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Title:
HEAT-TREATMENT METHOD AND APPARATUS
Document Type and Number:
WIPO Patent Application WO/2013/079951
Kind Code:
A1
Abstract:
An apparatus for supporting one or more metal components during heat treatment comprising: a support platform; an elongate member extending from the support platform and removably attached to the support platform; and a locking mechanism which locks the elongate member to the platform, wherein the locking mechanism comprises a plurality of engagement portions pivotally mounted at a first end of the elongate member and arranged to engage with the interior of a bore in the support platform.

Inventors:
SCHMIDT KYLE (GB)
FORTIN REJEAN (CA)
Application Number:
GB2012/052954
Publication Date:
June 06, 2013
Filing Date:
November 30, 2012
Export Citation:
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Assignee:
MESSIER-DOWTY LIMITED (Cheltenham Road East, Gloucester, Gloucestershire GL2 9QH, GB)
International Classes:
F27D3/00; F27D5/00
Domestic Patent References:
WO2005073413A1
Foreign References:
US4815971A
FR2793311A1
US5941700A
KR20030037238A
Other References:
None
Attorney, Agent or Firm:
WARDLE, Callum Tarn et al. (4 More London Riverside, London SE1 2AU, GB)
Download PDF:
Claims:
What is claimed is:

1. An apparatus for supporting one or more metal components during heat treatment comprising:

a support platform;

an elongate member extending from the support platform and removably attached to the support platform; and

a locking mechanism which locks the elongate member to the platform, wherein the locking mechanism comprises a plurality of engagement portions pivotally mounted at a first end of the elongate member and arranged to engage with the interior of a bore in the support platform.

2. The apparatus as claimed in claim 1, wherein the locking mechanism comprises at least three of said engagement portions.

3. The apparatus as claimed in claim 1 or 2, wherein the engagement portions are biased radially inward into an unlocked position.

4. The apparatus of claim 3 further comprising a lock plunger disposed within the elongate member and arranged to be movable along the longitudinal axis of the elongate member, the locking plunger being moveable into a locked position in which the lock plunger holds the plurality of engagement portions radially outward.

5. The apparatus as claimed in claim 1 or 2, wherein the engagement portions are biased radially outward into a locked position.

6. The apparatus as claimed in any of claims 1 to 5 further comprising an actuator for actuating the locking mechanism.

7. The apparatus as claimed in any preceding claim, further comprising a guide attached to the platform arranged to receive the elongate member therein.

8. The apparatus as claimed in claims 1 to 7, further comprising a sensor to verify if the elongate member is attached to the support platform.

9. The apparatus as claimed in claim 8 wherein the sensor determines the position of the plurality of engagement portions relative to interior of the bore in the support platform.

10. The apparatus as claimed in claims 8 or 9 wherein the sensor determines the position of the lock plunger relative to the plurality of engagement portions.

11. A method for the heat- treatment of metal components comprising:

positioning a metal component on a heat-treatment apparatus according to any preceding claim;

transferring the heat-treatment apparatus into a heat treatment furnace; heat-treating the metal element;

removing the heat-treatment apparatus from the heat-treatment furnace; disengaging the elongate member from the support platform.

12. The method as claimed in claim 11 further comprising:

before heat treating the metal component, disengaging the elongate member from the support platform and removing it from the heat-treatment furnace;

after heat treating the metal element, reengaging the elongate member with the support platform.

Description:
Heat-treatment method and apparatus

Field of the Invention

This invention relates to a method and apparatus for heat-treatment of metal components. Background In order to ensure the desired strength of certain alloys, they undergo a heat treatment process which involves heating a component above its transformation temperature range and then quenching it (cooling it) to a temperature substantially below its transformation range. This process can be performed to normalise an alloy (refine grains which have been deformed through cold work) or to austenise an alloy (force a phase change to harden the alloy). Some alloys are quenched in oil (rapidly cooled) while others are quenched in air (slowly cooled).

During the heat treat of some large components for aircraft landing gear, the components are positioned on a heat-treatment apparatus comprising a lightweight platform and a heavy central core designed to withstand the load of heavy metal components. The heat-treatment apparatus, complete with the components to be heat-treated, is lifted into a furnace, the components are heat-treated, and the apparatus is then lifted out of the furnace and stood to cool in air. During this cooling process the treated components are left attached to the heat-treatment apparatus.

It is important for the cooling rate of the components to be as uniform as possible throughout the cross-section of each heat-treated component, to minimise any physical distortion that may arise due to uneven contraction rates of the metal. However, due to its large thermal mass, the central core of the heat-treatment apparatus acts as a residual heat source which continues to heat one side of each affixed component during cooling. This causes a differential in the cooling rate across the cross-section of the components, leading to their physical distortion. A need therefore exists for a means to increase the uniformity of cooling rates during air cooling (quenching) of metal components in order to minimize distortion during the heat- treatment process. Summary

In accordance with a first aspect of the present invention, there is provided an apparatus for supporting one or more metal components during heat treatment comprising: a support platform; an elongate member extending from the support platform and removably attached to the support platform; and a locking mechanism which locks the elongate member to the platform, wherein the locking mechanism comprises a plurality of engagement portions pivotally mounted at a first end of the elongate member and arranged to engage with the interior of a bore in the support platform. Accordingly, during air cooling (quenching) of heat-treated components, the elongate member of the heat-treatment apparatus can be removed from the vicinity of the cooling components. This means that any residual heat from central core does not affect the uniformity of cooling rates of the one or more metal components which may otherwise result in physical distortion during the heat-treatment process. Since physical distortion is minimized, pre heat-treated components can be made to more precise dimensions before heat-treatment, without the risk of being written off due to impermissible warping during the cooling process. Further, machining of the much harder post heat-treated components can be kept to a minimum, since the majority of the milling work is done before heat-treat, with only minor refinements being required post heat-treatment.

Preferably, the locking mechanism comprises at least three of said engagement portions.

Advantageously, the engagement portions are biased radially inward into an unlocked position.

Alternatively, the engagement portions are biased radially outward into a locked position. The apparatus may further comprise a lock plunger disposed within the elongate member and arranged to be movable along the longitudinal axis of the elongate member, the locking plunger being moveable into a locked position in which the lock plunger holds the plurality of engagement portions radially outward.

Preferably, the apparatus further comprises an actuator for actuating the locking mechanism.

Advantageously, the apparatus further comprises a guide attached to the platform arranged to receive the elongate member therein.

Preferably, the apparatus further comprises a sensor to verify whether or not the elongate member is attached to the support platform. Accordingly, an indication as to whether the central core and support platform are attached to one another may be communicated to an operator. In embodiments comprising a plurality of engagement portions, the sensor may determine the position of the engagement portions relative to the interior of the bore in the supporting platform. Where a lock plunger is incorporated into the design, the sensor may determine the position of the lock plunger relative to the plurality of engagement portions. In accordance with a second aspect of the invention, there is provided a method for the heat-treatment of metal components comprising: positioning a metal component on a heat- treatment apparatus according to claims 1 to 12; transferring the heat-treatment apparatus into a heat treatment furnace; heat treating the metal element; removing the heat-treatment apparatus from the heat-treatment furnace; and disengaging the elongate member from the support platform.

Preferably, the method further comprises, before heat treating the metal component, disengaging the elongate member from the support platform and removing it from the heat- treatment furnace; and after heat treating the metal element, reengaging the elongate member with the support platform.

Brief Description of the Drawings By way of example only, embodiments of the invention will now be described by reference to the accompanying drawings, in which:

Figure 1 is a diagram of a conventional apparatus used to support metal components during heat treatment.

Figure 2 is a diagram of the apparatus of Figure 1, illustrating how metal components are positioned on the apparatus.

Figure 3a is a diagram of a heat- treatment apparatus according to an embodiment of the present invention, including a support platform and a removable central portion locked and engaged with the supporting platform.

Figure 3b is a diagram of a heat-treatment apparatus of Figure 3a, with the locking mechanism of the central portion disengaged from the supporting platform.

Figure 3c is a diagram of a heat-treatment apparatus of Figure 3b, illustrating how the central portion can be removed from the supporting platform.

Description

Referring to Figure 1, a diagram of a known heat-treatment apparatus 1 is shown. The heat-treatment apparatus 1 typically comprises a support platform 10, upon which is welded a heavy gauge central core 12. The central core 12 includes a lifting ring 14 to allow the heat-treatment apparatus 1 to be lifted in and out of a heat-treatment furnace and fastening members 16 which protrude from central core 12 and to which the metal components may be fastened to prevent any undue movement during placement in and removal from the heat-treatment furnace. Referring additionally to Figure 2, metal components such as aircraft landing gear components 18a and 18b may be positioned on the support platform 10 and secured via fastening members 16 to the central core.

The support platform 10 comprises a load-bearing metal frame with a mesh plate welded thereon. To minimise the thermal mass of the support platform 10, a lightweight design is employed. However, the central core must be strong enough to withstand the load of the support platform and multiple components positioned thereon (typically 3 to 4 tonnes), and the stresses associated with repeated annealing over its lifetime. Accordingly, the central core comprises a heavy gauge pipe preferably made of steel, which is approximately an order of magnitude heavier than the support platform 10. As will be evident to a person skilled in the art, due to its thickness, the central core has a very large thermal mass capable of holding residual heat for extended periods of time. Figures 3 a, 3b and 3 c show a heat- treatment apparatus 2 in accordance with an embodiment of the present invention. Like the known heat-treatment apparatus 1 shown in figures 1 and 2, the heat-treatment apparatus 2 shown in Figures 3a, 3b and 3c includes a lightweight support platform 20 and a central core 22. However, in this embodiment, the central core 22 is detachable from the support platform 20. Accordingly, during air cooling of heat-treated components, the thermally massive central core 22 of the heat-treatment apparatus can be removed from the vicinity of the cooling components. This means that any residual heat from central core 22 does not affect the uniformity of cooling rates of each component which would otherwise result in physical distortion during the heat- treatment process. Since physical distortion is minimized, pre heat-treated components can be made to more precise dimensions before heat-treatment, without the risk of being written off due to impermissible warping during the cooling process. Further, machining of the much harder post heat-treated components can be kept to a minimum, since the majority of the milling work is done before heat-treat, with only minor refinements being required post heat-treatment.

Returning to Figure 3 a, support platform 20 preferably consists of a load -bearing frame upon which is welded a mesh plate similar in construction to that of the known support platform 10. The support platform 20 further comprises a central bore. The lower portion of the bore is recessed with respect to the upper edge, creating a lip 24 and recess 26 with which the central core 22 can engage.

The central core 22 preferably comprises a hollow heavy gauge metal pipe able to withstand loading from one or more components positioned on the support platform. A lifting ring 28 is incorporated at the top end of the central core 22 to enable the heat- treatment apparatus to be lifted in and out of a furnace and transported around a heat- treatment facility using a crane or other lifting apparatus. In the preferred embodiment, a locking mechanism is incorporated into the apparatus comprising a plurality of locking elements 30 pivotally mounted about the base of the central core 22, each locking element being arranged to engage with the recess 26 in the support platform 20. The locking elements 30 are preferably biased into an unlocked position with respect to the recess 26 allowing default disengagement of the central core 22 from the support platform 20, as illustrated in Figure 3c.

The locking mechanism preferably further comprises an actuator 32 and a lock plunger 34. The actuator 32 is preferably a hydraulic actuator comprising a case 36 and rod 38, the rod being constrained and arranged to slide along the longitudinal axis of the case 36. Alternatively, the actuator may be a mechanical or electrical actuator or any other actuator known in the art.

In an unlocked configuration, as shown in Figure 3c, the lock plunger 34 is retracted into the central core 22 by the actuator 32. Since the locking elements 30 are biased into an unlocked position, the central core 22 can be freely inserted and withdrawn from the central bore of the support platform 20. When the central core 22 is then lowered into an engaging position in relation to the support platform 20 (Figure 3b), the actuator 32 extends lock plunger 34 into the locked position, pivoting the locking elements 30, which engage with the recess 26 underneath the lip 24 of the support platform 20 (Figure 3a). The heat-treatment apparatus can then be lifted and transported complete with support platform 20 and any components positioned thereon.

Preferably, one or more sensors may be incorporated into the heat-treatment apparatus to verify if the central core 22 is attached to the support platform 20. In one embodiment one or more sensors are arranged to determine the position of the locking elements in relation to the recess 26 or lip 24 of the support platform. The sensors may be incorporated into the lip or recess of the support platform. Preferably however, sensors are integrated into one or more of the locking elements. Accordingly, an indication of the successful engagement of each locking element may be obtained and would allow for straightforward connection of each sensor to an indicator outside of the furnace via the central core 22. Additionally or alternatively, one or more sensors may be arranged to determine the position of the lock plunger 34 relative to the central core 22 or the locking elements 30. A sensor could be incorporated into the interior of the central core 22, sensitive to the presence of the lock plunger. Alternatively, the sensor could be integrated into the actuator in order to confirm that the plunger has been actuated into a locked position. A sensor may also be located on the lock plunger itself measuring, for example, its position relative to the locking elements 30. In such embodiments, the sensors may incorporate a simple microswitch or proximity sensor. In practice, any appropriate sensor means known in the art could be used.

An indication as to whether the central core 22 and support platform 20 are attached to one another may then be communicated to an operator by way of a light indication or sound signal, or be communicated to a central display or any other appropriate communication means known in the art.

Preferably, the heat-treatment apparatus further comprises a support guide 40 made from a lightweight thin gauge material arranged to provide some guidance for the central core 22 during insertion and withdrawal from the support platform as well as providing locations at which to attach components to be heat treated, to prevent movement during placement and removal from the heat-treatment furnace.

During heat-treatment, components to be heat-treated are positioned on the support platform, and preferably fastened to the support guide 40. The heat-treatment apparatus 2 may then be lifted by a crane or other lifting apparatus and lowered into a heat treatment furnace. At this point the central core 22 may be disengaged from the support platform 20 by controlling the actuator 32 to retract the lock plunger 34, thus allowing the disengagement of the locking elements 30 from the support platform. The central core 22 may then removed while the support platform 20 and components remain in the furnace. Alternatively, the central core 22 can remain attached to the support platform 20 and in the furnace during heat-treatment. However, preferably the central core 22 is removed so that it is not subject to high temperatures in the furnace which may damage or wear components of the locking mechanism or other features of the central core 22. Once heating in the furnace has been completed, the heat-treated components need to be removed from the furnace for air cooling. If previously removed, the central core 22 is lifted and lowered into engagement with the support platform 20. In this instance, due to the expansion of the hot metal comprising the support platform 20, the bore with which the central core 22 engages will have a reduced radius. The support platform 20 and the central core 22 are manufactured with a tolerance to account for the expansion of the bore. This tolerance also allows for a degree of error in alignment of the central portion 22 with the bore of the support platform 20 during reengagement. Once the central core 22 has been lowered into position with respect to the support platform 20, the actuator 32 extends the locking plunger 34 which pivots the locking elements 30 into engagement with the recess 26 underneath the lip 26.

The heat-treatment apparatus can then be removed from the furnace and placed in a cooling bay or other area for air cooling. Once the apparatus has been placed in the cooling area, the central core 22 can be removed, or left in engagement with the support platform 20. If the central core 22 was not removed during the heating stage however, the core is preferably removed using the method described above in order prevent residual heat from the central core 22 affecting the cooling rate of the heat-treated components. An advantage of the apparatus and method described herein is that there need not be one central core 22 for every single support platform 20. Where several heat-treatment apparatus exist in one heat-treatment facility, a single central core 22 can be used to transport multiple support platforms 20 to and from furnaces and cooling areas. Further, the central core 22 need not be disengaged from the crane or lifting apparatus and could alternatively form part of the lifting means, being used only to transport the support platform from one place to another.

It will be appreciated that other mechanisms could be employed to allow a central core of a heat-treatment apparatus to be disassociated from a platform and the present invention is not limited to the described embodiments.

Although in embodiments described herein landing gear elements are primarily mentioned as the components to be heat-treated, it will be evident to a person skilled in the art that the heat-treatment apparatus of the present invention could used for the heat-treatment of any suitable metal component.




 
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