WO2018134091A1

WO2018134091A1 - Method and device for operating an injection moulding machine

Info

Publication number: WO2018134091A1
Application number: PCT/EP2018/050502
Authority: WO
Inventors: Marco Gruber; Norbert Heyer; Andreas HANDSCHKE
Original assignee: Kraussmaffei Technologies Gmbh
Priority date: 2017-01-20
Filing date: 2018-01-10
Publication date: 2018-07-26
Also published as: DE102017101132A1

Abstract

The aim of the invention is to regulate the starting processes regularly affecting empirically determined sequences, while reducing the quantity of the previously described additional arisings and the related costs of material, energy and system time. To this end, characteristics of a steady state of a respective production process are used to determine and adjust a respective number of injection cycles.

Description

Method and device for operating an injection molding machine

The present invention relates to a method and apparatus for operating an injection molding machine.

Various approaches for methods and apparatus for operating injection molding machines while optimizing both a material and energy requirement, as well as a power stroke are known from the prior art. Particularly noteworthy is a known from DE 10 2013 1 1 1 257 B3 process for process control of a mold filling an injection molding machine, based on a steady state in the current production of an injection molding machine volumetrically correct filling a mold cavity of each mold even with changing Environment parameters in an optimal range keeps to continuously produce products without errors or so-called good parts.

However, this known as "APC" method of the Applicant only regulates an ongoing injection molding process and thus can only intervene during a continuous production with a particular tool. If, however, production interruptions occur, as may occur, for example, as a result of a malfunction in the tool or the machine, but also due to shift changes, weekend breaks or other business interruptions, then a pending start-up process is a largely unregulated operating situation in each injection molding machine. Such processes of restarting on the same or on a modified injection mold are generally based on empirically determined processes, which are accordingly not necessarily reproducible or optimally adjusted. In the context of such start-up processes, the melt that has remained in the injection molding machine for a respective standstill phase must be completely ejected. Due to downtimes in the range of about 20 minutes to even over several hours away remaining in a plasticizing the respective injection molding machine residual material has changed by a permanent heating or a continuous entry of heat energy or even partially degraded. Already when setting up tools there is a plasticized material ready for processing is present, much longer in a plasticizing unit and theoretically degrades or degenerates. Regularly occurs in the course of any excessive heating by too long residence time of plasticizing material in a plasticizing unit of an injection molding machine, a shortening of molecular chain lengths within the plasticized material. This is accompanied by significant changes in the properties of the plasticized material, starting with color changes to altered material properties, such as a shift of solidification points or an increased ability of adhesive adhesion of the material within an injection mold.

Already to protect the partially very complex and thus possibly due to material changes within the plasticizable injutable injection molds, it is necessary that in the plasticizing unit of the injection molding leftover residual material in the course of a startup process completely removed from the plasticizing unit and new or fresh and in a temporal Process correctly molten material is replaced. This is done regularly by a so-called. Cumshot, wherein a separation between a tip of the actual injection molding machine and the associated tool under discharge of the material contained in the plasticizing unit is made outside. The screw threads within the plasticizing unit are flushed by spraying with new granules and fresh melt formed therefrom. When spraying the melt into the open, of course, this lost and regularly not reusable material is collected in a container and there optionally also cooled extra. Depending on a particular injection molding machine used and a downtime but significant amounts of waste material can be generated here.

It is an object of the present invention to regulate the starting processes based on empirically determined processes while reducing the amount of the additional scrap material described above and the associated costs of material, energy and system time.

This object is achieved by the features of the independent claims characterized in that a use of key figures from a settled State of a respective production process is performed in order to determine and set a respective number of Abspritz cycles, which implies an adjustment of a regulation. According to the invention, a method for controlling a startup process provides for the use of key figures from a steady state state of a respective production process. On this basis, an assessment, optimization and control of a respective startup process is performed.

Advantageous developments are the subject of the respective dependent claims. Accordingly, the key figures of the respective production process are also obtained by comparison with those of similar production processes. In doing so, a similar production process with respect to the specific properties i.a. a pairing of a respective tool and a used injection molding machine determined.

According to one embodiment of the invention, the key figures are obtained using key figures from an "APC" module and / or using a database. Here too, in addition to an existing production process, similar production processes can be used to further expand the database.

Preferably, an optimization is carried out using so-called melt state information, which are used on the basis of "APC" key figures for the control and regulation of a spraying program.

In a further development of the invention, further characteristic numbers or indices for a fast start-up process are determined and used. In particular, these new figures take into account the counterpressure during the injection process, which is missing in contrast to the aforementioned APC approach.

Among other things, a respective selection of materials, a total time of a production interruption and further codes or indices for controlling a start-up process are preferably used for a regulation of a starting process. Essentially in contrast to the frequent "APC" modules and methods of formation mentioned at the beginning, an "APC" rule in the current production process is based on a nem generated by the respective tool during the filling process back pressure. In the present case of an ejection, however, the injection molding machine is separated from the tool for spraying a respective residual material out of the plasticizing unit. Thus, known "APC" data are used in this sense in order to utilize a control of the ejection process based on a correlation of the existing "APC" data for the relevant tool on an application without a tool back pressure.

In a development of the invention, a method and a device for its implementation are able to distinguish between different "starting situations":

A1: A tool is approached for the first time, there is no data record.

This means that APC data can not be used, but APC data can be used for similar use cases. This is used for characteristic values from a database for a comparable application or material in order to achieve an improvement when starting up.

Thus, the new tool or its identifier or identification number, etc., the trigger for detecting this Anfahrsituation.

A2: A tool is re-equipped and started or restarted after a break due to an interruption. Thus, there are stored values of an APC data set from a previous production plant, on the basis of which "startup" is optimized, and a "learning phase" for determining a specific APC data record can be minimized.

Here, the interruption time is the essential feature for this starting situation.

A3: A tool is in production and it has to be restarted after a short disruption or machine stop: The APC control system optimizes the continuation of production with the key figures currently determined and available in the control system, so in principle there is no more learning phase necessary, this is essentially followed by a "standard" APC process in the injection molding machine. Thus, this Anfahrsituation is characterized in that the tool has not been changed and also an interruption of production within certain limits. These parameters are monitored by an inventive method in a corresponding device to control subsequent processes accordingly.

Advantageously, it is ensured by one or more of the features listed above that, for example, only as many Abspritz strokes are passed through until the melt reaches a predetermined actual state and thus the actual production can be restarted while saving time, energy and material ,

Furthermore, the object is also achieved by a device for controlling a starting process of an injection molding machine, which is designed to implement a method according to one of the preceding claims characterized in that the device means for using key figures from a steady state of each production process or due to process parameters comparable Has production processes, based on which a respective number of Abspritz cycles can be determined and set.

According to a development, the device comprises an APC module and a database with historical values and comparison values and is designed using parameters for selecting a controller from predefined cases of startup processes.

Further, the plasticizing unit with an integrated start-up valve downstream of the screw tip for targeted discharge of the starting material, e.g. provided directly in a collecting container and / or with a closing nozzle with a corresponding additional opening to the outside and an additional closure position. Both solutions can facilitate the discharge of no longer usable Plastilat.

Further features and advantages of embodiments according to the invention will be explained in more detail below with reference to an embodiment. In the figure, an injection molding machine 1 and a section of a tool 2 are shown symbolically. provides. The injection molding machine 1 and the tool 2 are separated in an implied manner. In this case, a situation indicative of a starting process is indicated by the fact that the injection molding machine 1 so far moved away from the tool 2 by a distance d, that in a plasticizing 3 of the injection molding machine 1 unacceptably long remaining and overheated melt than so-called Purification of a screw 4 of the plasticizing 3 must be targeted discharged. This starting material, not shown in the drawing, thus certainly does not get into the tool 2 in order to avoid possible damage or expensive cleaning of the tool 2, in particular otherwise. Important parameters here are an ejected material flow m and melt state information.

A dashed line around a part of the injection molding machine 1 indicates a range of parameters and measured variables, as used in accordance with the teaching of DE 10 2013 1 1 1 257 B3 in the context of an APC control device, in order to avoid parameter fluctuations in an ongoing production Produce good parts. Exemplary here are a speed n and a speed v of the screw 4, a mass M supplied fresh granules with a temperature d _s of fresh granules when fed into the plasticizing unit 3 and a material flow m and a temperature d _{p of} the plastilate at the output of the plasticizing. 3 specified as used parameters in non-exhaustive enumeration. This number of parameters for the APC control device is now extended in implementation of the present invention by a tool identifier W and a production interruption time At to form a device for optimizing various scenarios or predefined cases of startup processes. On the basis of the mentioned parameters, key figures of the respective production process and, if necessary, also compared with those of similar production processes are obtained in order to determine and set a respective number of injection cycles

Scenarios or predefined cases are in this embodiment in detail:

1 . Restarting after production stop: By measuring the production interruption time At, the device recognizes a continuation of one and ongoing production and takes a database DB appropriate measures to protect the tool in question from damage caused by now unusable, in the plasticizing unit 3 adjacent melt. In accordance with a possible degeneration of the melted material, the control now causes the melted product to be discharged while tracking freshly melted granules until the plasticizing unit 3 has been sufficiently cleaned. This process, which is dependent on a respective plasticizing unit 3 and a material used in terms of time and material volume, is likewise determined on the basis of values from the database.

2. Tool exchange: Based on a modified tool identifier W, the device detects a tool exchange. A new tool identifier W is transmitted to the database DB, there either APC values of a previous manufacturing process or APC values of a similar tool. Taking into account a production interruption time Δt, a startup process is now controlled and monitored on the basis of these values.

3. Resumption of Production: Here, the values for a production interruption time Δt show too high values, or in the course of a tool change, a known tool is used again on the injection molding machine 1 on the basis of a specific tool identifier W. Depending on the particular situation, this case is a variant of one or both of the above scenarios, so that a start-up process is controlled accordingly.

In a not further illustrated embodiment, the plasticizing unit 3 is provided with an integrated start-up valve downstream of the screw tip for targeted discharge of the Anfahrmaterials eg directly into a collecting container, analogous to a starting valve at IMC. An essential aim of this development is that the starting material can be disposed of directly without causing further break times for removing the material, for example, from the nozzle protection space. This goal can alternatively be achieved by a closure nozzle with a corresponding additional opening to the outside and an additional closure position. Both constructive measures described above facilitate a discharge of no longer usable plastilate from the plasticizing unit 3 and thus speed up and simplify a start-up process.

Injection molding machine

Tool

plasticizing

slug

APC APC control unit

d way

DB database

m Mate alstrom

n speed of the screw 4

Production interruption time

v Speed of the screw 4

W tool identifier

d _p temperature of the plastilate

d _s temperature of the fresh granules when fed into the plasticizing unit 3

M mass supplied granules

Claims

claims

1 . Method for controlling a start-up process of a Sphtzgießmaschine,

characterized,

that use of key figures from a steady state of a respective production process is performed in order to determine and set a respective number of Abspritz cycles.

2. Method according to the preceding claim, characterized in that the key figures of the respective production process are also obtained by comparison with those of similar production processes, wherein a similar production process with regard to the specific properties, i.a. a pairing of a respective tool and a used injection molding machine, is determined.

3. The method according to any one of the preceding claims, characterized in that the key figures are obtained using key figures from an "APC" module and / or using a database (DB).

4. The method according to any one of the preceding claims, characterized in that the control is carried out using so-called melt state information of the plasticizing unit (3).

5. The method according to any one of the preceding claims, characterized in that the control using certain parameters (W, At) between at least two predefined cases of starting processes differs to optimize a respective starting process.

6. Device for controlling a starting process of an injection molding machine, characterized in that it is designed to implement a method according to one of the preceding claims characterized in that the device comprises means for using key figures from a steady state of a respective production process or process parameters due to has comparable production processes, based on which a respective number of Abspritz cycles can be determined and set.

7. Device according to the preceding claim, characterized in that the device comprises an APC module and a database (DB) with historical values and comparison values and using parameters (W, At) to select a controller from predefined cases of startup processes is.

8. Device according to one of the preceding claims, characterized in that the plasticizing unit (3) with an integrated start-up valve downstream of the screw tip for targeted discharge of the starting material, e.g. is provided directly in a collecting container.

9. Device according to one of the preceding claims 6 to 8, characterized in that the plasticizing unit (3) has a closure nozzle with a corresponding additional opening to the outside and an additional closure position.