Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/76—Measuring, controlling or regulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
  • B29C2945/76—Measuring, controlling or regulating
  • B29C2945/76929—Controlling method
  • B29C2945/76993—Remote, e.g. LAN, wireless LAN
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
  • G05B2219/00—Program-control systems
  • G05B2219/30—Nc systems
  • G05B2219/45—Nc applications
  • G05B2219/45244—Injection molding

Definitions

• the present invention relates to a control system for remote monitoring of machines for injection moulding of plastic material products.
• the present invention relates to a control system able to remote survey a number of machines for injection moulding of plastic material products, in which the various machines are divided into groups designed to produce one and the same plastic product, and in which each group of machines comprises a plurality of injection-moulding machines different from one another and located at a great distance from one another.
• machines for injection moulding of plastic material products are usually made up of : a piece-forming the die generally comprising at least two metal bodies designed to be cyclically brought up one against the other, and structured so as to form, on the contact surface between them, a closed mould shaped so as to reproduce in negative the shape of the plastic product to be formed; a bodies-moving press structured so as to bring the two metal bodies that form the die cyclically one against the other, so to cyclically form the mould that reproduces in negative the shape of the product to be formed; and a plasticizing unit which receives at input a more or less continuous flow of granular plastic material, and is able to liquefy the plastic material and then feed a continuous flow of said material in the liquid or semisolid state directly into the piece- forming die with a pre-set pressure .
• the piece-forming die is provided with a liquid-state plastic-material injection device, traditionally referred to as "hot-runner device", which is stably fixed on one of the two metal bodies of the die, and is designed to feed in a controlled manner the liquid-state plastic material into the closed mould formed by coupling together the two metal bodies, and the machine plasticizing unit is designed to feed a continuous flow of plastic material in the liquid or semisolid state directly to the hot- runner device.
• hot-runner device a liquid-state plastic-material injection device
• the hot-runner device is housed in a seat provided on one of the two metal bodies of the die, and is basically formed by: a hollow metal body, traditionally referred to as "hot chamber” , designed to be filled up with liquid-state plastic material by the plasticizing unit; a number of injectors, which branch off from the hot chamber up to reach the mould located at the centre of the two metal bodies, and are structured so as to regulate the outflow of the liquid plastic material towards the mould at the centre thereof; and finally a number of electrically supplied heating units, which are appropriately distributed along the body of the hot -runner device formed by the hot chamber and by the various injectors, so to be able to heat, by Joule effect, the plastic material present inside said hot-runner device.
• a hollow metal body traditionally referred to as "hot chamber”
• injectors which branch off from the hot chamber up to reach the mould located at the centre of the two metal bodies, and are structured so as to regulate the outflow of the liquid plastic material towards the mould at the centre thereof
• electrically supplied heating units which
• Each heating unit is formed by at least one resistor appropriately positioned in the body of the hot -runner device, and by a corresponding thermocouple which is located in the immediate vicinity of the resistor so as to be able to measure in real time the temperature value of the portion of the hot- runner device around said resistor.
• Said temperature value obviously depends directly upon the amount of heat that is produced via Joule effect by the resistor and is then transmitted directly to the body of the hot-runner device and to the plastic material contained therein. In fact, as long as it remains inside the hot -runner device, the plastic material must be kept always in the liquid or semisolid state.
• Machines for injection moulding of plastic material products are finally provided with a die electronic control unit which is connected to the thermocouples of the various heating units, and is able to independently supply electric energy to each of the resistors of the various heating units in such a way that each resistor present in the hot-runner device will be supplied, instant by instant, with an electric power enough to keep the temperature of the portion of the hot-runner device around the resistor itself at a specific reference value purposely stored inside the control unit itself.
• the electronic control unit is designed also to drive the individual injectors that branch off from the hot chamber so as to cause the plastic material to come out in the liquid state from each injector according to a pre-set timing, stored inside the control unit itself.
• the much more sophisticated and costly electronic control units moreover, integrate inside them a data-processing module which is able to continuously monitor the time evolution of the temperatures measured by the various thermocouples and of the powers supplied by the individual resistors, so as to be able to detect, via purposely provided algorithms of statistical analysis, the onset of any possible malfunctioning in the hot-runner device and/or small losses of plastic material from the latter, with consequent signalling of the problem and possibly immediate arrest of the machine.
• the mechanical characteristics and ageing resistance of the plastic product depend upon the machine that has formed the product .
• the production quality of the plastic components and their immediate availability along the assembly line are production requirements of fundamental importance for proper operation of a production plant. For this reason, automobile manufacturers are forced to employ vast resources for planning and monitoring provisioning of plastic components according to the production trend in the production plant, and for verifying with sample tests the quality of the individual lots of plastic components that are supplied by the various suppliers .
• each plastic-components supplier subjects the plastic products that come out of its own dies, to a quality control having the sole purpose of identifying and eliminating the pieces that present evident structural defects .
• the aim of the present invention is to provide a control system that is able to monitor the operation of a number of machines for injection moulding of plastic material products, irrespective of the geographical location of the individual machines, so as to enable, in real time, an integrated control of the production quality of each individual plastic material component, irrespective of the lot to which it belongs and of the supplier.
• a control system for remote monitoring of machines for injection moulding of plastic material products is provided as specified in Claim 1 and, preferably, in any one of the subsequent claims depending either directly or indirectly upon Claim 1.
• FIG. 1 is a schematic view of a control system for remote monitoring of machines for injection moulding of plastic material products provided according to the teachings of the present invention
• - Figure 2 is a schematic illustration, with parts removed for clarity, of a machine for injection moulding of plastic material products and of other components of the Figure 1 control system.
• number 1 designated as a whole a control system designed to enable a generic operator to remote survey a number of machines 2 for injection moulding of plastic material products, irrespective of the geographical location of the individual machines 2, via a remote- surveillance electronic processor 3 which is connected, via a data-transmission network of a known type (for example, the Internet), to each of the aforesaid machines 2 for injection moulding of plastic products.
• a remote- surveillance electronic processor 3 which is connected, via a data-transmission network of a known type (for example, the Internet), to each of the aforesaid machines 2 for injection moulding of plastic products.
• each of the machines 2 for injection moulding of plastic products is basically formed by: a piece-forming die 4 which comprises at least two preferably, though not necessarily, parallelepiped-shaped metal bodies 5 which are designed to be brought one against the other and are shaped so as to form, at the centre of the contact surface between the bodies, a closed mould 5a reproducing in negative the shape of the plastic material product to be formed; a bodies-moving press 6 - preferably, though not necessarily, of hydraulically operated type - which supports the two metal bodies 5 and is structured so to be able to bring, on command, the two metal bodies 5 one against the other so as to form mould 5a; and a plasticizing unit 7 which is designed to receive at input a more or less continuous flow of granular plastic material, to liquefy the aforesaid granular plastic material, and finally to feed in a controlled manner the liquid-state plastic material into die 4, with a pre-set pressure .
• the piece- forming die 4 is provided with a liquid-state plastic-material injection device 8, traditionally referred to as "hot-runner device", which is designed to feed in a controlled manner the liquid-state plastic material up to mould 5a at the centre of the two metal bodies 5, and the plasticizing unit 7 is designed to feed a continuous flow of the liquid or semisolid state plastic material into injection device 8.
• a liquid-state plastic-material injection device 8 traditionally referred to as "hot-runner device”
• the plasticizing unit 7 is designed to feed a continuous flow of the liquid or semisolid state plastic material into injection device 8.
• the liquid-state plastic-material injection device 8 is housed in a seat provided on one of the two metal bodies 5 of die 4 and is basically formed by: a hollow metal body 9, traditionally referred to as "hot chamber” , which is designed to be filled with liquid state plastic material; one or more injectors 10, which branch off from the hollow metal body 9 up to reach the part of mould 5a realized on the same metal body 5, and are structured so as to regulate the outflow of the liquid plastic material towards said mould 5a; and finally a number of electrically supplied heating units (not illustrated) , which are appropriately distributed along the injection device 8 body formed by hollow metal body 9 and by the various injectors 10, so as to be able to heat, via Joule effect, the plastic material present inside the injection device 8.
• a hollow metal body 9 traditionally referred to as "hot chamber”
• injectors 10 which branch off from the hollow metal body 9 up to reach the part of mould 5a realized on the same metal body 5, and are structured so as to regulate the outflow of the liquid plastic material towards said mould 5a
• each heating unit comprises at least one resistor (not illustrated) positioned in the body of the injection device 8, and at least one thermocouple (not illustrated) or some other temperature sensor, which is located in the immediate vicinity of the aforesaid resistor in so to be able to measure, in real time, the temperature value of the portion of injection device 8 around the resistor itself.
• each machine 2 for injection moulding of plastic material products is finally provided with: an electric-supply unit (not illustrated) which, on command, is able to independently supply electric energy to each of the resistors of the various heating units (not illustrated) ; and a local die electronic control unit 11 which is directly connected to the electric -supply unit and to the injection device 8, and is able to drive the electric-supply unit as a function of the signals coming from the aforesaid injection device 8.
• electronic control unit 11 is preferably, though not necessarily, positioned on the outside of the protective casing that encloses the press 6, the die 4, and possibly the plasticizing unit 7 of the machine 2, at a short distance from the die 4 (generally not more than 3-4 meters) ; it is directly connected to the electric-supply unit, to the thermocouples of the various heating units, and to the injectors 10; and it is finally able to drive the electric- supply unit as a function of the signals coming from the individual thermocouples so that each resistor present in the injection device 8 will be supplied, instant by instant, with an electric power enough to keep the temperature of the portion of the injection device 8 around the resistor itself at a pre-set reference value that is exclusively associated to said resistor, or rather to the portion of the injection device 8 around said resistor, and that is stored inside the electronic control unit 11 itself.
• electronic control unit 11 is designed also to drive the individual injectors 10 of the injection device 8 so to let the liquid- state plastic material to come out in a controlled manner from each injector 10 according to a pre-set timing, appropriately stored inside the electronic control unit 11 itself.
• electronic control unit 11 also comprises a data-processing module (not shown) , which is able to continuously monitor the time evolution of the temperatures measured by the various thermocouples and of the powers supplied by the individual resistors so as to be able to detect, via purposely provided algorithms of statistical analysis, the onset of any possible malfunctioning in the injection device 8 and/or of minor leakage of plastic material from the latter, with consequent signalling of the problem and immediate arrest of the machine 2.
• a data-processing module (not shown) , which is able to continuously monitor the time evolution of the temperatures measured by the various thermocouples and of the powers supplied by the individual resistors so as to be able to detect, via purposely provided algorithms of statistical analysis, the onset of any possible malfunctioning in the injection device 8 and/or of minor leakage of plastic material from the latter, with consequent signalling of the problem and immediate arrest of the machine 2.
• electronic control unit 11 of each machine 2 of the system is provided with a data- transmission module 12 which is connected, via a data-transmission network 13 of a known
• electronic processor 3 it is able to receive from the various electronic control units 11 values or time evolutions of all the process physical quantities processed by the control units during each individual injection cycle, and then verify whether the actual values or time evolutions of the process physical quantities processed by each electronic control unit 11 during each injection cycle remain within pre-set tolerance limits with respect to standard values or time evolutions of the same process physical quantities, which are specific for the plastic material product produced by the die 4 to which the electronic control unit 11 is currently connected. Said standard time evolutions are obviously stored within the electronic processor 3.
• electronic processor 3 stores within itself the standard values or time evolutions of all the process physical quantities taken into account by the generic electronic control unit during the injection cycle of each plastic product that can be produced by the machines 2 of the system, and the maximum tolerance limits associated to each physical quantity processed by the control unit for each plastic product that can be formed by the machines 2 of the system; and it is able to compare, at the end of each injection cycle, the actual time evolutions of the process physical quantities processed by each electronic control unit 11 with the standard time evolutions associated to the plastic product formed by the die 4 to which said electronic control unit 11 is currently connected, so as to identify those electronic control units 11 that present actual time evolutions of the process physical quantities that depart from the corresponding standard time evolutions beyond the pre-set tolerance limits.
• each electronic control unit 11 is able to govern only one piece -forming die 4 at a time, when electronic processor 3 identifies an electronic control unit 11 that presents time evolutions of the process physical quantities that departs excessively from the standard ones, it also identifies a machine 2 for injection moulding of plastic products, which is not performing, at the moment, an optimal plastic material injection process and which could produce a number of plastic products to be rejected because manifestly faulty (hence causing considerable delays in provisioning of that specific component) , or else a number of plastic products presenting mechanical characteristics and/or an ageing resistance considerably departing from those envisaged in the design stage .
• remote-surveillance electronic processor 3 is formed by: a main server 14 which is directly connected to the data- transmission network 13 so as to receive at input the data coming from the data-transmission module 12 of the electronic control unit 11 of die 4 of each machine 2; and at least one auxiliary command and control terminal 15, via which the operator can command and interact with the server 14 for surveying in real time the production activity of each individual type of plastic product produced by the machines 2.
• server 14 can moreover signal to the operator the possible electronic control units 11 that present actual time evolutions of the process physical quantities that depart from the corresponding standard time evolutions beyond the pre-set tolerance limits, i.e. the possible machines 2 that are not performing an optimal plastic material injection process and that could produce a number of faulty plastic products, or else ones that are not in line with the design requirements .
• the server 14 can moreover be programmed so to group together the operating data received from the various electronic control units 11 in a series of homogeneous production groups, each of which comprises the operating data of the control electronics 11 of all the machines 2 that are producing one and the same type of plastic product, irrespective of the geographical location of the individual machines 2.
• Said possibility enables the operator to survey in real time and with extreme ease the production general evolution of each individual type of plastic product produced by the machines 2, irrespective of the geographical location of the individual machines 2, offering the possibility of tracing back to the individual electronic control unit or units 11 that presents or present the actual time evolutions of the process physical quantities that depart excessively from the standard ones, only when operating faults are detected.
• the terminal 15 can in fact be provided with an appropriate object -graphic interface, which enables the operator to access the operating data stored inside server 14, via a series of icons, each of which is associated in a unique way to just one type of plastic product or component.
• terminal 15 may also be able to query the server 14 to supply the operator with a set of information necessary for identifying each machine 2, irrespective of the production group to which it belongs, and/or additional information such as, for example, the type of product currently produced by each individual machine 2, and/or the geographical location of the machine 2, and/or the name of the supplier that is the owner or user of the machine 2.
• the electronic control unit 11 of each machine 2 is preferably, though not necessarily, provided also with a recognition module 16 which, by analysing the signals exchanged between the control unit and the die 4, is able to identify the die 4 currently connected to the electronic control unit 11, and to communicate to electronic processor 3 the identity of the piece -forming die 4 currently connected to the control unit itself.
• electronic processor 3 is able to associate the time evolutions of the process physical quantities directly to each piece-forming die 4 so to directly monitor the operation of each individual piece- forming die 4, irrespective of its geographical location.
• die 4 is provided with a memory module 20 which contains inside itself a set of data designed to enable recognition of said die 4. More specifically, the information stored in memory module 20 can comprise, for example, an identification code uniquely associated to die 4, and/or a production parameter indicating the total number of products formed by die 4 during its use, and/or a series of indications on maintenance operations to which the die 4 has been subjected during its use, and/or a series of moulding parameters characterizing the die 4.
• the memory module 20 is configured so to enable the recognition module 16 of the electronic control unit 11 to access the data contained inside it, and to transmit them to the server 14 so to enable identification of die 4 via processing of the identification code.
• memory module 20 can be constituted, for example, by a transponder of passive or active type, which is structured so as to be able to store the aforementioned data, and is able to perform a wireless communication with the electronic control unit 11.
• the memory module 20 may moreover be able to perform a data communication, for example, a wireless communication, also with auxiliary reading apparatuses, such as, for example, portable recognition apparatuses 21 (only one of which is shown in Figure 2) , enabling the latter to identify the die 4 even when it is being separate from the machine 2 and/or disconnected from the electronic control unit 11.
• a data communication for example, a wireless communication
• auxiliary reading apparatuses such as, for example, portable recognition apparatuses 21 (only one of which is shown in Figure 2) , enabling the latter to identify the die 4 even when it is being separate from the machine 2 and/or disconnected from the electronic control unit 11.
• the portable recognition apparatus 21 performs a "local" reading, i.e., a reading at a short distance, of the data contained in the memory module 20 so as to remotely transmit them to server 14 via the data- transmission network 13, allowing server 14 to process the identification code to recognize the die 4, communicate to the portable recognition apparatuses 21 the information on the die 4, and possibly update the information on the die 4 contained inside it when the latter differs from the information communicated in the course of data transmission.
• a "local" reading i.e., a reading at a short distance
• the memory module 20 can be replaced by a bar code applied on the die 4, with the obvious modifications to the portable recognition apparatus 21.
• server 14 may also be able to process the operating data received from the various electronic control units 11 so as to establish the degree of efficiency of each machine 2, assigning to each machine a class of production efficiency correlated to the percentage of injection cycles over the total that present actual values or time evolutions of the process physical quantities that depart from the corresponding standard time evolutions beyond the pre-set tolerance limit.
• terminal 15 can be programmed so to enable the operator to view, instant by instant, the class of efficiency of all the machines 2 of the entire control system 1, or else only of the machines 2 that belong to an individual production group so as to assess the efficiency of the production cycle of each individual type of plastic product formed by the machines 2 included in the control system 1.
• the server 14 may also be able to process the operating data received from the various electronic control units 11 so to assign to each machine 2 the corresponding class of efficiency by processing with statistical criteria also the deviation amount between the actual values or time evolutions of the process physical quantities acquired during the injection cycle and the standard values or time evolutions associated to the product.
• server 14 may be able to detect and automatically signal to the operator when there arise critical conditions of provisioning of any one of the various types of plastic products formed by the machines 2 of the system.
• server 14 can carry out a systematic control of the production capacity of the machines 2 belonging to each production group, detecting when the effective production capacity of the product drops below a pre-set limit value. Limit value that could create subsequently problems of component provisioning.
• server 14 could also perform a predictive statistical check to identify the likely number of products produced by the machines 2 of each production group, resizing the nominal production capacity of each machine 2 of the current production group according to the production efficiency class assigned to the machine 2 itself.
• server 14 could also be able to supply, for each die 4, information on the number and/or quality of the products produced via the die 4 during its use, and/or information on the use status of the die 4, which could correspond to a maintenance status, or to a temporary stoppage status, or an active production status.
• auxiliary terminal or terminals 15 it or they may be able to access server 14 through a local connection and/or through a remote connection via the data- transmission network 13.
• server 14 and consequently all the data processed thereby can be conveniently accessible, either from one "local” auxiliary- terminal 15 or from one or more "remote” auxiliary terminals.
• control system 1 Operation of the control system 1 described may be readily deduced from what has been set forth above, and hence does not require any further explanation.
• control system 1 for remote monitoring of machines for injection moulding of plastic products affords numerous advantages.
• the control system 1 described above enables simultaneous surveillance of the production activities of all suppliers, concentrating each time on the critical situations that arise with the individual suppliers, delegating to electronic processor 3 the task of surveying instant by instant the activity of each individual machine 2 or die 4 of each plastic-components supplier entered in the control system 1, signalling in due time both the conditions of non-optimal execution of the injection process and the possible provisioning problems of the individual plastic components. Said timely signalling enables the operator to pre-arrange in due time adequate countermeasures .
• control system 1 for monitoring machines for injection moulding of plastic material products described above, without thereby departing from the scope of the present invention.
• the data- transmission module 12 can send continuously to the electronic processor 3 the values or the time evolutions of only part of the process physical quantities acquired and/or processed by the electronic control unit 11 during each individual injection cycle.
• each electronic control unit 11 can be provided with an auxiliary data-processing module that performs a part of the calculation made by server 14.
• each electronic control unit 11 instead of transmitting indistinctly to server 14 all the actual time evolutions of the physical quantities monitored, can perform directly within it a comparison of the actual time evolutions of all or part of the physical quantities acquired during the moulding cycle, with the corresponding standard time evolutions associated to the plastic product formed by the die 4, so to discriminate the actual time evolutions of the physical process quantities that depart from the corresponding standard time evolutions beyond the pre-set tolerance limits.
• electronic control unit 11 detects an excessive deviation only of some physical quantities (for example, an excessive deviation of just the temperature of a portion of the hot chamber 9) , it transmits to the server 14 only the evolutions of the physical process quantities that depart excessively from the standard ones, signalling at the same time that the other physical quantities monitored fall within the pre-set tolerance limits.
• electronic control unit 11 performs a preliminary check on the process physical quantities, and simply transmits to the server 14 the time evolutions or values of the process physical quantities that are not under its direct control, and the time evolutions or values of the process physical quantities that depart excessively from the corresponding standard time evolutions or values.
• electronic control unit 11 can simply communicate to server 14 whether the process physical quantities monitored thereby depart or not from the corresponding standard time evolutions or values, consequently excluding from the data transmission to server 14 the actual measured time evolutions or values of all the physical quantities monitored by said control unit.
• the surveillance electronic processor 3 is configured as a calculation system of a "distributed" type, in which the auxiliary data-processing modules of the individual electronic control units 11 carry out a preprocessing of all or part of the process physical quantities managed by the control system 1 so to be able to discriminate in situ the process physical quantities the detected evolutions or values of which are "useful" for remote surveillance of the production activities of the various machines 2 for injection moulding of plastic products.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)

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Cited By (6)

Citations (4)

• 2007
  • 2007-10-23 IT ITTO20070133 patent/ITTO20070133U1/it unknown
• 2008
  • 2008-10-22 WO PCT/IB2008/002818 patent/WO2009053817A1/en active Application Filing

Patent Citations (4)

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