GB2030903A

GB2030903A - Workpiece manipulator

Info

Publication number: GB2030903A
Application number: GB7931756A
Authority: GB
Original assignee: Gildemeister AG
Current assignee: DMG Mori AG
Priority date: 1978-09-23
Filing date: 1979-09-13
Publication date: 1980-04-16
Also published as: IT7912744A0; IT1124179B; DE2841528A1; IT7915271V0; FR2436650A1; SE7907858L; GB2030903B

Abstract

A workpiece manipulator having a housing (1) mounting a central wheel (2) and at least three gear wheels (3, 4 and 5) meshed with the central wheel (2). A rotary drive is provided for the central wheel (2) and the shaft of each of the gear wheels (3, 4 and 5) mounts a respective crank arm (11) with a respective clamping member as show by a pin (12) on the free end of each crank arm (11). On rotation of the central wheel (2) the pins (12) can clamp an inner or outer diameter of the workpiece. <IMAGE>

Description

SPECIFICATION Workpiece manipulator The invention relates to a workpiece manipulator.

Workpiece manipulators are widely used in connection with machine tools for picking up, holding and laying down workpieces, and for transportation of workpieces. One previously proposed workpiece manipulator, shown in German Published Specification No 25 30 598, is in the form of a three-jaw clamping chuck, wherein the drive for the mechanically coupled movement of the three different clamping jaws is applied by way of one of the jaws. Provided in this drive arrangement is a clamping cylinder with a short clamping stroke movement which is connected to the respective jaw which is guided in the chuck body, by way of a setting means whereby the chuck can be manually set to suit different workpiece dimensions.

Because the clamping jaws must be guided in the chuck body, the clamping range of such a workpiece manipulator is limited by its very nature, in dependence on the diameter of the chuck body. A workpiece manipulator of this kind is also less flexible, by its very nature, insofar as, whenever the dimensions of the workpieces change, the setting means must be operated for the purposes of re-setting the manipulator.

Because the drive is applied by way of one of the clamping jaws it is not possible to achieve precise central clamping of the workpiece, in view of the elasticity of transmission members.

According to the invention there is provided a workpiece manipulator having at least three gear wheels meshed with a central wheel and rotatable by means of a drive, wherein each gear wheel mounts a crank arm which can be pivoted by rotation of the respective gear wheel and each crank arm mounts a respective clamping member at its free end.

Such a workpiece manipulator, while being of simple construction, can be so constructed that it can manipulate workpieces of different dimensions, within wide limits, without any conversion operation.

Using crank arms which can be pivoted to and fro by way of the drive can provide an extremely long clamping stroke movementforthe clamping members. A workpiece manipulator of this kind can thus be flexible as it can clamp workpieces which lie within widely varying ranges of dimensions, by virtue of its long clamping stroke movement. This flexibility produces its advantages particularly when the workpieces are likely to be produced in relatively short series, and therefore workpieces of varying dimensions are to be handled in relatively quick succession.

The reciprocating pivotal movement of the crank arms makes it possible, inherently in the system, when using the simplest possible clamping members, to provide an internal clamping action and an external clamping action, without any conversion work being involved, that is to say, in this case, changing the clamping members. The crank arms can be simple components which can be mass-produced and with this design the clamping members themselves can also be simple components.

Advantageously the clamping members each have two clamping surfaces of different configurations, similar configurations on the different clamping members facing in the same direction of pivotal movement.

This can provide the advantage that different clamping jobs can be done with the same set of clamping members. Preferably each of the clamping members is a pin, half of the circumference of which is hardened and half of which is left soft. Thus workpieces on which machining has been completed can be gripped by means of the soft half of the clamping pins, while rough parts can be clamped by means of the hardened half of the clamping pins.

Preferably the drive for the pivoting movement of the crank arms is a reciprocable drive connected to the central wheel. This has the advantage of providing a clamping action which is precisely central. If the clamping members are interchangeably secured to the crank arms, the particular clamping members needed, for example even shaped clamping members with two different clamping surfaces, can be fitted into position whereby predetermined groups of workpieces can be clamped.

Advantageously the gear wheels are mounted on shafts on which the crank arms are secured outside a housing of the manipulator. Thus the housing of the manipulator can be of small size, even though the clamping members have a large clamping stroke movement.

The invention is diagrammatically illustrated by way of example in the accompanying drawing, in which: Figure 1 shows a plan view of a workpiece manipulator according to the invention; and Figure 2 shows a view in section taken along line Il-Il of Figure 1.

Referring to the drawing, mounted rotatably in a housing 1 is a central wheel 2. The central wheel is engaged by gear wheels 3, 4 and 5 which are distributed around its periphery at uniform spacings, there being three such gear wheels in the embodiment illustrated though more than three could be provided if desired. The gear wheels 3, 4 and 5 are also mounted within the housing 1 on suitable shafts.

The central wheel 2 is mounted on a shaft 7 whereby it can be driven by a gear wheel 8 provided on the shaft 7 outside the housing 1. The gear wheel 8 can be driven by a toothed rack 9 which can be moved with a reciprocating motion by a piston-cylinder unit 10.

Instead of the drive comprising the gear wheel 8, the toothed rack 9 and the piston-cylinder unit 10, it would also be possible to use a drive comprising a reversible motor mounted directly on the shaft 7.

On the side of the housing 1 which is opposite the drive, crank arms 11 are secured on the ends of the respective shafts of the gear wheels 3, 4 and 5, the shaft ends projecting out of the housing 1 at the above-mentioned side of the housing. The crank arms 11 carry clamping members 12 at their free ends. In the embodiment illustrated, the clamping members 12 are in the form of pins. A particular construction provides that the pins are hardened for one half of their circumference and left soft on the other half, as indicated in Figure 1.

The side of the pins which is left soft can advantageously be used for clamping finished machined workpieces, while the hardened half is used for clamping rough parts. This arrangement thus provides two different clamping surfaces which are so disposed that each one faces towards one of the two directions of pivotal movement of the pivoted levers 1 1.

The clamping members 12 are interchangeably secured to the crank arms 1 1. Thus, instead of the pins, it would be possible to use shaped clamping members, possibly with two clamping surfaces of different configurations, which are then suited to particular groups of workpieces in respect of the clamping surface configuration.

It will be appreciated that the pins may readily be used as clamping members either for internal clampir g of workpieces or for external clamping of workpieces.

For the purposes of clamping a workpiece, the toothed rack 9 is displaced in the respective direction required whereby the central wheel 2 is rotated by way of the gear wheel 8. The gear wheels 3, 4 and 5 are thereby turned through a suitable amount. This causes the crank arms 1 1 to carry out a pivotal movement in the desired direction so that the clamping members 12 come into contact with the workpiece.

In regard to the embodiment illustrated, Figure 1 shows broken-line circles which represent the smallest workpiece diameter 13 which can be clamped and the largest workpiece diameter 14 which can be clamped for the particular crank arms 11 and clamping members 12 shown. This view shows that an extremely wide clamping range can be achieved in the very simple manner described hereinbefore.

The pivotal movement of the crank arms 11 and thus the clamping members 12 can be restricted by stops to ensure that the direction of application of force when clamping workpieces does not become too unfavourable.

When a workpiece manipulator of the abovedescribed kind is used in conjunction with programme-controlled machine tools or production equipment, the drive can be incorporated into the programme in such a way that defined basic positions in respect of the crank arms 1 1 and thus the clamping members 12 can be pre-set by means of the programme, corresponding to the respective workpiece diameters, so that the crank arms 1 1 and the clamping members 12 only have to move over a short distance from the above-mentioned basic positions, to clamp the respective workpiece.

In addition, a rotationally operable angular step measuring means may be associated with the central wheel 2, for measuring the rotary movement of the central wheel. The measurement value produces a measurement signal for the diameter of the workpiece to be gripped, which signal is transmitted to a suitable control means.

Claims

1. A workpiece manipulator having at least three gear wheels meshed with a central wheel and rotatable by means of a drive, wherein each gear wheel mounts a crank arm which can be pivoted by rotation of the respective gear wheel and each crank arm mounts a respective clamping member at its free end.

2. A workpiece manipulator according to claim 1, in which the clamping members each have two clamping surfaces of different configurations, similar configurations on the different clamping members facing in the same direction of pivotal movement.

3. A workpiece manipulator according to claim 2, in which each of the clamping members is a pin, half of the circumference of which is hardened and half of which is left soft.

4. A workpiece manipulator according to any one of claims 1 to 3, in which the drive for the pivoting movement of the crank arms is a reciprocable drive connected to the central wheel.

5. A workpiece manipulator according to any one of claims 1 to 4, in which the clamping members are interchangeably secured to the crank arms.

6. A workpiece manipulator according to any of claims 1 to 5, in which the gear wheels are mounted on shafts on which the crank arms are secured outside a housing of the manipulator.

7. A workpiece manipulator according to any of claims 1 to 6, in which the pivotal movement of the crank arms is restricted by stops.

8. A workpiece manipulator according to claim 4, including rotationally operable angular step measuring means associated with the central wheel.

9. A workpiece manipulator substantially as hereinbefore described and illustrated with reference to the accompanying drawing.