Hot Forging Process and Mould for Carrying Out Said Process

Abstract

A mould for hot forging includes a first half-mould and a second half-mould. The first and second half-moulds each include a mould holder having a recess and a die provided with an impression. The die is combined with the mould holder at the recess. At least one of the first half-mould and the second half-mould is provided with at least one feeding channel for a lubricating-cooling liquid, extending from an outer wall of the mould holder to the recess of the mould holder, and with a plurality of distribution channels for the lubricating-cooling liquid. At least one quota of the plurality of distribution channels includes distribution channels extending from a wall of the die facing the recess, to the impression. The at least one feeding channel and the distribution channels face at least one gap formed between the mould holder and the respective die at the recess.

Claims

1. A mould for hot forging, comprising: a first half-mould and a second half-mould, each comprising a mould holder having a recess, and a die provided with an impression, wherein the die is combined with the mould holder at the recess, characterised in that at least one of said first half-mould and said second half-mould is provided with at least one feeding channel to feed a lubricating-cooling liquid, substantially extended from an outer wall of the mould holder to the recess of the mould holder, and with a plurality of distribution channels for the lubricating-cooling liquid, wherein at least one quota of said plurality of distribution channels comprises distribution channels, which extend from a wall of the die facing said recess, to said impression, wherein said at least one feeding channel and the distribution channels of said plurality of distribution channels face at least one gap formed between the mould holder and the respective die at said recess.

2. The mould according to claim 1, wherein said plurality of distribution channels comprises distribution channels parallel to each other.

3. The mould according to claim 1, wherein said plurality of distribution channels comprises at least one distribution channel substantially perpendicular to said feeding channel and/or said gap.

4. The mould according to claim 1, wherein said plurality of distribution channels comprises at least one distribution channel inclined with respect to said feeding channel and/or said gap, preferably by an angle of between about 5° and about 85°.

5. The mould according to claim 4, comprising a plurality of inclined distribution channels, wherein at least one quota of said plurality of inclined distribution channels comprises inclined distribution channels, which are substantially converging toward said impression.

6. The mould according to claim 1, wherein said plurality of distribution channels comprises at least one non-linear distribution channel.

7. The mould according to claim 1, wherein said at least one quota of said plurality of distribution channels comprises at least one non-linear distribution channel comprising a first length substantially perpendicular to said feeding channel and/or said gap, and/or a second length substantially perpendicular to said impression.

8. The mould according to claim 1, wherein said distribution channels have a diameter lower than about 0.4 mm, preferably lower than about 0.3 mm, more preferably equal to or lower than about 0.2 mm.

9. The mould according to claim 1, wherein at least one second quota of said plurality of distribution channels comprises distribution channels that have respective openings facing a wall of said die containing said impression in portions of said wall, which are outside said impression.

10. The mould according to claim 1, wherein said mould holder and/or said die comprise, at said recess and, respectively, at said wall facing said recess, at least one step.

11. The mould according to claim 1, wherein both said first half-mould and said second half-mould are provided with said at least one feeding channel for the lubricating-cooling liquid, with said plurality of distribution channels for the lubricating-cooling liquid and with said at least one gap.

12. A hot forging process comprising the steps of: a) providing a mould according to any one of the preceding claims; b) feeding, under pressure, a lubricating-cooling liquid into said at least one feeding channel; c) feeding a preheated billet into said first half-mould or said second half-mould; d) closing said mould by applying a pre-set pressure to said first half-mould and/or to said second half-mould; e) cooling said mould; f) opening said mould; g) ejecting a forged semi-finished product obtained from said billet.

13. The process according to claim 12, wherein during the process, said distribution channels are substantially and constantly filled with said lubricating-cooling liquid.

14. The process according to claim 12, wherein said step g) of ejecting said semi-finished product is carried out by increasing the pressure of said lubricating-cooling liquid.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0073] Further characteristics and advantages of the invention will become better apparent from the following detailed description of some preferred, but not exclusive, embodiments depicted by way of non-limiting example with the support of the accompanying drawings, wherein:

[0074] FIG. 1 shows a perspective view of a half-mould of a mould for hot forging, comprising a mould holder and a die combined with the mould holder, in accordance with the present invention;

[0075] FIG. 2 shows a perspective cross-sectional view of the half-mould of FIG. 1, with respective enlarged detail;

[0076] FIG. 3 shows a perspective view of the aforesaid mould holder of the half-mould of FIG. 1;

[0077] FIG. 4 shows a cross-sectional view of the mould holder of FIG. 3;

[0078] FIG. 5 shows a perspective cross-sectional view of the die of the half-mould of FIG. 1, with respective enlarged detail, in accordance with an implementation variant of the invention;

[0079] FIG. 6 shows a perspective cross-sectional view of the die of the half-mould of FIG. 1, with respective enlarged detail, in accordance with a further implementation variant of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0080] With reference to FIGS. 1-4, 1 generally denotes a half-mould of a mould for hot forging, according to the present invention.

[0081] The half-mould 1 can be a so-called lower half-mould or a so-called upper half-mould of the aforesaid mould which, therefore, may optionally comprise two half-moulds substantially similar as regards the structural and functional characteristics in accordance with the present invention.

[0082] In detail, the half-mould 1 comprises a mould holder 2 having a recess 3, and a die 4 provided with an impression 5, wherein the die 4 is combined with the mould holder 2 at the recess 3.

[0083] In practice, the impression 5 is also a recess that corresponds to the negative of the geometry, or rather of part of the final geometry, of the semi-finished product to be achieved.

[0084] In accordance with the invention, the half-mould 1 is provided with a feeding channel 6 for a lubricating-cooling liquid, substantially extending from an outer wall 7 of the mould holder 2 to the recess 3 of the mould holder 2 and with a plurality of distribution channels for the lubricating-cooling liquid, each one denoted by 8, wherein a quota of the aforesaid plurality of distribution channels consists of distribution channels extending from a wall 9 of the die 4 facing the recess 3, to the impression 5.

[0085] In practice, a part of the distribution channels 8, i.e. the distribution channels of the aforesaid quota, have openings 8a facing the impression 5, while another part of the distribution channels 8, basically the distribution channels of a second quota of the aforesaid plurality of distribution channels, have openings 8b facing a wall 10 of the die 4 in which the impression 5 is arranged, at portions of the wall 10 outside the impression 5.

[0086] Moreover, in accordance with the invention, the feeding channel 6 and the distribution channels 8 face a gap 11 formed between the mould holder 2 and the die 4 at the recess 3.

[0087] Basically, in accordance with the above and according to the present invention, during the use of the half-mould 1, the lubricating-cooling liquid coming from the feeding channel 6 collects in the gap 11 from which it then reaches the forging surface of the half-mould 1, at the wall 10 of the die, through the distribution channels 8 which distribute the lubricating-cooling liquid substantially uniformly and homogeneously on the same forging surface, thanks to the surface tension of the lubricating-cooling liquid.

[0088] In accordance with the invention, it should be added that the number of distribution channels as well as the respective positions, the respective dimensions, the respective orientations and inclinations may vary, as required, also in a same die, as well as it is possible to provide for more than one feeding channel in the same mould holder and more gaps in the same half-mould. It should be noted that the homogeneity of the lubricating-cooling, i.e. a substantially homogeneous flow of the lubricating-cooling liquid on the surface of interest, is favoured by distribution channels with a direction as perpendicular as possible to the surface to be lubricated.

[0089] In this regard, the distribution channels have a diameter preferably lower than about 0.4 mm, more preferably lower than about 0.3 mm, even more preferably equal to or lower than about 0.2 mm, the aforesaid die being preferably at least partially implemented with additive production techniques and preferably being integrally implemented with additive production techniques, without post-processing.

[0090] As is known, additive production or additive manufacturing or additive process or layer manufacturing (Additive Manufacturing o AM) is an industrial process used to manufacture objects by starting from computerised 3D models, adding one layer on top of the other (3D printing), as opposed to the so-called traditional subtractive production methods which use milling machines or lathes and which start from a block of material from which chips or portions are mechanically removed.

[0091] The additive production allows to achieve complex geometries that cannot be achieved with the aforesaid traditional methods, without generally increasing the costs to be incurred for the production of the final product which is the object of the hot-forging process.

[0092] Again in this regard, in the example of the aforesaid figures, distribution channels 8 are shown parallel to each other and perpendicular to the feeding channel 6, and therefore perpendicular to the gap 11.

[0093] It should be noted that in the example of the aforesaid figures, all the distribution channels 8, both those having the opening 8a facing the impression 5 and those having the opening 8b facing outside the impression 5, are parallel to each other and substantially perpendicular to the feeding channel 6, therefore perpendicular to the gap 11, the possibility of providing, in addition to or in place of, the aforesaid distribution channels parallel to each other being however not excluded, one or more distribution channels inclined with respect to the feeding channel, therefore inclined with respect to the gap, by an angle between about 5° and about 85°, and/or one or more non-linear distribution channels, as will better appear hereinafter.

[0094] It should also be added that, in order to make the gap 11, the die 4 is provided, at the aforesaid wall 9, with a step 12, the possibility of providing for such a step also, or only, at the recess 3 of the mould holder 2 being however not excluded, as well as it is possible to provide for steps capable of making more than one gap of the aforesaid type and as well as it is possible to provide for other means capable of making at least one gap of the aforesaid type, e.g. spacers.

[0095] In the example of the aforesaid figures, the half-mould 1 is also shown with holes 13 adapted to be engaged by the columns of a press provided for carrying out hot forging with the present mould.

[0096] Finally, it should be added that the mould holder 2 preferably consists of a forged steel block which can be used to implement several pieces, i.e. several semi-finished products, and which can be provided with a plurality of inner channels for cooling circuits, of a known type, in the examples of the figures not depicted.

[0097] FIG. 5 shows the die of the half-mould of FIG. 1 in accordance with an implementation variant of the invention, in which parts structurally and functionally corresponding to those of the die 4 described above retain the same reference numerals of FIGS. 1-4.

[0098] In detail, the example of FIG. 5 shows a die 104 which is entirely similar to the die 4, the description of which is set forth above, except for the fact that it comprises distribution channels 108 for the lubricating-cooling liquid, which are inclined, not parallel to each other and converging toward an impression 105, as mentioned above.

[0099] In the example of FIG. 5, a step 12 of the die 104 is also depicted, which is adapted to form a gap with the recess of the respective mould holder which, in this case, may be a mould holder entirely similar to the mould holder 2 referred above, the description of which is provided above.

[0100] In the example of FIG. 5, moreover, the die 104 is provided only with distribution channels 108 which have the respective openings 108a facing the impression 105.

[0101] FIG. 6 shows the die of the half-mould of FIG. 1 in accordance with a further implementation variant of the invention, in which parts structurally and functionally corresponding to those of the die 4 described above, retain the same reference numerals of FIGS. 1-4.

[0102] In detail, the example of FIG. 6 shows a die 204 entirely similar to the die 4, the description of which is provided above, except for the fact that it comprises non-linear distribution channels 208 for the lubricating-cooling liquid, as mentioned above.

[0103] In detail, the distribution channels 208 comprise a first length 208a substantially perpendicular to a gap which the die 204 forms with a recess of the respective mould holder, in the example of FIG. 6 not shown, and a second length 208b substantially perpendicular to an impression 205 provided in the die 204.

[0104] In the example of FIG. 6, a step 12 of the die 204 is also depicted, which is adapted to form the aforesaid gap with the recess of the mould holder which, in this case, may be a mould holder entirely similar to the mould holder 2 referred above, the description of which is provided above.

[0105] Moreover, in the example of FIG. 6, the die 204 is provided only with distribution channels 208 which have the respective opening 108a facing the impression 205.

[0106] A die in accordance with the example of FIG. 6 makes the most of the potentials of additive production, since it allows to direct the flow of the lubricating-cooling liquid to a direction substantially perpendicular both to its inlet in the distribution channels and to its outlet from the distribution channels.

[0107] In accordance with the foregoing, a hot forging process according to the present invention is now described, which comprises the steps of: [0108] a) providing a mould for hot forging of the type described above, i.e. comprising a first half-mould and a second half-mould in which at least one half-mould 1 between the first half-mould and the second half-mould comprises a mould holder 2 having a recess 3, and a die 4, 104, 204 provided with an impression 5, 105, 205, in which the die 4, 104, 204 is combined with the mould holder 2 at the recess 3, wherein the half-mould 1 is provided with a feeding channel 6 for a lubricating-cooling liquid, which is substantially extending from an outer wall 7 of the mould holder 2 to the recess 3 of the mould holder 2, and with a plurality of distribution channels 8, 108, 208 for the lubricating-cooling liquid, wherein at least one quota of the distribution channels 8, 108, 208 comprises distribution channels extending from a wall 9 of the die 4, 104, 204 facing the recess 3, to the impression 5, 105, 205, wherein the feeding channel 6 and the distribution channels 8, 108, 208 face a gap 11 formed between the mould holder 2 and the die 4, 104, 204 at the recess 3 of the mould holder 2; [0109] b) feeding, under pressure, the lubricating-cooling liquid into the feeding channel 6; [0110] c) feeding a preheated billet into the first half-mould or the second half-mould of the mould; [0111] d) closing the mould by applying a pre-set pressure to the first half-mould and/or to the second half-mould; [0112] e) cooling the mould; [0113] f) opening the mould; [0114] g) ejecting a forged semi-finished product achieved from the aforesaid billet.

[0115] Advantageously, in accordance with the invention, the aforesaid step b) in which the lubricating-cooling liquid is fed into the feeding channel 6, allows to lubricate, in a substantially homogeneous manner, the forging surface of the half-mould 1, considering also that, during the present process, the aforesaid distribution channels are preferably constantly crossed by the lubricating-cooling liquid, i.e. they are preferably substantially always full of lubricating-cooling liquid during the process.

[0116] This way, having defined, during the die designing step, the number of channels for distributing the lubricating-cooling liquid, the position of the distribution channels, their diameter, their orientation and their inclination, it is possible to have the pressure applied to the lubricating-cooling liquid as the only process parameter.

[0117] Advantageously, moreover, if necessary, the lubricating-cooling liquid may also be used to eject the semi-finished product achieved by forging. In this regard, in the present process, the aforesaid step g) may be carried out by increasing the pressure of the lubricating-cooling liquid. In fact, due to the presence of the semi-finished product inside the mould which blocks the distribution channels of the die, the lubricating-cooling liquid may be compressed inside the same distribution channels until the semi-finished product is detached, all controlled by an automated control unit.

[0118] Furthermore, the use of the lubricating-cooling liquid to eject the semi-finished product advantageously allows to make moulds without the classic ejectors, thus reducing the complexity of the mould holders.

[0119] As regards the lubricating-cooling liquid, it should be stated that it is possible to use any lubricating-cooling liquid of known type.

[0120] The advantages of the present invention, which are evident in the above description, can be summarised by pointing out that a mould for hot forging has been provided in which the traditional spray lubrication system is replaced by a diffusion system from the inside of the mould, or rather of the half-mould, of the lubricating-cooling liquid, which substantially entails: [0121] for the lubrication, only using the lubricating-cooling liquid necessary to form a thin film on the forging surface of a half-mould, without waste; [0122] reducing the lubricating-cooling liquid dispersed in the mould and in the entire equipment comprising the mould, resulting in less frequent cleaning and maintenance operations, thus lengthening the operating useful life of the mould and the respective equipment; [0123] dispersing the lubricating-cooling liquid in the surrounding environment is avoided and, therefore, the need to resort to constantly active suction systems is avoided, resulting in reduced energy consumption; [0124] during the die designing step, the distribution of the lubricating-cooling liquid reaching the forging surface can be effectively envisaged, by defining the number, position, orientation, inclination and diameter of the channels for distributing the lubricating-cooling liquid, therefore being able to control effectively, during the process, the distribution of the lubricating-cooling liquid reaching the forging surface; [0125] during the process, the lubrication step becomes simpler to manage, since the only parameter to be managed consists of the pressure applied to the lubricating-cooling liquid as time varies, a pressure which can therefore be advantageously controlled by a PLC system.

[0126] In the embodiments depicted and described, in order to satisfy contingent and specific requirements, a person skilled in the art may make numerous variations and modifications to the present invention, all of which are within the scope of protection of the invention as defined by the following claims.