Phase adjustment device and phase adjustment method

Abstract

A phase adjustment device (70) for a drive device (12) having a first motor (26) and a second motor (28) configured to move a movable part (22), a first drive force transmission mechanism (32) configured to convert a rotational force of the first motor into a linear force and transmit the linear force to the movable part, and a second drive force transmission mechanism (34) configured to convert a rotational force of the second motor into a linear force and transmit the linear force to the movable part, the phase adjustment device comprising: a torque procurement unit (82) configured to procure a torque of the first motor or the second motor, a position acquisition unit (80) configured to acquire a rotational position of the first motor, a first motor control unit (84a) configured to rotate the first motor in a first direction of rotation until the torque exceeds a threshold value, and then to rotate the first motor in a second direction of rotation opposite to the first direction of rotation until the torque again exceeds the threshold value, a storage control unit (86) configured to store the rotational position of the first motor when the first motor is rotated in the first rotational direction and the torque exceeds the threshold value in a storage unit (90) as a first rotational position (Θ1) and to store the rotational position of the first motor when the first motor is rotated in the second rotational direction and the torque exceeds the threshold value again in the storage unit as a second rotational position (Θ2), and a phase position calculator (88) configured to calculate a rotational position of the first motor, at which a relative position of the movable part in a play of the second drive force transmission mechanism and a relative position of the movable part in a play of the first drive force transmission mechanism coincide with each other within a certain range, as a third rotational position (Θ3) on the basis of the first rotational position and the second rotational position, and a second motor control unit (84b) configured to rotate the first motor to the third rotational position.

Description

Background of the inventionField of the invention

[0001] The present invention relates to a phase adjusting device and a phase adjusting method for a drive device. Description of the state of the art

[0002] In the drive device of the injection device of the injection molding machine described in Japanese Patent Laid-Open No. JP 2016-002745 A, the movable part equipped with a piston is driven linearly by two drive shafts. Each of the drive shafts includes a motor and a drive transmission mechanism that converts the motor's rotational power into linear motion. These drive transmission mechanisms have backlash, which usually causes a time delay between the time each of the two motors starts rotating and the time the movable part starts moving. Due to the backlash, the two drive shafts have different initial phases, and the movable part is usually moved by only one drive shaft.If the initial phases of the two drive shafts are not aligned, problems such as mechanical distortion, additional loads on the motors, and misalignment due to tilting of the injection mechanism occur. Therefore, adjusting the origin of the drive shafts in the injection molding machine requires adjustment so that the initial phases of the two drive shafts are aligned so that they are controlled synchronously. Japanese Patent Application Laid-Open No. JP 2016-002745 describes a configuration in which phase difference adjustment pulleys are provided to adjust the initial phases of the two drive shafts in terms of backlash so that they are controlled synchronously.

[0003] From DE 600 17393 T2 a drive motor for providing power for the operation of injection moulding machines is known, in which two electric motors are controlled by separate motor drive circuits.

[0004] JP 7050529B2 discloses a motor drive for an injection molding machine that can reliably detect when a moving part is operating at an unexpected speed. For this purpose, a measuring unit is provided that measures the voltage of any phase of a three-phase motor driving a moving part. A molding unit converts a measured voltage into a pulse wave, and a monitoring unit counts the pulse wave to determine the speed of the three-phase motor and outputs a signal indicating an abnormality if the detected speed exceeds a predetermined value.

[0005] DE 10 2017 129 973 A1 describes a device for removing a molded product, wherein the device suppresses displacement vibrations of an attachment mounted on a leading end of an approach frame by means of active control using an electromagnetic actuator. One or more electromagnetic actuators are positioned on a part of the approach frame opposite the attachment. An active vibration suppression system suppresses the displacement vibration of the attachment by having the electromagnetic actuators generate a vibration in the same phase as the displacement vibration of the attachment. Summary of the invention

[0006] However, Japanese Patent Application Laid-Open No. 2016-002745 A requires the provision of an additional mechanism, such as phase difference adjustment pulleys. However, there is no description of a specific adjustment method.

[0007] It is therefore an object of the present invention to propose a phase adjusting device and a phase adjusting method which, with a simple structure, adjusts the initial phases of the two drive shafts for synchronous control.

[0008] A first aspect of the present invention is a phase adjustment device for a drive device having a first motor and a second motor configured to move a movable part, a first drive force transmission mechanism configured to convert a rotational force of the first motor into a linear force and transmit the linear force to the movable part, and a second drive force transmission mechanism configured to convert a rotational force of the second motor into a linear force and transmit the linear force to the movable part, wherein the phase adjustment device comprises: a torque acquisition unit configured to acquire a torque of the first motor or the second motor, a position acquisition unit configured to acquire a rotational position of the first motor, a first motor control unit,which is designed to rotate the first motor in a first direction of rotation until the torque exceeds a threshold value, and then to rotate the first motor in a second direction of rotation opposite to the first direction of rotation until the torque again exceeds the threshold value, a storage control unit which is designed to store the rotational position of the first motor, when the first motor is rotated in the first direction of rotation and the torque exceeds the threshold value, in a storage unit as a first rotational position and to store the rotational position of the first motor, when the first motor is rotated in the second direction of rotation and the torque again exceeds the threshold value, in the storage unit as a second rotational position, a phase position calculator which is designed toto calculate, as a third rotational position, a rotational position of the first motor at which a relative position of the movable part at a backlash of the second drive force transmission mechanism and a relative position of the movable part at a backlash of the first drive force transmission mechanism coincide with each other within a certain range, based on the first rotational position and the second rotational position, and a second motor control unit configured to rotate the first motor to the third rotational position.

[0009] A second aspect of the present invention is a phase adjustment method for a drive device having a first motor and a second motor configured to move a movable part, a first drive force transmission mechanism configured to convert a rotational force of the first motor into a linear force and transmit the linear force to the movable part, and a second drive force transmission mechanism configured to convert a rotational force of the second motor into a linear force and transmit the linear force to the movable part, the phase adjustment method comprising: a torque acquisition step for acquiring a torque of the first motor or the second motor, a position acquisition step for acquiring a rotational position of the first motor,a first motor control step for rotating the first motor in a first rotational direction until the torque exceeds a threshold value; a first storage control step for storing the rotational position of the first motor when the first motor is rotated in the first rotational direction and the torque exceeds the threshold value in a storage unit as a first rotational position; a second motor control step for rotating the first motor in a second rotational direction opposite to the first rotational direction until the torque again exceeds the threshold value; a second storage control step for storing the rotational position of the first motor when the first motor is rotated in the second rotational direction and the torque again exceeds the threshold value in the storage unit as a second rotational position; a phase position calculation step for calculating a rotational position of the first motor;wherein a relative position of the movable part at a backlash of the second drive force transmission mechanism and a relative position of the movable part at a backlash of the first drive force transmission mechanism coincide with each other within a certain range, as a third rotational position based on the first rotational position and the second rotational position, and a third motor control step for rotating the first motor to the third rotational position.

[0010] With the present invention, it is possible, with a simple structure, to adjust the initial phases of the two drive shafts so that they are controlled synchronously.

[0011] The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of example. Short description of the drawings Fig. 1 is a plan view of an injection device according to an embodiment, Fig. 2 is a diagram showing the structure of a control device in an embodiment, Fig. 3 is a schematic diagram illustrating a phase adjustment method according to an embodiment, Fig. 4 is a flowchart for explaining a phase adjustment method according to an embodiment, and Fig. 5 is a flowchart for explaining the operations of setting a first motor and a second motor to the original position. Description of the preferred embodiments

[0012] A phase adjusting device and a phase adjusting method according to the present invention will be described in more detail below in connection with a preferred embodiment and with reference to the accompanying drawings. [Embodiment]

[0013] Fig. 1 is a plan view of an injection device 10 according to an embodiment. The X-direction, the Y-direction, and the Z-direction shown in Fig. 1 are perpendicular to each other, and gravity acts in the negative Z direction. An injection molding machine includes the injection device 10 and a clamping device, but the clamping device is not shown here.

[0014] The injection device 10 comprises a drive device 12 and a control device 16 which controls the drive device 12.

[0015] The drive device 12 comprises a movable part 22 with a piston 20, a first motor 26 and a second motor 28 for moving the movable part 22, a first drive force transmission mechanism 32 and a second drive force transmission mechanism 34.

[0016] The first drive force transmission mechanism 32 includes a pulley 26p fixed to a motor shaft 26a of the first motor 26, a ball screw 36, a pulley 36p fixed to the ball screw 36, a belt 38 wound around the pulley 26p and the pulley 36p, and a nut 36n engaged with the ball screw 36. The ball screw 36 is arranged to pass through a fixing portion 40 and rotate about an axis in the Y direction as a rotational axis. However, it is fixed so that it cannot move in the Y direction relative to the fixing portion 40. The nut 36n is fixed to the movable part 22. Therefore, the driving force transmission mechanism 32 converts the rotational force of the first motor 26 into a linear force and transmits the linear force to the movable part 22.The first motor 26 and the first drive force transmission mechanism 32 form a drive shaft (first drive shaft).

[0017] The second drive force transmission mechanism 34 includes a pulley 28p fixed to a motor shaft 28a of the second motor 28, a ball screw 42, a pulley 42p fixed to the ball screw 42, a belt 44 wound around the pulley 28p and the pulley 42p, and a nut 42n engaged with the ball screw 42.

[0018] The ball screw 42 is arranged to pass through the fixing portion 40 and rotate around an axis in the Y direction as a rotation axis. However, it is fixed so that it does not move relative to the fixing portion 40 in the Y direction. The nut 42n is fixed to the movable part 22. Therefore, the second driving force transmission mechanism 34 converts the rotational force of the second motor 28 into a linear force and transmits the linear force to the movable part 22. The second motor 28 and the second driving force transmission mechanism 34 constitute a drive shaft (second drive shaft).

[0019] Note that drive shafts of the same size and shape are used as the first drive shaft and the second drive shaft. Therefore, the clearance of the first drive force transmission mechanism 32 and the clearance of the second drive force transmission mechanism 34 are substantially the same size (width).

[0020] The mounting section 40 and a mounting section 46 are connected via four rods 50 extending in the Y-direction. Fig. 1, the two rods located on the negative Z-direction side are obscured by the front rods and are therefore not visible. The four rods 50 pass through the movable part 22. The movable part 22 can move along the four rods 50 in the Y-direction and the negative Y-direction.

[0021] The movable part 22 includes a motor 56 for rotating the piston 20. A belt 58 is wound around a pulley 56p fixed to a motor shaft 56a of the motor 56 and a pulley 20p fixed to the piston 20. The piston 20 passes through the fixed portion 46 and is inserted into a cylinder 60. Thus, the piston 20 is rotationally driven by the motor 56, and the movable part 22 moves in the Y direction so that the piston 20 is inserted to the inner tip of the cylinder 20. With this configuration, the injection device 10 can inject molten plastic, resin, or the like supplied to the cylinder 60 into the chuck through the opening at the tip of the cylinder 60.

[0022] Fig. Fig. 2 is a configuration diagram of the control device 16 in the embodiment. The control device 16 includes a processor, such as a CPU (central processing unit), and a memory, and serves as the control device 16 of the present embodiment by executing a program stored in the memory. The control device 16 includes a phase adjustment device 70. Although this is not shown in Fig. 1 is not shown, the first motor 26 is connected to an encoder (rotary encoder) 74 for measuring the rotational position of the first motor 26 and to a torque sensor 76 for measuring the torque (a scale value, the absolute value of the torque) of the first motor 26.

[0023] The phase adjustment device 70 includes a position acquisition unit 80, a torque acquisition unit 82, a motor control unit 84, a memory control unit 86, a phase position calculator 88, and a storage unit 90.

[0024] The position acquisition unit 80 acquires the rotational position of the first motor 26 measured by the encoder 74. The torque acquisition unit 82 acquires the torque of the first motor 26 measured by the torque sensor 76. The torque acquisition unit 82 calculates and determines the torque based on, for example, the current flowing through the first motor 26.

[0025] The motor control unit 34 controls the first motor 26 and the second motor 28. The motor control unit 84 includes a first motor control unit 84a and a second motor control unit 84b to perform the control described below.

[0026] The memory control unit 86 stores the rotational position of the first motor 26 in the memory unit 90.

[0027] The phase position calculator 88 calculates the set phase position based on the rotational position of the first motor 26 stored in the storage unit 90. The set phase position will be described later.

[0028] Fig. 3 is a schematic diagram for explaining the phase adjustment method of the embodiment. Fig. 3-(1) shows the relationship between the initial states of the movable part 22, the first drive force transmission mechanism 32, and the second drive force transmission mechanism 34 before the start of phase adjustment. The vertical axis in Fig. 3 indicates the rotational position Θ of the motor shaft 26a of the first motor 26, and the upper direction of the vertical axis indicates a first rotational direction, while the lower direction indicates a second rotational direction opposite to the first rotational direction. As shown in Fig. 3, the positional relationship between the first drive force transmission mechanism 32 and the movable part 22 has a degree of freedom corresponding to the width of the play of the first drive force transmission mechanism 32. Similarly, the positional relationship between the second drive force transmission mechanism 34 and the movable part 22 has a degree of freedom corresponding to the width of the play of the second drive force transmission mechanism 34. Here, the play of the first drive force transmission mechanism 32 is the play between the first motor 26 and the movable part 22, and the play of the second drive force transmission mechanism 34 is the play between the second motor 28 and the movable part 22.When the two drive shafts are controlled synchronously, due to this play, it is preferable that the relative position of the movable part 22 in the play of the first drive force transmission mechanism 32 coincides with the relative position of the movable part 22 in the play of the second drive force transmission mechanism 34. Even when the first motor 26 and the second motor 28 are rotated synchronously in the first rotational direction, the relative position of the movable part 22 in the play of the first drive force transmission mechanism 32 and the relative position of the movable part 22 in the play of the second drive force transmission mechanism 34 are not aligned with each other, as shown in FIG. Fig. For example, as shown in Fig. 3-(1), the movable part 22 is substantially moved by the second drive force transmission mechanism 34. Therefore, the relative positions of the movable part 22 in the clearance of the first drive force transmission mechanism 32 and the relative position of the movable part 22 in the clearance of the second drive force transmission mechanism 34 are preferably matched within a certain range. In the present embodiment, the phase of the first motor 26 is adjusted to match the initial phases of the two drive shafts to be synchronously controlled. Fig. 4 is a flowchart for explaining the phase adjustment method according to the embodiment.

[0029] In the initial state according to Fig. 3-(1), the motor shaft 26a of the first motor 26 is arranged at a rotational position Θ0. From this state, the phase adjustment is carried out according to the flow chart in Fig. 4 started.

[0030] First, the first motor control unit 84a rotates the first motor 26 in the first rotational direction (step S1). At this time, the first motor control unit 84a can control the rotational position of the second motor 28 to be fixed. By fixing the rotational position of the second motor 28, the phase adjustment can be performed more reliably. Note that when the first motor 26 is rotated, the movable part 22 may move due to mechanical friction or the like even if the movable part 22 is disposed at an intermediate position of the clearance width of the first driving force transmission mechanism 32.

[0031] Then, the first engine control unit 84a determines whether the torque acquired by the torque acquisition unit 82 exceeds a certain threshold (step S2). If the torque is equal to or less than the threshold (step S2: NO), control returns to step S1.

[0032] In the case where the torque exceeds the threshold value (step S2: YES), the first motor control unit 84a stops the rotation of the first motor 26 (step S3). Here, the case where the torque exceeds the threshold value is Fig. 3-(2). In this state, both the backlash between the first motor 26 and the movable part 22 in the first rotational direction and the backlash between the second motor 28 and the movable part 22 in the second rotational direction are eliminated, so that the torque exceeds the threshold value. Then, the first motor control unit 84a stores the rotational position of the first motor 26 acquired by the position acquisition unit 80 in the storage unit 90 as a first rotational position Θ1 (step S4).

[0033] After step S4, the first motor control unit 84a rotates the first motor 26 in the second rotation direction opposite to the first rotation direction (step S5). At this time, the first motor control unit 84a can control the rotation position of the second motor 28 to be fixed. By fixing the rotation position of the second motor 28, the phase adjustment can be performed more reliably.

[0034] Then, the first engine control unit 84a determines whether the torque acquired by the torque acquisition unit 82 again exceeds the set threshold (step S6). If the torque is equal to or less than the threshold (step S6: NO), control returns to step S5.

[0035] In the case where the torque exceeds the threshold again (step S6: YES), the first motor control unit 84a stops the rotation of the first motor 26 (step S7). Here, the case where the torque exceeds the threshold again is Fig. 3-(3). In this state, both the backlash between the first motor 26 and the movable part 22 in the second rotational direction and the backlash between the second motor 28 and the movable part 22 in the first rotational direction are eliminated, so that the torque again exceeds the threshold value. Then, the first motor control unit 84a stores the rotational position of the first motor 26 acquired by the position acquisition unit 80 in the storage unit 90 as a second rotational position Θ2 (step S8). In steps S2 and S6, the determination is made based on the magnitude (absolute value) of the torque of the first motor 26 without considering the rotational direction.

[0036] Then, the phase position calculator 88 calculates (Θ1 + Θ2) / 2, that is, the average value of the first rotation position Θ1 and the second rotation position Θ2, as a third rotation position Θ3 (step S9). The third rotation position Θ3 is the set phase position.

[0037] After step S9, the second motor control unit 84b rotates the first motor 26 to the third rotational position Θ3 (step S10). At this time, the second motor control unit 84b can control the rotational position of the second motor 28 to be fixed. By fixing the rotational position of the second motor 28, the phase adjustment can be performed more reliably. Fig. 3-(4) shows the state after step S10. Thus, the relative position of the movable part 22 in the clearance of the second drive force transmission mechanism 34 and the relative position of the movable part 22 in the clearance of the first drive force transmission mechanism 32 can be matched within a certain range, so that the initial phases of the two drive shafts to be synchronously controlled can be matched with each other.

[0038] The above description was made for the use of the torque of the first motor 26. However, obtaining and comparing the torque of the second motor 28 makes it possible to perform the same phase adjustment as above. When the movable part 22 is moved from the Fig. 3-(3) in the first rotational direction to the third rotational position Θ3, the movable part 22 also moves due to mechanical friction. Therefore, the position of the movable part 22 shown in Fig. 3-(4), from the position of the movable part 22 shown in Fig. 3-(3) is moved away.

[0039] As described above, with the phase adjustment device 70 according to the embodiment, with a simpler structure than the prior art, it is possible to adjust the initial phases of the two drive shafts to be synchronously controlled without providing an additional mechanism. This makes it possible to prevent mechanical distortion, extra loads on the engines, and misalignment due to tilting of the injection mechanism.

[0040] After the phase adjustment device 70 adjusts the phase position of the first motor 26 according to the flow chart in Fig. 4, the motor control unit 84 rotates the first motor 26 and the second motor 28 to adjust their original positions. Fig. 5 is a flowchart for explaining the process for setting the origin position of the first motor 26 and the second motor 28. Here, a stopper 92 (see Fig. 3) installed against the movable part 22 to adjust the initial positions of the first motor 26 and the second motor 28. The position of the movable part 22 limited by the stopper 92 is the initial position of the movable part 22. In fact, the tip of the piston 20, which moves together with the movable part 22, comes into contact with the inner tip of the cylinder 60, causing the movable part 22 to return to its initial position. Thus, the stopper 92 conceptually represents the limitation of the movement of the movable part 22 through the contact between the tip of the piston 20 and the inner tip of the cylinder 60.

[0041] First, the motor control unit 84 causes the first motor 26 and the second motor 28 to rotate synchronously in the same direction of rotation (step S11).

[0042] Next, the engine control unit 84 determines whether the torque acquired by the torque acquisition unit 82 is maximized (step S12). It is considered that the torque is maximized when the torque reaches a certain value. If the torque is not maximized (step S12: NO), control returns to step S11.

[0043] When the torque is maximized (step S12: YES), the motor control unit 84 determines whether the rotational position of the first motor 26, measured by the encoder 74, and the rotational position of the second motor 28, measured by an encoder (not shown), have stopped (step S13). If either rotational position has not stopped (step S13: NO), control returns to step S11.

[0044] When both the rotational position of the first motor 26 and the rotational position of the second motor 28 have stopped (step S13: YES), the rotational position designated as Θ4 is set as the original position of the first motor 26 and the second motor 28 (step S14). Fig. 3-(5) shows the state in step S14 where the movable part 22 is in contact with the stopper 92. Thus, by rotating the first motor 26 and the second motor 28 to the rotational position Θ4, the phase of the first motor 26 within the clearance of the first motor 26 relative to the movable part 22 and the phase of the second motor 28 within the clearance of the second motor 28 relative to the movable part 22 can be adjusted to each other, and the movable part 22 can be moved to the original position. Subsequently, the operation of the injector 10 can be appropriately implemented. [Invention derivable from the embodiment]

[0045] The invention resulting from the above embodiment is described below: (First aspect of the invention)

[0046] A phase adjustment device (70) is one for a drive device (12) having a first motor (26) and a second motor (28) configured to move a movable part (22), a first drive force transmission mechanism (32) configured to convert a rotational force of the first motor (26) into a linear force and transmit the linear force to the movable part (22), and a second drive force transmission mechanism (34) configured to convert a rotational force of the second motor (28) into a linear force and transmit the linear force to the movable part (22). The phase adjustment device (70) comprises a torque acquisition unit (82) configured to acquire a torque of the first motor (26) or the second motor (28), a position acquisition unit (80) configured to acquire a rotational position of the first motor (26),a first motor control unit (84a) configured to rotate the first motor (26) in a first direction of rotation until the torque exceeds a threshold value, and then to rotate the first motor (26) in a second direction of rotation opposite to the first direction of rotation until the torque exceeds the threshold value again, a storage control unit (86) configured to store the rotational position of the first motor (26) when the first motor (26) is rotated in the first direction of rotation and the torque exceeds the threshold value in a storage unit (90) as a first rotational position (Θ1), and to store the rotational position of the first motor (26) when the first motor (26) is rotated in the second direction of rotation and the torque exceeds the threshold value again in the storage unit (90) as a second rotational position (Θ2), a phase position calculator (88) configured to calculate a rotational position of the first motor (26),at which a relative position of the movable part (22) in a clearance of the second drive force transmission mechanism (34) and a relative position of the movable part (22) in a clearance of the first drive force transmission mechanism (32) coincide with each other within a certain range, as a third rotational position (Θ3) on the basis of the first rotational position (Θ1) and the second rotational position (Θ2), and a second motor control unit (84b) configured to rotate the first motor (26) to the third rotational position (Θ3).

[0047] This allows the initial phases of the two drive shafts, which are to be controlled synchronously, to be aligned with each other using a simpler design than the state of the art. This makes it possible to avoid mechanical distortion, extra loads on the engines, and misalignment due to tilting of the injection mechanism.

[0048] The first motor control unit (84a) and the second motor control unit (84b) may be configured to fix a rotational position of the second motor (28) when the first motor (26) is rotated. This allows the phase adjustment of the first motor (26) to be performed more reliably.

[0049] The phase position calculator (88) can be configured to calculate an average of the first rotational position (Θ1) and the second rotational position (Θ2) as the third rotational position (Θ3). This allows the relative positions of the movable part (22) in the clearance between the second motor (28) and the movable part (22) and the relative position of the movable part (22) in the clearance between the first motor (26) and the movable part (22) to be aligned with high precision.

[0050] The first drive force transmission mechanism (32) and the second drive force transmission mechanism (34) may each comprise two pulleys (26p, 36p; 28p, 46p), a belt (38, 44) wound around the two pulleys (26p, 36p; 28p, 46p), a ball screw (36, 42) and a nut (36n, 42n) engaged with the ball screw (36, 42).

[0051] The drive device (12) can be provided in an injection device (10).

[0052] The phase adjustment device (70) may be provided in a control device (16) which is designed to control the injection device (10). (Second aspect of the invention)

[0053] A phase adjustment method is one for a drive device (12) having a first motor (26) and a second motor (28) configured to move a movable part (22), a first drive force transmission mechanism (32) configured to convert a rotational force of the first motor (26) into a linear force and transmit the linear force to the movable part (22), and a second drive force transmission mechanism (34) configured to convert a rotational force of the second motor (28) into a linear force and transmit the linear force to the movable part (22). The phase adjustment method includes a torque acquisition step for acquiring a torque of the first motor (26) or the second motor (28), a position acquisition step for acquiring a rotational position of the first motor (26),a first motor control step for rotating the first motor (26) in a first rotational direction until the torque exceeds a threshold value, a first storage control step for storing the rotational position of the first motor (26) when the first motor (26) is rotated in the first rotational direction and the torque exceeds the threshold value in a storage unit (90) as a first rotational position (Θ1), a second motor control step for rotating the first motor (26) in a second rotational direction opposite to the first rotational direction until the torque exceeds the threshold value again, a second storage control step for storing the rotational position of the first motor (26) when the first motor (26) is rotated in the second rotational direction and the torque exceeds the threshold value again in the storage unit (90) as a second rotational position (Θ2), a phase position calculation step for calculating a rotational position of the first motor (26),wherein a relative position of the movable part (22) in a clearance of the second drive force transmission mechanism (34) and a relative position of the movable part (22) in a clearance of the first drive force transmission mechanism (32) coincide with each other within a certain range, as a third rotational position (Θ3) based on the first rotational position (Θ1) and the second rotational position (Θ2), and a third motor control step for rotating the first motor (26) to the third rotational position (Θ3).

[0054] This allows, with a simpler design than the state of the art, the initial phases of the two drive shafts, which must be controlled synchronously, to be aligned. This makes it possible to avoid mechanical deformation, extra loads on the engines, and misalignment due to tilting of the injection mechanism.

[0055] In the first motor control step, the second motor control step, and the third motor control step, a rotational position of the second motor (28) can be fixed when the first motor (26) is rotated. This makes it possible to perform the phase adjustment of the first motor (26) more reliably.

[0056] In the phase position calculation step, an average of the first rotational position (Θ1) and the second rotational position (Θ2) can be calculated as the third rotational position (Θ3). This allows the relative position of the movable part (22) in the clearance between the second motor (28) and the movable part (22) and the relative position of the movable part (22) in the clearance between the first motor (26) and the movable part (22) to be aligned with each other with high precision.

[0057] The first drive force transmission mechanism (32) and the second drive force transmission mechanism (34) may each comprise two pulleys (26p, 36p; 28p, 46p), a belt (38, 44) wound around the two pulleys (26p, 36p; 28p, 46p), a ball screw (36, 42) and a nut (36n, 42n) engaged with the ball screw (36, 42).

[0058] The drive device (12) can be provided in an injection device (10).

Claims

[1] A phase adjustment device (70) for a drive device (12) having a first motor (26) and a second motor (28) configured to move a movable part (22), a first drive force transmission mechanism (32) configured to convert a rotational force of the first motor into a linear force and to transmit the linear force to the movable part, and a second drive force transmission mechanism (34) configured to convert a rotational force of the second motor into a linear force and to transmit the linear force to the movable part, the phase adjustment device comprising: a torque procurement unit (82) configured to procure a torque of the first motor or the second motor, a position acquisition unit (80) configured to acquire a rotational position of the first motor, a first motor control unit (84a) configured to rotate the first motor in a first direction of rotation until the torque exceeds a threshold value, and then to rotate the first motor in a second direction of rotation opposite to the first direction of rotation until the torque again exceeds the threshold value, a storage control unit (86) configured to store the rotational position of the first motor when the first motor is rotated in the first rotational direction and the torque exceeds the threshold value in a storage unit (90) as a first rotational position (Θ1) and to store the rotational position of the first motor when the first motor is rotated in the second rotational direction and the torque exceeds the threshold value again in the storage unit as a second rotational position (Θ2), and a phase position calculator (88) configured to calculate a rotational position of the first motor, at which a relative position of the movable part in a play of the second drive force transmission mechanism and a relative position of the movable part in a play of the first drive force transmission mechanism coincide with each other within a certain range, as a third rotational position (Θ3) on the basis of the first rotational position and the second rotational position, and a second motor control unit (84b) configured to rotate the first motor to the third rotational position. [2] The phase adjusting device according to claim 1, wherein the first motor control unit and the second motor control unit are configured to fix a rotational position of the second motor when the first motor is rotated. [3] The phase adjusting device according to claim 1 or 2, wherein the phase position calculator is configured to calculate an average of the first rotational position and the second rotational position as the third rotational position. [4] The phase adjusting device according to any one of claims 1 to 3, wherein the first driving force transmission mechanism and the second driving force transmission mechanism each comprise two pulleys (26p, 36p; 28p, 42p), a belt (38, 44) wound around the two pulleys, a ball screw (36, 42) and a nut (36n, 42n) engaged with the ball screw. [5] The phase adjustment device according to one of claims 1 to 4, wherein the drive device is provided in an injection device (10). [6] The phase adjustment device according to claim 5, wherein the phase adjustment device is provided in a control device (16) configured to control the injection device. [7] A phase adjustment method for a drive device (12) having a first motor (26) and a second motor (28) configured to move a movable part (22), a first drive force transmission mechanism (32) configured to convert a rotational force of the first motor into a linear force and transmit the linear force to the movable part, and a drive force transmission mechanism (34) configured to convert a rotational force of the second motor into a linear force and transmit the linear force to the movable part, the phase adjustment method comprising: a torque acquiring step for acquiring a torque of the first motor or the second motor, a position obtaining step for obtaining a rotational position of the first motor, a first motor control step for rotating the first motor in a first direction of rotation until the torque exceeds a threshold value, a first storage control step for storing the rotational position of the first motor when the first motor is rotated in the first rotational direction and the torque exceeds the threshold value in a storage unit (90) as a first rotational position (Θ1), a second motor control step for rotating the first motor in a second direction of rotation opposite to the first direction of rotation until the torque again exceeds the threshold value, a second storage control step for storing the rotational position of the first motor when the first motor is rotated in the second rotational direction and the torque again exceeds the threshold value in the storage unit as a second rotational position (Θ2), a phase position calculation step for calculating a rotational position of the first motor, in which a relative position of the movable part in a play of the second drive force transmission mechanism and a relative position of the movable part in a play of the first drive force transmission mechanism coincide with each other within a certain range, as a third rotational position (Θ3) on the basis of the first rotational position and the second rotational position, and a third motor control step for rotating the first motor to the third rotation position. [8] The phase adjusting method according to claim 7, wherein in the first motor control step, the second motor control step and the third motor control step, a rotational position of the second motor is fixed when the first motor is rotated. [9] The phase adjusting method according to claim 7 or 8, wherein in the phase position calculating step, an average of the first rotational position and the second rotational position is calculated as the third rotational position. [10] The phase adjustment method according to any one of claims 7 to 9, wherein the first driving force transmission mechanism and the second driving force transmission mechanism each comprise two pulleys (26p, 36p; 28p, 42p), a belt (38, 44) wound around the two pulleys, a ball screw (36, 42) and a nut (36n, 42n) engaged with the ball screw. [11] The phase adjustment method according to any one of claims 7 to 10, wherein the driving device is provided in an injection molding device (10)

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