EP2480358B1 - Method for producing a composite part - Google Patents

Description

The invention relates to the production of a composite component.

From the Japanese Patent Publication 2000-144212 discloses a method in which a cam disk is formed from a green compact and sintered. A coupling element is built into the green compact before sintering and is also sintered in order to connect it to the sintered part.

From the JP 1996-134509 A a production method of green compacts for multilayer sintered parts is known.

From the DE 199 44 522 A1 discloses a manufacturing method for a sintered composite machine component having an inner part and an outer part.

From the U.S. 5,667,536 A a method for manufacturing a chip is known.

The object of the present invention is to provide a method by means of which a composite component can be produced quickly and inexpensively.

The object is achieved according to the invention by means of a method according to claim 1, a press according to claim 4 and a composite green compact according to claim 5.

A method for producing a composite component is proposed, the composite component having at least one powder metallurgical part pressed from a powdery substance and at least one solid part, the powdery substance being pressed into a powder metallurgical part within a working space of a tool of a press and in the same operation , in particular in the same working stroke of the press, the solid part is at least partially fed to the work area, so that the composite component is produced within one work step. A powdery substance is to be understood in particular as a powdered metal. Furthermore, a solid part can have a metal or ceramic material. For example, a solid part can have a cast, drawn, sintered, rolled, forged and / or extruded - in particular extruded - material. One operation of the press comprises a working stroke and a return stroke, the press collapsing during the working stroke and opening again on the return stroke. Possibly The operation can also include a downtime, with the press or the tool of the press remaining in one position for a defined time between the working stroke and the return stroke.

According to the invention it is provided that in a first step of the operation the solid part is fed to the powdery substance in the work space and in a second step the powdery substance is pressed into a powder-metallurgical part or a green compact. In a further embodiment it is provided that in a first step of the work step the powdery substance is pressed into a green compact in the work area and in a second step the solid part is fed to the green compact in the work area. In another embodiment according to the invention it is provided that the solid part is fed to the working space while the powdery substance is pressed into a green compact.

In the following, the term green compact is used for an unsintered, powder-metallurgical part pressed from a powdery substance. A powder metallurgical part is generally understood to mean a green compact, a sintered compact and / or a sintered compact.

For example, the solid part and the powdery substance can have the same alloy. In further refinements, it is provided that the powdery substance and the solid part have different alloys. In particular, it is provided that the powdery substance comprises a metal powder and the solid part comprises a non-metallic material, for example ceramic. In a further embodiment, the powdery substance has a ceramic powder and the solid part has a ceramic or non-ceramic material. Thus, a powder metallurgical part can also be understood to mean a component that has a non-metallic material, in particular does not include a metallic material. It is also provided in one embodiment that the solid part and the powdery substance have different metal or ceramic alloys. Alloys can be understood here as metal alloys or ceramic mixtures as well as pure metals or ceramics.

According to the invention, it is provided that the solid part is transferred into the working space in such a way that the solid part protrudes from a surface of the green part or the powder-metallurgical part after the operation. In a further embodiment, the solid part ends with at least one surface of the powder-metallurgical part. In particular, it is provided in one embodiment that the Solid part protrudes with an oversize from a surface of the powder metallurgical part. In a further embodiment it is provided that the solid part ends with an undersize below a surface of the powder metallurgical part. Oversize or undersize of about 0.001 millimeters to about 15 millimeters, in a further embodiment up to about 20 centimeters are provided.

In another variant, the solid part is surface-treated, preferably before it is placed in the press. In particular, a roughness is increased in at least a defined part of the surface. The solid part preferably has an average roughness depth of Rz = 1 μm to Rz = 63 μm over at least part of its surface. A roughness is to be understood as a third to fifth order deviation in shape for surfaces in accordance with DIN 4760. At least part of the surface of the solid part is particularly preferably oxidized or coated with a conversion layer, for example burnished or phosphated.

In a further embodiment, it is provided that a metal oxide layer is produced on the solid, in particular metal, part by means of a steam treatment. This is carried out in particular at temperatures of approximately 500 ° C to 570 ° C. The steam treatment of the solid part is preferably carried out for at least 10 minutes, preferably at least 30 minutes. Furthermore, an oxide layer thickness of at least 2 μm is preferably produced. This has the advantage that the powder particles of the powdery substance can better grip the surface of the solid part. Furthermore, an oxide layer has the advantage that it is reduced again during a sintering process and, in particular, improved sintering between powder particles and solid part can take place. In a further embodiment, the surface is treated mechanically, for example roughened by grinding or roughing. A variant also provides that the surface is smoothed, for example polished.

The composite component is sintered and / or pre-sintered, for example after demolding from the press, in order to carry out further processing steps if necessary. In a further embodiment it is provided that the composite component is sinter-forged.

A further idea of the invention comprises a press for pressing and joining a composite component, the press having a working space and at least one press ram and at least one joining ram. According to the invention, the press additionally at least one transfer stamp. According to the invention, a powdery substance is supplied to the work space, a green compact made of the powdery substance being able to be pressed in the work space by means of the press ram. Furthermore, a solid part can be transferred into the working area by means of the joining punch and the transfer punch. Furthermore, the solid part is at least partially fed to the powdery substance or the green compact, with the transfer die in the working space being able to provide a joining space into which the solid part can be transferred with the joining die. In particular, the joining space is at least partially defined by the powdery substance introduced into the working space.

The press has a control device, the control device controlling a transfer of the solid part into the work space. A computer program product is implemented on the control device that controls the transfer stamp in such a way that it holds a joining space in the working space that is at least partially filled with a powdery substance and into which a solid part is transferred by means of the joining stamp and the transfer stamp. The powdery substance that fills the joining space preferably at least partially adjoins the joining punch and thus the joining space. In particular, it is provided that when the solid part is transferred into the joining space, the powdery substance at least partially fills the joining space, which is preferably not filled by the solid part. In a further embodiment, which is not part of the invention, it is provided that the solid part is introduced into the powdery substance by means of the joining punch, the solid part displacing the powdery substance when it is immersed in the powdery substance. In this embodiment, a transfer die to keep the joining space free is not necessary.

Another concept of the invention comprises a use of the above-mentioned press for an above-mentioned method.

The disclosure comprises a computer program product for a press with a tool, the tool having a work space and at least one press die and at least one joining die, a method being implemented in the computer program product with which the joining die is controlled in this way is that this transfers a solid part into a working space that is at least partially filled with a powdery substance. In a first embodiment it is provided that a transfer stamp is controlled in such a way that it is in the working space holds a joining space, which is at least partially filled with a powdery substance, in particular to be pressed, and into which a solid part is transferred by means of the joining punch. In particular, it is provided in one embodiment that after a transfer of the solid part into the joining space, the press ram is actuated so that the powdery substance is pressed into a green compact. In a further embodiment, it is provided that, before the solid part is transferred into the joining space, the press ram is actuated so that the powdery substance is pressed into a green compact. The computer program product preferably controls a pressing process and a joining process at the same time. In this context, the term “control” is understood to mean both the activation by means of a controller without feedback and the regulation by means of a closed-loop control with feedback. The joining punch and / or the transfer punch is preferably moved by means of a route control or a route control. Furthermore, it is provided in one embodiment that the press ram is controlled in such a way that it applies a predetermined force to the powdery substance or performs a predetermined work on the powdery substance. The specifications are determined, for example, by a user or fitter of the press, preferably as a function of properties that the green compact or the composite green compact should have. In a further embodiment, a ram is moved by means of a route control or route regulation.

A further concept of the invention comprises a composite component produced by the method having at least one green compact pressed from a powdery substance and at least one solid part. In one embodiment it is provided that the powdery substance and the solid part have the same alloy. According to the invention it is provided that the powder metallurgical part has a shrinkage during sintering which is greater than or equal to a shrinkage of the solid part, the solid part generally not shrinking during sintering. Furthermore, one embodiment provides that shrinkage of the powder-metallurgical part during sintering is greater than that of the solid part, preferably such that the powder-metallurgical part enters into a press fit with the solid part. It is also preferred that the solid part enters into a material connection with the powder-metallurgical part during sintering and is preferably sintered at the interfaces. According to the invention, the solid part has a thread via which the solid part and the metallurgical part enter into a form-fitting connection. In an embodiment that is not part of the invention, the solid part can be designed with an external thread, thus a fully sintered Component from a composite component, for example, without a further processing step a thread. In further refinements, different geometries are provided for the solid part. For example, the solid part can be designed as a sheet metal, pin, bolt, pin, shaft, nut, threaded rod, feather key and / or bearing. Any geometry that can be fed to the powdery substance or the powder-metallurgical part is preferably suitable. It is also provided in one embodiment that several solid parts are arranged in a composite component. Another variant provides that at least one solid part is arranged in more than one powder-metallurgical part and in particular connects these.

It can be seen from the configurations given above that a composite component produced and sintered according to the invention has both the advantages of a solid part, which in particular can be an inexpensive purchased part, and the advantages of a sintered part. If the composite component is manufactured using the method described above, the manufacturing costs are significantly lower and the bond between the solid part and the powder-metallurgical part is significantly more reliable than in the case of methods known from the prior art, especially in the case of subsequently introduced solid parts.

Fig. 1

ein schematischer Ablauf eines Einbringens eines Massivteils in einen pulverförmigen Stoff während einer Verdichtung;

Fig. 2

ein schematischer Ablauf eines Einbringens eines Massivteils in einen pulverförmigen Stoff nach einer Verdichtung des pulverförmigen Stoffes;

Fig. 3

Schliffbild eines eingesetzten Gewindestiftes;

Fig. 4

Schliffbild eines eingesetzten Stahlstiftes; und

Fig. 5

Ausführungsbeispiele von Verbundbauteilen.

Further advantageous configurations emerge from the following drawings. However, the developments shown there are not to be interpreted restrictively; rather, the features described there can be combined with one another and with the features described above to form further configurations. Furthermore, it should be pointed out that the reference symbols given in the description of the figures do not restrict the scope of protection of the present invention, but merely refer to the exemplary embodiments shown in the figures. Identical parts or parts with the same function have the same reference symbols below. Show it:

Fig. 1

a schematic sequence of introducing a solid part into a powdery substance during compaction;

Fig. 2

a schematic sequence of the introduction of a solid part into a powdery substance after a compression of the powdery substance;

Fig. 3

Micrograph of an inserted grub screw;

Fig. 4

Micrograph of an inserted steel pin; and

Fig. 5

Exemplary embodiments of composite components.

Fig. 1 shows a sequence of process steps A to D, in which a solid part 1 is connected to a powder-metallurgical part 2 in order to form a composite component 3. In step A, a solid part 1 is inserted into the tool 5 of a press via an automatic feeder 4. The press is simplified here, represented by the tool 5 for the sake of clarity. Furthermore, a powdery substance 7 is poured into a working space 6 of the tool 5. A transfer stamp 8.1 keeps a joining space 9 free in the working space 6, which is at least partially filled with the powdery substance 7.

In step B, a first press ram 10.1 and a second press ram 10.2 are closed so that the powdery substance 7 is compressed. Furthermore, the solid part 1 is simultaneously transferred into the powdery substance 7 by means of the transfer stamp 8.1 and the joining stamp 8.2. Pressure is exerted on the solid part 1 by the transfer die 8.1 and the joining die 8.2 in order to hold the solid part 1. The solid part 1 is preferably not plastically deformed by the pressure, further preferably the solid part is elastically deformed by less than 0.5% of its expansion in the direction of force by the pressure.

In step C of the Fig. 1 the transfer of the solid part 1 and the compaction of the powdery substance 7 to form a non-sintered powder-metallurgical part 2 - hereinafter referred to as green compact 2 - is completed. In particular, the transfer and / or the compression of the powdery material is controlled or regulated via a route control or regulation.

In step D of the Fig. 1 the finished composite component 3 is removed from the mold. Processing or sintering of the composite component can now take place in further steps. In particular, it is provided that the sintered composite component is at least partially calibrated.

In a further embodiment, it is provided that in step B, that is, when the solid part 1 is transferred into the powdery substance 7, no or only an insignificant compression of the powdery substance 7 is carried out. An insignificant compression is to be understood as a compression which is below about 80%, preferably below about 60% of the targeted density of the green compact 2.

Fig. 2 shows a further variant for the production of a composite green body 3, in which in a first step E a solid part 1 is fed to a press 5 and a powdery substance 7 is filled into the working space 6.

In a second step F, the powdery substance 7 is compacted to form a green compact 2; in particular, the substance 7 is compacted to about 60% to 100% of the targeted density of the green compact 2 in step F. Furthermore, the solid part 1 is transferred into the green compact 2, the compression of the green compact 2 being interrupted in one embodiment. In a further embodiment, the solid part 1 is supplied during a compression of the green compact 2 or after a desired compression of the green compact 2.

In step G, a final compression of the green compact 2 is carried out if this has not yet been carried out in step F. Furthermore, a transfer of the solid part 1 into the green compact 2 is ended. The finished composite component 3 is removed from the mold in the last step H by, for example, the transfer stamp 8.1 pushing the composite component out of the working space 6. In a further embodiment it is provided that the ram 10.1 transports the composite component out of the working space 6. In a further variant it is provided that a die 11 delimiting the working space 6 is displaced in such a way that the composite component is exposed and can be removed from the press.

Fig. 3 shows an etched micrograph of a sintered composite component 3 having a burnished threaded pin 12, around which a powder-metallurgical part 2 was pressed. The threaded pin 12 was not blasted bright before joining. It can be seen that the powdery substance 7 penetrated into the thread turns of the threaded pin 12 as a result of the pressing process of the green compact and thus a dimensionally stable connection was established between the threaded pin and the powder-metallurgical part.

Fig. 4 shows a micrograph of a steel pin 13 pressed into a powder metallurgical part 2. The composite component was sintered at 1250 ° Celsius. Sintering across grains cannot be recognized, but this type of joint means that there is excellent mechanical contact between the powder-metallurgical part 2 and the steel pin 13.

Fig. 5 shows various schematic, non-restrictive configurations of a composite component 3. In particular, the geometries of the solid part 1 and / or the powder-metallurgical part 2 can differ from the configurations shown here. The respective upper sectional view of the respective configuration is a section through a diameter D of the composite component 3.

Design I shows the solid part 1 protruding on one side over the powder-metallurgical part 2. In embodiment J it can be seen that the solid part 1 projects beyond the powder-metallurgical part 2 on both sides. The embodiment K shows a composite component 3 with three solid parts 1, whereby the embodiment shown here is not to be interpreted restrictively, rather it is provided in further variants that two solid parts 1 are provided. Another embodiment provides more than three solid parts 1 in the composite component 3.

Embodiment L shows a threaded pin 12 which has been pressed into a powder metallurgical part 2. A nut 14 introduced into the powder metallurgical part 2 emerges from variant M. In particular, it is provided that any geometry of the solid part with an internal thread is introduced into the powder-metallurgical part. A commercially available nut, for example a hexagon nut, is preferably introduced into the powder-metallurgical part.

Embodiment N shows a stamped part 15 pressed into the powder metallurgical part 2. In a further variant, it is provided that a cast, forged or sintered solid part 1 is introduced into the powder metallurgical part 2.

In version O, a composite component 3 can be seen in which a solid part 1 protrudes on a surface 16 orthogonally to a pressing direction of the green compact 2. Another variant P provides that two powder metallurgical parts 2 are pressed in one operation and connected by means of at least one solid part 1.

Variant Q shows a composite component 3, the solid part 1 of which does not completely penetrate the powder-metallurgical part 2. This can be achieved in particular if the solid part 1 is transferred into the powdery substance without a joining space being kept free. The solid part 1 thus displaces the powdery substance when it is joined. In an embodiment not shown here, the solid part 1 is at least in one end area 17, which is inserted into the powdery substance, is at least partially tapered in order to promote a displacement of the powdery substance.

It is provided in particular that the exemplary configurations of the composite component 3 of Fig. 5 can be combined with one another and / or with the configurations described above.

Claims (10)

1. Method for producing a composite part (3), the composite part (3) comprising at least one powder-metallurgical part (2) compacted from a powdery material (7) and at least one solid part (1), wherein within a working chamber (6) of a tool (5) of a press the powdery material (7) is pressed to a powder-metallurgical part (2) and in the same working cycle of the press (20) the solid part (1) is at least partly supplied to the working chamber (6), so that the composite part (3) is produced within one working cycle, characterized in that

   - the solid part (1) is inserted into the tool (5) of the press (1) via an automatic feed (4),

   - the powdery material (7) is filled into the working space (6) of the tool (5), while a transfer punch (8.1) keeps free a joining space (9) in the working space (6), wherein a circumference of the joining space (9) is at least partially filled with the powdery material, and the joining punch (8.2) and the transfer die (8.1) jointly transfer the solid part (1) into the joining space (9),

   - in a first step of the working cycle, the solid part (1) is fed to the powdery material (7) in the working chamber (6) and, in a second step, the powdery material (7) is compacted to form a powder-metallurgical part (2), or

   - the solid part (1) is fed to the working chamber (6) while the powdery material (7) is compacted to a powder-metallurgical part (2), wherein a first press punch (10.1) and a second press punch (10.2) are actuated and the powdery material (7) is compacted, while at the same time the solid part (1) is transferred into the joining space (9) into the powdery material (7), wherein the transfer punch (8.1) and the joining punch (8.2) holding the solid part (1) while exerting pressure on it,

   - the solid part (1) is transferred into the working space (6) in such a way that the solid part (1) protrudes from a surface (16) of the powder metallurgical part (2) after the working cycle.
2. Method according to claim 1, wherein the solid part is surface-treated before being introduced into the press.
3. Method according to any of the preceding claims, wherein the composite part (3) is sintered.
4. Press (20) for compacting and joining a composite part (3), wherein the press (20) comprises at least one tool (5) by means of which a working chamber (6) can be created, further at least a first pressing punch (10.1) and at a second pressing punch (10.2) and at least a joining punch (8.2), wherein a green compact (2) is compactable from a powdery material (7) in the working space (6) by means of the first and second pressing punches (10.1, 10.2), characterized in that the press has an automatic feed (4) for feeding a solid part (1) into the tool (5) of the press (20), wherein the joining punch (8.2) and a transfer punch (8.1) hold the solid part (1) under pressure and transfer it into the working space (6), and a joining space (9) is provided in the working space (6) by means of the transfer punch (8.1) for transferring the solid part (1) by means of the joining punch (8. 2) and the transfer punch (8. 1) into the joining space (9), the press (20) having a control device, the control device controlling at least a transfer of the solid part (1) into the working space (6), a computer program product being implemented on the control device, which computer program product is configured to carry out a method according to one of the preceding claims, in which the transfer punch is controlled in such a way that it preserves the joining space (9) in the working space (6), wherein a circumference of the joining space (9) is at least partially filled with the powdery material, and the joining punch (8.2) and the transfer punch (8.1) jointly transfer the solid part (1) into the joining space (9), the solid part (1) projecting out of a surface (16) of the powder-metallurgical part (2) after the working cycle.
5. Composite part (3) for material bonding by means of a sintering process comprising at least one powder-metallurgical part (2) compacted from a powdery material (7) and at least one solid part (1), characterized in that the composite part is produced by the method according to one of the preceding claims 1 to 3, wherein

   - the powder-metallurgical part (2) has a shrinkage on sintering which is greater than or equal to a shrinkage of the solid part (1), and

   - the solid part projects from a surface (16) of the powder-metallurgical part (2), the solid part (1) having a thread via which the solid part (1) and the powder-metallurgical part (2) form a positive connection.
6. Composite part (3) according to claim 5, wherein the powdery material (7) and the solid part (1) are comprised of the same alloy.
7. Composite part (3) according to claim 5, wherein the solid part (1) and the powdery material (7) are comprised of different alloys.
8. Composite part (3) according to one of claims 5 to 7, wherein it is sintered.
9. Composite part (3) according to one of claims 5 to 8, wherein several solid parts (1) are arranged in the composite part (3).
10. Composite part (3) according to one of claims 5 to 9, wherein at least one solid part (1) is arranged in more than one powder-metallurgical part (3) and connects these.

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