EP0077897A2 - Press for making dimensionally stable pressed articles from powdery material - Google Patents

Abstract

In a press having an upper bear and a lower bear for the production of dimensionally stable compacts from powdery material with a base plate, a die plate and a lower punch which is hydraulically displaceable relative to the base plate and the die plate, the base plate and the die holding plate being parts of a die holder plate and a lower one Coupling plate are connected by means of tie rods framework, which is connected to the upper bear via a connecting piece which can be displaced in the pressing direction relative to the framework, while the lower bear of the press is connected to the lower coupling plate, the task is to further develop the press in such a way that the conditions for this are created that the most uniform and dense distribution possible in the press part during pressing and the press can be controlled with the aid of the most modern electronic control devices, solved by counterparts carrying machine parts he the base plate is mounted on hydraulic cylinder-piston systems, sit in the pressing position on fixed stops with respect to the press frame and for ejecting the compact after removing the die after the surfaces of the compact that are in contact with the die are released together until the die is released next contact surface can be raised gradually.

Description

The invention relates to a press having an upper bear and a lower bear for producing dimensionally stable compacts from powdery material. Such compacts are to be understood, for example, as gears, shock absorber pistons, synchronous parts for automatic transmissions or the like. They generally consist of iron powder, ferrite powder or ceramic or similar powders.

An obviously used press of this type originating from the house of the applicant has a base plate, a die plate and a lower stamp which can be moved hydraulically relative to the base plate and the die plate. The base plate and die plate are parts of a die plate and a lower coupling plate Drawbar connected framework, which is connected to the upper bear via a connecting piece which can be displaced in the pressing direction relative to the framework, while the lower bear of the press is connected to the lower coupling plate.

In the known press, the base plate receives the lower stamp in a correspondingly stepped form, possibly also composed of different stamp parts. When removing the lower punch, even if it is composed of several punch parts, different forces inevitably occur within the compact, which are due to the frictional forces between the corresponding die or stamp part and the compact to be removed and very often lead to the fact that the Compact is destroyed. In addition, it is difficult to achieve a uniform density distribution in the compact with the known press.

The task of such a press is to further develop it in such a way that the prerequisites are created for the density distribution in the pressed part to be as uniform as possible during pressing and for this purpose the press can be controlled using the latest electronic control devices. Furthermore, there should be the possibility during removal from the mold that the different compression of the same can be compensated by corresponding movement control by readjusting the press rams.

This object is achieved in that lower punch-bearing machine parts are mounted opposite the base plate via hydraulic cylinder-piston systems, in the pressing position on fixed stops with respect to the press frame and for ejecting the compact after removing the die after the die has been released Touching surfaces of the compact together until the release next contact surface can be raised gradually.

In such a press, the pressing position forms a lowermost fixed stop for all lower punches, which can be adjusted to a certain extent with respect to the individual lower punches, but also basically defines the pressing position even after such an adjustment.

The compact is ejected in the simplest manner by first pulling off the die, whereupon the compact, with the support of all the lower punches, is released from the die. Then, with the next lower punch in the end position at the level of the die, the rest of the lower punches are raised together until the next step of the compact has been released. This gradual start-up continues until finally the compact is only seated on a central lower punch from which it can be ejected.

The sequence of this work process depends exclusively on the shape of the compact. In any case, however, it is ensured that there are only frictional forces on the compact during ejection of the next stage within this stage, so that a gradual relief of the compact takes place in the circumferential direction and thus excessive pulling forces are avoided, which can lead to structural changes in the compact. The compact can be easily detached from an existing central mandrel because it progressively expands due to its progressive relaxation and can therefore be easily removed.

A particular advantage of the invention is that each machine part carrying a lower punch is one on the Base plate fixed measuring element can be assigned, which serves as a path scanner for the path of these machine parts in the filling or ejection position. In a very simplified case, there is only a central pin that takes part in the movement of the die holding plate and the speed of which can be freely controlled in relation to the die holding plate. The center pin is advantageously attached to the piston of a hydraulic cylinder which is coupled to the lower clutch plate.

In the press according to the invention it is possible to move the speed of the individual machine parts carrying the lower punches completely independently of one another from the start of the pressing process. In addition, they can be moved into their final pressing position depending on the pressure building up between the upper punch and the individual lower punches in the material to be pressed. The control can be carried out with the most modern aids, for example with the aid of control electronics.

With the press according to the invention, it is possible to move all lower punches and also the central pin at preselected speeds regardless of temperature, pressure and friction conditions. An exactly reproducible powder flow is thereby achieved during the compaction process.

The number of different machine parts, each with a lower punch, is arbitrary and only depends on the possibility of accommodating them in the press frame.

• Fig. 1 einen Vertikalschnitt durch die zwischen Ober- und Unterbären der Presse befindlichen Teile;
• Fig. 2 einen Schnitt im wesentlichen längs der Linie II-II der Fig. 3;
• Fig. 3 einen Schnitt längs der Linie III-III der Fig. 1;
• Fig. 4 einen Halbschnitt im wesentlichen entsprechend demjenigen nach Fig. 3 mit eingesetzten Preßwerkzeugen zur Herstellung eines mehrstufigen Werkstückes in der Füllstellung;
• Fig. 5 einen Halbschnitt ähnlich dem nach Fig 4, jedoch in der Preßstellung, wobei eine Drehung um 90° gegenüber Fig. 4 vorgenommen ist, um einige Teile deutlicher zu machen; und in
• Fig. 6 einen den Fig. 4 und 5 entsprechenden Halbschnitt, jedoch in Abzugs- bzw. Ausstoßstellung.

The drawings show in

• Figure 1 is a vertical section through the parts located between the upper and lower bears of the press.
• Fig. 2 is a section substantially along the line II-II of Fig. 3;
• Fig. 3 is a section along the line III-III of Fig. 1;
• Fig. 4 is a half section substantially corresponding to that of Figure 3 with the press tools used to produce a multi-stage workpiece in the filling position.
• Fig. 5 is a half section similar to that of Figure 4, but in the pressing position, wherein a rotation of 90 ° compared to Figure 4 is made to make some parts clearer. and in
• Fig. 6 is a half section corresponding to Figs. 4 and 5, but in the trigger or ejection position.

In Fig. 4 the representation of the intermediate plate and the base plate has been rotated by 90 ° in order to make otherwise invisible parts visible.

1, the lower coupling plate 1 is coupled via a connector 2 with a T-piece 3, which is part of the machine frame. The lower coupling plate 1 is firmly connected to a die holding plate 5 via the tie rods 4. The connector 6 is inserted on the movable part, ie on the upper punch of the press and with the upper one Coupling plate 7 connected so that it is connected in this way to the upper punch of the press.

The upper coupling plate 7 is slidably guided in the die holding plate 5 via guide rods 8. On the way from the filling position (FIG. 4) to the pressing position (FIG. 5), the guide rods penetrate the mounting plate 9 through openings which are kept correspondingly large. The receiving plate 9 receives one or more stamps. 4 to 6, the stamp 10 is fastened to the mounting plate 9 via a bridge 11 with the aid of a retaining ring 12. 3, piston rods 13 are fastened to the mounting plate 9, the pistons 14 of which can be displaced in the hydraulic cylinder 15 in the base plate 16. On the base plate 16 sit guide sleeves 17, which have a thread 18 at their upper end, on which a cap 19 with an internal thread is placed, the adjustment of which on the thread 18 enables the setting of the press end position. A further punch 22 sits on an intermediate plate 20 over a bridge 21 similar to bridge 11, which is also fastened to bridge 21 with the aid of a retaining ring 23. In the base plate 16, which is fixed with respect to the press, there are, as can be seen from FIG. 1, a further two cylinders 24, in which pistons 25 are arranged, which are guided with their piston rod 26 in a cylindrical guide element 27 which is similar to the guide cylinder 17 and as this has a thread 28 on which a cap 29 with an internal thread is arranged. The piston 26 is fixed in the intermediate plate 20. The rotatable cap 29 thus, like the rotatable cap 19, enables the end position of the press to be changed.

According to FIG. 3, a further piston 30 is arranged in the base plate 16 and is displaceable in a cylinder 31. This piston 30 is designed as a hollow piston and has a central opening 32 through which an element to be explained later will be passed. On the base plate 16 there is a further guide element 33 with a thread 34, on which a rotatable cap 35 with an internal thread is arranged, which serves for changing the press end position of the piston 30, which is displaceable in the cylinder 31. The stop takes place with the aid of a receiving plate 36 which is fixedly arranged on the piston rod 37 of the piston 30.

4 to 6, an extension piece 39 is seated on the receiving plate 36, on which a further punch 41 is fixed with the aid of a retaining ring 40. In the exemplary embodiment shown, the stamp 41 is the innermost stamp. Of course, the three-part stamp arrangement in the exemplary embodiment can be extended or reduced, while maintaining this principle, into a stamp arrangement with more or less than three stamps, or can be selected so that the gradation on the molded body 42 (FIG. 6), which is obtained from the filled-in molding compound 43 ( Fig. 4) is produced, vice versa, ie runs from the inside out. Any other structure, insofar as it can be reached with stamps, can be realized according to this principle.

On the lower coupling plate 1, a central pin 44 is fastened directly or with the aid of a collar 45 (FIGS. 4 to 6). Then it moves with the coupling plate 1. The center pin 44 continues upwards until it is flush with the die holding plate 5. The central pin 44 can, however, also pass freely through the opening 47 in the lower coupling plate 1 and be coupled to a piston 48 which can be actuated in a hydraulic cylinder 49 which is arranged in the T-piece 3. This means that it can be moved independently of the movement of the die holding plate 5.

A scale 52 is provided for the piston 30 in the cylinder 31, which slides in a bore 53 in the base plate 16. The scale 52 is firmly attached to the piston 30 and thus follows its movement. The scale 52 allows any measurement of the path of the associated piston 30 relative to the base plate 16, so that it is possible to electronically evaluate the determined value and to supply it to a corresponding control device. With each path length unit, for example 1 / 100th of a millimeter, the scale triggers a pulse in the electronic control, the machine being controlled for the next locomotion after a certain pulse quantity has been reached. In the exemplary embodiment, this next movement consists in the relative movement between the base plate 16 and the intermediate plate 20 and is tracked with the aid of the measuring rod 54, which dips into the bore 55 in the intermediate plate 20. Then the relative movement between the base plate 16 and the mounting plate 9 is scanned with the aid of the scale 56, which plunges into the bore 57 in the mounting plate 9. If, as indicated above, the center pin 44 is coupled to the piston 48, it can also be brought into any desired position relative to the die holding plate 5 by means of a scale (not shown) and this at a preselected speed. It can be used to influence the powder flow regardless of temperature changes and friction conditions. This solves the problem that results from the fact that the punches 10, 22 and 41 and the central pin 44 heat up in the course of the sequence of the pressing processes and the frictional relationships between the molded body and them change during the compression process and thus to an uncontrollable powder flow with resulting changes in density in the pressed molded body. This can now be done by a regulated movement the stamp and the center pin from the filling to the pressing position can be successfully counteracted.

4 to 6 can also be seen the upper counter-punch 58 fastened to the upper coupling plate 7, which is so far from the die 59 stored in the die-holding plate 5 during the filling process, the end of which is shown in FIG. 4, that the filling device, not shown, generally designed as a filling slide, can be moved in and out between the upper counter-punch 58 and the die. The upper counter-punch 58 partially moves into the die 59 during the pressing process, the end of which is shown in FIG. 5.

Claims (12)

1. An upper bear and a lower bear press for the production of dimensionally stable compacts from powdery material with a base plate, a die plate and a lower punch, which is hydraulically displaceable relative to the base plate and the die holder plate, the base plate and the die holder plate being parts of a die holder plate and a lower one Coupling plate are connected by means of tie rods, which is connected to the upper bear via a connecting piece which can be displaced in the pressing direction relative to the framework, while the lower bear of the press is connected to the lower coupling plate, characterized in that lower parts (10, 22, 41) carrying machine parts ( 9; 11; 20, 21; 36) are mounted opposite the base plate (16) via hydraulic cylinder-piston systems (13, 14, 15; 24, 25, 26; 30, 31, 37) in the pressing position with respect to of the press frame fixed stops (19, 29, 35) and after to eject the compact Removal of the die (59) after the surfaces of the compact which are in contact with the die (59) are released and can be raised step by step until the next contact surface is released. 2. Press according to claim 1, characterized in that the stops (19, 29, 35) are adjustable. 3. Press according to claim 2, characterized in that the stops consist of caps (19, 29, 35) which are screwed onto threads (18, 28, 34) on the ends of guide sleeves (17, 27, 33). 4. Press according to one or more of the preceding claims, characterized in that the machine parts consist of plates (9, 20, 36) which on the Piston rods (13, 26, 37) of the hydraulic cylinder-piston systems are attached. 5. Press according to claim 4, characterized in that each plate (9, 20, 36) is assigned a fixed to the base plate (16) measuring member (52, 54, 56) which acts as a path scanner for the path of the plates (9, 20, 36) serves in the filling and ejection position. 6. Press according to claim 5, characterized in that the measuring elements have the shape of scales (52, 54, 56) which are in bores (53, 55, 57) in the base plate (16), in the intermediate plate (20) or engage in the mounting plate (9). 7. Press, in particular according to one or more of the preceding claims, characterized by a central pin (44) which moves the die holding plate (5) and which is freely controllable in its speed relative to the die holding plate (5). 8. Press according to claim 7, characterized in that the central pin (44) on the piston (48) of a hydraulic cylinder (49) is fixed, which is coupled to the lower coupling plate (1). 9. A method of operating the press according to one or more of the preceding claims, characterized in that after removing the die from the compact, the individual lower punches sitting on the machine parts after release of the pressed molding by the enveloping shaping surface step from the previous punches, always together in this way be raised far enough until another surface level is exposed. 10. The method for operating the press according to one or more of claims 1 to 6, characterized in that the speed of the individual machine elements carrying the lower punches are driven independently of one another from the start of the pressing process. 11. The method according to claim 10, characterized in that the machine elements are driven in their speed depending on the build-up between the upper punch and the individual lower punches in the material to be pressed into their final pressing position. 12. The method according to claim 9, 10 or 11, characterized in that the movement of the ram is controlled by control electronics.

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