The present invention relates to a die former and more particularly to a die former utilised in hot creep forming or superplastic forming.
A number of components, such as blades utilised in gas turbine engines, are initially formed in a rough or preformed state and then subsequently processed through additional forming processes such as hot creep forming or superplastic deformation to nearer a final shape as required.
In terms of the method of operation the component 4 is placed in the lower die 1 and typically such that a root part 102 of the component 4 is in position so that an end face 21 engages a stop 11 (which may be referred to as a reciprocal face 11) in a root stop 103 of the die former 100. Furthermore, a trailing edge face 20 of the component 4 engages a stop 10 (which may be referred to as a reciprocal edge face 10) within the die former 100 about a periphery 50 of the mould portion 101.
In the embodiment illustrated the die parts 2, 3 are respectively brought down forcefully and vertically towards the lower die 1. In such circumstances initially the root portion 102 of the component 4 will be held and formed. This will be achieved through the die part 3, as indicated, being forcefully moved down to engage the root part 102 to allow shaping and forming under heat and pressure. The force applied by the die part 3 will cause forming of the root part 102 into its desired, fully formed, final state.
Once located and secured through the die part 3 and the root portion 102 of the component 4, a further upper die part 2 is brought down forcefully and vertically until a tip or blade portion of the component 4 is fully formed. Thus, as illustrated in
It will be appreciated that the objective of a forming process is to fully form a component, such as a turbine blade, from a rough formed shape into the desired shape typically at high temperature, generally 600° C. to 700° C. The process, as indicated, is typically two stage with an initial first die part 3 brought down followed by a second die part 2. The initial rough formed shape will clearly not be in its final form, and may not fit accurately into the die former, either the lower die 1 or the mould parts of the die former; particularly if a twist is to be formed or extended in the component. In such circumstances upon loading the component 4, an operator is required to adjust, typically using long rigid bars, the position of the component 4 in the mould parts to ensure that the component remains against the stops 10, 11 in the mould parts. Unfortunately, as the die part 3 is typically brought down the initial misshaping of the component dislodges the component from its initial position. Therefore, when the die part 3 is fully closed, a tip of a blade (as an example of a component) may be in a poor position relative to the stops 10, 11. When the die part 2 is fully closed, parts of the component 4 can be positioned such that the die parts 2, 3 must be re-opened and the component repositioned before the dies 2, 3 are re-closed again for forming, in an attempt to improve blade tip position and the overall forming process itself. Such inaccuracies create processing problems as well as potential difficulties with final formed component shape accuracy.
In accordance with the invention there is provided a die former and a method of forming a component.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:
As illustrated above, it is the positioning of the component in its rough state prior to forming in a die former (typically at elevated temperatures) which is important in order to achieve accurate final shaping of the component. In accordance with the present invention, about a mould former, which typically comprises opposed mould portions in die parts, pegs or blocks are provided which interlock with each other in order to appropriately force positioning for the component during the forming processes. The further forming processes may extend a twist along an axis of the component.
In accordance with the present invention, pegs 211, 212 are provided respectively in the lower die 201 and in the upper die or at least die part 202 of the upper die. The pegs 211, 212 are in the form of teeth which have a gap between them such that the pegs in the opposed mould portions alternate and fill the gap. In such circumstances, the pegs 211, 212 in opposed lower and upper die parts engage at least a part of the edges 206, 207 of the component 204. The pegs 211, 212 are located about a periphery of mould portion 213 to constrain and locate the component 204, particularly during the forming processes. By alternating the pegs 211, 212, a more consistent barrier or stop is created with the edges 206, 207 of the component 204, in order to ensure location of the component 204 in use without the necessity of opening the dies 201, 203 during the process of forming for repositioning.
In
It will be appreciated that alignment between the lower die 201 and the upper die in the form of die parts 202, 203 is important. As depicted in
It will be understood that the upper die 202 generally is movable, while the lower die 201 is static. The die parts 202, 203 may move down together and may be combined into a unitary die former if required. Alternatively, as is conventional, the die parts 202, 203 may move down separately in sequential order. Furthermore, one of the die parts 202, 203 may move down partially and the other die part 203, 202 then fully engage the component 204, before the first die part 202, 203 again moves into a fully closed position. By such sequencing, positioning of the component from the rough initial shape to the final formed shape may be more accurately achieved. It will be understood that the forming processes utilised with a die former in accordance with the present invention may include hot creep or superplastic forming, and in such circumstances sequencing of movement of the die parts towards the final closed shape may be required for most efficient forming of the final shape.
By the application of the present invention, movement of the component (particularly in the form of a blade) is restricted during the forming processes resulting in a better final position, defined and confined by the periphery defined by the interlocking pegs. Such better control of the position eliminates the need for an operator to continually reposition the component during the forming processes and therefore reduces complexity and potential error in the processes. The pegs, as indicated, take the form of teeth, and so through their interlocking nature, as indicated, will restrict radial movement as well as lateral movement between the lower die and the upper die, again creating better consistency in the former mould in the forming processes.
The number of pegs and the space between the pegs will depend upon operational requirements. Typically a small number of pegs is used, in order to reduce complexity within the die parts and to provide smooth sections for the periphery with limited interengagement gaps. Furthermore, there will be small dimension gaps, in use, between adjacent pegs from the alternating upper and lower die parts. The pegs will be shaped and configured for appropriate interlocking to define the periphery within the former mould created between the die parts. In such circumstances the pegs will have a height sufficient to create such interengagement and provide robust stop barriers at the periphery to the former mould to create the leading and trailing edges as defined above in the component. Greater depth of interengagement will help with alignment and with the strength of the stop barrier created.
The pegs may take a number of cross-sectional profiles. These profiles, for example, may be circular, rectangular, rhomboidal, oblong or obround. Furthermore, the profiles may be in a single plane, two planes/dimensions or fully three-dimensional, either singularly or in combination, to define (through their interengagement) the peripheral stop for the former mould in the die former. The pressure and temperature within the die former creates forming through a hot creep process, and containment of the “flow” of the component during that process is effected by the interengagement at the peripheral edge of the former mould. The material of the component will generally not be sufficiently flaccid that a fluid tight peripheral edge must be created by the interengagement between the pegs. Nevertheless, the gaps between the pegs should be sufficiently small that no unacceptable roughening of the edge is created in use.
As indicated above, dies can be formed in a single piece, in accordance with the present invention, due to the alignment effects of the pegs interengaging with each other. Dies can be utilised for hot creep forming as well as superplastic forming.
Generally, a die former in accordance with the present invention will be specifically shaped for each particular application. In such circumstances, the pegs in each die part or opposed mould portion may be of different sizes and shapes, but reciprocation between opposed pegs, in terms of spaces and gaps between the pegs, in order to define the peripheral edge must be considered. The pegs may be of different depths as required.
It will be understood that it is the corner angle between the peg and mould parts of the die which defines the shape of the edge periphery to the former mould in accordance with aspects of the present invention. In such circumstances this corner edge may be chamfered, radiused or angled in order to create the edge shape as required. Modifications and alterations to the present invention will be appreciated by persons skilled in the technology. In particular, the pegs to create the periphery edge to the former mould in the die parts may be formed from the same material as the die parts and integrally formed with those die parts; or, alternatively, may be inset and secured as required in use. Thus, the pegs may be formed of a different material from the mould itself. It will also be understood that a seaming edge or holder may be created and supported upon the pegs to act as a peripheral edge seal for a component and so help define the final shape of the component in use. In such circumstances the pegs may support that edge feature within the mould.
Number | Date | Country | Kind |
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0915949.2 | Sep 2009 | GB | national |
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Entry |
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British Search Report issued in British Application No. 0915949.2 on Dec. 22, 2009. |
Number | Date | Country | |
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20110061438 A1 | Mar 2011 | US |