This application represents the U.S. national stage entry of International Application No. PCT/EP2018/067688 filed Jun. 29, 2018, which claims priority to German Patent Application No. 10 2017 114 457.9 filed Jun. 29, 2017, the disclosure of which is incorporated herein by reference in its entirety and for all purposes.

The invention relates to a plane plate for a pressing tool of a press, in particular a powder press for producing green compacts. The invention furthermore relates to the use of a plane plate in a pressing tool of a press for producing a green compact. Green compacts which are capable of sintering are in particular produced by the press, thus green compacts which can be sintered after the pressing procedure. In particular, metallic and/or ceramic powders can be compressed so as to form green compacts in the press.

Known presses of this type comprise at least a die, an upper pressing tool comprising one or a plurality of upper punches, and a lower pressing tool comprising one or a plurality of lower punches. An internal circumferential face of the die forms the receptacle for the powder, or the green compact to be produced, respectively. At least one upper punch of the upper pressing tool can in particular move into the die along an axial direction by way of a first end side of the die that is open toward the top. The at least one upper punch herein slides along the internal circumferential face of the die and increasingly compresses the powder. At least one lower punch which moves into the die along the axial direction by way of a second end side of the die that is open toward the bottom, or moves between an upper position and a lower position in the die, respectively, can in particular be additionally provided. The powder is thus compressed between the at least one upper punch and the at least one lower punch so as to form a green compact, wherein the internal circumferential face of the die defines in particular a lateral contour of the green compact.

One or each pressing tool comprises in particular a plurality of punches, wherein at least one punch for compressing the powder is displaceable along the axial direction in relation to the at least one further punch. Each punch (and each component of the pressing tool that for transmitting the compression force is connected to said punch) herein can be assigned to a tool plane. A plane plate (also referred to as a tool plane plate) which is activated by at least one lifting cylinder and/or is displaced along the axial direction by the lifting cylinder is typically provided for displacing each (displaceable) punch. The plane plate can be guided by at least one guide column which extends along the axial direction. Twisting of the plane plate in a circumferential direction and/or tilting of the plane plate about an axis running along the radial direction is minimized or prevented, respectively, by way of the at least one guide column. The various plane plates at least of an upper or a lower pressing tool can be collectively guided by guide columns.

A punch holder which transmits a compression force transmitted from the plane plates to the at least one punch can additionally be disposed between the plane plate and the at least one punch which contacts the powder in the die. Furthermore, compression plates which transmit a compression force of the plane plate in the axial direction and in the radial direction toward the punches can be provided between the punch, or the punch holder, respectively, and the plane plate. The punch and punch holder, respectively, can be fastened to the compression plate or to the plane plate by way of clamping plates, or alternatively bayonet closures or bowl-shaped receptacles.

In the case of known pressing tools, or presses, respectively, the individual plane plates which are characterized by being guided by way of at least one guide column and one link to the at least one lifting cylinder, are mutually spaced apart in the axial direction and disposed on top of one another, that is to say that said plane plates are permanently disposed at different heights (levels) along the axial direction. A plane plate herein can be embodied so as to be cubic, cuboid, or disk-shaped. The plane plate extends between a centrally disposed receptacle for the compression plate, the punch holder, or the punch, along the radial direction at least up to a cylindrical guiding face which is provided for contacting one of the guide columns.

A press is known, for example, from U.S. Pat. No. 5,498,147. The plane plates illustrated therein are shaped so as to be rectangular in the cross section and have a consistent wall thickness. The plane plate is perforated in sub-regions such that a ram of the lifting cylinder, or a compression plate for connecting to the punch, respectively, can be received on the plane plate. The cross-sectional variations herein are however not present in the region between the guiding faces on the guide columns and the central receptacle for the compression plate, and are also not present continuously along an extent, but are in each case provided only at one position, specifically at the receptacle for the compression plate, wherein the cross-sectional variations are typically formed by lateral walls that run parallel with the axial direction.

The construction of a known press, or of a pressing tool, respectively, has a large height in the axial direction. The individual components of the respective tool plane (thus the punch, optionally the associated punch holder, optionally the associated compression plate) herein, proceeding from the die for each tool plane, extend dissimilarly far along the axial direction such that dissimilar elasticities are present for each tool plane. The elasticity of the tool plane describes in particular the deformation of the components of the tool plane in the axial direction as a result of a compression force acting by way of the lifting cylinders on the link, or by way of the punch or the punch holder on the receptacle, respectively. The unit of elasticity is: m/N [meter/Newton].

As a result of the dissimilar elasticities, demolding of the green compact to be produced can be specifically problematic on account of the dissimilar expansion of the components between different tool planes in the relaxation of the tool planes (compression force is reduced), wherein formations of cracks can arise in the green compact.

Proceeding therefrom, it is an object of the present invention to at least partially remedy or even solve the problems described with reference to the prior art. In particular, the dissimilarities in the elasticities are to be at least minimized, wherein the pressing tools are moreover capable of being produced, or provided, respectively, with a smaller installation height. The weight of at least the plane plates is furthermore to be ideally reduced. The assembly of the press, or of the plane plates, respectively, can thus be simplified and optionally also be carried out more rapidly. In particular, comparatively compact presses having a smaller installation height can thus also be used, such that material and costs can also be saved here.

In order for said object to be achieved, a plane plate according to the features of claim1and the use of a plane plate according to claim9are proposed. Advantageous embodiments are the subject matter of the dependent claims. The features listed individually in the claims can be combined with one another in a technologically expedient manner and can be supplemented by explanatory facts from the description and details from the figures, wherein further embodiment variants of the invention are indicated.

A plane plate for a pressing tool of a press, in particular of a powder press for producing green compacts, contributes to this end. Green compacts which are capable of sintering can in particular be produced by the press, thus green compacts which can be sintered after the pressing procedure. In particular, metallic and/or ceramic powders can be compressed so as to form green compacts in the press.

The plane plate can in particular be embodied so as to be integral.

The plane plate for activating a punch of the press by way of at least one lifting cylinder can be displaced along an axial direction. The plane plate has a link to the at least one lifting cylinder, at least one at least partially cylindrical guiding face which for contacting a guide column is parallel with the axial direction, and a centrally disposed receptacle for contacting the punch or the punch holder of the press. The plane plate has at least a first cross section which between the receptacle and the guiding face (or between the receptacle and a position along the radial direction on which the at least one guiding face is disposed in another cross section which runs offset in the circumferential direction, respectively) runs parallel with the axial direction and along a radial direction that runs so as to be perpendicular to the axial direction. At least a first region with a wall thickness and a first centerline is provided in said first cross section, wherein the first centerline runs at least partially at a first angle of at least 10 angular degrees and of at most 85 angular degrees in relation to the radial direction.

A plurality of lifting cylinders can be used for displacing the plane plates, wherein the plane plate in this instance has in each case one link to each lifting cylinder. The at least one lifting cylinder in relation to the plane plate can be disposed such that the plane plate about an axis which is parallel to the radial direction is impinged by as low a torque as possible which could cause tilting of the plane plate about said axis. For example, two lifting cylinders which along the circumferential direction are disposed so as to be mutually offset by 180 angular degrees are thus in particular provided.

The plane plate can have a plurality of (preferably four) at least partially cylindrical guiding faces which are disposed so as to be mutually spaced apart in a direction perpendicular to the axial direction. The plane plate can be guided by the at least one guide column along the axial direction across the at least one guiding face, said guide column extending along the axial direction. Twisting of the plane plate in a circumferential direction and/or tilting of the plane plate about an axis running along the radial direction is minimized, or prevented, respectively, by way of the at least one guide column. The plane plates at least of an upper or lower pressing tool can be guided by common guide columns.

The receptacle for contacting the punch or a punch holder of the press is in particular centrally disposed, that is to say (approximately) in a center of the plane plate when the latter is viewed along the axial direction. A central disposal of the receptacle is in particular present when said receptacle is positioned so as to be central between a plurality of links, or at an equal spacing from a plurality of links, respectively, thus in particular so as to be centric in relation to the force introduction points of the lifting cylinder. The receptacle can be disposed so as to be (centric) between a plurality of lifting cylinders and a plurality of guide columns such that the plane plate upon an impingement of the plane plate with a compression force about an axis parallel with the radial direction is impinged by as low a torque as possible which could cause tilting of the plane plate about said axis.

The receptacle can be embodied so as to be round, preferably circular. The receptacle can have a longitudinal axis which runs parallel with the axial direction and/or is disposed so as to be concentric with the receptacle. The radial direction extends perpendicular to the axial direction and in particular proceeding in each case from the longitudinal axis.

The receptacle can have a receptacle face for contacting and/or supporting the punch, or the punch holder, respectively. The punch, or the punch holder, respectively, can be fastened to the receptacle by way of a clamping plate, screw fitting, a bayonet closure, or similar.

The plane plate can have an upper side that points in a first axial direction, and a lower side that points in a second axial direction that is opposite to the first axial direction, a link to the at least one lifting cylinder, a centrally disposed receptacle for contacting the punch or a punch holder of the press, at least a first at least partially cylindrical guiding face which for contacting a first guide column in parallel with the axial direction, and a second at least partially cylindrical guiding face which for contacting a second guide column is parallel with the axial direction. On the lower side of the plane plate, the first guiding face can have a first lower end and the second guiding face can have a second lower end. The first lower end and the second lower end can be disposed at mutually dissimilar heights in relation to the axial direction, and thus can be disposed so as to be mutually spaced apart in the axial direction.

The plane plate can have four (or more) at least partially cylindrical guiding faces for contacting four guide columns (thus in each case one guide column), wherein each guiding face has a lower end. The lower ends of two guiding faces (or at least two guiding faces) can in each case be disposed at a common height.

In particular, two guiding faces are in each case provided, the lower ends of said guiding faces being disposed at a common height. Each of the two at least partially cylindrical first guiding faces thus configures in particular a first lower end, and each of the two at least partially cylindrical second guiding faces thus configures in particular a second lower end. The first lower end and the second lower end can be disposed at mutually dissimilar heights in relation to the axial direction.

The first lower end and the second lower end can be disposed on the lower side of the plane plate.

The guiding faces can be disposed at dissimilar heights. Tilting of the plane plate about an axis that runs perpendicular to the axial direction can thus be reduced, or completely prevented, respectively, in comparison to a plane plate having guiding faces that are disposed exclusively at a common height.

The two guiding faces having the lower ends disposed at the common height can be disposed so as to be mutually offset by 90 or 180 angular degrees in a circumferential direction.

All lower ends of the guiding faces of the one plane plate can preferably be disposed at mutually dissimilar heights in relation to the axial direction.

The lower ends of the guiding faces of a plane plate which are disposed at dissimilar heights in relation to the axial direction are in each case in particular mutually spaced apart by at least 5 millimeters, in particular at least 20 millimeters, preferably at least 100 millimeters, particularly preferably at least 200 mm, along the axial direction.

The first guiding plane on the upper side of the plane plate has in particular a first upper end, wherein the lower end and the first upper end are disposed at mutually dissimilar heights in relation to the axial direction, and thus so as to be mutually spaced apart at a distance in the axial direction. The first lower end and the second lower end are disposed so as to be mutually spaced apart by at least 50% of the distance, preferably by at least 100% of the distance, particularly preferably by at least 150% of the distance, in the axial direction.

The plane at least in a first cross section which between the receptacle and the guiding face (or between the receptacle and plate, a position along the radial direction where the at least one guiding face is disposed, respectively) runs parallel with the axial direction and along the radial direction has at least a first region with a wall thickness and a first centerline (of the wall thickness). The first region in the radial direction extends across a first extent in which the first centerline runs at a first angle of at least 10 angular degrees, in particular at least 20, preferably at least 45, in relation to the radial direction. The first centerline runs in particular at a first angle of at most 85 angular degrees, preferably at most 80 angular degrees.

The wall thickness describes the material thickness of the plane plate in a manner parallel to the axial direction. The centerline runs through the geometric centers of area of the section faces of the plane plate that lie in the first cross section. The first centerline can be defined by the centers of the wall thickness present at the respective radial position.

Known plane plates have a substantially consistent wall thickness in the axial direction. In a cross section which between the receptacle and the guiding face runs parallel with the axial direction and along a radial direction that runs so as to be perpendicular to the axial direction, the plane plates are embodied so as to be in particular rectangular having a substantially consistent wall thickness, wherein an upper side of the plane plate and a lower side of the plane plate and thus also a centerline of the wall thickness extend so as to be parallel with the radial direction. The plane plates illustrated in U.S. Pat. No. 5,498,147 are shaped so as to be rectangular in the cross section and have a consistent wall thickness. The plane plate is perforated in sub-regions such that a ram of the lifting cylinder, or a compression plate for connecting to the punch, respectively, can be received on the plane plate. The cross-sectional variations, or changes to the wall thickness, respectively, herein are however not present in the region between the guiding faces on the guide columns and the central receptacle for the compression plate, but are in each case provided only at one position, specifically at the receptacle for the compression plate, wherein the cross-sectional variations are typically formed by lateral walls that run so as to be parallel with the axial direction. This known teaching is presently deviated from.

The first region in the radial direction can extend across a first extent which is at least 10%, in particular at least 20%, preferably 30%, of a smaller spacing between the central receptacle and the guiding face (for example, between the receptacle and a position along the radial direction on which the at least one guiding face is disposed) in the first cross section along the radial direction. The first extent can be at least 5 millimeters, at least 10 millimeters, or at least 20 millimeters.

The receptacle on the plane plate can comprise a receptacle face or a functional region (hereafter also referred to as parts of the receptacle) on which the punch or a punch holder can be disposed. The smallest spacing can be determined between the guiding face and a part of the receptacle which along the radial direction is disposed so as to be closest to the guiding face.

The plane plate in at least a second cross section which runs along the radial direction between the receptacle and the guiding face (or between the receptacle and a position along the radial direction on which the at least one guiding face is disposed, respectively), and in relation to the first cross section in the circumferential direction is disposed so as to be rotated by an angular range (for example by at least one angular degree or at least 5 angular degrees), can have at least a second region have with a wall thickness and a second centerline. The second region in the radial direction herein extends across a second extent which differs from the first extent (is larger or smaller than the latter). In the second cross section, the second centerline runs at a second angle of at least 10 angular degrees, in particular at least 20, preferably at least 45, in relation to the radial direction. The second centerline runs in particular at a second angle of at most 85 angular degrees, preferably at most 80 angular degrees.

Optionally, a cross section that in the circumferential direction is disposed so as to be rotated by an angular range of 90 or of 180 angular degrees in relation to the first cross section can exclusively be embodied so as to be identical to the first cross section.

The second cross section can run so as to be parallel with the axial direction and along the radial direction, thus so as to be rotated only in one circumferential direction in relation to the first cross section.

In particular, the first angle differs from the second angle by at least 10 angular degrees, in particular by at least 20 angular degrees.

The plane plate in the first cross section (or else in the second cross section) can have a third region that in the radial direction is contiguous to the first region, wherein the third region has a third centerline which at least partially runs at a third angle of at least 10 angular degrees, in particular at least 20 angular degrees, and at a third angle of at most 85 angular degrees, in relation to the radial direction. The first angle (or the second angle) and the third angle are oriented so as to be mutually opposite in relation to the radial direction. The explanations made in the context of the first centerline apply in analogous manner to the third centerline.

The plane plate can have an upper side pointing in a first axial direction, and a lower side pointing in a second axial direction that is opposite to the first axial direction. The upper side and/or the lower side of the plane plate in the first region of the first cross section can run so as to be parallel with the first centerline and/or at a first angle of at least 10 angular degrees, preferably at least 20 angular degrees, particularly preferably of at least 45 angular degrees, and at a first angle of at most 80 angular degrees, in particular of at most 85 angular degrees, in relation to the radial direction.

The upper side and/or the lower side of the plane plate in the third region of the first cross section can run so as to be parallel with the third centerline and/or at a third angle of at least 10 angular degrees, preferably at least 20 angular degrees, particularly preferably of at least 45 angular degrees, and at a third angle of at most 80 angular degrees, in particular of at most 85 angular degrees, in relation to the radial direction.

The first cross section can extend through the guiding face. The guiding face can have a lower end (on the lower side of the plane plate) which is disposed at a height (level) in relation to the axial direction. A turning region of the plane plate can be disposed in the first cross section between the first region and the third region. Said reversing region in relation to the axial direction can be disposed below the lower end.

Furthermore proposed is a pressing tool for a press, at least comprising a first plane plate and a second plane plate. At least the first plane plate for activating a punch of the press by way of at least one lifting cylinder is displaceable along an axial direction. At least the first plane plate has a link to the at least one lifting cylinder. Each plane plate for contacting a guide column that is common to the plane plates has in each case at least one at least partially cylindrical guiding face, and for contacting the punch or a punch holder of the press has in each case one centrally disposed receptacle. The plane plates along an axial direction are capable of being disposed on top of one another such that the respective at least one guiding face of each plane plate is disposed so as to be coaxial with the respective other at least one guiding face. At least the first plane plate can be embodied like a plane plate described above. The plane plates are capable of being disposed so as to be at least partially mutually overlapping along the axial direction and along the radial direction. Said plane plates are in particular capable of being mutually disposed such that at least parts of the two plane plates are disposed at an identical height in relation to the axial direction (and thus neighbor one another along the radial direction).

The plane plates can be disposed so as to be nested in one another (and thus not exclusively so as to be mutually spaced apart in the axial direction) such that an installation height of the pressing tool can be reduced. Nested herein means that the plane plates are capable of being disposed on top of one another along the axial direction, and in the radial direction are capable of being disposed so as to have at least parts of the plane plates beside one another.

The plane plates of the pressing tool for contacting two guide columns that are common to the plane plates can have in each case at least two at least partially cylindrical guiding faces. The first plane plate has a first at least partially cylindrical guiding face having a first lower end, and the second plane plate has a third at least partially cylindrical guiding face having a third lower end. The first plane plate in relation to the axial direction is disposed above the second plane plate. The plane plates are mutually disposed such that the first guiding face contacts a first guide column of the common guide columns, and the third guiding face contacts a second (thus another) guide column of the common guide columns. The first lower end in relation to the axial direction is disposed below the third lower end.

As has been explained above in the context of the plane plate, the guiding faces of a plane plate can be disposed at dissimilar heights such that the guiding faces of different plane plates in the axial direction are capable of being disposed on different guide columns in a sequence that is reversed in relation to the plane plates. Tilting of the plane plates about an axis that runs perpendicular in relation to the axial direction can thus be reduced, or completely prevented, respectively, in comparison to a plane plate having guiding faces that are disposed exclusively at a common height, and a nested arrangement of the plane plates can be implemented such that an overall lower installation height of the pressing tools is enabled.

The explanations pertaining to the plane plate apply likewise to the pressing tool and vice versa.

Furthermore proposed is the use of a plane plate, in particular a plane plate described above, in a pressing tool, in particular in a pressing tool described above, of a press for producing a green compact. Sintering-capable green compacts, thus green compacts which can be sintered after the pressing procedure can in particular be produced by the press. In particular, metallic and/or ceramic powders can be compressed so as to form green compacts in the press.

The plane plate for activating a punch of the press by way of at least one lifting cylinder is displaceable along an axial direction. The plane plate has a link to the at least one lifting cylinder, at least one at least partially cylindrical guiding face which for contacting a guide column is parallel with the axial direction, and a centrally disposed receptacle for contacting the punch or the punch holder of the press. The plane plate, at least in a first cross section which between the receptacle and the guiding face runs parallel with the axial direction and along a radial direction that runs so as to be perpendicular to the axial direction (or between the receptacle and a position along the radial direction on which the at least one guiding face is disposed, respectively), has at least a first region with a wall thickness and a first centerline, wherein the first centerline runs at least partially at a first angle of at least 10 angular degrees and of at most 85 angular degrees in relation to the radial direction.

The explanations pertaining to the plane plate and/or the pressing tool likewise apply to the proposed use and vice versa.

A method for activating a press is in particular implementable by way of the plane plate and/or the pressing tool, wherein the press comprises at least one guide column and at least one lifting cylinder as well as a pressing tool (described above). The method comprises at least the following steps:

providing the press and the pressing tool;

disposing the first plane plate and the second plane plate in the press; wherein the plane plates along an axial direction are disposed on top of one another such that the respective at least one at least partially cylindrical guiding face of each plane plate is disposed so as to be coaxial with the respective other at least one guiding face;

wherein the plane plates are disposed so as to be mutually overlapping along the axial direction such that at least parts of the two plane plates are disposed at an identical height in relation to the axial direction (and thus so as to neighbor one another along the radial direction).

The design of the plane plate can be generated using the known production methods such as turning, milling, sawing, boring, as well as grinding, wire cutting, vertical eroding and hard milling, etc. The plane plate can be produced by so-called additive methods, for example laser sintering (3D printing method for producing three-dimensional structures by sintering a pulverulent initial material; workpiece is generated layer-by-layer). On account thereof, a free design of the plane plate is possible, wherein the weight of the plane plate can be reduced and a stiffness, or a elasticity, respectively, of the plane plate can be set in a targeted manner.

The stiffness of the plane plate refers in particular to the resistance of the plane plate in relation to any deformation in the axial direction counter to a compression force that acts by way of the lifting cylinder on the link, or by way of the punch or the punch holder on the receptacle, respectively. The unit of stiffness is: N/m [Newton/meter].

The stiffness can be determined as follows, for example: by way of a FEM analysis in which the deformation, in particular the elastic deformation, of the plane plate at a specific compression force [N] which acts on the plane plate in particular in the axial direction is determined (thus the displacement of the material of the plane plate in the direction of the axial direction, said displacement being indicated in [m]). The ratio of said variables (compression force [N]/material displacement [m]) represents the stiffness of the plane plate.

The lower the stiffness of the plane plate, the higher the elastic deformation (elasticity) of the plane plate. Dissimilar stiffnesses of the different plane plates in the production of green compacts (specifically when demolding, or during the relaxation of the compression force, respectively) can lead to the formation of cracks and thus to a destruction of the green compact.

The elasticity, or the stiffness, respectively, of at least two plane plates, in particular of all plane plates (as described above), preferably varies by at most 20%, or at most 10%.

It is to be noted that the numerals (“first”, “second” . . . ) used herein primarily serve (only) for differentiating a plurality of items or variables of the same type, thus in particular do not indicate any interdependence and/or sequence of said items or variables. Should an interdependence and/or sequence be required, this is explicitly stated here, or this is derived in a manner obvious to the person skilled in the art when studying the specifically described design embodiment.

