METHOD AND DEVICE FOR CLASSIFY AT LEAST ONE TEMPERATURE CONTROL BRANCH

Abstract

A method of classifying a temperature control branch of a molding toolincludes producing molded parts in cycles by a portion of the molding tool by introducing heat into the molding tool, and/or cyclically activating a heating device, with introduction of heat into the molding tool, conveying temperature control medium through the temperature control branch of the molding tool to dissipate the introduced heat, measuring a temporal branch temperature profile of the temperature control medium in the temperature control branch over several production cycles, analyzing a curve behavior of the branch temperature profile and/or of a variable derived from the branch temperature profile, in particular of a branch heat flow, over several production cycles, and sorting the temperature control branch into one of at least two categories, according to greater and/or smaller influence on the heat budget of the portion of the molding tool, on the basis of the curve behavior.

Claims

1. A method for classifying at least one temperature control branch of a molding took according to an influence on a heat budget of at least one portion of the molding tool wherein the following method steps are performed: producing, by proceeding in production cycles, molded parts by means of the at least one portion of the molding tool, with introduction of heat into the molding tool, and/or cyclically activating a heating device, with introduction of heat into the molding tool, conveying temperature control medium through the at least one temperature control branch of the molding tool in order to dissipate at least some of the introduced heat, measuring at least one temporal branch temperature profile of the temperature control medium in the at least one temperature control branch over several production cycles, analyzing a curve behavior of the at least one branch temperature profile and/or of a variable derived from the at least one branch temperature profile, in particular of at least one branch heat flow, over several production cycles, and sorting the at least one temperature control branch into one of at least two categories, according to greater and/or smaller influence on the heat budget of the at least one portion of the molding tool, on the basis of the curve behavior.

2. The method according to claim 1, wherein analysis of the curve behavior includes or is an analysis of the oscillation behavior.

3. The method according to claim 2, wherein, for the dissipation of at least some of the introduced heat, temperature control medium is conveyed through temperature control branches of the molding tool, temporal branch temperature profiles of the temperature control medium in the temperature control branches are measured over several production cycles, which branch temperature profiles are subject to different fluctuations owing to different degrees and/or rates of heat transfer of the heat introduced into the molding tool to the respective temperature control branch, differences occurring in the oscillation behavior between the branch temperature profiles and/or the variable, derived from the at least one branch temperature profile, of the temperature control branches are identified, and the temperature control branches are sorted into in each case one of the at least two categories, according to greater and/or smaller influence on the heat budget of the at least one portion of the molding tool, on the basis of the differences in the oscillation behavior.

4. The method according to claim 2, wherein, within the framework of the analysis of the oscillation behavior, an amplitude, a frequency and/or a period of the at least one branch temperature profile and/or of the variable derived therefrom is determined, and is optionally used for the identification of the differences in the oscillation behavior.

5. The method according to claim 1, wherein the analysis of the curve behavior includes or is an analysis of the increase or decrease behavior.

6. The method according to claim 5, wherein, for the dissipation of at least some of the introduced heat, temperature control medium is conveyed through temperature control branches of the molding tool, temporal branch temperature profiles of the temperature control medium in the temperature control branches are measured, which branch temperature profiles are subject to different fluctuations owing to different degrees and/or rates of heat transfer of the heat introduced into the molding tool to the respective temperature control branch, differences occurring in the increase or decrease behavior between the branch temperature profiles and/or the variable, derived from the at least one branch temperature profile, of the temperature control branches are identified, and the temperature control branches are sorted into in each case one of the at least two categories, according to greater and/or smaller influence on the heat budget of the at least one portion of the molding tool, on the basis of the differences in the increase or decrease behavior.

7. The method according to claim 5, wherein, within the framework of the analysis of the increase behavior, a time of the first increase of the at least one branch temperature profile lying above a threshold value is determined, and is optionally used for the identification of the differences in the increase behavior.

8. The method according to claim 1, wherein at least one setpoint value for the open-loop or closed-loop control of temperature control media flow conveyed through the at least one temperature control branch is set on the basis of the category of the at least one temperature control branch.

9. The method according to claim 8, wherein at least one setpoint temperature difference between an inlet temperature and an outlet temperature of the at least one temperature control branch is used as at least one setpoint value, wherein the setpoint temperature differences for temperature control branches with greater influence on the heat budget of the at least one portion of the molding tool are preferably set smaller in magnitude than the setpoint temperature differences for temperature control branches with smaller influence on the heat budget of the at least one portion of the molding tool.

10. The method according to claim 8, wherein at least one setpoint volume flow is used as at least one setpoint value, wherein the setpoint volume flows for temperature control branches with greater influence on the heat budget of the at least one portion of the molding tool are preferably chosen to be larger, relative to a maximum achievable volume flow, than in the case of temperature control branches with smaller influence on the heat budget of the at least one portion of the molding tool.

11. The method according to claim 1, wherein actuators for open-loop-controlled or closed-loop-controlled influencing of temperature control media flow conveyed through the at least one temperature control branch are made equal, in particular are fully opened, at the start of the method.

12. The method according to claim 1, wherein several temperature control branches are used, and the actuators for open-loop-controlled or closed-loop-controlled influencing of temperature control media flows conveyed through the temperature control branches are adjusted at the start of the method such that the temperature control media flows through the temperature control branches are made equal.

13. The method according to claim 1, wherein the at least one branch temperature profile is used in the form of a temporal profile of at least one temperature difference between an inlet temperature and an outlet temperature of the at least one temperature control branch.

14. The method according to claim 1, wherein the at least one temperature control branch is sorted into one of at least three categories, which at least three categories include at least one category of great influence on the heat budget of the portion of the molding tool, at least one category of medium influence on the heat budget of the portion of the molding tool and at least one category of small influence on the heat budget of the portion of the molding tool.

15. The method according to claim 1, wherein at least one of the method steps of the method according to one of the preceding claims is performed automatically by a processing unit.

16. A temperature control device for the temperature control of a molding tool, in particular configured to perform the method according to claim 1, with a conveying device for conveying temperature control medium through at least one temperature control branch of the molding tool, a processing unit, and at least one temperature sensor which is connected, for transmission of signals, to the processing unit and which is configured to measure at least one temporal branch temperature profile of the temperature control medium in the at least one temperature control branch, characterized in that the processing unit-(5) is configured to perform an analysis of a curve behavior, preferably of an increase or decrease behavior and/or of an oscillation behavior, of the at least one branch temperature profile and/or of a variable derived from the at least one branch temperature profile, in particular of at least one branch heat flow, preferably over several production cycles, and to sort the at least one temperature control branch into one of at least two categories, according to greater and/or smaller influence on the heat budget of at least one portion (3) of the molding tool, on the basis of the curve behavior, preferably of the increase or decrease behavior and/or of the oscillation behavior.

17. The temperature control device according to claim 16, wherein several temperature control branches and several temperature sensors are provided, and the processing unit is formed to identify differences occurring in the oscillation behavior and/or in the increase or decrease behavior between the branch temperature profiles of the temperature control branches and to sort the temperature control branches into in each case one of the at least two categories, according to greater and/or smaller influence on the heat budget of at least one portion of the molding tool, on the basis of the identified differences in the increase or decrease behavior and/or in the oscillation behavior.

18. A forming machine with the temperature control device according to claim 16, wherein the forming machine is preferably formed for producing molded parts in forming cycles.

19. A computer program product for classifying at least one temperature control branch of a molding tool according to an influence on a heat budget of at least one portion of the molding tool, in particular for performing the method according to claim 1, with instructions which cause an executing computer to receive measured values in the form of at least one temporal branch temperature profile of a temperature control medium conveyed through at least one temperature control branch of the molding tool, wherein the measured values are preferably present over several production cycles, to perform an analysis of a curve behavior, preferably of an increase or decrease behavior and/or of an oscillation behavior, of the at least one branch temperature profile and/or of a variable derived from the at least one branch temperature profile, in particular of at least one branch heat flow, preferably over several production cycles, and to sort the at least one temperature control branch into one of at least two categories, according to greater and/or smaller influence on the heat budget of the at least one portion of the molding tool, on the basis of the curve behavior, preferably of the increase or decrease behavior and/or of the oscillation behavior.

20. The computer program product according to claim 19, wherein the instructions cause the executing computer to receive the measured values in the form of branch temperature profiles of the temperature control medium conveyed through temperature control branches of the molding tool, which branch temperature profiles are subject to different fluctuations owing to different degrees and/or rates of heat transfer of heat introduced into the molding tool to the respective temperature control branch, to identify differences occurring in the oscillation behavior and/or in the increase or decrease behavior between the branch temperature profiles of the temperature control branches, and to sort the temperature control branches into in each case one of the at least two categories, according to greater and/or smaller influence on the heat budget of the at least one portion of the molding tool, on the basis of the identified differences in the increase or decrease behavior and/or in the oscillation behavior.

21. A computer-readable storage medium on which a computer program product according to claim 19 is stored.

Description

[0127] Further details and advantages of the invention follow from the figures and from the associated description of the figures. There are shown in:

[0128] FIG. 1 a schematic representation of a molding tool,

[0129] FIG. 2 a traced photographic representation of a molding tool (image source: Wikipedia),

[0130] FIG. 3 examples of branch temperature profiles for performing the method according to the invention,

[0131] FIG. 4 Fourier transformation of the branch temperature profiles,

[0132] FIG. 5 a diagram to explain the sorting according to the invention of the temperature control branches into categories,

[0133] FIG. 6 the representation of the molding tool from FIG. 2, wherein it has been marked which temperature control branches have what influence on the heat budget of the molding tool,

[0134] FIG. 7 a diagram to illustrate the principle, utilized by the invention, of the propagation of thermal waves (image source: Plastverarbeiter [German-language plastics-processing industry journal])

[0135] FIG. 8 a schematic representation of the arrangement according to the invention together with a temperature control device according to the invention, and

[0136] FIG. 9 a schematic representation of a molding tool with a hot runner system (image source: Plastverarbeiter).

[0137] FIG. 1 shows a schematic representation of a molding tool 2 (here the nozzle side of an injection molding tool) in which the method according to the invention has been performed. Temperature control branches (temperature control circuits) K1 to K4 and KX and KY lead through the molding tool 2. In this design, the temperature control branches K1 to K4 and KX and KY are connected in parallel in the fluidic sense (analogously to FIG. 8).

[0138] However, for the sake of simplicity, only the temperature control branches K1 to K4 have been used for the method according to the invention in order to reduce the amount of data.

[0139] It is to be noted that the temperature control branches K1 to K4 are not represented according to their actual spatial configuration. However, the mold cavity 13, not represented in FIG. 1, is situated approximately centrally in the molding tool 2 (indicated by the gray circle in the center).

[0140] To illustrate the functioning of the invention, temperature probes 11 (here: thermocouples) have also been installed in the molding tool 2 itself in order to demonstrate the good correlation between the actual heat situation in the molding tool 2 and the data collected according to the invention. The temperature probes 11 are more specifically numbered consecutively as H8x, H9x and H10x. Of course, these temperature probes 11 installed in the molding tool 2 are not necessarily required in practice when the method according to the invention is actually performed.

[0141] For the sake of completeness, a simplified heat balance in the injection molding tool may be expressed as follows:

{dot over (Q)}.sub.TM−{dot over (Q)}.sub.U+{dot over (Q)}.sub.F+{dot over (Q)}.sub.H=0

{dot over (Q)}.sub.TM heat flow which the temperature control medium supplies or discharges (heating or cooling by means of the temperature control medium)
{dot over (Q)}.sub.U heat flow to the surroundings
{dot over (Q)}.sub.F heat flow of the molded part
{dot over (Q)}.sub.H additional heat flow, for example through hot runners

[0142] Simplified heat flow of the molded part:

[00001]${\stackrel{.}{Q}}_F=\Delta h.Math.\frac{m_F}{t_z}$

Δh enthalpy difference
m.sub.F mass of the molded part
t.sub.z cycle time

[0143] Heat flow of the temperature control medium (in the case of cooling Q.sub.TM is negative):

{dot over (Q)}.sub.TM=−{dot over (Q)}.sub.F−{dot over (Q)}.sub.H+{dot over (Q)}.sub.U

[0144] The magnitude of the branch heat flows is represented in each case in the figures.

{dot over (Q)}.sub.TM={dot over (m)}.sub.TM.Math.c.sub.TM.Math.ΔT={dot over (V)}.sub.TM.Math.ρ.sub.TM.Math.C.sub.TM.Math.ΔT

ΔT=T.sub.in−T.sub.out

{dot over (V)}.sub.TM volume flow of the temperature control medium
ρ.sub.TM density of the temperature control medium (approximately constant in the case of a substantially constant temperature)
c.sub.TM specific heat capacity of the temperature control medium (approximately constant in the case of a substantially constant temperature)
ΔT difference between inlet and outlet temperature of a temperature control branch

[0145] The information as to which temperature control branch K1 to K4 in an actual molding tool 2 is arranged how geometrically, in particular how closely the individual temperature control branches K1 to K4 lead past the mold cavity 13, is often not available in practice. In fact, for a person responsible for setting up the forming process, the situation on the molding tool 2 appears simply as in the photograph from FIG. 2.

[0146] As depicted in the photograph, although hoses can be connected for the supply and discharge of temperature control medium (water in this embodiment example), it is not clear how these temperature control branches K1 to K4 lead through the molding tool 2.

[0147] At this point the method according to the invention can be used. Firstly, in the embodiment example presented here, the production of the molded parts is started. Since this embodiment example is an injection molding process, the production proceeds in production cycles, wherein the molding tool 2 is closed and subjected to a closing force, and a molding compound 12 (here: plastic) is then injected into the mold cavity 13.

[0148] Within the framework of the method according to the invention, the production cycles can be test cycles or start-up cycles in order to check and/or adapt the correct adjustment of the forming machine or to create defined thermal conditions. In many cases, such test cycles have to be performed during the setup of the molding tool 2 in any case.

[0149] Conveying of temperature control medium through the temperature control branches K1 to K4 is thus commenced before the start of the production cycles. Branch temperature profiles RLT01 to RLT04 of the temperature control branches K1 to K4 are measured by means of temperature sensors 6, and in the embodiment example presented here also with the temperature probes 11 arranged in the molding tool 2. Analogously, temperature profiles H8x and H9x are measured with the temperature probes 11. These are represented in FIG. 3.

[0150] The individual curves in FIG. 3 are plotted along the time axis. In the present embodiment example, the branch temperature profiles RLT01 to RLT04 are the direct measured values from temperature sensors 6, which have been measured in each case in the outlet of the temperature control branches K1 to K4, because the temperature control branches K1 to K4 are fed from the same central inlet, with the result that it can be assumed that the inlet temperatures for the temperature control branches K1 to K4 are in each case identical. For the test, the volume flows of the temperature control branches K1 to K4 have been adjusted by closed-loop control to the same value. The outlet temperature in the respective circuit thus remains as the only factor that is more alterable over time.

[0151] Of course, a preprocessing of the measured signals is possible, for example by filtering.

[0152] Here, the following obvious assignment applies: branch temperature profile RLT01 to temperature control branch K1, branch temperature profile RLT02 to temperature control branch K2, branch temperature profile RLT03 to temperature control branch K3, and branch temperature profile RLT04 to temperature control branch K4.

[0153] The vertical dashed lines in the individual diagrams from FIG. 3 show movements of the plasticizing screw (screw position) of the injection molding machine used, i.e. an injection operation. In each case a pair of vertical lines therefore indicates approximately a new forming cycle, and the duration between adjacent pairs corresponds approximately to the cycle time.

[0154] It can be seen that the measured values react to the heat introduced into the molding tool 2 as a result of the start of production at different rates and to different degrees.

[0155] Analysis of the increase behavior: in detail, it can be seen that the branch temperature profile RLT01 reacts most quickly to the introduction of heat, the branch temperature profile RLT03 reacts next, and the branch temperature profiles RLT02 and RLT04 react the slowest (and on the whole relatively weakly).

[0156] The time of the first increase (here the second cycle in the case of RLT01 and third cycle in the case of RLT03) in the form of a time interval since the start of production (injection operations) can be determined automatically using data evaluation methods known per se.

[0157] The greatest change in the branch temperature in terms of magnitude occurs in the case of temperature control branch K1, followed by K3. Smaller increases occur in the temperature control branches K2 and K4 (the branch temperature profiles RLT01 to RLT04 from FIG. 3 are scaled equally).

[0158] Furthermore it can be seen that branch temperature profile RLT01 and, to a somewhat lesser degree, branch temperature profile RLT03 correlate with the oscillations which occur in the measured values H8x and H9x from the temperature probes 11 arranged in the molding tool 2. This shows that the influence that an individual temperature control branch K1 to K4 has on the heat budget of the molding tool 2 is clearly reflected in these measured values, which is not necessarily to be expected owing to the complex heat situation in the molding tool 2.

[0159] Analysis of the oscillation behavior: this correlation of the oscillations in the branch temperature profiles RLT01 to RLT04 can be analyzed relatively easily with the aid of a Fourier transformation.

[0160] The Fourier transformations of the measurement profiles from FIG. 3 are represented in FIG. 4. Here, the X axis has been scaled in units of multiples of the cycle frequency (thus the reciprocal values of the multiples of the cycle times).

[0161] It can be clearly seen that, in FIG. 4, in the case of the Fourier transforms of the branch temperature profiles RLT01 and RLT03, maxima result at one times the cycle frequency, which are furthermore a good match with the corresponding maxima in the case of the measured values H8x and H9x from the temperature probes 11 in the tool.

[0162] Amplitudes of the oscillations in the branch temperature profiles RLT01 to RLT04 can also be ascertained with reference to the measured values from FIG. 3 and compared with one another. Again, it emerges that the amplitudes in the region of one times the cycle frequency prove to be most pronounced in the case of the branch temperature profile RLT01, second most pronounced in the case of the branch temperature profile RLT03, and weakest in the case of the branch temperature profiles RLT02 and RLT04.

[0163] The maxima of the branch temperature profiles RLT01 to RLT04 and the maxima of the Fourier transforms of the branch temperature profiles RLT01 to RLT04 can also be determined automatically using data evaluation methods known per se.

[0164] It is to be noted that the branch temperature profiles RLT01 to RLT04 each have maxima of different magnitudes at slightly over one half of the cycle time. These can be fluctuations which are present in the temperature of the supplied temperature control medium. In principle, these could be eliminated through measurement of the inflow temperature and subtraction of the branch temperature profiles RLT01 to RLT04.

[0165] FIG. 5 illustrates an embodiment example of the logic in the sorting of the temperature control branches K1 to K4 into categories (which have been numbered consecutively 1, 2 and 3) with regard to the influence on the molded part (the quality of the molded part).

[0166] Following the above-described analysis of the increase behavior (time offset, increase, heat flow), the amplitude of the oscillation behavior and the frequency of the oscillation behavior, the temperature control circuits K1 to K4 can be sorted into the three categories (evaluation of the position of the temperature control runner relative to the cavity/influence on the molded part).

[0167] For example, in the present embodiment example, the temperature control branch K1 associated with the branch temperature profile RLT01 would, according to all three criteria (increase behavior, amplitude, frequency), be to be sorted in each case into category 1 (fastest increase, highest amplitude, highest maximum of the Fourier transformation at one times the cycle time).

[0168] This is followed by the temperature control branch K3 associated with the branch temperature profile RLT03, in category 2, and the temperature control branches K2 and K4 respectively associated with the branch temperature profiles RLT02 and RLT04, in category 3.

[0169] Accordingly, the temperature control branches K1 to K4 are divided into the three categories:

Category 1: temperature control branch K1
Category 2: temperature control branch K3
Category 3: temperature control branches K2 and K4

[0170] Instead of a relative categorization (greatest influence: category 1, smallest influence: category 3) of the temperature control branches K1 to K4, absolute criteria could also be used for the sorting of the temperature control branches K1 to K4 into the categories.

[0171] One example would be [0172] to sort those temperature control branches K1 to K4 of which the times of the first increase lie fewer than X1 cycles after the start of production into category 1, [0173] to sort those temperature control branches K1 to K4 of which the times of the first increase lie more than X1 but fewer than X2 cycles after the start of production into category 2, and [0174] to sort those temperature control branches K1 to K4 of which the times of the first increase lie more than X2 cycles after the start of production into category 3,
wherein X1<X2<X3. This could also be effected analogously for the amplitude or the correlation with the cycle frequency.

[0175] Examples of the limit values would be X1=3 and X2=6.

[0176] In summary, temperature control branches K1 to K4 that are critical (thus important for the quality of the molded part to be produced) are those which have to dissipate large heat flows and/or which are situated close to the cavity surface. The evaluation is effected with regard to [0177] the size of the heat flows and/or through the amplitude of the heat flow in the temperature control branch K1 to K4 and/or the size of the change in the amplitude due to the start/end of molded part production/hot runner circuit, [0178] the proximity to the cavity surface, for example through the rate of change of the heat flow in a temperature control branch K1 to K4 (how quickly does the heat flow increase in which branch?) and the time offset relative to the first injection (the shorter the time, the closer), and [0179] the proximity to the cavity surface, for example through identification of one times the cycle frequency (the closer to the mold cavity 13 a temperature control branch K1 to K4 is situated, the earlier the cycle frequency is identifiable in the temperature control branch K1 to K4; the closer to the mold cavity 13 a temperature control branch K1 to K4 is situated, the more easily identifiable the cycle frequency is; in the latter case: fewer interference effects, reflections, . . . )

[0180] As mentioned, the categories can be defined on the one hand on the basis of predefined limit values for the differing variables discussed, whereby the invention can also be used with a single temperature control branch.

[0181] Embodiments wherein a “most critical” temperature control branch is used as reference for category 1 and the other temperature control branches are defined using relative bounds (for example in the form of percentage values) can be particularly preferred.

[0182] The setpoint values, in this embodiment example setpoint temperature differences, can also be specified corresponding to the categorization according to the invention of the temperature control branches K1 to K4, namely a small setpoint temperature difference for temperature control branch K1, a medium setpoint temperature difference for temperature control branch K3, and a larger setpoint temperature difference for the temperature control branches K2 and K4.

[0183] As desired, this will lead to a greater volume flow through the temperature control branch K1, a medium volume flow through temperature control branch K3 and a smaller volume flow through the temperature control branches K2 and K4 (relative to a maximum possible volume flow through the respective temperature control branch). The volume flow resulting in the case of a closed-loop-controlled temperature difference is also dependent on the heat flow introduced in the respective temperature control branch.

[0184] For example, the following setpoint temperature differences could be specified for the categories:

TABLE-US-00001 Category 1 1° C. or 1° C. Category 2 2° C. 3° C. Category 3 3° C. 5° C.

[0185] Of course, it would also be conceivable that operators specify the setpoint values on the basis of the sorting of the temperature control branches K1 to K4 into the categories.

[0186] Alternatively, setpoint volume flows for the individual temperature control branches K1 to K4 could also be determined directly.

[0187] Even if setpoint values for the open-loop or closed-loop control of the temperature control media flows through the temperature control branches K1 to K4 are not specified directly, important information for operators results from the method according to the invention simply because the temperature control branches K1 to K4 that are critical for the quality of the molded parts to be produced are thereby known, which is illustrated in the photograph from FIG. 6 (the identification of temperature control branches K1 to K4 with greater influence on a portion 3 of the molding tool 2 with a hot runner system 14 is described in conjunction with FIG. 9). FIG. 6 could thus be regarded as a simple representation of the result of the invention.

[0188] If a fault occurs in a circuit that is critical or close to the cavity (category 1), it is clear to the operator, through the knowledge from applying the invention, that this fault can have a direct influence on the quality of their molded part. Possible actions can be fault messages triggered by the control unit, or a production stoppage of the machine.

[0189] A non-critical circuit (category 3) can be dealt with differently in the event of a fault. For example, the control unit can only trigger a notification message but not perform an immediate stoppage of production.

[0190] If, for example, only manual valves are present for the adjustment of throttles for the individual temperature control branches K1 to K4, operators can meaningfully adjust these manual valves on the basis of the categorization mentioned (for example fully opened for temperature control branch K1, medium degree of opening for temperature control branch K3, and small degree of opening for the temperature control branches K2 and K4).

[0191] In any case, a better temperature control of the molding tool 2 with regard to the quality of the molded parts and an intelligent distribution of the temperature control medium, which is present to a limited extent, can be achieved.

[0192] FIG. 7 illustrates the basic physical relationship by means of which, according to the invention, the influence of the temperature control branches K1 to K4 on the heat budget of the molding tool 2 and thus on the quality of the molded parts to be produced can be determined.

[0193] If temperature probes 11 in a molding tool 2 are arranged with certain spacings (see positions P1 to P3 in FIG. 8) relative to a mold cavity or a molding cavity 13, the temperature profiles T1 to T3 represented on the right in the diagram of FIG. 8 result.

[0194] Here, the position P3 is at the cavity wall, position P2 is situated in the molding tool 2 with a certain spacing relative thereto, and position P1 is situated with a somewhat greater spacing. The molding compound 12 which is introduced into the molding cavity/the mold cavity 13 gives rise, at position P3, to a steep temperature profile T3 with a characteristic shape (periodic oscillation). Comparison with the temperature profiles T2 and T1 shows that the steep and characteristic shape quickly decreases in amplitude, and the characteristic shape changes significantly due to the heat propagation, which is more inert compared with the forming cycle. A central aspect of the invention is the knowledge that, through systematic analysis, it can nevertheless be reproducibly identified which temperature control branches K1 to K4 play what role in the heat budget of the molding tool 2. The closer to the cavity surface a circuit is situated, the more pronounced the characterizing features under consideration are.

[0195] In other words, a temperature control branch with the spacing P1 would already have significantly less influence on the molded part than a temperature control branch with the spacing P2 owing to the greater distance. As a result, the volume flow could be reduced, in particular the temperature difference could be increased, there.

[0196] One advantage of the invention is that no temperature probes need to be installed in the tool in order to identify whether a temperature control branch is positioned close to the cavity, but rather the temperature profile in the temperature control medium can be used for the categorization. Any tools can thus be categorized, irrespective of sensor arrangements installed therein.

[0197] In summary, the following physical effects in particular play a significant role in the heat budget of the molding tool 2: [0198] cyclic oscillation of the heat flow (or of the surface temperature) at the cavity surface due to the forming process (injection molding process) [0199] propagation of the thermal wave in the tool steel [0200] the amplitude of thermal waves increases due to an increase of the introduced heat flow per unit area or reduction of the frequency (both are approximately constant in the case of injection molding, for example) [0201] decaying amplitude of the heat flow with increasing distance, damping by tool steel [0202] resultant great heat flow at temperature control branches K1 to K4 in locations in which a great heat flow is introduced [0203] the heat flow requires time to propagate in the molding tool 2 [0204] the heat flow is therefore measurable earlier on the temperature control branches K1 to K4 that are situated close to the mold cavities 13 [0205] the cycle frequency (or cycle time) is therefore identifiable on the heat flow in the temperature control branch K1 to K4 [0206] furthermore, this frequency or the increase of the heat flow is identifiable earlier if the temperature control branch K1 to K4 is situated close to the mold cavity 13

[0207] In the case of constant volume flow, the temperature difference in the temperature control branch can be used instead of the heat flow. In the case of an additionally constant inflow temperature, the outlet temperature of the temperature control branch can be used.

[0208] The invention can also be used in the case of hot runner systems (see FIG. 9). Hot runner systems generally have a separate closed-loop temperature/power control. The controlled variable is normally the temperature of a hot runner zone. However, the hot runner can be only heated (manipulated variable for heating power). For the closed-loop control and heat dissipation, the cooling by the medium in the adjacent temperature control branches is necessary. Without adequate cooling, the zone can overheat. Since the hot runner system has a separate closed-loop control, a stable temperature takes effect if adequate cooling is present.

[0209] It would be conceivable to use the information regarding a sufficiently present temperature control medium volume flow in the temperature control branches ascertained by the invention as having relevance for the hot runner in order to enable/initiate the activation or lowering/deactivation of the hot runner zone.

[0210] A simple example: if the temperature control branch is relevant for the hot runner zone and too little water is flowing (for example because it has been forgotten to activate the temperature control branch or there is a blockage in the temperature control branch), the activation of the hot runner zone (or of the entire hot runner system) can be prevented, or a deactivation or at least a lowering to a non-critical temperature can be initiated. Of course, this can be effected on the basis of the relationship found between hot runner and temperature control branches.

[0211] If the manipulated variable of the hot runner is at the lower limit and the setpoint temperature still cannot be reached (the hot runner is at risk of overheating), the volume flow in the temperature control branch in question can be increased in order to dissipate a higher heat flow and make the closed-loop control possible. If the manipulated variable of the hot runner is at the upper limit (thus does not reach the desired temperature), the volume flow can be reduced in order that less heat is dissipated and heating is made possible.

[0212] FIG. 8 shows an arrangement according to the invention of a forming machine 10 (here, by way of example, an injection molding machine) with a temperature control device 1 according to the invention.

[0213] The molding tool 2 is clamped in the forming machine 10. Temperature control branches K1 to K4, which in this embodiment example are connected in parallel in terms of flow, lead through the molding tool 2.

[0214] It is to be noted that only those line portions which are present within the molding tool 2, and which thereby actively participate in the heat budget of the molding tool 2, are to be understood as temperature control branches K1 to K4 in the true sense (the arrangement of the reference number is for the sake of the clarity of the representation).

[0215] Of course, other hose and line portions (inlet/inflow on the one hand and outlet/return on the other hand) which lead from and to the temperature control device 1 are still present in almost all cases, but in practice do not impair the method according to the invention.

[0216] The temperature control device 1 according to the invention firstly includes a conveying device 7 for generating the volume flow which is conveyed through the temperature control branches K1 to K4.

[0217] After this, in this embodiment example, a temperature sensor 6 is provided for measuring the temperature profile of the supplied medium. Particularly if, as here, the temperature control branches K1 to K4 are fed from a common inlet and the inlet temperature is fairly constant, however, this temperature sensor 6 need not necessarily be present in the inflow.

[0218] The conveying device 7 can also be situated with a spacing relative to the temperature control device.

[0219] This is followed by actuators 4 (here electrically or electronically actuatable throttles with adjustable degree of throttling) for influencing the volume flows through the individual temperature control branches K1 to K4. These could furthermore also be installed in the temperature control branches K1 to K4 after the molding tool 2 in terms of flow.

[0220] After the temperature control media flows have passed through the molding tool 2, they are returned to the temperature control device 1 again. At this point, volume flow sensors 17 and further temperature sensors 6 are provided individually for the temperature control media flows, by means of which the volume flows through the temperature control branches K1 to K4 and the branch temperature profiles RLT01 to RLT04 can be measured. For the use in the method according to the invention, it can be provided that the measured values recorded by the temperature sensor 6 arranged in the inflow are subtracted from the measured values from the other temperature sensors 6, and the branch temperature profiles RLT01 to RLT04 are used in this form as temperature difference in order to eliminate possible temperature fluctuations in the inflow. As mentioned, this is not necessary in all cases.

[0221] In principle, the measured values from the volume flow sensors 17 can also be taken into consideration in the categorization according to the invention of the temperature control branches K1 to K4.

[0222] The processing unit 5 is connected, for transmission of signals, to the temperature sensors 6 for measuring the branch temperature profiles RLT01 to RLT04, preferably also to the central machine controller 9, for example in order to receive information regarding the cycle time and the start of production and/or of the feed of the molding compound 12 to the at least one portion 3 of the molding tool 2.

[0223] The processing unit 5 is formed to perform the above-described method according to the invention. In particular, in this embodiment example, it is provided that the processing unit 5 automatically specifies setpoint temperature differences individually for the individual temperature control branches K1 to K4 on the basis of the method according to the invention.

[0224] Furthermore, the temperature control device 1 in this embodiment example has an open-loop or closed-loop control unit 8, which is likewise connected, for transmission of signals, to the temperature sensors 6, the volume flow sensors 17 and the actuators 4 in order to perform an open-loop or closed-loop control, known per se, according to the temperature difference of the individual temperature control branches K1 to K4.

[0225] Furthermore, in this embodiment example, it is provided that, on the basis of the closed-loop temperature difference control, the open-loop or closed-loop control unit 8 performs a subordinate open-loop or closed-loop control of the volume flows through the temperature control branches K1 to K4, for which purpose the actuators 4 are actuated correspondingly.

[0226] The open-loop or closed-loop control unit 8 can be connected, for transmission of signals, to the processing unit 5 (and/or to the central machine controller), for example in order to obtain the setpoint values specified according to the invention or to receive a signal that the actuators 4 are made equal, in particular fully opened, for the performance of the method according to the invention, and/or the open-loop or closed-loop control is to be suspended for the duration of the method according to the invention.

[0227] Connections for transmission of signals are not represented in FIG. 8 in order to preserve the clarity of the representation.

[0228] The processing unit 5 can be formed integral with the central machine controller 9 of the forming machine 10 and/or the open-loop or closed-loop control unit 8 of the temperature control device 1.

[0229] FIG. 9 schematically shows the structure of a molding tool 2 (injection molding tool) with a hot runner system 14. During normal operation, a plasticized plastic as molding compound 12 is, during the injection operation, conveyed through the hot runner system, onward through the hot runner nozzles 15, and finally into the mold cavity 13.

[0230] Through the method according to the invention, the temperature control branches K1 to K4 (only one of the temperature control branches is provided with a reference number in FIG. 9) that have a stronger thermal coupling to the hot runner system 14 can be identified.

[0231] For this purpose, some of the hot runner nozzles 15 are closed, and thus only the portion 3 of the molding tool 2 that is situated in the vicinity of the open hot runner nozzles 15 is filled with molding compound 12. Through analysis of the increase behavior of the branch temperature profiles, it will emerge that the temperature control branches K1 to K4 that are situated to the right of the mold cavity 13 in FIG. 10 have a greater influence on the heat budget of the portion 3 (thus of the surroundings of the hot runner system 14) of the molding tool 2 than those which are situated to the left of the mold cavity 13 in FIG. 10. With the invention, it can thus be identified which of the plurality of temperature control branches K1 to K4 are situated close to the hot runner system 14, and which are not.

[0232] This could even be used to identify series and/or parallel connections in hot runner systems 14.

[0233] A stepwise activation of heating zones of the hot runner system 14 can furthermore also make a precise assignment possible in this regard.

[0234] As already mentioned, as a portion 3 of a molding tool 2 with several molding cavities 13, it would also be possible to examine only a single molding cavity 13, or a group of molding cavities 13.

[0235] Similarly, with the method according to the invention, it can be identified which temperature control branches K1 to K4 are arranged in the vicinity of an injection apparatus and/or of an injection nozzle of an injection molding machine.

[0236] Finally, the method according to the invention could also be used in the construction of a virtual thermal tool model by performing analyses of an oscillation behavior and/or of an increase or decrease behavior in simulations. The following objects would then be present as virtual objects: the temperature control device 1 and/or the molding tool 2 and/or the actuators 4 and/or the temperature sensors 6 and/or the conveying device 7 and/or the forming machine 10 and/or the temperature probes 11 and/or the molding compound 12 and/or the mold cavity/the molding cavity 13 and/or the hot runner system 14 and/or the hot runner nozzle 15 and/or the ejector 16 and/or the temperature control branches

[0237] The measured characteristic variables of the temperature control branches of the real tool can also be compared with these calculated characteristic variables of the temperature control branches of a tool model from an injection molding simulation. The characteristic thermal behavior of the individual temperature control branches can be compared with the results of the simulation in order to generate an assignment between the circuits of the temperature control device (real structure on the machine) and the circuits of the simulation model. With reference to this assignment, setpoint values present in the simulation or in a dataset (for example volume flow or temperature difference) can for example be set correctly for the corresponding temperature control branches or the correct hose system of the circuits can be checked.

List of Reference Numbers

[0238] Temperature control device 1
Molding tool 2
At least one portion 3 (of the molding tool)

Actuators 4

[0239] Processing unit 5
Temperature sensors 6
Conveying device 7
Open-loop or closed-loop control unit 8
Central machine controller 9
Forming machine 10
Temperature probe 11 (in the molding tool)
Molding compound 12
Mold cavity/molding cavity 13
Hot runner system 14
Hot runner nozzle 15

Ejector 16

[0240] Volume flow sensors 17

[0241] Temperature control branches K1-K4

Branch temperature profiles RLT01-RLT04

Positions P1-P3

[0242] Temperature profiles T1-T3