Pressure measuring device for an injection molding machine
A pressure measuring device for an injection molding machine having a plasticizing screw operated by a rotary drive and an injection drive includes a load detector having a deformation zone which forms part of a transmission member of the injection drive and is of reduced cross section, and a sensor. The deformation zone elastically deforms in response to a driving force acting on the transmission member, with the sensor measuring a change in shape of the deformation zone.
1. A pressure measuring device for an injection molding machine having a plasticizing screw operated by a rotary drive and an injection drive, said pressure measuring device comprising a load detector having:
a deformation zone which forms part of a transmission member of the injection drive and has a reduced cross section and which elastically deforms in response to a driving force acting on the transmission member, and
a sensor non-rotatably connected to a non-rotating threaded shaft of the injection drive for measuring a change in shape of the deformation zone.
2. The pressure measuring device of claim 1 , wherein the transmission member is a screw driveshaft provided with a cylindrical shaft portion of reduced diameter to define the deformation zone and is positioned between the plasticizing screw and a bearing for the driveshaft.
3. The pressure measuring device of claim 1 , wherein the transmission member is part of the threaded shaft and has a cylindrical portion of reduced diameter in relation to a diameter of the threaded shaft to define the deformation zone.
4. The pressure measuring device of claim 1 , wherein the sensor is constructed to measure a change in shape of the deformation zone in a contactless manner.
5. The pressure measuring device of claim 1 , wherein the sensor is a laser scanner.
6. The pressure measuring device of claim 1 , wherein the sensor is a laser scanner to detect a change in length and/or thickness of the deformation zone.
7. The pressure measuring device of claim 1 , wherein the sensor is an inductive pickup device.
8. The pressure measuring device of claim 3 , wherein the load detector includes a plunger secured to the cylindrical portion, and a measuring coil secured to the cylindrical portion at a distance to the plunger, said sensor being implemented as an inductive pickup device for measuring a displacement of the plunger in relation to the measuring coil.
9. An injection molding machine, comprising:
a plasticizing screw,
a force transmission member operatively connected to the plasticizing screw;
a rotary drive for rotating the plasticizing screw via the force transmission member;
an injection drive constructed as a spindle drive having a non-rotating threaded shaft acting on the a force transmission member for moving the plasticizing screw in an axial direction, and a threaded nut rotatably mounted onto the threaded shaft; and
a load detector having a deformation zone which forms part of a transmission member of the injection drive and has a reduced cross section and which elastically deforms in response to a driving force acting on the transmission member, and a sensor connected to the threaded shaft for measuring a change in shape of the deformation zone.
10. The injection molding machine of claim 9 , wherein the transmission member is a screw driveshaft provided with a cylindrical shaft portion of reduced diameter to define the deformation zone and is positioned between the plasticizing screw and a bearing for the driveshaft.
11. The injection molding machine of claim 9 , wherein the transmission member is part of the threaded shaft and has a cylindrical portion of reduced diameter in relation to a diameter of the threaded shaft to define the deformation zone.
12. The injection molding machine of claim 9 , wherein the sensor is constructed to measure a change in shape of the deformation zone in a contactless manner.
13. The injection molding machine of claim 9 , wherein the sensor is a laser scanner.
14. The injection molding machine of claim 9 , wherein the sensor is a laser scanner to detect a change in length and/or thickness of the deformation zone.
15. The injection molding machine of claim 9 , wherein the sensor is an inductive pickup device.
16. The injection molding machine of claim 11 , wherein the load detector includes a plunger secured to the cylindrical portion, and a measuring coil secured to the cylindrical portion at a distance to the plunger, said sensor being implemented as an inductive pickup device for measuring a displacement of the plunger in relation to the measuring coil.
17. The pressure measuring device of claim 1 , wherein the load detector has a stationary evaluation circuit operatively connected to the sensor.
18. The injection molding machine of claim 9 , wherein the load detector has a stationary evaluation circuit operatively connected to the sensor.