Mould closing unit with heat management

A mould closing unit (100) for an injection-moulding machine has an electromechanical closing mechanism (M) for opening and closing an injection mould, said electromechanical closing mechanism (M) being actuated by means of at least one spindle unit (10) having at least one spindle (12) and at least one spindle nut (14). Cooling by way of cooling ducts (32) for heat dissipation from the spindle unit (10) is provided. Since the spindle (12) has, in the core, at least one bore (24) in which a cooling and/or lubricating medium is passed into the region of the contact points between the spindle nut (14) and the spindle (12) via at least one lance (20), efficient cooling of the spindle unit is achieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application refers to and claims the priority of the German patent application 10 2016 119 581.2, filed on 13 Oct. 2016, the disclosure of which is hereby expressly incorporated by reference into the subject matter of the present application in its entirety.

FIELD OF THE INVENTION

The invention relates to a mould closing unit for injection moulds on an injection moulding machine for processing plastics materials and other plasticizable masses such as ceramic or powdery masses, according to the preamble of claim1.

PRIOR ART

Injection moulding machines and mould closing units for injection moulding machines with cooling concepts for heat or power dissipation are known in different forms. The necessity of a cooling concept arises from the large efficiency losses which are introduced into the system by means of a friction increase due to the thermal expansion of the individual elements, in order to protect the elements against increased wear and thermal overload.

From DE 10 2008 051 285 B3, there is known a mould closing unit with a direct cooling of the bearing position of the spindle drive and/or a cooling plate associated with one of the bearing positions. Cooling channels pass through the bearing position and/or the cooling plate associated with the bearing position, so that by means of the direct cooling, an increased working life of the spindle system and an increased working life of the bearing result.

From EP 0 658 136 B1 a mould closing unit is known in which a liquid-cooled servomotor is used as a symmetrical drive and force-transmission system. The servomotor drives a lead screw which is connected rotationally fixed to a crosshead engaging with the toggle joint system or systems. By this means, there results a minimum size and it is possible also to apply very large torques even during a stoppage. The heat energy conducted away by the water as a cooling medium from the electric servomotor can be recovered and subsequently used, for example, for mould temperature control.

In DE 10 2010 051 766 A1, a spindle drive for an injection moulding machine is disclosed which comprises a lubrication region between the spindle and the spindle nut and a sealing region. Situated at one end of the lubrication region is a first lubrication oil seal which delimits the lubrication region and abuts the spindle. Situated at the same end of the lubrication region at the side of the first lubrication oil seal facing away from the lubrication region is a second lubrication oil seal abutting the spindle. By means of the first seal, lubrication oil is held in the lubrication region. If, nevertheless, lubrication oil penetrates into the sealing region, the lubrication oil is wiped off by the second seal, so that the lubrication oil can flow away through an outlet opening arranged between the two seals. The aim is a targeted lubrication and lubricant removal at a drive spindle, whereby thermal considerations play no part.

A preform for the manufacturing of containers, in particular PET bottles, by means of stretch blow moulding is disclosed in DE 10 2012 108 061 A1. The mould cavity consists of a cavity, a core, a collar ring, a support ring and a bottom insert. The bottom part has a substantially conical portion and a gate point arranged on the hollow cylinder axis, whereby a connecting portion with a curved outer wall is provided between the conical portion and the gate point. For the most rapid possible cooling of the moulding material within the core, a feed channel is provided through which cooling water can be fed into the core. What is concerned here is thus the cooling of a die cavity, but not the cooling of mechanically cooperating components.

Nevertheless, with these solutions according to the prior art, due to the heat generation, thermal expansion of the individual components of the spindle unit also still occurs, which as a consequence, again leads to a greater power loss, caused by the increased friction in the interior of the spindle unit.

OBJECT OF THE INVENTION

Proceeding from this prior art, it is an object of the present invention to achieve a more efficient cooling of the spindle unit.

This object is achieved with a mould closing unit according to the features of claim1. Advantageous developments are the subject matter of the dependent claims. The features set forth individually in the claims are combinable in a technically useful manner and can be enhanced by means of explanatory circumstances in the description and details from the drawings, whereby further embodiments of the invention are revealed.

DISCLOSURE OF THE INVENTION

The mould closing unit comprises at least one first, preferably stationary mould carrier and a mould carrier that is movable relative to the first mould carrier, which together define a mould clamping chamber. A support element is also provided for an electromechanical closing mechanism which is actuated by means of at least one spindle unit and engages with the movable mould carrier, so that said mould carrier is cyclically moved and can be driven into an opening position and a closing position in relation to an injection mould. The spindle unit comprises at least one spindle, at least one spindle nut cooperating with the spindle and mounted in a bearing unit, and at least one motor mounted in a bearing element. For cooling, cooling elements pass through at least the bearing unit and/or the bearing element. According to the invention, the spindle has at least one bore in the core in which a coolant and/or lubricant is fed via at least one lance into the region of the points of contact between the spindle nut and the spindle, whereby the heat quantity arising can be conducted away and an efficient cooling of the spindle unit results. In principle, the invention can be transferred, not only to injection moulding machines, but also to other machines which have at least one spindle unit.

The bearing element encloses, with the support element, a bearing chamber in which the bearing unit is arranged and which is filled with the coolant and/or lubricant. Preferably, the bearing chamber is a closed bearing chamber in which cooling elements are provided, preferably in the form of a cooling coil for cooling the lubricant. As a result, a separation takes place between the transmission medium as cooling medium and the lubricant. Due to the volume of the bearing chamber, it is possible that advantageously sufficient coolant and/or lubricant is present for cooling and/or temperature control in the cooling path. A further advantage lies therein that the bearing unit is simultaneously lubricated, cooled and/or temperature-controlled.

The cooling system of at least two of the elements including the spindle unit, the spindle, the spindle nut, the bearing unit, the bearing elements and the motor is advantageously configured as a cooling path in parallel or series connection, e.g. with the requirement of feeding the coolest coolant and/or lubricant to the element with the greatest power loss. In this way, there results a need-based heat management with regard to a targeted cooling and/or temperature control. Also conceivable, however, are parallel connections of different cooling paths and/or of individual cooling channels of the individual elements of the spindle unit or combinations of series and parallel connections, so that an individual cooling concept adapted to the respective requirements can be created. Single path cooling systems and combinations thereof with parallel connections are also conceivable. It is also possible to configure the cooling paths freely, e.g. from outside inwardly so that, for example, the coolest coolant and/or lubricant is not fed to the element with the greatest power loss. However, any freely desired other arrangement of the elements in the cooling path is also conceivable.

Preferably, the cooling path is configured as a series connection of the elements from within the spindle unit outwardly. For example, the cooling path begins at the spindle and extends via the spindle nut and via the cooling coil into the motor. It is also conceivable, however, to guide coolant in a series connection from the spindle via the motor to the spindle nut, i.e. in the order of the greatest heat generation. In both cases, due to a cascaded construction, an optimum cooling concept results, even with relatively large machines in which, firstly, the heat arises to a greater extent and, secondly however due to the changed, larger dimensions particularly in the interior of a spindle drive, the heat is more difficult to conduct away.

In order to ensure effective cooling for the spindle, the cooling path is preferably configured as a series connection, wherein advantageously, the spindle is the first part of the cooling path. By means of the cooling, it is prevented that the spindle expands thermally and that damage thus arises. Also conceivable, in principle however, is the cooling of the spindle at any other position within the cooling path. It is also conceivable that the cooling path is configured as a parallel connection or as a combination of series and parallel connection.

Advantageously, the coolant and/or lubricant comprises oil. Also conceivable, however, is any other medium that is capable of absorbing and giving up heat, for example, water, and/or that is suitable for lubricating.

For an adequate heat management of the individual elements, advantageously, the spindle and the bearing unit are spatially separated, which leads to a thermal decoupling and thus enables independent cooling and/or temperature control of the individual elements.

For an advantageous additional protective safeguarding of the cooling path, the motor has an integrated thermal overload protection.

In order to absorb large axial loads and for an optimal circulation of the coolant and/or lubricant by virtue of the conveying effect, the bearing unit is advantageously configured as an axial spherical roller bearing. The result therefrom is no dead spaces in which the coolant and/or lubricant can dwell for long periods and thereby block the cooling path. In principle, however, other bearing units, such as for example, ball bearings are also usable.

Preferably, the bearing unit is likewise configured as a conveying means at least assisting the conveying of the coolant and/or lubricant.

For extremely high accuracy, apart from the normal cooling, advantageously, the spindle unit can be specifically temperature-controlled by means of the coolant and/or lubricant.

Particularly advantageously for a high degree of precision and good force transmitting properties with a relatively high packing density, the spindle unit is configured as a planetary roller screw drive. Also conceivable, however, are other force-transmitting units, for example, a ball screw drive or screw drives of all types.

For simple assembly, the bearing element is advantageously configured as a separate element and is not integrated into the support element. Due to the local decoupling of the bearing element and the support element, advantageously no additional transverse forces act upon the bearing element due to the deformation of the support element.

In addition to the gravity compensation in relation to a good retention of the spindle, the support element preferably also has additional radial support elements.

It is advantageous if the spindle nut and/or the bearing chamber has at least one cooling coil for conducting away heat energy arising. The cooling coil is preferably configured as a liquid cooler in a 2-circuit system. Also conceivable, however, is any other embodiment of the cooling coil and its arrangement, for example, as an external cooling arrangement or air/liquid cooling concept.

A bearing chamber cooled by lubricant and/or coolant is advantageously provided in which there is accommodated a lubricant for the cooperating parts of the spindle unit. Thus there is enabled a heat management system with two different cooling circuits which likewise enables a good cooling as well as a good cooling of the spindle unit.

If, in addition, the lubricant is advantageously arranged to be circulated by a movement of the bearing unit resulting from the cooperation of the parts of the spindle unit, a homogeneous distribution of the lubricant in the bearing chamber and thus a heat distribution in this region between the spindle nut and the spindle can be achieved.

Further advantages are disclosed in the subclaims and the following description of a preferred exemplary embodiment. The features set forth individually in the claims are combinable in a technically useful manner and can be supplemented by means of explanatory matters in the description and details from the drawings, wherein further modifications of the invention are illustrated.

DETAILED DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS

The invention will now be described in greater detail, by way of example, making reference to the accompanying drawings. The exemplary embodiments merely represent examples, however, which are not intended to restrict the inventive concept to a particular arrangement. Before the invention is described in detail, it should be noted that the invention is not restricted to the various components of the device and the various method steps, since these components and method can vary. The expressions used here are intended merely to describe particular embodiments and are not used restrictively. Furthermore, where the singular or the indefinite article is used in the description or the claims, this also relates to a plurality of these elements, provided the overall context does not clearly reveal otherwise.

FIG. 1shows a perspective view from obliquely above of a mould closing unit100for injection moulds on an injection moulding machine for processing plastics and other plasticizable masses such as ceramic or powdery masses with a first, preferably stationary mould carrier50, a second movable mould carrier52, which defines, with the stationary mould carrier50, a mould clamping chamber R, and a closing mechanism M which engages with a support element54by means of a crosshead58on the movable mould carrier52. Typically, a plasticizer unit (not shown in the drawing) is associated with the mould closing unit inFIG. 1from the left side.

For a cyclical opening and closing of the injection mould, an electromechanical closing mechanism M is provided on the support element54and is configured in the exemplary embodiment as a toggle joint mechanism. Other drives, for example, spindle drives or hydraulic drives are also conceivable as is another support for the closing mechanism M, for example, in a two-plate system in which one of the mould carriers50,52likewise forms the support element provided that an electromechanical closing mechanism is used. Through the actuation of the closing mechanism, the movable mould carrier52moves toward the stationary mould carrier50and away from it. The support element54, the crosshead58, the movable mould carrier52and the stationary mould carrier50are connected to one another via rods56. These rods56can—but do not have to—serve simultaneously as a guide for the movable mould carrier52. Alternatively, other force transmitting elements can also be provided which, for example, conduct the forces around the clamping chamber R. Preferably, the closing mechanism M is actuated by at least one spindle unit10, in the exemplary embodiment inFIG. 1, by two spindle units10.

FIG. 2shows the spindle unit10ofFIG. 1in perspective from obliquely above. It comprises at least one spindle12, at least one spindle nut14according toFIG. 3which cooperates with the spindle12and is mounted in a bearing unit30, and at least one motor18mounted on a bearing element16. A cooling system with cooling elements such as cooling channels32or also the bearing chamber26for conducting away heat from the spindle unit10passes through, in accordance withFIGS. 3 and 4, at least the bearing unit30and/or the bearing element16. Also conceivable in principle, however, are further cooling channels32through the spindle unit10, for example, through the motor18. In the exemplary embodiment, the spindle12has at least one bore24in the core, in which a coolant and/or lubricant is guided via at least one lance20into the region of the points of contact between the spindle nut14and the spindle12, whereby advantageously an efficient cooling of the spindle unit10results. Cooling connections22for flange-mounting and/or connecting the cooling path or the cooling channels32are situated, according toFIG. 2, at least on the lance20, the bearing element16and the motor18.

In a further preferred exemplary embodiment according toFIGS. 3 and 4, the bearing element16encloses, with the support element54, a bearing chamber26in which the bearing unit30is arranged and which is filled with the coolant and/or lubricant. Preferably, the bearing chamber26is a closed or encapsulated bearing chamber in which cooling elements are provided, preferably in the form of a cooling coil36for cooling the lubricant. As a result, a separation takes place between the transmission medium as cooling medium and the lubricant.

The support element54is configured in a preferred exemplary embodiment as a support plate or, in a two-plate system, can be, for example, one of the mould carriers50,52.

Preferably, the cooling of at least two elements including the spindle12, the spindle nut14, the bearing unit30, the bearing element16and the motor18is configured as a cooling path in series connection from inside the spindle unit10to the outside, with the proviso preferably of feeding the coolest coolant and/or lubricant to the element with the greatest power loss. For example, the cooling path begins at the spindle12and extends via the spindle nut14and via the cooling coil36into the motor18. Thus, the spindle12, the oil chamber and/or the bearing chamber26and the motor are cooled one after the other. For this purpose, inFIG. 2, cooling connections22of the spindle12are connected to the cooling connections22of the bearing element16and of the motor18in this order, so that the coolest coolant and/or lubricant reaches the spindle12first. The flow direction in the motor18is therein unimportant, so that a transfer of the coolant and/or lubricant directly from the bearing element16to the cooling connection22of the motor18is possible. Advantageously, projecting edges and hose lines are thereby minimized or eliminated. It is also possible to configure the cooling path freely, for example, from outside inwardly so that, for example, the coolest coolant and/or lubricant is not fed to the element with the greatest power loss. However, any desired other arrangement of the elements in the cooling path is also conceivable. Thus in a series connection, coolant can be fed from the spindle via the motor to the spindle nut, i.e. in the order of the heat generation.

Conceivable in principle, apart from a series connection, are parallel connections and/or a combination of series and parallel connection. Advantageously, with a parallel connection, individual and/or all of the cooling channels of the individual elements of the spindle unit10can be controlled individually and cooled and/or temperature-controlled independently of one another. A single-path cooling system or a combination of single-path cooling and parallel connection of the cooling channels32is conceivable. It is possible, for example, to cool the spindle12whilst the motor18is kept at a constant temperature.

In a particularly preferred exemplary embodiment, the cooling path is configured as a series connection, wherein the spindle12is the first part of the cooling path. Thereby, an effective cooling of the spindle12within the cooling path is ensured.

Oil is preferably used as the coolant and/or lubricant. Oil offers good properties with regard to the uptake and removal of heat energy and can advantageously be used simultaneously for lubricating elements of the spindle unit10, for example, the bearing unit30. However, other coolants and/or lubricants are also conceivable.

In order to realize an adequate heat management of the individual components of the spindle unit10, the spindle12and the bearing unit30are preferably spatially separated in accordance withFIGS. 3 and 4. Furthermore, the motor18drives the rotating element of the spindle12and the spindle nut14, in the exemplary embodiment the spindle nut14, via a drive shaft28. By means of the spatial separation, the elements are thermally decoupled and it is thus possible to cool or temperature-control the elements individually. In principle, however, the spatial separation of further elements of the spindle unit10, such as for example, the motor18is also conceivable.

Preferably, the motor18has an integrated thermal overload protection as a protective safeguarding of the cooling path. It is thereby advantageously achieved that in the case of too high a temperature of the cooling path, it can be cooled or temperature-controlled by means of cold coolant and/or lubricant. For example, on a further temperature increase, a switching-off takes place, which protects against thermal overload.

In the exemplary embodiment according toFIGS. 3 and 4, the bearing unit30is configured as an axial spherical roller bearing. By means of the conveying effect of the spherical roller bearing, an optimum circulation of the coolant and/or lubricant in the bearing chamber26is achieved. Preferably, a separation between coolant and lubricant takes place thereby. Whilst the lubricant is accommodated encapsulated in the bearing chamber26and is conveyed by the bearing unit30, it can be cooled by means of the coolant through the cooling coil36. Therefore, no dead spaces arise in which the coolant and/or lubricant can dwell for long periods and can thus block the cooling path. Thus, the axial spherical roller bearing can likewise be configured as a conveying means at least assisting the conveying of the coolant and/or lubricant. In principle, however, other bearing units30, such as for example, ball bearings which can also be configured as conveying means, are also conceivable. With the coolant and/or lubricant, it is preferably also possible to temperature-control the spindle unit10in a targeted manner.

The circulation of the coolant and/or lubricant is represented in the exemplary embodiment inFIG. 3with the aid of arrows64. In the preferably encapsulated bearing chamber26, the circulation of the lubricant situated there and thus also the cooling is promoted by the conveying effect of the bearing unit30. For this, the bearing unit30preferably comprises angular-contact ball bearings which preferably swirl the lubricant in the bearing chamber during their movement. The coolant and/or lubricant thereby flows through the cooling channels32and passes the cooling coil36. There thus arises a continuous circulation, so that a homogeneous temperature distribution comes about. Furthermore—supported by the conveying effect of the bearing unit30—no dead spaces arise in which the coolant and/or lubricant can linger. Furthermore, by means of the cooling coil36, the coolant and/or lubricant is cooled in the bearing chamber26. Together, this effects a lubrication as well as a cooling of the spindle nut14and the bearing unit30.

In the exemplary embodiment ofFIG. 3, the cooling of the cooling coil36is separate from the circulation of the coolant and/or lubricant in the bearing chamber26. Water, for example, is used as the coolant and/or lubricant for the cooling of the cooling coil36, whereas by contrast, the coolant and/or lubricant for the circulation is, for example, oil. As a result at least two cooling circuits separated from one another are provided. In the first circuit, for example, water is used as the coolant and/or lubricant and via the lance20cools the spindle12, thereafter via the cooling coil36, the spindle nut14and the bearing chamber26, and finally the motor18. For the second cooling circuit, for example, oil is used as the coolant and/or lubricant. The oil circulates in the bearing chamber26and is cooled by the cooling coil36. In addition, apart from the cooling, the oil effects a lubrication of the spindle nut14and the bearing unit30also. Both cooling circuits are preferably configured as, for example, a series and/or parallel connection.

In principle, it is however also conceivable that as an alternative, the cooling of the cooling coil36and the circulation in the bearing chamber26are not separated from one another and as a common coolant and/or lubricant, for example, oil is used. In this case, there is only one cooling circuit. For example, the “cold” oil as the coolant and/or lubricant then first causes cooling via the lance20, the spindle12, then via the cooling coil36, the spindle nut14and thereafter is used for the circulation in the bearing chamber26, and finally for cooling the motor18. It is however also conceivable that there is a separate cooling circuit for each individual part of the cooling circuits. For example, there is a separate cooling circuit for the spindle12, the spindle nut14, the cooling coil36, the bearing chamber26, the bearing unit30and the motor18.

In a particularly preferred exemplary embodiment, the cooling of the cooling coil36is integrated into the cooling path between, for example, the spindle12and the motor18. For example, water is provided as the coolant and/or lubricant. For example, the coolant and/or lubricant is fed first by means, for example, of a series connection to the lance20, thereafter to the cooling coil36and lastly to the motor18. This results in a cooling path from the spindle12via the spindle nut14to the motor18. In principle, however, any other arrangement of the cooling path is also conceivable. The circulation of the coolant and/or lubricant, for example, oil, in the bearing chamber26is separate from the cooling path in this exemplary embodiment.

What the different cooling paths therefore have in common is that a systemically and also thermally optimized heat removal from different heat sources takes place in a manner that is targeted and is adaptable to the respective requirements.

The overall spindle unit10is preferably configured as a planetary roller screw drive, whereby a high degree of precision and good force transmitting properties with a relatively high packing density characterise the spindle unit10.

According toFIGS. 3 and 4, the bearing element16is preferably configured as a separate element and is not integrated into the support element54and is not a component thereof. This results in easy assembly and due to the decoupling between the bearing element16and the support element54, no additional transverse forces act upon the bearing element16due to the deformation of the support element54.

In the exemplary embodiment ofFIGS. 3 and 4, the support element54has additional radial support means62for advantageous gravity compensation.

Preferably, the spindle nut14and/or the bearing chamber26has at least one cooling coil36. The heat quantity arising can thus advantageously be efficiently released and the spindle nut14can be cooled and/or temperature-controlled.

Where, in the context of this application, reference is made to temperature control, this also includes, in principle, a cooling. Usually, cooling also takes place.

It is self-evident that this description can be subject to a great variety of modifications, amendments and adaptations, which belong within the scope of equivalents to the accompanying claims.

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