Forming Tool

Abstract

A forming tool (20) it comprises a substrate (21) and a metallic glass layer (23) on at least the working surface (22) of the forming tool (20) wherein the forming tool is one of:a) a forming tool of an extrusion press;b) a die of a wire-drawing machine;c) a roll of a polymer processing unit.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a forming tool, a method of modifying the surface of a work-piece or a ductile compound wherein at least one surface of the work-piece or the ductile compound comes into contact with the surface of a forming tool at least once and a method of structuring the outer surface of a forming tool.[0002]In the materials processing industries there are many types of forming operation. In the metals industry forming operations can include, for example:[0003]an extrusion process which is defined as the process of shaping material, such as aluminium, by forcing it to flow through a shaped opening in a die. Extruded material emerges as an elongated piece with the same profile as the die opening.[0004]a wire drawing process, which is a metal-reducing process in which a wire rod is pulled or drawn through a single die or a series of continuous dies, thereby reducing its diameter. Because the volume of the wire remains the same, the ...

AI Technical Summary

Benefits of technology

[0046]A particular advantage of the invention is that the structured surface of the metallic glass layer can be provided with a very fine deterministic structure. It is a preferred embodiment of the invention that the structured surface be deterministic and a more preferred embodiment that the deterministic structured surface contain features which are sub-micron in size.

[0047]A second aspect of the invention is a method of modifying the surface of a work-piece wherein at least one surface of the work-piece comes into contact with the structured surface of a forming tool at least once, characterised in that the forming tool is comprised of a substrate and a metallic glass layer on at least the working surface of the forming tool and the metallic glass layer possesses a structured surface whereby the structured surface of the metallic glass layer reproduces in the surface of the work-piece.

[0048]The nature of the metallic glass layer in terms of its composition and thickness are typically the same as those described above in connection with the forming tool. Likewise, the structured surface can be stochastic in nature but it is preferred that it is deterministic and even more preferred that it contains features which are sub-micron in size.

[0049]Often forming operations of this nature take place in a number of repeat actions and therefore another embodiment of the invention is that this method involves a plurality of contracts between the work-piece and forming tool. This is often desirable because the transfer of the structural features from the surface of the forming tool to the work-piece is rarely perfect and more than one impression can be needed to generate the final desired surface on the work-piece.

[0050]In addition the transfer of the structure from the forming tool to the work-piece can take place under very low loading such that there is little or no reduction in the thickness of the work-piece. This is particularly useful in embossing operations.

[0051]A preferred embodiment involves the use of this method in the processing of plastic material where the forming tool is a work roll of a polymer processing unit.

Problems solved by technology

In the case of multiple pass embossing, deterministic structures can lead to interference effects whilst stochastic structures generally will not.

In work rolls used in the above mentioned polymer processing, a deterministic structure could be imparted into the surface of the work roll by a machining operation, but this would be expensive and such work rolls have a limited life whereafter they need to be refurbished or re-machined, operations which can be expensive and time consuming.

Furthermore, the quality of indentation of the deterministic structure into the surface of the work-piece can deteriorate over time due to wear of the forming surface of the forming tool leading to variable quality in the final product over long production runs.

In order to create complex diffraction patterns, the cut lines are sub-micron in width and it is not possible with conventional tooling methods to obtain this level of resolution within a deterministic structure directly on the surface of a forming tool.

Eventually forming tools wear out and are either expensive or difficult to refurbish.

Also, it is difficult and sometimes impossible to produce deterministic structures.

It is especially difficult to produce very fine, sub-micron, deterministic structures within the coating on a forming tool.

They do not provide flexibility in the sense of it being easy and straightforward to change the surface of the forming tool.

Images