Injection device and control method

Abstract

In one embodiment of the injection device (10), a plurality of peripheral protrusions (50) of the screw (12) are respectively formed with peripheral protrusion slopes (50S), and a plurality of inner peripheral protrusions (60) of the through hole (14H) of the bushing (14) are respectively formed with inner peripheral protrusion slopes (60S). The injection device (10) advances the bushing (14) until the direct torque exceeds the direct torque threshold. If the rotational torque exceeds the rotational torque threshold before the direct torque exceeds the direct torque threshold, the control process ends when the direct torque exceeds the direct torque threshold.

Description

Technical Field

[0001] This invention relates to an injection device and a control method. Background Technology

[0002] Japanese Patent Application Publication No. 2019-055488 discloses a motor control unit for controlling a linear motion motor and a rotary motion motor. The linear motion motor is a motor that moves a bushing along the axial direction of a screw. The rotary motion motor is a motor that rotates the bushing about the axis of the screw.

[0003] The motor control unit controls the linear motion motor to move the bushing from a state separated from the screw towards the screw. During the bushing's forward movement, when the torque of the linear motion motor reaches or exceeds a first torque, the motor control unit controls the rotary motion motor to rotate the bushing. Summary of the Invention

[0004] In Japanese Patent Application Publication No. 2019-055488, when the torque of a direct-drive motor is greater than or equal to the first torque, two cases are considered. The first is the case where the splined shaft and splined bore are not engaged, but the bushing is in contact with the screw. The second is the case where the bushing, which is engaged with the splined shaft, continues to advance, and the splined shaft contacts the bottom surface of the splined bore.

[0005] However, Japanese Patent Application Publication No. 2019-055488 is based on the premise that the splined shaft and splined bore are not engaged, and the bushing is in contact with the screw. Therefore, in Japanese Patent Application Publication No. 2019-055488, if the bushing engaged with the splined shaft continues to advance and the splined shaft contacts the bottom surface of the splined bore, the operation of rotating the bushing becomes unnecessary.

[0006] Therefore, the present invention provides an injection device and control method that can improve the efficiency of spline fitting.

[0007] A first aspect of the present invention is an injection device comprising: a screw arranged in a front-rear direction, wherein the front direction for injecting injection resin is a direction opposite to the front direction, and a bushing formed to spline engage with the screw, wherein the screw splines into the bushing, wherein...

[0008] The injection device has:

[0009] A direct-drive motor that causes the bushing to move forward and backward relative to the screw in the front-back direction;

[0010] A rotary motor that causes the bushing to rotate relative to the screw;

[0011] The first detection unit detects the direct torque of the direct-drive motor;

[0012] The second detection unit detects the rotational torque of the rotary motor; and

[0013] The motor control unit performs the following control processing: while monitoring the direct torque and the rotational torque, it controls the direct-drive motor and the rotational motor such that the bushing is engaged with the spline of the screw.

[0014] The screw has a plurality of peripheral protrusions formed on the outer peripheral surface of the rear end side of the screw, and extending at intervals along the front-rear direction in the circumferential direction of the screw.

[0015] The plurality of peripheral protrusions are each formed with a peripheral protrusion slope, which is inclined such that the width of the peripheral protrusion decreases as it faces the rear end and along the circumference of the screw.

[0016] The bushing has: a through hole extending in the front-rear direction; and a plurality of inner peripheral protrusions formed on the inner peripheral surface of the through hole and extending at intervals along the front-rear direction in the circumferential direction of the through hole.

[0017] Each of the plurality of inner peripheral protrusions is formed with an inner peripheral protrusion slope, which slopes such that the width of the inner peripheral protrusion decreases as it faces the front end and along the circumference of the through hole.

[0018] The motor control unit advances the bushing until the direct torque exceeds the direct torque threshold. If the rotational torque exceeds the rotational torque threshold before the direct torque exceeds the direct torque threshold, the control process ends when the direct torque exceeds the direct torque threshold.

[0019] The second aspect of the present invention is a control method for an injection device having:

[0020] A screw, which is arranged along a front-to-back direction, wherein the front direction for injecting the resin for injection is the front direction and the rear direction opposite to the front direction;

[0021] A bushing, which is formed to engage with the spline of the screw;

[0022] A direct-drive motor that causes the bushing to move forward and backward relative to the screw in the front-back direction;

[0023] A rotary motor that causes the bushing to rotate relative to the screw;

[0024] The first detection unit detects the direct torque of the direct-drive motor; and

[0025] The second detection unit detects the rotational torque of the rotary motor.

[0026] The injection device monitors the linear torque and the rotary torque while controlling the linear motor and the rotary motor, so that the bushing engages with the splined screw.

[0027] The control method includes the following steps:

[0028] The forward step involves advancing the bushing until the direct torque exceeds a direct torque threshold; and

[0029] The forward stop step involves stopping the bushing's advance when the rotational torque exceeds a threshold torque before the direct torque exceeds the direct torque threshold torque.

[0030] The screw has a plurality of peripheral protrusions formed on the outer peripheral surface of the rear end side of the screw, and extending at intervals along the front-rear direction in the circumferential direction of the screw.

[0031] The plurality of peripheral protrusions are each formed with a peripheral protrusion slope, which is inclined such that the width of the peripheral protrusion decreases as it faces the rear end and along the circumference of the screw.

[0032] The bushing has: a through hole; and a plurality of inner peripheral protrusions formed on the inner peripheral surface of the through hole and extending at intervals along the front-rear direction in the circumferential direction of the through hole.

[0033] The plurality of inner circumferential protrusions are each formed with an inner circumferential protrusion slope, which is inclined such that the width of the inner circumferential protrusion decreases as it faces the front end and along the circumference of the through hole.

[0034] According to the present invention, at least one of the bushing and the screw can be advanced while at least one of the bushing and the screw is rotated by an outer peripheral protruding slope or an inner peripheral protruding slope, thereby guiding the spline engagement. Furthermore, the state of the spline engagement can be controlled by the rotational torque. Therefore, spline engagement can be performed without unnecessary rotation of the bushing, resulting in improved efficiency in spline engagement operations. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating an injection device according to one embodiment.

[0036] Figure 2 This is a diagram showing the screw and bushing.

[0037] Figure 3 This is a flowchart illustrating the control process executed by the motor control unit to engage the screw with the bushing spline.

[0038] Figure 4This diagram shows the situation where the rear end of the outer peripheral protrusion of the screw contacts the front end of the inner peripheral protrusion of the bushing.

[0039] Figure 5 It is Figure 4 An enlarged view of the contact area between the rear end of the outer peripheral protrusion and the front end of the inner peripheral protrusion.

[0040] Figure 6 This is a diagram showing the screw and bushing of modified Example 1.

[0041] Figure 7 This is a diagram showing the screw and bushing in variation example 2.

[0042] Figure 8 This is a diagram showing the screw and bushing in variation example 3.

[0043] Figure 9A It means Figure 8 A diagram of the screw cross-section. Figure 9B It means Figure 8 A diagram of the bushing cross-section.

[0044] Figure 10 This is a diagram showing the screw and bushing in variation example 4. Detailed Implementation

[0045] [Implementation Method]

[0046] Figure 1 This is a schematic diagram showing an injection apparatus 10 according to one embodiment. The injection apparatus 10 injects molding resin into a mold. In this embodiment, the injection direction of the molding resin is set as the forward direction, and the opposite direction is set as the rearward direction. The injection apparatus 10 includes: a screw 12, a bushing 14, a bushing fastening part 16, and a drive mechanism 18.

[0047] The screw 12 is housed in the through hole 20H of the cylinder 20. The screw 12, by rotating, conveys the molding resin fed into the through hole 20H forward. 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.

[0048] The screw portion 12A is the front part of the screw 12. A helical protrusion 12P is formed on the outer peripheral surface of the screw portion 12A. The spline portion 12B is the rear part of the screw 12 and is connected to the rear end of the screw portion 12A. The outer peripheral surface of the spline portion 12B has a groove and a protrusion that can engage with the spline of the bushing 14.

[0049] The bushing 14 is splinedly engaged with the screw 12. The bushing 14 has a through hole 14H that extends in the front-rear direction. A protrusion and concave surface are formed on the inner circumferential surface of the through hole 14H to engage with the spline portion 12B. An annular protrusion 14A is provided on the bushing 14, protruding rearward from the rear end face of the bushing 14.

[0050] The bushing fastener 16 secures the bushing 14 to the rear of the bushing 14. The bushing fastener 16 has a recess 16A that receives the protrusion 14A of the bushing 14. The bushing 14, in which the protrusion 14A is received in the recess 16A, is secured to the bushing fastener 16 by bolts.

[0051] The drive mechanism 18 is a mechanism that drives at least one of the screw 12 and the bushing 14 to move the bushing 14 relative to the screw 12. In this embodiment, the drive mechanism 18 drives the bushing 14. The drive mechanism 18 includes a direct-drive motor 24, a rotary motor 26, and a motor control unit 28.

[0052] The direct-drive motor 24 is a motor that moves the bushing 14 forward and backward in the front-to-back direction. A ball screw 30, which rotates together with the motor shaft, is connected to the motor shaft of the direct-drive motor 24. A sliding part 32 is installed on the ball screw 30 to allow the ball screw 30 to move forward and backward in the front-to-back direction according to the rotation of the direct-drive motor 24. A direct-drive gear 34 is rotatably mounted on the sliding part 32. The direct-drive gear 34 is fixed to the rear end of the bushing fastener 16. The direct-drive motor 24 is equipped with an encoder 36 for detecting the rotation angle of the direct-drive motor 24 and a first detection part 38 for detecting the direct-drive torque of the direct-drive motor 24.

[0053] The rotary motor 26 is a motor that rotates the bushing 14. The rotary gear 40, which meshes with the direct-drive gear 34, is connected to the motor shaft of the rotary motor 26. The rotary motor 26 is equipped with an encoder 42 for detecting the rotation angle of the rotary motor 26 and a second detection unit 44 for detecting the rotation torque of the rotary motor 26.

[0054] In the drive mechanism 18, when the direct-drive motor 24 rotates, the direct-drive gear 34 moves in the front-to-back direction via the ball screw 30 and the sliding part 32 according to the rotation of the direct-drive motor 24. In this case, the rotating gear 40 meshing with the direct-drive gear 34 and the rotary motor 26 move in the front-to-back direction, and the bushing 14 moves in the front-to-back direction via the bushing fastening part 16 that fixes the direct-drive gear 34. On the other hand, when the rotary motor 26 rotates, the rotating gear 40 rotates according to the rotation of the rotary motor 26. In this case, the direct-drive gear 34 meshing with the rotating gear 40 rotates, and the bushing 14 rotates via the bushing fastening part 16 that fixes the direct-drive gear 34.

[0055] The motor control unit 28 controls the direct drive motor 24 to make the rotation angle detected by the encoder 36 reach the target value, thereby causing the bushing 14 to move forward and backward. In addition, the motor control unit 28 controls the rotary motor 26 to make the rotation angle detected by the encoder 42 reach the target value, thereby causing the bushing 14 to rotate.

[0056] In addition, the motor control unit 28 performs the following control process: it controls the linear motor 24 and the rotary motor 26 so that the bushing 14 is splinedly engaged with the screw 12. 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.

[0057] Figure 2 This diagram shows the screw 12 and bushing 14. A plurality of peripheral protrusions 50 are formed on the outer peripheral surface of the spline portion 12B, extending at intervals along the front-rear direction in the circumferential direction of the spline portion 12B. Each of the peripheral protrusions 50 is divided by a fitting groove 52 that surrounds the spline portion 12B circumferentially. An annular retainer 46 ( Figure 1 It fits into the fitting groove 52.

[0058] Each of the plurality of peripheral protrusions 50 has the same shape. The following description relating to the shape of the peripheral protrusions 50 refers only to one of the plurality of peripheral protrusions 50. A peripheral protrusion slope 50S is formed at the rear end of one of the two sides 50F1, 50F2 of the peripheral protrusion 50 in the circumferential direction of the screw 12. The peripheral protrusion slope 50S is inclined such that the width 50W of the peripheral protrusion in the circumferential direction of the screw 12 decreases as it moves toward the rear end.

[0059] A plurality of inner circumferential protrusions 60 are formed on the inner circumferential surface of the through hole 14H of the bushing 14. These protrusions extend in the front-rear direction at intervals in the circumferential direction of the through hole 14H. Each of the plurality of inner circumferential protrusions 60 has the same shape. The following description relating to the shape of the inner circumferential protrusion 60 is only of one of the plurality of inner circumferential protrusions 60. An inner circumferential protrusion slope 60S is formed at the front end of one of the two side surfaces 60F1, 60F2 of the inner circumferential protrusion 60 in the circumferential direction of the through hole 14H. The inner circumferential protrusion slope 60S is inclined such that the width 60W of the inner circumferential protrusion decreases as it approaches the front end.

[0060] Figure 3 This is a flowchart illustrating the control process executed by the motor control unit 28 to spline-fit the screw 12 and bushing 14. This control process begins after the bushing 14 moves to a predetermined engagement start position, separating from the rear end face of the screw 12 in the rearward direction. Furthermore, at the engagement start position, the rotation center line LN1 of the screw 12 is preferably... Figure 2 The centerline LN2 of the through hole 14H of bushing 14 and bushing 14. Figure 2The rotation center lines LN1 and LN2 can be slightly offset, but the rotation center lines LN1 and LN2 can also be slightly offset.

[0061] In step S1, the motor control unit 28 moves the bushing 14 toward the screw 12. When the forward movement of the bushing 14 begins, the control process transitions from step S1 to step S2.

[0062] In step S2, the motor control unit 28 compares the direct torque detected by the first detection unit 38 during the forward movement of the bushing 14 with a predetermined direct torque threshold. Here, if the direct torque does not exceed the direct torque threshold, the control process proceeds to step S3.

[0063] In step S3, the motor control unit 28 compares the rotational torque detected by the second detection unit 44 during the forward movement of the bushing 14 with a predetermined rotational torque threshold. If the rotational torque does not exceed the rotational torque threshold, the control process returns to step S2. Conversely, if the rotational torque exceeds the rotational torque threshold, the control process proceeds to step S4. Furthermore, the phenomenon of the rotational torque exceeding the rotational torque threshold in step S3 occurs in the following ways: The front end of the inner circumferential protrusion 60 of the bushing 14 contacts the outer circumferential protrusion slope 50S of the screw 12. Alternatively, the inner circumferential protrusion slope 60S of the bushing 14 contacts the rear end of the outer circumferential protrusion 50 of the screw 12. Alternatively, the inner circumferential protrusion slope 60S of the bushing 14 contacts the outer circumferential protrusion slope 50S of the screw 12.

[0064] In step S4, the motor control unit 28 compares the direct torque detected by the first detection unit 38 during the forward movement of the bushing 14 with a direct torque threshold. Here, if the direct torque does not exceed the direct torque threshold, the control process remains in step S4. On the other hand, if the direct torque exceeds the direct torque threshold, the control process proceeds to step S5. Furthermore, in step S4, the phenomenon of the direct torque exceeding the direct torque threshold occurs in the following state: the rear end face of the screw 12, which is guided by the outer peripheral protruding slope 50S or the inner peripheral protruding slope 60S and engaged with the spline of the bushing 14, is in contact with the bottom surface of the recess 16A of the bushing fastening portion 16.

[0065] In step S5, the motor control unit 28 stops the advance of the bushing 14 when the direct torque exceeds the direct torque threshold. When the advance of the bushing 14 stops, the control process ends.

[0066] In this way, the motor control unit 28 advances the bushing 14 until the direct torque exceeds the direct torque threshold. If the rotational torque exceeds the rotational torque threshold before exceeding the direct torque threshold, the motor control unit 28 terminates the control process based on the direct torque exceeding the direct torque threshold. Therefore, while advancing the bushing 14, the screw 12 can be rotated via the outer peripheral protruding slope 50S or the inner peripheral protruding slope 60S, thereby guiding the spline engagement. Furthermore, the state of the spline engagement can be controlled by the rotational torque. Therefore, spline engagement can be performed without unnecessary rotation of the bushing 14, resulting in improved spline engagement efficiency.

[0067] However, before the rotational torque exceeds the rotational torque threshold, if the direct torque exceeds the direct torque threshold in step S2, the control process transfers to step S6. Furthermore, in step S2, the phenomenon of the direct torque exceeding the direct torque threshold occurs in the following manner: The rear end of the outer peripheral protrusion 50 contacts the front end of the inner peripheral protrusion 60, or the rear end of the splined screw 12 contacts the bottom surface of the recess 16A of the bushing fastener 16.

[0068] In step S6, the motor control unit 28 stops the advance of the bushing 14. When the advance of the bushing 14 stops, the control process transfers to step S7.

[0069] In step S7, the motor control unit 28 causes the bushing 14 to retract a predetermined distance from the position where the bushing 14 was stopped in step S6. When the bushing 14 has retracted the predetermined distance, the control process transfers to step S8.

[0070] In step S8, the motor control unit 28 retracts a predetermined distance from the position established in step S7, causing the bushing 14 to rotate by a predetermined angle. When the rotation of the bushing 14 begins, the control process transitions to step S9. This predetermined distance is the distance at which the spline engagement between the screw 12 and the bushing 14 does not disengage when the splines are engaged.

[0071] In step S9, the motor control unit 28 compares the rotational torque detected by the second detection unit 44 with a rotational torque threshold. The rotational torque detected by the second detection unit 44 is the rotational torque of the bushing 14 when it rotates while the bushing 14 is in a stopped forward state.

[0072] If the rotational torque does not exceed the rotational torque threshold in step S9, the control process returns to step S1. Furthermore, the fact that the rotational torque does not exceed the rotational torque threshold in step S9 means that the rear end face of the outer peripheral protrusion 50 is in contact with the front end face of the inner peripheral protrusion 60. Therefore, in step S2, it is determined that the direct torque exceeds the direct torque threshold. That is, the screw 12 and the bushing 14 are not yet splined engaged.

[0073] On the other hand, when the rotational torque exceeds the rotational torque threshold in step S9, the control process transfers to step S10. Furthermore, the rotational torque exceeding the threshold in step S9 means that the rear end face of the screw 12, after spline engagement with the bushing 14, is in contact with the bottom surface of the recess 16A of the bushing fastening portion 16. Therefore, it is determined in step S2 that the direct torque exceeds the direct torque threshold. That is, the screw 12 is spline engaged with the bushing 14.

[0074] In step S10, even if the rotation of the bushing 14 has not reached the predetermined angle, the motor control unit 28 stops the rotation of the bushing 14, thereby ending the control process. Alternatively, in step S10, the motor control unit 28 may also end the control process after advancing the predetermined distance retracted in step S7.

[0075] In this way, when the rotational torque does not exceed the rotational torque threshold but the direct torque exceeds the direct torque threshold, the motor control unit 28 retracts the bushing 14 a predetermined distance and then rotates it by a predetermined angle. In this case, if the rotational torque exceeds the rotational torque threshold, the motor control unit 28 terminates the control process. Thus, it is possible to accurately capture the spline engagement state and terminate the control process.

[0076] Alternatively, the motor control unit 28 can move the bushing 14 backward a predetermined distance and rotate it by a predetermined angle simultaneously, instead of moving the bushing 14 backward a predetermined distance and rotating it by a predetermined angle. When applying the process of moving the bushing 14 backward a predetermined distance and rotating it by a predetermined angle simultaneously, steps S7 and S8 are combined into one step.

[0077] On the other hand, when the rotational torque does not exceed the rotational torque threshold after rotating by a predetermined angle, the motor control unit 28 advances the bushing 14 until the direct torque exceeds the direct torque threshold. This allows for accurate detection of situations where the splines are not yet engaged, thus enabling continued control processing.

[0078] In this embodiment, a predetermined angle for rotating the bushing 14 is determined in step S8 so that the screw 12 and the bushing 14 are splinedly engaged by one rotation of the bushing 14. Figure 4 This diagram shows the situation where the rear end of the outer peripheral protrusion 50 of the screw 12 contacts the front end of the inner peripheral protrusion 60 of the bushing 14. Figure 5 It is Figure 4 An enlarged view of the contact portion between the rear end of the outer peripheral protrusion 50 and the front end of the inner peripheral protrusion 60.

[0079] The specified angle is determined to satisfy the following relationship (1). (1) a1 is the distance of the outer peripheral protrusion inclined surface 50S along the circumference of the screw 12. (1) b1 is the distance of the rear end face of the outer peripheral protrusion 50 along the circumference of the screw 12. (1) b2 is the distance of the front end face of the inner peripheral protrusion 60 along the circumference of the through hole 14H. (1) c1 is the interval between the outer peripheral protrusions 50 along the circumference of the screw 12. (1) c2 is the interval between the inner peripheral protrusions 60 along the circumference of the through hole 14H. (1) X is the distance from the center line LN2 of the through hole 14H. Figure 2 The diameter (radius) r from the tip of the inner circumferential protrusion at 60°. Figure 2 The value is obtained by multiplying by a specified angle. Furthermore, a1 and b1 have the relationship a1 + b1 = 50W. Additionally, a2 and b2 have the relationship a2 + b2 = 60W. a2 is the distance along the inner circumferential protruding inclined surface 60S of the through hole 14H.

[0080] b1+b2 <X<a1+c1-b2...(1)

[0081] By using the relationship of formula (1), the screw 12 and the bushing 14 can be splinedly engaged by one rotation of the bushing 14 relative to the screw 12.

[0082] [Variation Example]

[0083] The above-described implementation methods can also be modified as follows.

[0084] (Variation Example 1)

[0085] Figure 6 This is a diagram showing the screw 12 and bushing 14 in modified example 1. Figure 6 In this variation, structures identical to those described in the embodiments are labeled with the same symbols. Furthermore, in this variation, descriptions that are repeated in the embodiments are omitted.

[0086] In this modified example, the rear end of the outer peripheral protrusion 50 of the screw 12 is formed into a pointed shape or a rounded shape. That is, there is no flat surface at the rear end of the outer peripheral protrusion 50 of the screw 12. In other words, at the very rearmost end of the screw 12, there is no point of contact with the rotation center line LN1 of the screw 12. Figure 2 The inner peripheral protrusion 60 of the bushing 14 is orthogonal to the plane. Furthermore, the front end of the inner peripheral protrusion 60 of the bushing 14 is formed into a pointed shape or a rounded shape. That is, there is no flat surface at the front end of the inner peripheral protrusion 60 of the bushing 14. In other words, at the very front end of the bushing 14, there is no plane perpendicular to the center line LN2 of the through hole 14H of the bushing 14. Figure 2 Orthogonal planes. Furthermore, in this modified example, b1 and b2 in equation (1) above are zero.

[0087] This avoids the situation where the rear end face of the outer peripheral protrusion 50 contacts the front end face of the inner peripheral protrusion 60, preventing the bushing 14 from advancing. Therefore, compared to the previous embodiment, the reliability of the spline engagement can be further improved.

[0088] (Variation Example 2)

[0089] Figure 7 This is a diagram showing the screw 12 and bushing 14 in modified example 2. Figure 7 In this variation, structures identical to those described in the embodiments are labeled with the same symbols. Furthermore, in this variation, descriptions that are repeated in the embodiments are omitted.

[0090] In this modified example, the outer peripheral protrusion 50S of the outer peripheral protrusion 50 is formed on the two circumferential sides 50F1 and 50F2 of the screw 12. In addition, in this modified example, the inner peripheral protrusion 60S of the inner peripheral protrusion 60 is formed on the two circumferential sides 60F1 and 60F2 of the through hole 14H.

[0091] Furthermore, in this modified example, a1 in the above formula (1) is the sum of the distances along the circumference of the inclined surfaces 50S of the outer peripheral protrusions formed on the two sides 50F1 and 50F2 of the outer peripheral protrusion 50, respectively.

[0092] In this modified example, similar to the embodiment, the screw 12 and the bushing 14 can be splinedly engaged by one rotation of the bushing 14 relative to the screw 12.

[0093] (Variation Example 3)

[0094] Figure 8 This is a diagram showing the screw 12 and bushing 14 in modified example 3. Figure 9A It means Figure 8 A cross-sectional view of screw 12. Figure 9B It means Figure 8 A cross-sectional view of bushing 14. Figure 8 , Figure 9A as well as Figure 9B In this variation, structures identical to those described in the embodiments are labeled with the same symbols. Furthermore, in this variation, descriptions that are repeated in the embodiments are omitted.

[0095] In this modified example, the outer peripheral protrusion 50, in addition to the outer peripheral protrusion slope 50S of modified example 2, also forms a second outer peripheral protrusion slope 50SS. The second outer peripheral protrusion slope 50SS slopes in such a manner that the outer diameter of the screw 12 decreases towards the rear end of the outer peripheral protrusion 50. That is, the second outer peripheral protrusion slope 50SS slopes with a radius R1 ( ) of the screw 12 relative to the rotation center line LN1 of the screw 12 as it approaches the rear end of the outer peripheral protrusion 50. Figure 9AThe way it tilts becomes smaller.

[0096] Furthermore, in the inner peripheral protrusion 60 of this modified example, in addition to the inner peripheral protrusion slope 60S of modified 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 (located at the center line LN2 of the through hole 14H) increases as it approaches the front end of the inner peripheral protrusion 60. Figure 9B The tilt increases in a certain way.

[0097] This reduces the likelihood of the bushing 14 being unable to advance due to contact between the rear end face of the outer peripheral protrusion 50 and the front end face of the inner peripheral protrusion 60. Therefore, compared to the case where the second outer peripheral protrusion bevel 50SS and the second inner peripheral protrusion bevel 60SS are not formed, the reliability of the spline engagement can be further improved.

[0098] (Variation Example 4)

[0099] Figure 10 This is a diagram showing the screw 12 and bushing 14 in modified example 4. Figure 10 In this variation, structures identical to those described in the embodiments are labeled with the same symbols. Furthermore, in this variation, descriptions that are repeated in the embodiments are omitted.

[0100] In this modified example, the second outer peripheral protruding inclined surface 50SS is formed not only between the outer peripheral protrusion 50 but also between the two outer peripheral protrusions 50. Furthermore, the second inner peripheral protruding inclined surface 60SS is formed not only between the inner peripheral protrusion 60 but also between the two inner peripheral protrusions 60. Therefore, even when the center line LN2 of the through hole 14H of the bushing 14 is radially offset from the rotation center line LN1 of the screw 12, spline engagement can still be achieved as the bushing 14 advances.

[0101] Alternatively, a second outer peripheral protruding inclined surface 50SS (refer to) can be formed around the entire axis of the screw 12, disposed between the side surface and the rear end face of the screw 12. Figure 10 Similarly, a second inner circumferential protrusion slope 60SS (refer to) can also be formed around the entire axis of bushing 14, disposed between the inner circumferential surface and the front end face of bushing 14. Figure 10 Additionally, the second peripheral protrusion slope 50SS may also be formed only between the peripheral protrusions 50 and 50. Similarly, although not shown, the second inner peripheral protrusion slope 60SS may also be formed only between the inner peripheral protrusions 60 and 60.

[0102] (Variation Example 5)

[0103] The rear end of the peripheral protrusion 50 can be located on the same plane as the rear end face of the screw 12, or it can be located in a position forward of the rear end face of the screw 12. That is, the rear end of the peripheral protrusion 50 in Embodiments 1 to 3 can be located in a position forward of the rear end face of the screw 12, as in Embodiment 4. In addition, the rear end of the peripheral protrusion 50 in Embodiment 4 can also be located on the same plane as the rear end face of the screw 12, as in Embodiments 1 to 3.

[0104] The front end of the inner peripheral protrusion 60 can be located on the same plane as the front end face of the bushing 14, or it can be located further back than the front end face of the bushing 14. That is, the front end of the inner peripheral protrusion 60 in Embodiments 1-3 can also be located further back than the front end face of the bushing 14, as in Embodiment 4. In addition, the front end of the inner peripheral protrusion 60 in Embodiment 4 can also be located on the same plane as the front end face of the bushing 14, as in Embodiments 1-3.

[0105] (Variation Example 6)

[0106] The above-described implementation methods and variations can be combined arbitrarily without causing contradictions.

[0107] The invention described below can be understood based on the above-described embodiments and variations.

[0108] The first invention is an injection device (10) comprising: a screw (12) arranged in a front-rear direction, the front-rear direction referring to the front direction for injecting resin and the rear direction opposite to the front direction; and a bushing (14) formed to spline engage with the screw, wherein the screw and bushing spline engage in the injection device, wherein...

[0109] The injection device has:

[0110] A direct-drive motor (24) causes the bushing to move forward and backward relative to the screw in the front-back direction;

[0111] A rotary motor (26) rotates the bushing relative to the screw;

[0112] The first detection unit (38) detects the direct torque of the direct motor;

[0113] The second detection unit (44) detects the rotational torque of the rotary motor; and

[0114] The motor control unit (28) performs the following control process: while monitoring the direct torque and rotary torque, it controls the direct motor and rotary motor to engage the bushing with the screw spline.

[0115] The screw has: a plurality of peripheral protrusions (50) formed on the peripheral surface of the rear end side of the screw, and extending at intervals along the front-rear direction in the circumferential direction of the screw.

[0116] The multiple peripheral protrusions are each formed with a peripheral protrusion slope (50S), which slopes in such a way that the width (50W) of the peripheral protrusion decreases as it faces the rear end and along the circumference of the screw.

[0117] 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 in the front-rear direction at intervals in the circumferential direction of the through hole.

[0118] Multiple inner circumferential protrusions are each formed with an inner circumferential protrusion slope (60S), which slopes in such a way that the width (60W) of the inner circumferential protrusion decreases as it faces the front end and along the circumference of the through hole.

[0119] The motor control unit advances the bushing until the direct torque exceeds the direct torque threshold. If the rotational torque exceeds the rotational torque threshold before the direct torque exceeds the direct torque threshold, the control process ends when the direct torque exceeds the direct torque threshold.

[0120] Therefore, it is possible to guide spline engagement by simultaneously advancing at least one of the bushing and screw, and rotating at least one of the bushing and screw via the outer or inner circumferential protruding inclined surface. Furthermore, the state of spline engagement can be controlled by the rotational torque. Thus, spline engagement can be performed without unnecessary rotation of the bushing, resulting in improved efficiency in spline engagement operations.

[0121] Alternatively, when the rotational torque does not exceed the rotational torque threshold, but the direct torque exceeds the direct torque threshold, the motor control unit moves the bushing back a specified distance and rotates the bushing by a specified angle. When the rotational torque exceeds the rotational torque threshold after rotating by the specified angle, the control process ends.

[0122] Therefore, it is possible to accurately capture the spline engagement state, and as a result, control processing can be terminated.

[0123] Alternatively, when the rotational torque does not exceed the rotational torque threshold after rotating by a specified angle, the motor control unit advances the bushing until the direct torque exceeds the direct torque threshold.

[0124] Therefore, it is possible to accurately capture the state where the splines are not yet engaged, and as a result, control processing can continue.

[0125] Alternatively, the circumferential distance of the screws in the inclined surface of the outer circumferential protrusion can be defined as a1, the circumferential distance of the through holes in the inclined surface of the inner circumferential protrusion as a2, the circumferential distance of the screws in the rear end face of the outer circumferential protrusion as b1, the circumferential distance of the through holes in the front end face of the inner circumferential protrusion as b2, the circumferential interval of the screws between the outer circumferential protrusions as c1, the circumferential interval of the through holes between the inner circumferential protrusions as c2, and the value obtained by multiplying the radius (r) from the center line (LN2) of the through hole to the front end of the inner circumferential protrusion by a specified angle can be defined as X.

[0126] The angle is determined to satisfy the relationship b1+b2<X<a1+c1-b2.

[0127] Thus, by rotating the bushing relative to the screw once, the screw and bushing can be splined into engagement.

[0128] Alternatively, a second outer peripheral protruding bevel (50SS) can be formed on the rear end side of the screw, which slopes in such a way that the outer diameter of the screw decreases as it moves towards the rear end.

[0129] A second inner circumferential protrusion slope (60SS) is formed on the front end side of the bushing, which slopes in such a way that the inner diameter of the bushing increases as it moves toward the front end.

[0130] This reduces the likelihood of the bushing failing to advance due to contact between the rear end face of the outer peripheral protrusion and the front end face of the inner peripheral protrusion. Therefore, compared to the case where no second outer peripheral protrusion bevel or second inner peripheral protrusion bevel is formed, the reliability of spline engagement can be further improved.

[0131] Alternatively, the second peripheral protrusion's inclined surface may be formed from the peripheral protrusion.

[0132] The second inner peripheral protrusion slope is formed from the inner peripheral protrusion.

[0133] Therefore, compared with the case where the second peripheral protrusion slope and the second inner peripheral protrusion slope are not formed on the peripheral protrusion and the inner peripheral protrusion, the reliability of spline engagement can be further improved.

[0134] Alternatively, the second peripheral protrusion slope may be formed between the peripheral protrusions.

[0135] The second inner peripheral protrusion slope is formed between the inner peripheral protrusions.

[0136] Therefore, compared with the case where no second peripheral protrusion slope and second inner peripheral protrusion slope are formed between peripheral protrusions and between inner peripheral protrusions, the reliability of spline engagement can be further improved.

[0137] The second invention is a control method for an injection device, the injection device having:

[0138] The screw is arranged along the front-to-back direction, which refers to the front direction for injecting the resin and the rear direction opposite to the front direction.

[0139] Bushing, which is formed to engage with the spline of the screw;

[0140] A direct-drive motor causes the bushing to move forward and backward relative to the screw in the front-to-back direction;

[0141] A rotary motor that rotates the bushing relative to the screw;

[0142] The first detection unit detects the direct torque of the direct-drive motor; and

[0143] The second detection unit detects the rotational torque of the rotary motor.

[0144] The injection unit monitors the linear and rotary torques while controlling the linear and rotary motors to ensure the bushing engages with the screw spline.

[0145] The control method includes the following steps:

[0146] The forward step advances the bushing until the direct torque exceeds the direct torque threshold; and

[0147] The forward stop procedure involves stopping the bushing's advance when the rotary torque exceeds the rotary torque threshold before the direct torque exceeds the direct torque threshold.

[0148] The screw has: multiple peripheral protrusions formed on the outer peripheral surface of the rear end side of the screw, and extending at intervals along the front-rear direction in the circumferential direction of the screw.

[0149] The multiple peripheral protrusions are each formed with a peripheral protrusion slope, which slopes in such a way that the width of the peripheral protrusion decreases as it faces the rear end and along the circumference of the screw.

[0150] The bushing has: a through hole; and a plurality of inner circumferential protrusions formed on the inner circumferential surface of the through hole and extending at intervals along the front-rear direction in the circumferential direction of the through hole.

[0151] Each of the multiple inner circumferential protrusions has an inner circumferential protrusion slope, which is inclined such that the width of the inner circumferential protrusion decreases as it faces the front end and along the circumference of the through hole.

[0152] Therefore, it is possible to guide spline engagement by simultaneously advancing at least one of the bushing and screw, and rotating at least one of the bushing and screw via the outer or inner circumferential protruding inclined surface. Furthermore, the state of spline engagement can be controlled by the rotational torque. Thus, spline engagement can be performed without unnecessary rotation of the bushing, resulting in improved efficiency in spline engagement operations.

[0153] Alternatively, the control method may include the following steps:

[0154] In the retraction rotation step, if the rotational torque does not exceed the rotational torque threshold, but the direct torque exceeds the direct torque threshold, the bushing is retracted a specified distance and rotated a specified angle; and

[0155] The second forward stopping step involves stopping the bushing's forward movement when the rotational torque exceeds a threshold after rotating by a specified angle.

[0156] Therefore, it is possible to accurately capture the spline engagement state, and as a result, control processing can be terminated.

[0157] Alternatively, in the control method, if the rotational torque does not exceed the rotational torque threshold after rotating by a specified angle, the system returns to the forward step.

[0158] Therefore, it is possible to accurately capture the state where the splines are not yet engaged, and as a result, control processing can continue.

Claims

1. An injection device (10) comprising: a screw (12) arranged along a front-rear direction, wherein the front direction refers to the direction in which a resin for injection is injected and the opposite rear direction; a bushing (14) formed to spline engage with the screw, wherein the screw is splinedly engaged with the bushing in the injection device, characterized in that, The injection device has: A direct-drive motor (24) causes the bushing to move forward and backward relative to the screw in the front-back direction; A rotary motor (26) rotates the bushing relative to the screw; The first detection unit (38) detects the direct torque of the direct motor; The second detection unit (44) detects the rotational torque of the rotary motor; and The motor control unit (28) performs the following control process: while monitoring the direct torque and the rotational torque, it controls the direct motor and the rotational motor such that the bushing engages with the screw spline. The screw has a plurality of peripheral protrusions (50) formed on the outer peripheral surface of the rear end side of the screw, and extending at intervals along the front-rear direction in the circumferential direction of the screw. The plurality of peripheral protrusions are each formed with a peripheral protrusion slope (50S), which is inclined such that the width (50W) of the peripheral protrusion decreases as it faces the rear end along the circumference of the screw. 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 at intervals along the front-rear direction in the circumferential direction of the through hole. Each of the plurality of said inner peripheral protrusions is formed with an inner peripheral protrusion slope (60S), which slopes such that the width (60W) of the inner peripheral protrusion decreases as it faces the front end and along the circumference of the through hole. The motor control unit advances the bushing until the direct torque exceeds the direct torque threshold. If the rotational torque exceeds the rotational torque threshold before the direct torque exceeds the direct torque threshold, the control process ends when the direct torque exceeds the direct torque threshold.

2. The injection device according to claim 1, characterized in that, When the rotational torque does not exceed the rotational torque threshold, but the direct torque exceeds the direct torque threshold, the motor control unit moves the bushing back a predetermined distance and rotates the bushing by a predetermined angle. When the rotational torque exceeds the rotational torque threshold by rotating the predetermined angle, the control process ends.

3. The injection device according to claim 2, characterized in that, When the rotational torque does not exceed the rotational torque threshold when the predetermined angle is rotated, the motor control unit advances the bushing until the direct torque exceeds the direct torque threshold.

4. The injection device according to claim 2 or 3, characterized in that, When the dimension component of the outer peripheral protrusion inclined surface in the circumferential direction of the screw is defined as a1, the dimension component of the inner peripheral protrusion inclined surface in the circumferential direction of the through hole is defined as a2, the dimension component of the rear end face of the outer peripheral protrusion in the circumferential direction of the screw is defined as b1, the dimension component of the front end face of the inner peripheral protrusion in the circumferential direction of the through hole is defined as b2, the interval between two adjacent outer peripheral protrusions in the circumferential direction of the screw is defined as c1, the interval between two adjacent inner peripheral protrusions in the circumferential direction of the through hole is defined as c2, and the value obtained by multiplying the radius (r) from the center line (LN2) of the through hole to the front end of the inner peripheral protrusion by the specified angle is defined as X, The specified angle is determined to satisfy the relationship b1+b2<X<a1+c1-b2.

5. The injection device according to any one of claims 1 to 3, characterized in that, A second peripheral protruding inclined surface (50SS) is formed on the rear end side of the screw, which is inclined such that the outer diameter of the screw decreases as it moves towards the rear end. A second inner circumferential protruding inclined surface (60SS) is formed on the front end side of the bushing, which is inclined such that the inner diameter of the bushing increases as it moves toward the front end.

6. The injection device according to claim 5, characterized in that, The second peripheral protrusion slope is formed on the peripheral protrusion. The second inner peripheral protrusion slope is formed on the inner peripheral protrusion.

7. The injection device according to claim 5, characterized in that, The second peripheral protrusion slope is formed between the peripheral protrusions. The second inner peripheral protrusion slope is formed between the inner peripheral protrusion and the inner peripheral protrusion.

8. A control method for an injection device having: A screw, which is arranged along a front-to-back direction, wherein the front direction for injecting the resin for injection is the front direction and the rear direction opposite to the front direction; A bushing, which is formed to engage with the spline of the screw; A direct-drive motor that causes the bushing to move forward and backward relative to the screw in the front-back direction; A rotary motor that causes the bushing to rotate relative to the screw; The first detection unit detects the direct torque of the direct-drive motor; and The second detection unit detects the rotational torque of the rotary motor. The injection device monitors the linear torque and the rotary torque while controlling the linear motor and the rotary motor, so that the bushing engages with the splined screw. Its features are, The control method includes the following steps: The forward step involves advancing the bushing until the direct torque exceeds a direct torque threshold; and The forward stop step involves stopping the bushing's advance when the rotational torque exceeds a threshold torque before the direct torque exceeds the direct torque threshold torque. The screw has a plurality of peripheral protrusions formed on the outer peripheral surface of the rear end side of the screw, and extending at intervals along the front-rear direction in the circumferential direction of the screw. The plurality of peripheral protrusions are each formed with a peripheral protrusion slope, which is inclined such that the width of the peripheral protrusion decreases as it faces the rear end and along the circumference of the screw. The bushing has: a through hole; and a plurality of inner peripheral protrusions formed on the inner peripheral surface of the through hole and extending at intervals along the front-rear direction in the circumferential direction of the through hole. The plurality of inner circumferential protrusions are each formed with an inner circumferential protrusion slope, which is inclined such that the width of the inner circumferential protrusion decreases as it faces the front end and along the circumference of the through hole.

9. The control method according to claim 8, characterized in that, The control method includes the following steps: In the retraction rotation step, when the rotational torque does not exceed the rotational torque threshold, but the direct torque exceeds the direct torque threshold, the bushing is retracted a predetermined distance and rotated a predetermined angle; and The second forward stopping step involves stopping the advance of the bushing when the rotational torque exceeds the rotational torque threshold due to rotation by the predetermined angle.

10. The control method according to claim 9, characterized in that, If the rotational torque does not exceed the rotational torque threshold when the specified angle is rotated, return to the forward step.

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