PLASTICIZING DEVICE FOR A MOLDING MACHINE

Abstract

A plasticizing device includes a plasticizing cylinder and a plasticizing screw arranged in the plasticizing cylinder. The plasticizing screw is rotatable about, and linearly movable along, a longitudinal axis. The plasticizing screw comprises a functioning section. A sensor is arranged in or on the plasticizing cylinder, and a distance to the surface of the functioning section of the plasticizing screw can be measured by the sensor. A detecting device can detect a type of the functioning section and/or an operating state of the functioning section, can detect a distance signal progression by a movement of the functioning section relative to the sensor, can compare the detected distance signal progression with a stored distance signal progression, and can issue a signal representing the type of functioning section and/or the operating state of the functioning section depending on a matching of the detected distance signal progression with a stored distance signal progression.

Claims

1. A plasticizing device for a molding machine, in particular for an injection molding machine or an injection press, comprising: a plasticizing cylinder, a plasticizing screw which is arranged in the plasticizing cylinder, the plasticizing screw being rotatable about a longitudinal axis and being linearly movable along the longitudinal axis, wherein the plasticizing screw comprises at least one functioning section, a sensor which is arranged in or on the plasticizing cylinder, wherein a distance to the surface of the at least one functioning section of the plasticizing screw can be measured by said sensor, and a detecting device for detecting a type of the functioning section and/or an operating state of the functioning section, the detecting device being configured to detect a distance signal progression generated by a movement of the functioning section relative to the sensor, compare the detected distance signal progression with a stored distance signal progression, and issue a signal representing the type of the functioning section and/or the operating state of the functioning section depending on a matching of the detected distance signal progression with a stored distance signal progression.

2. The plasticizing device as set forth in claim 1, wherein the functioning section is a return flow shut-off device, a screw flight zone of the plasticizing screw or a mixing device.

3. The plasticizing device as set forth in claim 1, wherein the distance signal progression represents the surface contour of the functioning section.

4. The plasticizing device as set forth in claim 3, wherein a surface code formed in the functioning section serves as a means of identification for detecting the type of the functioning section.

5. The plasticizing device as set forth in claim 1, wherein the detection of the distance signal progression is carried out when the plasticizing screw is rotated, when the plasticizing screw is linearly moved along the longitudinal axis or when the plasticizing screw is rotated and moved translationally.

6. The plasticizing device as set forth in claim 1, wherein the stored distance signal progression is stored in a data memory of the plasticizing device or is retrievable from a cloud via a data line.

7. The plasticizing device as set forth in claim 1, wherein: when the functioning section is formed as a return flow shut-off device, the type of the functioning section is a ball shut-off device, a wing shut-off device, a guide path shut-off device, a multi-ball shut-off device or a ring return flow shut-off device, when the functioning section is formed as a screw flight zone, the type of the functioning section is a single-channel screw, a barrier screw, a two-channel screw, a metering zone, a compression zone or a feed zone, and when the functioning section is formed as a mixing device, the type of the functioning section is a tooth lock washer mixing device, a faceted mixing device, a shear mixing device, a shear part, a coiled shear part or a Maddock mixing device.

8. The plasticizing device as set forth in claim 1, wherein the sensor is formed as a sound sensor, preferably as an ultrasound sensor, as an electromagnetic sensor or as a capacitive sensor.

9. The plasticizing device as set forth in claim 1, wherein the sensor comprises at least one measuring head, preferably at least two measuring heads which are distanced from each other along the longitudinal axis or along a circumference.

10. The plasticizing device as set forth in claim 9, wherein the sensor comprises an evaluation unit which is connected with the measuring head.

11. The plasticizing device as set forth in claim 9, wherein the at least one measuring head is arranged on the plasticizing cylinder, preferably on the external side of the plasticizing cylinder, particularly preferred in a drilled pocket formed on the external side of the plasticizing cylinder.

12. The plasticizing device as set forth in claim 1, wherein a control or regulating unit for controlling or regulating movements of the plasticizing screw is provided.

13. The plasticizing device as set forth in claim 12, wherein the detecting device is part of the control or regulating unit or is in a signaling connection with the control or regulating unit.

14. A molding machine comprising a plasticizing device as set forth in claim 1.

15. A method for operating a plasticizing device of a molding machine, in particular an injection molding machine or an injection press, wherein the plasticizing device comprises: a plasticizing cylinder, a plasticizing screw which is arranged in the plasticizing cylinder, the plasticizing screw being rotatable about a longitudinal axis and being linearly movable along the longitudinal axis, wherein the plasticizing screw comprises at least one functioning section, and a sensor which is arranged in or on the plasticizing cylinder, wherein a distance to the surface of the at least one functioning section of the plasticizing screw can be measured by said sensor, wherein a detection of a type of the functioning section and/or the operating state of the functioning section is carried out by the steps moving the function section relative to the sensor, detecting a distance signal progression, comparing the detected distance signal progression with a stored distance signal progression and issuing a signal representing the type of the functioning section and/or the operating state of the functioning section depending on a matching of the detected distance signal progression with a stored distance signal progression.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further details and advantages of the present invention are described more fully hereinafter by means of the specific description with reference to the embodiments by way of example illustrated in the drawings, in which:

[0029] FIG. 1 is a schematic side view of a molding machine with a plasticizing device,

[0030] FIG. 2-3 are cross sections through the plasticizing cylinder in different positions of the plasticizing screw along the longitudinal axis,

[0031] FIG. 5+6 are radial cross sections through the plasticizing cylinder with different rotary positions of the plasticizing screw,

[0032] FIG. 7 is a diagram with an exemplary distance signal progression,

[0033] FIG. 8 is a schematic cross section through a plasticizing cylinder and a plasticizing screw,

[0034] FIG. 9 is a diagram with a distance signal progression corresponding to FIG. 8,

[0035] FIG. 10a-10c are different illustrations of a return flow shut-off device in the form of a single-ball shut-off device,

[0036] FIG. 11a-11c are different illustration of a return flow shut-off device in the form of a central ball shut-off device,

[0037] FIG. 12a+12b are different illustrations of a return flow shut-off device in the form of a multi-wing shut-off device,

[0038] FIG. 13 is a cross section corresponding to the FIGS. 10a to 10c,

[0039] FIG. 14 is a cross section corresponding to the FIG. 11a to 11c,

[0040] FIG. 15 is a cross section corresponding to the FIGS. 12a and 12b,

[0041] FIG. 16a is a front view corresponding to FIG. 10c,

[0042] FIG. 16b is a diagram with a distance signal progression corresponding to FIG. 16a,

[0043] FIG. 17a is a front view corresponding to FIG. 11c,

[0044] FIG. 17b is a diagram with a distance signal progression corresponding to FIG. 17a,

[0045] FIG. 18a is a front view corresponding to FIG. 12c and

[0046] FIG. 18b is a diagram with a distance signal progression corresponding to FIG. 18a.

DETAILED DESCRIPTION OF THE INVENTION

[0047] In FIG. 1, a molding machine 2 is illustrated in a schematic side view. This molding machine 2 comprises a closing unit 11 (illustrated on the left side). This closing unit 11 comprises a movable mold mounting plate 12, a stationary mold mounting plate 13, a mold tool 14 mounted to the mold mounting plates 12 and 13 and a drive device 15 (for example in the form of a toggle lever system) for the movable mold mounting plate 12. At least one cavity K is formed in the closed mold tool 14.

[0048] The molding machine 2 comprises a plasticizing device 1 (illustrated on the right side). This plasticizing device 1 comprises a plasticizing cylinder 3 and a plasticizing screw 4 which is arranged in the plasticizing cylinder 3, the plasticizing screw 4 being rotatable about a longitudinal axis L and being linearly movable along the longitudinal axis L. The plasticizing screw 4 is driven by a—for example electromotive—drive device 16. By means of the feed hopper 18 plastic material, preferably in the form of granules, is filled into the plasticizing cylinder 3 and is melted therein. Melted plastic material is injected into the cavity K in the mold tool 14 by means of the injection channel 19. Then, the injected plastic material is hardening in the cavity K and finally forms at least one molded part (injection-molded part).

[0049] The plasticizing screw 4 comprises at least one functioning section 5. Three exemplary functioning sections 5 are illustrated in FIG. 1—a return flow shut-off device 5a, a mixing device 5b and a screw flight zone 5c. A measuring head 6a of a sensor 6 is associated to each of these functioning sections 5. Each measuring head 6a together with an evaluation unit 6b forms a sensor 6.

[0050] The plasticizing device 2 comprises a detecting device 7 for detecting the type T of the functioning section 5 and/or the operating state B of the functioning section 5. A distance signal progression V is detected by the sensor 6 by moving the functioning section 5 relative to the sensor 6. Specifically, the measuring head 6a of the sensor 6 detects the distance D to the surface of the functioning section 5. During the movement of the plasticizing screw 4 relative to the plasticizing cylinder 3 a new value of the distance D is detected in constant temporal intervals (for example in the range of milliseconds). The entire detected measuring values of the distance D result in a detected distance signal progression V.sub.ist. This detected distance signal progression V.sub.ist is compared with at least one stored (preferably in a memory 8) distance signal progression V.sub.ref. a signal S.sub.T or S.sub.B representing the type T of the functioning section 5 and/or the operating state B of the functioning section 5 is issued (emitted) depending on a matching of the detected distance signal progression V.sub.ist with a stored distance signal progression V.sub.ref.

[0051] The plasticizing device 1 comprises a control or regulating unit 10 (can also be defined as open loop or closed loop control device). The detection device 7 is signally connected with this control or regulating unit 10. Preferably, the signal S.sub.T or S.sub.B representing the type T or the operating State B is transmitted to this control or regulating unit 10. The type T or the operating state B of the checked functioning section 5 detected by the detecting device 7 can be displayed by means of the screen 17. The detected type T or the detected operating state B does not have to be displayed, but rather the corresponding signal can be used or considered when controlling or regulating the movement of the plasticizing screw 4. The operating state B for example can represent two switch positions of the functioning section 5. Specifically, the operating state B can represent the switch position (“closed” or “open”) of the shut-off ring 20 of the return flow shut-off device 5.

[0052] FIG. 2 shows a cross section through the plasticizing cylinder 3 with a plasticizing screw 4. The plasticizing cylinder comprises a flange 21. Drilled pockets 9 are formed on the interior side of the plasticizing cylinder 3. A measuring head 6a of a sensor 6 is arranged in each of these drilled pockets 9. The functioning section 5 is formed as a return flow shut-off device 5a. The return flow shut-off device 5a comprises a shut-off ring 20, the limit stop 22 (in this case in the form of a pressure ring) and several balls 23 (in this case in the form of bearing balls). The plasticizing screw 4 is situated in a forward movement which is indicated by the movement arrow P. Simultaneous, a rotary movement about the rotary axis of the plasticizing screw 3 takes place (see movement arrow R). The distance D at the point in time t.sub.1 is detected by the measuring head 6a.

[0053] In FIG. 3, again, a cross section through the same plasticizing cylinder 3 is illustrated, wherein the plasticizing screw 4 has already moved forward. In this case no second measuring head 6a is illustrated. The distance D to the surface of the functioning section 5 at the point in time t.sub.2 is detected by the measuring head 6a arranged in the plasticizing cylinder 3.

[0054] According to FIG. 4, the distance D to the surface of the functioning section 5 at the point in time t.sub.3 is detected in the same way. In this position according to FIG. 4 the forward movement of the plasticizing screw 4 completed. However, there is still a further rotary movement.

[0055] Correspondingly, FIG. 5 shows a radial cross section through the plasticizing cylinder 3 together with the plasticizing screw 4. The balls 23 of the return flow shut-off device 5a are visible. These balls 23 are arranged around the plasticizing screw 4 in constant distances to each other. The measuring head 6a measures the distance D to the surface (specifically to the locking ball 23) of the functioning section 5 at the point in time t.sub.4.

[0056] According to FIG. 6, the plasticizing screw 4 has been further rotated about the angle W. As a consequence, the distance D between the measuring head 6a and the functioning section 5 has increased. This distance D corresponds to the point in time t.sub.5.

[0057] The recorded distances D at the points in time t.sub.1 to t.sub.5 are combined to a distance signal progression V by the detection device 7. An exemplary distance signal progression V is illustrated in the diagram according to FIG. 7. The distance D detected by the sensor 6 is indicated on the ordinate of this diagram. The time t is indicated on the abscissa of this diagram. As an example the distances D at the different points in time t.sub.1 to t.sub.5 are indicated. This distance signal progression V can correspond to a detected distance signal progression V.sub.ist or to a stored distance signal progression V.sub.ref.

[0058] The FIGS. 2 to 7 can be described in other words as follows: A measuring region of a sensor 6 scans the plasticizing screw 4 during a forward or backward movement of. The sensor 6 can be mounted in the flange 21 or in the plasticizing cylinder 3. The sensor 6 can be formed as an ultrasound sensor. During the axial movement the distances D to the contour of the screw tip and the components connected therewith are measured and recorded. The resulting signal represents to the distance D to a reflection surface or a topography on one or on several components of the plasticizing screw 4 (for example on a return flow shut-off device 5a or on mixing parts). During the movement the distance signal progression V is determined depending on the time t, the position along the longitudinal axis L and the angle W which is scaled with the rate of rotation. Depending on the basic form of the functioning section 5, a characteristic progression occurs which can be distinctly associated to the type T of the functioning section 5. In order to compare the characteristic distance signal progressions V, these progressions are set in relation depending on the position during the temporal progression and the rate of rotation, whereupon the detected graphs are compared by superimposition.

[0059] In FIG. 8, a schematic cross section through a plasticizing cylinder 3 and a plasticizing screw 4 is illustrated. The plasticizing screw 4 comprises a functioning section 5 in the form of a screw flight zone 5c. This screw flight zone 5c comprises one or several screw channels 24 which are helically wound around the plasticizing screw 4.

[0060] When the plasticizing screw 4 according to FIG. 8 is moving in the direction of the movement arrow P and/or when the plasticizing screw 4 is rotating about the longitudinal axis L, the distance signal progression V.sub.ist is detected by the sensor 6. This is illustrated in FIG. 9. The elevations in the distance signal progression V.sub.ist correspond to the groove-shaped screw channels 24 because here the distance D to the sensor 6 is larger than in the region of the screw flights 25. The detected distance signal progression V.sub.ist results in a characteristic signal which is compared with a stored distance signal progression V.sub.ref. Depending on a matching the identified type T of the functioning section 5 is issued. Stored distance signal progressions V.sub.ref can be stored digitally in a sort of a digital library.

[0061] The FIGS. 10a, 10b and 10c show different illustrations of a return flow shut-off device 5a. FIG. 10a shows a lateral view, FIG. 10b shows a cross section and FIG. 10c shows a front view. In this embodiment the return flow shut-off device 5a is formed as a so-called single-ball shut-off device with one single (locking) ball 23 and a shut-off ring 20.

[0062] In contrast, the FIG. 11a (lateral view), 11b (cross section) and 11c (front view) show a return flow shut-off device 5a in the form of a central ball shut-off device. Here, the ball 23 together with the ball seating forms a ball valve. In the region of the screw tip 27 this return flow shut-off device 5a comprises several outflow openings 26 arranged around the longitudinal axis L and in constant distances to each other.

[0063] The FIGS. 12 (cross section) and 12b (front view) show a ring return flow shut-off device 5a in the form of a multi-wing shut-off device. In this embodiment the multi-wing shut-off device comprises three wings 28. These wings 28 are arranged constant distances to each other around the longitudinal axis L.

[0064] FIG. 13 shows a return flow shut-off device 5a according to FIG. 10b which is arranged in a plasticizing cylinder 3.

[0065] FIG. 14 shows a return flow shut-off device 5a according to FIG. 11b which is arranged in a plasticizing cylinder 3 together with a measuring head 6a.

[0066] FIG. 15 shows a return flow shut-off device 5a according to FIG. 12a arranged in a plasticizing cylinder 3.

[0067] FIG. 16a shows the front view according to FIG. 10c and schematically the measuring head 6a. During the rotation of the plasticizing screw 4 the measuring head 6a scans the functioning section 5—in this embodiment the surface of the return flow shut-off device 5a formed as a central ball shut-off device. The characteristic distance signal progression V.sub.ist according to FIG. 16b results from this scanning. The elevations in the distance signal progression V.sub.ist correspond to the lateral flattenings 29 on the return flow shut-off device 5a.

[0068] In contrast, FIG. 17a shows the fron view according to FIG. 11c. The distance signal progression V.sub.ist according to FIG. 17b results from scanning the surface by means of the measuring head 6a (as indicated in FIG. 14). The regularly arranged elevations (see the larger distance D) are easily conceivable. These elevations correspond to the single outflow openings 28 of the screw tip 27.

[0069] FIG. 18a shows the front view according to FIG. 12 of a return flow shut-off device 5a in the form of a multi-wing shut-off device. The elevations in the detected distance signal progression V.sub.ist shown in FIG. 18b correspond to the notches between the wings 28 of the screw tip 27.

LIST OF REFERENCE SIGNS

[0070] 1 plasticizing device [0071] 2 molding machine [0072] 3 plasticizing cylinder [0073] 4 plasticizing screw [0074] 5 functioning section [0075] 5a return flow shut-off device [0076] 5b mixing device [0077] 5c screw flight zone [0078] 6 sensor [0079] 6a measuring head [0080] 6b evaluation unit [0081] 7 detecting device [0082] 8 data memory [0083] 9 drilled pocket [0084] 10 control or regulating unit [0085] 11 closing unit [0086] 12 movable mold mounting plate [0087] 13 stationary mold mounting plate [0088] 14 mold tool [0089] 15 drive device for the movable mold mounting plate [0090] 16 drive device for the plasticizing screw [0091] 17 screen [0092] 18 feed hopper [0093] 19 injection channel [0094] 20 shut-off ring [0095] 21 flange [0096] 22 limit stop [0097] 23 balls (locking ball or bearing ball) [0098] 24 screw channel [0099] 25 screw flights [0100] 26 outflow openings [0101] 27 screw tip [0102] 28 wings [0103] 29 lateral flattenings [0104] L longitudinal axis [0105] D distance [0106] T type of the functioning section [0107] B operating state of the functioning section [0108] V distance signal progression [0109] V.sub.ist detected distance signal progression [0110] V.sub.ref stored distance signal progression [0111] S.sub.T signal representing the type [0112] S.sub.B signal representing the operating state [0113] P movement arrow [0114] R movement arrow [0115] W angle [0116] K cavity [0117] t.sub.1-t.sub.5 points in time [0118] t time