DE102012008884B4 - Injection molding machine having a function of preventing pinching of plastic material - Google Patents

Abstract

An injection molding machine comprising a cylinder (20) having a feed opening (26, 28) for an injection molding material, a worm shaft (10) having a helical flight (12) rotatably provided in the cylinder (20) and movable in the axial direction , an axial position detector which detects an axial position of the worm shaft (10) in the axial direction and a rotational position detector which detects a rotational angular position of the worm shaft (10), the injection molding machine comprising: a position determination device of the worm gear (12) adapted to be detected a positional relationship between the worm gear (12) of the worm shaft (10) and the feed opening (26, 28) of the injection molding cylinder (20) on the basis of the position of the worm shaft (10) measured and stored by the axial position detector in the axial direction in a plurality from times previously anticipated for a current injection cycle predetermined injection molding cycle, and a rotational angle position of the worm shaft (10) measured by the rotational position detector during the current injection molding cycle at the beginning of the injection process; a passing detecting device configured to determine whether or not the worm passage (12) of the worm shaft (10) passes an opening leading edge of the injection opening feed opening (26, 28) upon advancing the worm shaft (10) during a holding pressure step, on the basis of a determination result the worm gear position detecting device (12) obtained before the start of the holding pressure step and after completion of a metering step, and adjusting device configured to perform based on a detection result of the pass detection device, a setting to a position where the flight ( 12) of the worm shaft (10), the opening leading edge of the feed opening (26, 28) for the injection molding of the injection cylinder (20) during advancement of the screw shaft (10) during the Nachdruckhalteschritts does not happen, characterized in that the rotation of the worm shaft (10) during a pre-pressure holding step is effected.

Description

Background of the invention

1. Field of the invention

The present invention relates to an injection molding machine, and more particularly, to an injection molding machine which enables stable control of the post-injection pressure of the plastic.

2. Description of the Related Art

A cross-sectionally square or round tubular portion of a hopper opening is formed in the injection cylinder of an injection molding machine in a direction perpendicular to the inner peripheral surface of the cylinder, and a worm shaft, a worm, with a flight slides under the portion of the hopper opening in the interior of the injection cylinder. Pellet-shaped plastic is inevitably trapped between the worm gear of the screw and the funnel opening portion in advancing the screw during an injection molding step and a holding pressure step. In some cases, it's not just a plastic pellet that gets pinched, but it's several of them.

During the post-holding step, also repressing step or re-pressing, the screw is normally not driven for rotation. Therefore, a force for crushing the clamped plastic pellets is required when plastic pellets have been pinched in a portion of the hopper opening. The screw is advanced in the direction of the central axis, while at the same time maintaining the state in which the screw is not rotated. The said force causes a sliding resistance between the worm and the cylinder.

A back pressure from the back of the screw is controlled to remain the same and act on the molten plastic in front of the face of the screw to keep the plastic pressure constant in the post-pressure hold step after each injection step. However, a sliding resistance occurs due to pinching of plastic pellets in the portion of the funnel opening, and thus the hold acting on the molten resin falls away regardless of how the back pressure acting from the back side of the screw is controlled to be constant.

For example, the six patent documents discussed below disclose methods for suppressing post-pressure drop due to pinching of pellet-shaped plastic between a flight and a portion of the hopper opening.

Japanese Patent Application Laid-Open JP 2000-135 725 A discloses a feature according to which a part at a portion of a hopper opening communicating with a screw opening of a cylinder is shaped not only to be round or rectangular but to have a shape such that a bin forms an angle β is added in the opposite direction to the pitch angle α of the flight to a part of such a round or rectangular shape. The angle of intersection of the screw flight of the screw with the pocket in the hopper opening is thus increased to α + β, the pellet-shaped plastic slides down the flight at the time of a state in which the screw advances during the post-holding step, then the flight will come in a position that cuts the tray, and the pellet-shaped plastic is pinched. As a result, less pinching occurs between the screw and the hopper opening, and as a result, variations in sliding resistance between the screw and the cylinder are reduced.

Japanese Patent Application Laid-Open JP 2000-263 608 A discloses a technology in which, during the post-pressure holding step, the height of a flight located in the immediate vicinity of the opening leading edge of a feed opening of an injection molding of the injection molding material is lower than that of other sections or has formed a cutout therein as a result, the injection molding material which has been pinched during the post-holding step can be released.

Japanese Patent Application Laid-Open JP 2002-103 409 A discloses a method comprising: determining a rotational angular position and a return position of a screw; Determining a positional relationship between a feed opening through which injection mold chips are fed and the crests and valleys of a continuous flight extending in the axial direction is formed with a helical shape on the outer peripheral surface of a thin elongated shaft, on the basis of the measured rotational angular position and the distance of the return movement of the screw; Predicting a pressure fluctuation that will occur in the near future based on the determination result, and changing the rotational speed of the screw so as to suppress the pressure fluctuations predicted for the near future.

The in Japanese published patent application JP 2000-263 608 A The disclosed technology contemplates only one case of advancing the auger, but not the case where the pellet-shaped plastic is trapped between the auger and a portion of the hopper opening as the auger is moved back to adjust the hold pressure. Moreover, if the shape of the screw is changed, the shape of the portion of the hopper opening must also be changed in accordance with the new shape of the screw. This is problematic in terms of poor economy.

The in Japanese published patent application JP 2000-263 608 A The technology disclosed is therefore problematic because small plastic pellets pass through the gaps between the flight and a heating sleeve. This deteriorates the performance in terms of supplying the plastic to a spray port.

In the method disclosed in Japanese Laid-Open Patent Application JP 2002-103 409 A is disclosed, the sole adjustment of the speed of the screw causes sufficient prevention of the pinching of plastic pellets between the flight and the front or rear opening edge of the feed opening of an injection molding of injection molding material during a Nachdruckhalteschritts.

The document DE 10 2011 102 313 A1 describes a controller for an injection molding machine with a plasticization state monitoring means. An injection screw is rotated by a worm rotary servomotor via a gear unit formed with, for example, a pulley or a belt. Further, the injection screw is driven by an injection servo motor via the gear unit, which has a mechanism for converting the rotational movement of a disk, a belt, a ball screw or a nut mechanism into a linear motion, and moves in an axial direction of the injection screw. The position / velocity of the injection screw in the axial direction is detected by detecting the position / velocity of the injection servo motor by means of a position / velocity detector. The rotational position and the rotational speed of the injection screw are detected by detecting the position / velocity of the worm-rotation servo motor by means of a position / velocity detector.

In the document DE 24 20 686 A For example, a method and apparatus for injection molding glass fiber reinforced thermoplastic material is described. Therein, particles of thermoplastic material are introduced into the cylinders surrounding a reciprocating screw, and separately, glass fibers are supplied to the cylinder in a region delimited by the nozzle end and comprising a homogenizing zone of the cylinder, the feeding being effected when the screw of FIG the nozzle is withdrawn. The separate feeding of the glass fibers and the resin granules, the grinding and grinding of the glass fibers in the cylinder is reduced to a minimum.

A method for controlling a screw shaft position in an injection unit for use in an injection molding system is disclosed in the document WO 2011/103676 A1 known. The injection unit comprises a cylinder arrangement which is adapted to receive a worm shaft. During operation, injection molding material is supplied to a melt channel from a discharge hopper through a supply neck. A rotational movement of the worm shaft is provided by a first actuator, for example an electric servomotor, which is connected thereto via a gear. A rotation sensor, such as a rotary encoder, is associated with the first actuator and configured to measure a current angular position of a rotor within the first actuator.

Summary of the invention

It is an object of the present invention to provide an injection molding machine which avoids the occurrence of variations in injection molding quality caused by pinching plastic pellets between a flight, a screw, and a front or rear opening edge of an injection molding material injection port of an injection cylinder Advancing or retracting the screw by controlling the pressure during a post-pressure holding step after the injection step.

The injection molding machine according to the present invention is provided with an injection molding cylinder having an injection molding material feed opening, a helical-flighted worm shaft rotatably provided in the cylinder and movable in the axial direction thereof, an axial position detector which detects the axial position of the An axial direction of the worm shaft and a rotational position detector detecting the rotational angular position of the worm shaft are further provided with a worm gear position determining device for determining a positional relationship between the worm shaft of the worm shaft and the feed opening of the injection molding injection cylinder on the basis of FIG Axial position detector measured and stored position of the worm shaft in the axial direction at a variety of times, previously for a previous injection molding cycle previous injection Be given the casting cycle, and measured by the rotational position detector during the current injection molding cycle angular position of the screw shaft at the beginning of the injection process.

In a first embodiment, the injection molding machine according to the present invention further comprises:
a passing detecting device for determining whether or not the worm gear of the worm shaft passes an opening leading edge (or opening trailing edge) of the injection molding material feed opening (advancing or retreating) of the worm shaft during the holding pressure step, based on the measurement result of the worm gear position measuring device; was obtained before the start of the holding pressure step and after completion of a metering step, and
an adjusting device for performing, on the basis of a detection result of the passage detecting device, a setting to a position where the worm gear of the worm shaft does not open the opening edge (or opening trailing edge) of the injection material injection hole of the injection cylinder when advancing (or retracting) the worm shaft during the holding pressure step happens by causing the rotation of the worm shaft during a working step preceding the post-pressure holding step.

In a second embodiment, the injection molding machine according to the present invention further comprises:
a passing detecting means for determining whether or not the worm gear of the worm shaft passes an opening leading edge of the injection material feed opening during advancing the worm shaft during the holding pressure step, and whether or not the worm shaft of the worm shaft has an opening trailing edge of the injection material feed opening upon retraction of the worm shaft during the holding pressure step, based on the measurement result of the screw thread position measuring device obtained before the start of the holding pressure step and after the completion of the metering step, and
an adjusting device for performing adjustment by setting, before the start of the holding pressure step and after completion of a metering step, a setting value for a position in the direction of rotation of the screw shaft over the entire post-pressure holding step, on the basis of the detection result of the passport detecting device and a rotational angle value of the screw to make adjustment to a position where the worm gear of the worm shaft does not pass an opening edge of the injection material feed port.

In a third embodiment, the injection molding machine according to the present invention further comprises:
a passing detecting device for determining whether or not the worm gear of the worm shaft passes an opening leading edge (or opening trailing edge) of the injection molding material feed opening (advancing or retreating) of the worm shaft during the holding pressure step, on the basis of the result of the determination of the worm gear position determining device which was obtained before the beginning of the holding pressure step and after completion of a metering step, and
a control switching device for switching the advancing (or retreating) of the worm shaft during the post-pressure holding step from a pressure control to a speed control based on the detection result of the passing detecting device.

In the first to third embodiments, the injection molding machine according to the present invention may further include an apparatus for reading out the shape of a flight from a database in which the shape of the flight is contained in the form of equations solely by inputting a number for include the helical shape.

The present invention, constituted by the elements constituting the elements described above, can provide an injection molding machine which makes it possible to avoid occurrence of variations in injection molding quality caused by pinching plastic pellets between a worm shaft of a worm shaft and the front or rear opening edge of a feed opening for injection molding material of the injection molding cylinder when advancing or retracting the worm shaft, by controlling the pressure during a post-pressure holding step after spraying.

Brief description of the drawings

1A and 1B 13 are diagrams for explaining a case of advancing the leading end of the top of a screw flight of a screw during a post-pressure holding step as viewed from the injection material injection port of a cylinder;

2A and 2 B 13 are diagrams for explaining a case of returning the front end of the top of a screw flight of a screw during a post-pressure holding step, as viewed from the injection material injection port of a cylinder;

3 is an illustration for explaining a worm gear of a screw and an opening leading edge of a feed opening for injection molding of a cylinder;

4 Fig. 12 is an illustration for explaining the reproduction in the form of an equation of the location of the front end of the top of a screw flight of a screw and an opening leading edge of a rectangular feed opening for an injection molding material of a cylinder;

5 Fig. 13 is an illustration for explaining a location of the front end of the top of a worm gear of a worm and an opening leading edge of a feed opening for an injection molding material of a cylinder;

In 6 FIG. 14 is a diagram for explaining a front end portion of a screw flight upper portion of a screw in which there is a possibility that plastic is interposed between the front end of the upper side of a screw flight of a screw and an opening leading edge of an injection port of a cylinder Plastic pellets at a position x = x ₄ at which the worm has been advanced furthest during a hold-pressure holding step;

7 15 is a diagram for explaining a projection on a yz plane for which x = b, a predicted value at a position where a dosing step is completed (x = x ₁ ), a range in which there is a possibility that the leading end of the upper side of a screw flight of a screw causes plastic to be pinched between the leading end of the upper side of a flight and an opening leading edge of an injection molding material feed port of a cylinder during advancing of the screw during a post-pressure holding step;

8th 11 is a diagram for explaining a position following the front end of the top of a flight of a worm in an xy plane for which x = b due to advancing the worm during a post-pressure holding step when a range of ρ is a case (1) in which ρ represents a range of a rotational angle phase θ 'of a screw flight of a screw for which there is a possibility of a plastic pellet being pinched between the front end of the top of the screw flight of the screw and the tip leading edge of an injection material feed port;

9A to 9F 15 are diagrams for explaining a location followed by the front end of the top of a flight of a worm in an xy plane for which x = b after advancing the worm during a post-pressure holding step when a range of ρ corresponds to a case (2) ;

10A and 10B Fig.14 is diagrams for explaining a location followed by the front end of the top of a flight of a screw in an xy plane for which x = b after advancing the screw during a post-pressure holding step when a range of ρ corresponds to a case (3) ;

11 Fig. 12 is a diagram for explaining a case where f '(θ ₃ ) projected on a yz plane for which x = b holds corresponds to a condition (1);

12A and 12B Fig. 11 are diagrams for explaining conceivable positions of ρ in the case of a condition (1) and for explaining an example of an avoidance operation;

13 Fig. 12 is a diagram for explaining a case where f '(θ ₄ ') projected on a yz plane for which x = b is a condition (2);

14A and 14B Fig. 11 are diagrams for explaining conceivable positions of ρ in the case of a condition (2) and for explaining an example of an avoidance operation;

15 Fig. 12 is a diagram for explaining a case where f '(θ ₃ ) and f' (θ ₄ ') projected on a yz plane for which x = b is a condition (3);

16A and 16B Fig. 11 are diagrams for explaining conceivable positions of ρ in the case of a condition (3) and for explaining an example of an avoidance operation;

17 Fig. 13 is a diagram for explaining a case where f '(θ ₃ ) and f' (θ ₄ ') projected on a yz plane for which x = b holds correspond to a condition (4);

18A and 18B Fig. 11 are diagrams for explaining conceivable positions of ρ in the case of a condition (4) and for explaining an example of an avoidance operation; 19 Fig. 13 is a diagram for explaining a case where f '(θ ₃ ) and f' (θ ₄ ') projected on a yz plane for which x = b is a condition (5);

20A and 20B Fig. 11 are diagrams for explaining conceivable positions of ρ in the case of a condition (5) and for explaining an example of an avoidance operation;

21 Fig. 12 is a diagram for explaining a case in which f '(θ ₃ ) and f' (θ ₄ ') projected on a yz plane for which x = b is a condition (6);

22A and 22B Fig. 15 are diagrams for explaining conceivable positions of ρ in the case of a condition (6) and for explaining an example of an avoidance operation;

23 Fig. 3 is an illustration for illustrating a worm gear of a worm and an opening trailing edge of an injection material injection port of a cylinder;

24 11 is a diagram for explaining a transmission in the form of an equation of the position of the rear end of a worm gear top of a worm and an opening trailing edge of a rectangular feed opening for injection molding of a cylinder

25 11 is an illustration for explaining a position of a rear end of a screw flight top of a screw, which has an opening trailing edge of an injection mold material feed opening of a cylinder upon returning the screw from a position (x = x ₄ ) of the furthest advance of the screw in a post-pressure holding step to the start position of a metering step (x = x ₀ ) happens;

26 FIG. 14 is an illustration for explaining a portion of the rear end of a worm gear top of a screw in which there is a possibility that plastic is caught between the rear end of the worm gear top and an opening trailing edge of an injection mold material feed opening of a cylinder taking into account the size of the plastic pellet at the start position of a cylinder Dosing step x = x ₀ );

27 is a view showing a projection on a yz plane, = j is valid for the x, a predicted value at an end position (x = x ₁₎ of a metering step, a region in which there is the possibility that the rear end of the worm gear top a worm causes a plastic to be trapped between the rear end of the worm gear top and an opening trailing edge of an injection molding material feed opening of a cylinder upon retraction of the worm during a post-pressure holding step.

28 13 is a diagram for explaining a position followed by the trailing end of a worm gear top of a worm shaft in a yz plane for which x = y during advancement of the worm shaft during a post-pressure holding step when a range of η corresponds to a case (4); by doing η corresponds to a range of a rotational phase λ 'of the worm shaft of the worm shaft, in which there is a possibility that plastic pellets are pinched between the rear end of the worm gear top of the worm shaft and an opening trailing edge of an injection material feed port;

29A to 29F Fig. 12 is diagrams for explaining a position followed by the trailing end of a worm gear top of a worm shaft in a yz plane for which x = j during retraction of the worm shaft in a post-pressure holding step when a range of η corresponds to a case (5).

30A and 30B Fig. 12 is diagrams for explaining a position followed by the trailing end of a worm gear top of a worm shaft in a yz plane for which x = j during retraction of the worm shaft in a post-pressure holding step when a range of η corresponds to a case (5).

31 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') projected on a yz plane where x = j holds corresponds to a condition (4);

32A and 32B Fig. 11 are diagrams for explaining conceivable positions of η in the case of the condition (7) and for explaining an example of an avoidance operation;

33 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') projected on a yz plane where x = j holds corresponds to a condition (8);

34A and 34B are illustrations for explaining conceivable positions of η in the case of the condition (8) and for explaining an example of an avoidance operation;

35 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') and g '(λ ₄ ) projected on a yz plane for which x = j holds correspond to a condition (9);

36A and 36B Fig. 11 are diagrams for explaining conceivable positions of η in the case of the condition (9) and for explaining an example of avoidance operation;

37 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') and g '(λ ₄ ) projected on a yz plane for which x = j is given a condition (10);

38A and 38B are illustrations for explaining conceivable positions of η in the case of the condition (10) and for explaining an example of an avoidance operation;

39 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') and g '(λ ₄ ) projected on a yz plane for which x = j holds, corresponds to a condition (11);

40A and 40B Fig. 11 are diagrams for explaining conceivable positions of η in the case of the condition (11) and for explaining an example of an avoidance operation;

41 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') and g '(λ ₄ ) projected on a yz plane for which x = j holds correspond to a condition (12);

42A and 42B are illustrations for explaining conceivable positions of η in the case of the condition (12) and for explaining an example of an avoidance operation;

43 is an illustration for explaining a worm gear of a screw shaft and an opening leading edge of a circular feed opening for injection molding of an injection cylinder;

44 Fig. 12 is a diagram for explaining reproduction in the form of an equation of the position of the front end of a worm gear top of a worm shaft and an opening leading edge of a circular feed opening for injection molding material of a cylinder;

45 is an illustration for explaining a worm gear of a worm shaft and an opening trailing edge of a circular feed opening for injection molding of a cylinder; and

46 11 is a diagram for explaining a reproduction in the form of an equation of the position of the rear end of a worm gear top of a worm shaft and an opening trailing edge of a circular feed opening for injection molding material of a cylinder.

Description of preferred embodiments

Here, the essence of the present invention will be explained. The injection molding machine according to the present invention can avoid variations in the quality of an injection molded product by controlling the pressure during the holding pressure step resulting from a resistance caused by pinching a plastic pellet between the worm shaft of the worm shaft and the front or rear opening edge of the injection molding material injection opening of the injection molding cylinder may be effected after advancing or retracting the worm shaft, so that this resistance causes a drop in the repressurization during the backward movement of the worm and hinders a reduction of the pressure during the retraction of the worm.

In other words, the present invention prevents plastic pellets from being trapped between the opening leading edge or the trailing edge of the feed opening of the injection molding material and the flight, by controlling the speed without simultaneously controlling the pressure during the holding pressure step or by adjusting or Adjusting the position of the worm by causing the worm to rotate at a time before the post-holding step in the case where it was detected that the worm gear on the worm shaft is at a position in its rotational direction or at a position in the axial direction the worm stands where there is a possibility that the worm gear causes a pellet between the worm gear and the opening leading edge or the opening trailing edge of the feed opening for the injection molding of the injection cylinder ei is clamped, from the time of completion of a dosing step to the Nachdruckhalteschritt and then in the Nachdruckhalteschritt. As a result, variations in the emphasis are removed and the quality of the molded product is improved.

According to the present invention, adjustment is made to a position where the flight does not pass the opening leading edge of the injection molding material injection opening of the injection molding cylinder during the post-pressure holding step by causing the screw to rotate in one phase before the post-holding step as shown in FIG 1 is shown, in a case in which it has been determined that the front end of the worm gear top of the screw is in the direction of rotation of the screw in a position in which there is a possibility that the front end of the worm gear top causes a plastic pellet between the front End of the worm gear top and the opening leading edge of the feed opening for the injection molding material (molding material) of the injection cylinder, is clamped by advancing the screw during the Nachdruckhalteschritts. Alternatively, speed control is performed without pressure control during the pressure hold step. This causes the worm to be rotated by a servomotor for its rotation and moved in the axial direction of the worm by means of a mechanism which converts the rotary motion of a servomotor into a linear motion for advancing and retracting the worm shaft. The position of the screw in the axial direction and the rotational position about the axis are measured by position and speed detectors provided in the servomotors. The injection molding machine having the aforementioned servomotors is controlled by means of a control device. Such a control device is known in the art. The present invention is realized in a control device of the injection molding machine.

1A and 1B FIG. 12 are diagrams for explaining an instance or a case of advancing a leading end. FIG 14f the worm-gear top of a snail 10 during a post-pressure holding step, viewed from a feed opening 26 for an injection molding material of the cylinder 20 out.

In 1A denotes the reference numeral 100 the opening leading edge of a task opening 26 for the injection molding material in the screw cylinder 20 ; the reference number 102 denotes the feed travel (= x ₄ - x ₃ ) between a position x ₃ (x ₃ will be described later) at which the worm shaft 10 or a screw from a speed control to a pressure control, up to a position x ₄ (x ₄ will be explained later) of the furthest advancement or advance of the worm 10 during the post-pressure holding step; the reference number 104 denotes a position where there is a possibility that plastic pellets are set during the pressure-holding step, and the reference numeral 106 is a cross-sectional view of the screw 10 of the 1A along the dashed line AA. 1B put the snail 10 in 1A without changing its position in the direction of the central axis, but rotated by 180 ° about the central axis.

In 1B denotes the reference numeral 108 a location where there is little likelihood of a plastic pellet becoming trapped during the post-pressure holding step, and the reference numeral 110 is a cross-sectional view of the screw 10 of the 1B along the dashed line BB. A comparison between the in 1A position shown 104 and the in 1B position shown 108 illustrates, therefore, that when the phase of the direction of rotation of the screw 10 Also, the size of the location or area at which there is a possibility that plastic pellets between the front end 14f the worm-gear top of the snail 10 and the opening leading edge 100 the task opening 26 for injection molding material of the cylinder 20 due to the advance of the screw 10 is trapped during the post-pressure holding step.

2A and 2 B FIG. 12 are diagrams for explaining an instance of the backward movement of the front end of the worm gear top of the worm. FIG 10 during the holding pressure step, viewed from the feed opening of the cylinder 20 for the injection molding material.

In 2A denotes the reference numeral 120 an opening trailing edge of the feed opening 26 for the injection molding material of the cylinder 20 ; the reference number 122 gives a travel distance (= x ₄ - x ₀ ) from a position (x ₄ will be explained later) of the furthest advancement of the worm 10 during the post-pressure holding step up to a start position x _{0 of} a dosing operation (x ₀ will be described later); the reference number 124 denotes a location where there is a possibility of plastic pellets becoming trapped during the pressure holding step; the reference number 126 is a cross-sectional view of the screw 10 of the 2A along the dashed line AA. Here shows 2 B the snail 10 in 2A without changing its position or position in the center axis direction, but rotated 180 ° around the center of the shaft.

In 2 B denotes the reference numeral 128 a location where there is a possibility of plastic pellets becoming trapped during the post-holding step, and designates the reference numeral 130 a cross-sectional view of the screw 10 of the 2 B along the dashed line BB. Here makes a comparison between the in 2A position shown 124 and the in 2 B position shown 128 clearly that when the phase of the direction of rotation (the angle of rotation) of the screw 10 varies as well the size of the range varies, in which there is the possibility that plastic pellets between a front end 14a the worm-gear top of the snail 10 and the opening trailing edge 120 the task opening 26 for the injection molding material of the cylinder 20 when moving back the snail 10 be trapped during the post-pressure holding step.

1st embodiment

A first embodiment of the present invention will be described below with reference to the accompanying drawings for a case where the feed opening 26 for the injection molding material of the cylinder 20 is rectangular and the snail 10 during the post-pressure holding step.

3 is a representation illustrating a worm gear 12 the snail 10 and the opening leading edge of a rectangular feed opening 26 for the injection molding material of the cylinder 20 , A filler block 24 is on the rear outer surface of the cylinder 20 attached. The rectangular task opening 26 for the injection molding material reaches through the screw cylinder 20 and the filler block 24 and stands with the interior of the cylinder 20 for the snail in connection. The snail 10 with the helix 12 is in the auger bore of the cylinder 20 so provided that they are the worm 20 around the central axis 16 turn and in the direction of the central axis 16 can move (forward and backward direction). An unillustrated hopper for the supply of plastic pellets is above the filling block 24 intended. The reference number 22 denotes a nozzle. Thus, the molten plastic through the nozzle 22 be injected in an injection mold, not shown, or a tool. Determining the position of the screw 20 in the forward and backward direction as well as the determination of the rotation angle or the rotational position of the screw 10 are well-known features in the art of injection molding machines and therefore their explanation is omitted.

In 3 denotes the reference numeral 140 an enlarged partial view to explain the location at which the worm bore of the injection cylinder 20 with the rectangular task opening 26 in the filler block 24 for the injection molding material and in the cylinder 20 is associated with, the reference numeral 142 a representation of the task opening 26 for the injection molding material with a view from above the rectangular task opening 26 for the injection molding material. The reference number 144 in the figure indicates the location where there is a possibility that plastic pellets between the front end 14f the top of the helix 12 the snail 10 and the opening leading edge of the task opening 26 for the injection molding material of the cylinder 20 due to the forward movement of the screw 20 be trapped during the post-pressure holding step. The reference number 146 denotes a diagram for explaining a design of the front end 14f the worm-gear top of the snail 10 , the reference number 147 in the figure, a shape of the opening leading edge of the feed opening for the injection molding of the cylinder 20 and the reference numeral 148 denotes a type of the front end 14f the top of the helix 12 the snail 10 ,

As in 3 shown, the position of the front end 14f the worm gear top of the worm gear 12 the snail 10 at a rotational angle (angular position) and a position in the direction of the forward and backward movement thereof opposite to the opening leading edge of the feed opening 26 for the injection molding material of the cylinder 20 distinguished by rendering in the form of equations of the shape of the flight 12 the snail 10 as well as the shape (rectangular shape) of the opening leading edge of the feed opening 26 for the injection molding material of the cylinder 20 ,

4 Fig. 12 is an illustration for explaining the manner of the location of the front end 14f the top of the helical flight of the snail 10 and the opening leading edge of the rectangular task opening 26 for the injection molding material of the cylinder 20 in the form of equations. Here denotes the front end 14f the top of the flight the edge of the top of the flight 14 on the side of the front end of the snail 10 like this in 3 is shown. The back end 14r the worm gear top denotes the edge of the worm gear top 14 on the side of the base end (rear end) of the worm shaft 10 ,

The xyz coordinates are initially as in 4 shown set. The y axis and the z axis are set in such a way that the central axis 16 the worm shaft 10 lies on the x-axis. Here, R is the distance from the x-axis to the top 14 of the worm gear 12 the worm shaft 10 , The coordinate origin of the xyz coordinates is set in such a way that the starting point of the helix line of the front end 14f the worm-gear top of the snail 10 x = 0, y = R, z = 0 is in the state in which the worm 10 is in a furthest advanced position. For this case, the equation for the helix line of the front end 14f the worm-gear top of the snail 10 in the form of the following equation (1). The rotational phase θ of the screw 10 is set to (0 ≦ θ ≦ 2nπ), where n is a natural number.

The rotational phase θ, the return stroke X from the most advanced position of the worm 10 and a rotation angle c are further added. As stated above, the position of the maximum advancing movement of the worm becomes 10 chosen as the origin, leaving the snail 10 can only be moved back and thus X ≤ 0. The normal direction of rotation of the screw 10 runs clockwise from the side of the spray outlet (the side of the nozzle 22 ) of the cylinder 20 and runs in an opposite direction of rotation in the yz plane, and hence c ≦ 0. Thus, the equation is the helical curve of the front end 14f the helical side of the snail 10 in a retracted position X and at a rotation angle c given by the following equation (2).

The opening leading edge of the task opening 26 for the injection molding material of the cylinder 20 is reproduced in the form of a mathematical equation listed below. The origin is specified to be identical to the original origin O of the xyz coordinates for which the shape or shape of the helical flight 12 the snail 10 is represented in the form of an equation. The opening leading edge of the task opening 26 for the injection molding material lies in a plane which runs parallel to the xy plane at a location offset from the origin O by a distance x = b. The phases of the segments, both ends of the opening leading edge of the task opening 26 for the injection molding material and the x axis (the with the center axis of the injection cylinder and the central axis 16 the snail 10 match) are d and e. Accordingly, the opening leading edge of the feed opening 26 for the injection molding material of the cylinder 20 represented by the following equation (3).

The intersection of the equation (2) and the equation (3) on the x-axis is represented in the form of the equation (4). This intersection corresponds to the position of the front end 14f the worm-gear top of the snail 10 at the opening leading edge of the task opening 26 for the injection molding material of the cylinder 20 ,

Here x _{1 is} the position at which the worm 10 stops the dosage of the molten plastic and stops its rotation. Further, x _{2 is} the position at which the backward movement of the worm 10 is completed from the above position in a depressurization step. Furthermore, x ₃ denotes the position at which subsequently the screw 10 is switched from a speed control to a pressure control in an ejection step, and x _{4 is} the forwardmost position of the worm 10 during the hold pressure step. These positions x ₁ , x ₂ , x ₃ and x _{4 of} the screw 10 can be measured and recorded by known methods. The position x ₁ , x ₂ , x ₃ and x _{4 of} the screw 10 are recorded and averaged for each injection and the mean values of these X ₁ , X ₂ , X ₃ and X ₄ are then used. Instead of the mean values X ₁ , X ₂ , X ₃ and X ₄ , mean values (moving average values) of the position x ₁ , x ₂ , x ₃ and x _{4 of} the worm 10 for n spraying operations (n is a natural number) immediately preceding the current spraying operation. Taking the mean value of the motion as n = 1, then the position x ₁ , x ₂ , x ₃ and x _{4 of} the worm can also 10 are used as an injection molding cycle preceding the current injection molding process by the value of one. For the first spraying operation, which does not have an immediately preceding spraying operation, a predetermined value for the post-rotation position may be given for a complete metering step of the auger 10 As the value X ₁ can be used, a predetermined value for the position of the complete pressure reduction, to which the worm 10 in the depressurization step, when the value X ₂ is used, a predetermined value of the position at which for the screw 10 is switched from a speed control to a pressure control, as the value X ₃ can be used and the origin O of the worm 10 as the value X ₄ are used.

The time at which for the snail 10 is switched from speed control to pressure control in the injection molding step, as well as the time of the furthest forward movement of the screw 10 during the hold pressure step are preset in advance.

The relationships according to the following equation (5) are for the positions x ₁ , x ₂ , x ₃ and x _{4 of} the screw 10 for each injection molding operation and between the values X ₁ , X ₂ , X ₃ and X ₄ obtained by storing and averaging the position x ₁ , x ₂ , x ₃ and x _{4 of} the screw 10 were obtained for each injection. x ₂ ≦ x ₁ ≦ x ₃ ≦ x ₄ ≦ 0, X ₂ ≦ X ₁ ≦ X ₃ ≦ X ₄ ≦ 0 (5)

Further, c ₁ denotes the rotation angle of the worm 10 at position x ₁ , where the worm 10 finished the dosage of the molten plastic and stopped the rotation. Next is a description of a particular method for determining if the leading end 14f the worm-gear top of the snail 10 the opening leading edge of the task opening 26 for the injection molding material of the cylinder 20 happened and plastic pellets due to a forward movement of the screw 10 or not by using X ₁ , X ₂ , X ₃ and X ₄ and c ₁ as well as the above-described equation (1), equation (2), equation (3), equation (4) and equation (5) showing the positional relationship between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 describe.

Usually the auger rotates 10 from the completion of the dosing step until the beginning of the next dosing step. Therefore, the rotation angle c _{1 of} the worm 10 at the end position x ₁ for the dosing step equal to the angle of rotation of the screw 10 at position X ₃ , where the worm 10 from speed control to pressure control, and at position x ₄ where the worm is moved furthest forward during the post-holding step. Note that "at the start of the spattering," referred to in "determining the positional relationship between the screw flight of the screw and the injection material injection hole of the injection cylinder, based on ... a rotational angular position of the screw at the start of injection" is not limited to the point in time at which the injection process begins, but at any time between the end of the dosing step and the beginning of the injection step.

The front end 14f the worm-gear top of the snail 10 happens the opening leading edge of the task opening 26 for injection molding material in the cylinder 20 while the snail 10 from the position x = x ₃ , where the worm 10 from speed control to pressure control, until the position x = x ₄ at which the worm moved furthest forward in the post-pressure holding step is advanced. 5 is a diagram for explaining the passage location of the front end 14f the worm-gear top of the snail 10 ,

As with (a) the 5 shown, θ ₃ denotes the rotational phase of the screw 10 at the intersection between the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 (xy plane, for which x = b holds) and the front end 14f the top of the helical flight of the snail 10 at position x ₃ , at which the snail 10 changed from speed control to pressure control. Here, f (θ ₃ ) from equation (2) at the time point where θ = θ ₃ gives the coordinates of the intersection between the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 (xy plane at the point x = b) and the end face 14f the helical flight top (flight top face) of the snail 10 at position x ₃ , at which the snail 10 from a speed control to a pressure control. At the position x ₁ at which the dosing step ends, the exact position of the position x ₃ at which the speed control is switched from speed control to pressure control can not be determined, and hence the average value X _{3 of} the position x _{3 is used} for each injection molding operation , Since this is the case, the rotation phase θ _{3 of} the screw becomes 10 represented by the following equation (6).

Similarly, θ ₄ denotes as in (b) the 5 is shown, the rotational phase of the screw 10 at the intersection between the plane of the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 (yz plane at the position where x = b) and the front end 14f the worm-gear top of the snail 10 at position x ₄ , at which the snail 10 during the Nachdruckhalteschritts furthest advanced. Here, f '(θ ₄ ) of the equation (2) at the time point where θ = θ ₄ is the coordinates of the intersection between the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 (xy plane at the position where x = b) and the front end 14f the worm-gear top of the snail 10 at the position x ₄ , on. At the position x ₁ of completion of the metering step, it is not possible to know the exact position of the position x _{4 of} the furthest advance of the screw 10 during the Pressure hold step, and thus the average value X ₄ at position x _{4 is used} for each injection molding operation. However, since this is the case, the rotational phase angle θ _{4 of} the worm becomes 10 represented by the equation (7).

The following equation (8) gives the range of the leading end 14f the worm-gear top of the snail 10 at, the yz plane at x = b in the forward movement or the feed of the screw 10 during the hold pressure step.

6 Fig. 12 is a diagram for explaining the area of the front end 14f the worm gear top of the snail, for which there is the possibility of plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is clamped in the event that it is assumed that the plastic pellets size h at the position x = x ₄ for the furthest forward movement of the screw 20 during the holding pressure step.

Herein, h is the maximum total length of the plastic pellets. As in 6 shown, it is to ensure that no plastic pellets between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 at the position x _{4 of} the furthest forward movement of the worm 10 be clamped during the post-pressure holding step, an area from the plane of the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 (yz plane at the point x = b) to the front end 14f the worm-gear top of the snail 10 which has been shortened to a plane (yz plane at the position x = b - h) shortened by a distance h in the direction of the x-axis. Herein, θ ₄ 'denotes the rotation phase of the screw 10 at the intersection of the front end 14f the worm-gear top of the snail 10 and the plane (yz plane at the position x = b-h) reduced by a distance h in the direction of the x-axis from the plane (yz plane at the position x = b) of the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 at the position x _{4 of} the furthest forward movement of the worm 10 during the hold pressure step. Here, f '(θ ₄ ') from the equation (2) with θ = θ ₄ 'gives the coordinates of the intersection between the front end 14f the worm-gear top of the snail 10 and the plane (yz plane at the position x = b - h) reduced by a distance h in the direction of the x-axis from the plane (yz plane at the position x = b) of the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 at the position x _{4 of} the furthest forward movement of the worm 10 during the hold pressure step. The following equation (9) has been obtained from equation (7).

Accordingly, the following equation (10) gives the range of the rotational phase θ of the screw 10 on, at the plastic pellets between the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 and the helix 12 the screw after advancing the screw 10 can be pinched during the post-holding step.

It becomes possible to determine on the basis of the range of the rotation phase θ as the front end 14f the worm-gear top of the snail 10 the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 happens. The following equation (11) has been derived taking into account the range of θ 'at ρ.

7 FIG. 12 is a figure for explaining a projection of a predicted value at an end position (x = x ₁ ) of the metering step on the yz plane at the position where x = b in an area where there is a possibility that the front one The End 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm gear top and the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 during the forward movement of the screw 10 is trapped during the post-pressure holding step.

To distinguish here, whether there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the opening leading edge of the task opening 26 for injection molding material and the front end 14f the worm gear top is pinched, it is sufficient at the location of the front end 14f the worm-gear top of the snail 10 , which is the yz plane at the position where x = b, and the yz plane at the point where x = b - h, to the yz plane at the point where x = b, like this in 7 is shown, to project and to check if the projected point of the front end 14f the worm gear top, the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 overlaps or not, so d ≤ s ≤ e.

(1) If 2π ≤ ρ

8th Fig. 12 is an illustration for explaining a position of the front end 14f the worm-gear top of the snail 10 in the yz plane at the position where x = b, advancing during the post-pressure holding step in the case where θ satisfies the condition 2π ≤ ρ (as described above, where ρ is a range of the rotational phase θ '). of the worm gear 12 the snail 10 in which plastic pellets between the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 and the front end 14f the worm-gear top of the snail 10 can be trapped). The one with the reference number 150 marked area with oblique hatching in 8th is an area in which there is an area (ρ) of θ and the task opening 26 for injection molding material of the cylinder 20 overlap.

8th places a projection on the yz plane at x = b at a location on the front end 14f the worm-gear top of the snail 10 which intersects the yz plane at x = b and the yz plane at x = b-h.

In this case, the snail moves 10 by a distance equal to or greater than one (1) pitch of the flight 12 is, and consequently the front end happens 14f the worm gear top necessarily the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 , An injection molding process that makes it the snail 10 however, to advance by a distance equal to or greater than one (1) pitch in the post-holding step requires less precision than precision injection molding due to the reduction in holding pressure due to the jamming of plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is affected in the holding pressure step. Consequently, it is not necessary to use the function of preventing pinching of plastic material according to the present invention for such injection molding in the injection molding machine.

(2) If 2π - (e - d) ≤ ρ ≤ 2π

9A to 9D are all representations to explain the location of the front end 14f the worm-gear top of the snail 10 in the yz plane, at the point where x = b, follows when the snail 10 during the post-pressure holding step, for a case where ρ satisfies the condition at 2π - (e - d) ≦ ρ ≦ 2π. The area in 9A to 9D obliquely hatched and with the reference numeral 152 is an area in which a range (ρ) of θ and the feed opening 26 for injection molding material of the cylinder 20 overlap each other. 9A to 9D make projections of the location of the front end 14f the worm-gear top of the snail 10 to the yz plane at x = b, which intersects the yz plane at x = b and yz at x = b - h. The projections can be divided into four in 9A to 9D represented cases are subdivided on the basis of the relation of the position of f '(θ ₃ ) and f' (θ ₄ '). In all cases, it turns out that there is a possibility that the front end 14f The worm gear top causes plastic between the front end 14f the worm gear top and the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 during the movement of the snail 10 from the position x ₃ (the position at which a speed control is changed over to a pressure control) to the position x ₄ (position of the largest feed of the worm 10 during the post-pressure holding step). It has also been found that the numeral 152 provided area, and this is the area in which the overlap between the area (ρ) of θ and the task opening 26 for injection molding material of the cylinder 20 is smallest when f '(θ ₃ ) and f' (θ ₄ ') in the in 9A positional relationship are located. It has also been found that in the case of 9B to 9D shown positional relationship can be made such a control that the reference numeral 152 is made as small as possible, that is the overlap area between the area (ρ) of θ and the feed opening 26 for injection molding material of the cylinder 20 in which you look at the snail 10 until the in 9E or 9F turns the position shown. An example of a special method for the rotation control of the screw 10 will be described below with reference to the second embodiment.

(3) When 0 ≦ ρ ≦ 2π - (e - d)

10A and 10B are representations that show the places where the front end 14f the worm-gear top of the snail 10 in the yz plane at x = b follows while the snail 10 during the post-pressure hold step, in a case where ρ satisfies the condition 0 ≤ ρ ≤ 2π - (e - d). 10A FIG. 13 is a diagram showing a state before an avoidance operation, and FIG 10B Fig. 10 is a diagram showing a state after an avoidance process. The obliquely hatched and with the reference numeral 154 provided area in 10A is an area where there is an overlap of a range ρ of θ and the feed opening 26 for injection molding material of the cylinder 20 is present. 10A shows a projection of a point of the front end 14f the worm-gear top of the snail 10 , which intersects the yz plane at x = b, on the yz plane at x = b. 10A shows that there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm gear top and the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 during the movement of the snail 10 from position x ₃ (position of changeover from speed control to pressure control) to position x ₄ (position of the furthest advance of the worm 10 during the post-pressure holding step).

10B shows, however, that a control can be carried out by rotation of the screw 10 in such a way that the front end 14f the worm-gear top of the snail 10 the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 did not happen at all.

In 11 an example is shown in which the control is made in such a way that the front end 14f the worm-gear top of the snail 10 the Opening leading edge of the task opening 26 for injection molding material of the cylinder 20 during the holding pressure step, by causing the screw to be caused 10 in an operation preceding the post-pressure holding step, in the case where there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is trapped during the post-pressure holding step. An example of a specific method for such a control will be explained later in the second embodiment.

• (1) Wenn cose ≤ cos(θ₃ + c₁) ≤ cosd und 0 ≤ sin(θ₃ + c₁) in einer Projektion des vorderen Endes 14f der Schneckengangoberseite der Schnecke 10, die die yz Ebene bei x = b und die yz Ebene bei x = b – h schneidet, auf die yz Ebene an der Stelle, an x = b erfüllt ist, dann ist ρ so wie es in 11 dargestellt ist.
• (2) Wenn cose ≤ cos(θ₄' + c₁) ≤ cosd und 0 ≤ sin(θ₄' + c₁) in einer Projektion des vorderen Endes 14f der Schneckengangoberseite der Schnecke 10, die die yz Ebene bei x = b und die yz Ebene bei x = b – h passiert, auf die yz Ebene, an der Stelle, an der x = b erfüllt ist, dann ist ρ so wie es in 13 dargestellt ist.
• (3) Wenn cose ≤ cos(θ₃ + c₁) ≤ cos(θ₄' + c₁) ≤ cosd, 0 ≤ sin(θ₃ + c₁) und 0 ≤ sin(θ₄' + c₁) in einer Projektion des vorderen Endes 14f der Schneckengangoberseite der Schnecke 10, die die yz Ebene bei x = b und die yz Ebene bei x = b – h passiert, auf die yz Ebene an der Stelle, an der x = b erfüllt ist, dann ist p so wie es in 15 dargestellt ist.
• (4) Wenn cos(θ₃ + c₁) ≤ cose und cosd ≤ cos(θ₄' + c₁) in einer Projektion des vorderen Endes 14f der Schneckengangoberseite der Schnecke 10, die die yz Ebene bei x = b und yz Ebene bei x = b – h passiert, auf die yz Ebene an der Stelle, an der x = b erfüllt ist, dann ist ρ so wie es in 17 dargestellt ist.
• (5) Wenn cose ≤ cos(θ₃ + c₁) ≤ cosd, sin(θ₃ + c₁) ≤ 0 und cosd ≤ cos(θ₄' + c₁) in einer Projektion des vorderen Endes 14f der Schneckengangoberseite der Schnecke 10, die die yz Ebene bei x = b und yz Ebene bei x = b – h passiert, auf die yz Ebene, an der Stelle, an der x = b erfüllt ist, dann ist ρ so wie es in 19 dargestellt ist.
• (6) Wenn cose ≤ cos(θ₄' + c₁) ≤ cosd, sin(θ₄' + c₁) ≤ 0 und cos(θ₃ + c₁) ≤ cose in einer Projektion des vorderen Endes 14f der Schneckengangoberseite der Schnecke 10, die die yz Ebene bei x = b und yz Ebene bei x = b – h passiert, auf die yz Ebene an der Stelle, an der x = b erfüllt ist, dann ist ρ so wie es in 21 dargestellt ist.

Further, a distinction is made below the position f '(θ ₃ ) and f' (θ ₄ ') for the individual cases (1) to (6). The front end 14f the worm-gear top of the snail 10 happens the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 if ρ satisfies one of the conditions (1) to (6).

• (1) If cose ≤ cos (θ ₃ + c ₁ ) ≤ cosd and 0 ≤ sin (θ ₃ + c ₁ ) in a projection of the front end 14f the worm-gear top of the snail 10 , which intersects the yz plane at x = b and the yz plane at x = b - h, satisfies the yz plane at the point where x = b, then ρ is as it is in 11 is shown.
• (2) If cose ≤ cos (θ ₄ '+ c ₁ ) ≤ cosd and 0 ≤ sin (θ ₄ ' + c ₁ ) in a projection of the front end 14f the worm-gear top of the snail 10 , which passes the yz plane at x = b and the yz plane at x = b - h, to the yz plane, at the point where x = b is satisfied, then ρ is as it is in 13 is shown.
• (3) If cose ≤ cos (θ ₃ + c ₁ ) ≤ cos (θ ₄ '+ c ₁ ) ≤ cosd, 0 ≤ sin (θ ₃ + c ₁ ) and 0 ≤ sin (θ ₄ ' + c ₁ ) in FIG a projection of the front end 14f the worm-gear top of the snail 10 , passing the yz plane at x = b and the yz plane at x = b - h, to the yz plane at the point where x = b is satisfied, then p is as it is in 15 is shown.
• (4) If cos (θ ₃ + c ₁ ) ≤ cose and cosd ≤ cos (θ ₄ '+ c ₁ ) in a projection of the front end 14f the worm-gear top of the snail 10 , passing the yz plane at x = b and yz plane at x = b - h, to the yz plane at the point where x = b is satisfied, then ρ is as it is in 17 is shown.
• (5) If cose ≤ cos (θ ₃ + c ₁ ) ≤ cosd, sin (θ ₃ + c ₁ ) ≤ 0, and cosd ≤ cos (θ ₄ '+ c ₁ ) in a projection of the front end 14f the worm-gear top of the snail 10 , passing the yz plane at x = b and yz plane at x = b - h, to the yz plane, at the point where x = b is satisfied, then ρ is as it is in 19 is shown.
• (6) If cose ≤ cos (θ ₄ '+ c ₁ ) ≤ cosd, sin (θ ₄ ' + c ₁ ) ≤ 0, and cos (θ ₃ + c ₁ ) ≤ cose in a projection of the front end 14f the worm-gear top of the snail 10 , passing the yz plane at x = b and yz plane at x = b - h, to the yz plane at the point where x = b is satisfied, then ρ is as it is in 21 is shown.

In the case (2) and when one of the conditions (1) to (6) is satisfied in the case (3), there is a possibility that the front end 14f The worm gear top causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 due to a forward movement of the screw 10 is trapped during the post-pressure holding step. In this case, the speed control is performed by interrupting the pressure control in an interval x = x ₃ to x ₄ of the post-pressure holding step. Herein, examples of (a) and (b) examples of the speed control of the worm 10 during the hold pressure step in such a case. The equations for the shape of the flight will be for each specification number of the screw 10 stored in the injection molding machine in the form of a data set in a database. When replacing the screw 10 the specification number of the replacement screw becomes against another of a different shape 10 read from the database.

(a) Velocity control of the screw 10 in the pressure holding step (constant speed)

The speed control of the screw 10 is executed at a previously set speed V _A after the worm has reached the position x ₃ (position at which a speed control is switched to a pressure control) until the previously set end of the holding pressure time.

(b) Speed control of the worm 10 during the post-pressure holding step (average speed calculation).

This applies to cases of holding back which have been previously set over many work steps. For each injection molding operation, the position x ₃ (position of switching from the speed control to the pressure control) and the position x ₄ (position of the furthest advance of the worm 10 during the holding pressure step) of the screw 10 together with the times t ₃ , t ₄ at which these positions x ₃ , x _{4 are} reached, recorded in a case where the pressure control is made such that the front end 14f the worm-gear top of the snail 10 the yz plane at x = b and yz plane at x = b-h does not pass in the post-pressure holding step, and averages X ₃ , X ₄ , T ₃ and T _{4 of} these positions x ₃ and x _{4 of} the screw 10 and the times t ₃ , t ₄ at which the positions are reached are calculated. These timings t _b1 , t _b2 , t _b3 ,..., T _{bn of} the _{hold pressure switching} at each stage, for each injection molding operation, and the positions x _b1 , x _b2 , x _b3 , x _{bn of} the worm 10 at these times are recorded and the averages thereof T _b1 , T _b2 , T _b3 , T _bn and X _b1 , X _b2 , X _b3 , X _bn are calculated.

From positions X ₃ to X _{4 of} the screw 10 the speed control of the latter takes place at a speed V _B , which results from equation (12) below. In a case where that Containing a single work routine and / or a single speed holding, the calculation is simplified, because then the speed control of the screw 10 at a speed V _B according to the following equation (13), which is a Nachdruckhaltestartposition (position at which is switched from a speed control to a pressure control) and the Druckhalteendposition (position of the furthest advancing the worm 10 during the hold pressure step). Further, random measurement points may be set in the interval x = x ₃ to x ₄ instead of hold pressure changeover positions preset for each operation, so that the speed can be calculated by recording the times at which these measurement points are passed. As long as one does not obtain a result of the injection molding in which the pressure control is performed such that the front end 14f the worm-gear top of the snail 10 not the yz plane at x = b and the yz plane at x = b-h in the post-pressure holding step, is from the beginning of the continuous injection molding to the speed control (constant speed) of the screw 10 in the post-pressure holding step (a) as proposed above.

2nd embodiment

As previously described in connection with the first embodiment, the top of the flight will become 12 the snail 10 at a rotation angle and a position in the back and forth movement direction thereof from the opening leading edge of the feed opening 26 for spray material of the cylinder 20 distinguished by describing in the form of equations, the shape of the flight 12 the snail 10 and the shape of the opening end edge of the rectangular task opening 26 for injection molding material.

(4) When 2π≤p

As described for the first embodiment above, injection molding requires the screw 10 is advanced by a distance of one or more than one pitch in the post-pressure holding step, a lower precision. Consequently, in such an injection molding operation, it is not necessary to employ the function for preventing the pinching of plastic material according to the present invention in the injection molding machine.

(5) When 2π - (e - d) ≦ p ≦ 2π

As described above in (2) for the 1st embodiment, there are four conceivable cases according to the 9A to 9D based on the positional relationships of f '(θ ₃ ') and f '(θ ₄ '). In a case where f '(θ ₃ ) and f' (θ ₄ ') are in the positional relationship that in 9A is shown, takes the region indicated by the reference numeral 152 and which is a section in which the range (ρ) of θ 'and the feed opening 26 for injection molding material of the cylinder 20 overlap, a minimum value and thus becomes a rotation (angle) control of the screw 10 not executed. In case of 9B to 9D For example, the control may be performed in a manner that is denoted by the reference numeral 152 provided region in which part of the range (ρ) of θ 'and the feed opening 26 for injection molding material of the cylinder 20 overlap, thereby taking a minimum value by controlling the rotation of the screw 10 up to the in 9E and 9F shown positions causes. In the in 9A The positional relationships of f '(θ ₃ ) and f (θ ₄ ') shown in Fig. 10 are the relationships cose ≤ cos (θ ₄ '+ c ₁ ) ≤ cos (θ ₃ + c ₁ ) ≤ cosd, 0 ≤ sin (θ ₃ + c ₁ ) and 0 ≦ sin (θ ₄ '+ c ₁ ), and thus, a rotation (angular) control of the worm becomes 10 executed when the above relationships are not met. Regarding the direction of rotation, in which the worm is caused to rotate about its central axis, and the degree of rotation of the worm 10 will be the smallest amount of rotation from the amount of rotation to which the snail 10 is normally caused to rotate back and forth, so that the conditions cos (θ ₃ + c ₁ ) = cosd and sin (θ ₃ + c ₁ ) = are at the in 9E shown position, and selected from the amount of rotation to the the worm 10 in the normal direction or in the opposite direction, so that the conditions cos (θ ₄ '+ c ₁ ) = cose and sin (θ ₄ ' + c ₁ ) = sine at the in 9F shown position are met.

(6) When 0 ≦ ρ ≦ 2π - (e - d)

In the case described one of cases (1) to (6) in (3) of the first embodiment, the control is executed by the screw 10 is caused to rotate while the worm from the position x ₁ (position at which the worm 10 stops the dosing step of the molten resin and stops rotating) is moved to the position x ₃ (position of switching from speed control to pressure control), so that the front end 14f the worm gear top 14 the snail 10 the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 did not happen at all.

12A and 12B are illustrations for explaining conceivable positions of ρ in the case of the condition (1) and for explaining an example of a prohibiting operation. The by the reference 156 designated obliquely hatched area in 12A returns an area in which the task opening 26 for injection molding material and the rotational phase range (ρ) of θ 'of the worm gear of the screw 10 for which there is a possibility that plastic pellets between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for the injection molding material of the cylinder 20 while advancing the screw 10 is trapped during the post-pressure holding step. 12A FIG. 12 is a diagram showing a state before an avoidance operation and FIG 12B Fig. 10 is a diagram showing a state after an avoidance process.

14A and 14B are illustrations for explaining conceivable positions of ρ in the case of the condition (2) and for explaining an example of an avoidance operation. The one with the reference number 158 designated area which in 14A is represented by oblique hatching corresponds to an area in which a range (ρ) of θ 'and the feed opening 26 for injection molding overlap each other. 14A Fig. 13 is a diagram for explaining a state before an avoidance process and 14B Fig. 12 is a diagram for explaining a state after an avoidance process.

16A and 16B are illustrations for explaining conceivable positions of ρ in the case of the condition (3) and for explaining an example of an avoidance operation. The one with the reference number 160 provided area in 16A is represented by oblique hatching, represents an area in which a range (ρ) of θ 'and the feed opening for the injection molding material overlap each other.

16A Fig. 13 is a diagram for explaining a state before an avoidance process and 16B Fig. 12 is a diagram for explaining a state after an avoidance process.

18A and 18B are illustrations for explaining conceivable positions of ρ in the case of a condition (4) and for explaining an example of an avoidance operation. The one with the reference number 162 provided area in 18A represented by oblique hatching, reflects an area, in which a range (ρ) of θ 'and the feed opening 26 overlap each other for the injection molding material. 18A FIG. 13 is a diagram showing a state before an avoidance operation, and FIG 18B Fig. 10 is a diagram showing a state after an avoidance process.

20A and 20B are representations for explaining conceivable positions of ρ in the case of a condition (5) and for explaining an example of an avoidance operation. The one with the reference number 164 provided area in 20A indicated by oblique hatching, represents an area in which a range (ρ) of θ 'and the feed opening 26 for injection molding overlap each other. 20A FIG. 12 is a diagram showing a state before an avoidance operation and FIG 20B Fig. 10 is a diagram showing a state after an avoidance process.

22A and 22B are representations for explaining conceivable positions of ρ in the case of a condition (6) and for explaining an example of an avoidance operation. The one with the reference number 166 provided area in 22A represented by oblique hatching, represents an area in which a range (ρ) of θ 'and the feed opening 26 overlap each other for the injection molding material. 22A FIG. 13 is a diagram showing a state before an avoidance operation, and FIG 22 Fig. 10 is a diagram showing a state after an avoidance process.

Examples of avoidance operations such that the front end 14f the worm-gear top of the snail 10 the opening end edge of the task opening 26 for injection molding material of the cylinder 20 not at all, are shown for the above-described conditions (1) to (6) in FIG 12 (according to condition (1)), 14 (according to condition (2)), 16 (according to condition (3)), 18 (according to condition (4)), 20 (according to condition (5)) and 22 (according to condition (6)). Regarding the direction in which the snail 10 is rotated about its central axis, and the amount of rotation of the screw 10 At this time, the least possible out of the rotation amount is chosen to the the worm 10 is rotated to perform a normal rotation (reverse rotation in the yz plane) so that the conditions cos (θ ₃ + c ₁ ) = cosd and sin (θ ₃ + c ₁ ) = and the rotation amount at which the worm 10 is rotated to perform an opposite rotation (normal rotation in the yz plane) so that the conditions cos (θ ₄ '+ c ₁ ) = cose and θ ₄ ' + c ₁ ) = sine are satisfied.

In a case, none of the conditions ( 1 ) to (6), the worm gear top of the worm passes 10 the opening end edge of the task opening 20 for injection molding material of the cylinder 20 not at all, and consequently, no rotation control is required after the dosing step is completed. The equations for the helical flight shape for each screw serial number 10 in the injection molding machine are stored in the form of database entries, so that after an exchange of screws with a different shape, the specification number or number of the exchange screw can be read from the database.

3rd embodiment

After the above description of the first embodiment, an explanation will now be given with reference to the accompanying drawings for a case where the feed opening for injection molding material of the cylinder is rectangular and the screw 10 is moved back during the Nachdruckhalteschritts.

23 is a representation for explaining the worm gear 12 the snail 10 and an opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 ,

In 23 denotes the reference numeral 180 an enlarged partial section for explaining a place where the screw bore of the cylinder 20 with the rectangular task opening 26 for injection molding material that is in the filler block 24 and the cylinder 20 are provided. The reference number 182 denotes a representation of the task opening 26 for the injection molding viewed from above the rectangular task opening 26 for injection molding material. The reference number 184 in this figure denotes a location where there is a possibility that plastic pellets between the back 14r the worm gear top of the worm gear 12 the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 after moving back the screw 10 be trapped during the post-pressure holding step. The reference number 186 is a diagram for explaining a shape of the back 14r the worm-gear top of the snail 10 , The reference number 187 in the figure denotes a shape of the opening trailing edge of the feed opening 26 for injection molding of the cylinder 20 and the reference numeral 188 Fig. 12 is an illustration for explaining a shape of the rear end 14r of the worm gear 12 the snail 10 ,

As in 23 shown are the position of the rear end 14r the worm-gear top of the snail 10 at a rotation angle and a position in the front and rear direction thereof with respect to the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 distinguished by reproduction in the form of equations of the shape of the screw flight 12 the snail 10 and the shape of the opening trailing edge of the task opening 26 (rectangular shape) for injection molding material. Determining the position of the screw 10 in the forward and backward directions as well as the determination of the angle of rotation of the worm 10 are well-known operations in the technical field herein, and an explanation thereof will be omitted.

24 Fig. 4 is a diagram for explaining the manner in which the location of the trailing end 14r the worm-gear top of the snail 10 and the opening trailing edge of the rectangular feed opening 26 for injection molding material of the cylinder 20 in the form of equations.

First, xyz coordinates are given, as in 24 is shown. The y axis and the z axis are set in such a way that the central axis 16 the snail 10 lying on the x axis. R is the distance of the x axis to the back 14r the worm-gear top of the snail 10 , The coordinate origin of the xyz coordinates is set in such a manner that the starting point of the helix of the front end of the worm gear top of the worm 10 at x = 0, y = R, z = 0, ie in a state in which the screw 10 in the most advanced position. The width of the worm gear top is given as L (L> 0). In this case, the equation for the helix of the trailing end 14r the worm-gear top of the snail 10 in the form of the following equation (14). Here, λ (0 ≦ λ ≦ 2nπ) means the rotation phase of the screw 10 and n is a natural number.

In addition, a return path X from the furthest advanced position of the screw 10 and adds a rotation angle c. As already described above, the most advanced position of the worm becomes 10 used as the source, so the snail 10 can only be moved back and thus X ≤ 0. The normal direction of rotation of the screw 10 is clockwise, viewed from the side of the cylinder with the injection port, and is an opposite direction of rotation in the yz plane. Therefore, c ≦ 0. Thus, the equation for the helix is the backside 14r the worm-gear top of the snail 10 in the returned position X by the following equation (15).

The opening trailing edge of the feed opening 26 for the injection molding material of the cylinder 20 is described by a mathematical equation as indicated below. The origin is given in such a way that it is identical with the origin O of the xyz coordinates, at which the shape of the helical flight 12 the snail 10 is represented in the form of an equation. The opening trailing edge of the feed opening 26 for the sprayed material lies in a plane which is parallel to the yz plane at a distance from the origin O by a distance x = j. The phases of the segment that both ends of the opening trailing edge of the task opening 26 for injection molding material and the x-axis (the with the center axis of the cylinder and the central axis 16 the snail 10 match) are d and e. Since this is the case, the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 represented by the following equation (16).

The intersection of the equation (15) and the equation (16) on the x-axis is represented by the equation (17). This intersection is the position of the back end 14r the snail edge top of the snail 10 at the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 ,

Here, x _{1 means} the position at which the worm 10 the metering of the molten plastic stops and also stops its rotation. The position x ₂ is the position to which the worm 12 is moved back from the aforementioned position in the post-pressure holding step. Further, x ₃ denotes the position at which the worm 10 thereafter, switching from the speed control to the pressure control in an injection operation, and x ₄ denotes the position of the maximum forward movement of the worm during the post-pressure holding step. x ₀ is here the starting position for dosing in a next injection process. These positions x ₁ , x ₂ , x ₃ , x ₄ , x _{0 of} the screw 10 can be measured and recorded by known methods. The positions x ₁ , x ₂ , x ₃ , x ₄ , x _{0 of} the screw 10 for each spraying operation are recorded and averaged, and the average values thereof X ₁ , X ₂ , X ₃ , X ₄ and X ₀ are used. Instead of X _1, X _2, X _3, X ₄ and X ₀ mean values (mean values of motion) for n injection operations can be (where n is a natural number) that precede the current injection process under indirectly. Assuming the moving average values as n = 1, the positions x ₁ , x ₂ , x ₃ , x ₄ , x _{0 of} the worm can also be assumed 10 be used at a the previous injection process by an injection preceding injection. For the first injection process, which does not have an immediately preceding injection process, a predetermined value of a position of the screw 10 in which the dosing was complete, used as the value X ₁ , a predetermined value of the position at which the pressure reduction is complete and to which the screw 10 can be used as X ₂ , a predetermined value of the position at which the screw is moved back in the holding pressure step 10 from a speed control to a pressure control, may be used as the value X ₃ , the origin O of the worm 10 can be used as X ₄ and X ₀ = X ₃ .

At least the time of the furthest forward movement of the snail 10 during the post-holding step and the time of commencement of dosing for the next injection are presetted beforehand. The relationships according to the following equations (18) are valid between the positions x ₁ , x ₂ , x ₃ , x ₄ , x _{0 of} the screw 10 for each injection and between X ₁ , X ₂ , X ₃ , X ₄ and X ₀ , by recording and averaging the position x ₁ , x ₂ , x ₃ , x ₄ , x _{0 of} the screw 10 be obtained for each injection process. x ₂ ≤ x ₁ ≤ x ₀ ≤ x ≤ ₄ 0 ≤ X ₂ ≤ X ₁ X ₀ ≤ X ≤ ₄ 0 (18)

c _{1 also} denotes a rotation angle of the worm 10 at position x ₁ , where the worm 10 finished the metering process for the molten plastic mass and completed its rotation. Next is a description of a specific method for determining whether the back end 14r the worm-gear top of the snail 10 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 happens and whether or not plastic pellets when moving back the screw 10 be clamped thereby by using X ₁ , X ₂ , X ₃ , X ₄ , X ₀ and c ₁ as well as the above-mentioned equation (14), equation (15), equation (16), equation (17) and equation (18) showing the positional relationship between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 describe.

25 is a diagram for explaining the location of the rear end 14r the worm-gear top of the snail 10 representing the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 as the worm moves back from position x = x _{4 of} the furthest advance of the worm during the hold-pressure holding step to the start position of dosing x = x ₀ .

Usually the auger rotates 10 from the completion of the dosing step until the beginning of the next dosing step. Therefore, the rotation angle c _{1 of} the worm 10 at the position x ₁ for the completion of the dosing step, the angle of rotation of the screw 10 at the position x ₄ for the furthest advance of the worm 10 during the post-pressure holding step and at the starting position x ₀ for the next dosing step.

As with (a) the 25 is shown, λ ₄ denotes the rotational phase of the screw 10 at the intersection between the opening trailing edge (yz plane at x = j) of the feed opening 26 for injection molding material of the cylinder 20 and the back end 14r the worm-gear top of the snail 10 at the position x _{4 of} the furthest advance of the worm 10 during the hold pressure step. Here, g '(λ ₄ ) of Equation (15) at time λ = λ ₄ gives the coordinates of the intersection between the opening trailing edge yz plane at the position where x = j and the output port 26 for injection molding material of the cylinder 20 , and the rear end 14r the worm-gear top of the snail 10 at the position x _{4 of} the furthest possible forward movement of the screw 10 during the hold pressure step. At the position x ₁ of completion of the metering step, it is not possible to know the exact position x _{4 of} the furthest advance of the screw 10 during the post-holding step, and hence the average X ₄ of position x _{4 is used} for each injection. Since this is the case, the rotational phase λ _{4 of} the screw 10 represented by the following equation (19).

Likewise, as in (b) the 25 is shown, λ _0, the rotation phase of the screw 10 at the intersection between the opening trailing edge (yz plane at x = j) of the feed opening 26 for injection molding material of the cylinder 20 and the back end 14r the worm-gear top of the snail 10 at the next start position x ₀ for the dosing step. Here, g '(λ ₀ ) from equation (15) at the time λ = λ ₀ gives the coordinates of the intersection between the opening trailing edge (yz plane at x = j) of the feed opening 26 for injection molding material of the cylinder 20 and the rear end 14r the worm-gear top of the snail 10 at the next start position x ₀ for the dosing step. At the position x ₁ for the completion of the dosing step, it is not possible to determine the exact position of the next start position x ₀ for the dosing step, and consequently the average value X ₀ for x _{0 is used} for each injection. Since this is the case, the rotational phase λ _{0 of} the screw 10 represented by the following equation (20).

The following equation (21) gives the range of the rear end 14r the worm-gear top of the snail 10 indicating the yz plane at x = j during the backward movement of the worm 10 during the hold pressure step.

26 Fig. 12 is a diagram for explaining the area of the rear end 14r the worm-gear top of the snail 10 , for which there is a possibility that plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 in a case where it is assumed that plastic pellets have the size h at the starting position x = x _{0 of} the metering step, is pinched.

H here means the maximum total length of the plastic pellets. To ensure that no plastic pellets between the screw flight 12 the snail 10 and a plane (yz plane at x = j) of the opening trailing edge of the feed opening 26 for the injection molding material of the cylinder 20 on the next start, to be clamped at the position x ₀ of the metering step, it is necessary to make an area from the plane of the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 to the far end 14r the worm-gear top of the snail 10 if this has moved down to a plane (yz plane at x = j + h) reduced by a distance h in the direction of the x-axis, take into account how this is done in 26 is shown. Here, λ ₀ 'denotes the rotational phase of the screw at the intersection between the rear end 14r the worm-gear top of the snail 10 and the plane (yz plane at x = j + h), in which the back end 14r the worm-gear top of the snail 10 at a distance h in the direction of the x-axis from the plane (yz plane for which x = j holds) from the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 located. Here, g '(λ ₀ ') of the equation (15) at the time when λ = λ ₀ 'gives the coordinates of the intersection between the rear end 14r the worm-gear top of the snail 10 and a plane (yz plane for which x = j + h) reduced by a distance h in the direction of the x-axis from the plane (yz plane for which x = j) of the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 at the next start position x _{0 of} the dosing step again. The following equation (22) has been obtained from the equation (20).

Accordingly, equation (23) gives the range of the rotational phase λ 'of the screw 10 again, where there is a possibility that plastic pellets between the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 and the back end 14r the worm-gear top of the snail 10 when moving back the snail 10 be trapped during a post-pressure holding step.

It thus becomes possible to determine on the basis of the range of λ 'as the trailing end 14r the worm-gear top of the snail 10 the opening trailing edge of the task opening 26 for injection molding material of the cylinder happens. The following equation (24) has been obtained considering the range of λ 'as η.

27 Fig. 12 is a diagram for explaining the projection of a predicted value at the position (x = x ₁ ) of the completion of a dosing step on the yz plane for which x = y, for the range for which there is a possibility that the trailing end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 when moving back the snail 10 is trapped during the post-pressure holding step. To see if there is a possibility that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 is clamped for injection molding material, it is sufficient, a point of the rear end 14r the worm-gear top of the snail 10 , which holds the yz plane for which x = j, and the yz plane for which x = j + h holds, as happens in 27 is shown projecting onto the yz plane, for which x = j, and checking whether or not the projection (projected location of the trailing end 14r of the Helix top of the snail 10 ) the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 overlaps so that d ≤ s ≤ e.

(7) If 2π ≤ η

28 is a diagram for explaining a point where the rear end 14r the worm-gear top of the snail 10 the yz plane, for which x = j holds, follows while the snail is 10 during the post-pressure holding step, in a case where η satisfies the condition 2π ≦ η (as described above), η denotes a range of the rotational phase λ 'of the screw 10 at the plastic pellets between the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 and the back end 14r the worm-gear top of the snail 10 ) can be trapped. The one with the reference number 190 designated, in 28 obliquely hatched area is an area in which a range (η) of λ 'and the feed opening 26 for injection molding material of the cylinder 20 overlap.

28 represents a projection of the location of the back end 14r the worm-gear top of the snail 10 That is, the yz plane to which x = j holds and the yz plane to which x = j + h holds pass to the yz plane for which x = j.

In this case, the snail moves 10 a distance equal to or greater than a pitch of the flight 12 is back, and consequently the back end happens 14r the worm gear top necessarily the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 , An injection molding process in which the snail 10 moving back the distance of one (1) grade or more in the post-holding step requires less precision than precision injection molding which is affected by blocking a post-pressure holder reduction caused by pinching plastic between the rear end 14a the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is effected in the Nachdruckhalteschritt. As a result, it is not necessary for such injection molding to apply the function of avoiding pinching of plastic material according to the present invention in the injection molding machine.

(8) When 2π - (e - d) ≤ η ≤ 2π

29A to 29D are each representations to explain the location of the rear end 14r the worm-gear top of the snail 10 on the yz plane, for which x = j, follows when the snail 10 during the pressure hold step, for a case where η satisfies the condition 2π - (e - d) ≦ η ≦ 2π. The by the reference 192 designated, in 29A to 29D obliquely hatched area is a part in which a range (η) of λ 'and the feed opening 26 for injection molding material of the cylinder 20 overlap. 29A to 29D show projections of the place of the back end 14r the worm-gear top of the snail 10 that the yz plane for which x = j holds, and the yz plane for which at x = j + h, pass to the yz plane for which x = j holds. The projections can be subdivided into four regions based on the positional relationships of g '(λ ₄ ) and g' (λ ₀ ') 29A to 29D are shown. In all cases it was found that there is a possibility that the rear end 14r the worm gear top causes plastic to be between the rear end 14r the worm gear top and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 during the movement of the snail 10 from position x ₄ (position of the furthest forward movement of the worm 10 during the post-holding step) to the position x ₀ (start position for the dosing step of the next injection). It has also been found that the reference numeral 192 designated area - this is the portion where the overlap between the area (η) of λ 'and the feed opening 26 for injection molding material of the cylinder 20 is lowest when g '(λ ₄ ) and g' (λ ₀ ') are in the in 29A positional relationship are located. It has further been found that in the case of positional relationship 29B to 29D a control can be made to the with the reference numeral 192 to keep the designated area as small as possible - this is the area of overlap between the area (η) and λ 'and the feed opening 26 for injection molding material of the cylinder 20 - that causes the snail 10 up to the in 29E or 29F rotated position shown. An example of a special method for controlling the rotation of the screw 10 will be described later for the fourth embodiment.

(9) When 0 ≦ η ≦ 2π - (e - d)

30A and 30B are representations that reflect the location of the back end 14r the worm-gear top of the snail 10 in the yz plane, for which x = j, when moving back the screw 10 in the post-pressure holding step, in the case where η satisfies the condition 0 ≦ η ≦ 2π - (e - d).

30A FIG. 12 is a diagram showing a state before an avoidance operation and FIG 30B Fig. 10 is a diagram illustrating a state after an avoidance process. The in 30A with the reference number 194 provided obliquely hatched area is a section in which a range (η) of λ 'and the feed opening 26 for injection molding material of the cylinder 20 overlap. 30A shows a projection of the location or the location of the rear end 14r the worm-gear top of the snail 10 , which is the yz plane for which x = j and the xz plane for which x = j + h holds, to the yz plane for which x = j. 30A lets realize that there is a possibility that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm gear top and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 during the movement of the snail 10 from position x ₄ (position at which the worm 10 has been advanced furthest during the hold-pressure holding step) to position x ₀ , start position for the dosing step of the next injection process).

30B shows, however, that control by rotation of the worm 10 can be made in such a way that the rear end 14r the worm-gear top of the snail 10 the opening trailing edge of the task opening 26 of the cylinder 20 did not happen at all.

In 2 an example is shown in which the control is carried out in such a way that the rear end 14r the worm-gear top of the snail 10 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 during the holding pressure step therefore does not happen because the screw 10 is caused to be rotated at an earlier stage before the post-holding step, in a case where there is otherwise a possibility that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm-gear top and the task opening 26 for injection molding material of the cylinder 20 is trapped during the post-pressure holding step. An example of a special method for controlling the rotation of the screw 10 will be explained in the following 4th embodiment.

• (7) Wenn cose ≤ cos(λ₀' + c₁) ≤ cosd und 0 ≤ sin(λ₀' + c₁) in einer Projektion des hinteren Endes 14r der Schneckengangoberseite der Schnecke 10, die die yz Ebene, für die x = j gilt, und die yz Ebene, für die x = j + h gilt, auf die yz Ebene, für die x = j gilt, passiert, dann nimmt η den in 3 dargestellten Wert an. 31 ist eine Darstellung zur Erläuterung, dass g'(λ₀'), projiziert auf die yz Ebene, für die x = j gilt, ein Fall von (7) ist, für den cose ≤ cos(λ₀' + c₁) ≤ cosd und 0 ≤ sin(λ₀' + c₁) erfüllt ist.
• (8) Wenn cose ≤ cos(λ₄ + c₁) ≤ cosd und 0 ≤ sin(λ₄ + c₁) in einer Projektion des hinteren Endes 14r der Schneckengangoberseite der Schnecke 10, die die yz Ebene, für die x = j gilt, und die yz Ebene, für die x = j + h gilt, auf die yz Ebene, für die x = j gilt, passiert, dann nimmt η den in 33 dargestellten Wert an. 33 ist eine Darstellung zur Erläuterung einer Instanz, an der g'(λ₀) projiziert auf die yz Ebene, für die x = j gilt, der Bedingung (8) entspricht, bei der cose ≤ cos(λ₄ + c₁) ≤ cosd und 0 ≤ sin(λ₄ + c₁).
• (9) Wenn cose ≤ cos(λ₀' + c₁) ≤ cos(λ₄ + c₁) ≤ cosd, 0 ≤ sin(λ₀' + c₁), 0 ≤ sin(λ₄ + c₁) in einer Projektion des hinteren Endes 14r der Schneckengangoberseite der Schnecke 10, die die yz Ebene, für die x = j gilt, und die yz Ebene, für die x = j + h gilt, auf die yz Ebene, für die x = j gilt, passiert, nimmt η den in 35 dargestellten Wert an. 35 ist eine Darstellung zur Erläuterung eines Falls, für den g'(λ₀) und g'(λ₄) projiziert auf die yz Ebene, für die x = j gilt, der Bedingung (9) entspricht, für die cose ≤ cos(λ₀' + c₁) ≤ cos(λ₄ + c₁) ≤ cosd, 0 ≤ sin(λ₀ + c₁) und 0 ≤ sin(λ₄ + c₁) ist.
• (10) Wenn cos(λ₀' + c₁) ≤ cose und cosd ≤ cos(λ₄ + c₁) in einer Projektion des hinteren Endes 14r der Schneckengangoberseite der Schnecke 10, die die yz Ebene, für die x = j gilt, und die yz Ebene, für die x = j + h gilt, auf die yz Ebene, für die x = j gilt, passiert, nimmt η den in 37 angegebenen Wert an. 37 ist eine Darstellung zur Erläuterung eines Falls, für den g'(λ₀') und g'(λ₄) projiziert auf die yz Ebene, für die x = j gilt, der Bedingung (10) entspricht, wo cos(λ₀' + c₁) ≤ cose und cosd ≤ cos(λ₄ + c₁).
• (11) Wenn cose ≤ cos(λ₀' + c₁) ≤ cosd, sin(λ₀' + c₁) ≤ 0 und cosd ≤ cos(λ₄ + c₁) in einer Projektion des hinteren Endes 14r der Schneckengangoberseite der Schnecke 10, die die yz Ebene, für die gilt, und die yz Ebene, für die x = j + h gilt, auf die yz Ebene, für die x = j gilt, passiert, nimmt η den in 39 dargestellten Wert an. 39 ist eine Darstellung zur Erläuterung eines Falls, für den g'(λ₀') und g'(λ₄) projiziert auf die Ebene, für die x = j gilt, der Bedingung (11) entspricht, für die cose ≤ cos(λ₀' + c₁) ≤ cosd, sin(λ₀' + c₁) ≤ 0 und cosd ≤ cos(λ₄ + c₁) erfüllt ist.
• (12) Wenn cose ≤ cos(λ₄ + c₁) ≤ cosd, sin(λ₄ + c₁) ≤ 0, cos(λ₀' + c₁) ≤ cose in einer Projektion des hinteren Endes 14r der Schneckengangoberseite der Schnecke 10 die yz Ebene, für die x = j gilt, und die yz Ebene, für die x = j + h gilt, auf die yz Ebene, für die x = j gilt, passiert, nimmt η den in 41 dargestellten Wert an. 41 ist eine Darstellung zur Erläuterung eines Falls, für den g'(λ₀') und g'(λ₄) projiziert auf die yz Ebene, für die x = j gilt, der Bedingung (12) entspricht, für die cose ≤ cos(λ₄ + c₁) ≤ cosd, sin(λ₄ + c₁) ≤ 0 und cos(λ₀' + c₁) ≤ cose erfüllt ist.

A distinction of the position of g '(λ ₄ ) and g' (λ ₀ ') is further divided into different cases (7) to (12) below. If λ satisfies one of the conditions (7) to (12), there is a possibility that the worm gear top 14 the snail 10 Causes plastic between the worm gear top 14 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped.

• (7) If cose ≤ cos (λ ₀ '+ c ₁ ) ≤ cosd and 0 ≤ sin (λ ₀ ' + c ₁ ) in a projection of the trailing end 14r the worm-gear top of the snail 10 that the yz plane for which x = j holds, and the yz plane for which x = j + h holds, passes to the yz plane for which x = j holds, then η takes the in 3 displayed value. 31 Fig. 12 is an illustration for explaining that g '(λ ₀ ') projected on the yz plane for which x = j holds is a case of (7) for which cose ≤ cos (λ ₀ '+ c ₁ ) ≤ cosd and 0 ≤ sin (λ ₀ '+ c ₁ ).
• (8) If cose ≤ cos (λ ₄ + c ₁ ) ≤ cosd and 0 ≤ sin (λ ₄ + c ₁ ) in a projection of the trailing end 14r the worm-gear top of the snail 10 that the yz plane for which x = j holds, and the yz plane for which x = j + h holds, passes to the yz plane for which x = j holds, then η takes the in 33 displayed value. 33 Fig. 12 is a diagram for explaining an instance where g '(λ ₀ ) is projected onto the yz plane for which x = j, which satisfies condition (8) where cose ≤ cos (λ ₄ + c ₁ ) ≤ cosd and 0 ≤ sin (λ ₄ + c ₁ ).
• (9) If cose ≤ cos (λ ₀ '+ c ₁ ) ≤ cos (λ ₄ + c ₁ ) ≤ cosd, 0 ≤ sin (λ ₀ ' + c ₁ ), 0 ≤ sin (λ ₄ + c ₁ ) in a projection of the rear end 14r the worm-gear top of the snail 10 that the yz plane for which x = j holds, and the yz plane for which x = j + h holds, passes to the yz plane for which x = j holds, η takes the in 35 displayed value. 35 Fig. 12 is a diagram for explaining a case for which g '(λ ₀ ) and g' (λ ₄ ) are projected onto the yz plane for which x = j, which satisfies condition (9) for which cose ≤ cos (λ ₀ '+ c ₁ ) ≤ cos (λ ₄ + c ₁ ) ≤ cosd, 0 ≤ sin (λ ₀ + c ₁ ) and 0 ≤ sin (λ ₄ + c ₁ ).
• (10) If cos (λ ₀ '+ c ₁ ) ≤ cose and cosd ≤ cos (λ ₄ + c ₁ ) in a projection of the rear end 14r the worm-gear top of the snail 10 that the yz plane for which x = j holds, and the yz plane for which x = j + h holds, passes to the yz plane for which x = j holds, η takes the in 37 specified value. 37 13 is a diagram for explaining a case where g '(λ ₀ ') and g '(λ ₄ ) are projected onto the yz plane for which x = j, which satisfies condition (10) where cos (λ ₀ ' + c ₁ ) ≤ cose and cosd ≤ cos (λ ₄ + c ₁ ).
• (11) If cose ≤ cos (λ ₀ '+ c ₁ ) ≤ cosd, sin (λ ₀ ' + c ₁ ) ≤ 0 and cosd ≤ cos (λ ₄ + c ₁ ) in a projection of the trailing end 14r the worm-gear top of the snail 10 that the yz plane, to which applies, and the yz plane, for which x = j + h holds, passes to the yz plane for which x = j holds, η takes the in 39 displayed value. 39 13 is a diagram for explaining a case for which g '(λ ₀ ') and g '(λ ₄ ) are projected onto the plane for which x = j, which satisfies condition (11) for which cose ≤ cos (λ ₀ '+ c ₁ ) ≤ cosd, sin (λ ₀ ' + c ₁ ) ≤ 0, and cosd ≤ cos (λ ₄ + c ₁ ).
• (12) If cose ≤ cos (λ ₄ + c ₁ ) ≤ cosd, sin (λ ₄ + c ₁ ) ≤ 0, cos (λ ₀ '+ c ₁ ) ≤ cose in a projection of the trailing end 14r the worm-gear top of the snail 10 the yz plane, for which x = j holds, and the yz plane, for which x = j + h holds, on the yz plane, for which x = j holds, η takes the in 41 displayed value. 41 Fig. 12 is a diagram for explaining a case where g '(λ ₀ ') and g '(λ ₄ ) are projected onto the yz plane for which x = j, which satisfies condition (12) for which cose ≤ cos ( λ ₄ + c ₁ ) ≤ cosd, sin (λ ₄ + c ₁ ) ≤ 0 and cos (λ ₀ '+ c ₁ ) ≤ cose is satisfied.

In the case (8) and when one of the conditions (7) to (12) is satisfied in the case (9), there is a possibility that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm gear top and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 when moving back the snail 10 is trapped during the post-pressure holding step. In this case, a speed control is performed in a time interval x = x ₄ to x _{0 of} the post-pressure holding step. Herein, the examples described below illustrate speed controls (c) and (d) of the screw during the post-pressure holding step for such a case. The equations for the helical shape for each specification number of the screw 10 in the injection molding machine are stored as a data set in a database, such that when replacing the screw 10 against one with another shape, the specification number of the exchange screw 10 can be read from the database.

(c) Speed control of the worm shaft 10 in the post-pressure holding step (constant speed).

The speed control of the worm shaft 10 is performed at a preset speed V _c after the worm shaft 10 the position x ₄ (position of the furthest advance of the worm shaft 10 during the hold pressure step) until the end of the preset hold pressure step.

(d) Speed control of the worm shaft 10 during the post-pressure holding step (average speed calculation).

This applies to cases in which the holding pressure is preset over several stages. For each injection, the positions x ₄ and x _{0 are} for the worm shaft 10 stored together with the times t ₄ and t ₀ , at which this position x ₄ and x _{0 are} reached, in the event that the pressure control is carried out such that the rear end 14r the worm-gear top of the snail 10 the yz plane, for which x = j, and the yz plane, for which x = j + h holds, when the screw is moved back 10 during the pressure holding step, and the average values X ₄ , X ₀ , T ₄ and T ₀ are calculated at these positions x ₄ and x _{0 of} the screw and at the times t ₄ and t ₀ at which these positions are reached , The times t _d1 , t _d2 , t _d3 ,..., T _{dn of} the switching of the _{holding pressure} at each stage for each injection molding operation and the positions x _d1 , x _d2 , x _d3 ,... X _{dn of} the screw 10 at these times are stored and the averages thereof calculated from T _d1 , T _d2 , T _d3 ..., T _dn and X _d1 , X _d2 , X _d3 , ..., X _dn .

From positions x ₃ to x _{4 of} the screw 10 A speed control of this worm is performed at a speed V _d given by the following equation (25). In a case where the holding pressure includes a single step or speed, the calculation is simplified. Then the speed control of the screw 10 at a speed V _d , which results from the following equation (26), which connects a start position for the post-holding and an end position for the post-holding hold. Also, arbitrary measuring points may be preset in the interval x = x ₄ to x ₀ instead of a switching position for the post-pressure holding set individually for each stage, so that the speed can be calculated by recording the times at which these measuring points are passed , As long as the result of an injection process has not yet been achieved, for which the pressure control is carried out such that the rear end 14r the worm-gear top of the snail 10 the yz plane for which x = j holds and the yz plane for which x = j + h does not pass in the pressure holding step, becomes one from the start of continuous injection molding Speed control (constant speed) of the worm 10 in the above-proposed post-holding step (c).

4th embodiment

As in the third embodiment described above, the position becomes the top of the flight 12 the snail 10 at a rotational angle and an axial position in the front and rear direction thereof opposite to the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 by rendering in the form of equations of the shape of the helix 12 the snail 10 and the shape of the opening trailing edge of the rectangular feed opening 26 for injection molding differed.

(10) When 2π ≦ η

The injection molding, in which the snail 10 is returned by a path from a pitch (pitch of the flights) or more in the post-pressure holding step, requires less precision than in the above-described third embodiment. Consequently, it is not necessary to use the function of preventing pinching of plastic material according to the present invention in the injection molding machine for such an injection molding operation.

(11) When η satisfies the condition 2π - (e - d) ≦ η ≦ 2π

As already described above for the third embodiment, there are four conceivable cases of 29A to 29D based on the relationship of the position of g '(λ ₄ ) and g' (λ ₀ '). It has also been found that with the reference number 192 provided area - this is the portion of an overlap between the area (η) of λ 'and the feed opening 26 for injection molding material of the cylinder 20 - assumes a minimum value when g '(λ ₄ ) and g' (λ ₀ ') are in the in 29 Position shown to each other and thus the rotation (angle) control of the screw 10 not executed. In case of 29B to 29D For example, the control may be performed in such a manner that the reference numeral 192 provided area, which is a section in which the area (η) of λ 'and the feed opening 26 for injection molding material of the cylinder 20 overlap each other, take a minimum value by causing the worm to move 10 up to that in the 29E or 29F has shown rotated state. In the positional relationships of g '(λ ₄ ) and g' (λ ₀ ') shown in 29 , the conditions are cose ≤ cos (λ ₄ + c ₁ ) ≤ cos (λ ₀ '+ c ₁ ) ≤ cosd, 0 ≤ sin (λ ₀ ' + c ₁ ), and 0 ≦ sin (λ ₄ + c ₁ ), and hence the rotation (angle) control of the worm 10 executed if the previously described is not met. Regarding the direction in which the snail 10 is rotated about its central axis, and the amount of rotation of the screw 10 the smallest possible amount of rotation is selected on the one hand the amount of rotation to which the worm 10 is rotated in the normal direction or in the opposite direction, so that cos (λ ₀ '+ c ₁ ) = cosd and sin (λ ₀ ' + c ₁ ) = are satisfied, as shown in FIG 29E , and on the other hand, the amount of rotation by which the screw is rotated in the normal direction or the opposite direction so that cos (λ ₄ + c ₁ ) = cose and sin (λ ₄ + c ₁ ) = sine are satisfied, as shown in FIG 29F , is filmed.

(12) When 0 ≦ η ≦ 2π - (e - d)

In a case corresponding to one of the cases (7) to (12) in (9) of the above-described 3rd embodiment, the control is carried out by the screw 10 is rotated while moving from position x ₁ (position where the worm 10 stopped a dosing step for molten plastic and the turning ends) to a position x ₄ (position to which the screw 10 has been advanced furthest in the pressure holding step), so that the rear end 14r the worm-gear top of the snail 10 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 did not happen at all.

Examples of such avoidance operations, hence the rear end 14r the worm-gear top of the snail 10 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 are not at all, are for the conditions described above (7) to (12), in 32 (for condition (7)), 34 (for condition (8)), 36 (for condition (9)), 38 (for condition (10)), 40 (for condition (11)) and 42 (for condition (12)). Regarding the direction in which the snail 10 is rotated about its central axis, and the amount of rotation of the screw at this time, the smallest value is selected from on the one hand, an amount for the rotation, by which the screw is caused to perform a normal rotation (rotation in the yz plane in the opposite direction) such that cos (λ ₀ '+ c ₁ ) = cosd and sin (λ ₀ ' + c ₁ ) =, and on the other hand an amount for the rotation through which the worm 10 is caused to perform a rotation in the opposite direction (rotation in the yz plane in the normal direction) so that cos (λ ₄ + c ₁ ) = cose and sin (λ ₄ + c ₁ ) = sine are satisfied.

In a case that does not satisfy any of the conditions (7) to (12) in (9), the worm gear top of the worm passes 10 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 not, and thus no rotation control is made after completion of the dosing step. The equations for the helical flight shape for each screw serial number 10 in the injection molding machine are stored in the form of records in a database, so that after an exchange of screws of different shape and shape, the specification number of the exchange screw is read from the database. With the reference number 196 (in 32 ), the reference number 198 (in 34 ), the reference number 200 (in 36 ), the reference number 202 (in 38 ), the reference number 204 (in 40 ) and the reference numeral 206 (in 42 ) are the portions of the overlap between the feed opening 26 for injection molding material of the cylinder 20 and the rotational phase range (η) of λ 'of the screw 20 designated where there is a possibility that plastic pellets between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 be trapped.

5th embodiment

Next, an explanation will be given of a method of adjusting the rotation angle of the worm 10 or to decide for a speed control of the screw 10 over the whole post-pressure holding step, the method being a combination of: the method of adjusting the angle of rotation of the screw 10 or the speed control of the screw 10 as described above for the first embodiment and the second embodiment, wherein the position of the front end 14f the top of the helix 12 the snail 10 at a rotational angle and the position in the advancing direction and the backward moving direction with respect to the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 be distinguished from each other by reproducing, in the form of equations, the shape of the helix 12 the snail 10 and the shape of the opening leading edge of the rectangular task opening 26 for injection molding material, and the method for adjusting the angle of rotation of the screw 10 or for the speed control of the screw 10 as described above for the third embodiment and the fourth embodiment, wherein the position of the rear end 14r the top of the helix 12 the snail 10 at a rotation angle and the position in the front and rear direction of movement thereof opposite to the opening trailing edge of the feed opening 26 for the injection molding material of the cylinder 20 can be distinguished from each other by reproducing in the form of equations of the shape of the flight 12 the snail 10 as well as the shape of the rectangular task opening 26 for injection molding material.

If as a result of the determination, how the front end 14f the worm-gear top of the snail 10 at an angle of rotation and a position in the forward and backward direction thereof opposite to the opening leading edge of the feed opening 26 for injection molding material of the cylinder 20 is positioned according to the method described with reference to the first embodiment and the second embodiment, that an adjustment of the rotational angle of the screw 10 is required, then the adjustment angle is preset to the value α.

If as a result of the determination, how the rear end 14r the worm-gear top of the snail 10 at a rotational angle and a position in the forward and backward direction thereof opposite to the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is positioned according to the method described with reference to the third embodiment and the fourth embodiment, it is necessary that the rotation angle of the screw 10 to adjust, then the setting angle is preset to the value β. Here are four cases listed below at the time x = x ₁ for which the dosing process is completed.

<1>

In the post-pressure holding step, there is no possibility that the front end 14f The worm gear top causes plastic between the front end 14f and the worm gear top and the task opening 26 for injection molding material of the cylinder 20 is trapped during advancement of the screw. Also, there is no way that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw.

<2>

In the post-pressure holding step, there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is trapped during advancement of the screw, but there is no possibility that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw.

<3>

In the post-pressure holding step, there is no possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge the task opening 26 for injection molding material of the cylinder 20 is trapped during advancement of the screw, but there is a possibility that the rear end 14r the worm-gear top of the snail 10 Causes plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw.

<4>

In the post-pressure holding step, there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is trapped during advancement of the screw. Furthermore, here is the possibility that the rear end 14r the worm-gear top of the snail 10 that causes plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw.

The above cases <1>, <2>, <3>, <4> are treated as described below. Depending on the specifics of injection molding, the emphasis is placed on preventing the front end 14f the top of the helix 12 the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 during the advancement of the screw happens, or put on it, that prevents the rear end 14r of the worm gear 12 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 during the backward movement of the screw happens. In the present embodiment, an example in which the emphasis is placed on preventing the rear end from being explained is explained 14r the top of the helix 12 the opening trailing edge of the task opening 26 for injection molding material of the cylinder 20 during the backward movement of the screw happens.

In the case <1> described above, there is no need to set the angle of rotation of the worm 10 or no speed control of the worm needs to be made during the whole hold pressure step.

In the case <2> described above, no adjustment of the rotation angle of the worm 10 with the aim of preventing the back end from being carried out 14r the worm-gear top of the snail 10 should be able to cause plastic between the rear end 14r the worm gear top and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw.

A speed control of the screw 10 The first embodiment is used in such a case where there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is clamped during a forward movement of the screw.

In the case <3> described above, the rotation angle of the worm becomes 10 adjusted (with the control amount β), so that the rear end 14r the worm-gear top of the snail 10 does not cause plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw. On the basis of the equation (27) using the equation (2) and the equation (6) and the equation (28), the equation (2), the equation (7) and the equation (9) of FIG In the embodiment, it is again determined whether there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is trapped during advancement of the screw in the post-pressure holding step. If it has been determined that such a possibility exists, then the speed control for the worm becomes 10 used in the first embodiment.

In the case <4> described above, the rotation angle of the worm becomes 10 adjusted (with the control amount β), so that the rear end 14r the worm-gear top of the snail 10 does not cause plastic between the rear end 14r the worm-gear top of the snail 10 and the opening trailing edge of the feed opening 26 for injection molding material of the cylinder 20 is trapped during the backward movement of the screw or leads to a blockage. On the basis of the equation (27) using the equation (2) and the equation (6) and the equation (28), the equation (2), the equation (7) and the equation (9) of FIG In the embodiment, it is again determined whether there is a possibility that the front end 14f the worm-gear top of the snail 10 Causes plastic between the front end 14f the worm-gear top of the snail 10 and the opening leading edge of the task opening 26 for injection molding material of the cylinder 20 is trapped during advancement of the screw in the post-pressure holding step. If it has been determined that such a possibility exists, then the speed control for the worm becomes 10 used in the first embodiment.

In the above-described 1 Embodiment to 5th Embodiment, the shape is the shape in the cylinder 20 provided task opening 26 for injection molding rectangular. Next, a sixth embodiment of the present invention will be explained, in which the shape of the in-cylinder 20 provided task opening 28 is circular for the injection molding material.

6th embodiment

Hereinafter, an embodiment of the present invention will be explained with reference to the accompanying drawings, in which the feed opening 28 for injection molding material of the cylinder 20 is circular.

43 is a representation illustrating a worm gear 12 the snail 10 and the opening leading edge of a circular feed opening 28 for the injection molding material of the cylinder 20 , A filler block 24 is on the rear outer surface of the cylinder 20 attached. The task opening 28 for the injection molding material, which has a circular shape, passes through the screw cylinder 20 and the filler block 24 and communicates with the interior (worm shaft bore) of the cylinder 20 in contact with the worm shaft. The snail 10 with the helix 12 is in the auger bore of the cylinder 20 provided such that the screw 20 around the central axis 16 turn and in the direction of the central axis 16 can move (forward and backward direction). An unillustrated hopper for the supply of plastic pellets is above the filler block 24 intended. The reference number 22 denotes a nozzle. Thus, the molten plastic through the nozzle 22 be injected in an injection mold, not shown, or a (spray) tool. Determining the position of the screw 20 in the forward and backward direction as well as the determination of the rotation angle or the rotational position of the screw 10 are well-known features in the art of injection molding machines and therefore their explanation is omitted.

In 43 denotes the reference numeral 206 an enlarged partial view to illustrate the location at which the worm bore of the injection cylinder 20 with the circular task opening 28 in the filler block 24 for the injection molding material and in the cylinder 20 is associated with, the reference numeral 208 a representation of the task opening 28 for the injection molding material as seen from above the circular feed opening 28 for the injection molding material. The reference number 210 in the figure, a place where there is a possibility that plastic pellets between the front end 14f the top of the helix 12 the snail 10 and the opening leading edge of the task opening 28 for the injection molding material of the cylinder 20 during the forward movement of the screw 20 is trapped during the post-pressure holding step. The reference number 212 denotes a diagram for explaining a design of the front end 14f the worm-gear top of the snail 10 , The reference number 214 in the figure, a shape designates the opening leading edge of the feed opening 28 for the injection molding material of the cylinder 20 and the reference numeral 216 denotes a type of the front end 14f the top of the helix 12 the snail 10 ,

As in 43 shown, the position of the front end 14f the worm gear top of the worm gear 12 the snail 10 at a rotational angle (angular position) and a position in the direction of the forward and backward movement relative to the opening leading edge of the task opening 28 for the injection molding material of the cylinder 20 distinguished by rendering in the form of equations for the shape of the flight 12 the snail 10 as well as the shape (circular shape) of the opening leading edge of the feed opening 28 for the injection molding material of the cylinder 20 ,

44 Fig. 12 is a diagram for explaining the manner in which the location of the front end 14f the top of the helical flight of the snail 10 and the opening leading edge of the circular feed opening 28 for the injection molding material of the cylinder 20 in the form of equations.

The xyz coordinates will be as in 44 shown, set up first. The y axis and the z axis are set in such a way that the central axis 16 the worm shaft 10 lies on the x-axis. Here, R is the distance from the x-axis to the top 14 of the worm gear 12 the worm shaft 10 , The coordinate origin of the xyz coordinates is determined in such a way that the starting point of the helical line (worm gear) at the front end 14f the worm-gear top gangway top of the snail 10 x = 0, y = R, z = 0 for the state in which the worm lies 10 is in a furthest advanced position. For this case, the equation for the helix line of the front end 14f the worm-gear top of the snail 10 in the form of the following equation (29). The rotational phase θ of the screw 10 is set to (0 ≦ θ ≦ 2nπ), where n is a natural number.

In addition, here a distance X for moving back from the furthest advanced position of the screw 10 and a rotation angle c is added. As previously described, the most advanced position of the screw is used as the origin of the coordinates, so that the worm 10 can only move back and thus X <0. The normal direction of rotation of the screw 10 is viewed from the injection molding opening in the clockwise direction and runs in the opposite direction in the yz plane, which is why c <0. The equation for the helical spiral line of the front end 14f the worm-gear top of the snail 10 in the position X of the complete return movement or at the return end and the rotation angle c is given by the following equation (30).

The opening leading edge of the task opening 28 for injection molding material of the cylinder 20 is represented in the form of a mathematical equation as follows. The origin is given identically with the origin O in the xyz coordinates, at which the shape of the helix 12 the snail 10 is represented in the form of an equation. The opening leading edge of the task opening 28 for injection molding material of the cylinder 20 can be described by the following equation (31), by the center of the circular feed opening 28 for injection molding material as x = p and y = 0 and the radius can be taken as q. (x - p) ² + y ² = q ² (p ≦ x ≦ p + q, 0 ≦ z) (31)

The position of the front end 14f the worm-gear top of the snail 10 at the opening leading edge of the task opening 28 for injection molding material of the cylinder 20 can be determined by calculating θ which is the equation (30) and the equation (31) for a mean value X ₃ at the position x ₃ at which the worm 10 switches from speed control to pressure control in the injection molding step, and the mean value X ₄ at the position x _{4 of} the furthest advance of the worm 10 fulfilled at the end of the Nachdruckhalteschritts. The control method for the screw 10 after the determination is identical to that for the first embodiment and the second embodiment, therefore, a detailed explanation is omitted.

7th embodiment

Another embodiment of the present invention wherein the feed opening 28 for injection molding material of the cylinder 20 is circular, will now be explained with reference to the accompanying drawings.

45 is a representation for explaining the worm gear 12 the snail 10 and the opening trailing edge of the circular feed opening 28 for injection molding of the injection molding cylinder 20 , In 45 denotes the reference numeral 218 a partially enlarged image to illustrate the point at which the screw bore of the cylinder 20 with the circular task opening 28 for injection molding material contained in the filler block 24 and the cylinder 20 are provided in connection. The reference number 220 denotes an image of the circular task opening 28 for injection molding viewed from above the feed opening 28 for injection molding material. The reference number 222 in this figure denotes a location where there is a possibility that plastic between the opening trailing edge of the feed opening 28 for injection molding material of the cylinder 20 and the back end 14r the top or top surface of the flight 12 the snail 10 during the backward movement of the snail 10 is trapped during the post-pressure holding step. The reference number 224 indicates a representation to illustrate a shape of a trailing end 14r the worm-gear top of the snail 10 ; the reference number 226 in the figure denotes a shape of the opening trailing edge of the feed opening 28 for injection molding material of the cylinder 20 and the reference numeral 228 stands for a shape of the rear end 14r the worm-gear top of the snail 10 ,

As it is in 45 is shown, the position of the rear end 14r the worm gear top of the worm gear 12 the snail 10 at a rotational angle and a position in the direction forward and backward with respect to the opening trailing edge of the feed opening 28 for injection molding material of the cylinder 20 by playing - in the form of equations - the shape of the helix 12 the snail 10 as well as the shape (circular shape) of the opening trailing edge of the feed opening 28 for injection molding material of the cylinder 20 determined. Determining the position of the screw 10 in the direction of forward and backward as well as the determination of the angle of rotation of the screw 10 are well known processes in the art here, and hence their detailed description is omitted.

46 is a representation to illustrate the way in which the location of the rear end 14r the rice-shaped task opening 28 for injection molding material of the cylinder 20 in the form of equations.

First, as in 45 shown is the xyz coordinates set up. The y-axis and the z-axis are set in such a way that the central axis 16 the snail 10 coincides with the x-axis. Here R is the distance from the x-axis to the top 14 of the worm gear 12 the snail 10 , The origin O of the xy coordinates is set in such a manner that the starting point of the helix line at the rear end 14r the worm-gear top of the snail 10 x = 0, y = R, z = 0 is in a state in which the worm 10 located in the furthest advanced position. The width of the top 14 of the worm gear is set to L. In this case, the equation for the helical worm gear at the rear end 14r the worm gear top of the screw are described in the form of the following equation (32). Here is the rotational phase λ of the screw 10 predetermined such that 0 ≦ λ ≦ 2nπ is satisfied, with n of a natural number.

In addition, here is added a distance X for the return from the furthest advanced position of the screw 10 and a rotation angle c. As described above, the most advanced position of the screw is used as the origin, so that the screw 10 can only move back and thus X <0. The normal direction of rotation of the screw 10 is viewed from the injection molding opening in the clockwise direction and runs in the yz plane in the opposite direction of rotation, which is why c <0. The equation for the helical spiral line of the front end 14f the worm-gear top of the snail 10 in the position X of the complete return movement or at the return end and the rotation angle c is given by the following equation (33).

The opening trailing edge of the task opening 28 for injection molding material of the cylinder 20 is represented in the form of a mathematical equation as follows. The origin is given identically to the origin O of the xyz coordinates at which the shape of the helical flight 12 the snail 10 is described in the form of an equation. The opening trailing edge of the task opening 28 for injection molding material of the cylinder 20 can be represented by the following equation (34), which is the center of the circular feed opening 28 for injection molding material x = p and y = 0 takes and used as the radius q. (x - p) ² + y ² = q ² (p - q ≤ x ≤ p, 0 ≤ z) (34)

The position of the rear end 14r the worm-gear top of the snail 10 at the opening trailing edge of the feed opening 28 of the cylinder 20 for injection molding material, by calculating λ by the equation (33) and equation (34) for the position x _4, the furthest advancement of the screw 10 be determined during the Nachdruckhalteschritts and the next start position x _{0 of} a metering step. The control method of the screw 10 after the determination of λ is identical to that of the third embodiment and the fourth embodiment, and therefore a detailed explanation thereof is omitted.

Claims (6)

Injection molding machine with a cylinder ( 20 ), which is a task opening ( 26 . 28 ) for an injection molding material, a worm shaft ( 10 ) with a helical flight ( 12 ) rotatable in the cylinder ( 20 ) and is movable in it in the axial direction, an axial position detector, the axial position of the worm shaft ( 10 ) in the axial direction, and a rotational position detector which detects a rotational angular position of the worm shaft (FIG. 10 ), wherein the injection molding machine comprises: a determination device for a position of the flight ( 12 ) configured to determine a positional relationship between the flight ( 12 ) of the worm shaft ( 10 ) and the task opening ( 26 . 28 ) of the cylinder ( 20 ) for the injection molding material on the basis of the measured and stored by the axial position detector position of the screw shaft ( 10 ) in the axial direction at a plurality of times, the have previously been specified for an injection molding cycle preceding the current injection molding cycle, and a rotational angular position of the worm shaft measured by the rotational position detector during the current injection molding cycle (US Pat. 10 ) at the beginning of the injection process; a passport determination device designed to determine whether or not the flight ( 12 ) of the worm shaft ( 10 ) an opening leading edge of the feed opening ( 26 . 28 ) for the injection molding material when advancing the worm shaft ( 10 ) during a post-pressure holding step, on the basis of a result of the determination of the position of the worm gear (FIG. 12 ) obtained before the beginning of the post-holding step and after completion of a dosing step, and an adjusting device configured to perform based on a determination result of the pass detecting device, a setting to a position where the flight ( 12 ) of the worm shaft ( 10 ) the opening leading edge of the feed opening ( 26 . 28 ) for the injection molding material of the injection molding cylinder ( 20 ) when advancing the worm shaft ( 10 ) does not happen during the holding pressure step, characterized in that the rotation of the worm shaft ( 10 ) during a post-pressure holding step. Injection molding machine with a cylinder ( 20 ), which is a task opening ( 26 . 28 ) for an injection molding material, a worm shaft ( 10 ) with a helical flight ( 12 ) rotatable in the cylinder ( 20 ) and is movable in it in the axial direction, an axial position detector, the axial position of the worm shaft ( 10 ) in the axial direction, and a rotational position detector which detects a rotational angular position of the worm shaft (FIG. 10 ), wherein the injection molding machine comprises: a determination device for a position of the flight ( 12 ) configured to determine a positional relationship between the flight ( 12 ) of the worm shaft ( 10 ) and the task opening ( 26 . 28 ) of the cylinder ( 20 ) for the injection molding material on the basis of the measured and stored by the axial position detector position of the screw shaft ( 10 ) in the axial direction at a plurality of times previously given for an injection molding cycle preceding the current injection molding cycle and a rotational angular position of the worm shaft measured by the rotational position detector during the current injection molding cycle ( 10 ) at the beginning of the injection process; a passport determination device designed to determine whether or not the flight ( 12 ) of the worm shaft ( 10 ) an opening trailing edge of the feed opening ( 26 . 28 ) for the injection molding material when moving back the worm shaft ( 10 ) during a post-pressure holding step, on the basis of a result of the determination of the position of the worm gear (FIG. 12 ) obtained before the beginning of the post-holding step and after completion of a dosing step, and an adjusting device configured to perform based on a determination result of the pass detecting device, a setting to a position where the flight ( 12 ) of the worm shaft ( 10 ) the opening trailing edge of the feed opening ( 26 . 28 ) for the injection molding material of the injection molding cylinder ( 20 ) when moving back the worm shaft ( 10 ) does not happen during the holding pressure step, characterized in that the rotation of the worm shaft ( 10 ) during a post-pressure holding step. Injection molding machine with a cylinder ( 20 ), which is a task opening ( 26 . 28 ) for an injection molding material, a worm shaft ( 10 ) with a helical flight ( 12 ) rotatable in the cylinder ( 20 ) and is movable in it in the axial direction, an axial position detector, the axial position of the worm shaft ( 10 ) in the axial direction, and a rotational position detector which detects a rotational angular position of the worm shaft (FIG. 10 ), wherein the injection molding machine comprises: a determination device for a position of the flight ( 12 ) configured to determine a positional relationship between the flight ( 12 ) of the worm shaft ( 10 ) and the task opening ( 26 . 28 ) of the cylinder ( 20 ) for the injection molding material on the basis of the measured and stored by the axial position detector position of the screw shaft ( 10 ) in the axial direction at a plurality of times previously given for an injection molding cycle preceding the current injection molding cycle and a rotational angular position of the worm shaft measured by the rotational position detector during the current injection molding cycle ( 10 ) at the beginning of the injection process; a passport determination device designed to determine whether or not the flight ( 12 ) of the worm shaft ( 10 ) an opening leading edge of the feed opening ( 26 . 28 ) for the injection molding material when advancing the worm shaft ( 10 ) passes during a pressure holding step, and whether or not the screw flight ( 12 ) of the worm shaft ( 10 ) an opening trailing edge of the feed opening ( 26 . 28 ) for the injection molding material when moving back the worm shaft ( 10 ) during the holding pressure step, on the basis of a Determination result of the determining device for a position of the flight ( 12 ) obtained before the beginning of the post-pressure holding step and after completion of a metering step, and an adjusting device configured to perform setting by setting, before the start of the holding pressure step and after completion of a metering step, a setting value for a position in the direction of rotation of the screw shaft ( 10 ) on the whole post-pressure holding step, on the basis of a detection result of the passage detecting device and a rotational angle value of the screw, for performing adjustment to a position where the flight ( 12 ) of the worm shaft ( 10 ) an opening edge of the feed opening ( 26 . 28 ) did not happen for the injection molding material. Injection molding machine with a cylinder ( 20 ), which is a task opening ( 26 . 28 ) for an injection molding material, a worm shaft ( 10 ) with a helical flight ( 12 ) rotatable in the cylinder ( 20 ) and is movable in it in the axial direction, an axial position detector, the axial position of the worm shaft ( 10 ) in the axial direction, and a rotational position detector which detects a rotational angular position of the worm shaft (FIG. 10 ), wherein the injection molding machine comprises: a determination device for a position of the flight ( 12 ) configured to determine a positional relationship between the flight ( 12 ) of the worm shaft ( 10 ) and the task opening ( 26 . 28 ) of the cylinder ( 20 ) for the injection molding material on the basis of the measured and stored by the axial position detector position of the screw shaft ( 10 ) in the axial direction at a plurality of times previously given for an injection molding cycle preceding the current injection molding cycle and a rotational angular position of the worm shaft measured by the rotational position detector during the current injection molding cycle ( 10 ) at the beginning of the injection process, a passport determination device designed to determine whether or not the screw flight ( 12 ) of the worm shaft ( 10 ) an opening leading edge of the feed opening ( 26 . 28 ) for the injection molding material when advancing the worm shaft ( 10 ) during a post-pressure holding step, on the basis of a result of the determination of the position of the worm gear (FIG. 12 ) obtained before the beginning of the post-pressure holding step and after completion of a metering step, and a control switching device configured to switch the forward movement of the screw shaft (FIG. 10 ) during the post-pressure holding step from a pressure control to a speed control based on the determination result of the pass detecting device. Injection molding machine with a cylinder ( 20 ), which is a task opening ( 26 . 28 ) for an injection molding material, a worm shaft ( 10 ) with a helical flight ( 12 ) rotatable in the cylinder ( 20 ) and is movable in it in the axial direction, an axial position detector, the axial position of the worm shaft ( 10 ) in the axial direction, and a rotational position detector which detects a rotational angular position of the worm shaft (FIG. 10 ), wherein the injection molding machine comprises: a determination device for a position of the flight ( 12 ) configured to determine a positional relationship between the flight ( 12 ) of the worm shaft ( 10 ) and the task opening ( 26 . 28 ) of the cylinder ( 20 ) for the injection molding material on the basis of the measured and stored by the axial position detector position of the screw shaft ( 10 ) in the axial direction at a plurality of times previously given for an injection molding cycle preceding the current injection molding cycle and a rotational angular position of the worm shaft measured by the rotational position detector during the current injection molding cycle ( 10 ) at the beginning of the injection process; a passport determination device designed to determine whether or not the flight ( 12 ) of the worm shaft ( 10 ) an opening trailing edge of the feed opening ( 26 . 28 ) for the injection molding material when moving back the worm shaft ( 10 ) during a post-pressure holding step, on the basis of a result of the determination of the position of the worm gear (FIG. 12 ) obtained before the beginning of the post-holding step and after completion of a metering step, and a control switching device configured to switch the backward movement of the screw shaft (FIG. 10 ) during the post-pressure holding step from a pressure control to a speed control based on a determination result of the passing detecting device. An injection molding machine according to any one of claims 1-5, further comprising: means configured to read out a shape of a flight ( 12 ) from a database in which the shape of the helix ( 12 ) is contained in the form of equations, solely on the basis of an input of a number for the shape of the screw flight ( 12 ).

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