Injecting device and control method

Abstract

An injection device (10) according to an embodiment uses a first detection unit (38) that detects the linear motion torque of a linear motion motor (24) and a second detection unit (44) that detects the rotational torque of a rotational motor (26), and controls the linear motion motor (24) and the rotational motor (26) while monitoring the linear motion torque and the rotational torque, so that the bushing (14) is spline-fitted with the screw (12).

Description

Technical Field

[0001] The present invention relates to an injection device and a control method. Background Art

[0002] In Japanese Unexamined Patent Application Publication No. 2019-055488, a motor control unit that controls a linear motion motor and a rotary motion motor is disclosed. The linear motion motor is a motor that moves a bushing in the axial direction of a screw. The rotary motion motor is a motor that rotates the bushing around the axis of the screw.

[0003] The motor control unit controls the linear motion motor to advance the bushing from a state separated from the screw toward the screw. During the advancement of the bushing, when the torque of the linear motion motor becomes equal to or greater than a first torque, the motor control unit controls the rotary motion motor to rotate the bushing. Thereafter, when a predetermined condition is satisfied, the motor control unit stops the advancement of the bushing. The predetermined condition is a case where the torque of the linear motion motor is lower than a second torque smaller than the first torque before the rotation angle of the bushing reaches 360 degrees, or a case where the torque of the linear motion motor is not lower than the second torque even when the rotation angle of the bushing reaches 360 degrees or more. Summary of the Invention

[0004] In Japanese Unexamined Patent Application Publication No. 2019-055488, two cases are considered as cases where the torque of the linear motion motor becomes equal to or greater than the first torque. That is, the first is a case where the spline shaft and the spline hole are not engaged and the bushing contacts the screw. The second is a case where the bushing engaged with the spline shaft continues to advance and the spline shaft contacts the bottom surface of the spline hole.

[0005] However, in Japanese Unexamined Patent Application Publication No. 2019-055488, only the linear torque is monitored. Therefore, when the spline shaft contacts the bottom surface of the spline hole and the torque becomes equal to or greater than the first torque, even if the spline engagement is completed, the bushing is rotated 360 degrees. Therefore, the operation of rotating the bushing becomes meaningless.

[0006] Therefore, the present invention provides an injection device and a control method capable of improving the operation efficiency of spline engagement.

[0007] A first aspect of the present invention is an injection device including: a screw disposed along a front-rear direction, where the front-rear direction refers to the front direction of injecting injection resin and the rear direction opposite to the front direction; a bushing configured to be spline-engaged with the screw, and in the injection device, the screw and the bushing are spline-engaged, wherein,

[0008] The injection device includes:

[0009] a linear motor that moves the bushing forward and backward relative to the screw in the front-rear direction;

[0010] A rotating motor that rotates the bushing relative to the screw;

[0011] A first detection unit that detects the linear motion torque of the linear motion motor;

[0012] A second detection unit that detects the rotational torque of the rotating motor; and

[0013] A motor control unit that performs the following control process: while monitoring the linear motion torque and the rotational torque, controls the linear motion motor and the rotating motor so that the bushing is spline-fitted to the screw.

[0014] A second aspect of the present invention is a control method for an injection device, the injection device having:

[0015] A screw that is arranged in the front-rear direction, where the front-rear direction refers to the front direction of injecting the resin for injection and the rear direction opposite to the front direction;

[0016] A bushing that is formed to be capable of spline-fitting with the screw;

[0017] A linear motion motor that moves the bushing forward and backward relative to the screw in the front-rear direction;

[0018] A rotating motor that rotates the bushing relative to the screw;

[0019] A first detection unit that detects the linear motion torque of the linear motion motor; and

[0020] A second detection unit that detects the rotational torque of the rotating motor,

[0021] The injection device controls the linear motion motor and the rotating motor while monitoring the linear motion torque and the rotational torque so that the screw and the bushing are spline-fitted,

[0022] wherein,

[0023] The control method includes the following steps:

[0024] A rotating and advancing step of advancing the bushing relative to the screw while rotating;

[0025] A rotating stop step of stopping the rotation of the bushing when the rotational torque exceeds a rotational torque threshold; and

[0026] An advancing stop step of stopping the advancement of the bushing when the linear motion torque exceeds a linear motion torque threshold.

[0027] A third aspect of the present invention is a control method for an injection device, the injection device having:

[0028] A screw, which is arranged along the front-rear direction, where the front-rear direction refers to the front direction for injecting injection resin and the rear direction opposite to the front direction;

[0029] A bushing, which is formed to be able to engage with the screw by spline;

[0030] A linear motor, which moves the bushing forward and backward relative to the screw in the front-rear direction;

[0031] A rotary motor, which rotates the bushing relative to the screw;

[0032] A first detection unit, which detects the linear torque of the linear motor; and

[0033] A second detection unit, which detects the rotational torque of the rotary motor,

[0034] The injection device monitors the linear torque and the rotational torque while controlling the linear motor and the rotary motor so that the screw engages with the bushing by spline,

[0035] wherein,

[0036] The control method includes the following steps:

[0037] A rotation-advance step, which alternately repeats an advance action of advancing the bushing for a first specified time and a rotation action of rotating the bushing for a second specified time;

[0038] An advance step, which continues to advance the bushing when the rotational torque exceeds a rotational torque threshold during the advance action or the rotation action; and

[0039] An advance-stop step, which stops the advance of the bushing when the linear torque exceeds a linear torque threshold.

[0040] According to the embodiment of the present invention, not only the linear torque but also the rotational torque can be monitored to determine whether the spline engagement is achieved. Therefore, the situation of unnecessarily rotating the bushing can be reduced, and as a result, the working efficiency of the spline engagement can be improved. Brief Description of the Drawings

[0041] Figure 1 is a schematic diagram showing an injection device according to an embodiment.

[0042] Figure 2 is a diagram showing the screw and the bushing.

[0043] Figure 3 is a flowchart showing a first processing mode of the control process executed by the motor control unit to spline-engage the screw and the bushing.

[0044] Figure 4 It is a flowchart of a second processing method representing the control processing executed by the motor control unit to spline-fit the screw and the bushing.

[0045] Figure 5 It is a diagram showing the screw and the bushing of Modification 1.

[0046] Figure 6 It is a diagram showing the screw and the bushing of Modification 2.

[0047] Figure 7 It is a diagram showing the screw and the bushing of Modification 3.

[0048] Figure 8A It represents Figure 7 a diagram of the cross-section of the screw, Figure 8B and represents Figure 7 a diagram of the cross-section of the bushing.

[0049] Figure 9 It is a diagram showing the screw and the bushing of Modification 4. Detailed implementation mode

[0050] [Embodiment mode]

[0051] Figure 1 It is a schematic diagram showing an injection device 10 of one embodiment. The injection device 10 injects molding resin into a mold. In the present embodiment, the injection direction of the molding resin is set as the front direction, and the direction opposite to the injection direction is set as the rear direction. The injection device 10 includes: a screw 12, a bushing 14, a bushing fastening portion 16, and a drive mechanism 18.

[0052] The screw 12 is accommodated in a through-hole 20H of a cylinder 20. The screw 12 conveys the molding resin introduced into the through-hole 20H forward by rotation. A nozzle 22 is provided at the front end of the cylinder 20, and the molding resin conveyed by the screw 12 is ejected from the nozzle 22. The screw 12 has a screw portion 12A and a spline portion 12B.

[0053] The screw portion 12A is the front portion of the screw 12. A spiral protrusion 12P is formed on the outer peripheral surface of the screw portion 12A. The spline portion 12B is the rear portion of the screw 12 and is connected to the rear end of the screw portion 12A. Concavities and convexities capable of spline-fitting with the bushing 14 are formed on the outer peripheral surface of the spline portion 12B.

[0054] The bushing 14 is spline-fitted with the screw 12. The bushing 14 has a through-hole 14H penetrating in the front-rear direction. Concavities and convexities capable of spline-fitting with the spline portion 12B are formed on the inner peripheral surface of the through-hole 14H. A ring-shaped convex portion 14A protruding rearward from the rear end surface of the bushing 14 is provided on the bushing 14.

[0055] The bushing fastening portion 16 is a component that can fix the bushing 14. The bushing fastening portion 16 has a recess 16A that houses the convex portion 14A of the bushing 14. The bushing 14 with the convex portion 14A housed in the recess 16A is fixed to the bushing fastening portion 16 by bolts.

[0056] The drive mechanism 18 is a mechanism that drives at least one of the screw 12 and the bushing 14 to cause the bushing 14 to move relative to the screw 12. In the present embodiment, it is the drive mechanism 18 that drives the bushing 14. The drive mechanism 18 includes: a linear motor 24, a rotary motor 26, and a motor control unit 28.

[0057] The linear motor 24 is a motor that moves the bushing 14 forward and backward. A ball screw 30 that rotates together with the motor shaft is connected to the motor shaft of the linear motor 24. A sliding portion 32 is installed on the ball screw 30 so that the ball screw 30 moves forward and backward in the front - rear direction according to the rotation of the linear motor 24. A linear gear 34 is rotatably installed on the sliding portion 32. The linear gear 34 is fixed to the rear end of the bushing fastening portion 16. An encoder 36 that detects the rotation angle of the linear motor 24 and a first detection unit 38 that detects the linear torque of the linear motor 24 are provided in the linear motor 24.

[0058] The rotary motor 26 is a motor that rotates the bushing 14 relative to the screw 12. A rotary gear 40 that meshes with the linear gear 34 is connected to the motor shaft of the rotary motor 26. An encoder 42 that detects the rotation angle of the rotary motor 26 and a second detection unit 44 that detects the rotational torque of the rotary motor 26 are provided in the rotary motor 26.

[0059] In the drive mechanism 18, when the linear motor 24 rotates, according to the rotation of the linear motor 24, the linear gear 34 moves in the front - rear direction via the ball screw 30 and the sliding portion 32. In this case, the rotary gear 40 that meshes with the linear gear 34 and the rotary motor 26 move in the front - rear direction, and via the bushing fastening portion 16 that fixes the linear gear 34, the bushing 14 moves in the front - rear direction. On the other hand, when the rotary motor 26 rotates, the rotary gear 40 rotates according to the rotation of the rotary motor 26. In this case, the linear gear 34 that meshes with the rotary gear 40 rotates, and via the bushing fastening portion 16 that fixes the linear gear 34, the bushing 14 rotates.

[0060] The motor control unit 28 controls the linear motor 24 so that the rotation angle detected by the encoder 36 becomes a target value, thereby causing the bushing 14 to move forward and backward relative to the screw 12. In addition, the motor control unit 28 controls the rotary motor 26 so that the rotation angle detected by the encoder 42 becomes a target value, thereby causing the bushing 14 to rotate.

[0061] In addition, the motor control unit 28 performs the following control process: controlling the linear motor 24 and the rotary motor 26 so that the bushing 14 and the screw 12 are spline-fitted. In this case, the motor control unit 28 controls the linear motor 24 and the rotary motor 26 while monitoring the linear torque detected by the first detection unit 38 and the rotary torque detected by the second detection unit 44.

[0062] Figure 2 FIG. is a view showing the screw 12 and the bushing 14. On the outer peripheral surface of the spline portion 12B, a plurality of outer peripheral protrusions 50 are formed which extend in the front-rear direction at intervals in the circumferential direction of the spline portion 12B. The plurality of outer peripheral protrusions 50 are each divided by a fitting groove 52 which surrounds the spline portion 12B in the circumferential direction. The annular retainer 46 ( Figure 1 ) is fitted into the fitting groove 52.

[0063] The shapes of the plurality of outer peripheral protrusions 50 are the same. Hereinafter, the description related to the shape of the outer peripheral protrusion 50 is only for one of the plurality of outer peripheral protrusions 50. On the rear end portion of one of the two side surfaces 50F1, 50F2 of the outer peripheral protrusion 50 in the circumferential direction of the screw 12, an outer peripheral protrusion inclined surface 50S is formed. The outer peripheral protrusion inclined surface 50S is inclined such that the outer peripheral protrusion width 50W in the circumferential direction of the screw 12 becomes smaller as it goes toward the rear end.

[0064] On the inner peripheral surface of the through hole 14H of the bushing 14, a plurality of inner peripheral protrusions 60 are formed which extend in the front-rear direction at intervals in the circumferential direction of the through hole 14H. The shapes of the plurality of inner peripheral protrusions 60 are the same. Hereinafter, the description related to the shape of the inner peripheral protrusion 60 is only for one of the plurality of inner peripheral protrusions 60. On the front end portion of one of the two side surfaces 60F1, 60F2 of the inner peripheral protrusion 60 in the circumferential direction of the through hole 14H, an inner peripheral protrusion inclined surface 60S is formed. The inner peripheral protrusion inclined surface 60S is inclined such that the inner peripheral protrusion width 60W in the circumferential direction of the through hole 14H becomes smaller as it goes toward the front end.

[0065] Here, the control process performed by the motor control unit 28 to spline-fit the screw 12 and the bushing 14 will be described by dividing it into a first processing method and a second processing method.

[0066] Figure 3 FIG. is a flowchart showing the first processing method of the control process performed by the motor control unit 28 to spline-fit the screw 12 and the bushing 14. After the bushing 14 moves to a predetermined fitting start position separated rearward from the rear end surface of the screw 12, this control process starts. In addition, at the fitting start position, it is preferable that the rotation center line LN1 ( Figure 2 ) of the screw 12 coincides with the center line LN2 ( Figure 2 ) of the through hole 14H of the bushing 14, but the rotation center line LN1 and the center line LN2 may be slightly offset.

[0067] In step S1, the motor control unit 28 rotates the bushing 14 while advancing the bushing 14 toward the screw 12. When the advancement of the bushing 14 starts, the control process transfers to step S2.

[0068] In step S2, the motor control unit 28 compares the rotational torque detected by the second detection unit 44 with a specified rotational torque threshold value. Here, when the rotational torque does not exceed the rotational torque threshold value, the control process remains in step S2. On the other hand, when the rotational torque exceeds the rotational torque threshold value, the control process transfers to step S3.

[0069] In addition, the phenomenon that the rotational torque exceeds the rotational torque threshold value in step S2 occurs in the following state. That is, it is the engaged state where the screw 12 and the bushing 14 are spline-engaged, or the guiding state for guiding the spline engagement. Specifically, the guiding state is one of the following three states. One is the state where the front end of the inner peripheral protrusion 60 of the bushing 14 contacts the outer peripheral protrusion inclined surface 50S of the screw 12. Another is the state where the inner peripheral protrusion inclined surface 60S of the bushing 14 contacts the rear end of the outer peripheral protrusion 50 of the screw 12. Another is the state where the inner peripheral protrusion inclined surface 60S of the bushing 14 contacts the outer peripheral protrusion inclined surface 50S of the screw 12.

[0070] In step S3, the motor control unit 28 stops the rotation of the bushing 14. When the rotation of the bushing 14 stops, the control process transfers to step S4.

[0071] In step S4, the motor control unit 28 compares the linear movement torque detected by the first detection unit 38 during the advancement of the bushing 14 with a linear movement torque threshold value. Here, when the linear movement torque does not exceed the linear movement torque threshold value, the control process remains in step S4. On the other hand, when the linear movement torque exceeds the linear movement torque threshold value, the control process transfers to step S5.

[0072] In addition, the phenomenon that the linear movement torque exceeds the linear movement torque threshold value in step S4 occurs in the following state. That is, it is the state where the rear end face of the screw 12 after being spline-engaged with the bushing 14 contacts the bottom surface of the concave portion 16A of the bushing fastening portion 16.

[0073] In step S5, the motor control unit 28 stops the advancement of the bushing 14 when the linear movement torque exceeds the linear movement torque threshold value, thereby ending the control process.

[0074] Figure 4This is a flowchart showing the second processing method of the control process executed by the motor control unit 28 to spline-fit the screw 12 and the bushing 14. Similar to the first processing method, this control process starts after the bushing 14 moves to the fitting start position. In addition, at the fitting start position, it is preferable that the rotation center line LN1 ( Figure 2 ) of the screw 12 coincides with the center line LN2 ( Figure 2 ) of the through-hole 14H of the bushing 14, but the rotation center line LN1 and the center line LN2 may be slightly offset.

[0075] In step S11, the motor control unit 28 starts the forward movement of the bushing 14 for the first specified time. When the forward movement starts, the control process transfers to step S12.

[0076] In step S12, the motor control unit 28 compares the rotational torque detected by the second detection unit 44 during the forward movement with the rotational torque threshold. Here, when the rotational torque does not exceed the rotational torque threshold, the control process transfers to step S13. On the other hand, when the rotational torque exceeds the rotational torque threshold, the control process transfers to step S15.

[0077] In step S13, the motor control unit 28 starts the rotational movement of the bushing 14 for the second specified time at the position at the end of the forward movement. The second specified time may be the same as or different from the first specified time. When the rotational movement starts, the control process transfers to step S14.

[0078] In step S14, the motor control unit 28 compares the rotational torque detected by the second detection unit 44 during the rotational movement with the rotational torque threshold. Here, when the rotational torque does not exceed the rotational torque threshold, the control process returns to step S11. In this case, the motor control unit 28 starts the forward movement from the position (phase) at the end of the rotational movement. On the other hand, when the rotational torque exceeds the rotational torque threshold, the control process transfers to step S15. In addition, the phenomenon that the rotational torque exceeds the rotational torque threshold in step S14 occurs in the fitted state. On the other hand, the phenomenon that the rotational torque exceeds the rotational torque threshold in step S12 occurs in the guiding state.

[0079] In step S15, the motor control unit 28 continues to move the bushing 14 forward without rotation. When the forward movement of the bushing 14 starts, the control process transfers to step S16.

[0080] In step S16, the motor control unit 28 compares the linear motion torque detected by the first detection unit 38 during the forward movement of the bushing 14 with the linear motion torque threshold value. Here, when the linear motion torque does not exceed the linear motion torque threshold value, the control process remains at step S16. On the other hand, when the linear motion torque exceeds the linear motion torque threshold value, the control process transfers to step S17. In addition, the phenomenon that the linear motion torque exceeds the linear motion torque threshold value occurs in a state where the rear end of the screw 12 after spline fitting contacts the bottom surface of the concave portion 16A of the bushing fastening portion 16.

[0081] In step S17, the motor control unit 28 stops the forward movement of the bushing 14 when the linear motion torque exceeds the linear motion torque threshold value, thereby ending the control process.

[0082] In this way, the motor control unit 28 performs the following control process in both the first processing method and the second processing method: while monitoring the linear motion torque and the rotational torque, it controls the linear motion motor 24 and the rotational motor 26 so that the screw 12 and the bushing 14 are spline-fitted. Thereby, not only the linear motion torque but also the rotational torque can be monitored to determine whether spline fitting has occurred. Therefore, the situation where the bushing 14 rotates unnecessarily can be reduced, and as a result, the work efficiency of spline fitting can be improved.

[0083] In the first processing method, the motor control unit 28 causes the bushing 14 to advance while rotating relative to the screw 12, stops the rotation of the bushing 14 when the rotational torque exceeds the rotational torque threshold value, and ends the control process when the linear motion torque exceeds the linear motion torque threshold value. Thereby, the rotation of the bushing 14 after spline fitting can be suppressed.

[0084] In the second processing method, the motor control unit 28 alternately repeats the forward movement and the rotational movement, and when the rotational torque exceeds the rotational torque threshold value during the forward movement or the rotational movement, causes the bushing 14 to continue to advance. After that, the motor control unit 28 ends the control process when the linear motion torque exceeds the linear motion torque threshold value. Thereby, similar to the first processing method, the rotation of the bushing 14 after spline fitting can be suppressed.

[0085] In addition, when performing a plurality of forward movements that are alternately repeated with the rotational movement, the forward speeds of the respective forward movements can be the same or different. Also, the forward speed of the forward movement that is alternately repeated with the rotational movement and the forward movement that does not perform the rotational movement and causes the bushing 14 to continue to advance until the linear motion torque exceeds the linear motion torque threshold value can be the same or different.

[0086] However, on each outer peripheral protrusion 50 on the outer peripheral surface of the rear end side of the screw 12, an outer peripheral protrusion inclined surface 50S is formed. Further, on each inner peripheral protrusion 60 on the inner peripheral surface of the front end side of the bushing 14, an inner peripheral protrusion inclined surface 60S is formed. Thereby, in the following several states, spline fitting can be performed only by advancing without rotating the bushing 14. One is the state where the front end of the inner peripheral protrusion inclined surface 60S contacts the outer peripheral protrusion inclined surface 50S. Another is the state where the rear end of the outer peripheral protrusion inclined surface 50S contacts the inner peripheral protrusion inclined surface 60S. Another is the state where the inner peripheral protrusion inclined surface 60S of the bushing 14 contacts the outer peripheral protrusion inclined surface 50S of the screw 12. Therefore, compared with the case where the outer peripheral protrusion inclined surface 50S and the inner peripheral protrusion inclined surface 60S are not formed, the rotation of the bushing 14 before spline fitting can be reduced.

[0087] [Modification Example]

[0088] The above-described embodiment can be modified as follows.

[0089] (Modification Example 1)

[0090] Figure 5 FIG. shows the screw 12 and the bushing 14 of Modification Example 1. In Figure 5 structures identical to those described in the embodiment are denoted by the same reference numerals. In addition, in this modification example, descriptions overlapping those in the embodiment are omitted.

[0091] In this modification example, there are no flat surfaces at the rear end of the outer peripheral protrusion 50 of the screw 12 and at the front end of the inner peripheral protrusion 60 of the bushing 14. The rear end of the outer peripheral protrusion 50 and the front end of the inner peripheral protrusion 60 are formed in a pointed shape or a shape with rounded corners. Thereby, it is possible to avoid the situation where the rear end surface of the outer peripheral protrusion 50 contacts the front end surface of the inner peripheral protrusion 60 and the bushing 14 does not advance. Therefore, compared with the embodiment, the reliability of spline fitting can be further improved. In addition, the rotation of the bushing 14 before spline fitting can be reduced.

[0092] (Modification Example 2)

[0093] Figure 6 FIG. shows the screw 12 and the bushing 14 of Modification Example 2. In Figure 6 structures identical to those described in the embodiment are denoted by the same reference numerals. In addition, in this modification example, descriptions overlapping those in the embodiment are omitted.

[0094] In this modification example, the outer peripheral protrusion slopes 50S of the outer peripheral protrusions 50 are respectively formed on both circumferential side surfaces 50F1 and 50F2 of the screw 12. Further, the inner peripheral protrusion slopes 60S of the inner peripheral protrusions 60 are respectively formed on both circumferential side surfaces 60F1 and 60F2 of the through-hole 14H. Even in this modification example, in the following state, it is possible to cause the bushing 14 not to rotate and to perform spline fitting only by advancing. Specifically, it is a state in which the front end of the inner peripheral protrusion slope 60S contacts the outer peripheral protrusion slope 50S. Or, it is a state in which the rear end of the outer peripheral protrusion slope 50S contacts the inner peripheral protrusion slope 60S. Or, it is a state in which the inner peripheral protrusion slope 60S contacts the outer peripheral protrusion slope 50S. Therefore, compared with the case where the outer peripheral protrusion slope 50S and the inner peripheral protrusion slope 60S are not formed, the rotation of the bushing 14 before spline fitting can be reduced.

[0095] (Modification Example 3)

[0096] Figure 7 It is a diagram showing the screw 12 and the bushing 14 of Modification Example 3. Figure 8A It is showing Figure 7 a cross-sectional view of the screw 12. Figure 8B It is showing Figure 7 a cross-sectional view of the bushing 14. In Figure 7 , Figure 8A and Figure 8B , the same reference numerals are given to the structures that are the same as those described in the embodiment. In addition, in this modification example, the description overlapping with the embodiment is omitted.

[0097] In the outer peripheral protrusion 50 of this modification example, in addition to the outer peripheral protrusion slope 50S of Modification Example 2, a second outer peripheral protrusion slope 50SS is also formed. The second outer peripheral protrusion slope 50SS is inclined such that the outer diameter of the screw 12 decreases as it approaches the rear end of the outer peripheral protrusion 50. That is, the second outer peripheral protrusion slope 50SS is inclined such that the radius R1 of the screw 12 from the rotation center line LN1 of the screw 12 ( Figure 8A ) becomes smaller as it approaches the rear end of the outer peripheral protrusion 50.

[0098] Further, in the inner peripheral protrusion 60 of this modification example, in addition to the inner peripheral protrusion slope 60S of Modification Example 2, a second inner peripheral protrusion slope 60SS is also formed. The second inner peripheral protrusion slope 60SS is inclined such that the inner diameter of the bushing 14 increases as it approaches the front end of the inner peripheral protrusion 60. That is, the second inner peripheral protrusion slope 60SS is inclined such that the radius R2 of the through-hole 14H from the center line LN2 of the through-hole 14H ( Figure 8B ) becomes larger as it approaches the front end of the inner peripheral protrusion 60.

[0099] By forming the second outer peripheral protrusion inclined surface 50SS and the second inner peripheral protrusion inclined surface 60SS, the contact between the rear end surface of the outer peripheral protrusion 50 and the front end surface of the inner peripheral protrusion 60 is reduced. Therefore, the situation where the bushing 14 does not advance is reduced. As a result, the reliability of spline fitting is improved compared to the case where the second outer peripheral protrusion inclined surface 50SS and the second inner peripheral protrusion inclined surface 60SS are not formed.

[0100] (Modification Example 4)

[0101] Figure 9 FIG. is a view showing the screw 12 and the bushing 14 of Modification Example 4. In Figure 9 structures identical to those of the above structure are denoted by the same reference numerals. In addition, in this modification example, repeated descriptions are omitted.

[0102] In this modification example, the second outer peripheral protrusion inclined surface 50SS is formed not only on the outer peripheral protrusion 50 but also between the outer peripheral protrusions 50. In addition, the second inner peripheral protrusion inclined surface 60SS is formed not only on the inner peripheral protrusion 60 but also between the inner peripheral protrusions 60. Thereby, even if the center line LN2 of the through hole 14H of the bushing 14 is displaced in the radial direction of the screw 12 with respect to the rotation center line LN1 of the screw 12, spline fitting can be performed by advancing the bushing 14 toward the screw 12.

[0103] In addition, the second outer peripheral protrusion inclined surface 50SS may be formed over the entire shaft of the screw 12 from the side surface to the rear end surface of the screw 12 (see Figure 9 ). Similarly, the second inner peripheral protrusion inclined surface 60SS may be formed over the entire shaft of the bushing 14 from the inner peripheral surface to the front end surface (see Figure 9 ). The second outer peripheral protrusion inclined surface 50SS may be formed only between the outer peripheral protrusions 50. Similarly, the second inner peripheral protrusion inclined surface 60SS may be formed only between the inner peripheral protrusions 60.

[0104] (Modification Example 5)

[0105] The rear end of the outer peripheral protrusion 50 may be on the same plane as the rear end surface of the screw 12 or may be located on the front end side of the rear end surface of the screw 12. That is, the rear end of the outer peripheral protrusion 50 in the embodiment, Modification Example 1, Modification Example 2, or Modification Example 3 may be located on the front end side of the rear end surface of the screw 12. In addition, the rear end of the outer peripheral protrusion 50 in Modification Example 4 may also be on the same plane as the rear end surface of the screw 12.

[0106] The front end of the inner peripheral projection 60 may be on the same plane as the front end surface of the bushing 14, or may be located on the rear end side with respect to the front end surface of the bushing 14. That is, the front end of the inner peripheral projection 60 in the embodiment, modification 1, modification 2, or modification 3 may be located on the rear end side with respect to the front end surface of the bushing 14. Additionally, the front end of the inner peripheral projection 60 in modification 4 may also be on the same plane as the front end surface of the bushing 14.

[0107] (Modification 6)

[0108] Instead of forming the outer peripheral projection slope 50S and the inner peripheral projection slope 60S, a second outer peripheral projection slope 50SS and a second inner peripheral projection slope 60SS may be formed. Additionally, neither the outer peripheral projection slope 50S and the inner peripheral projection slope 60S nor the second outer peripheral projection slope 50SS and the second inner peripheral projection slope 60SS may be formed.

[0109] (Modification 7)

[0110] The above-described embodiment and modifications can be arbitrarily combined within a range where no contradiction occurs.

[0111] Summarizing the above as follows.

[0112] The first invention is an injection device (10) having: a screw (12) arranged along the front-rear direction, where the front-rear direction refers to the front direction for injecting injection resin and the rear direction opposite to the front direction; a bushing (14) formed to be spline-fittable with the screw, and in the injection device, the screw is spline-fitted with the bushing, wherein,

[0113] The injection device (10) has:

[0114] A linear motor (24) that moves the bushing forward and backward in the front-rear direction relative to the screw;

[0115] A rotary motor (26) that rotates the bushing relative to the screw;

[0116] A first detection unit (38) that detects the linear torque of the linear motor;

[0117] A second detection unit (44) that detects the rotational torque of the rotary motor; and

[0118] A motor control unit (28) that performs the following control process: while monitoring the linear torque and the rotational torque, controls the linear motor and the rotary motor so that the bushing is spline-fitted with the screw.

[0119] Thus, not only the direct acting torque but also the rotational torque can be monitored to determine whether the spline fitting is achieved. Therefore, the situation where the bushing rotates unnecessarily can be reduced, and as a result, the working efficiency of the spline fitting can be improved.

[0120] Alternatively, the motor control unit may advance the bushing while rotating it relative to the screw, and when the rotational torque exceeds a rotational torque threshold value, stop the rotation of the bushing, and end the control process when the direct acting torque exceeds a direct acting torque threshold value.

[0121] Thus, the rotation of the bushing after the spline fitting can be suppressed.

[0122] Alternatively, the motor control unit may alternately repeat a forward movement of advancing the bushing for a first predetermined time and a rotational movement of rotating the bushing for a second predetermined time. When the rotational torque exceeds the rotational torque threshold value during the forward movement or the rotational movement, the bushing is made to continue advancing, and the control process is ended when the direct acting torque exceeds the direct acting torque threshold value.

[0123] Thus, the rotation of the bushing after the spline fitting can be suppressed.

[0124] Alternatively, when the rotational torque does not exceed the rotational torque threshold value during the forward movement, the motor control unit starts the rotational movement at the position at the end of the forward movement.

[0125] Thus, the rotational movement can be quickly transferred from the forward movement.

[0126] Alternatively, when the rotational torque does not exceed the rotational torque threshold value during the rotational movement, the motor control unit starts the forward movement at the phase at the end of the rotational movement.

[0127] Thus, the forward movement can be quickly transferred from the rotational movement.

[0128] Alternatively, the screw has: a plurality of outer peripheral protrusions (50) formed on the outer peripheral surface of the rear end side of the screw and extending along the front-rear direction at intervals in the circumferential direction of the screw,

[0129] On each of the plurality of outer peripheral protrusions, an outer peripheral protrusion inclined surface (50S) is formed, which is inclined such that the width (50W) of the outer peripheral protrusion along the circumferential direction of the screw becomes smaller toward the rear end.

[0130] The bushing has: a through hole (14H) extending in the front-rear direction; and a plurality of inner peripheral protrusions (60) formed on the inner peripheral surface of the through hole and extending along the front-rear direction at intervals in the circumferential direction of the through hole.

[0131] On each of the plurality of inner peripheral protrusions, there is formed: an inner peripheral protrusion inclined surface (60S) that is inclined such that the width (60W) of the inner peripheral protrusion along the circumferential direction of the through hole decreases as it approaches the front end.

[0132] Thus, when the front end of the inner peripheral protrusion inclined surface contacts the outer peripheral protrusion inclined surface, or the rear end of the outer peripheral protrusion inclined surface contacts the inner peripheral protrusion inclined surface, or the inner peripheral protrusion inclined surface contacts the outer peripheral protrusion inclined surface, the bushing can be spline-fitted only by advancing without rotating. Therefore, compared with the case where the outer peripheral protrusion inclined surface and the inner peripheral protrusion inclined surface are not formed, the rotation of the bushing before spline fitting can be reduced.

[0133] Alternatively, on the rear end side of the screw, there may be formed: a second outer peripheral protrusion inclined surface (50SS) that is inclined such that the outer diameter of the screw decreases as it approaches the rear end,

[0134] On the front end side of the bushing, there is formed: a second inner peripheral protrusion inclined surface (60SS) that is inclined such that the inner diameter of the bushing increases as it approaches the front end.

[0135] Thus, the situation where the rear end surface of the outer peripheral protrusion contacts the front end surface of the inner peripheral protrusion and the bushing does not advance can be reduced. Therefore, compared with the case where the second outer peripheral protrusion inclined surface and the second inner peripheral protrusion inclined surface are not formed, the reliability of spline fitting can be improved.

[0136] Alternatively, the second outer peripheral protrusion inclined surface may be formed on the outer peripheral protrusion,

[0137] The second inner peripheral protrusion inclined surface is formed on the inner peripheral protrusion.

[0138] Thus, the reliability of spline fitting can be improved.

[0139] Alternatively, the second outer peripheral protrusion inclined surface may be formed between the outer peripheral protrusions,

[0140] The second inner peripheral protrusion inclined surface is formed between the inner peripheral protrusions.

[0141] Thus, the reliability of spline fitting can be improved.

[0142] A second invention is a control method for an injection device having:

[0143] a screw arranged along the front-rear direction, where the front-rear direction refers to the front direction of injecting injection resin and the rear direction opposite to the front direction;

[0144] a bushing formed to be capable of spline fitting with the screw;

[0145] A linear motor that moves the bushing forward and backward relative to the screw in the front-rear direction;

[0146] A rotary motor that rotates the bushing relative to the screw;

[0147] A first detection unit that detects the linear torque of the linear motor; and

[0148] A second detection unit that detects the rotational torque of the rotary motor,

[0149] The injection device monitors the linear torque and the rotational torque, and controls the linear motor and the rotary motor so that the screw and the bushing are spline-fitted.

[0150] The control method includes the following steps:

[0151] A rotation-advancing step of advancing the bushing relative to the screw while rotating;

[0152] A rotation-stopping step of stopping the rotation of the bushing when the rotational torque exceeds a rotational torque threshold; and

[0153] An advancement-stopping step of stopping the advancement of the bushing when the linear torque exceeds a linear torque threshold.

[0154] Thus, not only the linear torque but also the rotational torque can be monitored to determine whether spline fitting has occurred. Therefore, rotation of the bushing after spline fitting can be suppressed, and as a result, the working efficiency of spline fitting can be improved.

[0155] A third invention is a control method for an injection device having:

[0156] A screw arranged along the front-rear direction, where the front-rear direction refers to the front direction for injecting injection resin and the rear direction opposite to the front direction;

[0157] A bushing formed to be capable of spline fitting with the screw;

[0158] A linear motor that moves the bushing forward and backward relative to the screw in the front-rear direction;

[0159] A rotary motor that rotates the bushing relative to the screw;

[0160] A first detection unit that detects the linear torque of the linear motor; and

[0161] A second detection unit that detects the rotational torque of the rotary motor,

[0162] While monitoring the linear torque and the rotational torque, the injection device controls the linear motor and the rotational motor so that the screw is spline-fitted to the bushing.

[0163] The control method includes the following steps:

[0164] A rotation-advance step of alternately repeating an advance action of advancing the bushing for a first predetermined time and a rotation action of rotating the bushing for a second predetermined time;

[0165] An advance step of continuing to advance the bushing when the rotational torque exceeds a rotational torque threshold during the advance action or the rotation action; and

[0166] An advance-stop step of stopping the advance of the bushing when the linear torque exceeds a linear torque threshold.

[0167] Thereby, not only the linear torque but also the rotational torque can be monitored to determine whether spline fitting has occurred. Therefore, rotation of the bushing after spline fitting can be suppressed, and as a result, the work efficiency of spline fitting can be improved.

Claims

1. An injection device (10) having: a screw (12) disposed along a front-rear direction, which refers to the front direction for injecting injection resin and the rear direction opposite to the front direction; a bushing (14) configured to be spline-fitted with the screw, and in the injection device, the screw is spline-fitted with the bushing, characterized in that, The injection device has: A linear motor (24) that moves the bushing forward and backward relative to the screw in the front-rear direction; A rotary motor (26) that rotates the bushing relative to the screw; A first detection unit (38) that detects the linear torque of the linear motor; A second detection unit (44) that detects the rotational torque of the rotary motor; and A motor control unit (28) that performs the following control process: while monitoring the linear torque and the rotational torque, controls the linear motor and the rotary motor so that the bushing is spline-fitted with the screw.

2. The injection device according to claim 1, characterized in that, The motor control unit rotates and advances the bushing relative to the screw, stops the rotation of the bushing when the rotational torque exceeds a rotational torque threshold, and ends the control process when the linear torque exceeds a linear torque threshold.

3. The injection device according to claim 1, characterized in that, The motor control unit alternately repeats a forward movement of advancing the bushing for a first specified time and a rotational movement of rotating the bushing for a second specified time. When the rotational torque exceeds the rotational torque threshold during the forward movement or the rotational movement, the bushing continues to advance, and ends the control process when the linear torque exceeds the linear torque threshold.

4. The injection device according to claim 3, characterized in that, When the rotational torque does not exceed the rotational torque threshold during the forward movement, the motor control unit starts the rotational movement at the position at the end of the forward movement.

5. The injection device according to claim 3, characterized in that, When the rotational torque does not exceed the rotational torque threshold during the rotational movement, the motor control unit starts the forward movement at the phase at the end of the rotational movement.

6. The injection device according to any one of claims 1 to 5, characterized in that, The screw has: a plurality of outer peripheral protrusions (50) formed on the outer peripheral surface on the rear end side of the screw and extending along the front-rear direction at intervals in the circumferential direction of the screw, On each of the plurality of outer peripheral protrusions, there is formed: an outer peripheral protrusion inclined surface (50S) that is inclined such that the outer peripheral protrusion width (50W) along the circumferential direction of the screw becomes smaller toward the rear end, The bushing has: a through hole (14H) extending in the front-rear direction; and a plurality of inner peripheral protrusions (60) formed on the inner peripheral surface of the through hole and extending along the front-rear direction at intervals in the circumferential direction of the through hole, On each of the plurality of inner peripheral protrusions, there is formed an inner peripheral protrusion inclined surface (60S) that is inclined such that the width (60W) of the inner peripheral protrusion along the circumferential direction of the through hole decreases as it approaches the front end.

7. The injection device according to claim 6, characterized in that On the rear end side of the screw, there is formed a second outer peripheral protrusion inclined surface (50SS) that is inclined such that the outer diameter of the screw decreases as it approaches the rear end, On the front end side of the bushing, there is formed a second inner peripheral protrusion inclined surface (60SS) that is inclined such that the inner diameter of the bushing increases as it approaches the front end.

8. The injection device according to claim 7, characterized in that The second outer peripheral protrusion inclined surface is formed on the outer peripheral protrusion, The second inner peripheral protrusion inclined surface is formed on the inner peripheral protrusion.

9. The injection device according to claim 7 or 8, characterized in that The second outer peripheral protrusion inclined surface is formed between the outer peripheral protrusions, The second inner peripheral protrusion inclined surface is formed between the inner peripheral protrusions.

10. A control method for an injection device having: A screw disposed along the front-rear direction, where the front-rear direction refers to the front direction for injecting injection resin and the rear direction opposite to the front direction; A bushing configured to be spline-fitted with the screw; A linear motor that moves the bushing relative to the screw in the front-rear direction; A rotary motor that rotates the bushing relative to the screw; A first detection unit that detects the linear torque of the linear motor; and A second detection unit that detects the rotational torque of the rotary motor, The injection device controls the linear motor and the rotary motor while monitoring the linear torque and the rotational torque such that the screw and the bushing are spline-fitted, Characterized in that The control method includes the following steps: A rotation and advancement step of advancing the bushing relative to the screw while rotating; A rotation stop step of stopping the rotation of the bushing when the rotational torque exceeds a rotational torque threshold; And An advancement stop step of stopping the advancement of the bushing when the linear torque exceeds a linear torque threshold.

11. A control method for an injection device having: A screw disposed along the front-rear direction, where the front-rear direction refers to the front direction for injecting injection resin and the rear direction opposite to the front direction; A bushing configured to be spline-fitted with the screw; A linear motor that moves the bushing relative to the screw in the front-rear direction; A rotary motor that rotates the bushing relative to the screw; A first detection unit that detects the linear torque of the linear motor; and A second detection unit that detects the rotational torque of the rotary motor, The injection device controls the linear motor and the rotary motor while monitoring the linear torque and the rotational torque such that the screw and the bushing are spline-fitted, Characterized in that The control method includes the following steps: A rotation and advancement step of alternately and repeatedly performing an advancement action for advancing the bushing for a first predetermined time and a rotation action for rotating the bushing for a second predetermined time; An advancement step of continuing to advance the bushing when the rotational torque exceeds a rotational torque threshold during the advancement action or the rotation action; And An advancement stop step of stopping the advancement of the bushing when the linear motion torque exceeds a linear motion torque threshold.

Images