The present invention relates to main guide rails for mold boxes for injection moulding machines used in injection moulding processes.

Background of the invention

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 arranged moveably relative to each other and guided by a set of main guide rails. 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 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. Four cylindrical main guide rail pillars are commonly arranged in parallel to each other, and intersecting the four corners of the mould plates. The linear drive mechanism drives the sliding of the at least one moveable mould plate along the set of main guide rail pillars, 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 rails, 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 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.

CN 203937071 U discloses an alignment system where a central position cylinder having a star-shaped cross section is secured to one plate and has a free end which mates with a star shaped opening in another plate. Further, two rectangular positioning bars are placed on each side of the central position cylinder.

WO 2007/063375 A1 discloses an alignment system, where one an insert block attached to a mould plate has four alignment bars arranged along each side face of the insert block, the alignment bars having free ends extending toward an insert block attached to an opposite mould plate. This other insert block has four alignment channels complementary to the alignment bars, such that insert blocks may be aligned when they are moved towards one another.

US 2014/175690 A1 and JP 2002 321222 A discloses similar alignment systems to those disclosed in CN 203937071 U and WO 2007/063375 A1.

Common to these prior art injection moulding machines, is that the alignment systems are additional to the main guide rail pillars of the clamping unit of the injection moulding machines, and that these structured take up very much space on the surfaces of the mould plates, leaving reduced space for mould cavities and mould cores, etc. Summary of the invention It is therefore an object of the invention to solve the disadvantages of the prior art systems, and to increase the variety of options. It is a further object of the invention to provide a simpler clamping unit of an injection moulding machine and a simpler mould box therefore. It is a further object of the invention to provide a clamping unit of an injection moulding machine and a mould box therefore which provides a stable movement of mould plates, thereof. It is a further object of the invention to provide a clamping unit of an injection moulding machine and a mould box therefore providing precise alignment of the mould plates thereof.

In a first aspect the objects of the invention are achieved by a clamping unit for an injection moulding machine, wherein the clamping unit comprises

- a clamping unit frame;

- a base plate fixedly arranged at a first end of the clamping unit frame;

- a second end structure fixedly arranged at a second end of the clamping unit frame; and - a mould box, wherein the mould box comprises

- a first mould plate;

- a second mould plate movably arranged relative to the first mould plate; and

- a main guide rail system configured for guiding the second mould plate linearly away from and towards the first mould plate along a longitudinal axis, wherein the main guide rail system comprises a main guide rail pillar, wherein the main guide rail pillar comprises a first end and a second end, the first end of the main guide rail pillar being fixedly connected to the base plate of the clamping unit, and the second end of the main guide rail pillar, being fixedly connected to the second end structure of the clamping unit, wherein the main guide rail pillar has a cross section perpendicular the longitudinal axis, and wherein the cross-section of the main guide rail pillar forms a polygon. It has shown that the precision of alignment of the mould plates may be improved using main guide rail pillars having polygonal cross sectional shapes, and that these can replace the traditional cylindrical main guide rail pillars of prior art main guide rail systems. It has further shown, that the using main guide rail pillars having polygonal cross sectional shapes may replace or at least reduce the need for further alignment systems.

Further, the use of polygonal main guide rail pillars allows for simpler bearing constructions, which may reduce cost and wear. Further, the use of polygonal main guide rail pillars allows for reducing the number of main guide rail pillars.

In an embodiment, the cross-sectional shape of the main guide rail pillar is generally rectangular.

In a further 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 main guide rail system comprises a first main guide rail pillar and second main guide rail pillar only, where each of the first and second main guide rail pillars has a cross section perpendicular to the longitudinal axis, and where the cross-section forms a polygon. Thus, in this embodiment the mould box and the clamping unit comprises exactly two (two and only two) main guide rail pillars. In a further embodiment thereof, 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 where 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.

Alternatively, in further embodiments, the main guide rail system comprises a single main guide rail pillar only. Thus, main guide rail system in this embodiment has on and only one main guide rail pillar. Despite the large forces acting on a mould box in use it has been discovered that a single guide rail may provide sufficient stability to support the injection moulding process. By only one main guide rail pillar with a polygonal cross sectional shape it is possible to make a guiding function with no constrains, since only one set of guide surfaces secures the position, e.g. along an axis perpendicular to the longitudinal axis. Utilizing a single main guide rail pillar only allows better access to the volume between the mould plates of the open mould box for e.g. extraction of moulded objects (e.g. via robot arms), maintenance, and for e.g. automated replacement of mould cavity/mould core cassettes. It also reduces material use and cost.

In a further embodiment, the main guide rail pillar extends through a second opening in the second mould plate and further, the second opening in the second mould plate is formed centrally in the second mould plate. Alternatively, the single main guide rail pillar extends through a second opening in the second mould plate, where said opening in the second mould plate is formed centrally adjacent to a lower edge of the second mould plate.

In a further embodiment, the main guide rail pillar may be anchored in a first opening through the first mould plate. In a further embodiment thereof, the main guide rail pillar at a first end thereof is provided with a protrusion configured for cooperating with an enlargement of the first opening in the first mould plate.

In a second aspect the objects of the invention are achieved by an injection moulding machine comprising a clamping unit according to any one of the embodiments of 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 - a frame;

- an injection unit attached to the frame;

- a clamping unit according to any one of the embodiments of the first aspect of the invention, the clamping unit being attached to the frame;; and a linear drive mechanism for moving a second mould plate of a mould box of the clamping unit.

In either case the clamping unit and/or mould box of the injection moulding machine according to the second aspect of the invention may comprise any of the features of the clamping unit and/or mould box according to any one of the embodiments of the first aspect of the invention as described above, or in the detailed description below.

A main guide rail system and any main guide rail pillars, thereof, are separate from any alignment system.

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.

Brief description of the drawings

In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

Fig. 1 schematically shows an outline of a prior art injection moulding machine;

Fig. 2, in a perspective view, shows components of a prior art mould box with two half-plates (mould plates) and a set of cylindrical main guide rail pillars;

Fig.3A, in a perspective view, shows a mould box according to one embodiment of the invention in a first position;

Fig. 3B, in a front view, shows the mould box of Fig. 3A; Fig. 3C, in a sectional side view, shows the mould box of Figs. 3A and 3B;

Fig. 4A, in a perspective view, shows the mould box of Figs. 3A-C in a second position;

Fig. 4B, in a front view, shows the mould box of Fig. 4A;

Fig. 4C, in a sectional side view, shows the mould box of Figs. 4A and 4B;

Fig. 5, in an exploded perspective view, shows the mould box of Figs. 3A-C and 4A-C;

Fig. 6, in a perspective view, shows a mould box according to another embodiment of the invention; and

Fig. 7, in a perspective view, shows a mould box according to yet another embodiment of the invention.

Detailed description of the embodiments

Fig. 1 illustrates schematically an injection moulding machine 200 as known in the art. The injection moulding machine 200 generally comprises an injection unit 210, shown in the left side of the figure, and a clamping unit 270, shown in the right side of the figure. The injection unit 210 handles injection of plastic material into a mould formed in the clamping unit 270 of the injection moulding machine 200. The injection unit 210 and the clamping unit 270 of the injection moulding machine 200 are attachable to a mount 201.

Injection moulding machines 200 generally works in the following way: Plastic granules 105 are fed into the barrel 260 of a reciprocating screw 220 of the injection unit 210 via a hopper 240. The reciprocating screw 220 is driven by a drive mechanism 230, such as an electrical motor. The plastic granules 105 fed through the hopper 240 are then transported towards the clamping unit 270 by the reciprocal screw, while being compacted and they are heated by heating devices 250 surrounding the reciprocating screw 220, until they melt and reach a suitable viscosity at a nozzle 225 at the entrance to the clamping unit 270 with the mould.

The mould is formed in a mould box 1.

The fluid plastic material is fed from the nozzle 225 through sprue channels 226 in a base plate 10 of the mould box 1, and reaches a mould cavity 21 formed in a first mould plate 20 of the mould box 1. The first mould plate 20 of the mould box 1 is connected to the base plate 10. The base plate 10 is connected to the mount 201. A second mould plate 30 which may comprise a mould core and/or further portions of a mould cavity is arranged moveably relative to the first mould plate 20, such that the mould box may be completely closed (clamped together) to allow injection of the melted plastic, and such that the mould box 1 may be opened to extracted a moulded object 100 (see Fig. 2).

In Fig. 1, the second mould plate 30 is attached to a moveable platen 290. The moveable platen 290 - and thereby the second mould plate 30 - is slideably arranged on a set of cylindrical main guide rail pillars 400. Typically, the clamping unit 270 of injection moulding machines 200 comprises four cylindrical main guide rail pillars 400 for guiding the movement of the moveable platen 290 with the second mould plate 30. The movement of the moveable platen 290 with the second mould plate 30 is performed by a linear drive mechanism 280, typically a hydraulic mechanism.

Each of the main guide rail pillars 400 of the main guide rail system of the mould box 1 of the clamping unit 270 has an elongate body, which is cylindrical, and has a first end 443 and a second end 444. The first end 443 is fixed to the base plate 10, which is fixed to a frame (not shown) of the clamping unit 270. The frame of the clamping unit 270 may form part of the frame 201 of the injection moulding machine 200, or may be fixed thereto.

The opposite end, the second end 444, of the elongate body of each main guide rail pillars 400 is fixedly connected to a second end structure 15 of the clamping unit 270. The second end structure 15 of the clamping unit 270 is fixed to the frame (not shown) of the clamping unit 270, which, as mentioned in the previous paragraph, may form part of the frame 201 of the injection moulding machine 200, or may be fixed thereto.

The second end structure 15 may also, as shown in Fig. 1, form a mount for the linear drive mechanism 280.

Now, returning to the moveable platen 290 with the second mould plate 30, this moveable platen 290 comprises through-going bearing e.g. slide bearings or ball bearings, slidably receiving the cylindrical main guide rail pillars 400.

In an injection process, the linear drive mechanism 280 clamps the first mould plate 20 and the second mould plate 30 together, whereupon plastic is injected from the reciprocal screw 220 through the nozzle 225 and into the mould cavity 21. When the plastic has filled the mould cavity 21 completely, and has cooled sufficiently for the plastic to be in solid state, then the linear drive mechanism 280 moves the second mould plate 30 away from the first mould plate 20, and the moulded object 100 is ejected from the mould cavity 21 in the first mould plate 20. The ejection of the moulded object 100 is typically done by ejector pins (not shown) formed in/through the base plate 10.

Fig. 2 shows a prior art mould box 1 for an injection moulding machine 200 (as outlined in Fig. 1), and a moulded object 100. The mould box 1 is shown in a separated state where the moulded object 100 is visible between two half plates, or mould plates 20, 30 of the mould box 1. Thus, the mould box 1 comprises two mould plates 20, 30. A first mould plate 20, here shown to comprise a mould cavity 21 of a mould, is fixedly connected to a base plate 10 of the mould box 1. The first mould plate 20 and the base plate 10 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 21 is formed as a depression in a surface of the first mould plate 20.

The first mould plate 20 is - via the base plate 10 -connected to an injection moulding machine 200, e.g. as described above. The base plate 10 may thus be connected to a mount or frame 201 , as shown in Fig. 1. A second mould plate 30 is moveably arranged relative to the first mould plate 20 and the injection moulding machine 200. The second mould plate 30 is slideably arranged on a set of main guide rail pillars 400 of a main guide rail system configured for guiding the second mould plate 30 linearly away from and towards the first mould plate 20.

The set of main guide rail pillars 400 comprises four cylindrical guide rails 400. The guide rails 400 are arranged to slide over bearings (not shown) provided through the second mould plate 30. In Fig. 2 only a portion of each main guide rail pillar400 is seen.

The main guide rail pillars 400 may fixedly secured in the openings 26 provided in the first mould plate 20. There is one opening 26 per main guide rail pillar 400.

In Fig. 2 the main guide rail pillars 400 extend through the second mould plate 30 itself, as opposed to the version shown in Fig. 1, where the second mould plate 30 is connected to a moveable platen 290, which has bearings for the main guide rail pillars 400.

In Fig. 2 the second mould plate 30 is shown with a core 31 configured for mating with the mould cavity 21 in the first mould plate 20 to form a shape corresponding to the moulded object 100. It will be appreciated that the drawings, Figs. 1-2, represent simple versions of a mould with mould plates 20, 30. Thus, in other versions, for example, the core 31 and cavity 21 may be formed in cassettes insertable or attachable into the mould plates 20, 30 or to insert blocks attached to the mould plates. It will also be appreciated that the mould plates may comprise plurality of cooperating cores and cavities. It will further be appreciated that some or all the cores and the cavities may be reversed between the mould plates. It will also be appreciated that the first mould plate 20 may not be fixed to the base plate 10, but may be movable relative thereto. It will further be appreciated that mould boxes may comprise further mould plates. These considerations apply to prior art mould boxes, as well as to the mould boxes and clamping units according to the various embodiments of the invention described below.

Figs. 3-7 show embodiments of a mould box 1 for a clamping unit 270 for an injection moulding machine 200, according to the invention.

The mould box 1 may be used with a clamping unit 270 for an injection moulding machine 200 as described above, the mould box 1, the clamping unit 270, and the injection moulding machine 200, differing in the arrangement of the main guide rail system 40’.

The mould box 1 comprises a base plate 10 and a first mould plate 20 connected thereto. During use in injection moulding processes, the first mould plate 20 is fixed in position relative to the base plate 10. The base plate 10 is fixedly connectable (immovable) to a frame of the clamping unit 270, which - as also mentioned above may be a frame 201 of the injection moulding machine 200, form part of the frame of the injection moulding machine 200 or be immovably connected to the frame 201 of the injection moulding machine 200, such as the injection moulding machine, e.g. as described in connection with the prior art injection moulding machine 200 shown in Fig. 1. The first mould plate 20 may comprise one or more mould cavities (not shown) formed as depressions in a first surface 22 of the first mould plate 20. An opposite side, second side 23 of the first mould plate 20 faces the base plate 10, see e.g. Fig. 5.

The first mould plate 20 may be formed integrally with the base plate 10, or it may - as shown in Figs. 3-5 - be formed as individual/separate parts and subsequently be joined/connected, such that the first mould plate 20 is fixed to the base plate 10 at least during the injection moulding process. The first mould plate 20 may be connected to the base plate 10 using for example bolts.

The not shown one or more mould cavities 21 may - in also not shown - further embodiments be formed in one or more cassettes attachable on - or insertable in suitable recesses in - the first surface 22 of the first mould plate 20, such as insertable in mould blocks (not shown) formed on and extending from the first side 22 of the first mould plate 20. Such mould blocks are shown in e.g. WO 2007/063375 A1.

Further, the first mould plate 20 and/or the base plate 10 may be equipped with sprue channels and runner channels necessary to connect the one or more mould cavities in the first mould plate 20 with an injection nozzle 225 of an injection moulding machine 200, such as an injection moulding machine as shown in Fig. 1. Such sprue channels and runner channels are not shown in Figs. 3-7.

The mould box 1 according to the invention - and as shown in Figs. 3-5 - further comprises a second mould plate 30.

The second mould plate 30 is movably arranged relative to the first mould plate 20. Thereby, the second mould plate 30 is also movably arranged relative to the base plate 10.

The mould box 1 according to the invention - and as shown in Figs. 3-5 - further comprises a main guide rail system 40’ configured for guiding the second mould plate linearly away from and towards the first mould plate 20.

The main guide rail system 40’ allows at least the second mould plate 30 to be movably arranged relative to the base plate 10. The second mould plate 30 is movable on the main guide rail system 40’ by a linear drive mechanism 280 as shown in Fig. 1. Such a linear drive mechanism 280 is most commonly hydraulic or electrical.

In other not shown embodiments, the first mould plate 20 may also be movably arranged, relative to the base plate 10, the clamping unit 270 of the injection moulding machine 200 further comprising means for moving the first base plate 20 on the main guide rail system 40’.

In yet other - not shown - embodiments, the mould box 1may comprise a third plate, or even further plates(not shown) arranged between the first and second mould plates 20, 30, where for example runner channels are arranged in third plate. Such a third plate may be fixed relative to the base plate 10 or it may be moveable on the main guide rail system 40’ in order to facilitate de-shaping of the runner channels.

As shown in Figs. 3-5, the main guide rail system 40’ comprises a single main guide rail pillar 40, only. That means on and only one main guide rail pillar 40. In principle, the main guide rail system may 40’ may comprise more than a single main guide rail pillar, but only one is needed. Fig. 7 illustrates an embodiment, where the mould box comprises two main guide rail pillars, a first main guide rail pillar 40 and a second main guide pillar 40. The first main guide rail pillar 40 extends through an opening 130 formed through the second mould plate 30. This opening 130 through the second mould plate 30 is formed adjacent to an upper edge 34 of the second mould plate 30, and centrally along this edge 34. Further, the second main guide rail pillar 40 extends through another opening 130 in the second mould plate 30. This is formed adjacent to a lower edge 35 of the second mould plate 30, and centrally along this edge 35.

The main guide rail pillar 40 is elongate, having a first end 43 and second end 44, an elongate body part 41 extending between the first end 43 and the second end 44, and a longitudinal axis A. The main guide rail pillar 40 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 2-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 main guide pillar according to the invention may have any polygonal shape. However, as shown in Figs. 3-7, the polygonal shape may in some embodiments be rectangular.

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 40 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 40 having a cross-section/cross-sectional shape forming a polygon will result in the main guide rail pillar 40 having a set of planar guide surfaces 45’, 45”, 46’, 46” for cooperating with a bearing element 50 arranged on the second mould plate 30. The number of planar guide surfaces on the main guide rail pillar 40 will depend on the number of sides of the polygonal cross- section/cross-sectional shape of the main guide rail pillar 40. The main guide rail pillar 40 shown in Figs. 3-5 having a rectangular cross section has two wider planar guide surfaces 45’, 45”, and two narrower planar guide surfaces 46’, 46”. The two wider planar guide surfaces 45’, 45” are parallel to each other and formed on opposed sides of the main guide rail pillar 40. Similarly, the two narrower planar guide surfaces 46’, 46” are parallel to each other and formed on opposed sides of the main guide rail pillar 40, but perpendicular to the two wider planar guide surfaces 45’, 45”.

The second mould plate 30 may comprise one or more mould cores (not shown) extending outward from a first surface 32 of the second mould plate 20, facing the first surface of the first mould plate 20. An opposite side, second surface 33 of the second mould plate 320 faces away from the first mould plate 20 and the base plate 10, see e.g. Fig. 5. The second mould plate 30 is arranged moveably relative to the first mould plate 20, such that the mould box may be completely closed (clamped together) to allow injection of the melted plastic, and such that the mould box 1 may be opened to extracted a moulded object, e.g. similar to the moulded object 100 shown in Fig. 2.

The one or more (not shown) mould cores 31 may - in also not shown - further embodiments be formed in one or more cassettes attachable on - or insertable in suitable recesses in - the first surface 32 of the second mould plate 30, such as insertable in mould blocks (not shown) formed on and extending from the first side 32 of the second mould plate 30. Such mould blocks are shown in e.g. WO 2007/063375 A1.

As is the case with the first mould plate 20, described above, the one or more mould cores 31 (not shown in Figs. 3-7)(and/or further portions of mould cavities) may - in also not shown - further embodiments be formed in one or more cassettes, which cassettes are attachable on - or insertable in suitable recesses in - the first surface 32 of the second mould plate 30.

As is the case with the prior art examples described above, the mould box 1 according to the invention may form part of a clamping part 270 of an injection moulding machine 200, in this case however with a single polygonal cross-section main guide rail pillar 40 (instead of the four cylindrical main guide rails 400, shown in Fig. 1) for guiding the movement of the second mould plate 30. The movement of the second mould plate 30 is performed by a linear drive mechanism 280, for example a hydraulic mechanism.

As shown in Figs. 3-5 and 6, the main guide rail pillar 40 extends through a second opening 130 in the second mould plate 30. The first opening 130 in the second mould plate 30 is a through-going opening extending all the way through the second mould plate 30.

The second opening 130 in the second mould plate 30 preferably has a cross sectional shape corresponding to the cross-sectional shape of the main guide pillar 40 such that the main guide rail pillar 40 may be slidably arranged therein.

Preferably, the second opening 130 in second mould plate 30 is provided with a bearing element 50, such as to provide a slide bearing between the second mould plate 30 and the main guide rail pillar. In this case the second opening 130 in the second mould plate 30 is configured to receive the bearing element 50. The bearing comprises a bearing element 51 with inner surfaces configured for contacting the planar surfaces of the main guide rail pillar 40. The bearing element 50 may, as shown in Fig. 5, have a main body part 51 and flange 52, which flange has a larger cross sectional extent than that of the main body part 51. In such cases the second opening 130 in the second mould plate 30 may comprise one first section 131 configured for receiving the main body part 51 of the bearing element 50, and another, second section 132 with a larger cross-sectional extend than the first section 131, and configured for receiving the flange 52 of the bearing element 50, see e.g. Fig. 4C.

As shown in Figs. 3-5 and 6, the main guide rail pillar 40 extends through an opening formed through the bearing element 50, a third opening 150. The third opening 150 in the bearing element 50 is a through-going opening extending all the way through the bearing 50. The third opening 150, i.e. the opening through the bearing 50 preferably has a cross sectional shape corresponding to the cross- sectional shape of the main guide pillar 40 such that the main guide pillar 40 may be may be slidably arranged therein.

As shown in Figs. 3-5 and 6, the main guide rail pillar 40 also may extend through a first opening 120 in the first mould plate 20. The first opening 120 in the first mould plate 20 is a through-going opening extending all the way through the first mould plate 20. The first opening 120 in the first mould plate 20 preferably has a cross sectional shape corresponding to the cross-sectional shape of the main guide pillar 40 such that the main guide pillar 40 may be received and fixedly anchored.

The main guide rail pillar 40 may have a main body part 41 and flange or protrusion 42 having a larger cross sectional extent than that of the main body part 41 , see e.g. Fig.5. In such cases, and as shown in e.g. Fig 4C, the first opening 120 in the first mould plate 20 may comprise one first section 121 configured for receiving the main body part 41 of the main guide rail pillar 40, and another, second section 122 with a larger cross-sectional extend than the first section 121, and configured for receiving the flange 42 of the main guide rail pillar 40, see e.g. Fig. 4C. 6. The main guide rail pillar, 40 at a first end 43 thereof, may thereby be provided with a protrusion 41 configured for cooperating with an enlargement 121 of the second opening 120 in the first mould plate 20.

Thus, the main guide rail pillar 40 is anchored in first opening 120, i.e. the opening formed through the first mould plate 20.

In either case, and as shown in Figs. 3-5 the second opening 130 in the second mould plate 30 is formed centrally in the second mould plate 30. In this case, it follows that the first opening 130 in the first mould plate 30 is also formed centrally in the second mould plate 30.

In other embodiments, and as illustrated in Fig. 6, a single main guide rail pillar may not necessarily have to be arranged through a centrally located opening 130. Fig. 6 shows an embodiment, where a single main guide rail pillar 40 is arranged through an opening 130 (with a bearing element 50, e.g. as mentioned above), which is located adjacent to a lower edge 35 of the second mould plate 30, and centrally on the lower edge 35.

The one or more mould cavities 21 may be formed around the first opening 130 in the first mould plate 20. Further, mating mould cores 31 may be formed around the second opening in the movable, second mould plate 30.

Figs.3A-C, in various views, show a mould box 1 according to one embodiment of the invention, in a first position or stage, where the first and second mould plates 20, 30 are in close contact and clamped together. This illustrates a position, where melted plastic may be injected into the (not shown) mould cavity formed between the first and second mould plates 20, 30. Correspondingly, figs. 4A-C show the mould box of Figs. 3A-C in a second position, where the first and second mould plates 20, 30 are separated from each other. This illustrates a position, where moulded objects 100 may be removed from the mould cavity.

It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description.

Parts list

1 mould box

10 base plate 15 second end structure of the clamping part/clamping unit

20 first mould plate

21 mould cavity

24 upper edge of the second mould plate

25 lower edge of the second mould plate 22 first surface of the first mould plate

23 second side of the first mould plate, opposite to first side

24 upper edge of the first mould plate

25 lower edge of the first mould plate

26 openings provided in the first mould plate (prior art) 30 second mould plate

31 mould core

32 first surface of the second mould plate

33 second side of the second mould plate, opposite to first side

34 upper edge of the second mould plate 35 lower edge of the second mould plate

40’ main guide rail system

40 main guide rail pillar, first main guide rail pillar, second main guide rail pillar

41 elongate body part of the main guide rail pillar

42 protrusion at end of the elongate body part of the main guide rail pillar 43 first end of the elongate body part of the main guide rail pillar

44 second end of the elongate body part of the main guide rail pillar

45’ surface of main guide rail pillar

45” surface of main guide rail pillar

46’ surface of main guide rail pillar 46” surface of main guide rail pillar

50 bearing/bearing element

51 bearing element

51 main body part of the bearing element

52 flange of the bearing element 100 moulded object 105 plastic granules 120 opening through the first mould plate, first opening 121 enlargement of the first opening, i.e. 130 opening formed through the second mould plate, second opening

131 first section of the second opening, the opening formed through the second mould plate

132 second section of the second opening, the opening formed through the second mould plate 150 opening through bearing element, third opening

200 injection moulding machine 201 frame/mount of the injection moulding machine 210 injection part/injection unit 220 reciprocating screw arrange in barrel of injection part of injection moulding machine

225 nozzle for injecting melted plastic into the mould box

226 sprue channels 226 in a base plate 230 drive mechanism for reciprocating screw, such as an electrical motor 240 hopper, for feeding plastic granules in barrel of injection part of injection moulding machine

260 barrel 250 heating devices 270 clamping part/clamping unit 280 linear drive mechanism 290 moveable platen

400 cylindrical main guide rails

A longitudinal axis of main guide rail pillar