METHOD FOR THE ONLINE SENSING OF THE RHEOLOGY OF THERMOPLASTIC AND/OR ELASTOMER MATERIAL FOR THE PRODUCTION OF INJECTION-MOULDED PARTS

Abstract

The invention relates to a method for the online sensing of the rheology of thermoplastic and/or elastomer material for the production of injection-molded parts, wherein a measuring tool (6) is arranged in an injection-molding machine (1) between the stationary clamping plate (2) and the movable clamping plate (3) thereof instead of a mold die, wherein the measuring tool (6) comprises a measuring channel (13), in the course of which at least two pressure sensors (16) and at least two temperature sensors (17) are arranged, which transfer corresponding measured values of the material injected by means of an injection assembly (5) into the measuring channel (13) to a programmable logic controller (PLC) belonging to the injection-molding machine (1), with these measured values being processed by means of an algorithm in the PLC, evaluated and made available for the actual injection process.

Claims

1. A method for the online sensing of the rheology of thermoplastic and/or elastomer material for the production of injection-molded parts, wherein a measuring tool is arranged in an injection-molding machine between the stationary clamping plate and the movable clamping plate thereof instead of a mold die, wherein the measuring tool comprises a measuring channel, in the course of which at least two pressure sensors and at least two temperature sensors are arranged, which transfer corresponding measured values of the material injected by means of an injection assembly into the measuring channel to a programmable logic controller (PLC) belonging to the injection-molding machine, wherein these measured values are processed by means of an algorithm in the PLC, evaluated and made available for the actual injection process.

2. The method according to claim 1, wherein a slit capillary with a rectangular cross-section is provided as the measuring channel in the measuring tool.

3. The method according to claim 1, wherein in addition to the measurement of temperature and pressure, the mixing state and the wall slip behavior of the injected material are also determined.

4. An injection-molding machine for carrying out the method according to claim 1, having an injection assembly, a stationary clamping plate, a movable clamping plate and a mold clamping device, wherein a measuring tool is arranged between the stationary clamping plate and the movable clamping plate, said measuring tool having a measuring channel that can be supplied with thermoplastic and/or elastomer material by the injection assembly via a runner in the stationary clamping plate, wherein the measuring channel is configured such that it is open at its end opposite the injection assembly, wherein the measuring channel is surrounded by a housing, which is arranged between two mounting plates and comprises a first two-part conically tapering inner part forming the measuring channel and an outer part that is complementary to the inner part and encloses the inner part, wherein at least two pressure sensors and at least two temperature sensors are arranged in the inner part in such a way that at least the measuring diaphragms of the pressure sensors are flush with the inner wall of the measuring channel.

5. The injection-molding machine according to claim 4, wherein the measuring channel is formed as a slit capillary with a rectangular cross-section.

6. The injection-molding machine according to claim 4, wherein the dividing line between the two parts of the first conically tapering inner part of the housing runs along the measuring channel.

7. The injection-molding machine according to claim 4, wherein the transition from the runner into the measuring channel is formed in the corresponding mounting plate in a flow-optimized manner.

8. The injection-molding machine according to claim 4, wherein the pressure sensors are arranged opposite the temperature sensors.

9. The injection-molding machine according to claim 4, wherein the inner part of the housing is mounted on the mounting plate that is fastened on the movable clamping plate, and the outer housing part is mounted on the mounting plate that is connected to the stationary clamping plate.

Description

[0048] The invention will be explained and illustrated below with the aid of drawings.

[0049] The figures show the following:

[0050] FIG. 1: schematic diagram of an injection-molding machine,

[0051] FIG. 2: measuring tool in section,

[0052] FIG. 3: perspective view of a cut-out of the measuring tool

[0053] FIG. 1 illustrates, in highly schematic form, the basic construction of a horizontally operating injection-molding machine, which is provided with the general reference numeral 1. The stationary clamping plate 2 is shown together with the movable clamping plate 3, which moves relative to this clamping plate 2. In the stationary clamping plate 2 a runner 4 is provided, in which the likewise schematically illustrated injection unit 5 fits. The clamping unit, which is responsible for the travelling movement of the movable clamping plate 3 and the build-up of clamping pressure, is not illustrated for reasons of clarity. Between the stationary clamping plate 2 and the movable clamping plate 3 a measuring tool is installed, which is referred to by the reference numeral 6 and is explained in more detail in FIGS. 2 and 3. The measuring tool 6 is arranged between the mounting plates 7 and 8, of which the mounting plate 7 is referred to as an inlet plate and the mounting plate 8 as a support plate.

[0054] In FIGS. 2 and 3, the measuring tool 6 is illustrated in more detail. The measuring tool 6 consists of two housing parts 9 and 10. The outer housing part 9 has an external cylindrical shape, while an opening exists on the inside which tapers conically towards the fixed clamping plate 2. This housing part 9 is mounted on the mounting plate 7. The two-part inner housing part 10, which is fastened on the mounting plate 8 and is configured in principle such that it is complementary to the housing part 9, is introduced into the conical opening of the housing part 9. Thus, the outer housing part 9 serves to center the housing part 10. The two parts of the housing part 10 are configured as truncated cone halves 11 and 12 and in the assembled state they enclose between them a measuring channel 13, which is rectangular in cross-section. The measuring channel 13 is connected via an opening 14 in the mounting plate 7 to the gate 4 in the fixed clamping plate 2. The measuring channel 13 leads into free space at its opposite end at 15.

[0055] In the truncated cone half 12, three pressure sensors 16 are installed one behind the other, their pressure measurement diaphragms being front flush with the measuring channel wall. In the truncated cone half 11, opposite the pressure sensors 16, temperature sensors 17 are installed which are also front flush with the measuring channel wall. On the outer circumference of each half truncated cone, some material has been removed above the holes accommodating the sensors in order to be able to feed the measurement cables of the sensors to the outside. These regions are provided with the reference numeral 18.

[0056] The opening 14 provided in the inlet plate 7 is configured such that it transitions from the round cross-section of the runner 4 to the rectangular cross-section of the measuring channel. The half truncated cone 12 accommodating the pressure sensors 16 is sunk into an indentation in the support plate 8 for centering purposes and is screwed to the support plate from the rear (not illustrated). The truncated cone half 11 is not fastened to the support plate 8 but is screwed to the truncated cone half 12, this being for reasons of stability and so that it can be removed more easily for cleaning the measuring channel 13.