Forging apparatus

Abstract

A forging apparatus and method is disclosed in which an extrusion punch is held between an upper press and a lower press and propelled towards a billet by a ram to form an extruded shaped component. The extrusion punch has a striking face in which a recess is formed. During the extrusion process, material from the billet enters the recess so as to lock the extrusion punch and the shaped component together. Accordingly the shaped component is not lifted up with the upper press when it is separated from the lower press and so the position of the shaped component after the forging extrusion operation is known accurately and reliably.

Claims

1. A method of forging a shaped component comprising: positioning a billet in a lower press; moving an upper press into engagement with the lower press so as to locate the billet between the upper press and the lower press; striking the billet with a striking surface of an extension punch in a forging direction so as to force the billet into a cavity formed by the upper and lower presses, the cavity defining the shape of the shaped component; and moving the upper press and the lower press away from each other, wherein: the extrusion punch comprises a recess formed in the striking surface into which material from the billet enters as the billet is forced into the cavity, thereby locking the shaped component and the extrusion punch together such that both the shaped component and the extrusion punch remain locked together in the lower press as the upper and lower presses are moved away from each other.

2. A method of forging a shaped component according to claim 1, further comprising: positioning the extrusion punch in the lower press before moving the upper press into engagement with the lower press; and striking the extrusion punch with a separate ram so as to cause the striking of the billet with the extrusion punch.

3. A method of forging a shaped component according to claim 1, wherein: the upper and lower presses move relative to each other in a clamping direction, the clamping direction being perpendicular to the forging direction; and the extrusion punch and shaped component are locked together at the recess so as to restrain relative movement in the clamping direction more than in the forging direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a better understanding of the present disclosure, reference will now be made, by way of non-limitative example only, to the accompanying drawings, in which:

(2) FIG. 1 shows a perspective view of a forging apparatus;

(3) FIG. 2 shows a cross sectional view through a forging apparatus after extrusion of a part;

(4) FIG. 3 shows a perspective view of part of a forging apparatus in accordance with an example of the present disclosure prior to extrusion of a billet;

(5) FIG. 4 shows a cross section through a part of a forging apparatus, including an extrusion punch in accordance with an example of the present disclosure, after an extrusion operation.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) The operation of an example of a forging apparatus 100 has been described above in relation to FIGS. 1 and 2. As explained above, a problem with the arrangement of FIGS. 1 and 2 is that on some occasions the forged component 155 may stick to the upper press 110 as it is moved away from the lower press 120, whereas on other occasions, the forged component 155 may remain in the lower press 120 (for example in the die piece 130 of the lower press 120).

(7) FIG. 3 shows a schematic view of part of a forging apparatus 200 in accordance with an example of the present disclosure. The forging, apparatus 200 has an upper press 210 and a lower press 220. The upper press 210 and the lower press 220 are shown spaced apart, but during use they move together, such that the upper press 210 moves in the direction of arrow B (which may be referred to as the clamping direction) relative to the lower press 220, thereby receiving (which optionally, may include clamping and/or holding) a billet 250.

(8) The forging apparatus 200 also comprises a ram 240 and a separate extrusion punch 260 (which may be referred to simply as a punch 260). The punch 260 is held in a punch holder 270, which may be defined by the lower press upper and/or lower presses 210, 220. In the FIG. 3 example, the punch holder 270 is defined by the lower press 220.

(9) In operation, the ram 240 is propelled towards the punch 260 using a suitable motive force in the direction of arrow A, which may be referred to as the forging direction. As shown in the FIG. 3 example, the direction of arrow A may be perpendicular to the direction of arrow B. The direction of arrow A may be substantially horizontal, for example.

(10) The ram 240 has a striking portion 242 that strikes an impact portion 262 (which may be part of a header portion 264) of the punch 260. This causes the punch 260 to be propelled in the forging direction A towards the billet 250. In turn, this causes the punch 260 (for example an extrusion portion 266 of the punch 260) to strike the billet 250, thereby forcing it from a first cavity 280 in which it is shown in FIG. 3, into a second cavity 290. The second cavity 290 may have the shape of the shaped component that is desired to be output from the forging apparatus 200. This may be any suitable shape, for example an aerofoil shape.

(11) The first and second cavities 280, 290 may be offset from each other in the same direction as the forging direction A, as shown in the FIG. 3 example. Also as illustrated in FIG. 3, the first and/or second cavities may be formed by the upper and lower presses 210, 220, for example when the upper and lower presses 210, 220 are moved together. For example, the upper and lower presses 210, 220 may have respective die portions that conic together to formm the first and/or second cavities 280, 290. Such die portions may be integral parts of the upper and lower presses 210, 220, or may be removable/replaceable parts that are fixed to the respective upper and lower press 210, 220.

(12) The extrusion punch 260 strikes the billet 250 with a striking surface (or striking face) 267. As shown in FIG. 4, the extrusion punch 260 has a recess 268 (which may be referred to as a dimple 268, for example) which is formed in the striking surface 267. The recess 268 may be said to extend from the striking surface along an extrusion axis, for example in the opposite direction to the forging direction A shown in FIGS. 3 and 4. The recess 268 may be said to extend into the extrusion punch 260 from the striking surface 267.

(13) The recess may take any suitable shape, for example it may form a hemisphere (or other part/fraction of a sphere) in (that is, extending into) the striking surface 267. The radius of a sphere forming such a hemisphere or other fraction of a sphere may depend on the component 255 being extruded, for example the size and/or shape of the shaped component 255. By way of example, the radius may be in the range of from 0.5 mm to 10 mm, for example 1 mm to 5 mm, for example 2 mm to 4 mm, for example 2.5 mm to 3 mm where the shaped component 255 is, for example, an aerofoil component (such as a compressor or turbine blade or vane) of a gas turbine engine.

(14) Regardless of the shape of the recess 268, the recess 268 may extend into the extrusion punch 260 from the striking surface 267 to a depth (or distance) shown by the letter in the FIG. 4 example. The depth 1 may be any desired depth, which may depend on the component 255 being extruded, for example the size and/or shape of the shaped component 255. By way of example, the depth 1 may be in the range of from 0.5 mm to 10 mm, for example 1 mm to 5 mm, for example 2 mm to 4 mm, for example 2.5 mm to 3 mm where the shaped component 255 is, for example, an aerofoil component (such as a compressor or turbine blade or vane) of a gas turbine engine.

(15) The example of FIGS. 3 and 4 has just one recess 268 formed in the striking surface 267, but it will be appreciated that the extrusion punch 260 may comprise any number of recesses 268, for example one, two, three, four, five, or more than five recesses 268.

(16) During the forging process (for example during extrusion of the billet 250 to form a shaped component 255), material from the billet (or workpiece) 250 penetrates (for example flows, extrudes or is forced) into the recess 268. The recess 268 may be said to be a void in the extrusion punch 268 into which material from the billet 250 may flow (or fill) during extrusion/forging. As shown by way of example in FIG. 4, this means that the shaped component 255 formed by the extrusion process has an extension 258, which may be referred to as a pip 258, that corresponds in shape to the recess 268 of the punch 260. The pip 258 may be said to be keyed into the recess 268 after extrusion. The shaped component 255 and the punch 260 may be held together (or locked together, or engaged) after the extrusion by the pip 258 of the shaped component interlocking (or engaging) the recess 268 in the punch 260.

(17) After extrusion, the upper and lower presses 210, 220 are moved apart, for example by moving the upper press 210 in the direction of arrow C shown in FIG. 4, which may simply be the opposite direction to the clamping direction B shown in FIG. 3. The directions shown by both arrows B and C may be referred to as the clamping direction, with clamping, being effected by movement of the upper press 210 relative to the lower press 220 in the direction B, and clamping being released by movement in the opposite direction shown by arrow C. Because of the interlocking of the pip 258 and the recess 268, the punch 260 and the shaped part 255 remain locked together even when the upper press 210 and lower press 220 are moved apart. For example, the punch 260 and the shaped part 255 may remain in the lower press 220 (or a die associated with the lower press 220). Accordingly, the position of the shaped part 255 can be reliably and/or accurately known after completion of the extrusion and forging process, for example after the upper and lower presses 210, 220 have been separated. This may allow the shaped part to be located and optionally moved (either by a machine, such as a robot, or by a human) for further processing, which may include removal of the pip 258 and/or other machining/finishing.

(18) As mentioned elsewhere herein, the punch 260 may be held in the forging apparatus 200, for example in the lower press 220, by a punch holder 270. The punch holder 270 may be integral with another part of the forging apparatus (such as the lower press 220) or may be provided as a separate part. The punch holder 270 may restrain (or prevent) the punch 260 from moving in a certain direction, for example in the direction C shown in FIG. 4 in which the upper press 210 is separated from the lower press 220 after the shaped part 255 has been extruded. Because of the engaging pip 258 and recess 268, this may help to ensure that the shaped part 255 is not lifted up with the upper press 210 during separation of the presses 210, 220. However, it will be appreciated that such a punch holder 270 that restrains movement of the punch 260 in the direction C may not be required, and may not be present in all embodiments. For example, the weight of the punch 260 may be sufficient to prevent it (and thus the shaped part 255) from being lifted out of the lower press 220 when the upper and lower presses 210, 220 are separated.

(19) In the example shown in FIGS. 3 and 4, the extrusion punch 260 and the billet 250 are both placed and held between the upper press 210 and the lower press 220 during forging. This means that their relative position, or at least the relative position of their longitudinal axes, is defined by the same piece of apparatus (i.e. the presses 210, 220), and thus cannot vary between forging operations. This arrangement ensures that the punch 260 always strikes the billet 250 in the same direction and at the same position. As such, regardless of any variability in alignment of the punch 260 and the ram 240 (and thus of the billet 250 and the ram 240) no unknown or variable force or bending moment is passed into the punch 260, and so it is not susceptible to breakage.

(20) This means that even if the precise position of upper and lower presses 210, 220 varies slightly between forging operations and/or over time, for example due to the extremely high loads involved, the punch 260, and thus the portion 266 of the punch 260 that strikes the billet 250, is always axially aligned with the billet 250. Thus, even if the ram 240 strikes the punch 260 along a skewed or offset path, the punch 260 still provides a forging (or extrusion) force to the billet 250 that is aligned with the billet 250, for example collinear with the longitudinal axis of the billet 250.

(21) This arrangement in which the ram 240 and the extrusion punch 260 are separate may help to prevent damage to the components of the forging apparatus 200 because no unknown or unwanted force or bending moment is passed through the interface between the relatively narrow extrusion portion 266 of the punch 260 and the rest of the punch 260. Any unwanted force or bending moment that results from an unwanted offset of the ram 240, punch 260 and billet 250 passes through the much bulkier and stronger parts of the ram 240 and punch 260 which are not subject to the same dimensional constraints, and thus can be engineered to resist such unwanted forces/bending moments.

(22) However, whilst the example of FIGS. 3 and 4 is shown as having a separate ram 240 and extrusion punch 260, it will be appreciated that other examples in accordance with the invention may have a combined ram and punch. For example, the billet 250 may be directly struck by an extrusion punch that is propelled by a motive force (for example an external motive force) towards the billet 250 in the extrusion direction A to form the shaped component 255. Such an extrusion punch may, for example, be substantially as described in relation to FIGS. 1 and 2, but may be provided with a striking surface 267 and recess 268, for example as described above in relation to FIGS. 3 and 4. As such, an extrusion punch according to the invention may itself be propelled towards the billet 250 in use (as in FIGS. 1 and 2, for example), or a separate ram 240 may be provided to strike the extrusion punch (as in FIGS. 3 and 4, for example).

(23) It will be appreciated that the forging apparatus 200 described and claimed herein may be a part of a larger apparatus and/or process. For example, the shaped component 255 generated after the billet 250 has been forged by being forced into the second cavity (or die) 290 may required further processing, such as finishing and/or further shaping in order to become a finished part. By way of further example, the billet 250 may be heated before being transferred to the first cavity 280. The various processes may be automated, including the transportation of the billet 250 and/or shaped components between the various processes.

(24) Any component and/or feature described herein may be combined with any other compatible component and/or feature. Furthermore, it will be appreciated that various alternative and/or complimentary arrangements and/or components not explicitly described herein are in accordance with the invention.