WO2007104927A2

WO2007104927A2 - Gripper device

Info

Publication number: WO2007104927A2
Application number: PCT/GB2007/000800
Authority: WO
Inventors: Richard John Hawes
Original assignee: AEW Delford Systems Ltd
Current assignee: Marel Ltd Great Britain
Priority date: 2006-03-16
Filing date: 2007-03-07
Publication date: 2007-09-20
Anticipated expiration: 2008-09-16
Also published as: GB2436100A; GB2436100B; GB0605229D0; WO2007104927A3

Abstract

A method and an apparatus are described for picking and placing a plurality of items as a group for placement in a particular spacing using a robotic arm and gripper device. The claimed method comprises the steps of positioning the device over the items and then lowering (see actuators 10A, 28A, 32A), operating (see actuator 18) and raising (see actuators 10A,28A,32A) each gripper means in turn to pick up the items one by one, until a predetermined number have been picked, moving (see actuator 36) at least one of the gripped items within the device so as to form with the other items the said particular spacing, positioning the group of items over a new location where they are to be deposited, opening the gripper means so as to release (see actuator 18) the items into the new location, and raising (see actuators 10A,28A,32A) the device so as to leave the group of items in the new location. A corresponding pick and place gripper device is claimed which includes a plurality of item-gripping means (12, 14; 20, 22; 24, 26) and drive means (36).

Description

Title: Gripper Device

Field of the invention

This invention concerns a gripping device which can be fitted to a pick and place robot for picking items off a flat surface. It is of particular use for picking randomly positioned items of product from a conveyor and placing items in groups in a receptacle such as a tray or box or thermoform pouch.

Background

If items are picked one at a time the robot has to traverse the distance to the receptacle and back with every piece. It is faster to pick several items at a time and then place all of the items simultaneously depending on the packing format.

A further problem with placing one item at a time is that if the group of items is to be arranged in a particular pattern and/or are a close fit in the receptacle or a container in which they are to be placed, their individual placing has to be very accurate to avoid interference and may be difficult if not impossible using conventional pick and place techniques and devices.

The invention seeks to provide a method and apparatus for picking and placing a group of items especially placement in a particular pattern such as into a receptacle, in which they are to occupy that particular arrangement and/or are a close or tight fit therein.

Summary of Invention

The present invention provides a method of picking and placing a plurality of items as a group for placement in a particular spacing using a robotic arm and gripper device which includes a plurality of independently operable gripper means for separately picking up items, one at a time, comprising the steps of: -

1) positioning the device over the items and then lowering, operating and raising each gripper means in turn to pick up the items one by one, until a predetermined number have been picked,

2) moving at least one of the gripped items within the device so as to form with the other items the said particular spacing,

3) positioning the group of items over a new location where they are to be deposited,

4) opening the gripper means so as to release the items into the new location, and

5) raising the device so as to leave the group of items in the new location.

Where the items are to be a close or tight fit within a container the step of moving the or each item to form the particular pattern may serve to squeeze the group of items into a size and shape which is thereby adapted to fit into an open topped receptacle or container.

Where the items merely have to be left in the new location arranged in a particular way the step of moving the items to form the group does not need to squeeze items but merely position them so as to occupy the particular pattern.

The arrangement of the items may nevertheless involve these being moved into contact.

The invention further provides a pick and place gripper device which includes a plurality of item-gripping means which are adapted to pick up individual items one at a time and hold them as a group within the device by positioning the device over the items and then lowering, operating and raising each gripping means in turn to pick up the items one by one and which further includes drive means for moving at least one of the item-gripping means while holding an item relative to other of the items held by the other item- gripping means, to form an arrangement having a particular spacing of the items while they are held by the device, and further means for releasing the arrangement of items as a group into a new location.

In a preferred embodiment, each item-gripping means is a pair of relatively moveable jaws, with one of the jaws of each pair being of a first width and the other jaw of each pair being of a second but smaller width.

The movement of the item(s) may bring them into contact, or squeeze or compress them into a smaller volume ready for insertion as by lowering as a group into an open topped receptacle, in which they will be a close or tight fit.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a gripper device embodying the invention adapted to pick up three separate items between three pairs of jaws;

Fig. 2 is another view of the device of Fig.1;

Figs. 3 and 4 show the device after the pairs of jaws have been moved into their gripping position, but laterally spaced apart;

Fig. 5 shows the device after the two outer pairs of jaws have been moved sideways towards the central pair, so that items held by the three pairs of jaws are now closer together; and

Fig. 6 shows the device after the pairs of jaws have been opened to release these items into a receptacle.

The gripper as shown in Figs. 1 to 4 is designed to pick up three separate product pieces before placing them in a container. Each of the three sections within the gripper is identical and comprises vertical guide rod and actuator 10, 1OA to allow its pair of gripping jaws 12,

14 to be raised and lowered vertically by an amount equal to at least the product height. This ensures there is no interference with product pieces on a conveyor (not shown) other than when a pair of jaws are to engage one of the pieces (not shown).

Figs. 1 and 2 show the central pair of jaws 12, 14 in their lowered position with the jaws open. A robot (not shown) positions one pair of the jaws on opposite sides of a piece of product and the jaws are closed by a second actuator 18. The section is then raised by operating 1OA. One of the outer sections is then lowered, and the picking process repeated until each of the three pairs of jaws has picked up and all three are holding product pieces in their raised position. This position is shown in Figs. 3 and 4, albeit without pieces of product between the pairs of j aws .

The outer pairs of jaws are denoted by 20, 22 and 24, 26 and their respective guide rods and actuators by 28, 28 A and 30 and 32, 32A and 34. The outer pairs of jaws are moved towards the central pair by actuator 36 so as to close up the picked product pieces.

Fig. 5 shows the outer pairs of jaws pulled in as close as possible to the central pair of jaws, so that the product pieces are tightly packed together.

Fig. 6 shows all the jaws opened to release the product pieces, with the outer pairs still pulled in toward the central pair. Once the product pieces have been released, the outer pairs of jaws are moved away from the central pair by ^"operating actuator 36, so as to adopt the position shown in Figs. 1 and 2, and the device is ready to pick up and arrange another group of product pieces.

Where the product pieces are of a trapezoidal shape and are to be placed alternately so that wide ends are adjacent to narrow ends for optimum use of space, each pair of jaws preferably includes a wider jaw at one end and a narrower jaw at the other end.

This can be seen in Fig. 5 where jaw 20 is wider than 22, 14 is wider than 16 and although not clearly visible, 24 is wider than 26. Jaws 20, 14 and 24 are of the same width and jaws 22, 16 and 26 are likewise of the same, but smaller width.

Although a single actuator 36 is shown, which moves both pairs of jaws 20, 22 and 24, 26 inwardly or outwardly, two separate actuators may be provided each operating between the central section containing jaws 14, 16 and one of the two outer pairs of jaws, so that the latter can be moved relative to the central pair of jaws 14, 16 independently of one another.

Claims

1. A method of picking and placing a plurality of items as a group for placement in a particular spacing using a robotic arm and gripper device which includes a plurality of independently operable gripper means for separately picking up items, one at a time, comprising the steps of: -

5) raising the device so as to leave the group of items in the new location.

2. A method as claimed in claim 1 wherein the step of moving the or each item to form the particular pattern serves to squeeze the group of items.

3. A method as claimed in claim 2 wherein the squeezing of the group of items adjusts the overall size of the group to enable the items to be lowered into an open topped receptacle in which they will be a close or tight fit.

4. A pick and place gripper device which includes a plurality of item-gripping means which are adapted to pick up individual items one at a time and hold them as a group within the device by positioning the device over the items and then lowering, operating and raising each gripping means in turn to pick up the items one by one and which further includes drive means for moving at least one of the item-gripping means while holding an item relative to other of the items held by the other item-gripping means, to form an arrangement having a particular spacing of the items while they are held by the device, and further means for releasing the arrangement of items as a group into a new location.

5. A pick and place gripper device according to claim 4, wherein each item-gripping means is a pair of relatively moveable jaws, with one of the jaws of each pair being of a first width and the other jaw of each pair being of a second but smaller width.