Apparatus and method for detecting a position of an actuator piston

• US 10,500,775 B2
• Filed: 12/05/2018
• Issued: 12/10/2019
• Est. Priority Date: 08/06/2012
• Status: Active Grant

• Current Assignee: Synventive Molding Solutions Incorporated
• Original Assignee: Synventive Molding Solutions Incorporated
• Inventors: Tan, Zhuang Rui, Yang, Lin
• Primary Examiner(s): Le, Thang X
• Application Number:
  US16/210,055
• Publication Number:
  US 20190105825A1
• Time in Patent Office: 370 Days
• CPC Class Codes: B29C 2045/2865 having position detecting means
• CPC Class Codes: B29C 2945/76083 Position
• CPC Class Codes: B29C 2945/76277 nozzles
• CPC Class Codes: B29C 2945/76381 Injection
• CPC Class Codes: B29C 2945/76488 Magnetic, electro-magnetic
• CPC Class Codes: B29C 2945/76568 Position
• CPC Class Codes: B29C 2945/76755 nozzles
• CPC Class Codes: B29C 2945/76859 Injection
• CPC Class Codes: B29C 45/2806 consisting of needle valve systems B29C45/2896 takes precedence
• CPC Class Codes: B29C 45/281 Drive means therefor
• CPC Class Codes: B29C 45/76 Measuring, controlling or regulating measuring in general G01; controlling or regulating in general G05
• CPC Class Codes: B29C 45/7613 the termination of flow of material into the mould
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 19/402 characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/41107 Coarse by hydraulic cylinder, fine by step motor superposed on piston

Abstract

Apparatus and method for detecting a position of an actuator piston driving a valve pin in an injection molding system. The apparatus includes an actuator housing having a body portion, surrounding an axial bore, of a substantially non-magnetic and/or magnetically permeable material, a piston, movable within the axial bore for driving a valve pin, the piston including a magnetic member generating a magnetic field such that axial movement of the piston in the bore modifies the magnetic field according to the position of the piston relative to a detection position, and a magnetic field detector attached to an exterior surface of the body portion at the detection position for detecting the magnetic field associated with the position of the piston and generating an output signal determined by the piston position.

Claims

1. A control system of an injection molding system for implementing a molding process, comprising:

a control system that controls movement of a valve pin over the course of an injection cycle in accordance with a set of predetermined process parameters, wherein during an injection cycle a nozzle feeds fluid material into a cavity of the mold and the valve pin, driven by an associated actuator, opens and closes a gate into the cavity,

a position sensor associated with the valve pin for monitoring a plurality of actual pin positions with respect to the gate and generating an output signal indicative of the plurality of actual pin positions as the valve pin moves between gate closed and gate open positions,

wherein, during an injection cycle, the fluid material is fed to the nozzle at one or more predetermined times, starting by opening the valve pin at an opening time and allowing the fluid material to flow into the cavity and wherein the fluid material injected from the nozzle forms a molded part in the cavity,

the control system being configured to receive and process the output signal from the associated position sensor to determine, from the plurality of actual pin positions, one or more actual process parameters including an actual pin opening time and actual pin velocities during an injection cycle,

a graphical display receiving and displaying the plurality of actual pin positions and the one or more actual process parameters by which a human operator can track the plurality of actual pin positions and the one or more actual process parameters in real time during the injection cycle.

2. The control system of claim 1, wherein the control system processes the sensor output signal to generate a control signal to control the pin position.

3. The control system of claim 2, wherein the control system includes a user interface for receiving user input for adjusting the control signal to control the pin position.

4. The control system of claim 3, wherein the user interface includes operator commands for one or more modes of operation including self-calibration, continuous monitoring of the actual pin position, and discrete determination of the actual pin position as opened or closed.

5. The control system of claim 1, wherein the graphical display comprises a graph of the actual pin position versus time, based on the sensor output signal, which includes the actual open and closed pin positions and the actual pin positions between the actual open and closed pin positions.

6. The control system of claim 1, wherein the output signal from the position sensor provides continuous monitoring of the actual pin position.

7. The control system of claim 1, wherein the actuator includes a piston for driving the valve pin and the position sensor is a magnetic field detector positioned to detect a magnetic field associated with the actual pin position.

8. The control system of claim 1, wherein the actuator includes a piston that drives the valve pin along a travel path and the position sensor monitors and detects a travel position of the piston as indicative of the actual pin position.

9. The control system of claim 8, wherein the valve pin is driven by the piston along the travel path to the plurality of actual pin positions with respect to the gate between the actual open and closed pin positions.

10. The control system of claim 8, wherein the position sensor is a magnetic field detector positioned to detect a changing magnetic field as the pin moves among the plurality of actual pin positions with respect to the gate between the actual open and closed pin positions.

11. The control system of claim 10, wherein the position sensor comprises a Hall effect sensor.

12. The control system of claim 10, wherein the position sensor comprises a Hall effect circuit including a Hall effect sensor and one or more of a power regulator, signal amplifier, current converter, and signal driver.

13. The control system of claim 8, wherein the control system includes a triggering signal for providing instructions that control a drive mechanism that drives the piston along the travel path, wherein the instructions use the detected travel position of the piston, as the output signal of the position sensor, to instruct the drive mechanism to drive the piston in a predetermined manner during the course of an injection cycle.

14. The system of claim 13, wherein the instructions instruct the drive mechanism to drive the piston along the travel path such that the piston travels continuously upstream from the gate closed position to an intermediate upstream travel position at a first travel velocity and such that the piston travels continuously upstream from the intermediate travel position to a predetermined upstream position at a second travel velocity that is higher than the first travel velocity.

15. The system of claim 8, wherein the position sensor detects the travel position of the piston and the control system is configured to use the detected travel positions of the piston to control movement of the piston along a predetermined path of withdrawal from the gate of the mold cavity at one or more predetermined drive rates or one or more predetermined velocities of withdrawal.

16. A method of monitoring valve pin positioning for implementing a molding process, the method comprising:

controlling, via a control system, a molding process in a common cavity of a mold, to implement a set of predetermined process parameters wherein an actuator drives a valve pin with respect to a gate of the cavity along a travel path including a plurality of actual pin positions between gate open and gate closed positions;

detecting a plurality of actual pin positions of the valve pin, via a position sensor that monitors movement of the valve pin while the valve pin moves along the travel path between the gate closed position and an open position, allowing fluid material to flow through the gate and into the common cavity, and transmitting as a position sensor output to the control system a detected actual movement of the valve pin along the travel path upon opening of the gate indicative of an actual pin opening time and actual pin velocities during an injection cycle;

receiving the sensor output and generating, via the control system, a graphical display indicative of one or more actual process parameters including the actual pin opening time and the actual pin velocities during an injection cycle;

the graphical display generated by the control system enabling a human operator to track the plurality of actual pin positions and the one or more actual process parameters in real time during the injection cycle.

17. The method according to claim 16, wherein the generating step includes generating as the graphical display a graph of continuous actual pin position data versus time.

18. The method according to claim 16, wherein the controlling step includes using the position sensor output as a variable input to control subsequent movement of the valve pin in accordance with the actual process parameters.

19. The method according claim 16, wherein, the valve pin is movable in an associated nozzle, and the controlling step includes controlling the relative velocity at which the fluid material enters into the respective nozzle.

20. The method according to claim 16, wherein during an injection cycle, the fluid material is fed to the nozzle at one or more predetermined times.

21. The method according to claim 16, wherein the graphical display is mounted on an injection machine.

22. The method according to claim 16, wherein the method is adapted for use in calibration of an injection molding system.

23. The method according to claim 16, wherein the method is adapted for use in continuous actual pin position monitoring.

24. The method according to claim 23, wherein the method is adapted for use in actual opened/closed position monitoring of the pin.

25. The method according to claim 16, wherein the sensor comprises a hall effect sensor.

26. The method according to claim 16, wherein the generating step includes generating as the graphical display a graph of the plurality of actual pin positions based on the position sensor output which includes the actual open and actual closed pin positions and positions between the actual open and actual closed pin positions.