Temperature control device for a shaping tool and method of controlling same

Abstract

A method of temperature control of a shaping tool or components of a shaping working machine is performed by a temperature control medium disposed in at least one temperature control branch of a temperature control system. A previously ascertained relationship between geometrical data of the at least one temperature control branch and through-flow amounts of the temperature control medium is provided, and a reference through-flow amount is set by the previously ascertained relationship for the geometrical data of the at least one temperature control branch.

Claims

1. A method of controlling a temperature of a shaping tool or components of a shaping working machine via a temperature control medium flowing through at least one temperature control branch of a temperature control system, said method comprising: providing a previously ascertained relationship between geometrical data of the at least one temperature control branch and through-flow amounts of the temperature control medium; and setting a reference through-flow amount based on the previously ascertained relationship for the geometrical data of the at least one temperature control branch; wherein the previously ascertained relationship is expressed by Reynolds numbers, each of the Reynolds numbers being predetermined, and the reference through-flow amount being determined on the basis of the respective predetermined Reynolds number.

2. The method as set forth in claim 1, wherein the geometrical data include at least a diameter—or in the case of non-circular cross-sections a characteristic dimension equivalent to the diameter—of a passage of the at least one temperature control branch.

3. The method as set forth in claim 1, wherein said setting the reference through-flow amount comprises setting the through-flow amount such that the resulting Reynolds number is greater than or equal to the predetermined Reynolds number.

4. The method as set forth in claim 1, wherein a temperature of the temperature control medium is taken into consideration for expressing the previously ascertained relationship by Reynolds numbers.

5. The method as set forth in claim 1, further comprising measuring a relationship between mean temperature differences in at least one temperature control branch and through-flow amounts of the temperature control medium, and wherein said setting the reference through-flow amount is at least partly based on the measured relationship between mean temperature differences of the at least one temperature branch and the through-flow amounts.

6. The method as set forth in claim 5, wherein said setting the reference through-flow amount comprises: determining a first through-flow amount based only on the previously ascertained relationship between geometrical data and through-flow amounts, determining a second through-flow amount based only on the measured relationship between mean temperature differences and through-flow amounts, and setting the maximum of the first through-flow amount and the second through-flow amount as the reference through-flow amount for the temperature control medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the invention will be described below with reference to the Figures, in which:

(2) FIG. 1 is a diagram of an injection molding machine;

(3) FIG. 2 is a graph showing the mean tool wall temperature and through-flow amount; and

(4) FIG. 3 is a graph showing the through-flow amount and the temperature of the temperature control medium.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 is a diagrammatic view of a shaping working machine in the form of an injection molding machine, in the region of a shaping or mold tool 3 having an electronic open or closed loop control device 1 according to the invention. The above-described method can be in the form of a setting assistant in the open or closed loop control device 1. It has an input device 8, a computing unit 9, a memory unit 10, and an output device 11.

(6) It is possible to see parallel temperature control branches 2 through which a temperature control medium (here: water) flows through the shaping tool 3. The temperature of the temperature control medium in the feed 5 to the shaping tool 3 can be ascertained by a temperature sensor 4 which is in signal-transmitting connection with the open or closed loop control device 1. A respective further temperature sensor is arranged in the return from the respective temperature control branch. It is also possible to see a respective through-flow amount sensor 7 for each temperature control branch, and these sensors are also arranged in the returns from the latter. Preferably, a temperature control medium distributor in accordance with AT 12 213 U1 is used. The sensors 4, 4′, 7 are already integrated therein.

(7) Illustrated by way of example for each temperature control branch 2 is an actuator 12 which sets the through-flow amounts.

(8) In regard to FIGS. 2 and 3, it is assumed that the numerical values specified therein were calculated for a temperature control medium in the form of water, FIG. 3 being based on a predetermined Reynolds number Re of 20,000.

(9) FIG. 2 shows along the ordinate the mean tool wall temperature in degrees Celsius, and along the abscissa the through-flow amount in liters per minute of the temperature control medium in a temperature control branch 2. In the region of the origin, it is possible to see a very severe change in the mean tool wall temperature upon a variation in the through-flow amount. In contrast, remote from the origin, scarcely any change in the mean tool wall temperature is to be noted upon a variation in the through-flow amount. Here robust operation of the temperature control device is therefore possible. If there is a wish to operate in the robust region economically in the sense of energy consumption of the temperature control device, then in the graph in FIG. 2 operation will be established as far to the left as possible in the robust region. A possible operating point of that nature is illustrated by way of example by a vertical line. That corresponds to a Reynolds number Re of 20,000. Depending on how robustly and/or economically operation is to be implemented, it is possible to select the operating point in FIG. 2 further to the left or further to the right. An operating point placed further to the right requires more energy but has the advantage of a shorter cycle time, while an operating point placed further to the left requires less energy but has the disadvantage of a longer cycle time and a lower level of robustness. The illustrated Reynolds number of 20,000 represents an advantageous compromise in that respect. The configuration of the relationship between mean tool wall temperature and through-flow amount is independent of the tool, plasticised plastic material and so forth.

(10) FIG. 3 shows along the ordinate the through-flow amount of the temperature control medium in a temperature control branch 2 in liters per minute, and along the abscissa the temperature of the temperature control medium, ascertained by the temperature sensor 4, in the feed 5, in degrees Celsius. The minimum required through-flow amount which is required to achieve a predetermined Reynolds number Re can be ascertained by this graph. The illustrated graph applies to a Reynolds number Re of 20,000 and water as the temperature control medium. Families of curves for different bore diameters are shown, for example a minimum through-flow amount of 4.5 liters per minute occurs independently of the shaped part produced, the tool used and so forth with a feed temperature of 60° C. when using water and a bore diameter of 10 mm.

(11) The above-described method of establishing the minimum reference through-flow amount can be carried out for each of the temperature control branches 2.

(12) Preferably, the described method of ascertaining the minimum reference through-flow amounts is carried out in the on-going shaping process.