EP1849590B1 - Press - Google Patents

Description

The invention relates to a press for producing dimensionally stable compacts of powder material according to claim 1.

Presses for the production of dimensionally compact compacts of powder material basically have a die, at least one upper and at least one lower punch, which compress the powder material in the cavity of the die from opposite sides. Upper and lower stamp are z. B. connected to the plunger or the piston rod of a hydraulic cylinder, which are mounted on the press frame. The powder material is introduced into the die bore with a suitable filling device, the position of the lower punch normally defining the filling level or the filling volume. After pressing the material, the compact is removed from the die bore.

In such presses different designs are used. With so-called one-sided presses, the lower punch and the die are fixed. For double-sided presses, the die is either floating or forcibly moved with a fixed or movable lower punch. For the removal of the compact either the so-called ejection method or the withdrawal method is used. In the ejection process, the compact is moved out of the stationary die with the aid of the lower punch, while in the withdrawal process the lower punch is fixed and the die is moved.

The pressing tools are usually not attached directly to the hydraulic adjusting drives, but via so-called. Adapters. For example, the die is mounted on a die holding plate, which - if movable - in turn is connected by means of force transmission elements with an adjustment. The same applies to upper and lower punches, which are attached to corresponding holding plates. As a result, different pressing tools can be installed in an existing press.

A press is designed in the prior art according to which Entungsungsprinzip is applied. A conversion to the other demolding principle is therefore usually not considered.

To control or control a pressing operation, the knowledge of at least two parameters is important. First, the pressing force is measured to determine the maximum force with which the powder is compressed. Optionally, the Preßkraftverlauf the tools over the way or over time during the pressing process is helpful. Another parameter is the position of upper and lower punches with respect to a reference, which is usually formed by the upper edge of the die. Known, it comes by temperature influences and the pressing forces to length changes of the press frame, the power transmission elements and the tools. With the help of suitable measuring systems, the position of the tools on their adapters can indeed be measured, without a correction over the respective temperature and pressing force, the position determinations are not sufficiently accurate enough. In addition, there is a risk that the measuring systems themselves or their attachment suffer temperature-dependent and compressive force-dependent deformations and therefore carry inaccuracies in the measurement.

Out DE 102 54 656 B4 a typical hydraulic press has become known in which a die holding plate and a plurality of stamp carriers (adapters) are mounted in the press frame so as to be adjustable via hydraulic drives. In the known press support devices are provided which support the punch carrier in press end position relative to the main body of the press frame. Out DE 3142126 B1 is a press for the production of stepped dimensionally pure Pulverpreßlingen made of ceramic material known in the lower punch bearing receiving plates are all hydraulically movable from a base plate and sit in the press end position as receiving plates on adjustable mechanical stops of the base plate. The receiving plates are for ejecting the compacts after removal of the die and free coming into contact with the die in contact surface of the compact together in each case until the coming of the next contact surface gradually hochfahrbar. In the press end positions formed by fixed stops, the counterforce or support force is formed by mechanical stops in both presses.

Out DE 103 00 722 B3 has become known a press in which an upper and a lower carriage for the attachment of an upper and lower punch on a guide column are guided vertically. The guide column is attached to a frame table on which the die holding plate is mounted. A wear-free guidance of the holding plates takes place in that via an angle compensation element and a lateral compensation element is a connection of the carriage to the hydraulic drive.

Out JP-A-05057497 a press according to the preamble of claim 1 has become known with two linear measuring systems which are mounted on a rod, which in turn is attached to a die plate. The two measurement systems allow adulterants to add or subtract from thermal influences. Mutual influence is not excluded. Since the rod is connected to the press frame, it is also exposed to the thermal effects of the press frame.

Out JP-A-04111999 a separate guide for a punch plate is disclosed in a press. The guide is coupled in the vertical direction of the press frame. A position measurement of retaining plates is not disclosed.

Out DE-A-10318832 For example, there has been known a die height adjusting device for a press in which a carriage connected to the die plate entrains a measuring ruler, while a position sensor moved along the measuring ruler is fixedly connected to a frame-fixed base plate. The ruler is attached to a bracket that is decoupled from the press position.

The invention has for its object to provide a press for producing dimensionally stable compacts of powder material, which allows the lowest possible position determination of the tools.

This object is solved by the features of patent claim 1.

In the press according to the invention a holder for a single measuring ruler in the vertical direction is decoupled from the press frame. Thus, a relative movement between the press frame and holder is possible, causing thermally and by pressing forces caused changes in length of the press frame no length changes of the holder. The measuring ruler is e.g. attached to a decoupled from the press frame vertical guide for the holding plates. Although the holder or the vertical guide has its own thermally induced changes in length, these must be taken into account in the measured position values, changes in length of the press frame, however, in particular due to compressive forces, on the other hand have no effect on the measuring ruler. The distances of the holding plates are also largely without significant temperature influences.

It is advantageous if according to an embodiment of the invention, the measuring ruler is fixed only in the amount of a reference plane for the pressing tools, for example, in the amount of a clamping surface for the die on the die support plate. The thermal fixed point is naturally in the middle of a length measuring system. If several of these are provided, there will be a change in direction of the linear expansion when the measuring slide passes through this fixed point. In the invention, only one fixed point is provided, namely in the reference plane. As a result, thermal expansions of the vertical guide do not affect interfering with the measuring ruler, so that only thermal expansions of the ruler itself are to be considered.

The measuring system according to the invention can be used for different operating modes of a press, regardless of whether the ejection or exhaust method is used.

As mentioned, in the invention, a special arrangement of the vertical guide is provided. In the invention, the vertical guide is formed by a vertical guide column, which is arranged eccentrically with respect to the Hauptpreßachse in the press frame and having two parallel vertical guide tracks for holding plates.

For the arrangement of the guide column, the invention provides that the lower end of the guide column is fastened together with a lower adjustment on the press frame and fixed in all directions and the upper end of the guide column is fixed only in the horizontal direction on the press frame, while vertical relative movements of guide column and press frame are allowed. The guideways are formed according to a further embodiment of the invention of preferably parallel in cross-section dovetail guide rails which are fixed to the one-piece guide column and guided on the guide rails carriages, with each of which a support plate is connected.

Since no forces are to be transmitted from the holding plates on the guide column, the alignment of the axes of the guided holding plates is desirable. Therefore, an embodiment of the invention provides that the upper adjustment sits positively in an upper bearing plate, which in turn is bolted to an upper connecting plate of the press frame. An alignment plate is connected to the upper end of the guide column,

and bearing plate and alignment plate have a positive connection such that they are only horizontally fixed to each other. Of the plate have a positive connection such that they are only horizontally fixed to each other. The lower adjustment drive sits positively in a lower bearing plate and the guide column is based on this bearing plate. Now, if a connection of the alignment plate with the upper bearing plate by the positive engagement, it is automatically an orientation of the axes of upper and lower bearing plate and thus given by upper and lower punch. Bearing plate and alignment plate preferably have at least one pair of aligned bores, each receiving a dowel.

Holding plates, tools, vertical guide and measuring ruler are naturally subjected to elongations as a function of the prevailing temperatures. For an exact measurement of the position of the lower and upper punches or of the die, therefore, these heat-related changes in length must be taken into account. A direct measurement of the upper end of the lower punch or the lower end of the upper punch is naturally excluded. Their position can therefore only be determined by the position of the holding plates. An embodiment of the invention provides that the pressing tools and / or the holding plates and / or the vertical guide and / or the measuring ruler are associated with temperature sensors and a computer is provided, in which the position signals of the ruler and the measuring signals of the temperature sensors are input and the computer taking into account the coefficients of thermal expansion of the materials for the parts detected in their temperature, lengths and thus the position values of the pressing tools are corrected in accordance with the temperature values.

The pressing force also deforms the pressing tools. It is therefore advantageous according to an embodiment of the invention, when measured by means of Kraftmeßgliedem, the forces exerted on the pressing tools forces and the measured values are given in the computer. The calculator corrects as required the spring core lines of the pressing tools the measured values with the measuring ruler.

Fig. 1

zeigt perspektivisch den Aufbau einer Lagerung der Halteplatten für eine Hydraulikpresse ohne Pressengestell und Hydraulikantriebe nach der Erfindung,

Fig. 2

zeigt schematisch einen Schnitt durch den Aufbau nach Figur 1 mit einer Andeutung des Pressengestells und der oberen und unteren Hydraulikantriebe,

Fig. 3

zeigt schematisch die Draufsicht auf die Anordnung nach Figur 2,

Fig. 4

zeigt schematisch eine ähnliche Darstellung wie Figur 2 mit einem Positions-Meßsystem,

Fig. 5

zeigt die Ansicht der schematischen Anordnung nach Figur 4 in Richtung Pfeil 5,

Fig. 6

zeigt schematisch die Positionsbestimmung der Preßwerkzeuge nach Fig. 2.

The invention will be explained in more detail below with reference to an exemplary embodiment:

Fig. 1

shows in perspective the structure of a mounting of the holding plates for a hydraulic press without press frame and hydraulic drives according to the invention,

Fig. 2

schematically shows a section through the structure according to FIG. 1 with an indication of the press frame and the upper and lower hydraulic drives,

Fig. 3

schematically shows the top view of the arrangement according to FIG. 2 .

Fig. 4

schematically shows a similar representation as FIG. 2 with a position measuring system,

Fig. 5

shows the view of the schematic arrangement FIG. 4 in the direction of arrow 5,

Fig. 6

schematically shows the position of the pressing tools after Fig. 2 ,

In Fig. 1 a bearing plate 10 can be seen, on which a guide column 12 is supported by a substantially rectangular or square cross-section. The guide column 12 is preferably formed in one piece and may also be integrally formed with the bearing plate 10.

On one side of the guide column 12, two parallel guide rails 14, 16 are mounted, preferably by means of screw, which are dovetailed in cross-section. The vertical parallel guide rails 14,16 store guide carriages 18, 20, 22, 24, 26, 28 and 30, 32 which are horizontal, axial spaced holding plates 34 to 40 are mounted. The holding plates are constructed substantially the same and have T-shape in section. The upper holding plate 34 is used for clamping a top punch (not shown), the holding plate 36 is a die holding plate and is used for clamping a die, and the lower holding plates 38, 40 are used for clamping Unterstempeln. The holding plates 34 to 40 can with a in FIG. 1 not shown upper and lower hydraulic drive are coupled for the purpose of vertical adjustment along the guide rails 14, 16. This will be discussed below. The lower holding plates 38, 40 have openings 42, 44 for the passage of power transmission elements of a lower hydraulic drive to the respective overlying holding plate, ie in the present case the die holding plate 36 and the holding plate 38th

At the upper end of the guide column 12, a horizontal alignment plate 46 is fixed, which has two holes 48 near the free end.

On the in FIG. 1 right side of the guide column 12, a measuring ruler 47 is mounted, slide on the Meßschlitten 48, 50, 52, 54. The measuring carriages 48 to 54 are each coupled to a holding plate 34 to 40. With the help of the measuring slide 48 to 54 and the measuring ruler 47, the position of the holding plates 34 to 40 is determined and thus the position of the pressing tools, not shown.

In FIGS. 2 and 3 is the arrangement of in FIG. 1 shown unit indicated in a press frame.

How out FIGS. 2 and 3 shows a press frame four square, vertical support columns 56, which are connected to each other in the upper region by an upper connecting plate 58 and in the lower region by a connecting plate 60. The connecting plates 58, 60, which extend horizontally, have circular openings 62 and 64, respectively.

The lower bearing plate 10 has a circular opening 66 in which a lower hydraulic drive 68 is positively inserted. The bearing plate 10 is screwed into the opening of the connecting plate 60. The guide column 12 is supported on a radial projection 70 of the bearing plate 10 and is screwed thereto. In the FIGS. 2 and 3 in each case only one holding plate is indicated, for example, the holding plate 38 for a lower punch. An upper bearing plate 72 positively receives an upper hydraulic drive 74. The bearing plate 72 can be screwed into the recess of the upper connecting plate 58. The bearing plate 72 has two bores, one of which is shown at 76. They are aligned to the holes 48 of the alignment plate 46. Through the pair of holes dowel pins can be inserted, of which one at 78 in FIG. 2 is shown. This makes it possible to position the bearing plate 72 horizontally with respect to the alignment plate 46 and thereby also bring the axis of the upper hydraulic drive 74 in alignment with the axis of the lower hydraulic drive 68, whereby a common vertical axis 73 is achieved. In the vertical direction can be allowed between the guide column 12 and the frame, here represented by the columns 56 and the connecting plates 60, 58, a relative movement.

In the FIGS. 4 and 5 is the arrangement after FIG. 2 indicated schematically. With FIG. 2 are equal parts in the FIGS. 4 and 5 provided with the same reference numerals. It can also be seen a die 102 on the die support plate 36, an upper punch 104 on the upper support plate 34 and a lower punch 106 on the lower support plate 38. Upper and lower punches 104, 106 cooperate with the die 102.

The pressing tools are in the FIGS. 4 and 5 shown in a referencing position, wherein the upper edge of the die 102 is relevant for the referencing. Referencing sets the tool zero point of the system. Other tool parts refer to this zero point. The thermal reference plane is the clamping plane of the support plate 36 for the die 102, ie the top of the die support plate 36, with which the Meßschlitten 50 cooperates. In this plane, the measuring ruler 47 is fixed to the column 12 at 108, and only in this plane.

The measurement of the tool lengths is not immediately possible, but - as mentioned - on the holding plates 34 to 38. Therefore, the temperature that is measured during referencing, must be included. A temperature measurement takes place at the points labeled "T", i. on the holding plates 34 to 38, upper punch 104 and lower punch 106 and also in the die 102. When measuring the tool lengths 1 during operation, therefore, the value determined during referencing must be drawn into the measured temperature. In addition, in pressing forces occur length changes, which are measured by means of load cells, sensors or the like. These values must also be taken into account for correcting the respective tool positions.

In order to be able to stir through the described operations, a computer is required in which the signal values measured by the measuring ruler 47 as well as the temperature values and force values are entered in order to calculate the respective actual lengths 1 for determining the position of the tools.

In terms of FIG. 5 remains nachzutragen that on opposite sides support members 120, 122 are provided, which are supported on the plate 10 and in turn support the die support plate 36 mechanically. They are arranged so that they can be rotated about a vertical axis to be positioned below or below the die support plate 36. If the die holding plate for the ejection method is stationary, the support members 120, 122 take the in FIG. 5 shown position. In the withdrawal method, however, the die holding plate 36 is movable.

In FIG. 6 a control computer 126 is indicated, in which the temperature values T are input by the individual sensors. In addition, individual pressing force values P, which are measured by Preßkraftmeßgliedern not shown, entered into the computer 126. The measuring signals of the measuring carriages 48, 50 and 52 are finally fed into the computer on the measuring ruler 47, which determines the individual positions of the pressing tools by means of the lengths 1 for lower and upper punches 104, 106 and the die 102 taking into account the temperature values and the pressing force values. by which the length values have to be corrected. After action of the corrected length values, corresponding position values P _OS , P _M and P _US for the press tools are then determined for the purpose of controlling the hydraulic cylinders for the press tools. In FIG. 6 only the outputs for an upper and a lower hydraulic cylinder are indicated by HZ _O and HZ _U.

Claims (9)

1. Press for producing dimensionally stable pressed parts from powdered material, with a press frame, a die holding plate holding the die spanned, at least one upper punch holding plate, at least one lower punch holding plate, adjusting drives for the upper punch and lower punch holding plate and/or die holding plate, a vertical guide in the press frame for at least the upper and lower punch holding plate and a measuring device for measuring the position of the upper punch holding plate, the lower punch holding plate and/or the die holding plate on which guide carriages are arranged, characterised in that the vertical guide is formed by a vertical guide post (12) which is arranged eccentrically in the press frame and comprises two parallel vertical guide tracks for the holding plates,
   the lower end of the guide post (12), together with a lower adjusting drive (68), is fastened to the press frame and is secured in all directions and the upper end of the guide post (12) is only secured in the horizontal direction to the press frame, whilst vertical relative movements of the guide post (12) and the press frame are allowed.
2. Press according to Claim 1 or 2, characterised in that the measuring rule (47) is only fastened on the vertical guide at the height of a reference plane (108) for the press tools (104, 102, 106).
3. Press according to Claim 2, characterised in that the reference plane is the clamping surface of the die holding plate (36) for the die (102).
4. Press according to one of the Claims 1 or 3, characterised in that the guide tracks are formed by dovetail-shaped guide rails (14, 16) which are preferably parallel in cross section and which are fastened to the one-piece guide post (12) and guide carriages (18 to 32) are guided on the guide rails (14, 16), to which one respective holding plate (34, 36, 38, 40) is connected.
5. Press according to one of Claims 1 to 4, characterised in that the upper adjusting drive (74) is located positively in an upper bearing plate (72), which in turn is screwed to an upper connecting plate (58) of the press frame, and is connected to the upper end of the guide post (12) of an alignment plate (46), the bearing plate (72) and the alignment plate (46) being able to be secured to one another horizontally by a positive connection, the lower adjusting drive (68) being located positively in a lower bearing plate (10) and the guide post (12) being supported on the lower bearing plate (10).
6. Press according to Claim 5, characterised in that the upper bearing plate (72) and alignment plate (46) comprise at least one pair of bores (76, 48) which may be aligned with one another for receiving a locating pin (78).
7. Press according to one of Claims 1 to 6, characterised in that frame posts (56) span a rectangle, preferably a square, and the guide post (12) is arranged in a corner region of the rectangle and/or square on the inner face of an associated frame post (56).
8. Press according to one of Claims 1 to 7, characterised in that temperature sensors are associated with the press tools (104, 102, 106) and/or the holding plates (34, 36, 38) and/or the vertical guide and/or the measuring rule (47) and a computer (126) is provided into which the position signals of the measuring rule (47) and the measuring signals of the temperature sensors are entered and, by considering the coefficients of thermal expansion of the materials for the parts of which the temperature is recorded, the computer (126) corrects the position values and/or the length values of the press tools (104, 102, 106) according to the temperature values.
9. Press according to Claim 8, characterised in that by means of force measuring elements the forces exerted on the press tools (104, 102, 106) are measured and entered into the computer (126), and the computer corrects the position and/or length values measured by the measuring rule (47) according to the spring characteristics of the press tools (104, 102, 106).

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