DE102014106410B4 - Process for the production of molded parts in an injection molding machine - Google Patents

Abstract

Method for producing molded parts (5) in an injection molding machine (1), wherein a flowable mass is supplied via at least two hot runner nozzles (11) to at least one cavity (31) formed in an injection mold (2), each hot runner nozzle (11) heating (13), and wherein each heater (13) is connected to a temperature control device (23), comprising the following steps: a) introducing the flowable mass into the at least one cavity (31) of the injection mold (2) via the at least two hot runner nozzles (11), b) curing the flowable mass in the at least one cavity (31), c) opening the injection mold (2), d) detecting the heat radiation and / or the temperature of all still in the injection mold (2) located moldings ( 5) in selected areas (51) of the molded parts (5) by means of a detection system (6), e) transmission of the detected values (W1-n) relating to the heat radiation and / or di e temperature to a data processing system (7), f) comparison of the values (W1-n) detected in the selected regions (51) of the at least one molded part (5) by the data processing system (7), g) determination of deviations (ΔW) h) assignment of the at least two hot runner nozzles (11) to the detected values (W1-n) by the data processing system (7), i) selection of at least one associated hot runner nozzle (1) between the detected values (W1-n) by the data processing system (7) 11) on the basis of the determined deviations (ΔW) between the detected values (W1-n) by the data processing system (7), j) activation of the heater (13) of the at least one selected hot runner nozzle (11) by the data processing system (7) via the Temperature control device (23), k) ejecting all moldings (5) from the injection mold (2).

Description

The invention relates to a method for producing molded parts in an injection molding machine according to claim 1.

Methods for the production of moldings in injection molding machines are known. Here, a flowable mass is supplied via at least two hot runner nozzles at least one formed in an injection mold cavity, each hot runner nozzle has a heater to heat the channels and keep the flowable mass guided therein at a predetermined temperature before it enters the cavities. The hot runner nozzles are usually mounted on a distributor plate, which also has at least partially heated channels. In order to detect the temperature of the channels or the heaters, temperature sensors are provided.

Each heater and each temperature sensor is connected to a temperature control device, with a separate control circuit usually being provided for each heater. The temperature control unit is responsible for the tempering of the heated channels, so that the flowable mass is always injected into the cavity at a constant and optimum temperature. For this purpose, a temperature setpoint is set for each heater or for each control loop, on which the associated hot runner nozzle or the associated channel section or manifold is maintained.

For a variety of reasons, for example due to design flaws on the tool, on the hot runner nozzles or on the manifolds, or in the formation and location of the channels, or due to improperly positioned heaters or temperature sensors, it may happen that the flowable mass has different temperatures, i. not balanced, injected into the cavities. This can lead to quality losses in the moldings or even to rejects, which has an unfavorable effect on the production costs.

To counter this, for example, it is off DE 10 2006 027 028 A1 known to continuously monitor the manufacturing process by means of a thermal imaging camera. For this purpose, a thermal image is taken of each demoulded and removed from the mold plastic molding with the thermal imaging camera, which is compared with one or more reference thermal images. In the case of exceeding a preset threshold, a signal is triggered, which leads to a separation of the corresponding plastic molded part, to stop the manufacturing process or to readjust the manufacturing process.

At an in DE 10 2010 042 759 A1 In the case of the disclosed method, a thermal image is likewise recorded by a thermoformed camera which is completely removed from the mold and removed from the mold, which is then compared in a control device with an associated reference thermal image. From these data, a differential thermal image is calculated, which serves to control at least one tempering circuit of a tempering system of the mold. In this way, temperature differences in the production of a corresponding plastic molding to be minimized in a subsequent manufacturing cycle.

DE 10 2009 001 682 A1 describes a method for controlling an injection molding process with the aid of time and temperature-dependent shrinkage curves, which were determined from images of an injection molded part taken from an injection mold. Also in this method, the measurement is carried out after demolding and ejection of the produced plastic molding.

DE 102 61 498 A1 discloses a method in which the dimensions, the surface finish and / or the color of the molded part are detected by means of an optical detection element preferably arranged outside the injection molding tool. The determined values are compared with a reference value and used to generate control signals for the injection molding machine. This results in a control of the temperature of the melt and the mold plate and the injection pressure. The determination of the parameters takes place on already produced ejected injection molded part, which is fed by means of a handling system to the detection instrument.

JP H11 28 744 A discloses a method in which the heaters of the hot runner nozzles are controlled based on a temperature distribution determined by infrared measurement. However, the measurement is not done on the plastic molding but on a part of the injection molding machine.

In the known method, a thermographic examination is carried out after demolding and ejection of the produced plastic molded part. In the process, however, cooling takes place at least in partial areas of the plastic molded part in the time until the first thermal image is taken up, so that a heat distribution of the molded part is always determined, which differs from the heat distribution that the molded part has immediately after the completion of the manufacturing process within the injection molding tool having.

Furthermore, the plastic molded part in the previously known method after Ejecting be transported to the receiving area of the thermal imaging camera, z. B. using a gripping or removal system, which further falsifies the heat distribution in the molding. Furthermore, the molded part must be correctly positioned in the receiving area in order to produce the necessary thermal image. As a result, increased demands are made on the structure and on the programming of a gripping or removal system, so that a secure transport from the cavity to the receiving area and always the same position of the plastic molded part are ensured in the receiving area.

The invention is therefore based on the object to overcome these and other disadvantages of the prior art and to develop a method for the production of moldings in an injection molding machine, with which a consistently high quality of the molded parts produced is ensured. The aim is in particular a thermal balancing of all cavities within the injection mold, the method should be simple and inexpensive to carry out by economic means.

Main features of the invention are specified in the characterizing part of claim 1. Embodiments are the subject of claims 2 to 15.

• a) Einbringen der fließfähigen Masse in die wenigstens eine Kavität des Spritzgießwerkzeugs über die wenigstens zwei Heißkanaldüsen,
• b) Aushärten der fließfähigen Masse in der wenigstens einen Kavität,
• c) Öffnen des Spritzgießwerkzeugs,
• d) Erfassen der Wärmestrahlung und/oder der Temperatur aller sich noch in dem Spritzgießwerkzeug befindlichen Formteile in ausgewählten Bereichen der Formteile mittels eines Erfassungssystems,
• e) Übermittlung der erfassten Werte betreffend die Wärmestrahlung und/oder die Temperatur an ein Datenverarbeitungssystem,
• f) Vergleich der in den ausgewählten Bereichen des wenigstens einen Formteils erfassten Werte durch das Datenverarbeitungssystem,
• g) Ermittlung von Abweichungen zwischen den erfassten Werten durch das Datenverarbeitungssystem,
• h) Zuordnung der wenigstens zwei Heißkanaldüsen zu den erfassten Werten durch das Datenverarbeitungssystem,
• i) Auswahl wenigstens einer zugeordneten Heißkanaldüse anhand der ermittelten Abweichungen zwischen den erfassten Werten durch das Datenverarbeitungssystem,
• j) Ansteuerung der Heizung der wenigstens einen ausgewählten Heißkanaldüse durch das Datenverarbeitungssystem über das Temperaturregelgerät,
• k) Auswerfen aller Formteile aus dem Spritzgießwerkzeug.

As a solution, the invention proposes a method for the production of moldings in an injection molding machine in which a flowable mass is supplied via at least two hot runner nozzles at least one formed in an injection mold cavity, each hot runner nozzle has a heater, and wherein each heater is connected to a temperature control device is. This method according to the invention comprises the following steps:

• a) introducing the flowable mass into the at least one cavity of the injection mold via the at least two hot runner nozzles,
• b) curing the flowable mass in the at least one cavity,
• c) opening the injection mold,
• d) detecting the heat radiation and / or the temperature of all the mold parts still in the injection mold in selected areas of the mold parts by means of a detection system,
• e) transmission of the detected values relating to the heat radiation and / or the temperature to a data processing system,
• f) comparison of the values recorded in the selected regions of the at least one molded part by the data processing system,
• g) determination of deviations between the detected values by the data processing system,
• h) assignment of the at least two hot runner nozzles to the detected values by the data processing system,
• i) selecting at least one associated hot runner nozzle based on the determined deviations between the detected values by the data processing system,
• j) controlling the heating of the at least one selected hot runner nozzle by the data processing system via the temperature control device,
• k) ejecting all moldings from the injection mold.

With this inventive method is achieved in a surprisingly simple manner that the temperature set values, which are the temperature control device the heaters of the hot runner nozzles - and if present, the heaters of a distributor - given corrected after a completed injection molding cycle such that during the following Cycles all moldings thermally balanced and thus all cavities are thermally balanced with each other. In contrast to the methods known from the prior art, it is no longer necessary to install complicated and expensive sensor systems within the cavities, ie. It must be measured neither pressures nor temperatures in the cavities, which significantly reduces the apparatus design and thus the cost of the injection mold.

Rather, with the method according to the invention, the control loop of the heating systems for the hot runners, in particular for the hot runner nozzles, is extended such that the heat radiation and / or the temperature of all mold parts still in the injection mold is detected in selected areas by using a detection system outside the injection mold, and immediately after opening the tool and before ejecting the moldings. The detected values are transmitted to a data processing system, which compares the values detected in the selected regions of the at least one molded part with one another and determines deviations between the detected values.

In order to be able to make a targeted correction of the individual temperature setpoints via the temperature control device on the basis of the determined values and the calculated deviations, at least one hot runner nozzle is assigned to each detected value. Then, based on the determined deviations between the detected values, at least one of these associated hot runner nozzles is selected, ie it is determined which hot runner nozzle is responsible for a resulting or existing deviation. This can - depending on the division of the cavities and depending on the geometry of the Moldings - be several hot runner nozzles. Conversely, a hot runner nozzle can be the cause of temperature deviations in several cavities. If a deviation has been detected for a detected value and a hot runner nozzle of the data processing system assigned a different value, the heating of this hot runner nozzle is controlled by the data processing system via the temperature control device, for example, the temperature setpoint for this hot runner nozzle - depending on the nature of the deviation the control circuit is lowered or raised.

The detected values relating to the heat radiation and / or the temperature in the selected regions of the moldings are thus detected and processed by the data processing system such that the deviations determined cause a correction of the temperature setpoints for the individual heaters of the hot runner nozzles and, if necessary, also the manifolds so that all moldings in the injection mold are exposed to an always comparable thermal manufacturing process.

The fact that the detection of the heat radiation or the temperature takes place even before the ejection of the moldings, on the one hand prevents the moldings from significantly cooling or thermally changing even before the values are recorded and, on the other hand, that the values relating to heat radiation and / or or the temperature can not be falsified by foreign bodies or foreign equipment. Rather, a timely thermal analysis of the moldings in the tool, so that always consistently high quality of all moldings achieved and no or little waste is produced by the inventive method. This has an extremely favorable effect on the production costs of the molded parts.

Depending on the timing of the injection molding process, steps a) to k) of the process according to the invention are carried out in each production cycle or after a defined number of production cycles. This depends, for example, on how many production cycles are performed per unit of time.

Preferably, at least one hot runner nozzle is associated with each cavity in an injection mold for the injection molding machine. It can be provided per cavity exactly one hot runner nozzle, for example in a multiple tool with 4, 8, 16, 32 or 64 cavities. But it can also - depending on the molding - for each cavity a plurality of hot runner nozzles and thus several injection points may be provided to form, for example, a Mehrfachanspritzen or a Kaskadenanguss. It is also possible that a hot runner nozzle, for example a multi-nozzle serves several cavities.

It is important that at least one selected area is assigned to each molded part, so that representative values relating to the heat radiation and / or the temperature can be determined. Depending on the size and geometry of the molded parts, it may be expedient to assign each molded part exactly a selected area. For larger or more complex components, on the other hand, it is advantageous if two or more selected areas are assigned to each molded part in order to ensure always precise thermal balancing of the tool. It is also important here that at least one hot runner nozzle is assigned to each selected area in order to be able to select and control the corresponding control loop of the affected heating of the hot runner nozzle on the basis of this assignment. It does not matter if the moldings are injected straight or sideways or from behind. It also does not matter whether open hot runner nozzles or needle valve nozzles are used. A hot runner nozzle may also have a plurality of heaters that can be controlled together or separately, for example in the shaft area and in the nozzle tip area.

An embodiment of the method according to the invention provides that the detection system detects the values relating to the heat radiation and / or the temperature in the selected regions of the molded parts without contact. As a result, the heat distribution within the molding - in contrast to conventional methods which grip the mold parts to remove them from the tool - neither influenced nor falsified, which further has a favorable effect on the thermal balance of the cavities within the injection mold.

According to a further embodiment of the method according to the invention, the detection system detects the values relating to the heat radiation and / or the temperature in the selected regions of the molded parts after a defined time interval, namely when the tool has reached an optimal open position and / or the detection system has reached a predetermined position , In this case, it is also expedient if the detection system records the values relating to the heat radiation and / or the temperature in the selected regions of the molded parts at the same time. This also largely avoids environmental influences or falsifications of the measured values.

Preferably, the detection system detects the heat radiation of the moldings, ie, a thermographic measurement is made. This is for example a thermal imaging camera used, whose heat spectrum is in the infrared range. Accordingly, the detection system has a thermal imaging camera. Alternatively or additionally, cameras can also be used whose recording medium is sensitive to the visible spectrum of the light. It is particularly economical in terms of process if only one camera is used, with which a thermal image, ie a temperature distribution over all molded parts produced using the injection molding tool, is produced. Such cameras are easy to use and relatively inexpensive to purchase and maintain. The maintenance or repair of a camera is particularly easy to carry out if it is located outside of the injection mold.

Another embodiment of the method according to the invention provides that the detection system detects the absolute or relative temperature of the molded parts, wherein the detection system has at least one temperature sensor. Preferably, thermocouples or thermocouples are used. Also suitable are thermographic sensors. Appropriately, a separate temperature sensor is provided for each selected area, so that a simultaneous measurement can also be performed here. The temperature sensors may also touch the mold parts for a defined period of time during the measurement. As a result, the necessary values are recorded quickly and precisely, but without distorting the temperature distribution and thus the measurement.

In an advantageous development of the method according to the invention, the data processing system uses the acquired values concerning the heat radiation and / or the temperature to produce a heat radiation or temperature profile of the at least one molded part or of the molded parts. This profile can then be further analyzed by the data processing system, e.g. the data processing system compares the generated heat radiation or temperature profile with a stored heat radiation or temperature profile, for example by means of an image analysis. If deviations in the individual values are determined here, the selection of at least one hot runner nozzle according to step i) of the method according to the invention is carried out on the basis of these deviations. Subsequently, the control loop of the affected heating of the at least one selected hot runner nozzle according to step j) is controlled by the data processing system, wherein the temperature control device adjusts the heating accordingly. If the molding is too hot in the selected area, the temperature setpoint for the associated hot runner nozzle will be lowered. If the selected range is too cold, the temperature setpoint of the associated hot runner nozzle is raised accordingly.

Suitably, each deviation is a difference between the detected values of two selected regions. Additionally or alternatively, it is provided that the data processing system compares each detected value with a predetermined target value and the deviation is calculated as the difference between the detected value and the target value.

In accordance with the determined deviation of the temperature in a selected region, the heating of the associated hot runner nozzle responsible for this purpose is preferably readjusted via the temperature control device in which the temperature of the heating of the selected hot runner nozzle is adjusted according to upper or lower.

Constructively, it is advantageous if the data processing system is integrated in the temperature control device. This also reduces the expenditure on equipment.

The transmission of the detected values relating to the heat radiation and / or the temperature can be transmitted by data line from the detection system to the data processing system. However, the values can also be transmitted via a radio link, for which purpose the detection system and the data processing system are equipped with suitable transmitters and receivers.

Overall, a consistently high quality of the produced plastic molded parts is ensured with the inventive method in a particularly simple, efficient and reliable manner.

Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. Show it:

1 A flow chart of a method according to the invention for the production of moldings in an injection molding machine, and

2 a schematic representation of an apparatus for carrying out the method according to the invention for producing a molded part.

1 shows a flow chart of a method according to the invention for the production of moldings 5 in an injection molding machine 1 , Such an injection molding machine 1 is for example in 2 shown schematically. The structure and operation of such an injection molding machine 1 is in itself well known.

The injection molding machine 1 has an injection mold 2 , the two halves of the tool 3a and 3b having. These form together mold 3 in which cavities 31 are formed. During the injection of the material to be processed, for example a plasticizable plastic mass, into the cavities 31 is the mold 3 closed. For ejecting the finished molded parts 5 however, the mold becomes 3 - as in 2 shown - opened in a parting plane. 2 therefore shows the mold 3 and thus the injection mold 2 in the open position before ejecting the moldings 5 ,

The first tool half 3a of the mold 3 is the so-called "cold side". It has a (unspecified) tool plate, in the example, two cavities 31 are formed. In the field of cavities 31 in the tool plate usually (not shown) formed channels through which a cooling medium is passed to the moldings 5 to cool down after injecting the plastic mass.

The second half of the mold 3b is the so-called "hot side". This has a (also unspecified) tool plate, in the two hot runner nozzles 11 are used, each hot runner nozzle 11 a cavity 31 in the first half of the mold 3a assigned.

Each hot runner nozzle 11 has a nozzle body 12 , the peripheral with a heater 13 is provided. Centric in the nozzle body 12 is a flow channel 14 formed to the processed plastic mass of each associated cavity 31 supply. The latter is provided for this purpose with a (not shown) gate. The flow channels 14 ending in (not shown) nozzle tips, which are usually made of a highly heat conductive material, all nozzle tips with closed mold 3 Centric in front of the gate openings of the cavities 31 lie. At the opposite end is every nozzle body 12 with a flange 15 on a distributor plate 20 attached, which receives the plastic mass to be processed by a (not shown) machine nozzle and a channel system 21 the individual hot runner nozzles 11 supplies. The channel system 21 is with separate heaters 22 Mistake.

The heaters 13 the hot runner nozzles 11 and the heaters 22 the distributor plate 20 are via (unspecified) connecting leads to a temperature control device 23 connected, which is equipped with an electronic control. The latter is preferably designed such that each heater 13 . 22 Part of an independent control loop is. This makes it possible to any heating 13 . 22 individually to control and bring to a predetermined temperature, usually a temperature setpoint is specified, for example, in a memory of the temperature control device 23 is stored and via a control panel on the temperature control unit 23 can be adjusted. To monitor compliance with the temperature setpoints, there are at each hot runner nozzle 11 and in the distributor plate 20 (not shown) formed temperature sensor, which also to the temperature control device 23 are connected, each temperature sensor is integrated in the associated control loop.

The injection mold 2 , this in 2 is shown schematically and very simplified, can - as described - be designed as a dual tool. The number of hot runner nozzles 11 and the number of cavities 31 However, it can be increased arbitrarily, for example, for each cavity 31 exactly one hot runner nozzle 11 and a gate is provided. However, it can also be several hot runner nozzles 11 a cavity over several gate openings 31 spraying, either simultaneously or - depending on the product and its geometry - in the cascade casting. It is also conceivable the assignment of a hot runner nozzle 11 to several cavities 31 by using, for example, a multiple nozzle.

Outside the injection mold 2 is a detection device 6 intended. This serves to detect the thermal radiation of all still in the injection mold 2 located moldings 5 , wherein the detection device 6 is formed such that this after opening the injection mold 2 near the moldings 5 can be brought into a distance that provides a reliable and uniform detection of the moldings 5 outgoing heat radiation allowed. The detection device 6 is further formed such that the heat radiation of each molding 5 in a selected area 51 is detected, ie it is not necessary, the entire thermal radiation of a molded part 5 capture. Rather, it is sufficient to heat radiation in a selected, especially limited area 51 take.

At the detection device 6 For example, it is an IR thermographic thermal imaging camera provided with respective sensors or sensor fields, preferably for each molding 5 and for each selected area 51 the molded parts 5 a sensor or a sensor field is provided. The selected areas 51 the molded parts 5 can be wall or edge areas, with the tool open for the detection device 6 are easily accessible from the outside. Depending on the design and geometry of the cavity 31 , can be a selected area 51 a molding 5 located in the area of the gating point. However, if this is difficult to access or even inaccessible in the tool, another area of the molding is 5 selected. Are mold inserts in the mold 32 provided, these can after opening of the injection mold 2 and before using the detector 6 be removed to other or other selected areas 51 on the molding 5 to make accessible. The detection device 6 can be compared to the injection mold 2 be mounted fixed or it is by means of a (not shown) device in the opened injection mold 2 pivoted or positioned relative thereto.

The detection device 6 is via a connection cable 61 or a wireless link (not shown) to a data processing system 7 connected. This preferably has (not shown) a processor, a memory and, if necessary, a display device. The system 7 takes over from the detection device 6 recorded values W _{1-n of} the heat radiation of the individual molded parts 5 and process them electronically. In particular, the values W _{1 -n} from the data processing system 7 compared with each other, saved and the individual heaters 13 the hot runner nozzles 11 assigned. The data processing system 7 can be that of the detection system 6 Also, to process sensed values W _1-n into a heat radiation or temperature profile, or to generate a thermal image that is also stored and evaluated.

As 2 further shows is the data processing system 7 via a connecting cable 71 , or a radio link, to the temperature control device 23 connected, in particular to the trained therein control circuits for the heaters 13 . 22 the hot runner nozzles 11 and the distributor 20 , You can use the data processing system 7 but also in the temperature control unit 23 integrate, which reduces the expenditure on equipment.

The described injection molding machine 1 is intended for carrying out the method according to the invention. This basically provides that the flowable mass through the hot runner nozzles 11 in the injection mold 2 trained cavities 31 is fed, the heater 13 every hot runner nozzle 11 to the temperature control unit 23 is connected and brought by this to a certain predetermined target temperature and maintained.

In a first step a) of the method according to the invention, the flowable mass is - after closing the injection mold - on the hot runner nozzles 11 into the cavities 31 of the injection mold 2 introduced, preferably injected. Subsequently, in a step b), the hardening of the flowable mass takes place in the cavities 31 , resulting in the finished molded parts 5 arise. "Curing" does not mean that the mass must be completely through-hardened. It is enough, the moldings 5 inside the cold side 3a cool down so far that this after completion of the method according to the invention from the injection mold 2 can be ejected. When this condition is reached, the injection mold becomes 2 opened in a step c). The moldings 5 However, this is not yet out of the injection mold 2 ejected.

In a further step d) is now with the detection system 6 the thermal radiation of all still in the injection mold 2 located moldings 5 in the selected areas 51 the molded parts 5 captured, wherein the thermal imaging camera, the heat radiation of the moldings 5 picks up and for each selected area 51 generates a value W _n , so that total 1 until n values W _{1-n are} generated. The values W _1-n relating to the heat radiation in the selected areas 51 the molded parts 5 are preferably detected without contact and after opening the injection mold after a defined time interval at the same time. However, it is also possible to record the values W _{1 -n} in a specific or selected order.

After receiving the heat radiation values W _{1 -n} by the detection system 6 In a step e), the values W _{1 -n are sent} to the data processing system 7 which stores and further processes the values W _1-n . For example, the data processing system creates 7 on the basis of the detected values W _1-n a heat radiation profile or a thermal image showing the temperature distribution of the individual molded parts 5 represents. Subsequently, the data processing system compares 7 in a step f) in each of the selected areas 51 of the molded parts detected W _1-n , with deviations ΔW between the detected values W _{1-n are} determined (step g), in particular between two values W _n and W _{n + 1} .

The comparison of the values W ₁ -n may take place in a single comparison, each deviation ΔW always being a difference between the detected values W _n and W _{n + 1 of} two selected ranges 51 the molded parts 5 is. Additionally or alternatively, the individual values W _{1 -n} of the data processing system 7 be compared with a stored reference or reference value W _S. This is calculated by the data processing system 7 the deviations ΔW each as a difference between a detected value W _1-n and the desired value W _S. It is also conceivable that the data processing system 7 the generated heat radiation profile or the thermal image of all molded parts 5 is compared with a stored heat radiation profile as a reference profile in order to determine deviations ΔW between the individual values W ₁ -n from this image comparison.

Once all the values W _1-n are captured and saved and the values existing between the values Deviations ΔW are determined and stored, in the next step h) an assignment of the hot runner nozzles takes place 11 to the detected values W _{1 -n} by the data processing system 7 ie it defines which hot runner nozzle 11 which cavity 31 has filled and therefore what heating 13 from which hot runner nozzle 11 for the particular temperature of the molded part 5 in the relevant cavity 31 responsible for. If deviations ΔW are present, the data processing system selects 7 in a further step i) based on a determined deviation ΔW between the detected values W ₁ -n at least one of the selected ranges 51 assigned hot runner nozzle 11 out, ie the data processing system 7 identifies all hot runner nozzles 11 of the injection mold 2 which is responsible for a temperature deviation in the cavities 31 or in the moldings 5 are responsible. Then controls the data processing system 7 in a further step j) the heating 13 the selected hot runner nozzle 11 on, via the temperature control device 23 the heating system 13 or whose temperature is readjusted by, for example, the temperature setpoint for the relevant heating 13 is changed or by intervening directly in the control loop.

In a final step k) all moldings 5 from the injection mold 2 ejected. Thereafter, steps a) to j) may be carried out again. Alternatively, however, it is also possible, after a complete execution of all steps a) to k), first to carry out only steps a) to c) and k) for one or more injection molding cycles, and only after a certain time interval does the temperature distribution in the cavities 31 to check using the method according to the invention and possibly existing temperature deviations by intervention of the data processing system 7 in the control circuits of the temperature control device 23 balance.

The assignment of the hot runner nozzles 11 to the selected areas 51 The molded parts according to step h) need not necessarily follow step g), namely after the determination of the deviations ΔW between the individual values W _1-n . It is also possible to carry out the assignment between step e) and f) or even before step d).

In another embodiment of the method according to the invention may instead of the heat radiation directly the temperature of the moldings 5 be detected, the detection system 6 for this purpose has at least one temperature sensor. The data processing system 7 then creates a temperature profile of the molded parts on the basis of the detected temperature values W _1-n 5 ,

The invention is not limited to one of the above-described embodiments, but can be modified in many ways. So can the hot runner nozzles 11 For example, be designed as a needle valve nozzles or as open nozzles. The use of hot runner nozzles for the Seitenanguss is also conceivable.

In yet another variant of the method according to the invention can be dispensed with the formation of separately to be mounted hot runner nozzles completely by the flow channels for the mass to be processed, for example, directly in the tool plate of the hot side 3b are formed. It is crucial that each arranged along the flow channels heating via the temperature control device 23 and the data processing system 7 can be influenced to the occurrence of a temperature deviation on the moldings 5 , the responsible for heating 13 to be able to readjust. In order to identify the responsible for the temperature deviation heating to be with the detection device 6 Heat radiation values or temperature values of the molded parts 5 captured and from the data processing system 7 evaluated by software and displayed on demand on a screen. If deviations are detected, the data processing system intervenes 7 directly into the control circuits of the temperature control unit 23 one, causing the individual cavities 31 in the injection mold 2 be thermally balanced.

The nozzles 11 can - depending on the material to be processed - also be designed as cold runner nozzles. In this case, every nozzle is 11 provided with a cooling device by the temperature control device 23 and the data processing system 7 be controlled accordingly, it should turn out that in the selected areas 51 the molded parts 5 detected values W _1-n do not all match.

It can be seen that in a process for the production of molded parts 5 in an injection molding machine 1 a flowable mass over at least two hot runner nozzles 11 at least one in an injection mold 2 trained cavity 31 is fed, each hot runner nozzle 11 a heater 13 and where each heater 13 to a temperature control device 23 connected. For a thermal balancing of all cavities 31 inside the injection mold 2 to achieve, it is provided that the heat radiation and / or the temperatures of all are still in the injection mold 2 located moldings 5 in selected areas 51 the molded parts 5 by means of a detection system 6 be recorded. These in the selected areas 51 the at least one molding 5 acquired values W _{1 -n} are sent to a data processing system 7 transmitted and compared by this, deviations ΔW between the detected values W _{1-n are} determined. After assignment of the at least two hot runner nozzles 11 to the detected values W _1-n selects the data processing system 7 Based on the determined deviations ΔW between the detected values W _1-n at least one associated hot runner nozzle 11 from, in particular those, which for the deviation .DELTA.W in the cavity in question 31 responsible for. Subsequently, the data processing system controls 7 the heating system 13 the at least one selected hot runner nozzle 11 via the temperature control unit 23 so that the deviation .DELTA.W in the heat radiation and / or the temperature of the relevant molding 5 is compensated.

LIST OF REFERENCE NUMBERS

W _1-n

value

.DELTA.W

deviation

W _s

 Setpoint / reference value

1

injection molding machine

2

injection mold

3

mold

3a

Cold side

3b

Hot side

31

cavity

32

mold insert

5

molding

51

Selected area (molding)

6

acquisition system

61

connecting cable

7

Data processing system

11

hot runner nozzle

12

nozzle body

13

heater

14

flow channel

15

flange

20

distribution plate

21

channel system

22

heater

23

Temperature control device

Claims (15)

Process for the production of molded parts ( 5 ) in an injection molding machine ( 1 ), wherein a flowable mass via at least two hot runner nozzles ( 11 ) at least one in an injection mold ( 2 ) formed cavity ( 31 ), each hot runner nozzle ( 11 ) a heater ( 13 ), and wherein each heater ( 13 ) to a temperature control device ( 23 ), comprising the following steps: a) introducing the flowable mass into the at least one cavity ( 31 ) of the injection molding tool ( 2 ) via the at least two hot runner nozzles ( 11 b) curing the flowable mass in the at least one cavity ( 31 ), c) opening the injection mold ( 2 ), d) detecting the thermal radiation and / or the temperature of all still in the injection mold ( 2 ) moldings ( 5 ) in selected areas ( 51 ) of the molded parts ( 5 ) by means of a detection system ( 6 e) transmission of the recorded values (W _1-n ) concerning the heat radiation and / or the temperature to a data processing system ( 7 ), f) comparison of the selected areas ( 51 ) of the at least one molded part ( 5 ) detected values (W _{1 -n} ) by the data processing system ( 7 g) determining deviations (ΔW) between the detected values (W _1-n ) by the data processing system ( 7 ), h) assignment of the at least two hot runner nozzles ( 11 ) to the detected values (W _{1 -n} ) by the data processing system ( 7 i) Selection of at least one associated hot runner nozzle ( 11 ) on the basis of the determined deviations (ΔW) between the detected values (W _1-n ) by the data processing system ( 7 ), j) control of the heating ( 13 ) of the at least one selected hot runner nozzle ( 11 ) by the data processing system ( 7 ) via the temperature control device ( 23 ), k) ejecting all molded parts ( 5 ) from the injection mold ( 2 ). Method according to claim 1, characterized in that each cavity ( 31 ) at least one hot runner nozzle ( 11 ) assigned. Method according to claim 1 or 2, characterized in that each molded part ( 5 ) at least one selected area ( 51 ) assigned. Method according to one of claims 1 to 3, characterized in that each selected area ( 51 ) at least one hot runner nozzle ( 11 ) assigned. Method according to one of claims 1 to 4, characterized in that the detection system ( 6 ) the values (W _1-n ) relating to the heat radiation and / or the temperature in the selected regions ( 51 ) of the molded parts ( 5 ) detected without contact. Method according to one of claims 1 to 5, characterized in that the detection system ( 6 ) the values (W _1-n ) relating to the heat radiation and / or the temperature in the selected regions ( 51 ) of the molded parts ( 5 ) after a defined time interval. Method according to one of claims 1 to 6, characterized in that the detection system ( 6 ) the values (W _1-n ) relating to the heat radiation and / or the temperature in the selected regions ( 51 ) of the molded parts ( 5 ) recorded at the same time. Method according to one of claims 1 to 7, characterized in that the detection system ( 6 ) the thermal radiation of the molded parts ( 5 ) detected. Method according to claim 8, characterized in that the detection system ( 6 ) has a thermal imaging camera. Method according to one of claims 1 to 7, characterized in that the detection system ( 6 ) the temperature of the molded parts ( 5 ), the detection system ( 6 ) has at least one temperature sensor. Method according to one of claims 1 to 10, characterized in that the data processing system ( 7 ) on the basis of the detected values (W _1-n ) relating to the thermal radiation and / or the temperature, a heat radiation or temperature profile of the at least one molded part ( 5 ) or molded parts ( 5 ) created. Method according to claim 11, characterized in that the data processing system ( 7 ) compares the generated heat radiation or temperature profile with a stored heat radiation or temperature profile. Method according to one of Claims 1 to 12, characterized in that each deviation (ΔW) is a difference between the detected values (W _1-n ) of two selected regions (ΔW). 51 ). Method according to one of claims 1 to 13, characterized in that the data processing system ( 7 ) compares each detected value (W _1-n ) with a predetermined set value (W _S ) and calculates the deviation (ΔW) as the difference between the detected value (W _1-n ) and the set value (W _S ). Method according to one of claims 1 to 14, characterized in that the temperature control device ( 23 ) the temperature of the heating ( 13 ) of the selected hot runner nozzle ( 11 ) readjusted.

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