GB2134018A

GB2134018A - Apparatus for guiding workpieces

Info

Publication number: GB2134018A
Application number: GB08400419A
Authority: GB
Inventors: Gulabbhai Chhibabhai Mistry
Original assignee: British Nuclear Fuels Ltd
Current assignee: British Nuclear Fuels Ltd
Priority date: 1983-01-14
Filing date: 1984-01-09
Publication date: 1984-08-08
Also published as: GB8400419D0; GB2134018B

Abstract

Workpieces 7 are guided to the tool 4 by a resiliently mounted support guide 6 which accommodates irregularities in the profiles of the workpieces to maintain the axes of the workpieces in alignment with the centre line of the tool. <IMAGE>

Description

SPECIFICATION Apparatus for guiding workpieces The present invention concerns apparatus for guiding a workpiece along a desired path of travel.

It is known to provide guides for directing workpieces into a machine or tool but difficulties can arise in the case of damaged workpieces. For example, in the nuclear industry an initial step in the reprocessing of an irradiated nuclear fuel element requires the removal of the sheathing material from about the fuel. A fuel element can comprise a fuel rod within a sheath or can of Magnox (an alloy of magnesium) and it is customary to store the fuel elements under water for some time prior to commencement of reprocessing operations. As a result the fuel elements can be damaged by corrosion of the Magnox cladding and in many instances the ends of the fuel rods can be totally exposed.

For decanning the fuel by removal of the Magnox cladding it is customary to pass the fuel elements between slitter wheels and into a scraper die. The slitter wheels cut through the can to the fuel and the die removes the cut can from the fuel. The fuel element is fed into the machine and aligned by means of a guide to ensure that the element is coaxial with the centre line of the die.

The reference or datum position for the guide is the outer edge of the sheath or can and this is set for an undamaged fuel element. This ensures that the fuel element is correctly positioned and aligned with respect to the slitter wheels and the scraper die. However if the can is damaged, or broken, or even absent, ths will result in a misalignment of the fuel element with respect to the wheels and die and consequent malfunctioning or complete breakdown of the decanning operation.

According to the present invention apparatus for guiding workpieces into alignment with the centre line of a tool comprises a resiliently mounted support guide arranged in the path of travel of the workpieces into the tool to resiliently accommodate irregularities in the profiles of the workpieces whereby to maintain the axes of the workpieces in alignment with the centre line of the tool.

The invention will be described, by way of example, with reference to the accompanying diagrammatic drawing of an apparatus for decanning nuclear fuel elements.

The drawing depicts upper and lower slitter wheels 1 and 2 respectively symmetrically disposed about centre-line 3 of a scraper die 4. A fixed guide 5, supporting a spring return guide 6, is arranged in front of the slitter wheels 1 and 2 remote from the scraper die 4.

A magnox nuclear fuel element comprises a rod of fuel 7 contained within a Magnox sheath or can 8. The apparatus strips the sheath or can 8 from about the fuel rod 7. The fuel element is fed in the direction of arrow 9 between the slitter wheels and into the die. The slitter wheels cut through the wall thickness of the sheath or can 8 and the die then peels the sheath or can away from the fuel rod as the element is advanced through the apparatus. For successful operation it is required that the leading cross-section of the fuel rod is raised up to and within the area confined by the leading edge 11 of the die 4.

The correct alignment of the incoming fuel element with the centre line 3 of the die can be achieved by a guide which is positioned to support the leading end of the fuel element with its longitudinal axis coaxial with the centre-line 3. As the guide bears against the exterior of the sheath or can then clearly any damage, deformation or in extreme cases complete absence of can at the leading end of the element will result in a misalignment and failure of the element to assume its correct position for entry between the slitter wheels and into the die.

The spring return guide 6 on the fixed guide 5 ensures that a fuel element, irrespective of its outer physical condition, is at all times in alignment with the centre-line 3 as it is advanced between the wheels 1 and 2 and into the die 4.

In operation a fuel element is pushed into the apparatus with its leading end riding up the inclined surface 10 on the fixed guide 5. The spring return guide 6 is normally in the full-line position shown in the drawing, at which position the guide 6 will support the leading exposed end of a fuel rod in alignment with the die. Thus in the case of a damaged fuel element in which the Magnox can about the leading end of the fuel rod has been destroyed to expose the rod, the exposed leading end of the rod rides up the spring return guide and on to the centre-line of the die.

Continued advance feeds the leading end of the rod into the die. When the Magnox sheath or can on the fuel element encounters the guide 6 the latter is depressed downwards as indicated in dotted outline in the drawing. The fuel element continues to advance and the Magnox is cut by the slitter wheels 1 and 2 and removed from about the fuel rod by the die 4. When the trailing end of the fuel element leaves the guide 6 the guide can return to its original position. The guide 6 can accommodate irregularities in the surface of the Magnox sheath.

Likewise, the apparatus can accommodate an undamaged fuel element in which the leading end of the fuel rod is enclosed within an undamaged Magnox sheath or can. As before the leading end of the fuel element rides up the incline on the fixed guide 5 and on to the spring return guide. The advance continues until the fuel element contacts the upper guide wheel 1 and as represented by the dotted outline of the fuel element in the drawing.

As the fuel element is being continually urged towards the die the contact with the wheel 1 produces a reaction to depress the spring return guide 6 whereby to allow the eating end of the element to enter between the wheels 1 and 2.

Thereafter the element is cut by the wheels and advanced into the die for removal of the sheath or can. The spring return guide remains in contact with the exterior of the sheath or can until passage of the trailing end of the element at which the spring return guide returns to its initial position.

The spring return guide 6 therefore allows for and accommodates irregularities in the Magnox can and/or the fuel rod at the leading end of the fuel element whereby the element can be presented to the nose of the die for a successful entry of the fuel rod into the die.

In an alternative arrangement, the guide 6 can be dispensed with and the guide 5 can be modified such that its inclined surface 10 is extended to replace the guide 6. The guide 5 is pivotally mounted in a fixed support block and is urged by spring means to engage the fuel elements. The guide 5 pivots about its axis of support against the restraining action of the spring means to accommodate irregularities in the fuel elements. Such an arrangement functions in a manner similar to that previously described.

Although described in detail with reference to the decanning of nuclear fuel elements it will be appreciated that the apparatus is not confined to this use and that it can find application in other industries which require the alignment of an advancing workpiece with the centre line of a tool.

Claims

1. Apparatus for guiding workpieces into alignment with the centre line of a tool comprising a resiliently mounted support guide arranged in the path of travel of the workpieces into the tool to resiliently accommodate irregularities in the profiles of the workpieces whereby to maintain the axes of the workpieces in alignment with the centre line of the tool.

2. Apparatus as claimed in claim 1 in which the tool comprises a die to receive the workpieces.

3. Apparatus as claimed in claim 1 or 2 including slitter means positioned between the tool and the support guide.

4. Apparatus for guiding workpieces into alignment with the centre line of a tool substantially as herein described with reference to and as illustrated in the accompanying drawing.