to release this.

If the workpiece 2 is to be gripped by the gripper device 12 are recorded, the servo motor is controlled so that it, as illustrated in Figure 3, the threaded sleeve 32 and pulls the slide 33 away from the gripper device 12. The pull tabs 35, 36 pivot the clamping jaws 18, 19 by pulling the lever arms 37a, 37b, in Clamping position. The jaws 18, 19 around the 7 with respect to the holding rail, by the bolts 21, 22nd Defined fixed swivel axes swiveled. Find them Clamping jaws 18, 19 on the workpiece 2 and will the servo motor 27 is further controlled, the jaws clamp 18, 19 the workpiece 2 firmly. The torque of the Servo motor 27 is driven by the gear 28 by the threaded spindle 31, the slide 33, the pull tabs 35, 36 and the lever arms 37a, 37b is formed on the workpiece 2 transferred. By controlling the engine torque of the servo motor 27, the clamping force on the workpiece 2 relatively independent of its geometric shape and dimensional accuracy be regulated. This is independent of the Regulation of the gripping device 14 possible. alternative the actuator can be braked in the holding position or hold by a cogging torque without rotation.

Is the workpiece 2 between the jaws 18, 19th clamped, it can be lifted out of the tool 3 be by holding rail 7, for example, in the direction of Arrow 9 is moved vertically. Alternatively, the gripping device 12 the workpiece at the height shown record if, for example, by an operator without any action the gripper device 12 out of the workpiece 3 becomes. By moving the holding rail 7 in the direction the arrow 8, the workpiece 2 can now by means of the transport device 1 transferred to the desired next position become. During this process the clamping force maintained on the workpiece 2 by the servo motor 27 with the output shaft 29 at a standstill so far is that it applies a holding torque from the gearbox 28 is converted into a holding force.

1. Der Klemmzustand in dem der Servomotor 27 die Klemmbacken 18, 19 mit Kraft aufeinander zu und gegen das Werkstück drückt. Die Klemmkraft kann aufrecht erhalten werden, wenn das Getriebe 28 (selbstsperrend ist), in dem der Servomotors 27 abgeschaltet wird oder indem der Servomotor so angesteuert wird, dass er ein Mindestmoment aufbringt.

2. Führen des Werkstücks; die Klemmbacken 18, 19 halten das Werkstück 2 zwischeneinander, klemmen es jedoch nicht fest.

3. Die Klemmbacken 18, 19 geben das Werkstück 2 vollständig frei, indem sie von diesem wegschwenken.

If the workpiece 2 has arrived at the next stage, for example at the die 5, the gripper device 12 stops above this die. For example. the workpiece 2 can now be inserted into the relevant die 5 (or also 4) by a downward movement of the holding rail 9. Alternatively, a downward movement can be dispensed with. For example. the gripper device 12 is merely relaxed, ie the clamping jaws 18, 19 are no longer pressed firmly onto the workpiece 2 without being moved away from it. This can be done by reducing the current supply to the servo motor 27, by switching off a minimum current or by slight rotation in the opposite direction, so that the clamping jaws 18, 19 are moved slightly away from the workpiece 2. The workpiece 2 can now slide into the die (or 4) under the effect of its own weight. Once the workpiece 2 has been released, the clamping jaws 18, 19 can be pivoted away from one another by driving the servomotor 27 accordingly. A distinction is thus made between three states:

1. The clamping state in which the servo motor 27 presses the clamping jaws 18, 19 towards one another and against the workpiece. The clamping force can be maintained if the gear 28 (self-locking), in which the servo motor 27 is switched off, or by driving the servo motor in such a way that it generates a minimum torque.

2. Guide the workpiece; the jaws 18, 19 hold the workpiece 2 between each other, but do not clamp it.

3. The jaws 18, 19 completely release the workpiece 2 by pivoting away from it.

To control the servo motor 27 can on the drive device 27 sensors are provided which the applied, exerted or transferred forces or the position of the servo motor 27 or parts of the transmission Mark 26. For example. can an angle encoder on the servo motor 27 be provided. A path encoder can also be added the slider may be provided. In addition, the motor current be evaluated as a measure of the torque generated. Alternatively, torque or force sensors can be provided become.

The servo motor 27 and the gear 26 can be complete be accommodated in the interior of the rail 7. Any sensors can also be arranged here. This activates and records the Movement of the gripper device 12 or the other control their work from the inside. This can if necessary, pressurized with compressed air, e.g. emerges from the interior at the gripper devices 12, 14 and thus the servo motors 27 and the gear 28 cools. In addition, the air escaping here prevents this Ingress of dirt.

FIGS. 5 to 7 show a modified embodiment the transport device 1 illustrates. So far basic structural and / or functional correspondence with the embodiment described above of the transport device 1, are without renewed Explanation uses the same reference numerals. On the previous description is referenced.

While in the transport device 1 according to the figures 1 to 3, a servo motor 27 is used, the Output shaft 29 arranged approximately above the slide 33 is, the arrangement in the transport device 1 is after 5 to 7 in such a way that the servo motor 27 is arranged laterally next to the slide 33. The threaded spindle 31 thus lies approximately next to the servo motor 27 same height. In addition to the threaded spindle, the gear 26 belongs 31 (roller screw) and the other in In connection with Figure 3 elements already described a gear train 41, which rotates the servo motor 27 by means of three gear wheels 42, 43, 44 on the threaded spindle 31 transmits. The drive builds, in particular if gears 42, 43, 44 with a relatively small diameter be used by using the idler gear 43 becomes possible, quite flat, as a result of which, as from FIG can be seen, a generally flat support rail 7 for Application can come.

On the jaws 18, 19 can, if necessary, and how Exchangeable prisms are shown in FIGS. 6 and 7 23a, 23b can be provided. These allow an easy one Adaptation to different workpieces 2. One Adjustment of the gripper device 12 can usually be omitted. The control device, not further illustrated can control the servo motor 27 so that when it is reached a desired clamping force stops and the clamping force maintains. Alternatively or additionally, a Position control or control can be provided at the different clamping and release positions through programming be specified. Likewise, the clamping forces be set by programming what mechanical Make adjustments unnecessary.

A transport device 1, in particular for forming machines for cold forming or semi-hot forming a holding rail with gripper devices 12, the are each controlled separately via servo motors 27. The for power transmission between the servo motor 27 and jaws 18, 19 of the gripper device 12, 14 provided Gear 26, can be self-locking, but transmit regardless of the rotational movement of the respective servo motor steadily on the jaws 18, 19, thereby swing. For better control or regulation of the gripper device 12, 14, these can be used with sensors for force and / or Position detection must be provided.

Claims (2)

1. Transport device (1) in particular for transferring work pieces (2), in particular in a metal-forming machine with at least one gripping device (12) for take-up of a work piece (2), which has at least one movably disposed clamping jaw (18), and with at least one drive means (26), which is individually assigned to the gripping device (12) in order to individually effect the take-up and release of the work piece (2) of the assigned gripping device (12), wherein the drive means (26) has a servomotor (27) and a gear (28) for transmission of the movement generated by the servomotor (27) to the gripping device (12), wherein the clamping force exerted by the clamping jaws (18, 19) onto the work piece (2) is specifically controllable by the servomotor (27), wherein the clamping jaws (18, 19) are respectively disposed to swivel around a fixed rotational axis (21, 22), characterised in that a lever arm of each clamping jaw is connected to the output of a geared spindle drive (32) via pull straps (35, 36).
2. Transport device (1) in particular for transferring work pieces (2), in particular in a metal-forming machine with at least one gripping device (12) for take-up of a work piece (2), which has at least one movably disposed clamping jaw (18), and with at least one drive means (26), which has a servomotor (27) and a gear (28) for transmission of the movement generated by the servomotor (27) to the gripping device (12), wherein the clamping force exerted by the clamping jaws (18) onto the work piece (2) is specifically controllable by the servomotor (27), wherein the clamping jaws (18, 19) are respectively disposed to swivel around a fixed rotational axis (21, 22), characterised in that a lever arm of each clamping jaw is connected to the output of a geared spindle drive (32) via pull straps (35, 36).

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