Apparatus and method for detecting a position of an actuator piston

• US 9,144,929 B2
• Filed: 08/06/2012
• Issued: 09/29/2015
• 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): Tang, Minh N
• Assistant Examiner(s): LE, THANG XUAN
• Application Number:
  US13/567,609
• Publication Number:
  US 20140035563A1
• Time in Patent Office: 1,149 Days
• Field of Search: 32420711-20726, 324/207.2, 324/207.22, 324/24, 324/26, 324/13, 324/11, 324/262, 417/415, 417/572, 417/417, 417/206, 417/416, 417/469, 417/505, 417/509, 425/145, 425/146, 425/192.R, 425/564, 425/572, 425/568, 425/566
• US Class Current: 1/1
• 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. An apparatus for detecting a position of an actuator piston driving a valve pin in an injection molding system, the apparatus comprising:

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 having a north N pole end and a south S pole end defining a N-S axis and 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;

a hall effect sensor, circuit including one or more hall effect sensors, attached to an exterior surface of the substantially non-magnetic and/or magnetically permeable body portion, wherein the sensor circuit detects the position of the piston relative to the sensor(s) position(s) on the body portion by detecting the magnetic field of the magnetic member as modified by axial movement of the piston in the bore and generates a changing output signal that is unique to each travel position of the piston in the bore based on the detected modified magnetic field; and

wherein each sensor is disposed adjacent either the north N pole end or the south S pole end of the magnetic member, and wherein the magnetic member'"'"'s N-S axis is disposed transverse to the direction of axial movement of the piston in the bore.

2. The apparatus of claim 1, including an electronic controller that processes a value indicative of the output signal to generate a control signal to control the piston position.

3. The apparatus of claim 2, wherein the electronic controller includes a user interface for receiving user input for adjusting the control signal to control the piston position.

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

5. The apparatus of claim 4, wherein in the self calibration mode the piston is actuated by external controls and the electronic controller converts the output signal(s) to position unit(s).

6. The apparatus of claim 2, wherein the electronic controller receives an analog output signal from the hall effect sensor circuit for continuous monitoring of the pin position.

7. The apparatus of claim 2, wherein the electronic controller includes a sampler component for sampling the output signal at a selected sampling rate.

8. The apparatus of claim 1, including an electronic monitor that processes a value indicative of the output signal for monitoring the piston position.

9. The apparatus of claim 1, wherein the valve pin is driven by the piston to multiple positions with respect to a gate.

10. The apparatus of claim 1, wherein the valve pin is positionable between opened and closed positions with respect to a gate.

11. The apparatus of claim 1, wherein the hall effect sensor circuit includes one or more of a power regulator, signal amplifier, current converter, and signal driver.

12. The apparatus of claim 11, wherein the Hall effect sensor circuit generates a voltage output which is proportional to the displacement of the magnetic member relative to the one or more sensors.

13. The apparatus of claim 12, wherein the voltage output is amplified and converted to a current signal by the Hall effect sensor circuit.

14. The apparatus of claim 13, wherein the current signal is transmitted from an output port of the Hall effect sensor circuit to an input port of the electronic controller that generates a control signal based on the current signal to control the axial movement of the piston in the bore.

15. The apparatus of claim 1, further including a display for viewing an indicator of the pin position.

16. The apparatus of claim 15, wherein the display comprises one or more of light(s);

LED(s);

a graph of pin position versus time; and

an indicator of pin opened and pin closed.

17. The apparatus of claim 1, wherein the actuator body portion has a sidewall aligned with the axial bore and each sensor is mounted on the sidewall.

18. The apparatus of claim 1, wherein the axial bore extends between opposing ends of the actuator housing and the hall effect sensor is mounted on one of the opposing ends.

19. The apparatus of claim 1, wherein the magnetic member is located in an aperture in the piston.

20. The apparatus of claim 1, wherein the piston has an enlarged piston head and the magnetic member is located in the piston head.

21. The apparatus of claim 1, wherein the actuator housing is located on a manifold plate.

22. The apparatus of claim 1, wherein the actuator housing is located in the top clamp plate.

23. In an injection molding system, an apparatus for detection of position of a piston disposed within an actuator cylinder, the actuator cylinder comprising a body portion having an interior surface surrounding and defining a bore within which the piston is adapted to move to a plurality of travel positions extending between upstream and downstream positions contained within the bore, the body portion of the actuator cylinder having an exterior surface extending between the interior and exterior surfaces, the apparatus comprising:

a magnetic member having a north N pole end and a south S pole end defining a N-S axis and generating a magnetic field, the magnetic member being mounted to the piston for movement together with the piston between the upstream and downstream positions,

wherein movement of the piston modifies the magnetic field to a modified degree or quality that is dependent on the travel position of the piston relative to a detection position;

the body of the cylinder being substantially non-magnetic and/or magnetically permeable;

a hall effect sensor circuit, including one or more hall effect sensors, attached to the exterior surface of the substantially non-magnetic and/or magnetic magnetically permeable body portion of the cylinder, wherein the body portion of the cylinder is disposed between each sensor and the magnetic member,

each sensor being disposed at a position where the magnetic field of the magnetic member is detectable by the one or more hall effect sensors at all travel positions of the piston between the upstream and downstream positions,

the hall effect sensor circuit detects the modified degree or quality of the magnetic field and generates a changing output signal unique to each travel position of the piston based on the detected modified magnetic field,

a processor receiving the changing output signal generated by the hall effect sensor circuit, the processor using the received signal to determine the travel position of the piston;

wherein each sensor is disposed adjacent either the north N pole end or the south S pole end of the magnetic member, and wherein the magnetic member'"'"'s N-S axis is disposed transverse to the direction of travel of the piston in the bore.

24. The apparatus of claim 23 wherein the processor includes a triggering signal that can be used in providing instructions that control a drive mechanism that drives the piston, the instructions comprising an algorithm that use the determined travel position of the piston to instruct the drive mechanism to drive the piston in a predetermined manner during the course of an injection cycle.

25. In an injection molding system, an apparatus for detection of position of a piston disposed within an actuator cylinder, the actuator cylinder comprising a body portion having an interior surface surrounding and defining a bore within which the piston is adapted to move to a plurality of travel positions extending between upstream and downstream positions contained within the bore, the body portion of the actuator cylinder having an exterior surface extending between the interior and exterior surfaces, the apparatus comprising:

a magnetic member having a magnetic field, the magnetic member being mounted to the piston for movement together with the piston between the upstream and downstream positions,

wherein movement of the piston modifies the magnetic field to a modified degree or quality that is dependent on the travel position of the piston relative to a detection position;

the body portion of the cylinder being substantially non-magnetic and/or magnetically permeable;

a hall effect sensor attached to the exterior surface of the substantially non-magnetic and/or magnetically permeable body portion of the cylinder at the detection position wherein the body portion of the cylinder is disposed between the detection position and the magnetic member,

the detection position being disposed at a position where the magnetic field of the magnetic member is detectable by the hall effect sensor at all travel positions of the piston between the upstream and downstream positions,

the hall effect sensor detects the modified degree or quality of the magnetic field and generates a changing output signal unique to each travel position of the piston based on the detected modified magnetic field,

a processor receiving the changing output signal generated by the hall effect sensor, the processor using the received signal to determine the travel position of the piston;

wherein the processor includes a triggering signal that can be used in providing instructions that control a drive mechanism that drives the piston, the instructions comprising an algorithm that use the determined travel position of the piston to instruct the drive mechanism to drive the piston in a predetermined manner during the course of an injection cycle, and wherein the processor includes a triggering signal that can be used in providing instructions that instruct the drive mechanism to drive the piston such that the piston travels continuously upstream from a gate closed position an intermediate upstream travel position at 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.

26. A method of determining the position of a piston of an actuator piston driving a valve pin in an injection molding apparatus, wherein the actuator comprises:

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 the vale pin, the piston including a magnetic member having a north N pole end and a south S pole end defining a N-S axis and 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,

a hall effect sensor circuit, including one or more hall effect sensors, attached to an exterior surface of the substantially non-magnetic and/or magnetically permeable body portion, wherein the sensor circuit detects the position of the piston relative to the sensor(s) position(s) on the body portion by detecting the magnetic field of the magnetic member as modified by axial movement of the piston and generates a changing output signal that is unique to each travel position of the piston in the bore based on the detected modified magnetic field,

wherein each sensor is disposed adjacent either the north N pole end or the south S pole end of the magnetic member, and wherein the magnetic member'"'"'s N-S axis is disposed transverse to the direction of axial movement of the piston in the bore

the method comprising;

detecting the magnetic field of the magnet member with the hall effect sensor circuit upon axial movement of the piston in the bore,

determining the position of the piston according to the detected magnetic field of the magnet member as modified upon axial movement.