EP0320747B1 - Pellet press - Google Patents

Abstract

A pellet press has a hollow cylidnrical pressing mould (9) which is provided with essentially radial bores and on the inner circumferential surface of which at least one pressing roller (9a), arranged eccentrically in relation to the latter, is arranged rollably. To fasten this pressing mould (9) to a press-side mould support (10), a holding device is provided, which has at least one of the following groups of characteristics: a) that there is provided indirectly or directly in the mould support (10) on the inner rotation surface at least one essentially radially fluid-actuable fixing member, e.g. a diaphragm (43), which can be brought to bear against the outer rotation surface (44) of the mould (9); b) that the mould (9) is provided on at least one of its end surfaces with at least one undercut opening (22), and that a fixing member (23a) reaching into the opening (22) is rotatable, with a grip surface (23) projecting at an angle to a longitudinal axis, by means of an in particular fluid-actuated actuating device (25 - 32), by a predetermined angular amount, at which the grip surface (23) grips the undercut of the opening; c) that there are provided indirectly or directly on the mould support (10) and the mould (9) concentric, in particular self-locking threads (52) which engage in one another. <IMAGE>

Description

The invention relates to a pellet press, according to the preamble of claim 1, as used for example for animal feed and other materials to be pressed.

With pellet presses, different press molds must be used depending on the material to be processed and the intended use. In general, either several, distributed over the circumference screws for immediate fastening or clamping rings are used to attach the molds to a mold carrier, which in turn are fastened to the mold carrier with the aid of screw bolts. This means that when installing the press mold, care must first be taken to ensure that the press mold and mold carrier are brought together with exactly the same axis, after which the various screws must be tightened evenly. Naturally, this requires a not inconsiderable amount of work.

The fact is, however, that for smaller batches, the molds have to be changed relatively frequently, so that it is desirable to shorten this process. Now, due to the circumstances (dimensions and weight, wear), a perfect form fit between the mold and the mold carrier is difficult to achieve. It is even more difficult to maintain it even during operation, since the temperature difference between a cold and new one clamping mold to be clamped and the mold carrier heated by the operation can lead to considerable dimensional differences which only balance out when the temperature of the two parts is adjusted. In addition, there are the vibrations that are unavoidable during operation, which can lead to a loosening of the connection, and possibly even to breakage of the press mold.

Although the form fit can be improved if the compression mold and / or the mold carrier or a part connected to it have a conical surface, this presupposes an exact, axially parallel insertion of the two conical parts. In general, this will be difficult given the high weight of the dies, so there is a risk of canting. Such constructions can be found in FR-A-1 115 893 and US-A-4 022 563 and 4 226 578. However, if this also improved the form fit, the axially parallel, tilt-free installation was by no means guaranteed. Furthermore, a lot of work was still required to secure the press mold with the help of screw bolts.

The invention has for its object to provide a pellet press in which the molds can be changed quickly, safely and with little effort. According to the invention, this is achieved by the characterizing features of claim 1.

The implementation of at least one of the features according to a), b) and c), but in particular the combination of at least two of these features, results in a particularly simple and quick to implement assembly of the mold on the mold carrier.

Are essentially radially fluid-actuated locking elements, e.g. If a membrane is provided, a clamp fit with or without a form fit can be realized particularly easily, with sufficient force transmission between the mold carrier and the form being ensured even under the unfavorable conditions described above (temperature and dimension differences, flexing of the form and vibrations).

If the shape is provided on at least one of its end faces with at least one undercut opening into which a rotatable locking element engages in such a way that it detects the undercut of the opening in a position rotated by a predetermined angular amount with a gripping surface, this also results in a simple manner flawless form fit between the mold and the mold carrier, whereby dimensional changes are easily compensated for. The locking elements also serve as aids when mounting the mold on the mold carrier.

If threads are arranged on the mold or on the mold carrier, the mold can be fastened to the mold carrier by a simple rotary movement, for example by the drive motor for the mold, the thread simultaneously serving as a retraction device for the mold against the mold carrier and centering backs up. The combination of these features makes it possible to achieve a pellet press that is particularly easy to operate and is designed in accordance with the technical requirements.

Preferably, the axially and / or radially fluid-actuated locking members are arranged so as to act in a distributed manner on the circumference of the mold, which results in the required centering.

According to the invention, at least one pressure accumulator can be provided in the fluid line for the locking members, whereby an advantageous pressurization is achieved even when there is no connection to the pressure generator, e.g. a hydraulic pump or a compressor, so that a fluid supply through the rotating mold carrier is not necessary during the operation of the pellet press.

According to a further feature of the invention, the holding device is at least one fluidic actuating device with a piston Assigned cylinder unit, via which a separate stamp with piston, which is arranged in a hydraulic cylinder, can be actuated, and / or the locking element, which can be fluidly actuated in one actuation direction, is in the other direction by at least one, in particular mechanical spring device, for example by Disc springs, preferably in the direction of the stop position, acted upon. This enables an independent movement of the plunger or the locking element, so that a linear movement by means of the piston-cylinder unit or the spring device can also be converted into a helical movement, for example. The, in particular mechanical, spring device also ensures the function of the pellet press in its working position even if the fluid circuit fails completely, if the locking element is acted upon by the spring device in the direction of the holding position.

Correct centering between the mold and the mold carrier is achieved if, according to the invention, the outer rotational surface of the mold is designed as a cone which can be inserted into a counter cone of the mold carrier which forms the inner rotational surface, possibly as a separate ring in this. The respective radially actuatable locking element is expediently designed as a membrane that can be pressed against the external rotation surface of the mold.

• a) einen im wesentlichen rechteckigen, beidseits vom Schaft abstehenden Kopf,
• b) ihm ist eine Betätigungsvorrichtung für Axialbewegung zugeordnet, wobei seine Drehbewegung über eine Drehführung erfolgt, wobei vorzugsweise die Drehführung einen Vorsprung, insbesondere einen Stift, z.B. am Kolben, aufweist, welcher in einer schraubenförmigen Nut, z.B. in einem Führungszylinder, führbar ist und zweckmässig die Nut an ihren beiden Enden Raststellungen, insbesondere parallel zur Achsrichtung verlaufende Endteile, aufweist.

An advantageous embodiment is obtained when at least one locking element, in particular all, which can be rotated by a predetermined angular amount, has at least one of the following features:

• a) a substantially rectangular head which projects from the shaft on both sides,
• b) an actuating device for axial movement is assigned to it, its rotary movement taking place via a rotary guide, the rotary guide preferably having a projection, in particular a pin, for example on the piston, which can be guided and expediently in a helical groove, for example in a guide cylinder the groove has latching positions at its two ends, in particular end parts running parallel to the axial direction.

The rotatable locking member can be used to easily center the mold on the mold carrier.

• a) die Feststellung ist bei einer Relativdrehung der Gewindeteile von 15" bis 100" erreichbar,
• b) das Gewinde ist konisch,
• c) das Gewinde ist mehrgängit,
• d) an der Form und/oder am Formträger, vorzugsweise auf letzterem, sind, bezogen auf den Umfang, in einem Abstand voneinander angeordnete Gewindesegmente vorgesehen, wobei vorzugsweise die Anzahl der Gewindesegmente gleich der Anzahl der Gänge des mehrgängigen Gewindes ist,
• e) das Gewinde der Form und/oder des Formträgers, vorzugsweise des letzteren, ist in Axialrichtung elastisch, insbesondere über Tellerfedern, befestigt,
• f) es ist an zumindest einem Gewindering vorgesehen ist, der mit der Form bzw. dem Formträger, vorzugsweise mit ersterer, lösbar, insbesondere über Schrauben, verbunden,
• g) die Arbeitsdrehrichtung des Formträgers ist im Sinne eines Einschraubens der Gewinde gewählt,
• h) die Form ist mit einer Hebeeinrichtung, z.B. Flaschenzug, verbindbar, die eine Druckmesseinrichtung, z.B. Dehnmessstreifen, aufweist, über welche ein Gewindeservormotor für eine Relativverdrehung der Gewindeteile steuerbar ist,
• i) das an einem Gewindering ausgebildete Innengewinde des Formträgers ist aussen zumindest teilweise mit einer Verzahnung versehen, über welche der im Formträger zumindest teilweise drehbar gelagerte Gewindering zu einer Drehung antreibbar ist, wobei zweckmässig in die Zähne des Gewinderinges ein Zahnritzel oder eine Schnecke eingreift,
• k) das an einem zumindest teilweise drehbar gelagerten Gewindering ausgebildete Innengewinde des Formträgers weist zumindest eine periphere Auzsnehmung auf, die sich parallel zu einer Tangente an dem Gewindering erstreckt, an welcher ein Drücker, insbesondere ein Schraubbolzen, abstützbar ist,
• I) das an einem Gewindering ausgebildete Innengewinde des Formträgers ist, gegebenenfalls teilweise drehbar, mit axialem Spiel im Formträger gelagert, wobei zweckmässig entweder der Gewindering über Schraubbolzen, verzugsweise federnd, insbesondere mit Tellerfedern, an dem Formträger gehalten ist und/oder der Gewindering über zumindest einen in Axialrichtung, z.B. über wenigstens eine Zylinder-Kolbenaggregat oder über mindestens eine Drehspindel, betätigbaren Drücker beaufschlagbar ist, wobei insbesondere mehrere Drücker über den Umfang verteilt sind und gegebenenfalls gemeinsam, z.B. über eine Kette betätigbar sind.

A plurality of undercut openings is expediently distributed over the end face of the mold, in particular formed on a circumferential rail fastened to the mold, which can be inserted into a corresponding recess in the carrier. This enables a uniform contact pressure to be achieved. If threads are arranged on the mold carrier and on the mold, at least one of the following features is preferably provided:

• a) the determination can be achieved with a relative rotation of the threaded parts from 15 "to 100",
• b) the thread is conical,
• c) the thread is multi-thread,
• d) on the mold and / or on the mold carrier, preferably on the latter, there are thread segments arranged at a distance from one another in relation to the circumference, the number of thread segments preferably being equal to the number of threads of the multi-start thread,
• e) the thread of the mold and / or the mold carrier, preferably the latter, is fastened elastically in the axial direction, in particular by means of disc springs,
• f) it is provided on at least one threaded ring which is detachably connected to the mold or the mold carrier, preferably to the former, in particular by means of screws,
• g) the working direction of rotation of the mold carrier is selected in the sense of screwing in the thread,
• h) the mold can be connected to a lifting device, for example a block and tackle, which has a pressure measuring device, for example strain gauges, by means of which a threaded servo motor can be controlled for a relative rotation of the threaded parts,
• i) the internal thread of the mold carrier, which is formed on a threaded ring, is externally at least partially provided with a toothing, by means of which the threaded ring, which is at least partially rotatably mounted in the mold carrier, can be driven to rotate, a toothed pinion or a worm meshing expediently in the teeth of the threaded ring,
• k) the internal thread of the mold carrier, which is formed on an at least partially rotatable threaded ring, has at least one peripheral recess which extends parallel to a tangent to the threaded ring, on which a pusher, in particular a screw bolt, can be supported,
• I) the internal thread formed on a threaded ring of the mold carrier is, if necessary partially rotatable, mounted with axial play in the mold carrier, wherein expediently either the threaded ring is held on the mold carrier via screw bolts, preferably resiliently, in particular with disc springs, and / or the threaded ring is held over at least a pusher which can be actuated in the axial direction, for example via at least one cylinder-piston unit or via at least one rotary spindle, can be acted on, in particular a plurality of pusher are distributed over the circumference and optionally together, for example can be operated via a chain.

With a relative rotation of the threaded parts from 15 "to 100", a particularly simple and quick assembly of the mold on the mold carrier is possible. If the thread is designed as a conical thread, the thread itself can already serve as an essentially conical fitting surface, with particularly high forces being able to be transmitted. Such threads are used, for example, for prospecting and production lines in the petroleum industry. The arrangement of the threaded segments arranged at a distance from one another makes it possible to measure their spacing in such a way that the threaded segments of the other part of the mold carrier or of the mold can be inserted axially and then rotated. With a connection of this type, particularly high forces can be transmitted between the mold and the mold carrier, a positive connection being able to be achieved by a small angular rotation. If the threaded ring is detachably connected to the mold or the mold carrier, the parts subject to wear can be exchanged in a simple manner. If the working direction of rotation of the mold carrier is selected in the sense of screwing in the thread, a particularly trouble-free connection between the mold and the mold carrier is possible, since loosening of the mold during its rotation is impossible.

• a) dass über eine Kupplung wahlweise ein Antriebsmotor für Direktantrieb von seiner Motorwelle aus oder über ein Reduziergetriebe mit dem Formträger verbindbar ist, wobei insbesondere dem Reduziergetriebe ein Hilfsmotor zugeordnet ist,
• b) dass mit dem Antrieb ein Positionsgeber verbunden ist, über den der Antrieb zum Aufschrauben der Form am Formträger für eine vorbestimmte Winkelumdrehung einschaltbar ist, wobei bevorzugst eine Strahlungsquelle, insbesondere Lichtquelle, vorgesehen ist, die gegen einen Umfangteil des Formträgers z.B. im Bereich der Löcher oder einer Markierung, gerichtet ist, und über den reflektierten Strahl ein Sensor, z.B. Photozelle, beaufschlagbar ist, der den/die Motor(en) und gegebenenfalls die Bewegung eines Kupplungselementes steuert, welcher Sensor gegebenenfalls mit einem Schalter überbrückbar ist.

An automatic, program-controlled attachment of the mold to the mold carrier can be achieved according to the invention in that a servo-actuating device is provided for loosening and / or screwing the thread, and that preferably the press drive itself serves as a servo-actuating device and for a screwing movement of the threads of the mold or mold carrier with the aid of a switching device to at least two speeds which can be switched by at least one order of magnitude, preferably at least two, and / or has a turning device, expediently at least one of the following features being provided:

• a) that a drive motor for direct drive can optionally be connected via a clutch from its motor shaft or via a reduction gear to the mold carrier, in particular an auxiliary motor being assigned to the reduction gear,
• b) that a position sensor is connected to the drive, by means of which the drive for screwing the mold onto the mold carrier can be switched on for a predetermined angular rotation, preferably a radiation source, in particular a light source, is provided, which against a peripheral part of the mold carrier, for example in the region of the holes or a marking, and a sensor, for example a photocell, can be applied via the reflected beam, which controls the motor (s) and, if appropriate, the movement of a coupling element, which sensor can optionally be bridged with a switch.

• Fig 1 zeigt eine bekannte Pelletpresse im Axialschnitt mit einem Detail A, das in den
• Fig 2 bis 5 in verschiedenen erfindungsgemässen Ausführungsvarianten im grösseren Massstabe dargestellt ist;
• Fig 6 ist eine axonometrische Darstellung eines in den Ausführungen nach den Fig. 2 bis 5 verwendeten Verriegelungsbolzens, wobei
• Fig 7 die Anordnung solcher Verriegelungsbolzens relativ zur Form in einer teilweisen Stirnansicht auf dieselbe veranschaulicht ist;
• Fig 8 zeigt eine bevorzugte Ausführungsform in einer den Fig. 2 bis 5 ähnlichen vergrösserten Darstellung des Details A aus Fig. 1;
• Fig 9 zeigt die Pelletpresse in Draufsicht mit einer automatischen, programmgesteuerten Befestigung der Form am Formträger;
• Fig 10 bis 12 verschiedene Einrichtungen zur erleichterten Gewindeverdrehung;
• Fig. 13 eine Pelletpresse in Ansicht von vorne, wozu
• Fig. 14 einen Schnitt nach der Linie XIV-XIV der Fig. 13,
• Fig. 15 einen Schnitt nach den Linien XV-XV der Fig. 13, die
• Fig. 15A eine Variante zu Fig. 15,
• Fig. 16 einen Schnitt nach der Linie XVI-XVI der Fig. 13, und
• Fig. 16A eine Variante zu Fig. 16 veranschaulichen.

The invention is explained in more detail below with reference to the drawing:

• Fig. 1 shows a known pellet press in axial section with a detail A, which in the
• 2 to 5 are shown on a larger scale in different embodiment variants according to the invention;
• 6 is an axonometric view of a locking bolt used in the embodiments according to FIGS. 2 to 5, wherein
• Figure 7 illustrates the arrangement of such locking bolts relative to the mold in a partial end view thereof;
• 8 shows a preferred embodiment in an enlarged illustration of detail A from FIG. 1, similar to FIGS. 2 to 5;
• 9 shows the pellet press in a top view with an automatic, program-controlled attachment of the mold to the mold carrier;
• 10 to 12 different devices for facilitating thread rotation;
• Fig. 13 is a pellet press in front view, for what
• 14 is a section along the line XIV-XIV of FIG. 13,
• Fig. 15 is a section along the lines XV-XV of Fig. 13, the
• 15A shows a variant of FIG. 15,
• Fig. 16 is a section along the line XVI-XVI of Fig. 13, and
• 16A illustrate a variant of FIG. 16.

In a pellet press 1 (FIG. 1), material to be processed is fed via a hopper 2 to a metering device 3, which feeds a predetermined amount of this material to a mixer 4, to which steam is simultaneously fed via a steam line 5 (FIG. 9). The material mixed in this way then enters a kinked channel 6, which feeds it to a mold cover 7, from where it enters the interior of a press mold 9 via scraper blades 8 and there with the aid of a press roll 9a is pressed through the radial bores 9b of this die.

The mold 9 is held in a conventional embodiment with the aid of a ring 11 fastened to a rotatable mold carrier 10 and a clamping ring 13 which can be pulled by bolts 12 in a conical seat of the ring 11. The mold carrier 10 is turned by hand to insert the levers into existing holes 14 to tighten the bolts 12, which holes are accessible via a side door 15a (FIG. 9). The normal drive of the parts 9 to 14, however, takes place via a drive wheel 15 which is driven by means of a V-belt from a drive motor 16 (FIG. 9) via a V-belt wheel 17. Instead of the V-belt drive shown here by way of example, any other type of drive could of course also be selected.

The invention is based on the object of simplifying and improving the arrangement in area A of FIG. 1.

2 serves primarily to avoid the work involved in screwing and to secure the centering of the compression mold 9 on the mold carrier 10 by means of centering jaws 34 and to clamp it with clamping jaws 34 '(right edge indicated by dashed lines). The jaws 34, 34 'are alternately distributed over the circumference.

For this purpose, a plurality of cup-like centering parts 18 are provided on the press mold 9, or instead of several such cups, a U-shaped rail 18 (see FIG. 7), as can be seen in FIG. 2, is e.g. attached to form 9 by welding. The mold carrier 10 has an annular recess 19 with an insert part 20 which has a similar recess 21, the rail 18 being insertable into the recess 21.

As shown in FIG. 7, the rail 18 has elongated holes 22 aligned in the circumferential direction, some of which are distributed over the circumference of the rail 18. The elongated holes 22 are designed such that an elongated head 23 of a bolt 24 can enter these elongated holes 22. This bolt 24 is shown in section in FIG. 7. Its exact design can be seen in FIG. 6.

The bolt 24 has an approximately helical groove 25 with such a pitch that this "thread" is in any case not self-locking. At each end of the helical groove 25, which extends over about a quarter of the circumference of the bolt 24, there is an end part 26 which runs parallel to the axis. The bolt 24 is or the like by disc springs. 27 (based on Fig. 2) against the right side. A groove attached to the mold carrier 10, e.g. a protrusion or pin 28 penetrating a bearing sleeve 28 '. A displacement of the bolt 24 in the axial direction must therefore inevitably involve a rotation of the bolt by 90.

A piston-cylinder unit 29, 30 is arranged behind the bolt 24, the piston 30 of which carries a stamp 31 at its left end. If pressure medium is now applied to the piston 30 via a line 32, this overcomes the force of the springs 27 and pushes the pin 24 to the left. The bolt 24 is rotated by 90 due to the threaded groove 25 so that its elongated head 23 is aligned with the elongated hole 22 (FIG. 7). In this position, the mold 9 can be pulled off the bolts 24 or a new mold can be put on. As soon as a new press mold is attached, the piston 30 is relieved, whereupon the bolt 24 moves to the right under the load on the plate springs 27 (with reference to FIG. 2) and thereby reaches the locking position shown in FIG. 7 due to the threaded groove 25. The U-shaped rail 18 is pulled into the recess 21 and a central fit of the mold 9 is ensured. Then the mold only needs to be fastened in this central position, for which purpose the recess 21 has an inclined surface 33 on its outside, into which the clamping jaws 34 'can be retracted with the aid of screw bolts 35.

In the embodiment according to FIG. 3, the screw bolts 35 can be omitted if a recess 121 with an inclined surface 133 lying on a somewhat smaller diameter is provided, which cooperates with a corresponding inclined surface 36 of the compression mold 9. In this case, the springs 27 must be designed such that the mold 9 is frictionally clamped on the inclined surface 133, a positive connection being obtained via the bolts 24 and the U-rail 18.

4 and 5 show an embodiment variant in which, instead of the bolts 35 in FIG. 2, there is a clamp fastening with the aid of a pressure medium, the compression mold 9 being drawn into the mold carrier 10 in the same manner as in FIG. 2 and 3.

In the case of FIG. 4, at least one printing unit 37, but possibly also a number thereof, is provided on the back of the mold carrier 10 or (in the case of several) distributed over its circumference. Each of the pressure units 37 has a piston 38, the piston rod 39 of which protrudes outwards at the rear and can be actuated in an arbitrary manner, not shown, via an annular plate 40 connected to these piston rods 39. For example, the ring plate 40 could be screwed to the left (based on FIG. 4) or be moved to the right. Alternatively, the piston rod 39 could also be replaced by a screw and actuated, for example, in the manner described later with reference to FIG. 16A.

A, preferably hydraulic, pressure medium is accommodated in a line system 41 on the left side of the piston 38. This line system 41 opens out on the side of the mold 9 into a space 42 which is separated by a e.g. made of sheet metal, membrane 43 is completed. Therefore, if the piston 38 is moved to the left with reference to FIG. 4, the diaphragm 43 expands and presses against the U-shaped rail 18 on the one hand and against an annular shoulder 44 of the press mold 9 on the other hand. The press mold expediently has a corresponding one Indentation (not shown) into which the membrane (or a piston) can penetrate.

While a certain mechanical work for adjusting the ring plate 40 is still necessary in the embodiment according to FIG. 4, this work can be further simplified by the embodiment according to FIG. 5. Here, instead of the hydraulic pressure units 37 (FIG. 4), similar units 137 are provided, which, however, have the function of a pressure accumulator or buffer. A line 45 can be supplied from a pressure medium supply 46 with the aid of a pump 47, which pumps the pump via a check valve 48 into the unit 137 and the line system 41. If, on the other hand, the membrane 43 is to be relieved, only one valve 49 in a branch line 50 needs to be opened, whereupon the pressure medium flows back into the reservoir 46. The piston 138 of the unit 137 is expediently loaded by a spring 51 (it can also be a gas spring) which compensates for any pressure peaks that may occur. For monitoring purposes, pressure sensors can be connected which, for example, trigger an alarm when the value falls below a target value.

It goes without saying that the bolt 24, which acts as a locking element which can be actuated in the axial direction, can be modified in various ways. For example, he himself can carry the pin 28, while the groove 25, 26 is incorporated in the bearing sleeve 28 '(which carries the pin 28 in the illustration of FIGS. 2 and 3). 6, it will also be easy to imagine that the bolt 24 is formed in two parts, the front part 23a of reduced diameter being the piston rod of a piston which can be displaced in a cylinder 24 and acted upon fluidically. In this case, the piston rod 23a can carry a guide projection corresponding to the pin 28 and can be rotated by a groove 25, 26 formed in the cylinder 24, so that no further unit 29, 30 is then required.

It also goes without saying that it can be advantageous to provide springs 51 or a gas cushion (as is customary in pressure accumulators) in the pressure unit 37 according to FIG. 4. The connection for the line system 45 to 50 on the pressure unit 37 or 137 may have an additional valve (not shown) in order to be able to close off the respective unit after supplying it with pressure medium, but the valves 48, 49 can also be directly on the pressure unit unit 37 and 137, respectively, so that there is a coupling connection for lines 45 and 50. In this case, the check valve 48 could be provided on the pressure unit 137 and this a coupling for the optional connection of, e.g. branched connection of e.g. have branched pressure line in which the valve 49 and (e.g. in a parallel branch) the pump 47 are provided.

In the preferred embodiment shown in FIG. 8, the mold 9, similar to the embodiment according to FIG. 3, has an inclined surface 36. As in the case of FIG. 3, this inclined surface 36 on the side of the mold carrier 10 is opposite an inclined surface 133 on an insert part 120. It goes without saying that the mold carrier 10 itself could have the inclined surface 133 instead of an insert part 120, but the use of an insert part 120 is preferable because it is easier to replace in the event of wear and tear. In any case, the insert 120 is screwed onto the mold carrier 10 with the aid of screw bolts 135. It should be noted here that these bolts 135 do not normally need to be loosened when the shape is changed.

The insert part 120 is also characterized in that it is equipped with a, preferably multi-start, thread 52. Likewise, the mold 9 carries a threaded ring 54 which is screwed onto it with the aid of screws 53. For this purpose, the mold 9 is equipped with corresponding screw holes 55 on both end faces.

When changing the shape, the press mold only needs to be screwed into the thread 52 with its threaded ring 54, the inclined surfaces 36, 133 ensuring a tight fit. Incidentally, it is also understood here that the threaded ring 54 could possibly itself be part of the compression mold 9.

The two threads 52, 54 are designed to be self-locking. It should also be mentioned that the screw holes 55 are arranged approximately in the middle of the thickness of the die 9, since the stresses are lowest there during operation. In addition, the symmetrical design with screw holes 55 on both ends of the mold 9 also has the advantage that the mold carrier 10 is removed turned threaded holes, a reinforcement ring, which is usually attached to the front, can be screwed into the same screw holes 55.

Since the thread is expediently designed such that it is rotated in the normal direction of rotation of the mold carrier 10 in the sense of being screwed in, it may tighten too much during operation, so that the loosening of this threaded connection can be difficult. Various designs for facilitating rotary fastening via threads or for loosening them with the aid of servo-actuating devices will now be discussed with reference to FIGS. 9 to 16A, i.e. So devices that allow twisting of the threaded parts to be achieved with minimal effort, even if they are seized.

With reference to FIG. 9, it is shown how the drive for the pellet press 1, which is available per se, can be used in the case of a threaded connection between the mold 9 and the mold carrier 10. For this purpose, the V-belt wheel 17 already mentioned has two conical coupling recesses 56, 57 in its interior, each of which has a coupling cone 58 or 59 opposite it. While the cone 58 is axially displaceable and rotatably connected to the motor shaft 60 of the drive motor 16, the cone 59 sits on an output shaft 61 of a reduction gear 62, which receives its drive from an auxiliary motor 63. The cone 59 is also connected to the output shaft 61 in a rotationally locking but axially displaceable manner. Both cones 58, 59 are adjustable by a common actuating device 64, so that only one of the two cones 58, 59 can be coupled to the V-belt wheel 17. For example, two moving coil magnets 65, 66 can serve as the adjustment drive.

With the help of the reduction gear 62, a strong reduction of at least one order of magnitude, preferably at least two, can be achieved, the speed ratio being approximately 1: 200, for example. It would be conceivable to achieve such a speed difference with purely electrical means, for example by using additional windings, by a DC motor with appropriate control for at least two speeds or the like. However, it is understood that the interposition of a reduction gear 62 is the structurally simpler way. It would be possible per se to design the reduction gear 62 in such a way that it can optionally be driven by the drive motor motor 16, so that the auxiliary motor 63 is saved. However, this would require greater gear expenditure than could be saved, which is why the auxiliary motor 63 is preferred.

It should be mentioned that the problem of providing a main drive and an additional slow drive (and this is what it is here) also exists in cinema projectors, namely, either at a normal speed or (for a search or single image switching) a slow speed to achieve. Here, too, reduction gears are used, but driven by the (single) main motor, and these known solutions can also be used for the present purposes. Similar to how, for example, the wing panel of the projector is driven on a circumference via the reduction gear, a circumference of the mold carrier could also have a drive surface, e.g. have a ring gear for the engagement of a reduction gear.

The thread 52, 54 (FIG. 8) is now preferably designed such that a rotation between 15 "and 100" is sufficient to tighten the mold 9 on its mold carrier 10. Therefore, if the auxiliary motor 63 is switched on in order to rotate the mold carrier 10 at reduced speed, it is advantageous if an automatic shutdown takes place as soon as the mold 9 is fastened to the mold carrier 10. In the circuit according to FIG. 9, this is solved in different ways.

One possibility is to provide a light source 67 for illuminating the outer circumference of the mold carrier 10. The arrangement is such that the light beam strikes the area in which the holes 14 are provided, which then simultaneously serve as markings. It goes without saying that any other marking can of course also be provided. If the light beam now falls on the outer circumference of the mold carrier 10, it is reflected against a photocell 68. On the other hand, if there is a hole 14, there will be no reflection. This means that the output signal of the photocell 68 is interrupted at each hole 14.

On the pellet press 1, a pulley 69 is pivotally mounted about an axis 70 and, for mounting the press mold 9, supports the same on a hook 71 at the correct height. If the mold carrier 10 is now set such that the light beam from the light source 67 is directed straight toward a hole 14, the auxiliary motor 63 cannot be excited even when a selector switch 72 is moved from the position shown in broken lines to the position shown in full lines is set. This selector switch 72 is in the circuit of a pulse shaper stage 73 to which a feed stage 74 is connected. The auxiliary motor 63 is not only supplied with current via the feed stage 74, but the direction of rotation can also be selected with the aid of a switch 75. The line coming from the pulse shaping stage 73 forms the Control line for the feed stage 74. Of course, the reversing device 74 can also be designed purely mechanically, ie as a reversing gear.

If you now want to put the auxiliary motor 63 into operation, it is sufficient to briefly close a switch S1, as a result of which the photocell 68 is bridged until it again receives reflected light from the outer surface of the mold carrier 10. The time constant of the pulse shaper 73 is dimensioned accordingly. At the same time, the moving coil magnets 65, 66 are excited to such an extent that the coupling cone 59 enters the coupling recesses 57, whereas the coupling cone 58 disengages. An interrupter 76 may be provided so that the magnet 65 cannot be energized by mistake. This interrupter 76 is parallel to a control line for controlling a stage 174 similar to the feed stage 74 for the drive motor 16. As soon as the auxiliary motor 63 slowly drives the mold carrier 10, the threaded rings 52, 54 (see FIG. 8) are screwed together, whereby with the appearance of the next hole 14 on the outer circumference of the mold carrier 10, the current is interrupted via the output signal of the photocell 68.

The selector switch 72 can also be connected to a terminal 77, which is located at the output of a counter Z. In this case, the control is time-dependent, i.e. as soon as the counter Z has received a predetermined number of pulses from a pulse generator 78, a switch-off signal occurs via the pulse shaping stage 73.

Since it would be conceivable that the mold 9 is not set at the correct height or position with the aid of the pulley 69, a jamming of the thread would manifest itself in the occurrence of forces acting on the hook 71. It may therefore be expedient to mount a strain gauge 79 there, which then presses against the hook 71 due to the torque and emits an output signal which is inverted via an inverter 80; i.e. when an unusual voltage occurs on the strain gauge 79, the output signal of the inverter 80 is interrupted. Therefore, if the selector switch 72 is connected to a terminal 81, the operation of the auxiliary motor 63 is either interrupted if a positioning error occurs, or if the mold 9 is screwed tightly to the mold carrier 10, in which case the mold 9 is also located gives a torque.

It is now readily possible to use the strain gauge 79 for control purposes in order to detect incorrect positioning, but at the same time also to let the photocell 68 act. For this purpose, the selector switch 72 must be set to the terminal 82, which is decoupled from the terminal 81 via a valve circuit (diode D), so that the photocell at the terminal 81 is ineffective. Since the terminal 82 is controlled via a gate circuit 83, the auxiliary motor 63 can only run if the photocell 68 emits a signal and the strain gauge 79 remains fault-free.

A simplified circuit could also be designed such that the auxiliary motor 63 is only switched on and off manually by means of the pushbutton switch S1. In this case, the further parts 67 to 73 of the circuit shown in FIG. 9 are unnecessary.

However the circuit is designed, it is preferable to provide a corresponding device Z, 68 or 79 by which the end of the screwing process is indicated. It goes without saying that the direction of rotation of the auxiliary motor 63 is reversed by switching the lever 75, so that in this way the mold 9 can also be released from the mold carrier 10 with the aid of the motor force.

However, if simpler means are to be used, the explanations according to FIGS. 10 to 12 come into question. In the case of FIG. 10, an insert ring 220 is provided which supports the inclined surface 133, but a threaded ring 152 separate from this insert ring 220 is arranged. The threaded ring 152 has on its outside a toothed ring, into which a pinion 84 engages and can be driven by means of a socket wrench to release the threaded connection on the back of the mold carrier 10.

The solution according to FIG. 11 is similar, but the threaded ring 252 has on its outside a worm toothing in which a worm 85 engages approximately tangentially and has a connection for a socket wrench 10 on the outside of the mold carrier 10.

The embodiment according to FIG. 12 is even simpler, in which an external threaded ring 352 has a notch recess 86 on its radially outer side. A screw bolt 87, which is inserted approximately tangentially on the outer circumference of the mold carrier 10 and protrudes into this notch recess, the threaded ring 352 being rotated counterclockwise when it rotates within a recess 88. In this way, an excessively tight thread can be easily loosened.

It can therefore be seen that it is advantageous to provide at least one actuation or drive device for the screw connection, this drive device being arranged at least in the sense of loosening the screw connection.

FIG. 13 shows a pellet press in a view from the front, wherein the mold carrier 10 has threaded segments 89 located at an angular distance from one another. The mold 9, however, preferably has an uninterrupted Ge windering, although the reverse arrangement (mold with thread segments and mold carrier with full thread) or an arrangement in which the mold also has 9 thread segments would also be conceivable, so that the mold does not have to be screwed into the mold carrier, but rather only inserted with offset thread segments and then rotated approximately by the radian measure of the thread segments. Such closures are known, for example, from artillery and have proven themselves there in view of their particularly high robustness and durability. In any case, temperature and vibration loads also occur with artillery breeches.

According to FIG. 14, the compression mold 9 has a threaded ring 54 which is expediently connected to the same via screws 53, although it could also be designed in one piece. The mold carrier 10 has, for example, a ring 90 which is provided with the threaded segments 89 inserted in the recesses. If necessary, however, the ring 90 can also be formed in several parts, both in the circumferential direction - with non-threaded sections 90b being provided between the threaded segments 89 - and in the axial direction, with an outer part 90a having a conical mating surface which matches the conical mating surface of the press mold 9 cooperates. Therefore, the sections 90b can be fastened with separate screws 98 (FIG. 14), the thread segments 89 (FIG. 15) with screws 91, as will be explained below.

If, as in the case of FIG. 13, four different thread segments 89 are offset over the circumference of the mold carrier 10, it is expedient if the associated thread is a four-start thread, since then, with a corresponding pitch, it can easily be set up so that one Thread of the threaded ring 54 can engage in the thread of the threaded segments 89 without these having to be axially offset. This saves on length in the axial direction. If a different number of thread segments 89 is selected, it is again favorable to adjust the number of thread turns to the number of thread segments.

15 shows the section through a section of the multi-part threaded ring 90 with a threaded segment 89, the threaded segment 89 being held in place by means of screw bolts 91, a sleeve 91 a and plate springs 93. The plate springs permit an elastic displacement of the threaded segment 89 parallel to the axis of the mold carrier 10 if they are either fluidically loaded by means of a cylinder-piston unit 95 (FIG. 16) with the aid of a pusher 94 or by means of a rotary spindle 96 which will be described in detail later (Fig. 16A). Such an axial movement relieves the right flanks of the thread on the threaded segments 89, which seize themselves on the opposite flanks of the threaded ring 54 due to the temperature influences and vibrations occurring during operation and due to the rotation of the mold carrier 10 expediently in the screwing direction can. However, if these flanks are now lifted from each other, unscrewing the mold is made easier again, the mold being simultaneously released from its conical seat.

The plate springs 93 do not necessarily have to be arranged on the outside of the mold carrier 10, as shown in FIG. 15, but can also be arranged in the mold carrier 10 according to FIG. 15a and provide a direct cushioning of the threaded segment 89, but act in the case 15 shows the springs 93 in the sense of positioning against the cylinder-piston unit 95, in the case of FIG. 15A in the sense of loosening.

The cylinder-piston unit 95 shown in FIG. 16 and arranged between two plate spring assemblies 93 according to FIG. 13 is expediently of a similar design, as illustrated in FIG. 5. Above all, it will expediently not be constantly connected to a pressure source, but will only be connected to such a pressure source when the mold carrier 10 is at a standstill to release the mold 9.

In the embodiment according to FIG. 16 a, the threaded segment 89 is moved via pushers 94 in a manner similar to that according to FIG. 16. In principle, a single rotary spindle 56 shown or a cylinder-piston unit 95 can suffice. However, if a plurality of rotating spindles 96 are distributed over the circumference of the mold carrier 10, these can be actuated jointly by a chain 97 and chain wheels 99. Analogously, a plurality of cylinder-piston units 95 can also be connected to one another via fluid lines.

It must be pointed out in connection with the various constructive solutions that, in the mechanically operated embodiments, the dimensional changes due to heat can cause different movements. However, hydraulic pressure elements with storage springs 51 (FIG. 5) are able to compensate for these dimensional changes, the type of suspension (e.g. also gas spring) being irrelevant.

It goes without saying that the axially elastic fastening of the thread or the thread segments 89 to the mold carrier 10 can also be realized without the devices 95 or 96, in which case the pusher 94 can be made by hand, for example by means of a corresponding one Tool to be operated (see FIG. 15A). In principle, an analogous effect could of course be achieved by an elastic fastening of the threaded ring 54 to the compression mold 9, but the elastic displacement in the axial direction will usually be more difficult to achieve there, which is why the elastic fastening of the thread on the support side is preferred on its own.

Within the scope of the invention, it is readily possible to exchange individual or more of the features described with one another, to use them in other combinations with one another or with features of the prior art, or even on their own; the latter applies not only to the features a) to c) mentioned in claim 1, but also to the described embodiments of the slow drive of the pellet press, which are also of importance independently of the other features, as well as the use of pressure sensors 79 for Check the fit of the mold on the mold carrier. Such sensors could also be used, for example, in the case of the embodiments according to FIGS. 10 and 11.

Claims (10)

1. Pellet press with a hollow cylindrical mould (9) which has substantially radial bores (9b) and on whose internal peripheral surface at least one press roller (9a) is arranged which is situated eccentrically thereto, said roller being adapted to roll on said surface, and the mould has or carries at an axial end region an external rotation surface (36; 44) which is insertable in a corresponding internal rotation surface (33, 34) of a rotatably mounted mould carrier, concentrically with respect to the latter, and which is releasably secured by means of a holding device, said mould carrier being connected in force-locking manner to a drive, characterised in that the holding device (18-26; 43, 44; 52, 54) is divided into two, whereof one part (18-22; 44; 54) is provided at the mould (9) and the other part (23-26; 43; 52) at the mould carrier (10), which latter part is bringable from a position of rest wherein insertion of the mould (9) axially into the internal rotation surface (21, 33) of the mould carrier (10) is made possible, into a working position wherein the two parts are in force-transmitting engagement with one another, and the mould is bringable, by means of a device (27; 29-32; 52) producing said force, into a clamping position wherein the mould (9) is centred by means of a centring device (33, 34; 133, 30; 44, 121) in the mould carrier (10), and the two parts are releasable from one another again by means of a releasing device (29-32; 84, 152; 85, 252; 86-88; 94-96), advantageously from a positive-locking engagement,

and that the holding device has preferably at least one of the following feature groups,

a) there is provided indirectly or directly in the mould carrier (10) at the internal rotation surface at least one substantially radially fluid-actuatable fixing element e.g. a diaphragm (43) which is applicable against the external rotation surface (44) of the mould (9);

b) that the mould (9) is provided at at least one of its end faces with at least one undercut aperture (22), and that a fixing element (23a) engaging in the aperture (22) and with a gripping surface (23) projecting at an angle relatively to its longitudinal axis, is rotatable by means of an especially fluid-operated actuating device (25-32) through a predetermined angle, at which the gripping surface (23) grips the undercut of the aperture (22);

c) that concentric inter-engaging especially self-locking screwthreads (52) are provided indirectly or directly on the mould carrier (10) and the mould (9).

2. Pellet press according to claim 1, characterised in that the axially and/or radially fluid-actuatable fixing elements (23a, 24, 43) are constructed to act distributed about the periphery of the mould.

3. Pellet press according to claim 1 or 2, characterised in that at least one pressure accumulator (137) is provided in the fluid conduit for the fixing elements.

4. Pellet press according to claim 1, 2 or 3, characterised in that there is associated with the holding device at least one fluidic actuating device with a piston and cylinder unit (29, 30), by means of which device there is actuatable a ram (23a; 31) separate therefrom and with a piston (30) situated in a hydraulic cylinder (29), and/or

that the fixing element (23a, 24; 43) which is fluid-actuatable in one direction is acted upon in the other direction by at least one especially mechanical spring device e.g. by cup springs (27), preferably in the direction towards the holding position.

5. Pellet press according to one of claims 1 to 4, characterised in that the external rotation surface (36) of the mould (9) is constructed as a cone, which is introduceable into a matching cone (33) of the mould carrier (10), which cone forms the internal rotation surface (33; 133) and is situated therein as a separate ring if appropriate.

6. Pellet press according to one of claims 1 to 5, characterised in that the respective radially actuatable fixing element is constructed as a diaphragm (43) pressable against the external rotation surface (44) of the mould (9).

7. Pellet press according to one of claims 1 to 6, characterised in that at least one fixing element (23, 24), rotatable to the extent of a predetermined angle, has especially all of, and at least one of, the following features;

a) a substantially rectangular head (23) projecting to both sides from the shank,

b) an actuating device associated with it, for axial movement, the rotational movement of said head being effected by means of a rotation guide device (25, 28),

the rotation guide device preferably having a projection, especially a stud (28), e.g. on the piston (23a), adapted to be guided in a helical groove (25) e.g. in a guide cylinder (24), and conveniently the groove (25) has detent positions at its two ends, especially end portions (26) extending parallel to the axial direction.

8. Pellet press according to one of claims 1 to 7, characterised in that a plurality of undercut apertures (22) are distributed over the end face of the mould (9), these being especially formed on an encircling strip (18) fixed to the mould (9), which strip is insertable into an appropriate recess (21) of the carrier.

9. Pellet press according to one of claims 1 to 8, characterised in that at least one of the following features is provided for the screwthread (52) at the mould carrier (10) and mould (9) :

a) the fixing position is attainable on relative rotational movement of the screwthreaded parts through 15 to 100°,

b) the screwthread is conical,

c) the screwthread is a multi-thread screwthread,

d) on the mould (9) and/or the mould carrier (10), preferably on the latter, there are arranged peripherywise spaced-apart screwthreaded segments (89), and preferably the number of screwthreaded segments (89) is equal to the number of threads of the multi-thread screwthread,

e) the screwthread of the mould (9) and/or of the mould carrier (10), preferably of the latter, is secured to be elastic in the axial direction, especially by means of cup springs (93),

f) it is arranged on at least one screwthreaded ring (54) which is connected releasably, especially by means of screws (53, 135), to the mould (9) or the mould carrier (10), preferably to the former,

g) the working rotational movement direction of the mould carrier (10) is chosen to be in the direction of a screwing-in of the screwthreads,

h) the mould (9) is connectable to a lifting device e.g. pulley block which has a pressure-measuring e.g. strain gauge device by means of which a screwthread servomotor (63) for relative rotational movement of the screwthreaded parts is controllable,

i) the internal screwthread of the mould carrier (10) is constructed on a screwthreaded ring (152; 252) and is provided externally at least partly with a tooth system by means of which the screwthreaded ring (152) mounted in the mould carrier (10) to be at least partly rotatable is adapted to be driven in rotational movement (Figs. 10, 11), advantageously the teeth of the screwthreaded ring (152) having a toothed pinion (84) or a worm (85) engaging in them.

k) the mould carrier (10) internal screwthread, arranged on an at least partly rotatably mounted screwthreaded ring (352), has at least one peripheral recess (88) which extends parallel to a tangent to the screwthreaded ring and against which a pressure element, especially a screw bolt (87), is adapted to bear (Fig. 12),

I) the internal screwthread of the mould carrier (10), formed on a screwthreaded ring (90), is mounted to be possibly partially rotatable, with axial play, in the mould carrier (10), and advantageously either the screwthreaded ring (90) is held by means of screw bolts (91, 92) preferably elastically, especially with the use of cup springs (93), on the mould carrier (10), and/or the screwthreaded ring (90) is adapted to be acted upon by means of at least one pressure element (94) actuatable in the axial direction e.g. by means of at least one piston and cylinder unit (95) or by means of at least one rotary spindle (96), and especially a plurality of pressure elements (94) are distributed over the periphery and are actuatable possibly jointly e.g. by means of a chain (97).

10. Pellet press according to one of claims 1 to 9, characterised in that a servo actuating device (62, 63; 84; 85; 87) is provided for releasing and/or screwing-on the screwthread (52, 54; 152; 252, 89),

and that preferably the press drive (16, 63) itself serves as the servo actuating device (62, 63; 84; 85; 87), and for a screwing movement of the screwthreads of mould (9) and mould carrier (10) is adapted to be changed-over with the use of a switch-over device (56-66) to at least two speeds differing by at least one order of magnitude, preferably at least two such, and/or

comprises a rotation direction reversing device (74),

and advantageously one of the following features is provided:

a) that by means of a clutch (56, 57) a drive motor (16) is selectively connectable for direct drive from its motor shaft or via a reduction gear (62) to the mould carrier (10), and especially an auxiliary motor (63) is associated with the reduction gear (62),

b) that there is connected to the drive (63) a position transmitter system (14, 67, 68) by means of which the drive (63) is adapted to be switched on for a predetermined angle of rotation for screwing the mould (9) on the mould carrier (10),
there being provided preferably a radiation source, especially a light source, which is directed towards a peripheral portion of the mould carrier (10), e.g. in the region of the holes (14) or a marking, and by means of the reflected beam a sensor (68) e.g. a photoelectric cell can be acted upon which controls the motor/motors and possibly the movement of a clutch element (56, 57), which sensor (68) can be bypassed with a switch (S1) if appropriate.

Images