Traditional end effector assemblies on industrial robots make use of the six threaded holes in the end face of the robot turn disk, which is usually in the form of a disk or cylinder on the end of a robot arm, and which can rotate abut its central longditudinal axis. An end effector or tool is simply fitted to the turn disk using the six threaded holes in the end face. The problem with this solution is that the heads of the attachment screws which secure the tool or end effector are often hidden by equipment on the end effector, such as for example, a welding transformer, and this means that the end effector or tool has to be disassembled before it can be removed from the robot arm.

The present invention seeks to provide a more convenient construction of end effector assembly, which will allow tools or end effectors on a robot to be changed quickly and with a minimum of downtime of the robot and the minimum of work by an operator or engineer.

According to the present invention, we provide an end effector assembly for an industrial robot, comprising a robot turn disk, circumferentially extending securing means formed on the circumference of a free end portion of the turn disk, a tool attachment plate having means thereon by means of which tools may be secured thereto, a locking ring arranged to overlie the free end of the turn disk, and having circumferentially extending securing means formed on an internal circumference thereof for co-operation with the circumferentially extending securing means on the turn disk and a radially inwardly extending flange on the locking ring for engaging with the tool attachment late to hold it on the end face of the turn disk. Preferably, keying means are provided to prevent relative rotation between the tool attachment plate and turn disk.

In a preferred arrangement, the securing means on the turn disk is a circumferential groove and the securing means on the locking ring is a flange, there are co-operating inclined surfaces on the groove and flange, and the locking ring is split diagonally into two separable parts which are held together by clamping means, e. g. threaded studs or the like.

The keying means may comprise slots formed in the end face of the turn disk with which projections on the underside of the tool attachment plate engage, or slots formed on both members into which wedges or splines are located, or a co-operating peg and aperture arrangement.

A preferred embodiment of end effector assembly for an industrial robot according to the present invention is now described by way of example with reference to the accompanying drawing which is an exploded perspective view of the assembly.

Referring to the drawing, an end of an arm of a robot is shown generally at 1, the arm, inter alia, being rotatable about its longditudinal central axis A. The arm has a cylindrical end portion terminating in what is known as a robot turn disk 3, which has a plurality of threaded holes formed in the end face thereof. Normally six such holes are provided and three are illustrated at 5 in the drawing. Traditionally, an end effector or tool is secured to the robot arm using threaded studs which engage in the holes 5. The problem with this, however, is that the head of the studs (or other attachment meams) are often hidden by equipment on the end effector.

In accordance with the present invention, a circumferential groove 7 is formed in the free end portion of the robot arm 1, this groove having one of its side walls tapered as shown at 9. A tool attachment plate 11, having a substantially similar diameter to that of the robot turn disk 3 is attached to the free end face of the robot arm 1, i. e. with the underside of the tool attachment plate 11 overlying the face of the turn disk 3 in which the holes 5 are provided, by means of a locking ring 13. While the locking ring 13 could be in the form of a flanged clamping ring having an internal thread engaging an external thread on the free end portion of the arm 1, the preferred and illustrated construction is in the form of a diametrically split ring held together by a pair of threaded studs (not shown), the heads of which are located in respective bores 15 formed in the two ring halves and the threaded shanks of which engage with respective threaded apertures 17. As can be seen from the drawing, the tool attachment plate 11 has a chamfered external rim 19, adapted to co-operate with a chamfered face 21 of a radially inwardly extending flange 23 on the internal periphery of the ring 13, whereas a

further chamfered face 25 is provided on a further radially inwardly extending flange 27 on the ring 13 for co-operation with the tapered wall 9 of the circumferential groove 7.

As will be apparent from the drawing, when the tool attachment plate 11 is placed over the end face of the robot turn disk 3, it is held in place by the locking ring 13. The two halves of the locking ring 13 are assembled together, such that its chamfered faces 21 and 25 engage with the chamfered ring 19 of the plate 11 and the tapered wall 9 respectively, and the constructions of the groove 7, the attachment plate 11 and ring 13 are such that, as the clamping studs to clamp together the two halves of the locking ring are tightened up, so the chamfered faces 21 and 25 and chamfered rim 19 and tapered wall 9 will wedge together, thus causing the plate 11 to be firmly secured to the end face of the turn disk 3.

On its end face, the tool attachment plate 11 incorporates an upstanding or axially projecting annular disk 29, provided with a plurality of threaded apertures 31 therein, by means of which different tools can be connected to the end effector assembly.

However, instead of changing the tools on the tool attachment plate, each different tool may have its own tool attachment plate 11, such as that shown in the drawing, connected thereto and when it is desired to change the tool on the end of the robot arm 1, the tool already fitted to the robot arm can quickly be removed by undoing the studs to split the locking ring 13, whereupon another tool with its tool attachment plate 11 already attached thereto can be fitted.

It will thus be appreciated that the present invention, because the two locking studs (not shown) can be accessed from the side, provides a quick release fitting system and the tool does not have to be disassembled before removal. This thereby minimises downtime of the robot and also reduces maintenance and fitting costs.

The tool attachment plate can have tools attached thereto which, during use, introduce substantial torque forces between the robot arm 1 and plate 11. Accordingly, some form of keying means is preferably provided between the end face of the robot turn disk 3 and the underface of the tool attachment plate 11. This keying means could comprise a plurality of axially projecting stub shafts, adapted to engage within the threaded holes

5 in the end face of the turn disk 3 or alternatively, slots could be formed in the end face of the turn disk 3, which are engaged by projecting splines on the underside of the tool attachment plate 11. These are not shown in the drawing. Alternatively, semi-conical slots could be machined on the outer end face of the disk 3 and on the underface of the tool attachment place 11, these slots being arranged opposite each other and extending radially to the outer circumference of both the plate 11 and disk 3, into which slots wedges could be inserted which are designed to be clamped in position as the locking plate is secured in position. Thus, the wedges would tend to force apart the plate 11 and disk 3, whereas the clamping ring 13 would tend to pull the two parts together, thus ensuring relative rotation between the two parts was impossible.

The provision of the conical slot 9 on the outer circumferential surface and of the means on the end face of the turn disc 3 do not affect the ISO standard (9409) associated with the turn disc.

It will, of course, be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.