GB2202827A

GB2202827A - Needle gripping device

Info

Publication number: GB2202827A
Application number: GB08806550A
Authority: GB
Inventors: Alexander James King; William Malcom Nimmo
Original assignee: UK Secretary of State for Trade and Industry
Current assignee: UK Secretary of State for Trade and Industry
Priority date: 1987-03-19
Filing date: 1988-03-18
Publication date: 1988-10-05
Anticipated expiration: 2008-03-18
Also published as: GB2202827B; GB8806550D0

Abstract

Materials, such as fibre-reinforced plastics cloths, are engaged by a device comprising a cylinder 8 having curved needles 12 attached thereto, the needles having a radius of curvature slightly greater than that of the cylinder. On rotation of the cylinder about its axis 7, the tips of the needles enter the material to be engaged. As described, several like devices are mounted on a frame and the cylinder is rotated by sliding movement of a yoke 4, controlled by an actuator rod 5. <IMAGE>

Description

MATERIALS GRIPPING DEVICE AND FRAME This invention relates to materials handling devices and in particular to a needle gripping device which with a number of like devicer incorporated on a frame would be used for carefully lifting and laying sheets of material, and would be particularly suited to being mounted on an industrial robot arm.

The objective of the invention is to provide a means of positively attaching and detaching sheets of woven materials such as Fibre Reinforced Plastic (FRP) cloths, with minimum damage to the structure of the fabric and which means is suitable for incorporation in an automated environment. In such an environment, the materials may be impregnated with resin and require careful handling and accurate placing. Additionally the material may need to be separated from another sheet of material on which it is placed so the device must be sensitive enough to lift off,or peel off, only one sheet of material, whilst at the same time being strong enough to handle the peeling forces and the weight of the materials.

Accordingly the present invention provides a materials gripping device having a cylinder, attached circumferentially on which are curved needles having a radius of curvature slightly greater than that of the cylinder, a means for causing the cylinder to rotate about its axis, such rotation causing the tips of the needles to enter the material on which the device is placed.

To accommodate larger sheets or more accurate placement, a number of materials gripping devices may be located together on a frame to act in coordination with each other.

One embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings: Fig la is a sectional plan view of the device Fig is is a sectional side view of the device Fig lo is a sectional end view of the device Fig 2, is 3 stage sectional drawing of the means for causing the cylinder to rotate.

Fi 3a3* are side view drawing of the frame incorporating the devices.

elg 4 , ls a plan view t-rom the dlrection inaicatea of the frame incorporating the devices.

in Fig3 & The device consists essentially of a cylinder, on which the curved needles are clamped, mounted on an axle each end of which is retained in a yoke which in turn is slidably retained in a housing which also houses an actuating means for sliding the yoke.

The housing (1) of the device has a horizontal slot (3) along each side in which the arms of sliding yoke (4) is retained and may have a cover piece (2) as illustrated. The sliding motion of the yoke (4) is controlled by an actuator rod (5) connected to the yoke (4) at a point mid way between its arms. The actuator rod (5) passes through an end wall of the housing (1) to an actuator (6) adjacent said housing (1). The actuator might be a

activated ram.

The yoke (4) retains the ends of the cylinder axle (7) around which the cylinder (8) may rotate. Parallel to and at a specific radius from the cylinder axle (7), a reaction pin (9) is retained in the cylinder (8) with its ends engaging in vertical guide grooves (11, 10) provided in the inside side walls of the housing (1) below the horizontal slots (3).

The purpose of the reaction pin (9) is to translate the horizontal movement of the yoke and cylinder into a rotary motion, so that the cylinder is rotated as the yoke is pushed or pulled by the actuator.

The cylinder is provided with a number of circumferential shallow grooves (13). Located in these grooves (13) are curved needles (12) with a radius of curvature slightly greater than that re of the cylinder, so that when the needles (12)^retained by their non-pointed ends, the points project slightly from the grooves (13) above the curvature of the cylinder (S). The needles (12) are retained in the grooves (13) by a backing clamp (14). The needles used in this example are individual elements retained in their grooves by the clamp, but could alternatively be a single array or comb of needles.

The way the device is actioned can be seen from the 3 stages illustrated in Figure 2. which show how the reaction Din (9) slides

in its groove (10, ll) > as the cylinder axle (7) is pulled by the actuator (6), and how the needles (12) engage and grip the material.

At Stage I, the yoke is fully extended from the actuator, and the needles are fully withdrawn from the woven material. At Stage II the yoke has been moved horizontally towards the actuator.

Being mounted in the yoke the cylinder axle (7) follows this translation, but the ends of the reaction pin (9) are located in a vertical groove in the housing wall. The pin is forced to move down the grooves (10, 11) and the cylinder rotates about its axle (7).

At this point the tips of the needles (12) engage and enter the material.

At Stage III, further movement of the yoke causes further rotation of the cylinder. This causes the tips of the needles (12) to pass under the sheet of material and to re-enter the material from the underside1 trapping a portion of the material between the needle (12) and the cylinder (7).

Furthermore the rolling action presses the material into the grooves of the cylinder thus provide increased grip between needle (12) and cylinder (7).

The geometry of the needles will affect the depth to which they will pierce and grip the material, and may be pre-set accordingly. This may be done either through pre-selecting the radius of curvature of the needles1 or by adjusting a needle adjustment bar (lug) set into the periphery of the cylinder (7).

To deposit material held securely by the device in a required location, the above procedure is simply reversed and the cylinder rotates in the opposite direction and the needles are retracted from the material.

To accommodate larger sheets or more accurate placement a number of materials gripping devices may be located together on a frame (14).

Typically 4 devicgwould be located near the corners of a rectangular frame as 6hown in fig g Alternatively banks of rollers may be located adjacent to each other and at opposing sides of a frame. It would be preferable for the cylinders to rotate in opposite directions on opposing sides of the frame (14).

The frame (74) on which the devices are mounted may be flexible.

It may for example be made from a thin sheet of steel or aluminium.

This will allow the material under the frame to be lifted unevenly or with more initial force at one end, or even centrally. In the particular embodiment illustrated in Figure 3, the frame (14) on which the devices are mounted is attached (towards its periphery) to a nonflexible frame (15) by pivoting connecting bars (16). Preferably the bars connect the rigid frame (15) to the gripping devices themselves mounted on the periphery of the frame (14). Centrally attached to the frame (15) is an extensible member (17) for causing the flexible frame (14) to distort with respect to the rigid frame (15). This distortion can be used to produce a curve on the frame (14) to enable (t4)

material {o be peeled off a surface,or to enable the material to be laid carefully from the centre first without allowing air-bubbles or other defects in laying to occur.

It will be evident to those skilled in the art that the invention described will apply to other applications beyond gripping heavy woven materials. and that whilst in some instances not all the features described will be required for operation, other applications may dictate that other features well-known in the art will need to be incorporated into the mechanism.

he arrangement described above is particularly suited to heavier woven materials, but the invention can also be used for lighter grades of fabric.

Claims

1. A materials gripping device having a cylinder, attached circumferentially on which are curved needles having a radius of curvature slightly greater than that of the cylinder, a means for causing the cylinder to rotate about its axis, such rotation causing the tips of the needles to enter the material on which the device is placed.

2. A materials gripping device as previously claimed in which the cylinder is provided with shallow circumferential grooves in which the needles are located.

3. A materials handling device as claimed in claim 2 in which the means for the rotation of the cylinder is by the horizontal sliding motion of the cylinder axle.

4. A materials gripping device as claimed in claim 3 in which an array of needles is attached to the cylinder.

5. A materials gripping device substantially as herein described and illustrated.

6. A frame on which a number of materials gripping devices as previously claimed in any preceding claim are located on opposing sides of the frame.

7. frame as claimed in claim 6 on which 4 materials gripping devices are located.

8. A frame as claimed in claim 7 on which the materials gripping devices located on opposing sides are arranged so that the movement of the cylinders is in opposing directions.

9. A frame as claimed in any of claims 6 to 8 which is flexible.

10. A frame as claimed in claim 9 which is attached towards its periphery to a rigid frame by a plurality of linking bars, and attached centrally to the rigid frame by an extensible member.

11. A frame as claimed in claim 10 wherein the extensible member is pneumatically controlled.

12. A frame is claimed in claim 10 wherein the extensible member is resiliently biassed.

13. A frame substantially as herein described and illustrated.