DE102010040642A1 - Magnetic gripper for mounting on e.g. tool holder of handling device utilized in industrial robot, has spacer axially displaced relative to holding magnet between spacing layer for releasing workpiece and grab layer for holding workpiece - Google Patents

Abstract

The gripper (10) has a holding magnet (34) arranged at an axially displaceable input piston (26) for attracting a workpiece (16) to be gripped. An axially displaceable spacer (18) i.e. hollow piston (19), is engaged with the workpiece and axially displaced relative to the magnet between a spacing layer for releasing the workpiece and a grab layer for holding the workpiece. The spacer and the input piston are axially displaced relative to a gripper base (12) that includes a mounting portion (14) for arrangement at a tool receiver, a tool holder or a machine spindle of a handling device.

Description

The invention relates to a magnetic gripper, for example for a Hanhabungsvorrichtung, in particular for mounting on a tool holder.

Such magnetic grippers are used for receiving a (at least partially magnetic) workpiece by means of a handling device, such as an industrial robot.

The aforementioned handling devices have, usually standardized, tool holders or tool holders or machine spindles to which the handling tools can be arranged. In this case, it may be desirable to mount a magnetic gripper directly on a tool holder / tool holder / machine spindle of such a handling device.

However, it should be noted that tool holders / tool holders / machine spindles are usually designed to be stiff and not resilient. If a magnetic gripper is mounted directly (without an axially compensating connecting element) to the tool holder / tool holder / machine spindle of a handling device, there is a risk that the tool holder / tool holder / machine spindle and / or the workpiece surface will be damaged if the actual position of the workpiece to be gripped is not known exactly and the magnetic gripper is brought too close to the workpiece surface.

However, due to manufacturing tolerances or due to, for example, during machining operations on the workpiece remaining material residues (for example, metal shavings) often arise uncertainties regarding the position of the workpiece to be gripped or its surface. Against this background, a gripping device with the possibility of an axial compensation with respect to the gripping direction is desired.

The invention has for its object to provide a magnetic gripper for a handling device, with an improved and - for the handling device and / or the workpiece to be gripped - gentle handling is possible.

This object is achieved by a magnetic gripper with the features of claim 1. This magnetic gripper for a handling device, in particular for mounting on a tool holder, has a holding magnet for attracting a workpiece to be gripped in the direction of the magnetic gripper, as well as an axially displaceable spacer for contact with the workpiece, in particular during the gripping process, and also an axially displaceable compensating piston to which the holding magnet is arranged. It is provided that the spacer is axially displaceable relative to the holding magnet between a distance position for releasing the workpiece and a gripping position for holding the workpiece.

The magnetic gripper serves to receive workpieces in a gripping direction. Along the gripping direction of the spacer and the balance piston is axially displaceable.

With regard to the axial displacement of the spacer, two axial positions relative to the holding magnet are defined:
A gripping position for holding the workpiece and a distance position for releasing the workpiece. However, the spacer is further axially displaceable, even if it is located relative to the holding magnet in the gripping position. The spacer is starting from the distance position initially axially displaceable to an axial position in which it is relative to the holding magnet in the gripping position, but even beyond this position even further axially displaceable about an axial compensation path, wherein the gripping position is maintained.

Characterized in that the holding magnet is arranged on the axially displaceable balance piston, the gripping position - which is defined by a certain position of the spacer relative to the holding magnet - can be provided for the spacer at a variable axial position.

During a gripping process, the magnetic gripper is first placed on the workpiece with a spacer extended in a spacer position. As a result, a prefixing is achieved which prevents, for example, slipping of the workpiece. For gripping the spacer is retracted into the gripping position, in particular by the fact that the magnetic gripper is moved toward in the direction of the workpiece. The movement of the magnetic gripper is predetermined, for example, with a control device of a handling device on which the magnetic gripper is arranged. The magnetic gripper is moved to a predetermined position. After reaching the gripping position of the spacer can be inserted even further axially. It can be maintained relative to the holding magnet by the arrangement of the holding magnet on the axially displaceable balance piston, the gripping position of the spacer.

By means of this floating suspension, deviations of the actual position from the expected position of the workpiece to be gripped by axial displacement of the compensating piston can be achieved with the magnetic gripper according to the invention be compensated. In particular, a hard stop on the workpiece can be avoided. The magnetic gripper can thus be used directly, in particular without an elastic compensating element, in a rigid tool holder / tool holder / machine spindle without the risk of damage to the tool holder / machine spindle / tool holder in the case of manufacturing tolerances or residual material remaining on the workpiece (for example metal shavings) or the workpiece surface is made.

A preferred embodiment results from the fact that the spacer has a driving portion for the balance piston, in particular for a driving stop provided on the compensating piston, and / or for the holding magnet. It is provided that the compensating piston and / or the driving stop and / or the holding magnet is applied to the driving portion when the spacer is in the gripping position. The driving stop may be provided on the balance piston, in particular be formed by the holding piston arranged on the balance piston.

By providing the driving portion is achieved that the compensating piston is taken along by the spacer axially when the spacer is in the gripping position and axially along the direction of the distance position to the gripping position (ie in the gripping direction) is further moved. The spacer is thereby further axially displaced while maintaining the gripping position together with the holding magnet to an axial compensation path.

For further refinement, the gripper has a gripper base part, wherein the spacer and the compensating piston can be displaced axially relative to the gripper base part, in particular in the gripping direction.

In particular, it is advantageous if the gripper base part has, on a region facing away from the spacer, a mounting section, in particular a mounting adapter, for placement on a tool holder or a tool holder or a machine spindle of a handling device.

As a further advantageous embodiment of the invention, it is provided that the spacer has a contact portion for abutment of the workpiece to be gripped, wherein the analageabschnitt brought in the gripping position to the holding magnet, spaced in the distance position of the holding magnet. When the spacer is in the gripping position, a workpiece resting against the abutment portion is so close to the holding magnet that it exerts sufficient attractive force to grasp the workpiece. If the spacer is displaced in the distance position, the workpiece is so far away from the holding magnet, that the attractive force of the holding magnet is small enough to let go.

It is also particularly preferred that the compensation piston has a holding head and a guide portion facing away from the holding head, wherein the holding head faces the spacer and the holding magnet is arranged on the holding head. The guide portion is axially displaceable in particular in a possible gripper base and serves for the axial guidance of the balance piston. In particular, the holding head facing said driving portion of the spacer and the holding magnet is formed as a magnetic disc, which is arranged in the direction of the spacer axially on the holding head the balance piston. The holding head and / or the magnetic disk can then provide said driving stop of the balancing piston for said driving portion of the spacer.

A particularly preferred embodiment results from the fact that the spacer has a piston portion which limits a pressure chamber which can be pressurized to move the spacer in the distance position with a pressure medium, in particular with compressed air or coolant can be pressurized. A hydraulic pressure medium is conceivable. By applying pressure to the space, the spacer forces a picked workpiece away from the holding magnet, thereby releasing the workpiece. This allows a targeted placement of a gripped workpiece.

As a further advantageous embodiment, it is provided that the spacer has one or more discharge channels through which pressure fluid from the pressure chamber, in particular throttled, can escape. The relief channels are in particular formed axially extending in the spacer and open, in particular in the region of an abutment portion of the spacer for abutment of the workpiece in outlet openings, from which the escaping pressure medium can escape. By acting on the pressure chamber with pressure medium, as explained, the spacer moves in the distance position and initiated a release of a gripped workpiece. This process can be further supported by the exiting from the outlet pressure medium. If the discharge channels are designed in such a way that the pressure medium escapes in a throttled manner, a too rapid, abrupt extension of the spacer into the spacing position is also avoided. The relief channels can generally do this as well serve, pressure medium, which is displaced during retraction of the spacer from the distance position into the gripping position from the pressure chamber to dissipate. If the outlet openings are arranged in the area of said abutment section, a cleaning action for the workpiece to be gripped and / or the abutment section of the magnetic gripper can be achieved by the pressure medium flowing out through the outlet openings. As a result, interfering metal chips, for example, can be removed from the magnetic gripper and / or the workpiece.

A further advantageous embodiment results from the fact that the spacer is designed as a hollow piston, wherein the compensating piston is guided at least partially coaxially in the hollow piston. In particular, the compensating piston is guided coaxially in the hollow piston with a holding head, on which the holding magnet is arranged. Conversely, however, it is also conceivable that the balance piston is designed as a hollow piston and the spacer is at least partially coaxially guided in the balance piston.

An advantageous embodiment also results from the fact that the spacer is formed as a hollow piston open on one side with a bottom portion facing away from the balance piston, wherein the holding magnet rests in the gripping position on the bottom portion. In particular, the bottom portion provides the driving portion of the spacer for the balance piston. The side facing away from the holding magnet of the bottom portion facing the workpiece to be gripped and provides a contact portion for the workpiece to be gripped.

For biasing the spacer in the distance position, in particular against a movement in the direction of the gripping position, advantageously a return spring means is provided. During operation of the magnetic gripper thereby an approach of the workpiece is braked to the holding magnets and a hard stop can be avoided. The return spring means is supported in particular on the spacer, in particular in the region of a possible piston portion of the spacer on the one hand and on the other hand on the gripper base.

For further embodiment, a compensating spring means is also provided for biasing the balance piston against displacement into a leveling position. This ensures that a displacement of the holding magnet together with the spacer takes place only when the spacer has been moved into the gripping position and (for example due to a manufacturing tolerance or lying on the workpiece metal chip) is further axially displaced. In particular, the compensation spring means is supported on the one hand on a gripper base, on the other hand on the balance piston. The compensating spring means is formed, for example, as coaxially arranged around the balance piston coil spring.

Further details and advantageous embodiments of the invention will become apparent from the following description, with reference to which shown in the figures. Embodiment of the invention described and explained in detail.

Show it:

1 a gripping device according to the invention spaced from a workpiece with spaced apart extended spacer;

2 Gripping device off 1 with spacers placed on the workpiece;

3 Gripping device from the 1 and 2 with retracted in gripping position spacer;

4 Gripping device from the 1 to 3 with recorded workpiece.

Matching components are in the 1 to 4 provided with the same reference numerals.

The in the 1 to 4 illustrated magnetic gripper 10 has a gripper base 12 with a mounting section 14 , The mounting section 14 serves to the magnetic gripper 10 to mount in a tool holder, not shown, for example, machine spindle, a handling device, not shown.

With the magnetic gripper 10 should a workpiece 16 be recorded.

The magnetic gripper 10 has a spacer 18 on, which as unilaterally open hollow piston 19 is formed, which with a piston portion 20 in the gripper base 12 is guided. The hollow piston 19 has a piston portion 20 remote ground section 22 on which the workpiece to be picked 16 to grip (compare 2 to 4 ). The bottom section 22 thus forms a Analageabschnitt 24 of the spacer 18 for contact with the workpiece to be gripped 16 ,

The magnetic gripper 10 also has a balance piston 26 on. The balance piston 26 has a holding head 28 and a guide section 30 , In the end of the guide section 30 points the balance piston 26 a stop bead 31 on.

The guide section 30 of the balance piston 26 is in an associated guide section 32 of the gripper base 12 axially guided. The gripper base 12 also points in the area of the guide section 32 a stopper section 33 on, to which the stop bead 31 of the balance piston 26 in the in the 1 illustrated basis of the balance piston 26 is applied. The guide section 32 is formed in the manner of a guide tube, in the tube interior of the guide portion 30 of the balance piston 26 is guided axially.

The holding head 28 of the balance piston 26 is in the hollow piston 19 , more precisely in the Hohlkolbenausnehmung, coaxially guided.

At the holding head 28 of the balance piston 26 is a holding magnet 34 arranged, which the floor section 22 of the hollow piston 19 is facing.

The holding magnet 34 serves to exert an attractive force on the workpiece 16 in a gripping direction G (which as arrow in 1 indicated) on the magnetic gripper 10 to.

In 1 is the spacer 18 shown in its distance position. The as investment section 24 serving ground section 22 is from the holding magnet 34 spaced apart from the gripping direction G. The balance piston 26 is in the 1 presented in its basis, in which the stop bead 31 at the stop section 33 is applied.

To the spacer 18 in the in 1 vorzuspannen shown spacing, is a coil spring 36 formed return spring means 38 intended. The coil spring 36 is coaxial about the tubular guide portion 32 of the gripper base 12 arranged and supported on the one hand on the gripper base 12 on the other hand on the piston section 20 of the spacer 18 from.

To the balance piston 26 in his in 1 vorzuspannen base is a coil spring 40 trained compensating spring means 42 intended. The coil spring 40 is coaxial with the holding head 28 facing portion of the guide section 30 arranged. The coil spring 40 supported on the one hand on the holding head 28 on the other hand on the guide section 32 of the gripper base 12 from.

The spacer 18 limited with its piston section 20 in the gripper base 12 a pressure room 50 , The pressure room 50 is with a pressure medium, for example, compressed air or coolant, acted upon. When loading the pressure chamber 50 the spacer learns 18 a force that moves him into the distance position.

The hollow piston 19 has axially extending discharge channels in its walls 52 on. The discharge channels 52 open on the one hand in the region of the piston section 20 in the pressure room 50 on the other hand in the area of the plant section 24 forming ground section 22 in outlet openings 54 , Every discharge channel 52 has such a small flow cross-section that for from the pressure chamber 50 escaping pressure medium, which is the discharge channel 52 flows through, a throttling action is provided.

In the 2 is the magnetic gripper 10 in a further direction of the workpiece 16 lowered position shown. It is the bottom of the section 22 formed investment section 24 of the spacer 18 on the workpiece. This allows the workpiece 16 be pre-fixed to some extent against lateral slippage. The spacer 18 is still in its distance. Therefore, the workpiece is 16 still from the holding magnet 34 spaced and the magnetic gripper 10 still does not exercise to lift the workpiece 16 sufficient force in the gripping direction G from.

To the workpiece 16 with the magnetic gripper 10 to grab, becomes the magnetic gripper 10 starting from the in 2 shown position further in the direction of the workpiece 16 lowered. This will cause the hollow piston 19 starting from its distance position in the gripper base 12 inserted.

First, the coil spring 36 (Return spring means 38 ) from the piston section 20 pressed together. Furthermore, from the pressure chamber 50 Pressure medium displaced, which through the discharge channels 52 throttled escape. As a result, a braking effect for the lowering movement of the magnetic gripper 10 provided.

During axial displacement, the spacer reaches 18 its gripping position when he is so far into the gripper base 12 is inserted that the holding magnet 34 at the bottom section 22 is applied. In the gripping position is the holding magnet 34 very close to the workpiece 16 , whereby an increased attraction for the workpiece on the holding magnet 34 provided.

As long as the spacer 18 not yet in the gripping position, the balance piston remains 26 in the in 1 and 2 illustrated basis, since the balance piston 26 by the compensating spring means 42 is biased in the foundation.

In 3 is the spacer 18 with respect to the holding magnet 34 shown in gripping position: The holding magnet 34 lies at the bottom section 22 at.

However, in the presentation of the 3 the magnetic gripper 10 after reaching the gripping position still further on the workpiece 16 lowered. This can occur, for example, when the position of the workpiece surface deviates from an expected position (for example, because manufacturing tolerances in the production of the workpiece 16 occur).

In this case, the spacer will 18 further inserted axially. Because the balance piston 26 (indirectly via the holding magnet 34 ) at the bottom section 22 is applied, the balance piston 26 upon further axial displacement of the spacer 18 also axially displaced. The balance piston 26 is then from the spacer 18 taken along axially. The bottom section 22 thus provides a driving section 56 of the spacer for a in this embodiment of the holding magnet 34 provided driving stop of the balance piston 26 represents.

Like from the 3 recognizable, is at further axial displacement of the spacer 18 if this is relative to the holding magnet 34 located in the gripping position, the compensating spring means 42 (Coil spring 40 ) pressed together. In this case, the compensation spring means 42 between the holding head 28 and the guide section 32 compressed.

In the described further axial displacement of the balance piston 26 moved from its base into an axial compensation position. In this axial compensation position lifts the stop bead 31 from the stopper section 33 one in the 3 starting with A designated axial compensation path.

The 4 shows the magnetic gripper 10 , which with the gripped workpiece 16 was raised. The spacer 18 is located in the gripping position, in which the holding magnet 34 at the bottom section 22 is applied. By the weight of the workpiece 16 however, it is the spacer 18 pulled back down. This is the balance piston 26 relocated back to its foundation, in which the stop bead 31 at the stopper section 33 is applied.

Finally, the workpiece 16 let go, now the pressure chamber 50 be acted upon with pressure medium. As explained, this will make the spacer 18 from his gripping position of the holding magnet 34 moved away. As a result, this is also the case at the contact section 24 (Bottom portion 22 ) fitting workpiece 16 from the holding magnet 34 away. Letting go of the workpiece 16 can be further supported by the fact that upon exposure to the pressure chamber 50 Pressure medium (in particular compressed air) through the discharge channels 52 and the workpiece 16 facing outlet openings 54 flow out.

Claims (13)

Magnetic gripper ( 10 ) for a handling device - with a holding magnet ( 34 ) for attracting a workpiece to be gripped ( 16 ) to the magnetic gripper ( 10 ), - with an axially displaceable spacer ( 18 ) for contact with the workpiece ( 16 ), - and with an axially displaceable balance piston 26 ), on which the holding magnet ( 34 ), - wherein the spacer ( 18 ) relative to the holding magnet ( 34 ) between a distance position for releasing the workpiece ( 16 ) and a gripping position for holding the workpiece ( 16 ) is axially displaceable. Gripper ( 10 ) according to claim 1, characterized in that the spacer ( 18 ) a driving section ( 56 ) for one on the balance piston ( 26 ) provided driving stop and / or for the holding magnet ( 34 ), wherein the driving stop and / or the holding magnet ( 34 ) to the driving section ( 56 ) is applied when the spacer ( 18 ) is in the gripping position. Gripper ( 10 ) according to one of the preceding claims, characterized in that a gripper base ( 12 ) is provided, wherein the spacer ( 18 ) and the balance piston ( 26 ) relative to the gripper base ( 12 ) are axially displaceable. Gripper ( 10 ) according to the preceding claim, characterized in that the gripper base ( 12 ) a mounting section ( 14 ) for placement on a tool holder or a tool holder or a machine spindle of a handling device, wherein the mounting portion ( 14 ) on a spacer ( 18 ) facing away from the gripper base ( 12 ) is arranged. Gripper ( 10 ) according to one of the preceding claims, characterized in that the spacer ( 18 ) a plant section ( 24 ) for conditioning the workpiece to be gripped ( 16 ), wherein the abutment section ( 24 ) in the gripping position to the holding magnet ( 34 ), in the distance of the holding magnet ( 34 ) is spaced. Gripper ( 10 ) according to one of the preceding claims, characterized in that the Balance piston ( 26 ) a holding head ( 28 ) and one of the holding head ( 28 ) facing away from the guide section ( 30 ), wherein the holding head ( 28 ) the spacer ( 18 ) and the holding magnet ( 34 ) on the holding head ( 28 ) is arranged. Gripper ( 10 ) according to one of the preceding claims, characterized in that the spacer ( 18 ) a piston gate ( 20 ), which has a pressure chamber ( 50 ), which is used to move the spacer ( 18 ) can be pressurized in the distance position with a pressure medium, in particular with compressed air or coolant can be pressurized. Gripper ( 10 ) according to the preceding claim, characterized in that the spacer ( 18 ) one or more discharge channels ( 52 ), by which pressure medium from the pressure chamber ( 50 ), in particular throttled, can escape. Gripper ( 10 ) according to the preceding claim, characterized in that the spacer ( 18 ) a plant section ( 24 ) for conditioning the workpiece to be gripped ( 16 ), and the spacer ( 18 ) in the area of the plant section ( 24 ) one or more outlet openings ( 54 ) into which the discharge channels ( 52 ). Gripper ( 10 ) according to one of the preceding claims, characterized in that the spacer ( 18 ) as a hollow piston ( 19 ) is formed and the balance piston ( 26 ) at least in sections coaxially in the hollow piston ( 19 ) is guided. Gripper ( 10 ) according to the preceding claim, characterized in that the spacer ( 18 ) as a hollow piston open on one side ( 19 ) with a balance piston ( 26 ) facing away from the floor section ( 22 ), wherein the holding magnet ( 34 ) in the gripping position on the bottom section ( 22 ) is present. Gripper ( 10 ) according to one of the preceding claims, characterized in that a return spring means ( 38 ) for biasing the spacer ( 18 ) is provided in the distance position against displacement into the gripping position. Gripper ( 10 ) according to one of the preceding claims, characterized in that a compensating spring means ( 38 ) for biasing the balance piston ( 26 ) is provided against a shift into a balancing position.

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