METHOD FOR DETERMINING A PHYSICAL RELATIONSHIP

Abstract

A method of determining a physical relationship between at least one setting parameter of a production cycle of a cyclically operating shaping machine and at least one selected process or quality parameter of the production cycle of the shaping machine, wherein a predetermined variation of a numerical value of the at least one setting parameter is effected in a sequence of production cycles, preferably from one production cycle to another, i and that for each production cycle of the sequence of production cycles the at least one selected process or quality parameter is determined, and that a check is made of the extent to which the at least one selected process or quality parameter has been influenced by the predetermined variation of the numerical value of the at least one setting parameter.

Claims

1. A method of determining a physical relationship between at least one setting parameter of a production cycle of a cyclically operating shaping machine and at least one selected process or quality parameter of the production cycle of the shaping machine, characterized in that a predetermined variation of a numerical value of the at least one setting parameter is effected in a sequence of production cycles, preferably from one production cycle to another, and that for each production cycle of the sequence of production cycles the at least one selected process or quality parameter is determined and that a check is made of the extent to which the at least one selected process or quality parameter has been influenced by the predetermined variation of the numerical value of the at least one setting parameter.

2. The method of claim 1, wherein the extent of the predetermined variation of the numerical value of the at least one setting parameter is effected in dependence on a predetermined tolerance for the shaped parts produced in a production cycle that consequently the production cycles of the sequence of production cycles deliver good parts.

3. The method of claim 1, wherein an adaptation of an amplitude and/or frequency of the predetermined variation of the numerical value of the at least one setting parameter is effected in dependence on the determined at least one process or quality parameter selected.

4. The method of claim 1, wherein the predetermined variation of the numerical value of the at least one setting parameter is effected in accordance with a sine or cosine function.

5. The method of claim 1, wherein the extent to which the at least one selected process or quality parameter has been influenced by the predetermined variation in the numerical value of the at least one setting parameter is checked by means of a Fourier analysis.

6. The method of claim 1, wherein the numerical values of at least two setting parameters are varied simultaneously, wherein the variations of the numerical values of the at least two setting parameters are selected in such way that the effects of the variations on the at least one selected process or quality parameter of the production cycle can be distinguished from each other.

7. The method of claim 1, wherein the numerical value of the at least one setting parameter is kept constant during a production cycle.

8. A method of operating a shaping machine using the results of the method of claim 1, wherein those process or quality parameters which are influenced by a variation of the numerical value of the at least one setting parameter are determined and/or represented or that the at least one setting parameter which influences a process or quality parameter by a variation of its numerical value is determined and/or represented.

9. The method of operating a shaping machine using the results of the method of claim 1, wherein upon entering a desired change of a numerical value of a setting parameter by an operator, a prognosis is made by way of a resulting change of influenced process or quality parameters.

10. The method of operating a shaping machine using the results of the method of claim 1, wherein upon entering a desired change in a process or quality parameter it is specified which setting parameter or setting parameters must be changed to what extent, so that the desired change in the process or quality parameter is set.

11. A method of regulating a shaping machine using the results of the method of claim 1, wherein at least one process or quality parameter selected is automatically regulated by changing at least one setting parameter.

12. A method of monitoring a production cycle of a shaping machine using the results of the method of claim 1, wherein a message for an operator and/or for a control or regulation device of the shaping machine is effected if the extent of the change in the process or quality parameter reaches or exceeds a predetermined threshold value.

13. The method of claim 1, wherein a plastic injection molding machine is used as the shaping machine.

14. The method of claim 13, wherein the at least one setting parameter is selected from the following list: metering volume switching volume switching pressure injection profile holding pressure profile holding pressure time cooling time rotary speed profile dynamic pressure profile cylinder heating tool heating compression relief stroke compression relief speed closing force temperature of a temperature control medium in a flow branch temperature difference between return and flow of a temperature control branch temperature media through-flow in a temperature control branch.

15. A method of claim 1, wherein a process parameter is selected from the following list: injection volume change in viscosity of a plastic melt tool breathing cushion of a plastic melt in a screw antechamber switching pressure injection pressure peak value torque mean value metering drive flow rate of the plastic melt injection work injection time metering time cycle time cooling time temperature difference between return and flow of a temperature control branch temperature control media through-flow in a temperature control branch tool wall temperature internal mold pressure results of a thermography of a component of the plastic injection molding machine, preferably of the tool.

16. -The method of claim 12, wherein a quality parameter is selected from the following list: shaped part mass shaped part dimensions, preferably determined tactilely or optically shrinkage deformation results of an optical testing of the shaped part results of a thermography of the shaped part.

17. A cyclically operating shaping machine comprising: a plurality of actuators which serve to influence a production cycle of the shaping machine in dependence on setting parameters, wherein the shaping machine is provided with a control or regulation device or can be brought into data-transmitting connection with such, characterized in that the control or regulation device is configured in an operating mode which can be triggered automatically or by an operator in order to implement a predetermined variation of a numerical value of at least one setting parameter by means of at least one actuator of the plurality of actuators in a sequence of production cycles, preferably from one production cycle to another, of the shaping machine, and after each production cycle of the sequence of production cycles to determine at least one selected process or quality parameter and to check the extent to which the at least one process or quality parameter selected has been influenced by the predetermined variation of the numerical value of the at least one setting parameter.

Description

[0075] Illustrative embodiments of the invention are discussed by means of the Figures for a sinusoidal variation of the following setting parameters in a plastic injection molding machine:

TABLE-US-00001 Mean Period Setting parameter Abbreviation Unity value Amplitude duration Switching volume C3u cm.sup.3 6.5 0.1 3 Injection speed VS cm.sup.3/s 40 0.8 4 Holding pressure PN bar 400 8 5 level Holding pressure tN sec 10 0.2 7 time Cooling time tK sec 20 0.4 11 Peripheral speed DZ m/s 0.15 0.01 13 Dynamic pressure PS bar 80 1.6 17 Nozzle H2 C. 245 2.45 23 temperature Temperature H3 C. 235 2.35 31 cylinder zone 1 Temperature H4 C. 220 2.2 41 Cylinder zone 2 Temperature H5 C. 205 2.05 97 cylinder zone 3

[0076] FIG. 1 shows a variation in the switching volume in relation to the cycle index:

[0077] mean value 6.50 cm3

[0078] amplitude 0.1 cm3

[0079] period duration 3 cycles

[0080] FIG. 2 shows a variation in the holding pressure level in relation to the cycle index:

[0081] mean value 400 bars

[0082] amplitude 8 bars

[0083] period duration 5 cycles

[0084] FIG. 3 shows a variation in the temperature of a cylinder zone one of a plasticizing cylinder in relation to the cycle index:

[0085] mean value 235 C.

[0086] amplitude 2.35 C.

[0087] period duration 31 cycles

[0088] FIG. 4a shows the effect of the variation of several setting parameters on the process parameter CPx (mass cushion).

[0089] FIG. 4b shows the result of a Fourier analysis with Hanning window. The Fourier analysis shows peaks at the frequencies which correspond to the variations of H3 (cylinder heating zone one), PS (dynamic pressure), tN (holding pressure time), PN (holding pressure level). The process parameter mass cushion can therefore be influenced well by those setting parameters.

[0090] FIG. 5a shows the effect of the variation of several setting parameters on the process parameter APVs (injection pressure peak value).

[0091] FIG. 5b shows the result of a Fourier analysis with Hanning window. The Fourier analysis shows peaks at the frequencies which correspond to the variations of H3 (cylinder heating zone one), VS (injection speed), C3u (switching volume). The process parameter injection pressure peak value can therefore be influenced well by those setting parameters.

[0092] FIG. 6a shows the effect of the variation of several setting parameters on the quality parameter weight (actually shaped part mass).

[0093] FIG. 6b shows a Fourier analysis with Hanning window. The Fourier analysis shows peaks at the frequencies which correspond to the variations of H3 (cylinder heating zone one), PS (dynamic pressure), DZ (rotary speed), tN (holding pressure time) and PN (holding pressure level). The quality parameter weight can therefore be influenced well by those setting parameters.

[0094] FIG. 7 shows an overview about the strength of the relationships between setting parameters (y-axis) and process parameters (x-axis) as a 2D plot by means of a scale from 1 to 9 (1weak relationship, 9strong relationship).