Patent Description:
In the field of injection moulding machines, having an injection unit and a clamping unit for operating a mould box, the mould box typically comprises two mould plates (also called half plates) arranged moveably relative to each other and guided by a set of guide rail, which is hereinafter referred to as main guide rails, main guide rail pillars, main guide rail system or main guide rail pillar system to distinguish from any other guide mechanisms of injection moulding systems. The clamping unit further comprises a linear drive mechanism for pressing at least one of the mould plates against one or more other mould plates, during injection of molten plastic performed by the injection unit. The main guide rails are configured for supporting the mould plates, while the linear drive mechanism presses the plates together and when the mould plates are moved towards each other or away from each other.

Typically, one mould-plate is fixed relative to a frame of the injection moulding machine. In typical injection moulding machines , one or more mould plates is/are slideable along the set of main guide rails, which may also be referred to as main guide rail pillars. The moveable mould plates are commonly slideably translatable on four cylindrical guide rails arranged in parallel and intersecting the four corners of the square or rectangular mould plates. An actuator/linear drive mechanism drives the sliding of moveable mould-plate(s) along the set of guide rails, between a position, where the mould-plates closes to form a mould, and a position, where the mould-plates are separated from each other, so that a moulded item may be removed from the mould box.

The use of a set of four cylindrical main guide rail pillars provides for making a very stable construction. It is however a disadvantage that such mould box constructions are very complicated and expensive to manufacture due to the high precision needed for making the mould-plates slide on the set of parallel guide rail pillars, driving tight tolerance demands. Further, during use, mould boxes are subject to uneven temperature distribution, causing uneven wear on the mould box parts. It is also a problem that the guide rails makes it difficult to design for auxiliary functions for example ejection pins, extraction arms etc..

In the mould boxes of clamping unit of some injection moulding machines, in order to secure correct alignment of the mould plates, when the mould plates are moved together, in addition to the main guide rail pillars, it is known to provide an additional alignment or positioning system. Such as system may for example comprise a conical protrusion extending from one mould plate and a complementary conical indention formed in the opposing mould plate. When the mould plates are mowed towards each other, the interacting conical surfaces will align the mould plates. It is also known in the art, that such alignment systems comprises mating parts of other shapes. The German utility model, <CIT> discloses an example where the alignment system shows to beams of rectangular cross section. <CIT> discloses a locating device of a refrigerator pull plate mould. The locating device comprises a base and a locating cover plate, wherein a first plum-blossom-shaped locating hole is formed in the centre of the locating cover plate; second square locating holes are respectively formed in two sides of the first locating hole; a plum-blossom-shaped locating cylinder is arranged in the centre of the base; square locating strips are respectively arranged on two sides of the locating cylinder; the locating cylinder is matched with the first locating hole; and the square locating strips are matched with the second locating holes. According to the utility model, the plum-blossom-shaped locating cylinder is matched with the first plum-blossom-shaped locating hole; simultaneously, the square locating strips are matched with the second locating holes, and therefore, the locating precision of the mould is greatly increased; the precision and the reliability of a plastic part of a pull plate are also greatly increased; and the locating device of the refrigerator pull plate mould disclosed by the utility model is simple in structure, convenient to correct and high in practicability. <CIT> discloses that each mold half is associated with an adapter plate (<NUM>, <NUM>). This is fastened in turn, to the respective mold clamping platen. Detachable clamps (<NUM>, <NUM>') are fitted between the cavity mold (<NUM>) and the adapter plate (<NUM>) which carries it, and between the core plate (<NUM>) and the adapter plate (<NUM>) which carries it. They are fitted to the core (if used). The detachable clamps form connectors between the respective components. Couplings are included for connecting lines, the injection nozzle and the hot channel. Detachable connections are provided for drives actuating slides and/or ejectors. The arrangement of all connectors is such that, after releasing clamps, contour elements (i.e. mold and/or core) can be withdrawn from the adapter plates, hot channel and if appropriate, the core plate. The mold components (<NUM>, <NUM>) fitted to at least one of the adaptor plates, can then be slid on guides (<NUM>, <NUM>) in the direction of opening and closure. Through connections to their drive units, the adapter plates are brought sufficiently far apart to allow them to be lifted up from the guides, to permit mold exchange. Further mechanical details of the arrangement are described in accordance with the foregoing principles. An independent claim IS INCLUDED FOR the method of mold replacement. <CIT> discloses mold plate body on both sides of the plate body respectively to the coalesced sealed to form together with the molding cavity plate body outer and the molding die having a plate member is at a click and a passage open to the surface other, the passage from the opening provided in the branch and a branch passage, the branch passage having therein said cavity from the gate, on the other hand, leading to one end of the sprue is made and closed, the other end portion of the passage tightly fitted so as to slide the shaft has been runner shaft provided in the other end of the opening of the discharge port the branch "n are respectively provided, characterized in that if a molding die. <CIT> discloses a runner plate for an injection molding system comprises a plate typically having a plurality of corners, and typically apertures extending through the plate for receiving leader pins of the molding system for support of the plate in the molding system. Also at least a pair of outrigger supports may be provided, the outrigger supports being carried by the plate, each at a different position on the plate, and typically extending diagonally outwardly relative to adjacent plate edges. Also the outrigger support may carry rollers which are positioned to engage tie bars of the mold press for rolling contact therewith and support of the system. A mold which contains the runner plate may, by this invention, have leader pins that are longer than corresponding pins of the prior art, extending through the entire mold from, typically, the mold core on one side of the mold to a mold core on the other side of the mold, in the case of double action molds, with the leader pins being long enough to extend through the entire mold even in the open position, for added support. In such a circumstance, the outrigger supports may be dispensed with. <CIT> discloses, in a stack mold comprising a center mold part, first and second outside mold parts moveable at both sides of the center mold part, a rack and pinion gear arrangement to move the outside mold parts. The rack and pinion gear arrangement comprises a plurality of pinion gears located at the center mold part and including a drive gear and first and second follower gears driven off the drive gear. Also provided are first and second free ended racks extending in opposite directions from the first and second outside mold parts respectively in engagement with the first and second follower gears. These follower gears reach above and below the drive gear and the first follower gear is offset to the side of the drive gear opposite that to which the free end of the first rack extends while the second follower gear is offset to the side of the drive gear opposite that to which the free end of the second rack extends.

It is therefore an object of the invention to solve the disadvantages of the prior art systems, and to increase the variety of options.

In a first aspect the objects of the invention are achieved by a mould box for an injection moulding machine, the mould box comprising.

In an embodiment the rectangular shape of the main guide rail pillar is oriented such that a longer side of the rectangular shape extends vertically and a shorter side of the rectangular shape extends horizontally.

In a further embodiment, the guide track is formed in a sidewall of the main guide rail pillar which is a longer side of the rectangular shape of the cross-section of the main guide rail.

In either of the previously disclosed embodiments, the protruding bearing element may further have a length which is longer than a thickness of the second mould plate.

This will allow to increase the stiffness of the connection between the main guide rail pillar and the second mould plate along the longitudinal axis of the main guide rail pillar, and to thereby counteract torsion/rotation about an axis perpendicular to the longitudinal axis. Thereby, the risk of locking between the second mould plate and the main guide rail pillar is considerably reduced.

In embodiments hereof, the length of the protruding bearing element <NUM> to <NUM> times the thickness of the second mould plate.

Preferably, the length of the protruding bearing element is twice the thickness of the second mould plate.

In further embodiments, the protruding bearing element comprises a first roller bearing configured for rolling on said first internal guide surface of the guide track.

The first roller bearing may comprise on or more rollers, for example in the form of wheels, cylinders, balls, caterpillars or the like.

Preferably, the first internal guide surface of the guide track and the first roller bearing cooperating therewith are arranged horizontally. Thereby, the first internal guide surface of the guide track and the first roller bearing may support the vertical forces on the second main guide rail pillar from the mould plate.

In some embodiments, the protruding bearing element may further comprise a second roller bearing configured for rolling on a second internal guide surface of the guide track, wherein the second internal guide surface of the guide track is opposite to and facing the first internal guide surface of the guide track. The second roller bearing may - as the first roller bearing - comprise on or more rollers, for example in the form of wheels, cylinders, balls, caterpillars or the like.

Alternatively to the above mentioned embodiments comprising a roller bearing connection, the protruding bearing element may comprise a first external bearing surface configured for sliding against said first internal guide surface of the guide track.

Preferably, the first internal guide surface <NUM> of the guide track <NUM> and the first external bearing surface <NUM> are horizontally arranged. Thereby, the first internal guide surface of the guide track and the first external bearing surface may carry the vertical forces on the second mould plate.

In a further embodiment, the guide track comprises at least a second internal guide surface arranged opposite to and facing the first internal guide surface; and wherein the protruding bearing element comprises a second external bearing surface configured for sliding against said second internal guide surface of the guide track.

This provides an additional bearing contact between the main guide rail pillar and the second mould plate <NUM>, and prevents movement between the two in the vertical direction.

In further embodiments, the bearing further comprises a first internal bearing component arranged in the third opening through the bearing, wherein the first internal bearing component is configured to cooperate with one planar guide surface of the main guide rail pillar.

Thereby an additional bearing to the bearing between the internal guide track and the protruding bearing element is provided.

In a preferred embodiment thereof, at least the first internal bearing component of the bearing cooperates with a first planar guide surface, which is arranged perpendicular to the first guide surface of the guide track. Thereby the bearing provides support in the horizontal plane perpendicular to the longitudinal direction.

In a further embodiment, the first internal bearing component comprises a first internal bearing surface configured for sliding against the planar guide surface of the main guide rail pillar. Alternatively, the first internal bearing component may comprise a roller bearing connection.

In a further embodiment the bearing further comprises a second internal bearing component arranged in the third opening through the bearing, wherein the second internal bearing component is configured to cooperate with another one of the planar guide surfaces of the main guide rail pillar, which is also perpendicular to the first guide surface of the guide track and wherein the second internal bearing component is opposite to and facing the first internal bearing component. Thereby, the main guide rail pillar is prevented against horizontal movement perpendicularly to the direction of the longitudinal axis.

In a further embodiment, the second internal bearing component comprises a second internal bearing surface configured for sliding against the second planar guide surface of the main guide rail pillar. Alternatively, the second internal bearing component may comprise a roller bearing connection.

In a further embodiment, the bearing comprises a third internal bearing component arranged in the third opening through the bearing, wherein the third internal bearing component is configured to cooperate with another one of the planar guide surfaces of the main guide rail pillar, which is parallel to the first guide surface of the guide track. This may support the bearing between the main guide rail pillar and the second mould plate in the same direction as the bearing contact between the protruding bearing element and the first guide surface of the guide track.

In a further embodiment, the third internal bearing component comprises a third internal bearing surface configured for sliding against the third planar guide surface of the main guide rail pillar. Alternatively, the third internal bearing component may comprise a roller bearing connection.

In a further embodiment, the bearing may additionally comprise a fourth internal bearing component arranged in the third opening through the bearing, wherein the fourth internal bearing component is configured to cooperate with a fourth planar guide surfaces of the main guide rail pillar, which is parallel to the third planar guide surfaces and facing in the opposite direction thereto. This may prevent movement between the main guide rail pillar and the second mould plate in the same direction as the bearing contact between the protruding bearing element and the first guide surface of the guide track.

In a further embodiment thereof, the fourth internal bearing component comprises a fourth internal bearing surface configured for sliding against the fourth planar guide surface of the main guide rail pillar. Alternatively, the fourth internal bearing component may comprise a roller bearing connection.

In a further embodiment, the main guide rail system of the mould box may comprise a first main guide rail pillar, and second main guide rail pillar, and wherein each of the first and second main guide rail pillars has a rectangular cross section perpendicular to the longitudinal axis. In a further embodiment hereof, the first main guide rail pillar extends through an opening in the second mould plate, where said opening through the second mould plate is formed centrally adjacent to an upper edge of the second mould plate, and wherein the second main guide rail pillar extends through another opening in the second mould plate, which opening is formed centrally adjacent to a lower edge of the second mould plate.

However, the main guide rail system of the mould box may alternatively comprise a single main guide rail pillar only. In this case, preferably, the single main guide rail pillar extends through a second opening in the second mould plate, which said opening through the second mould plate is formed centrally in the second mould plate.

In a second aspect the objects of the invention are achieved by an injection moulding machine comprising a mould box according to the first aspect of the invention.

More particularly, in the second aspect, the objects of the invention are achieved by an injection moulding machine comprising.

wherein the second mould plate is movably arranged relative to the first mould plate, and driven by the linear drive mechanism.

It should be emphasized that the term "comprises/comprising/comprised of" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

<FIG> illustrates schematically an injection moulding machine <NUM> as known in the art. The injection moulding machine <NUM> generally comprises an injection part <NUM>, shown in the left side of the figure, and a clamping part <NUM>, shown in the right side of the figure. The injection part <NUM> handles injection of plastic material into a mould formed in the clamping part <NUM> of the injection moulding machine <NUM>. The injection part <NUM> and the clamping part <NUM> of the injection moulding machine <NUM> are attachable to a mount <NUM>.

Injection moulding machines <NUM> generally works in the following way: Plastic granules <NUM> are fed into the barrel <NUM> of a reciprocating screw <NUM> of the injection part <NUM> via a hopper <NUM>. The reciprocating screw <NUM> is driven by a drive mechanism <NUM>, such as an electrical motor. The plastic granules <NUM> fed through the hopper <NUM> are then transported towards the clamping part <NUM> by the reciprocal screw, while being compacted and they are heated by heating devices <NUM> surrounding the reciprocating screw <NUM>, until they melt and reach a suitable viscosity at a nozzle <NUM> at the entrance to the clamping part <NUM> with the mould. The mould is formed in a mould box <NUM>.

The fluid plastic material is fed from the nozzle <NUM> through sprue channels <NUM> in a base plate <NUM> of the mould box <NUM>, and reaches a mould cavity <NUM> formed in a first mould plate <NUM> of the mould box <NUM>. The first mould plate <NUM> of the mould box <NUM> is connected to the base plate <NUM>. The base plate <NUM> is connected to the mount <NUM>. A second mould plate <NUM> of the mould box <NUM>, which may comprise a mould core and/or further portions of a mould cavity is arranged moveably relative to the first mould plate <NUM>, such that the mould box may be completely closed (clamped together) to allow injection of the melted plastic, and such that the mould box <NUM> may be opened to extract a moulded object <NUM> (see <FIG>). The first mould plate <NUM> and the second mould plate <NUM> of a mould box <NUM> may also be referred to as half plates. Thus, the first mould plate <NUM> of a mould box <NUM> may also be referred to as a first half plate, and the second mould plate <NUM> of a mould box <NUM>, may also be referred to as a second mould plate.

In <FIG> the second mould plate <NUM> is attached to a moveable platen <NUM>. The moveable platen <NUM> - and thereby the second mould plate <NUM> - is slideably arranged on a set of cylindrical main guide rails <NUM>. Typically, the clamping part <NUM> of injection moulding machines <NUM> comprises four cylindrical main guide rails <NUM> for guiding the movement of the moveable platen <NUM> with the second mould plate <NUM>. The movement of the moveable platen <NUM> with the second mould plate <NUM> is performed by a linear drive mechanism <NUM>, typically a hydraulic mechanism.

The moveable platen <NUM> with the second mould plate <NUM> comprises through-going slide bearings, slidably receiving the cylindrical main guide rails <NUM>.

In an injection process, the linear drive mechanism <NUM> clamps the first mould plate <NUM> and the second mould plate <NUM> together, whereupon plastic is injected from the reciprocal screw <NUM> through the nozzle <NUM> and into the mould cavity <NUM>. When the plastic has filled the mould cavity <NUM> completely, and has cooled sufficiently for the plastic to be in solid state, then the linear drive mechanism <NUM> moves the second mould plate <NUM> away from the first mould plate <NUM>, and the moulded object is ejected from the mould cavity <NUM> in the first mould plate <NUM>. The ejection of the moulded object <NUM> is typically done by ejector pins (not shown) formed in/through the base plate <NUM>.

<FIG> shows a prior art mould box <NUM> for an injection moulding machine <NUM> (as outlined in <FIG>), and a moulded object <NUM>. The mould box <NUM> is shown in a separated state where the moulded object <NUM> is visible between two half plates, or mould plates <NUM>, <NUM> of the mould box <NUM>. Thus, the he mould box <NUM> comprises two mould plates <NUM>, <NUM>. A first mould plate <NUM>, here shown to comprise a mould cavity <NUM> of a mould, is connected to a base plate <NUM> of the mould box <NUM>. The first mould plate <NUM> and the base plate <NUM> may form one integrated part, or they may be formed as separate parts and joined subsequently by suitable means, e.g. bolts. A mould cavity <NUM> is formed as a depression in a surface of the first mould plate <NUM>.

The first mould plate <NUM> is - via the base plate <NUM> -connected to an injection moulding machine <NUM>, e.g. as described above. The base plate <NUM> may thus be connected to a mount <NUM> as shown in <FIG>.

A second mould plate <NUM> is moveably arranged relative to the first mould plate <NUM> and the injection moulding machine <NUM>. The second mould plate <NUM> is slideably arranged on a set of cylindrical main guide rails <NUM> of a main guide rail system configured for guiding the second mould plate <NUM> linearly away from and towards the first mould plate <NUM>.

The set of cylindrical main guide rails <NUM> comprises four cylindrical main guide rails <NUM>. The cylindrical main guide rails <NUM> are arranged to slide over bearings (not shown) provided through the second mould plate <NUM>, or through a moveable platen <NUM> to which the second mould plate <NUM> is mounted. In <FIG> only a portion of the cylindrical main guide rails <NUM> is seen.

The cylindrical main guide rails <NUM> are fixedly secured in the openings <NUM> provided in the first mould plate <NUM>. There is one opening <NUM> per main guide rail <NUM>.

In <FIG> the main guide rails extend through the second mould plate <NUM> itself, as opposed to the version shown in <FIG>, where the second mould plate <NUM> is connected to a moveable platen <NUM>, which has bearings for the cylindrical main guide rails <NUM>.

The second mould plate <NUM> is shown with a core <NUM> configured for mating with the mould cavity <NUM> in the first mould plate <NUM> to form a shape corresponding to the moulded object <NUM>.

<FIG> show a mould box <NUM> having a single, centrally arranged, rectangular cross section main guide rail pillar <NUM>, instead of the set of cylindrical main guide rails <NUM> shown in <FIG> and <FIG>. The present invention relates to such a rectangular cross-section main guide rail pillar <NUM>, which will first be described in the following, before the invention is described in detail further below.

The mould box <NUM> comprises a base plate <NUM> and a first mould plate <NUM> connected thereto. During use in injection moulding processes, the first mould plate <NUM> is fixed in position relative to the base plate <NUM>. The base plate <NUM> is fixedly connectable to an injection moulding machine, e.g. as described in connection with the prior art injection moulding machine <NUM> shown in <FIG>. The first mould plate <NUM> may comprise one or more mould cavities (not shown) formed as depressions in a first surface <NUM> of the first mould plate <NUM>. An opposite side, second side <NUM> of the first mould plate <NUM> faces the base plate <NUM>, see e.g. <FIG>.

The first mould plate <NUM> may be formed integrally with the base plate <NUM>, or it may - as shown in <FIG> - be formed as individual/separate parts and subsequently be joined/connected, such that the first mould plate <NUM> is fixed to the base plate <NUM> at least during the injection moulding process. The first mould plate <NUM> may be connected to the base plate <NUM> using for example bolts.

The not shown one or more mould cavities may - in also not shown - further embodiments be formed in one or more cassettes attachable on - or insertable in suitable recesses, e.g. in the first surface <NUM> of the first mould plate <NUM>.

Further, the first mould plate <NUM> and or the base plate <NUM> may be equipped with sprue channels <NUM> and runner channels (not shown in <FIG>) necessary to connect the one or more mould cavities in the first mould plate <NUM> with an injection nozzle <NUM> of an injection moulding machine <NUM>, such as an injection moulding machine as shown in <FIG>.

The mould box <NUM> shown in <FIG> further comprises a second mould plate <NUM>. The second mould plate <NUM> is movably arranged relative to the first mould plate <NUM>. Thereby, the second mould plate <NUM> is also movably arranged relative to the base plate <NUM>.

The mould box <NUM> as shown in <FIG> further comprises a main guide rail system <NUM>' configured for guiding the second mould plate <NUM> linearly away from and towards the first mould plate <NUM>.

The main guide rail system <NUM>' allows the second mould plate <NUM> to be movably arranged relative to the base plate <NUM>.

In other - not shown - embodiments, the first mould plate <NUM> may also be movably arranged, relative to the base plate <NUM>, the injection moulding machine <NUM> further comprising means for moving the first mould plate <NUM> on the main guide rail system <NUM>'.

In yet other - not shown - embodiments, the mould box <NUM> may comprise a third plate (not shown) arranged between the first mould plate <NUM> and the base <NUM>, where for example runner channels are arranged in third plate. Such a third plate may be fixed relative to the base plate <NUM> or it may be moveable on the main guide rail system <NUM>' in order to facilitate de-shaping of the runner channels.

As shown in <FIG>, the main guide rail system <NUM>' comprises a single main guide rail pillar <NUM>, only. In principle, the main guide rail system may <NUM>' may comprise more than a single main guide rail pillar, but only one is needed.

<FIG> illustrates an embodiment, where the mould box <NUM> comprises two main guide rail pillars <NUM>, a first main guide rail pillar <NUM> and a second guide pillar <NUM>. The first main guide rail pillar <NUM> extends through an opening <NUM> formed through a bearing <NUM> formed in the second mould plate <NUM>. This opening <NUM> through the bearing <NUM> of the second mould plate <NUM> is formed adjacent to an upper edge <NUM> of the second mould plate <NUM>, and centrally along this edge <NUM>. Further, the second main guide rail pillar <NUM> extends through another opening <NUM> through a second bearing <NUM> formed in the second mould plate <NUM>. This opening <NUM> is formed adjacent to a lower edge <NUM> of the second mould plate <NUM>, and centrally along this edge <NUM>.

Now returning to <FIG>, the main guide rail pillar <NUM> is elongate, having a first end <NUM> and second end <NUM>, an elongate body part <NUM> extending between the first end <NUM> and the second end <NUM>, and a longitudinal axis A. The main guide rail pillar <NUM> has a cross sectional shape perpendicular to the longitudinal axis A.

The cross-section/cross-sectional shape forms a polygon.

We note that by a polygon or polygonal shape we mean any <NUM>-dimensional shape formed with straight lines. Triangles, quadrilaterals, pentagons, and hexagons are all examples of polygons.

There are two main types of polygon - regular and irregular. A regular polygon has equal length sides with equal angles between each side. Any other polygon is an irregular polygon, which by definition has unequal length sides and unequal angles between sides. In principle, the cross-section of the guide pillar according to the invention may have any polygonal shape.

However, as shown in <FIG>, the polygonal shape may in preferred embodiments be rectangular or quadratic.

In some embodiments a longer side length of the rectangular cross section/cross-sectional shape may be arranged vertically. Thus, the rectangular shape of the main guide rail pillar <NUM> is oriented such that a longer side of the rectangular shape extends vertically and a shorter side of the rectangular shape extends horizontally.

In any case, each main guide rail pillar <NUM> having a cross-section/cross-sectional shape forming a polygon will result in the main guide rail pillar <NUM> having a set of planar guide surfaces <NUM>',<NUM>", <NUM>', <NUM>" for cooperating with a bearing element <NUM> arranged on the second mould plate <NUM>. The number of planar guide surfaces on the main guide rail pillar <NUM> will depend on the number of sides of the polygonal cross-section/cross-sectional shape of the main guide rail pillar <NUM>. The main guide rail pillar <NUM> shown in <FIG>, and <FIG> having a rectangular cross section has two wider planar guide surfaces <NUM>', <NUM>", and two narrower planar guide surfaces <NUM>', <NUM>". The two wider planar guide surfaces <NUM>', <NUM>" are parallel to each other and formed on opposed sides of the main guide rail pillar <NUM>. Similarly, the two narrower planar guide surfaces <NUM>', <NUM>" are parallel to each other and formed on opposed sides of the main guide rail pillar <NUM>, but perpendicular to the two wider planar guide surfaces <NUM>', <NUM>".

The second mould plate <NUM> may comprise one or more mould cores <NUM> (not shown in <FIG>) extending outward from a first surface <NUM> of the second mould plate <NUM>, facing the first surface of the first mould plate <NUM>. An opposite side, second surface <NUM> of the second mould plate <NUM> faces away from the first mould plate <NUM> and the base plate <NUM>, see e.g. <FIG>. The second mould plate <NUM> is arranged moveably relative to the first mould plate <NUM>, such that the mould box may be completely closed (clamped together) to allow injection of the melted plastic into a mould cavity formed between the first and second mould plates <NUM>, <NUM>, and such that the mould box <NUM> may be opened to extracted a moulded object, e.g. similar to the moulded object <NUM> shown in <FIG>.

As is the case with the first mould plate <NUM>, described above, the not shown one or more mould cores (and/or further portions of mould cavities) may - in also not shown - further embodiments be formed in one or more cassettes attachable on - or insertable in suitable recesses in e.g. the first surface <NUM> of the second mould plate <NUM>.

As is the case with the prior art examples described above, the mould box <NUM> according to the invention may form part of a clamping part <NUM> of an injection moulding machine <NUM>, in this case however with a single polygonal cross-section main guide rail pillar <NUM> (instead of the four cylindrical main guide rails <NUM>, shown in <FIG>) for guiding the movement of the second mould plate <NUM>. The movement of the second mould plate <NUM> is performed by a linear drive mechanism <NUM>, for example a hydraulic mechanism.

As shown in <FIG>, the main guide rail pillar <NUM> extends through a second opening <NUM> in the second mould plate <NUM>. The second opening <NUM> in the second mould plate <NUM> is a through-going opening extending all the way through the second mould plate <NUM>.

The second opening <NUM> in the second mould plate <NUM> preferably has a cross sectional shape corresponding to the cross-sectional shape of the guide pillar <NUM> such that the guide pillar <NUM> may be slidably arranged therein.

As shown in <FIG> and <FIG>, the main guide rail pillar <NUM> also may extend through a first opening <NUM> in the first mould plate <NUM>. The first opening <NUM> in the first mould plate <NUM> is a through-going opening extending all the way through the first mould plate <NUM>. The first opening <NUM> in the first mould plate <NUM> preferably has a cross sectional shape corresponding to the cross-sectional shape of the guide pillar <NUM> such that the guide pillar <NUM> may be received and fixedly anchored.

The main guide rail pillar <NUM> may have a main body part <NUM> and flange or protrusion <NUM> having a larger cross sectional extent than that of the main body part <NUM>, see e.g. <FIG>. In such cases, and as shown in e.g. <FIG>, the first opening <NUM> in the first mould plate <NUM> may comprise one first section <NUM> configured for receiving a portion of the main body part <NUM> of the main guide rail pillar <NUM>, and another, second section <NUM> with a larger cross-sectional extend than the first section <NUM>, and configured for receiving the flange <NUM> of the main guide rail pillar <NUM>, see e.g. <FIG>. The main guide rail pillar <NUM> at a first end <NUM> thereof may thereby be provided with a protrusion <NUM> configured for cooperating with an enlargement <NUM> of the second opening <NUM> in the first mould plate <NUM>. Thereby, the main guide rail pillar <NUM> may be anchored in first opening <NUM> through the first mould plate <NUM>.

In either case, and as shown in <FIG> the second opening <NUM> in the second mould plate <NUM> is formed centrally in the second mould plate <NUM>. In this case, it follows that the first opening <NUM> in the first mould plate <NUM> is also formed centrally in the first mould plate <NUM>.

In other embodiments, and as illustrated in <FIG>, a single main guide rail may not necessarily have to be arranged through a centrally located opening <NUM>, <NUM> in each mould plate <NUM>, <NUM>. <FIG> illustrates an embodiment, where a single main guide rail pillar <NUM> is arranged through a second opening <NUM> in the second mould plate <NUM>, which is located adjacent to a lower edge of the second mould plate <NUM>, and centrally on the lower edge <NUM>. It follows that in such embodiments, the first opening <NUM> through the first mould plate would be arranged in a similar manner (the first mould plate <NUM> is not shown in <FIG>).

The one or more mould cavities may be formed around the first opening <NUM> in the first mould plate <NUM>. Further, mating mould cores may be formed around the second opening in the movable, second mould plate <NUM>.

<FIG>, in various views, show a mould box <NUM> according to one embodiment of the invention in a first position, where the first and second mould plates <NUM>, <NUM> are in close contact and clamped together. This illustrates a position, where plastic may be injected into the (not shown) mould cavity formed between the first and second mould plates <NUM>, <NUM>. Correspondingly, <FIG> show the mould box of <FIG> in a second position, where the first and second mould plates <NUM>, <NUM> are separated from each other. This illustrates a position, where moulded objects may be removed from the mould cavity.

In either of the above mentioned cases, the second opening <NUM> in second mould plate <NUM> may, as shown, be provided with a bearing <NUM>, such as a slide bearing. In this case the second opening <NUM> in the second mould plate <NUM> may be configured to receive the bearing <NUM>.

The bearing <NUM> comprises a bearing element <NUM> with inner surfaces configured for contacting against the planar guide surfaces <NUM>', <NUM>", <NUM>', <NUM>" of the main guide rail pillar <NUM>. The bearing <NUM> may, as shown in <FIG>, have a main body part <NUM> and flange <NUM> having a larger cross sectional extent than that of the main body part <NUM>. In such cases the second opening <NUM> in the second mould plate <NUM> may comprise one first section <NUM> configured for receiving the main body part <NUM> of the bearing <NUM>, and another, second section <NUM> with a larger cross-sectional extend than the first section <NUM>, and configured for receiving the flange <NUM> of the bearing <NUM>, see e.g. <FIG>.

As shown in <FIG>, the main guide rail pillar <NUM> extends through a third opening <NUM> formed in the bearing <NUM>. The third opening <NUM> in the bearing <NUM> is a through-going opening extending all the way through the bearing <NUM>. The third opening <NUM> in the bearing <NUM> preferably has a cross sectional shape corresponding to the cross-sectional shape of the guide pillar <NUM> such that the guide pillar <NUM> may be may be slidably arranged therein.

In the embodiment shown in <FIG>, having two main guide rail pillars <NUM>, a bearing <NUM> as described above may be provided between each main guide rail pillar and the second mould plate <NUM>.

One problem with such a main guide rail pillar with a polygonal cross-shape is the torsional forces between the one, two of more main guide rail pillars <NUM> and the second mould plate <NUM>, and possibly further plates slideably arranged on the main guide rail pillar(s) <NUM>. During use, torsional forces are bound to affect the moveable second mould plate <NUM>. Such torsional forces may impart a slight tilting of the second mould plate <NUM> (and/or further plates) relative to the main guide rail pillar(s) <NUM>. This will result in increased wear of the bearing <NUM> (between the main guide rail <NUM> and the mould plate <NUM>) and/or main guide rail <NUM>, and in some cases there is even a risk that the second mould plate <NUM> will become locked to the main guide rail pillar(s) <NUM>.

Such a locking effect is illustrated in <FIG>, in the context of a prior art cylindrical main guide rail pillar <NUM> with a bearing <NUM> slidably arranged thereon. If pressure (indicated by arrow A' in <FIG> is supplied to the bearing (such as through a second mould plate) at a distance D from the main guide rail pillar <NUM> longitudinal axis, the bearing <NUM> may tilt slightly relative to the main guide rail pillar <NUM>. As indicated by arrows B' and C' such a slight torsion of the bearing <NUM> may cause surface portions of the bearing <NUM> to apply a larger pressure on the main guide rail pillar <NUM>. i.e. it will increase the friction in the Z direction, indicated in the figure at points or locations of the bearing <NUM>. This will increase wear on the bearing surfaces and on the main guide rail pillar <NUM>. In some cases it may even cause the bearing <NUM> (and thereby the movable second mould plate <NUM> being locked to the main guide rail pillar <NUM>, which is highly undesirable. This will happen when the frictional forces, in the Z-direction, between the bearing <NUM> and the main guide rail pillar <NUM> at the points/locations indicated by arrows B' and C' becomes larger than the forces A' applied in the Z direction. This may be termed a lock effect or locking effect.

In <FIG>, such a lock effect is explained in connection with a prior art cylindrical main guide rail pillar <NUM>. It will however be appreciated that there is a risk of a similar occurrence of a lock effect (or increased wear) in connection with the polygonal, such as rectangular, main guide rail pillars as described above.

The present invention, decreases this problem.

In one aspect of the invention this may be overcome by the main guide rail pillar(s) <NUM> having a rectangular cross section with the longer side surfaces being arranged vertically, such as is shown in e.g. <FIG>, where the main guide rail pillar(s) has/have a rectangular cross section with two wider planar guide surfaces <NUM>', <NUM>", and two narrower planar guide surfaces <NUM>', <NUM>". The two wider planar guide surfaces <NUM>', <NUM>" are parallel to each other and formed on opposed sides of the main guide rail pillar <NUM>. Similarly, the two narrower planar guide surfaces <NUM>', <NUM>" are parallel to each other and formed on opposed sides of the main guide rail pillar <NUM>, but perpendicular to the two wider planar guide surfaces <NUM>', <NUM>".

However, it has shown that there may be a need for further guidance for stabilizing the movement of the second mould plate <NUM> or any other platen moving on the main guide rail pillar <NUM>. A solution to this problem is shown in the <FIG>.

The embodiments shown in <FIG> also concerns a mould box <NUM> for an injection moulding machine, such as the injection moulding machine <NUM> shown in <FIG>. The mould box <NUM> also in this case comprises a first mould plate <NUM> and second mould plate <NUM>, where at least the second mould plate <NUM> is movably arranged relative to the first mould plate <NUM> along the longitudinal axis, A, along a main guide rail system <NUM>.

As descried above the main guide rail system is configured for guiding at least the second mould plate <NUM> linearly away from and towards the first mould plate <NUM>, and the main guide rail system <NUM>' may comprise one or more main guide rail pillar(s) <NUM>, in the same way as described above. Also as described above, each of main guide rail pillar(s) <NUM> may have a cross section perpendicular to the longitudinal axis (A), which is rectangular.

The invention differs from what is described above, by having a guide track <NUM> formed in a sidewall of the main guide rail pillar <NUM>. The guide track <NUM> is formed as an elongate indention into one sidewall of the rectangular main guide rail pillar <NUM>. The guide track <NUM> extends along an entire length of the main guide rail pillar <NUM> in the longitudinal direction, defined by the longitudinal axis, A, thereof, or at least over a distance, where the second mould plate <NUM> is intended to be slidably translational. The guide track <NUM> comprises at least one guide surface, first guide surface <NUM>. The first guide surface <NUM> can be seen in <FIG> is a side view of the embodiment shown in <FIG>, and <FIG> is sectional view through the same.

As shown in e.g. <FIG> and <FIG>, as also described above each main guide rail pillar <NUM> extends through a third opening <NUM> formed through a bearing <NUM> arranged between each main guide rail pillar <NUM> and the second mould plate <NUM>. In <FIG> and <FIG>, the bearing <NUM> is shown in perspective, from two different sides of the rectangular main guide rail pillar <NUM>, respectively. <FIG> and <FIG> shows the main guide rail <NUM>, bearing <NUM> and second mould plate <NUM> in an assembled state, where the bearing <NUM> is slidably arranged on/connected to the main guide rail pillar <NUM>. <FIG>, <FIG> shows the same as <FIG>, <FIG>, respectively, but where the main guide rail <NUM> is disassembled from the bearing <NUM> and the second mould plate <NUM>.

A protruding bearing element <NUM> extends from the third opening <NUM> formed in the bearing <NUM> and into the guide track <NUM>. The protruding bearing element <NUM> is connected to a bearing element <NUM> of the bearing <NUM> or to the second mould plate <NUM>. As shown in <FIG>, the protruding bearing element <NUM> may be formed by two parallelly arranged rollers <NUM>. Other embodiments of the protruding bearing element <NUM> will be described below in connection with <FIG>.

Regardless, the protruding bearing element <NUM> forms a bearing contact against the first guide surface <NUM> of the guide track <NUM>.

As shown in <FIG>, the main guide rail pillar <NUM> extends through a third opening <NUM> through a bearing <NUM>, which may be arranged in a second opening <NUM> formed through the second mould plate <NUM>, in the same manner as described previously. Thus, in such embodiments, the bearing <NUM> comprises a separate bearing unit, comprising having a bearing element <NUM> which is separate from the second mould plate <NUM>. However, in other - not shown embodiments - at least some portions of the bearing <NUM> arranged between the main guide rail pillar <NUM> and the second mould plate <NUM> may be connected directly to portions of the second mould plate <NUM>. For example, the protruding bearing element <NUM> may be connected directly to the second mould plate <NUM>.

The rectangular cross sectional shape of the main guide rail pillar <NUM> may - in not shown embodiments - comprise equal side lengths, i.e. the cross sectional shape is square. However, as also described above, and in order to reduce the risk tilting of the second mould plate <NUM> relative to the main guide rail pillar, the rectangular shape of the main guide rail pillar <NUM> is oriented such that a longer side of the rectangular shape extends vertically and a shorter side (relative to the vertical sides) of the rectangular shape extends horizontally.

The guide track <NUM> is preferably, and as shown in all of <FIG>, formed in a sidewall of the main guide rail pillar <NUM>, which is a longer side of the rectangular shape of the cross-section of the main guide rail <NUM>.

As mentioned and as shown in <FIG>, in some embodiment the protruding bearing element comprises a first roller bearing <NUM> configured for rolling on said first internal guide surface <NUM> of the guide track <NUM>. The first roller bearing <NUM> may comprise on or more rollers <NUM>, for example in the form of wheels, cylinders, balls, caterpillars or the like. In <FIG> the first roller bearing <NUM> is provided by two rollers <NUM> in the form of wheels, configured for cooperation with the first internal guide surface <NUM>, which as shown in <FIG> is arranged horizontally. Thereby, the first internal guide surface <NUM> of the guide track <NUM> and the first roller bearing <NUM> may carry the vertical forces on the second mould plate <NUM> and the main guide rail pillar <NUM>.

It will be appreciated that is some - not shown -embodiments, the protruding bearing element <NUM> may in addition to the first roller bearing <NUM> shown also comprise a comprise a second roller bearing configured for rolling on a second internal guide surface of the guide track <NUM>. The second internal guide surface of the guide track <NUM> is arranged opposite to and facing the first internal guide surface <NUM> of the guide track <NUM>. The second roller bearing may - as the first roller bearing <NUM> - comprise on or more rollers, for example in the form of wheels, cylinders, balls, caterpillars or the like. This would provide an additional bearing contact between the main guide rail pillar <NUM> and the second mould plate <NUM> and prevent the two from movement in the vertical direction (Y-direction in <FIG>, <FIG>).

As an alternative to the one or more roller bearings <NUM> between the guide track <NUM> formed in the main guide rail pillar <NUM> and the protruding bearing element <NUM> connected to the second mould plate <NUM>, sliding bearings may be provided. Examples of this will be described with reference to <FIG> and <FIG>.

In <FIG> and <FIG>, the protruding bearing element <NUM> is formed as a block of material extending from an internal sidewall/side surface of the third opening <NUM> through the bearing element <NUM> forming the bearing <NUM> between the main guide rail pillar and the second mould plate <NUM>. The protruding bearing element <NUM> comprises a first external bearing surface <NUM> configured for sliding against the first internal guide surface <NUM> of the guide track <NUM>.

In this case, as shown in the <FIG> and <FIG>, preferably, the first internal guide surface <NUM> of the guide track <NUM> and the first external bearing surface <NUM> are horizontally arranged. Thereby, the first internal guide surface <NUM> of the guide track <NUM> and the first external bearing surface <NUM> may carry the vertical forces on the second mould plate <NUM>.

As it is also shown in <FIG> and <FIG>, the protruding bearing element <NUM> is formed as a block of material extending from an internal sidewall/side surface of the third opening <NUM> through the bearing element <NUM> may - in some embodiments additionally or alternatively comprise a second external bearing surface <NUM> arranged opposite to and facing away from the first external bearing surface <NUM>. Also, the guide track <NUM> in this instance comprises at least a second internal guide surface <NUM>, which is arranged opposite to and facing the first internal guide surface <NUM> of the guide track <NUM>. The second external bearing surface <NUM> is configured for sliding against said second internal guide surface <NUM> of the guide track <NUM>.

This would provide an additional bearing contact between the main guide rail pillar <NUM> and the second mould plate <NUM> and lock the two against movement in the vertical direction.

We note that in as shown and described above, a length, L, of the bearing <NUM> in the direction along the longitudinal axis, A, coincides with a thickness, T, (illustrated in <FIG>) of the second mould plate <NUM>. Thus, the ends of the bearing element <NUM> in such embodiments are flush with the first and second surface <NUM>, <NUM> of the second mould plate <NUM>.

However, in some embodiments, and as shown in <FIG>, the bearing element <NUM> may be provided with a flange <NUM> extending in the direction along the longitudinal axis, A, and protruding away from the second surface <NUM> of the second mould plate <NUM>, such that a length of the protruding bearing element <NUM> and thereby the length of the first and/or second external bearing surfaces <NUM>, <NUM>, may be elongated relative to the previously described embodiment. This will allow to increase the stiffness of the connection between the main guide rail pillar <NUM> and the second mould plate <NUM> along the longitudinal axis A, and to thereby counteract torsion/rotation about the X-direction indicated in <FIG>, i.e. reduce the lock effect described in connection with <FIG> above.

We note that even though, such an elongation of the protruding bearing element <NUM> has been described in connection with a sliding bearing, such as shown in <FIG> and <FIG>, a similar elongation of the protruding bearing element <NUM> may be provided in cases - as described above - with first and/or second roller bearings <NUM>.

Thus, more generally speaking, the protruding bearing element <NUM> may have a length, L, which is longer than a thickness, T, of the second mould plate <NUM>.

In general, the relationship between the length, L, of the protruding bearing element <NUM> and the thickness, T, of the second mould plate <NUM> is adapted to reduce the lock effect. The guide track <NUM> as such and in particularly in combnation with either additional guide surfaces and/or an increased length L of the bearing, allows thinner mould plates <NUM> (reduction of T), and thereby to reduce the weight of mould boxes <NUM>.

In one embodiment, the length, L, of the protruding bearing element <NUM> is twice the thickness, T, of the second mould plate <NUM>.

Above, the bearing connection between the protruding bearing element <NUM> and the guide track <NUM> has been described.

In addition thereto it is possible to provide further bearing connections between the outer surfaces of the main guide rail pillar <NUM> and internal surfaces of the third opening <NUM> formed through the bearing element <NUM>. This will increase the relative stability of the connection between the main guide rail pillar <NUM> and the second mould plate <NUM>.

Thus, in some embodiments the bearing <NUM> further comprises a first internal bearing component <NUM>', <NUM>", <NUM>', <NUM>" arranged in the third opening <NUM>, which is provided through the bearing <NUM>, wherein the first internal bearing component <NUM>', <NUM>", <NUM>', <NUM>" is configured to cooperate with one of the planar guide surface <NUM>', <NUM>", <NUM>', <NUM>" of the main guide rail pillar <NUM>. The first internal bearing component <NUM>', <NUM>", <NUM>', <NUM>" may be a roller bearing comprising on or more rollers <NUM>, for example in the form of wheels, cylinders, balls, caterpillars or the like. In other embodiments the first internal bearing component <NUM>', <NUM>", <NUM>', <NUM>" may be a sliding bearing.

In a preferred embodiment, at least the first internal bearing component <NUM>' of the bearing <NUM> cooperates with a first planar guide surface <NUM>', <NUM>", which is perpendicular to the first guide surface <NUM> of the guide track <NUM>. Thereby the bearing provides support in the horizontal plane.

In one embodiment thereof, the first internal bearing component <NUM>' comprises a first internal bearing surface <NUM>' configured for sliding against the planar guide surface <NUM>', of the main guide rail pillar <NUM>. This is shown in <FIG> and in <FIG>. Alternatively, the first internal bearing component <NUM>' may comprise a roller bearing connection (not shown).

In a further embodiment the bearing <NUM> may additionally comprises a second internal bearing component <NUM>" arranged in the third opening <NUM> through the bearing <NUM>. The second internal bearing component <NUM>" is configured to cooperate with another one of the planar guide surfaces, second planar guide surface <NUM>" of the main guide rail pillar <NUM>. The second planar guide surface <NUM>" is also perpendicular to the first guide surface <NUM> of the guide track <NUM>. The second internal bearing component <NUM>" is arranged opposite to and facing the first internal bearing component <NUM>'. Thereby, the second mould plate <NUM> is prevented from movement relative to the main guide rail pillar <NUM> in the horizontal direction (along X in <FIG>).

In one embodiment hereof, the second internal bearing component <NUM>" comprises a second internal bearing surface <NUM>" configured for sliding against the second planar guide surface <NUM>" of the main guide rail pillar <NUM>, as shown in <FIG> and <FIG>. Alternatively, the second internal bearing component <NUM>" may comprise a roller bearing connection (not shown).

In some further embodiments, the bearing <NUM> may further comprise a third internal bearing component <NUM>' arranged in the third opening <NUM> through the bearing <NUM>. The third internal bearing component <NUM>' is configured to cooperate with another one of the planar guide surfaces <NUM>' of the main guide rail pillar <NUM>, which is parallel to the first guide surface <NUM> of the guide track <NUM>. This may support the bearing connection between the main guide rail pillar <NUM> and the second mould plate <NUM> in the same direction as the bearing contact between the protruding bearing element <NUM> and the first guide surface <NUM> of the guide track <NUM>.

In an embodiment hereof, the third internal bearing component <NUM>' comprises a third internal bearing surface <NUM>', <NUM>" configured for sliding against the third planar guide surface <NUM>' of the main guide rail pillar <NUM>, as shown in <FIG>. Alternatively, the third internal bearing component <NUM>' may comprise a roller bearing connection (not shown).

Additionally, in a further embodiment, the bearing <NUM> may comprise a fourth internal bearing component <NUM>", also arranged in the third opening <NUM> through the bearing <NUM>. The fourth internal bearing component <NUM>" is configured to cooperate with a fourth planar guide surfaces <NUM>" of the main guide rail pillar (<NUM>), which is parallel to the third planar guide surfaces <NUM>' and facing in the opposite direction thereto. This may prevent the bearing connection between the main guide rail pillar <NUM> and the second mould plate <NUM> from movement in the same direction as the bearing contact between the protruding bearing element <NUM> and the first guide surface <NUM> of the guide track <NUM>, i.e. the vertical direction, which is the Y-direction in <FIG>.

In an embodiment hereof, the fourth internal bearing component <NUM>" comprises a fourth internal bearing surface <NUM>" configured for sliding against the fourth planar guide surface <NUM>" of the main guide rail pillar <NUM> as shown in <FIG>. Alternatively, the fourth internal bearing component <NUM>" may comprise a roller bearing connection (not shown).

We note that in any of the embodiments where the main guide rail pillar <NUM> is described with a guide track (<FIG>), the main guide rail system <NUM>' of the mould box <NUM> may comprises a first main guide rail pillar <NUM>, and second main guide rail pillar <NUM>, in the same manner as shown in <FIG>, where each of the first and second main guide rail pillars <NUM> has a rectangular cross section perpendicular to the longitudinal axis, A.

Thus, in further embodiments thereof, the first main guide rail pillar <NUM> extends through an opening <NUM> in the second mould plate <NUM>, where said opening <NUM> through the second mould plate <NUM> is formed centrally adjacent to an upper edge <NUM> of the second mould plate <NUM>, and the second main guide rail pillar <NUM> extends through another opening <NUM> in the second mould plate <NUM>, which opening is formed centrally adjacent to a lower edge <NUM> of the second mould plate <NUM>.

However, alternatively, the main guide rail system <NUM>' of the mould box <NUM> comprises a single main guide rail pillar <NUM> only, such as shown in <FIG>. In this case, preferably, the single main guide rail pillar <NUM> extends through a second opening <NUM> in the second mould plate <NUM>, which said opening <NUM> through the second mould plate <NUM> is formed centrally in the second mould plate <NUM>.

As is also apparent from the above description, the mould box <NUM> according to the invention may be utilized in an injection moulding machine as discussed above. Thus in a further aspect the invention relates to an injection moulding machine <NUM> comprising.

wherein the second mould plate <NUM> is movably arranged relative to the first mould plate <NUM>, and driven by the linear drive mechanism <NUM>.

Where, in the <FIG> embodiments the first and second mould plates <NUM>, <NUM> are rectangular or quadratic in shape, the first and seconds mould plate <NUM>, <NUM> as well as the base plate <NUM> in the <FIG> embodiment have more complex shapes. The bas plate <NUM> and the first and second mould plates <NUM>, <NUM> show openings <NUM>, <NUM>, <NUM> wherein cassettes with runner channels, mould cavities and mould cores, respectively may be inserted sideways into holders of the plates.

Claim 1:
A mould box (<NUM>) for an injection moulding machine (<NUM>), the mould box (<NUM>) comprising
- a first mould plate (<NUM>);
- a second mould plate (<NUM>) movably arranged relative to the first mould plate (<NUM>) along a longitudinal axis (A); and
- a main guide rail system (<NUM>') configured for guiding at least the second mould plate linearly away from and towards the first mould plate (<NUM>),
wherein the main guide rail system (<NUM>') comprises a main guide rail pillar (<NUM>), having a cross section perpendicular to the longitudinal axis (A),
wherein the cross-section is rectangular,
wherein the main guide rail pillar (<NUM>) extends through a third opening (<NUM>) through a bearing (<NUM>) arranged between the main guide rail pillar (<NUM>) and the second mould plate (<NUM>);
wherein a guide track (<NUM>) is formed as an elongate indention in a sidewall of the main guide rail pillar (<NUM>) and comprising a first internal guide surface (<NUM>); and
wherein a protruding bearing element (<NUM>) extends from the third opening (<NUM>) in the bearing (<NUM>) and into the guide track (<NUM>), and forming a bearing contact against the first guide surface (<NUM>) of the guide track (<NUM>).