DE102022129292A1 - Injection unit for a molding machine and method using such an injection unit - Google Patents

Abstract

Injection unit for a molding machine (2), comprising- an injection cylinder (3) which extends along a longitudinal axis and- an injection piston (5) arranged to be linearly displaceable in the injection cylinder (3) along the longitudinal axis (4), the injection cylinder (3) has at least one clearance (6) which has a width (18) greater than/equal to a diameter of the injection piston (5), and that the injection piston (5) is in a retracted position relative to the at least one clearance (6) axially such that the injection plunger (5) can be guided through the at least one opening (6).

Description

The present invention relates to an injection unit for a molding machine having the features of the preamble of claim 1, a molding machine with such an injection unit, and a method using an injection unit.

Molding machines can be understood to mean injection molding machines, transfer presses, presses and the like. Forming machines in which the plasticized mass is fed to an open mold are also entirely conceivable.

In the following, the state of the art will be outlined using an injection molding machine. The same applies in general to shaping machines.

• - einen Einspritzzylinder, welcher sich entlang einer Längsachse erstreckt, und
• - einen im Einspritzzylinder entlang der Längsachse linear verschiebbar angeordneten Einspritzkolben.

Generic injection units for an injection molding machine include:

• - an injection cylinder extending along a longitudinal axis, and
• - an injection piston arranged linearly displaceable in the injection cylinder along the longitudinal axis.

In some applications, injection unit solutions known from the prior art have an injection cylinder which can be placed against a mold at a nozzle-side end of the injection cylinder.

At an end opposite the injection cylinder, there is usually a piston-side end of the injection cylinder, via which an injection piston can be inserted into the injection cylinder and is usually linearly displaceable via a piston rod in the injection cylinder.

During the production process of the injection molding machine, the injection piston is moved to a retracted position in the injection cylinder. During this retraction movement or when the retracted position is reached, a plasticized plastic mass is supplied to the injection cylinder—more precisely: to the area released in the injection cylinder.

When a desired volume of plasticized plastic mass has been fed to the injection cylinder, the injection piston in the injection cylinder is moved linearly in the direction of the nozzle-side end of the injection cylinder, as a result of which the plasticized plastic mass is pushed out of the injection cylinder and injected into a mold resting against the nozzle-side end of the injection cylinder.

This process can now be repeated in cycles, as a result of which a plasticized plastic mass can be fed cyclically to a mold and hardens in the mold, as a result of which injection-molded workpieces can be produced.

In order to service the injection plunger, it is necessary to pass the injection plunger out through the rod end of the injection cylinder so that the injection plunger is free for maintenance, service and/or assembly/disassembly.

This measure is regularly required to check or replace wear on the injection piston or to replace, maintain and/or monitor wearing parts on the injection piston, such as scrapers.

As can be imagined, this assembly/disassembly of the injection piston takes up a great deal of work and space, since the injection piston with the piston rod has to be guided linearly out of the injection cylinder, which massively increases the space required along a longitudinal axis of the injection cylinder.

Another disadvantage is that in most cases components of the injection unit must first be dismantled in order to enable the injection piston to be extended from the injection cylinder, with surrounding components of the injection unit (e.g. usually also the plasticizing unit) having to be dismantled in order to release them accordingly allow the injection piston, which makes the maintenance, service and / or assembly / disassembly work massively difficult.

The object of the present invention is therefore to at least partially improve the above-mentioned disadvantages of the prior art and/or to provide an injection unit which requires less maintenance, service and/or assembly/disassembly.

This object is achieved according to the invention by an injection unit for a molding machine having the features of claim 1, a molding machine having such an injection unit and a method using an injection unit having the features of claim 16.

• - einen Einspritzzylinder, welcher sich entlang einer Längsachse erstreckt und
• - einen im Einspritzzylinder entlang der Längsachse linear verschiebbar angeordneten Einspritzkolben

wobei der Einspritzzylinder wenigstens eine Freistellung aufweist, welcher eine Breite größer/gleich einem Durchmesser des Einspritzkolbens aufweist und wobei der Einspritzkolben in einer zurückgezogenen Stellung relativ zur wenigstens einen Freistellung axial so liegt, dass der Einspritzkolben durch die wenigstens eine Freistellung führbar ist.According to the invention, an injection unit for a molding machine comprises:

• - an injection cylinder extending along a longitudinal axis and
• - an injection piston arranged linearly displaceable in the injection cylinder along the longitudinal axis

wherein the injection cylinder has at least one clearance which has a width greater than/equal to a diameter of the injection plunger and wherein the injection plunger is in a retracted position relative to the at least one clearance axially such that the injection plunger can be guided through the at least one clearance.

A clearance on an injection cylinder makes it possible for the injection piston to be guided out of or into the injection cylinder, with it not being necessary to guide it out via an end of the plasticizing cylinder on the piston rod side.

This results in the essential advantage that the linear drive unit of the injection piston no longer has to be put into a state in which the injection piston leaves the injection cylinder at an end on the piston rod side, but the possibility is created that the injection piston can already be moved beforehand (in a not so far retracted state by the linear drive unit) is introduced via the at least one exemption in the injection cylinder or discharged from it. According to the invention, the injection plunger can therefore be changed or serviced particularly easily and quickly.

This enables a much more compact design of the injection unit, especially with regard to a longitudinal axis. It is no longer necessary to be able to put the injection unit in a state in which the injection piston leaves the injection cylinder along the longitudinal axis for assembly/disassembly, service or maintenance work.

The at least one clearance thus makes it possible in a simple manner to move the injection piston out of or into the injection cylinder, although it may also be sufficient for service or maintenance work to release the injection piston via the at least one clearance, so that With at least one exemption, qualified personnel can check and appraise the injection piston or carry out minor maintenance work.

For the purposes of the present document, an exemption can also be in the form of an opening or recess in the injection cylinder and/or a supporting structure.

The injection cylinder and/or the support structure can preferably be made in one piece but also in several pieces.

In certain embodiments, the exemption can be realized by a shortened injection cylinder. A guide for the injection piston and/or the piston rod and/or struts for force transmission between the injection cylinder and the injection piston (preferably using a clamping plate that can be moved relative to the injection cylinder and on which the injection piston is supported) can be provided.

The width of the at least one clearance can preferably extend transversely to the longitudinal extent of the injection cylinder.

The injection piston can be regarded as a component comprising a piston tip which has a surface which comes into contact with the plasticized material to be expelled.

Molding machines can be understood to mean injection molding machines, transfer presses, presses and the like. Forming machines in which the plasticized mass is fed to an open mold are also entirely conceivable.

A device and/or method according to the invention can be used in already known design variants of the prior art, as described for example in the introduction to the description, and can be installed subsequently.

Advantageous embodiments of the invention are defined in the dependent claims.

Provision can preferably be made for the injection cylinder to have a lateral surface having an inner diameter, with the at least one clearance being designed as an opening in the injection cylinder that passes through the lateral surface.

At least one clearance, which penetrates the lateral surface in a diameter of the injection cylinder on one side, whereby the interior of the injection cylinder is exposed through the opening, can be regarded as a penetrating opening, but also as an opening completely penetrating the injection cylinder, which extends the lateral surface of the injection cylinder in a projecting Seen level completely interspersed, so that two openings on the lateral surface release the interior of the injection cylinder to the environment.

Provision can preferably be made for a piston rod which is connected in a movement-locked manner to the injection piston and is designed to linearly displace the injection piston.

To move the piston rod, a linear drive unit can be provided, which can be implemented, for example, by a particularly preferably hydraulic piston-cylinder unit.

It can be provided that the injection piston is or can be connected to the piston rod by means of a positive connection, preferably a groove connection, particularly preferably a groove connection having a T-groove.

Advantageously, it can be provided that the injection piston can be quickly connected or released with the piston rod via the form-fitting connection, whereby a form-fitting connection can be established or released simply by a relative movement between the injection piston and piston rod, without the connection having to be made by means of additional fastening means (e.g screws) would have to be loosened or tightened.

Provision can preferably be made for the injection cylinder to have an end on the piston rod side and an end on the injection nozzle side along the longitudinal axis, the at least one clearance being spaced apart from at least one of the two ends—preferably both ends.

Provision can be made for the injection cylinder to have an injection nozzle at an injection-nozzle-side end, which injection nozzle can be placed on a molding tool of the molding machine.

Provision can preferably be made for the injection cylinder to be exposed to the environment at the end on the piston rod side with an inner diameter of the injection cylinder and/or the lateral surface, with a piston rod engaging in the injection cylinder on the end of the injection cylinder on the piston rod side in order, particularly preferably, to close the injection piston linearly in the injection cylinder postpone.

Provision can be made for the at least one clearance to be at a distance of at least 0.1%, preferably 10%, particularly preferably 20% of a total length of the injection cylinder along the longitudinal extension from the end of the injection cylinder on the piston rod side.

Provision can preferably be made for the at least one clearance to have a length along the longitudinal axis that is greater than or equal to a longitudinal extent of the injection piston along the longitudinal axis.

It can be provided that the injection cylinder has at least one further clearance, which is preferably arranged on the injection cylinder opposite the at least one clearance, particularly preferably represents a clearance of the at least one clearance mirrored about the center line of the injection cylinder.

Another disadvantage of known embodiments of the prior art is that, of course, a 100% seal between the injection cylinder and the injection plunger cannot be guaranteed, which means that plasticized plastic can escape through a gap (usually a very small gap) from the side of the injection cylinder that faces the nozzle-side end of the injection cylinder Injection piston reaches the piston-side end facing side of the injection piston.

This leakage of plasticized plastic mass is discharged via an end of the injection cylinder on the piston rod side in order to be able to ensure continued smooth operation of the injection unit.

However, since the path between the injection piston and the end of the injection cylinder on the piston rod side is very long, the plasticized plastic mass often cools down and thus hardens before it can be discharged from the injection cylinder and thus the injection unit.

However, this removal of the solidified or hardened leakage also represents an increased effort, with hardened plastic mostly having to be mechanically removed during maintenance work.

The provision of the at least one further clearance creates the possibility that the leakage can be discharged via the at least one further clearance, so that the leakage is discharged in a plasticized or plastic state after a short distance from the leakage point to the at least one further clearance can be before it solidifies and possibly attaches itself to the injection piston and / or the injection cylinder.

The centerline of the injection cylinder may correspond to the longitudinal axis of the injection cylinder, if desired. However, it can also be provided that the longitudinal axis represents an axis parallel to the center line, with the center line as the center of the injection cylinder along the longitudinal axis.

Provision can preferably be made for the at least one clearance to be arranged on the injection cylinder on an upper side and preferably for the at least one further clearance to be arranged on an opposite underside.

The upper side of the injection cylinder is to be understood as the vertical, upper end or vertically upper area of the lateral surface of the injection cylinder in a section transverse to the longitudinal extent (in a position of use) of the injection cylinder.

By arranging the at least one further opening on an underside of the injection cylinder, leakage (e.g. plasticized plastic mass) can be discharged downwards via the at least one further opening using the force of gravity and, for example, be fed to a collection container arranged under the at least one further opening.

Particularly preferably, the at least one cutout and the at least one further cutout can be designed as an opening that continuously penetrates the plasticizing cylinder.

At least one wiper ring can be provided on the injection cylinder in the at least one free space, preferably on a side facing an injection-nozzle-side end of the injection cylinder.

A further wiper ring can preferably be arranged on a side of the at least one free space on the injection cylinder that faces a piston rod-side end of the injection cylinder.

Particularly preferably, it can be provided that the at least one and/or the at least one further scraper ring is designed in two parts.

Two-part wiper rings can be designed, for example, in the shape of a half shell, so that they can enclose an injection piston and/or a piston rod by appropriate assembly without the injection piston and/or the piston rod having to be moved out of the wiper ring by linear displacement.

• - wenigstens zweiteilig ausgebildet ist, wobei vorzugsweise eine Teilung des Abstreifrings entlang einer die Längsachse enthaltenden - vorzugsweise horizontalen - Ebene vorgesehen ist und/oder
• - eine erste Temperiervorrichtung, vorzugsweise eine Heizvorrichtung, aufweist, welche erste Temperiervorrichtung dazu ausgebildet ist, den wenigstens einen Abstreifring und/oder den wenigstens einen weiteren Abstreifring auf eine vorgebbare Temperatur, besonders bevorzugt einer Temperatur der plastifizierten Kunststoffmasse, zu bringen oder halten und/oder
• - mit einer Abstreifkante zumindest bereichsweise die Kolbenstange umschließt.

It can preferably be provided that the at least one scraper ring and/or the at least one further scraper ring

• - Is formed at least in two parts, preferably a division of the wiper ring along a longitudinal axis containing the - preferably horizontal - plane is provided and / or
• - has a first temperature control device, preferably a heating device, which first temperature control device is designed to bring or maintain the at least one scraper ring and/or the at least one further scraper ring to a predeterminable temperature, particularly preferably a temperature of the plasticized plastic mass, and/or
• - At least partially encloses the piston rod with a scraping edge.

Provision can be made for the injection piston to have a second temperature control device, which second temperature control device is designed to temperature control the injection piston to a predeterminable temperature.

For example, a gap dimension between the injection piston and the injection cylinder can be influenced via the thermal expansion of the injection piston relative to the injection cylinder in order to minimize leakage between the injection piston and the injection cylinder. This thermal expansion can be controlled or regulated by the definable temperature of the second temperature control device.

It could be provided, for example, that a gap size between the injection cylinder and the injection piston is measured and that the gap size is minimized by targeted adjustment of the temperature of the injection piston (and thus a targeted influence on thermal expansion of the injection piston), which also minimizes the leakage across this gap size can be.

It can be provided that the injection cylinder has a feed opening, preferably on a lateral surface of the injection cylinder, which is arranged such that a plasticized plastic mass can be fed via the feed opening to an injection volume formed by the injection piston and the injection cylinder.

The at least one feed opening is preferably connected or can be connected to a plasticizing unit, it being possible for the plasticizing unit to have a plasticizing screw and/or a plasticizing extruder.

In the case of plasticizing screws or plasticizing extruders, the material to be plasticized is plasticized by shearing, which is exerted on the material to be plasticized by the rotation of the screw(s), and optionally by the action of heat. Plasticizing screws are in contrast to Plasticizing extruders can also be moved axially relative to the plasticizing cylinder in order to be able to implement a piston function.

An injection nozzle can preferably be provided at an injection-nozzle-side end of the injection cylinder, a plasticized plastic material being able to be pushed out of the injection cylinder via the injection nozzle via a linear displacement of the injection piston relative to the injection cylinder.

It can preferably be provided that the injection nozzle can be placed against a mold, particularly preferably an injection molding machine, and the plasticized plastic compound can be injected into the mold via the injection nozzle.

Furthermore, protection is sought for a shaping machine, in particular an injection molding machine, with at least one injection unit according to the invention.

• - einen Einspritzzylinder, welcher sich entlang einer Längserstreckung erstreckt und
• - einen im Einspritzzylinder entlang der Längsachse linear verschiebbar angeordneten Einspritzkolben,

wobei der Einspritzkolben und/oder eine Kolbenstange in einem ersten Schritt linear in eine zurückgezogene Stellung relativ zum Einspritzzylinder verschoben wird und in einem zweiten Verfahrensschritt der Einspritzkolben radial durch wenigstens eine Freistellung des Einspritzzylinders, welche wenigstens eine Freistellung eine Breite größer/gleich einem Durchmesser des Einspritzkolbens aufweist, geführt wird.Protection is also sought for a method using an injection unit comprising

• - an injection cylinder, which extends along a longitudinal extension and
• - an injection piston arranged linearly displaceable in the injection cylinder along the longitudinal axis,

the injection piston and/or a piston rod being displaced linearly in a first step into a retracted position relative to the injection cylinder and in a second method step the injection piston being displaced radially through at least one clearance of the injection cylinder, which at least one clearance has a width greater than/equal to a diameter of the injection piston has, is guided.

That is, according to the method of the present invention, the injection plunger can be taken out of the injection cylinder after the injection plunger is shifted to the retracted position (removing the injection plunger), and the injection plunger can be placed in the injection cylinder after the piston rod is shifted to the retracted position ( installing the injection plunger).

• 1 ein erstes Ausführungsbeispiel einer Einspritzeinheit,
• 2 eine Ansicht von oben auf das Ausführungsbeispiel der 1,
• 3 eine Detailansicht des Details A aus 1,
• 4, 5 das Detail A aus 1 und 3 in verschiedenen Betriebszuständen,
• 6 bis 8 ein weiteres Ausführungsbeispiel einer Einspritzeinheit,
• 9, 10 eine perspektivische Ansicht des Ausführungsbeispiels aus den 6 bis 8,
• 11 bis 18 ein weiteres Ausführungsbeispiel einer Einspritzeinheit und
• 19 eine Formgebungsmaschine mit einer Einspritzeinheit.

Further advantages and details of the invention result from the figures and the associated description of the figures. It shows:

• 1 a first embodiment of an injection unit,
• 2 a top view of the embodiment of FIG 1 ,
• 3 a detailed view of detail A 1 ,
• 4 , 5 the detail A out 1 and 3 in different operating states,
• 6 until 8th another embodiment of an injection unit,
• 9 , 10 a perspective view of the embodiment of the 6 until 8th ,
• 11 until 18 another embodiment of an injection unit and
• 19 a molding machine with an injection unit.

1 shows a first embodiment of an injection unit 1, wherein the 1 shows a side view of this embodiment and 2 a top view of the embodiment of an injection unit 1 .

The representations shown of the embodiment of 1 and 2 also differ in that 1 represents a state of the injection unit 1 loaded with a plasticized plastic mass and 2 represents an extended state of the injection unit 1.

The embodiment of the injection unit 1 of 1 has an injection cylinder 3 which extends along a longitudinal axis 4 .

An injection piston 5 is arranged in the injection cylinder 3 so that it can be displaced linearly along the longitudinal axis 4 .

This injection piston 5 is positively connected to the piston rod 9 and can be displaced linearly in the plasticizing cylinder 3 along the longitudinal axis 4 via the linear drive units 21 .

The linear drive units 21 of the piston rod 9 for the linear movement of the injection piston 5 of this exemplary embodiment are implemented by hydraulically operated piston-cylinder units.

The injection cylinder 3 of this exemplary embodiment has an injection nozzle 17 on the nozzle-side end of the injection cylinder 3, via which a plasticized plastic mass can be pushed out of the interior of the injection cylinder 3 via a linear movement of the injection piston 5 and can be fed to a mold 32 of a molding machine 2, or more precisely said: can be injected into the mold 32.

The injection nozzle 17 is connected to the injection cylinder 3 via the flange 37 , the flange 37 representing an extension of the injection cylinder 3 and having the feed opening 16 .

The plasticized plastic mass can be fed to the injection cylinder 3 via the feed opening 16 .

In this exemplary embodiment, the injection cylinder 3 is connected to the machine frame 24 via the clamp 39 . The clearance 6 of the injection cylinder 3 is arranged on a side of the clamping 39 facing towards the injection nozzle 17 .

This plasticized plastic mass is created by plasticizing a plastic with the aid of the plasticizing unit 20, with a plastic to be plasticized being fed to the plasticizing unit 20 via the hopper 25 (usually in the form of plastic granules).

The plasticizing unit 20 plasticizes the plastic to be plasticized into a plasticized plastic mass and forwards the plasticized plastic mass via the feed device 26 and the feed opening 16 to the injection unit 1 - more precisely: the injection cylinder 3.

The plasticizing unit 20 can be formed by a plasticizing screw or a plasticizing extruder, with the plastic to be plasticized being plasticized by means of rotation of the extruder or the screw by means of shearing heat.

The plasticizing unit 20 is driven via the drive unit 23.

In order to additionally support the plasticization of the plasticized plastic, the plasticizing unit 20 has heating strips 19 arranged on the circumference, which are designed to transfer additional heat energy to the plasticizing unit 20 and to support the plasticizing of the plastic to be plasticized.

Also on the circumference - to be more precise: the lateral surface 7 - of the injection cylinder 3 are heating strips 19 which are designed to emit thermal energy to the injection cylinder 3 and the injection unit 1, it being possible to ensure that the plasticized plastic mass present in the injection unit 1 a desired temperature can be maintained and no hardening of the plasticized plastic mass in the injection unit 1 takes place.

During one cycle of the injection unit 1, the injection piston 5 is moved into a retracted injection position via the piston rod 9 and the drive unit 21 (as in 1 shown).

During the retraction of the injection plunger 5 in the injection cylinder 3 , plasticized plastic mass is fed into the injection cylinder 3 by the plasticizing unit 20 via the feed device 26 and the feed opening 16 .

This supply of plasticized plastic mass from the plasticizing unit 20 into the plasticizing cylinder 3 is carried out until a desired mass of plasticized plastic has accumulated between the nozzle-side end of the plasticizing cylinder 3 and the injection plunger 5 .

When this desired mass of plasticized plastic mass is reached, the supply is stopped and the injection piston 5 is initiated via a linear movement of the piston rod 9 in the direction of the nozzle-side end of the plasticizing cylinder 3, until an extended position (see 2 ) is achieved, wherein the previously supplied plasticized plastic mass from the plasticizing unit 20 was completely fed via the injection nozzle 17 to a molding tool 32 of a molding machine 2 during the linear movement.

The injection piston 5 is then again moved back linearly in the direction of the end of the injection cylinder 3 on the piston rod side (injection position), again plasticized mass is fed from the plasticizing unit 20 to the injection cylinder 3 and a new cycle is thus started.

The injection cylinder 3 also has a clearance 6, which has a width 18 greater than/equal to a diameter of the injection plunger 5 (see detail A, which is shown in 3 shown enlarged).

The clearance 6 of this embodiment has a width of 18 (compare 5 ), which is formed larger than a diameter of the injection piston 5.

Furthermore, the clearance 6 has a length 11 , which length 11 along the longitudinal axis 4 is greater than the longitudinal extension of the injection piston 5 along the longitudinal axis 4 .

The longitudinal axis 4 of the injection unit 1 of the exemplary embodiment is shown overlapping the center line 13 of the injection cylinder 3 .

Furthermore, the injection cylinder 3 has a further exemption 12, which through the same chen dimensions in width 18 and length 11 as the exemption 6 is formed.

The further clearance 12 is arranged on the injection cylinder 3 opposite the clearance 6 - to be more precise, the further clearance 12 represents a clearance of the clearance 6 mirrored about the central axis 13 of the injection cylinder 3.

The clearance 6 is arranged on an upper side of the injection cylinder 3 and the further clearance 12 on an underside of the injection cylinder 3 opposite the upper side.

The clearance 6 and the further clearance 12 of this exemplary embodiment are, strictly speaking, designed as an opening penetrating the injection cylinder 3, two openings (clearance 6 and further clearance 12) of the interior of the injection cylinder 3 being formed by penetrating through the center line 13 of the injection cylinder 3.

Thus, the exemption 6 for assembly and maintenance work on the injection piston 5 (as later by the 4 and 5 explained) can be used, whereas the further exemption 12 can also be used to remove leakage of plasticized plastic mass between the injection piston 5 and the injection cylinder 3 from the side of the injection piston 5 on the piston rod side.

In order to discharge such a leakage from the injection cylinder 3, the scraper rings 14, 15 are provided.

The scraper ring 14 is arranged on an injection nozzle-side end of the clearance 6 and encloses the piston rod 9.

Due to the formation of a scraping edge of the scraper ring 14, plasticized plastic mass residues which leak onto the piston rod 9 are scraped off the piston rod 9 and discharged via the further opening 12 into a collection container 22 with the aid of gravity.

At the end of the clearance 6 on the piston rod side, another scraper ring 15 is provided, which is also designed with a scraper edge which encloses the piston rod 9 and removes further contaminants on the piston rod 9 due to leakage of plasticized plastic mass.

The scraper rings of this embodiment are designed in two parts, with a horizontal division of the scraper rings 14, 15 being provided.

A corresponding two-part design makes it possible to dismantle the scraper rings 14, 15 and lift them off the piston rod 9 without the piston rod 9 having to be passed through the scraper rings 14, 15 in order to release them.

The scraper rings 14, 15 are particularly preferably designed in the form of half shells.

Furthermore, the scraper rings 14, 15 have a first temperature control device - more precisely: a heating device - whereby the scraper rings 14, 15 can be brought to a desired temperature (a temperature of the plasticized plastic mass) via the heating device in order to prevent the plasticized plastic mass from sticking to prevent hardening.

The clearances 6, 12 of this exemplary embodiment are spaced from the piston rod-side end and from the injector-side end of the injection cylinder 3, with the clearances 6, 12 being spaced from the piston rod-side end of the injection cylinder 3 along the longitudinal axis 4 by approximately 20% of the total length of the injection cylinder 3 along the longitudinal axis 4 are spaced.

The 4 and 5 already show that 3 known detail A from 1 in different operating states - more precisely in a maintenance position of the injection piston 5.

Thus, in a first step, the injection piston 5 is linearly displaced via the piston rod 9 into a retracted position relative to the injection cylinder 3, with the injection piston 5 being in the area of the release 6, 12. This retracted position is even further "rear" than the previously discussed "inject position".

This position is in 4 shown in a side view and in 5 in a top view.

When this position is reached, in a second method step, the injection piston 5 can be guided radially through the clearance 6 of the injection cylinder 3 in order (as in 4 indicated) to assemble or disassemble the injection piston 5.

The injection piston 5 is a form-fitting connection 10 - strictly speaking, a T-groove having groove connection - connected to the piston rod 9, so that by a radial movement of the injection pistons 5 can be released from the piston rod 9 merely by displacement or can be connected to the piston rod 9.

Provision can be made for the piston rod 9 and the injection piston 5, which is positively connected to the piston rod 9 via the T-groove, to be tilted about the longitudinal axis 4, preferably 90 degrees, during operation of the injection unit 1.

By appropriate tilting about the longitudinal axis 4, the injection piston 5 can also be secured in its position and in its connection with the piston rod 9, so that the injection piston 5 can also be moved into the retracted position (in which the injection piston 5 is below the clearance 6 and located above the further clearance 12) cannot be released from the positive connection with the piston rod 9 purely by gravity and can, for example, “fall” out of the injection cylinder 3 through the further clearance 12.

It is thus possible in this maintenance position or retracted position of the piston rod 9 and the injection piston 5 to easily remove the injection piston 5 via the clearance 6 (for example with the aid of a lifting device such as a crane), to replace it, to maintain it, to service or deliver.

Furthermore, it can be provided that the injection piston 5 itself has a second temperature control device, which second temperature control device is designed to temperature control the injection piston 5 to a predeterminable temperature.

By controlling the temperature of the injection piston 5, it can be provided that the temperature expansion of the injection piston 5 is controlled or regulated, as a result of which a gap size between the injection piston 5 and the injection cylinder 3 can be varied.

By varying the size of the gap between the injection piston 5 and the injection cylinder 3, the leakage can also be controlled or regulated, centering of the injection piston 5 in the injection cylinder 3 can be defined, or friction between the injection piston 5 and the injection cylinder 3 can be set.

The 6 until 8th show another embodiment of an injection unit 1 according to the invention, wherein 6 a frontal view, 7 a side view and 8th represents a view from above.

This embodiment of the 6 until 8th essentially corresponds to the exemplary embodiment of FIG 1 , where the 6 until 8th show a higher level of detail.

For example, it can be seen how the plasticizing unit 20 of the embodiment of FIG 6 until 8th is implemented as a plasticizing screw, with the drive unit 23 of the plasticizing unit 20 via a rotation plasticizing can be driven by the plasticizing screw.

By means of a linear movement of the drive unit 23, the plasticized plastic can then be fed via the plasticizing screw of the plasticizing unit 20 via the feed device 26 and the feed opening 16 of the injection unit 1 into the interior of the injection cylinder 3.

The injection unit 1 is supported via the pressing device 27 (formed by hydraulic piston-cylinder units) on a clamping unit 34 of the molding machine 2, as a result of which the injection nozzle 17 is pressed against a molding tool 32 (clamping unit 34 and molding tool 32 are included in these for reasons of clarity Figures not shown).

After filling the injection unit 1 with plasticized plastic by means of the plasticizing unit 20, the plasticized plastic can then be pushed out of the injection unit 1 by a linear movement of the drive unit 21 via the piston rod 9 and the injection piston 5 from the injection cylinder 3 and via the injection nozzle 17 into the mold 32 are injected.

Through 7 it can be seen that the plasticizing unit 20 is arranged laterally offset to the injection unit 1 in a view from above.

This positioning of the plasticizing unit 20 laterally offset above the injection unit 1 improves the accessibility of the clearance 6, with the injection plunger 5 being removed, for example, without the dismantling of surrounding components (of the plasticizing unit 20) by a lifting device (e.g. a crane) through the clearance 6 or can be supplied.

9 and 10 show perspective views of the embodiment of the 6 until 8th .

The 11 until 19 show a further exemplary embodiment of an injection unit 1. This exemplary embodiment essentially corresponds to the first exemplary embodiment in FIG 1 and 2 , The injection piston 5 being able to be tempered, preferably cooled, by means of the tempering media guide 38 .

11 shows a side view of the embodiment and 12 a view from above of the embodiment of an injection unit 1 of 11 .

The representations shown of the embodiment of 11 and 12 also differ in that 11 represents a state of the injection unit 1 loaded with a plasticized plastic mass and 12 an extended state of the injection unit 1.

13 provides a detailed view of the 14 represents and shows the embodiment of 11 and 12 , wherein the injection piston 5 and the piston rod 9 have been linearly displaced to a retracted position relative to the injection cylinder 3, in which retracted position the injection piston 5 is in a region of the injection cylinder 3 of the clearance 6 and the further clearance 12. 14 shows a side view of the 13 .

through the 13 is a view of the other embodiment can be seen (as well as by 12 shown), wherein the T-groove having groove connection 10 between injection piston 5 and piston rod 9 can be seen.

The temperature control media guide 38, designed as a "tube in tube" solution, is connected by the in 13 (in an enlarged detail view) clearly visible.

Through this tempering medium guide 38 , a tempering medium can be guided through an inner tube and an outer tube to a portion of a piston tip of the injection piston 5 and also removed again in order to be able to temper the injection piston 5 in the injection cylinder 3 .

The temperature control of the injection piston 5 in the injection cylinder 3 results in the essential advantage of influencing thermal expansion of the injection piston 5.

For example, a gap dimension between injection piston 5 and injection cylinder 3 can be influenced via the thermal expansion of injection piston 5 relative to injection cylinder 3 , as a result of which leakage between injection piston 5 and injection cylinder 3 can be minimized.

It could be provided, for example, that a gap size between the injection cylinder 3 and the injection piston 5 is measured and that the gap size is minimized by targeted adjustment of the temperature of the injection piston 5 (and thus a specifically influenced thermal expansion of the injection piston 5) via the tempering media guide 38, whereby the leakage over this gap dimension can also be minimized.

The temperature control media guide 38 designed as a "tube in tube" solution opens out via a central bore in the piston rod 9 in a likewise centrally located bore of the injection piston 5, with the outer tube of the temperature control media guide 38 being connected at an entrance into the central bore of the injection piston 5 via a Seal is sealed against leakage of the tempering medium guided in the tempering medium guide 38 .

The temperature control medium can, for example, be guided via the inner tube of the temperature control medium guide 38 to an area of the piston tip of the injection piston 5, in which case the temperature control medium can then be discharged again via the outer tube, with the temperature control medium flowing through the injection piston 5 and the piston rod 9 Injection piston 5 and the piston rod 9 can be tempered.

In order to be able to disassemble the injection piston 5, the temperature control medium guide 38 is pulled back into the piston rod 9 from the injection piston 5, which is in a retracted position (as shown in FIG 16 shown).

Provision can be made for the tempering medium guide 38 to be blown through with air or compressed air before it is pulled back (and thus before it is pulled out of the central bore of the injection piston 5), so that the tempering medium and any residues of the tempering medium are removed from the tempering medium guide 38.

After the tempering medium guide 38 has left the central bore of the injection plunger 5, the injection plunger 5 can be guided through the clearance 6 and thus dismantled from or assembled from the injection plunger (as shown by 15 is shown).

The embodiment of 11 and 12 has, as mentioned, a tempering medium guide 38 which is provided for tempering the injection piston 5 and preferably the piston rod 9 .

The in the 11 and 12 marked details B, C are through the 17 and 18 shown (detail B of the 1 is in 18 shown and detail C of 8th in 17 ) .

The temperature control medium guide 38 extends from a rear area of the injection unit 1 (more precisely: from a pressure plate of the injection unit connected to the injection cylinder 3) via a corresponding bore through the center of the piston rod 9 to an area of the piston syringe of the injection piston 5.

In the 19 The molding machine 2 shown by way of example is an injection molding machine and has an injection unit 1 and a clamping unit 34 which are arranged together on a machine frame 24 . Alternatively, the machine frame 24 could also be designed in several parts.

The clamping unit 34 has a stationary platen 29 , a movable platen 28 and a face plate 31 .

The movable platen 28 can be moved relative to the machine frame 24 via a toggle lever mechanism 30 shown symbolically.

Mold halves of a molding tool 32 can be clamped or mounted on the fixed platen 29 and the movable platen 28 (shown in phantom).

The fixed platen 29, the movable platen 28 and the end plate 31 are supported and guided by the bars 33 relative to one another.

This in 19 Mold 32 shown closed has at least one cavity. An injection channel leads to the cavity, via which a plasticized compound can be supplied to the injection unit 1 .

The injection unit 1 of this exemplary embodiment has an injection cylinder 3 and an injection piston 5 arranged to be linearly movable in the injection cylinder 3 .

The movements of the injection unit 1 are driven by a drive unit 21 shown schematically.

19 shows a molding machine 2 with an injection unit 1, the injection unit 1 shown in this exemplary embodiment being supplied with a plasticized plastic mass by the plasticizing unit 20 via the feed device 26.

The plasticizing unit 20 comprises a plasticizing screw arranged in the plasticizing cylinder, which is mounted so that it can be displaced axially along a longitudinal axis and rotated about the longitudinal axis (for a more detailed explanation of the plasticizing and injection, refer to the preceding description of the figures).

The plasticizing unit 20 and thus the injection unit 1 are connected to a control or regulating unit 35 in terms of signals. The control or regulating unit 35 outputs control commands, for example to the plasticizing unit 20, the drive unit 23, the injection unit 1 and the drive unit 21.

The control or regulation unit 35 can be connected to an operating unit and/or a display device 36 or can be an integral part of such an operating unit.

Reference List

1

injection unit

2

shaping machine

3

injection cylinder

4

longitudinal axis

5

injection piston

6

exemption

7

lateral surface

8th

Inside diameter of the injection cylinder

9

piston rod

10

groove connection

11

length of exemption

12

Further exemption

13

centerline

14

scraper ring

15

Another scraper ring

16

feed opening

17

injector

18

width of exemption

19

heating bands

20

plasticizing unit

21

Linear drive unit

22

collection container

23

Drive unit of the plasticizing unit

24

machine frame

25

hopper

26

feeding device

27

pressing device

28

Movable platen

29

Fixed platen

30

toggle mechanism

31

faceplate

32

molding tool

33

spar

34

locking unit

35

control or regulation unit

36

display device

37

flange

38

Tempering media guide

39

clamping

Claims (16)

Injection unit for a molding machine (2), comprising - an injection cylinder (3) which extends along a longitudinal axis and - an injection piston (5) arranged to be linearly displaceable in the injection cylinder (3) along the longitudinal axis (4), characterized in that the injection cylinder (3) has at least one clearance (6) which has a width (18) greater than/equal to a diameter of the injection piston (5), and that the injection piston (5) in a retracted position relative to the at least one clearance (6) is axially so is that the injection plunger (5) can be guided through the at least one clearance (6). injection unit claim 1 wherein the injection cylinder (3) has an inner diameter (8) having a lateral surface (7), the at least one clearance (6) being formed as the lateral surface (7) passing through the opening of the injection cylinder (3). Injection unit according to one of the preceding claims, wherein a piston rod (9) which is connected in a movement-locking manner to the injection piston (5) is provided and is designed to linearly displace the injection piston (5). injection unit claim 3 , wherein the injection piston (5) is or can be connected to the piston rod (9) by means of a positive connection, preferably a groove connection (10), particularly preferably a groove connection (10) having a T-groove. Injection unit according to at least one of the preceding claims, wherein the injection cylinder (3) has a piston rod-side end and an injector-side end along the longitudinal direction (4), the at least one clearance (6) being spaced from at least one of the two ends. injection unit claim 5 , wherein the at least one clearance (6) from the end of the injection cylinder (3) on the piston rod side along the longitudinal axis (4) is at least 0.1%, preferably 10%, particularly preferably 20%, of a total length of the injection cylinder (3) along the longitudinal axis (4 ) is spaced. Injection unit according to at least one of the preceding claims, wherein the at least one clearance (6) has a length (11) along the longitudinal axis (4) greater than/equal to a longitudinal extension of the injection piston (3) along the longitudinal axis (4). Injection unit according to at least one of the preceding claims, wherein the injection cylinder (3) has at least one further clearance (12), which is preferably arranged on the injection cylinder (3) opposite the at least one clearance (6), particularly preferably one around a center line (13) of the injection cylinder (3) mirrored exemption (12) which represents at least one exemption (6). Injection unit according to at least one of the preceding claims, preferably according to claim 8 , wherein the at least one clearance (6) on the injection cylinder (3) is arranged on an upper side and preferably the at least one further clearance (12) is arranged on an opposite underside. Injection unit according to at least one of the preceding claims, wherein at least one scraper ring (14, 15) is provided on the injection cylinder (3) in the at least one clearance (6), preferably on a side facing an injection-nozzle-side end of the injection cylinder (3). injection unit claim 10 , wherein the at least one scraper ring (14, 15) - is designed in at least two parts, the scraper ring (14, 15) preferably being divided along a plane containing the longitudinal axis (4), and/or - a first temperature control device, preferably one Heating device, which first temperature control device is designed to keep the at least one scraper ring (14, 15) at a predeterminable temperature, particularly preferably a temperature of the plasticized plastic mass, and/or - with a scraper edge, at least in certain areas, the piston rod ( 9) encloses. Injection unit according to at least one of the preceding claims, wherein the injection piston (5) has a second temperature control device, which second temperature control device is designed to temperature control the injection piston (5) to a predeterminable temperature. Injection unit according to at least one of the preceding claims, wherein the injection cylinder (3), preferably on a lateral surface (7) of the injection cylinder (3), has a feed opening (16) which is arranged in such a way that a through the injection piston (5) and the Injection cylinder (3) formed injection volume via the feed opening (16) a plasticized plastic mass can be fed. Injection unit according to at least one of the preceding claims, wherein an injection nozzle (17) is provided on an injection-nozzle-side end of the injection cylinder (3), a plasticized plastic mass being injected via the injection nozzle (17) by a linear displacement of the injection piston (5) relative to the injection cylinder (3 ) can be pushed out of the injection cylinder (3) via the injection nozzle (17). Shaping machine, in particular an injection molding machine, with at least one injection unit (1) according to at least one of the preceding claims. Method using an injection unit (1), preferably according to at least one of Claims 1 until 14 , comprising - an injection cylinder (3) which extends along a longitudinal axis (4) and - an injection piston (5) arranged to be linearly displaceable in the injection cylinder (3) along the longitudinal axis (4), the injection piston (5) and/or a Piston rod (9) is linearly displaced in a first method step into a retracted position relative to the injection cylinder (3) and in a second method step the injection piston (5) is radially displaced through at least one clearance (6) of the injection cylinder (3), which has at least one clearance ( 6) has a width (18) greater than/equal to a diameter of the injection plunger (5), is guided.

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