GB2171977A - Gripper - Google Patents

Abstract

A gripper for a robot arm includes a pair of rails 11, 11' spaced apart from one another to support a barrel (B) in a sideways attitude. An array (31) of spring-biassed pins (P) is urged against, and conforms to the profile of, a rim of the supported barrel so as to hold the barrel in a stable position on the rails even if the attitude of the robot arm is changed. <IMAGE>

Description

SPECIFICATION Gripper This invention relates to a gripper for a robot arm and it relates particularly, although not exclusively, to a gripper useful in the handling of beer barrels.

It is convenient to move beer barrels from one location to another by rolling them on ribs formed circumferentially on their sides. The barrels are then stacked in an upright condition in readiness for delivery. Hitherto it has been customary to stack the barrels manually and this has proved to be both a strenuous and time consuming procedure.

It is an object of the present invention to provide a gripper whereby the above-described problem is at least alleviated.

Accordingly there is provided a gripper for a robot arm, the gripper comprising means to support an article and a stabilising arrangement adapted to engage with, and conform to the profile of, a surface region of the article so supported thereby to hold the article in a stable position in relation to the support means even when the attitude of the arm, and so the article, is changed.

The gripper finds particular, though not exclusive, application, in the handling of beer barrels; in this case it is convenient to support the barrels on their sides and to arrange for the stabilising arrangement to engage an exterior surface of the barrel generally in the region of the rim.

In one embodiment the stabilising arrangement comprises an array of contact pins and means to urge the pins against said surface region, the pins being displaceable individually, in opposition to the action of resilient biassing means, thereby to conform to the profile presented by the surface region against which they are urged.

The gripper may also include pick-up fingers adapted to manipulate a spacer board, the board, being wedged between respective pairs of fingers.

In order that the invention may be carried readily into effect one embodiment thereof is now described, by way of example only, by reference to the accompanying drawings of which: Figures 7, lb and ic show respective side, end and perspective views of the gripper, Figures 2a and 2b show respective plan and front views of the stabilising arrangement employed in the gripper of Figures 1, and Figure 2c shows, in detail, a pair of pick-up fingers used in manipulating a spacer board.

Referring to the drawings, the gripper comprises two units 10, 20 each arranged to support a single barrel B. Only one of these units (10) will be described in detail, the other being identical.

Unit 10 comprises a pair of support tubes 11, 11' mounted on a common support frame S which is connected to the robot arm, shown at A. The spacing of the tubes is such that, in the shown position, a barrel can be supported securely on its side, one of the circumferential ribs R being seated firmly against respective collars 12, 12' mounted on the tubes. The collars can be set at any desired position along the tubes to accommodate different barrel sizes.

Although the tubes give adequate support in the shown position they, alone, are not sufficient if the barrel is turned into an upright attitude as. is necessary during stacking. To remedy this deficiency an additional stabilising arrangement 30 is provided.

The stabilising arrangement comprises a pin assembly 31 arranged to slide relative to the support frame S on which it is mounted by means of a suitable bracket 32. The pin assembly comprises a plurality of contact pins P which are carried by a pair of guide plates 34, 35 relative to which the pins may be displaced. Each pin is biassed outwardly towards a fully extended position, defined by an end stop ES on the pin, by a respective coil spring 36 acting between the inner guide plate 34 and an abutment surface 37 on the pin. An hydraulic actuator 38 is coupled to the inner guide plate through a suitable iinkage (not shown) to drive the entire pin assembly against a surface region of a supported barrel.The stabilising arrangement is mounted on the support frame at a position above the support tubes such that the contact pins, when urged outwardly, will engage a surface region of the barrel generally about a section of the rim. The pins contact different parts of the surface region and in doing so are displaced by different amounts, in opposition to the action of the coil springs. Some of the pins contact the barrel wall, some the base and others the rim itself; in effect, the pins conform to the profile presented by the contacted surface thereby to embrace the rim and hold the barrel firmly in position on the support tubes irrespective of its attitude. It will be appreciated that because the pins conform to the contacted surface an adequate hold can be established even when the barrel rim is distorted.

In use of the illustrated gripper, the barrels which are to be stacked are arranged on their sides, in pairs. The support tubes are then introduced under the barrels and raised thereby to lift the barrels off a conveyor in a supported condition.

At this stage the pin assemblies are urged against the barrel rims; thereafter the barrels can be turned into an upright attitude for stacking. Although the illustrated gripper is designed to accommodate two barrels, persons skilled in the art will appreciate readily how the gripper can be adapted to accommodate more than two barrels or only a single barrel.

It has been customary hitherto to place a spacer board over each freshly formed layer in a stack so as to provide an even surface on which a new layer may be formed. To assit in this procedure, the frame member S is provided with two pairs of pick-up fingers 40, 40', one pair at each side of the frame member. One finger 41 in each pair is situated rearwardly of, and somewhat above, the other 42.

In use the forward fingers 42 are initially introduced underneath a spacer board B and the robot arm advanced. The board rides up over the forward finger until an upstanding lug L, normally provided at the corners of a spacer board, engages behind the rear finger 41. The robot arm is then withdrawn with the spacer board wedged between each pair of fingers. To place the board on a layer of-barrels, the above-described procedure is reversed.

It will be understood that a gripper in accordance with the present invention may introduce a considerable degree of automation into otherwise labour intensive procedures.

Claims (5)

1. A gripper for a robot arm, the gripper comprising means to support an article and a stabilising arrangement adapted to engage with, and conform to the profile of, a surface region of the article so supported thereby to hold the article in a stable position in relation to the support means even when the attitude of the arm, and so the article, is changed.

2. A gripper according to Claim 1 wherein said stabilising arrangement comprises an array of contact pins and means to urge the array against said surface region, the contact pins being individually displaceable in opposition to the action of a spring biassing means so as to conform to the profile presented by said surface region against which the pins are urged.

3. A gripper according to Claim 1 or Claim 2 wherein said support means and said stabilising arranged are mounted on a common frame member, the support means comprising a pair of support rails which are spaced apart from one another to support a barrel in a sideways attitude.

4. A gripper according to any one of Claims 1 to 3 provided with pick-up fingers adapted to manipulate a spacer board, the board being wedged between respective pairs of fingers.

5. A gripper for a robot arm substantially as hereinbefore described by reference to the accompanying drawings.