Drive-synchronized metering control and injection molding machine that is operated therewith

A method for drive-synchronized dosing control of an injection molding unit of a machine for processing plastics and other plasticizable materials, comprising a temperature-controllable plasticizing cylinder which has an axial axis and which has a material intake and, in a region at a spacing therefrom, a material discharge nozzle, and arranged in which is a conveying screw that is movable along and rotatable about the axial axis and comprises a backflow blocking device,

• wherein the method comprises the following steps:
• supplying plasticizable material to the material intake of the plasticizing cylinder,
• plasticizing the material to a plasticized material as a result of rotating the conveying screw and at least one of a resulting frictional heat or a temperature control of the plasticizing cylinder,
• conveying the plasticized material into a dosing chamber of the plasticizing cylinder in front of a free end of the conveying screw by rotating the conveying screw in a first direction, wherein a dynamic pressure is formed in the dosing chamber, as a result of which the conveying screw is moved axially away from the material discharge nozzle and a dosing procedure is initiated,
• detecting and storing, in a control unit of the injection molding unit, first process parameters of the injection molding unit,
• at least one of detecting and storing or providing in the control unit further process parameters, which are dependent on the material to be plasticized,
• single or multiple pressure relief of a predetermined dosed quantity in the dosing chamber as a result of at least one of an axial movement of the conveying screw or a rotation of the conveying screw at a first setpoint speed of rotation in a second direction, opposed to the first direction, until at least one of a target angle of rotation of the conveying screw or a target dynamic pressure in the dosing chamber is reached,
• wherein the method comprises:
• evaluating the first process parameters and the further process parameters for determining whether the predetermined dosed quantity has been reached in the dosing chamber, and as a result stopping the dosing procedure by bringing the rotation of the conveying screw and the axial movement of the conveying screw to an end of the dosing procedure in synchronized manner, and
• single or multiple decompression of the predetermined dosed quantity in the dosing chamber by simultaneous axial movement of the conveying screw and rotation of the conveying screw at a second setpoint speed of rotation in the second direction until at least one of a predetermined or predeterminable position at a target distance of the conveying screw from the material discharge nozzle or at a target distance from a previously detected position of the conveying screw is reached,
• wherein a drive for rotation and a drive for axial movement of the conveying screw are synchronized to one another, taking into account at least one actual value each of the first and the further process parameters, such that a dosing of the predetermined dosed quantity, independent on dynamic superimpositions of the further process parameters, and simultaneous stopping of both drives at the end of the dosing procedure are performed, wherein the stopping of the two drives is initiated depending on the speed of return of the material and is synchronized, either in real time or at the start of the stopping procedure, with setpoint courses of the drives that are determined depending on the actual values, and wherein at least the setpoint curve of one of the two drives is variably adapted.

An injection molding unit of a machine for processing plastics and other plasticizable materials, comprising:

• a temperature-controllable plasticizing cylinder comprising an axial axis and, at one end, a material intake configured for supplying plasticizable material, and at an end opposed thereto a material discharge nozzle,
• arranged in the plasticizing cylinder, a conveying screw that is movable along and rotatable about the axial axis and has a backflow blocking device,
• a drive for rotation of the conveying screw in the plasticizing cylinder configured to plasticize material by rotating the conveying screw and at least one of the resulting frictional heat or by temperature control of the plasticizing cylinder and to convey plasticized material into a dosing chamber of the plasticizing cylinder in front of a free end of the conveying screw by rotating the conveying screw in a first direction, wherein a dynamic pressure is formed in the dosing chamber, by which the conveying screw is moved axially away from the material discharge nozzle and a dosing procedure is initiated,
• a drive for axial movement of the conveying screw,
• a control unit of the injection molding unit, and
• devices for detecting and storing first and further process parameters in the control unit,
• wherein the injection molding unit is configured to perform the method as claimed in claim 1.