WO2011045303A2

WO2011045303A2 - Powder press

Info

Publication number: WO2011045303A2
Application number: PCT/EP2010/065254
Authority: WO
Inventors: Alex Wehrli; Daniel Meier; Beat Straub
Original assignee: Osterwalder Ag
Priority date: 2009-10-13
Filing date: 2010-10-12
Publication date: 2011-04-21
Also published as: WO2011045303A3; EP2311587A1

Abstract

The invention relates to a powder press (1) for producing a pellet from a powder material, comprising a frame (2), an upper die arrangement (3), a lower die arrangement (5), and a die plate arrangement (4) disposed between the two die arrangements. The die plate arrangement defines a mold cavity, into which the powder material can be filled and the upper die arrangement (3) and the lower die arrangement (5) can then be pressed against each other to form the pellet. The upper die arrangement (3) has an upper spindle drive (6). The die plate arrangement (4) and/or the lower die arrangement (5) comprise at least one lower spindle drive (7, 8).

Description

powder Press

The invention relates to a powder press for producing a compact of a powdery material, in particular from

Metal powder or ceramic powder.

Such a powder press includes a frame, an upper punch assembly, a lower punch assembly, and a die assembly disposed between the two punch assemblies. The

Die assembly defines a mold cavity into which the powdered material can be filled. Thereafter, the upper punch assembly and the lower punch assembly can be pressed against each other to form the compact.

Known powder presses of this type use controlled hydraulic drives for the movement of the punch assemblies (so-called.

"Hydraulic presses") or electric motors that are passive

Driving elements such as belts, gears, eccentrics, toggle and the like. Driving the punch assemblies (so-called "mechanical presses")

Hydraulic variant gives a high precision and dynamics even with large moving masses, but this is bought with relatively high energy consumption. In the motor variant, the energy consumption is lower. Due to the passive elements in the drive train, however, only lower rigidity and less dynamics are achieved. Moreover, the said passive drive elements of the engine variant are not only because of their

Susceptibility, but also due to their wear a significant cost factor.

The invention has for its object to provide a powder press, in which the said disadvantages of known powder presses are largely avoided.

This object is achieved by a powder press for producing a compact of a powdery material, with a frame, an upper punch assembly, a lower punch assembly and a between the two punch assemblies arranged die assembly which defines a mold cavity into which the powdered material is fillable and then to form the compact the upper

Stamp assembly and the lower punch assembly are pressed against each other, according to the invention on the one hand, the upper punch assembly has an upper spindle drive and on the other hand, the die assembly and / or the lower punch assembly at least one lower

Spindle drive has. The inventive use of one or more spindle drives results in a short drive train ("direct drive"), whereby a high rigidity and thus high dynamics of

Press drive is achieved even with large moving masses and / or large pressing forces. The invention thus has on the one hand for the upper punch assembly an upper direct drive and on the other hand for the

Matrizenanordnung and / or the lower punch assembly at least one lower direct drive. Such a direct drive on the powder press according to the invention is preferably characterized in that the drive motor acts directly on the spindle and this in turn acts directly or via a plunger on the punch arrangement or on the die arrangement, i. that no belt, gear, eccentric, toggle lever or the like is provided between the drive motor and the spindle and between the spindle and the punch arrangement or between the spindle and the die arrangement.

Preferably, the spindle drives are controlled spindle drives. As a result, by controlling the spindle drives in the pressing process, e.g. the properties of a particular

Powder material and the desired properties of one of

Consider the powder material produced compact. But also damage to the press can be avoided, which could be caused by incorrect operation or malfunction of the press.

It is particularly advantageous if the upper punch arrangement, the die arrangement and the lower punch arrangement have only spindle drives for their drive. This gives all the movable arrangements of the press a short drive train and thus a high rigidity, thereby a significant contribution is made to the accuracy of the inventive press.

Conveniently, the die assembly is movable and has a die drive. This allows operation of the

press according to the invention, optionally in a take-off process in which the die is withdrawn vertically from the compact after the pressing process, or in the ejection process in which the compact is ejected against the die friction by means of the lower punch. The die arrangement can also have a die spindle drive for this purpose.

Preferably, the controlled punch or die spindle drive is a servomotor assembly in particular with

Angle of rotation sensor for angle control, speed sensor for

Speed control or torque sensor for torque control and with a position sensor for detecting a linear position of the respective punch or the die. It is particularly advantageous if all drives are equipped by servo motors and their sensor or sensors for detecting one or more operating parameters, wherein preferably also the sensor or sensors associated memory means are provided for storing the operating data thus detected.

Conveniently, a spindle drive and preferably each of the spindle drives of the press comprises a servomotor arrangement with a sensor for detecting a spindle position and with a sensor for

Detecting a change in the spindle position. The sensor for detecting the spindle position is preferably a linear position sensor, e.g. an optical, an inductive or a resistive sensor. The sensor for detecting a change in the spindle position is preferably an angular position sensor, such as e.g. an optical, an inductive or a resistive sensor.

In an advantageous embodiment, a spindle drive, preferably each of the spindle drives, comprises a servomotor arrangement with a rotational position sensor for detecting a rotational position of the spindle and with a displacement position sensor for detecting a displacement position of the spindle Spindle, wherein the rotational position sensor and the displacement position sensor along the spindle longitudinal direction are arranged spaced from each other. Preferably, the displacement position sensor or linear position sensor is arranged closer to the punch-side or die-side end of the spindle, while the rotational position sensor or angular position sensor is arranged closer to the motor end of the spindle. Thereby, deviations of the spindle linear position occurring during operation of the spindle under load can be detected between calculated linear position values resulting indirectly from the measured spindle angular position and measured linear position values passing directly through result in the measurement by means of the linear position sensor.

By evaluating these deviations, statements can be made about the state of the powder press according to the invention. In particular, necessary preventive maintenance can be better planned. The spindle press according to the invention preferably contains a comparison unit in which the deviations between the calculated linear position values and the measured linear position values are predetermined

Reference deviations (thresholds) are compared. The comparison unit is connected to a display unit such that when the detected deviations exceed the reference deviations, the display unit displays a message regarding the next recommended maintenance of the powder press.

It is also advantageous if a spindle drive and preferably each of the spindle drives includes a servomotor arrangement with a sensor for detecting a spindle torque. This allows a shutdown of the press, if at least one of the spindle drives a torque is transmitted, which exceeds a maximum allowable value. At the

Exceeding the maximum torque, an emergency stop can be initiated. To determine the instantaneous spindle torque, the instantaneous current flowing through the electric motor driving the spindle can also be used together with the instantaneous voltage applied to this electric motor whose product is identical to the product of momentary torque and instantaneous speed of the electric motor. As a result, it is not only possible to implement the initiation of an emergency stop, but it is also possible to carry out an idle stroke, ie, a rotation and axial movement of the spindle, with the spindle. Such idle strokes may be performed from time to time after predetermined service intervals to determine the condition of the spindle, nut and bearings. If the measured idle stroke exceeds a maximum allowable idle stroke, it may serve to provide early detection of mechanical damage, allowing for preventative maintenance. However, it is also possible for any deviations from a temporal desired-current pattern profile, for example of such an idle stroke, to be detected and used as a basis for decision-making for preventive and / or warning measures.

Preferably, the screw press according to the invention contains a further or the same as the comparison unit mentioned above, in which such

Deviations between the detected current values or current flow patterns and the predetermined reference values or reference patterns are compared. Also, this comparison unit is connected to a display unit such that when the detected deviations exceed the reference deviations, the display unit displays a message regarding the next recommended maintenance of the powder press.

In a particularly preferred embodiment of

The powder press according to the invention is a hollow shaft electric motor for generating a controlled rotary drive. Inside the hollow shaft is the rotating element of the spindle drive. This allows a compact design, in particular a low overall height, and a particularly short drive train in the inventive press.

Preferably, a spindle drive and preferably each of the spindle drives includes a threaded rod-nut block unit having a

Threaded rod external thread and a complementary

Nut block internal thread. About the mother block, with the

rotatably threaded rod is engaged and performs only a linear movement along the longitudinal axis of the threaded rod when turning the threaded rod about its longitudinal axis, a torque-free Linear drive can be generated. In a preferred embodiment, the

Threaded rod by means of the motor, in particular by means of a servomotor, rotationally driven, and the mother block is rigidly connected to the punch assembly or with a plunger or in one piece.

In a particularly preferred embodiment, the upper punch assembly, the die assembly or the lower punch assembly have two or more identical spindle drives arranged parallel to each other. By a plurality of parallel and parallel driving forces on a punch or die assembly performing spindle drives can be a given linear or axially acting driving force in such

Arrangement (punch or die) not only torque-free, but also be introduced practically without bending. This too is an important contribution to increasing the accuracy of the inventive press, in particular in the production of compacts having large dimensions transverse to the axial pressing direction. In addition to the mentioned even

Force introduction into the corresponding punch arrangement also offers the possibility of torque or angular momentum compensation during operation of the powder press, for which, in particular, the moving parts of two parallel identical spindle drives with mutually opposite

Rotary movements can be driven. A further advantage of the two or more identical spindle drives arranged parallel to one another is the lower overall height which can be achieved in the axial direction, i. in the direction of the press forces.

Preferably, the powder press includes a control unit or a control unit for controlling the movement of the

Spindle drives. The control unit or control unit is designed in particular for the synchronized movement of the spindle drives and in particular for the mutual compensation of the individual angular momenta of the spindle drives. In order to compensate the individual angular momenta of the

To achieve spindle drives, it is particularly advantageous if the moving parts of two parallel identical spindle drives can be driven with mutually opposite rotational movements. For angular momentum compensation then only have the same opposite Rotation speeds of the spindle drives are maintained. This then also results in the same axial velocities of the parallel identical

Spindle drives. As a controlled variable, the linear force and / or the torque of the spindle can be used as an alternative to the linear position or the angular position of the spindle or alternatively to the linear velocity or the angular velocity of the spindle. Particularly advantageous is the use of a combination of these variables as a controlled variable.

In a particularly advantageous embodiment of the

According to the invention powder press, the upper punch assembly has a single upper spindle drive, the die assembly or the lower punch assembly has two lower spindle drives. The design with two lower spindle drives on the die assembly allows the

Provision of a trigger-operated powder press. The design with two lower spindle drives on the lower punch assembly makes it possible to provide a powder press operating according to the ejection method.

Conveniently, the spindle drives included

Ball screws or satellite roller spindles (i.e., roller screws) to minimize the friction between the rotating threaded rod and the nut block, and thus a virtually torque-free

Axialantrieb over the mother block to achieve.

Preferably, the hollow shaft motor contains braced bearings. In addition, cooling fins may be provided on the housing of the hollow shaft motor, wherein the hollow shaft motor is expediently assigned a fan. These measures enable a play-free drive or minimize thermal dimensional changes on the engine and on the spindle, which also increases the precision of the inventive powder press.

The described powder press according to the invention not only enables the high precision and high quality achieved due to its high rigidity

Dynamic, but also characterized by low maintenance and a small number of power transmission lines (no Hydraulic hoses) and a small number of passive drive elements (no belt, gear, eccentric, toggle and the like.).

The embodiment with a hollow shaft motor, in which preferably each spindle drive comprises a hollow shaft electric motor as the drive unit and each fan motor is associated with a fan, is characterized by the fact that it does not have any mechanical (passive) power transmission means, e.g. Belt drives, etc., nor any liquids, such as Hydraulic fluid or coolant needed.

Further advantages, features and applications will become apparent from the following description of preferred embodiments of the inventive powder press with reference to the drawing, wherein:

Fig. 1 is a perspective view of a schematically illustrated inventive powder press with three vertical spindle drives;

Fig. 2 is a sectional view of the powder press of Fig. 1 taken along a vertical plane in which the vertical spindle axes of the three

Spindle drives run;

Fig. 3A is a perspective view of a schematically illustrated spindle drive according to a first variant;

Fig. 3B is a sectional view of the spindle drive of Fig. 3A taken along a plane containing the spindle axis;

Fig. 4A is a perspective view of a schematically illustrated spindle drive according to a second variant;

Fig. 4B is a sectional view of the spindle drive of Fig. 4A taken along a plane containing the spindle axis; Fig. 5 is a perspective view of the spindle drive according to the first variant of Figs. 3A and 3B, which is attached to the frame of the powder press according to the invention; and

Fig. 6 is a perspective view of the spindle drive according to the second variant of Fig. 4A and 4B, which on the frame of

attached powder press according to the invention.

In Fig. 1 is a perspective view of a schematically illustrated inventive powder press 1 with three vertical spindle drives 6, 7, 8 is shown. The powder press 1 contains a frame 2 with an upper

Frame plate or upper cross-brace 2a and a lower

Frame plate or lower cross brace 2f. Between the top

Frame plate 2a and the lower frame plate 2f extend four vertically extending prismatic, in particular cylindrical frame columns 2b, 2c, 2d, 2e, viewed from above in the vertices of a rectangle

(Frame column rectangle) are arranged. These four frame columns 2b, 2c, 2d, 2e together with the two frame plates 2a and 2f form a stable base frame on which movable components of the powder press 1 are mounted.

The two main movably mounted components of the powder press 1 are an upper punch assembly 3 and a

Die assembly 4. A lower punch assembly 5 is fixedly attached to the lower frame plate 2f of the frame 2. It forms another essential component of the powder press. 1

Viewed from above, the upper punch arrangement 3 essentially appears as a rectangle, in the corners of which guide sleeves 3a, 3b, 3c, 3d are formed. Also, the die assembly 4 appears viewed from above substantially as a rectangle, in its vertices

Guide sleeves 4a, 4b, 4c, 4d are formed.

Similar to the four frame columns 2b, 2c, 2d, 2e, four vertically extending prism-shaped, in particular cylindrical, extend between the upper frame plate 2a and the lower frame plate 2f Guide rods 2k, 21, 2m, 2n, which, viewed from above, are likewise arranged in the corner points of a rectangle (guide pillar rectangle), which is smaller than and disposed within the frame pillar rectangle.

The upper punch assembly 3 is vertically slidably supported by its guide sleeves 3a, 3b, 3c, 3d on the four guide rods 2k, 21, 2m, 2n of the frame 2. The die assembly 4 is by means of her

Guide sleeves 4a, 4b, 4c, 4d to the four guide rods 2k, 21, 2m, 2n of the frame 2 mounted vertically sliding.

The lower portion of the frame 2 includes four frame posts 2g, 2h, 2i, 2j which extend downward from the lower frame plate 2f and support the entire weight of the powder press 1.

An upper spindle drive 6 fixed to the upper frame plate 2a serves to drive the upper punch assembly 3. Two identical lower spindle drives 7, 8 fixed to the lower frame plate 2f cooperate to drive the die assembly 4.

The upper punch assembly 3, the lower punch assembly 5 and between the two punch assemblies 3, 5 arranged

Die assemblies 4 define a mold cavity into which the powdered material may be filled, after which the upper die assembly 3 is pressed against the lower die assembly 5 to form the compact. Here are the bottom surface of the upper and movable

Stamping arrangement 3 and the uppermost surface of the lower and stationary die assembly 5 inside the mold cavity of the likewise movable die assembly 4th

A Dosierschuh drive linkage 19 (see also Fig. 2) is also attached to the frame 2. It serves to drive a metering shoe 20, with which the powdery material in the mold cavity of

Matrizenanordnung 4 is pushed. The powdery material is in this case via a powder line, not shown, from a powder container to the Dosing shoe 20 transported. A servomotor 21 serves to drive the

Dosierschuh drive linkage 19, at the end of the dosing shoe 20 is attached.

FIG. 2 shows a sectional view of the powder press of FIG. 1 along a vertical plane, in which the vertical spindle axes of the three spindle drives 6, 7, 8 run. Some components of the powder press 1

therefore appear in Fig. 2 as a sectional view, while arranged in the rear half of Fig. 1 components of the powder press in Fig. 2 as

Front view appear.

In particular, one recognizes the upper punch assembly 3, the die assembly 4 and the lower punch assembly 5 and the upper spindle drive 6 and the two lower spindle drives 7, 8. These components 3, 4, 5, 6, 7, 8 all appear in a vertical section.

The powder press 1 shown in Fig. 1 and in Fig. 2 allows the powder pressing by the so-called. Deduction process. Here is the

Mold cavity filled with powder. Subsequently, the upper

Stamp assembly 3 from above down against the lower, fixed

Stamping assembly 5 and moved into the mold cavity of the die assembly 4, wherein the powder is compacted in the mold cavity into a compact. After pressing, the die assembly 4 is moved down ("pulled off") and the upper punch assembly is moved back up again exposing the compact lying on the lower punch assembly 5. The pressing operation is complete.

In Fig. 3A is a perspective view of a schematically illustrated spindle drive 6 is shown according to a first variant, while in Fig. 3B is a sectional view of the spindle drive of Fig. 3A along a the

Spindle axis containing plane is shown. A hollow shaft motor 10 surrounds a spindle or threaded rod 1 1. The projecting into the interior of the hollow shaft motor spindle 1 1 1 rotatably connected to the rotor of the hollow shaft motor 10 and axially fixed and can therefore be rotated by this about the spindle longitudinal axis. A fastening means 12, for example in the form of a Double flange, used to attach the stator or the housing of the hollow shaft motor 10 to the frame 2 of the powder press 1 (see also FIG.

5). A thread-free portion of the spindle 1 1 is inside the

Fastener 12 by means of a bearing 13, e.g. a rolling bearing, rotatably mounted about the spindle longitudinal axis.

A nut block 15 is via its internal thread (not shown) and via the (not shown) external thread of the spindle 1 1 with this in engagement. The nut block 15 is rigid with a plunger 16, i. rotatably connected. The nut block / plunger unit 15/16 is axially displaceable on a guide block 18 and rotatably mounted with respect to its longitudinal axis or with respect to the spindle longitudinal axis. The plunger 16 is with the

Stamp assembly 3 is connected and makes it possible to drive these torque-free in the vertical direction downwards or upwards.

In Fig. 4A is a perspective view of a schematically illustrated spindle drive 6 is shown according to a second variant, while in Fig. 4B is a sectional view of the spindle drive of Fig. 4A along a the

Spindle axis containing plane is shown. A hollow shaft motor 10 'surrounds a spindle or threaded rod 1 1'. The inside of the hollow shaft motor 10 'projecting spindle 1 1' is rotatably connected to the rotor of the hollow shaft motor 10 ', but axially movable with respect to the rotor. The spindle 1 1 'can therefore be rotated by the hollow shaft motor 10' about the spindle longitudinal axis and with respect to the hollow shaft motor 10 'along the spindle longitudinal axis

be moved. A fastener 12 ', e.g. in form of

Double flange, used to attach the stator or the housing of the hollow shaft motor 10 'to the frame 2 of the powder press 1 (see also Fig.

6).

A nut block 15 'is via its internal thread (not shown) and via the (not shown) external thread of the spindle 1 1' with this in engagement. The nut block 15 'is fixedly secured in the double flange 12' fixed to the frame 2. A rotational movement of the spindle 1 1 'in one or the other direction of rotation leads to a movement of the spindle 1 1' up or down. A lower thread-free region of the spindle 1 1 'is by means of a bearing 13 ', such as a rolling bearing, in a bearing housing 17 around the

Spindle longitudinal axis rotatably mounted and fixed in the axial direction. The

Bearing housing 17 serves to be rigid on the upper punch assembly 3, i. rotatably secured. The spindle 1 1 ', which moves vertically upwards or downwards, moves the bearing housing 17, which is rigidly or non-rotatably attachable to the stamp arrangement 3, upwards or downwards. This makes it possible to drive the punch assembly 3 torque-free in the vertical direction downwards or upwards.

FIG. 5 shows a perspective view of the spindle drive according to the first variant of FIGS. 3A and 3B. This spindle drive is on

Frame 2 of a powder press 1 according to the invention attached.

FIG. 6 shows a perspective view of the spindle drive according to the second variant of FIGS. 4A and 4B. This spindle drive is attached to the frame 2 of a powder press 1 according to the invention.

Claims

claims

1 . Powder press (1) for producing a compact of a powdery material, with a frame (2), an upper one

Plunger assembly (3), a lower punch assembly (5) and one between the two punch assemblies (3, 5) arranged

A die assembly (4) defining a mold cavity into which the powdered material is fillable and thereafter the upper punch assembly and the lower punch assembly are pressable to form the compact, characterized in that the upper punch assembly (3) comprises an upper spindle drive (6). and that the die assembly (4) and / or the lower punch assembly (5) at least one lower

Spindle drive (7, 8).

2. Powder press according to claim 1, characterized in that the spindle drives (6, 7, 8) are controlled spindle drives.

3. Powder press according to claim 1 or 2, characterized in that the upper punch assembly (3), the die assembly (4) and the lower punch assembly (5) only spindle drives (6, 7, 8) for their drive.

4. Powder press according to one of claims 1 to 3, characterized in that a spindle drive (6, 7, 8), preferably each of the spindle drives (6, 7, 8), a servo motor arrangement with a sensor for detecting a spindle position and with a sensor for detecting a change in the spindle position.

5. Powder press according to claim 4, characterized in that a spindle drive (6, 7, 8), preferably each of the spindle drives (6, 7, 8), a servo motor arrangement with a rotational position sensor for detecting a rotational position of the spindle and with a shift position sensor for

Detecting a displacement position of the spindle, wherein the

Rotary position sensor and the displacement position sensor along the spindle longitudinal direction are arranged spaced from each other.

6. Powder press according to one of claims 1 to 5, characterized in that a spindle drive (6, 7, 8), preferably each of the spindle drives (6, 7, 8), a servomotor assembly having a sensor for detecting a spindle torque.

7. Powder press according to one of claims 4 to 6, characterized in that the motor of the servomotor assembly for generating a controlled rotary drive is a hollow shaft electric motor (10; 10 ').

8. Powder press according to one of claims 1 to 7, characterized in that a spindle drive (6, 7, 8), preferably each of the spindle drives (6, 7, 8), a threaded rod-nut block unit (1 1, 15, 1 1 ', 15') with a threaded rod external thread and a thereto

Complementary female block internal thread has.

9. Powder press according to claim 8, characterized in that the threaded rod (1 1, 1 1 ') is rotationally driven by means of the motor and the mother block is rigidly connected to the stamp assembly or integral with this.

10. Powder press according to one of claims 1 to 9, characterized in that the upper punch assembly (3), the die assembly (4) or the lower punch assembly (5) has two or more mutually parallel identical spindle drives (7, 8) or

exhibit.

1 1. Powder press according to claim 10, characterized in that the movable parts of two parallel identical spindle drives (7, 8) can be driven with mutually opposite rotational movements.

12. Powder press according to one of claims 1 to 1 1, characterized in that it comprises a control unit or a control unit for controlling or controlling the movement, in particular for synchronized movement, the spindle drives (6, 7, 8), in particular with compensation of the individual Angular momentum.

13. Powder press according to one of claims 10 to 12, characterized in that the upper punch assembly (3) has a single upper spindle drive (6), and that the die assembly (4) or the lower punch assembly (5) has two lower spindle drives (7, 8).

14. Powder press according to one of claims 1 to 13, characterized in that the spindle drives recirculating ball spindles (13, 13 ') or satellite roller spindles.

15. Powder press according to one of claims 7 to 14, dadaurch characterized in that the hollow shaft motor has tensioned bearings.

16. Powder press according to one of claims 7 to 14, characterized in that the hollow shaft motor has on its housing cooling fins, and that the hollow shaft motor is associated with a fan.