Manufacturing apparatus control method, manufacturing system, control apparatus, and molded article manufacturing method

Abstract

The present application relates to a manufacturing apparatus control method, a manufacturing system, a control apparatus, and a molded article manufacturing method. A manufacturing apparatus includes a nozzle, an injection cylinder, an injection plunger, a plunger pressing member, and a movable unit for moving the plunger pressing member. The movable unit has a ball screw including a moving member and a screw shaft, and the moving member is movable along the screw shaft to a first position, a second position, and a third position. A central processing unit (CPU) of the control apparatus controls the movable unit to move the moving member to the third position in a repeated injection operation in which the moving member moves between the first position and the second position.

Description

Technical Field

[0001] This disclosure relates to manufacturing equipment that uses molten resin and includes a ball screw, such as an injection molding machine. Background Technology

[0002] Manufacturing equipment that uses injection molding to produce molded articles made of resin is known. In such equipment, molten resin is injected into the cavity of a mold using a screw, plunger, etc. The molten resin is cooled and solidified in the mold. After solidification, the mold is opened, and the molded product is removed from the mold. Molded products are mass-produced by repeating this series of operations from injecting molten resin to ejecting the molded product. Examples of manufacturing equipment using injection molding include pre-plasticized plunger-type equipment and in-line screw-type injection molding equipment.

[0003] Japanese Patent Application Publication 2006-256278 discusses a piston drive device that includes a cylinder for storing plasticized synthetic resin material, a piston disposed in the cylinder for extruding the plasticized synthetic resin material from the cylinder, a ball screw mechanism having a nut disposed on the piston and a lead screw shaft screwed to the nut, and a motor for driving the lead screw shaft to rotate.

[0004] In a ball screw mechanism, balls are positioned in the space between the screw shaft and the nut, and this space is filled with grease. The grease circulates around the balls and has the function of reducing surface damage (fretting wear) that occurs when the two objects (balls and screw shaft or nut) repeatedly slide back and forth.

[0005] In the piston drive device discussed in Japanese Patent Application Publication 2006-256278, if resin injection is repeated with small strokes, the ball screw mechanism may be damaged, resulting in injection operation failure. Summary of the Invention

[0006] Some embodiments of this disclosure are intended to provide a technique that helps reduce ball screw damage even when injection operations are repeated with small strokes in injection molding.

[0007] According to one aspect of this disclosure, a method for controlling a manufacturing apparatus includes: an injection nozzle configured to inject resin; an injection cylinder configured to store resin to be supplied to the injection nozzle; an injection plunger configured to press the resin stored in the injection cylinder; and a movable unit configured to move the injection plunger, wherein the movable unit has a ball screw, the ball screw including a moving member and a screw shaft, the moving member being configured to move along a direction of movement of the injection plunger, and the screw shaft being configured to rotate to move the moving member, wherein the moving member is capable of moving to at least a first position, a second position, and a third position along the direction of the screw shaft; the control method includes: performing a first injection operation by moving the moving member, and performing a second injection operation after the first injection operation. The second injection operation, and a third injection operation performed after the second injection operation; wherein the first position is the position of the moving member when the amount of resin to be injected in the second injection operation is stored in the injection cylinder; wherein the second position is the position of the moving member when the injection of resin from the injection cylinder is completed in the second injection operation; wherein the third position is a position where a first distance from the position of a portion of the moving member in the second position to the position of said portion of the moving member in the third position is greater than a second distance from the position of said portion of the moving member in the first position to the position of said portion of the moving member in the second position; and wherein the moving member is moved to the third position during the interval between the first injection operation and the third injection operation.

[0008] Other features of the embodiments will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a schematic cross-sectional view of an injection device according to a first exemplary embodiment.

[0010] Figure 2 This is a diagram illustrating a method for manufacturing a molded article using an injection apparatus according to a first exemplary embodiment.

[0011] Figure 3 The figure includes a diagram illustrating a method for manufacturing a molded article using an injection apparatus according to a first exemplary embodiment.

[0012] Figure 4 This is a diagram illustrating a method for manufacturing a molded article using an injection apparatus according to a first exemplary embodiment.

[0013] Figure 5 The figure includes a diagram illustrating a method for manufacturing a molded article using an injection apparatus according to a second exemplary embodiment.

[0014] Figure 6 The figure includes a diagram illustrating a method for manufacturing a molded article using an injection apparatus according to a third exemplary embodiment.

[0015] Figure 7 This is a diagram illustrating a method for manufacturing a molded article using an injection apparatus according to a fourth exemplary embodiment.

[0016] Figure 8A and Figure 8B This is a schematic cross-sectional view showing a valve unit according to a fourth exemplary embodiment.

[0017] Figure 9A and Figure 9B This is a schematic diagram of the resin pressure in the resin flow path on the injection plunger side and the resin pressure in the resin flow path on the plasticizing screw side during the injection molding cycle according to the fourth and fifth exemplary embodiments.

[0018] Figure 10 This is a diagram illustrating a display unit according to a first exemplary embodiment. Detailed Implementation

[0019] In the following description, exemplary embodiments will be described with reference to the accompanying drawings.

[0020] In the accompanying drawings referenced in the following description of exemplary embodiments, unless otherwise specified, elements indicated by the same reference numerals have the same function.

[0021] Figure 1 This is a schematic cross-sectional view of a manufacturing system 1 according to a first exemplary embodiment. The manufacturing system 1 includes a manufacturing apparatus 100 and a control apparatus 200. The manufacturing apparatus 100 is a pre-plasticized plunger-type injection molding apparatus for manufacturing resin molded articles, and includes a plasticizing unit 111, an injection unit 112, and a movable unit 101. The control apparatus 200 is an example of a control unit capable of controlling the components included in the injection plunger 4 and the movable unit 101 of the manufacturing apparatus 100. The control apparatus 200 includes, for example, one or more computers having a processor.

[0022] <Description of the plasticizing unit>

[0023] Plasticizing unit 111 plasticizes the resin material delivered to plasticizing unit 111 and supplies molten resin to injection unit 112 via connecting member 5. Injection unit 112 injects the molten resin supplied from plasticizing unit 111 into mold (not shown) to supply molten resin into the mold.

[0024] The plasticizing unit 111 includes a hopper (not shown), a plasticizing screw 6, a plasticizing cylinder 7, and a plasticizing drive unit 22. For example, granular resin material is fed into the hopper. The resin material is a thermoplastic resin. The plasticizing cylinder 7 is heated by a heater (not shown) to a temperature that plasticizes the supplied resin material. The plasticizing screw 6 is disposed inside the plasticizing cylinder 7. The plasticizing screw 6 is a rotatable screw. The plasticizing screw 6 has a diameter of, for example, 17 millimeters (mm).

[0025] The plasticizing drive unit 22 includes a reduction gear 20 and a plasticizing motor 21, which serves as an example of a drive source, and is configured to drive the plasticizing screw 6 to rotate via a coupling 220. The plasticizing motor 21 is controlled by a control device 200. The plasticizing screw 6 plasticizes and melts the resin material supplied to the gap between the plasticizing screw 6 and the plasticizing cylinder 7, and moves the resin material toward the front end of the plasticizing screw 6.

[0026] <Injection Unit Description>

[0027] The injection unit 112 includes an injection cylinder 3, an injection plunger 4, a connecting member 5, a check valve 8, and a movable unit 101. The injection cylinder 3 and the injection plunger 4 can be made of metal, such as high-speed steel or hard alloy.

[0028] The injection cylinder 3 has a supply port S for supplying molten resin and a nozzle N for injecting molten resin. The nozzle N is an example of an injection port and is the axial front end of the injection cylinder 3. Contacting the nozzle N with a mold (not shown) will make the interior of the injection cylinder 3 and the interior of the mold communicate with each other.

[0029] The plasticizing cylinder 7 and the injection cylinder 3 are connected via a connecting member 5. The connecting member 5 has a check valve 8, which acts as a valve connected to the supply port S, preventing molten resin from flowing back from the supply port S to the outside of the injection cylinder 3 (i.e., not flowing into the plasticizing unit 111). The check valve 8 prevents molten resin from flowing out of the injection cylinder 3 via the supply port S.

[0030] Check valve 8 is connected to the supply port S in a direction that prevents molten resin from flowing backward from injection cylinder 3 to plasticizing screw 6. When check valve 8 is connected to supply port S, molten resin flows in flow path 31 and flow path 32 in the forward direction from plasticizing cylinder 7 to injection cylinder 3, thus preventing reverse flow from injection cylinder 3 to plasticizing cylinder 7. Flow path 31 and flow path 32 are the flow paths through which molten resin flows. The resin plasticized and melted by plasticizing screw 6 is supplied to injection cylinder 3 via check valve 8 and supply port S of injection cylinder 3. The molten resin supplied from plasticizing screw 6 is stored inside injection cylinder 3. Supply port S may be equipped with an on / off valve instead of check valve 8.

[0031] Plasticized and molten resin flows from plasticizing cylinder 7 into injection cylinder 3 via flow paths 31 and 32 in connecting member 5 and is stored in injection cylinder 3.

[0032] Inside the injection cylinder 3, a switching valve (not shown) is located near the nozzle N. The switching valve changes position between a position allowing injection of molten resin from the nozzle N (open position) and a position preventing injection of molten resin from the nozzle N (closed position). The switching valve prevents molten resin from flowing out of the nozzle N (injection port) from the injection cylinder 3. The switching valve is controlled by the control device 200. A check valve 8 can be located outside the injection cylinder 3 or inside the mold. Furthermore, a check valve 8 located outside the injection cylinder 3 and a check valve 8 located inside the mold can be used in combination.

[0033] As an example of the case where the check valve 8 is located outside the injection cylinder 3, a shut-off nozzle unit can be used; as an example of the case where the check valve 8 is located inside the mold, a hot runner unit can be used.

[0034] <Description of the movable unit>

[0035] Figure 2 From Figure 1 A schematic cross-sectional view of the injection unit 112 in this exemplary embodiment, viewed from the negative (-)Y direction. The movable unit 101 has a ball screw 15. The injection drive unit 25 includes a reduction gear 24 and an injection motor 23, as an example of a drive source, and is configured to drive the screw shaft 13 to rotate via a coupling 250. The ball screw 15 includes a moving member 14 (e.g., a ball screw nut 10) and the screw shaft 13. The screw shaft 13 rotates to move the moving member 14. The injection motor 23 is, for example, a rotary motor and is controlled by a control device 200. The front side of the screw shaft 13 is held by a front block 67 including a bearing, and the rear side of the screw shaft 13 is held by a rear block 66 including a bearing.

[0036] The movable component 14 includes a ball screw nut 10, an injection drive component 19 (also referred to as a moving block), and a plunger pressing component 9. The ball screw nut 10 is connected to and secured to the injection drive component 19, and the injection drive component 19 is connected to and secured to the plunger pressing component 9. The injection drive component 19 is also connected to... Figure 1 The linear guide block 11 shown slides and moves on the linear guide rail 12. With this configuration, the plunger pressing member 9 can move back and forth by the rotation of the injection motor 23. At least two of the plunger pressing member 9, ball screw nut 10, injection drive member 19 and linear guide block 11 that move together can be integrated into a single member as the moving member 14.

[0037] The plunger pressing member 9 is formed separately from the injection plunger 4, and the plunger pressing member is an independent component of the injection plunger 4. That is, the plunger pressing member 9 can contact and separate from the injection plunger 4.

[0038] The plunger pressing member 9 has a spherical surface (e.g., on its front end 9a, which contacts the injection plunger 4) on the side. Figure 3 As shown in the exemplary embodiment, the radius of the sphere is R50. On the other hand, the outer peripheral surface of the injection plunger 4 and the inner peripheral surface of the injection cylinder 3 form a sliding fit, and a fit gap of 2 micrometers (μm) to 50 micrometers is provided between them to prevent leakage of molten resin and engagement between the injection plunger 4 and the injection cylinder 3. In this exemplary embodiment, a plunger with a diameter of 6 mm is used as the injection plunger 4.

[0039] <Instructions for Operation>

[0040] In the following text, the direction of movement of injection cylinder 3 is referred to as the X direction. The Y direction is orthogonal to the X direction, and the Z direction is orthogonal to both the Y and X directions. The positive (+)X direction is the forward direction, and the negative (-X) direction is the backward direction.

[0041] The plunger pressing member 9 moves in the X direction driven by the injection motor 23, thereby contacting and separating from the injection plunger 4. That is, the plunger pressing member 9 is driven by the injection motor 23 to move in the +X direction, thereby pressing the injection plunger 4 in the +X direction, causing the injection plunger 4 in contact with the plunger pressing member 9 to move in the +X direction. Furthermore, the plunger pressing member 9 is driven by the injection motor 23 to move in the -X direction, thereby separating from the injection plunger 4. In other words, the +X direction is the direction in which the plunger pressing member 9 presses the injection plunger 4, and the -X direction is the direction in which the plunger pressing member 9 separates from the injection plunger 4.

[0042] The movement of the injection plunger 4 across the plunger pressing member 9 in the -X direction is restricted by the contact between the plunger pressing member 9 and the injection plunger 4. The movement of the injection plunger 4 across the contact surface of the injection cylinder 3 in the +X direction is restricted by the contact between the stepped portion 41 and the injection cylinder 3.

[0043] The injection plunger 4 is moved backward by the molten resin flowing into the injection cylinder 3. The operation of moving the plunger pressing member 9 to the appropriate position in the -X direction by the movable unit 101 allows the amount of resin that can be stored in the injection cylinder 3 to be set, thereby enabling the metering of the molten resin.

[0044] Next, the positional relationship between the injection cylinder 3, the injection plunger 4, and the moving member 14 when manufacturing a molded article using the manufacturing equipment 100 according to the first exemplary embodiment will be described. Figure 3 Showing from Figure 1A schematic cross-sectional view of the injection cylinder 3, injection plunger 4, plunger pressing member 9 and injection driving member 19 in this exemplary embodiment, viewed in the Y-direction.

[0045] <Instructions for Injection Procedure>

[0046] exist Figure 3 In the diagram, position A shows the position (injection completion position) where the injection plunger 4 is moved forward by the plunger pressing member 9 due to the rotation of the injection motor 23, thus completing the injection of molten resin stored in the injection cylinder 3. In this state, the plunger pressing member 9 and the injection plunger 4 are in contact with each other. Here, the position 9a of the front end of the plunger pressing member 9 (which is part of the moving member 14) at position A is called the "second position". The operation of the injection plunger 4 injecting molten resin stored in the injection cylinder 3 is called an "injection operation". During repeated injection operations, a certain injection operation is called the "first injection operation", the injection operation performed after the first injection operation is called the "second injection operation", and the injection operation performed after the second injection operation is called the "third injection operation".

[0047] In this exemplary embodiment, an example case of elastomeric molding that does not require a pressure holding process is described, and the injection completion position is set within 5 mm relative to the advance limit position, which is the limit of the advance stroke of the injection plunger 4 (e.g., 70 mm). The injection completion position may be a position where pressure control has been completed, or it may be a position that has been stored as the injection completion position based on feedback from the control unit of the injection molding machine regarding the position where pressure control has been completed for each injection.

[0048] In elastomer molding, the residual resin pressure in injection cylinder 3 is low after metering is completed; even if the plunger pressing member 9 retracts, the injection plunger 4 remains in the injection completion position. That is, when the position where pressure control has been completed is used as the injection completion position, control is performed at a pressure that allows only the plunger pressing member 9 to retract while the injection plunger 4 remains in the injection completion position.

[0049] Position B is a diagram showing the "retracted position," which is the position where the plunger pressing member 9 has been retracted in the -X direction by the moving member 14. In this state, the plunger pressing member 9 and the injection plunger 4 are separated from each other, and only the plunger pressing member 9 is moved by a stroke L3 in the -X direction. The position of the tip 9a of the plunger pressing member 9 in position B is called the "third position," and the operation of moving the moving member 14 to the third position is called a "micro-motion operation."

[0050] When the plunger pressing member 9 moves forward by a stroke corresponding to the product of the lead and the number of revolutions of the ball screw, the balls in the helical groove of the ball screw rotate one revolution. The lead is the distance that one of the screw shaft and the nut travels axially when the other rotates one revolution.

[0051] The number of revolutions represents the number of rotations required for the ball (not shown) to return to its original position in the helical groove. In the case of a ball screw with a lead of 5 mm and three revolutions, the stroke L3 is 15 mm (5 mm × 3).

[0052] Since the distance is set such that the stroke L3 of the plunger pressing member 9 includes the stroke L1 required for injection, the stroke L2, which is the amount of movement in the micro-motion operation, can be derived from L3-L1. More specifically, since the stroke L1 required for injection is 5 mm and the stroke L3 is 15 mm, the stroke L2, which is the amount of movement in the micro-motion operation, is 10 mm (15 mm - 5 mm).

[0053] <Instructions for Measurement Operation>

[0054] Position C is a schematic diagram showing the "metering start position," which is the position just before the molten resin flows into the injection cylinder 3. In this state, the injection plunger 4 and the plunger pressing member 9 are separated from each other.

[0055] Position D is a diagram showing the "metering completion position," which is the position where the amount of molten resin to be injected has been stored in the injection cylinder 3 and metering has been completed. In this state, the injection plunger 4 and the plunger pressing member 9 are in contact with each other. The position of the front end 9a of the plunger pressing member 9 at the metering completion position is referred to as the "first position," and the operation from position C to position D in the first exemplary embodiment is referred to as the "metering operation."

[0056] The plunger pressing member 9, which is in the metering start position, is located at a position that advances along the +X direction from the position where the plunger pressing member 9 is in the metering completion position. The position of the front end 9a of the plunger pressing member 9 in the metering start position is called the "fifth position".

[0057] In the metering operation, the plunger pressing member 9 presses the injection plunger 4 along the +X direction, and the molten resin flows into the injection cylinder 3 under a predetermined back pressure applied to the molten resin. During this operation, the control device 200 operates the movable unit 101 for moving the plunger pressing member 9 in a manner that maintains the pressure inside the injection cylinder 3 at a constant pressure (e.g., a back pressure of 1 MPa). More specifically, the control device 200 rotates the plasticizing screw 6, moving the injection plunger 4 backward along the -X direction while balancing the pressure of the molten resin flowing into the injection cylinder 3 with the back pressure. After the injection plunger 4 has reached the predetermined metering position, the rotation of the plasticizing screw 6 is stopped, and the metering operation ends.

[0058] During the metering operation, the front end 9a of the plunger pressing member 9 retracts from the injection completion position to the metering completion position, a distance of stroke L1. Stroke L1 is, for example, 5 mm.

[0059] like Figure 4 As shown, after the metering operation is completed, check valve 8 is closed to shut off the connection between flow paths 31 and 32.

[0060] Here, the journey L3 from the second position to the third position is called the "first distance", and the journey L1 from the first position to the second position is called the "second distance".

[0061] <Explanation of the pullback operation>

[0062] Figure 3 Position E in the diagram illustrates the position where a "back suction operation" has been performed. The back suction operation is the process of the plunger pressing member 9 retracting further by a predetermined amount in the -X direction, opposite to the nozzle N, after the metering operation has been completed and the connection between flow paths 31 and 32 has been closed. The position where the plunger pressing member 9 retracts during the back suction operation is called the back suction position. In this state, the injection plunger 4 and the plunger pressing member 9 can be separated from each other or can be in contact with each other. The back suction operation is the process of moving the injection plunger 4 backward to reduce the internal resin pressure inside the injection cylinder 3 after the metering operation is completed.

[0063] During metering operations, internal pressure is applied to the molten resin stored in injection cylinder 3. Therefore, if the pressure of the molten resin within injection cylinder 3 remains high, leakage (dripping) of the molten resin from the tip of the injection nozzle or rapid ejection (jetting) of the molten resin from the tip of the injection nozzle during the injection operation occurs. Backflow operation reduces molten resin leakage and jetting.

[0064] The position of the front end 9a of the plunger pressing member 9 in the suction position is called the "fourth position". During the suction operation, the front end 9a of the plunger pressing member 9 retracts from the metering completion position to the suction position where the plunger pressing member 9 has moved a stroke L4. The stroke L4 from the metering completion position to the suction position is called the "third distance". The stroke L4 is set to, for example, 2mm to 3mm.

[0065] As described above, the injection plunger 4 and the plunger pressing member 9 are designed to be separable from each other, thereby reducing molding defects such as voids and silver streaks caused by air entrainment into the molten resin in the injection cylinder 3 during metering and back suction operations.

[0066] <Next injection procedure>

[0067] Figure 3Position F in the diagram shows the injection completion position when the injection plunger 4 has been pressed down by the plunger pressing member 9 and moved forward in the +X direction from the state shown in position E, and the injection of the molten resin stored in the injection cylinder 3 has been completed. In this state, the plunger pressing member 9 and the injection plunger 4 are in contact with each other.

[0068] Using the above structure, in the molding process, the plunger pressing member 9 can move with a stroke greater than or equal to the stroke that allows the grease to circulate, and can perform a continuous molding process with a small stroke without stopping the equipment, while preventing wear and damage to the ball screw.

[0069] Reference Figure 5 An injection device according to a second exemplary embodiment is described. In this exemplary embodiment, descriptions of the same items as in the first exemplary embodiment will be simplified or omitted. Figure 5 In the diagram, positions A to F are illustrations of a method for manufacturing a molded article using the manufacturing equipment 100 according to this exemplary embodiment. Positions A to F schematically show cross-sectional views of the injection cylinder 3, injection plunger 4, and plunger pressing member 9 in this exemplary embodiment in a time sequence. The positional relationship between the injection plunger 4 and the plunger pressing member 9 relative to the injection cylinder 3 is shown in a time sequence at positions A to F, and the movement from position A to position F is repeated during the molding process.

[0070] Figure 5 Position A in the diagram shows the position where the injection plunger 4 has moved forward in the +X direction and the injection of molten resin stored in the injection cylinder 3 has been completed. The position of the front end 9a of the plunger pressing member 9 in position A is called the "second position".

[0071] The user sets the measurement completion position and injection completion position by inputting values ​​into the operation screen. The control device 200 calculates the stroke L1 based on the user-set measurement completion and injection completion positions, and executes control to switch to a micro-motion operation mode if the relationship between stroke L1 and a preset stroke L3 is L1 < L3. For example, stroke L1 is set to 5mm, and stroke L3 is set to 15mm. The control device 200 can execute L3 - L1 to calculate stroke L2, and if L1 < L2, the control device 200 can switch to a micro-motion operation mode.

[0072] Figure 5Position B in the diagram shows the position where the plunger pressing member 9 has been retracted by a micro-motion operation (retraction completion position). The stroke L3 from the injection completion position to the retraction completion position is preset, and the micro-motion operation is performed when the micro-motion operation mode is set. In this operation, since the plunger pressing member 9 and the injection plunger 4 are separated from each other, only the plunger pressing member 9 moves by a stroke L2. The position of the front end 9a of the plunger pressing member 9 in position B is called the "third position".

[0073] Figure 5 Position C in the diagram shows the position where the plunger pressing member 9 has moved forward from the retracted position and completed its movement towards the metering start position. In this position, the plunger pressing member 9 and the injection plunger 4 are separated from each other. The position of the front end 9a of the plunger pressing member 9 in position C is referred to as the "fifth position". Then, the pressure of the molten resin flowing into the injection cylinder 3 causes the injection plunger 4 to move backward, and the injection plunger 4 contacts and abuts against the plunger pressing member 9.

[0074] Figure 5 Position D in the diagram shows the position where the injection plunger 4 and the plunger pressing member 9 have come into contact and the metering of the molten resin has been completed. The position 9a of the front end of the plunger pressing member 9 in position D is called the "first position". The completion of metering is determined by detecting, based on the current value of the servo motor, the state in which the injection plunger 4 has pressed the plunger pressing member 9 by the pressure of the molten resin stored in the injection cylinder 3. Then, stop. Figure 4 The rotation of the plasticizing screw 6 completes the metering operation. Alternatively, different sensors can be used as detection devices to determine the completion of metering.

[0075] The mating clearance between the injection plunger 4 and the injection cylinder 3 can be set, for example, from 2 μm to 50 μm. In some cases during continuous molding operations, the sliding resistance between the injection plunger 4 and the injection cylinder 3 changes when the injection plunger 4 is pushed upward and moved backward by the molten resin that has flowed into the clearance. In this exemplary embodiment, a detection time T is used. Time T is the period from the moment when the plunger pressing member 9 is in the metering start position shown in position C and the rotation of the plasticizing screw 6 begins, to the moment when the plunger pressing member 9 is in the metering completion position shown in position D and the detection of the injection plunger 4 pressing the plunger pressing member 9 is performed. The control device 200 compares time T with a preset predetermined time. If time T exceeds the predetermined time, the control device 200 determines that molten resin has flowed into the mating clearance between the injection plunger 4 and the injection cylinder 3, that is, engagement has occurred. Based on this determination, the control device 200 can issue a warning to remind maintenance. For example, the predetermined time is 1 second.

[0076] As described above, even when the injection plunger 4 has moved backward to the metering completion position and molten resin flows into the injection cylinder 3, it is not necessary to stop the injection equipment to circulate the grease from the ball screw. In other words, the injection equipment can move with a stroke that reduces fretting wear during the intervals of continuous molding performed with small strokes. Since the injection plunger 4 is not forced to move backward, molding defects caused by air entrainment are reduced, thereby improving the yield associated with molded article manufacturing. Position E is shown in relation to... Figure 3 The same "pull-back operation" has been performed at position E in the diagram. Figure 5 The position F in the middle is shown to be related to Figure 3 The diagram shows the injection completion location in the same manner as shown at position F in the middle.

[0077] Reference Figure 6 An injection device according to a third exemplary embodiment is described. In the third exemplary embodiment, descriptions of the same items as in the first and second exemplary embodiments will be simplified or omitted.

[0078] exist Figure 6 In the diagram, positions A to E are schematic cross-sectional views illustrating the injection cylinder 3, injection plunger 4, and plunger pressing member 9 according to a third exemplary embodiment. The positional relationship between the injection plunger 4 and the plunger pressing member 9 relative to the injection cylinder 3 is shown in a time sequence from position A to position E, and the movements shown in positions A to E are repeated in this sequence during the molding process.

[0079] Position A is a diagram showing the position where the injection plunger 4 has moved forward in the +X direction and the injection of molten resin stored in the injection cylinder 3 has been completed. The position of the front end 9a of the plunger pressing member 9 in position A is referred to as the "second position".

[0080] In this state, the molten resin remaining in the flow path after injection is under high pressure due to the residual pressure after injection. For example... Figure 4 As shown, when injection is complete, check valve 8 is closed to prevent molten resin from flowing back into plasticizing screw 6 during injection. Then, check valve 8 opens, as... Figure 1 As shown. The check valve 8 is configured to open and close by air actuation. When the flow path is opened, the pressure of the molten resin remaining in the flow path under residual pressure is released. Furthermore, after opening the check valve 8, the plasticizing screw 6 is rotated in the opposite direction to that during plasticizing and melting.

[0081] Figure 6Position B in the diagram shows the position where the plunger pressing member 9 has retracted from the second position in the -X direction and the movement of the plunger pressing member 9 towards the metering start position is complete. The position of the front end 9a of the plunger pressing member 9 in position B is called the "fifth position". In this state, the plunger pressing member 9 and the injection plunger 4 are separated from each other. Then, the pressure of the molten resin that has flowed into the injection cylinder 3 causes the injection plunger 4 to move backward, and the injection plunger 4 contacts and abuts against the plunger pressing member 9.

[0082] Figure 6 Position C in the diagram shows the position where the injection plunger 4 and the plunger pressing member 9 are in contact with each other and the metering of molten resin has been completed. The position of the front end 9a of the plunger pressing member 9 in position C is called the "first position". The completion of metering is determined by detecting, based on the current value of the servo motor, the state in which the injection plunger 4 has pressed the plunger pressing member 9 with the pressure of the molten resin stored in the injection cylinder 3. Then, stop. Figure 4 The rotation of the plasticizing screw 6 ends the metering operation. Different sensors can be used as detection devices to determine the completion of metering.

[0083] Figure 6 Position D in the diagram shows the position where the micro-motion operation has been performed and the plunger pressing member 9 has retracted. The stroke L3 from the injection completion position to the retraction completion position is preset, and the retraction operation is performed in micro-motion mode. In this operation, since the plunger pressing member 9 and the injection plunger 4 are separated from each other, only the plunger pressing member 9 moves a stroke L2. The position of the front end 9a of the plunger pressing member 9 in position D is called the "third position". Position E is a diagram showing the injection completion position where the injection plunger 4 has been pressed by the plunger pressing member 9 and moved forward in the +X direction from the state shown in position D, and the injection of the molten resin stored in the injection cylinder 3 has been completed. In this state, the plunger pressing member 9 and the injection plunger 4 are in contact with each other.

[0084] During the movement of the plunger pressing member 9 from the metering completion position shown in position C to the retraction completion position shown in position D, a suction operation can be performed by moving the plunger pressing member 9 through the suction position.

[0085] Reference Figure 5 , Figure 7 ,as well as Figure 9A and Figure 9B An injection device according to a fourth exemplary embodiment is described. Figure 7 This is a cross-sectional view showing the resin flow path of a preplasticized injection molding machine equipped with an injection plunger 4 according to this exemplary embodiment.

[0086] Figure 8A and Figure 8BThis is a cross-sectional view showing a valve unit using a ball in this exemplary embodiment. Figure 9A This is a schematic diagram showing the pressure in the resin flow path on the side of the injection plunger 4 and the pressure in the resin flow path on the side of the plasticizing screw 6 during the injection molding cycle of this exemplary embodiment.

[0087] This will describe the operation of opening and closing the resin flow path and performing continuous molding with minute strokes by utilizing a resin flow check valve. For example... Figure 7 as well as Figure 8A and Figure 8B As shown, a ball 33 is provided in the valve unit 34, which is inserted into the resin flow path inside the connecting member 5 that connects the injection plunger 4 and the plasticizing screw 6. When the ball 33 moves toward the plasticizing screw 6, the resin flow path between the flow path 31 on the plasticizing screw 6 side and the flow path 32 on the injection plunger 4 side is closed by the ball 33 being on the valve seat 51. When the ball 33 moves toward the injection plunger 4 side, the ball 33 contacts the valve claw 52. In this state, the resin flow path is opened due to the gap between the contacting ball 33 and the valve claw 52. For example, the diameter of the basic flow path of the connecting member 5 is 5 mm, the diameter of the ball 33 is 6 mm, and the diameter of the valve unit 34 gradually increases to retain the ball 33 inside the valve unit 34.

[0088] Figure 5 Position A in the diagram shows the location where the injection plunger 4 has moved forward and the injection of the molten resin stored in the injection cylinder 3 has been completed. Figure 9A This is a schematic diagram illustrating the resin pressure during the injection molding cycle. In the diagram, the solid line represents the resin pressure in the resin flow path on the side of the injection plunger 4, and the dashed line represents the resin pressure in the resin flow path on the side of the plasticizing screw 6. Figure 9A The time period (1) schematically represents the resin pressure during the process of the injection plunger 4 moving forward and then moving towards the injection completion position. In this process, molten resin flows from the flow path 32 on the side of the injection plunger 4 into the flow path 31 on the side of the plasticizing screw 6 by injection. Figure 8A As shown, due to the inflow of molten resin, the ball 33 in the connecting member 5 moves towards the plasticizing screw 6, and the resin flow path is closed when the ball 33 is located on the valve seat 51. In this state, as... Figure 5 Position A in the middle and Figure 9AAs shown in time period (1), the pressure in the flow path 32 on the injection plunger 4 side increases due to the injection of molten resin, and the inflow of molten resin also increases the pressure in the flow path 31 on the plasticizing screw 6 side. This leads to the closure of the resin flow path and the dispersion of pressure, thereby reducing the pressure. The molten resin in the flow path 32 on the injection plunger 4 side remains in a high-pressure state due to the residual pressure after injection. This exemplary embodiment uses the case of elastomer molding without a pressure holding process as an example, so the residual pressure is equal to or less than 10 MPa, and the pressure difference between the pressure in the flow path 31 on the plasticizing screw 6 side and the pressure in the flow path 32 on the injection plunger 4 side is not large. Next, as Figure 9A As shown in time period (2), the resin flow path is opened to depressurize the molten resin in flow path 32. To perform this operation, the plasticizing screw 6 is rotated in the plasticizing and melting direction. After the pressure in flow path 31 on the side of the plasticizing screw 6 gradually increases and when the pressure in flow path 31 exceeds the pressure of the molten resin in flow path 32 on the side of the injection plunger 4, as... Figure 8B As shown, in the connecting member 5, the ball 33 moves toward the injection plunger 4 and contacts the valve claw 52, ​​thereby opening the resin flow path through the gap between the ball 33 and the valve claw 52. In this state, due to the inflow of plasticized molten resin, the molten resin flows from the flow path 32 on the injection plunger 4 side into the flow path 31 on the plasticizing screw 6 side, and the pressure is equalized. In this state, because the pressure difference is not large, the ball 33 does not close the resin flow path. Furthermore, the plasticizing screw 6 is rotated in the opposite direction to the plasticizing and melting direction. Through this operation, the pressure is relieved on the flow path 32 on the injection plunger 4 side and the flow path 31 on the plasticizing screw 6 side, and the pressure relief is completed.

[0089] Then, as Figure 5 As shown in position B, only the plunger pressing member 9 retracts by a stroke L3. In the case of elastomer molding where pressure holding is not required, there may be almost no... Figure 9A The residual pressure is shown in the middle period (2). In this case, depressurization and retraction of the plunger pressing member 9 can be performed simultaneously. Next, the plunger pressing member 9 is moved forward from the retraction completion position to a position immediately before the injection completion position, as shown. Figure 5 Position C is shown in the diagram. Furthermore, as... Figure 5 Position D and Figure 9A As shown in time segment (3), the resin, plasticized and melted by the rotation of the plasticizing screw 6, flows into the injection cylinder 3 via the resin flow path in the connecting member 5 and is stored within the injection cylinder 3. In this operation, as... Figure 8B As shown, in the connecting member 5, the ball 33 contacts the valve claw 52, ​​and the resin flow path is open. The plunger pressing member 9 retracts by a stroke L1 from the injection completion position to the metering completion position while pressing the injection plunger 4 to apply back pressure to the molten resin stored in the injection cylinder 3.

[0090] In the manner described above, even in a structure where the check valve is opened and closed by resin flow, the metering completion position, the retraction completion position, and the injection completion position can be set, thereby achieving the same effect as the exemplary embodiments described above.

[0091] As a fifth exemplary embodiment, such as Figure 9B As shown, even when pressure control is performed under high pressure conditions, the position where pressure control is completed is set as the injection completion position, and the residual pressure of the molten resin in the flow path 32 on the injection plunger 4 side is much higher, pressure relief can be achieved by repeatedly rotating and reversing the plasticizing screw 6 during pressure relief. When the residual pressure is high, the aforementioned reversal of the plasticizing screw 6 is performed to relieve pressure in the flow path 32 on the injection plunger 4 side and the flow path 31 on the plasticizing screw 6 side. However, the ball 33 from Figure 8B The flow path opening position shown is moved to Figure 8A The flow path is closed as shown. In this case, the plasticizing screw 6 is further rotated and reversed to gradually release the pressure in the resin flow path. By doing so, the same effect as in the exemplary embodiments described above can be obtained.

[0092] <Display Device>

[0093] Next, we will refer to Figure 10 The display unit 201 of the control device 200 is described. The control device 200 causes the display unit 201 (e.g., a monitor or touch screen) to display position information regarding the metering completion position, injection completion position, and retraction completion position of the moving member 14 in the lead screw 13. The display unit 201 may be a device different from the control device 200, or it may be part of the control device 200.

[0094] Position information, for example, is the length from the end of the lead screw 13 to the front end 9a of the moving member 14 in each of the following states: metering completion position, injection completion position, and retraction completion position. The display unit 201 may also have the function of displaying relative positional relationship information, such as the movement distance from the metering completion position to the injection completion position and the movement distance from the injection completion position to the retraction completion position.

[0095] The display unit 201 can receive input from the user. In the measurement position input area 202, the measurement completion position can be input and displayed. In the injection position input area 203, the injection completion position can be input and displayed. In the injection volume input area 204, the injection volume can be input and displayed.

[0096] The control device 200 compares a predetermined value with user-input position information or relative position relationship information, or compares the predetermined value with position information or relative position relationship information calculated by the control device 200 based on the user-input position information and relative position relationship information. For example, the control device 200 calculates the value of the injection volume input area 204 based on the position information input to the metering position input area 202 and the injection position input area 203, and compares it by determining whether the value is less than the distance required for the grease to circulate around the balls in the ball screw 15. If the control device 200 determines that the value of the injection volume input area 204 is less than the distance required for the grease to circulate, the control device 200 causes the display unit 201 to display a warning, or displays a notification that the mode can be changed to perform micro-motion operations during the intervals between consecutive injection operations.

[0097] The user selects whether to apply back pressure during metering using the back pressure yes / no button 205. When the user selects "yes", the control of causing the molten resin to flow into the injection cylinder 3 is executed while the injection plunger 4 is pressed in the +X direction by the plunger pressing member 9 to apply a predetermined back pressure to the molten resin.

[0098] The micro-motion on / off button 206 is used to change whether micro-motion is performed during the intervals between consecutive injection operations. The micro-motion execution frequency selection button 207 is used to select whether micro-motion is performed for each cycle of the injection operation or intermittently. The execution frequency input area 208 is used to specify the number of injection operation cycles at which micro-motion is performed.

[0099] In the micro-motion position input area 209, the completed backward position can be input and displayed. In the micro-motion input area 210, the length of the stroke L2 can be input and displayed.

[0100] In the suction position input area 211, the suction position can be input and displayed. In the suction amount input area 212, the distance of stroke L4 can be input and displayed.

[0101] Even without user intervention, the control device 200 can automatically change to a mode for performing micro-motion operations. The control device 200 can automatically change the position information and relative positional relationship information of the moving member 14, such that the movement distance from the injection completion position to the retraction completion position is greater than the movement distance from the metering completion position to the injection completion position.

[0102] According to this disclosure, even when repeated injection operations are performed with minute strokes, the occurrence of damage to the injection device is reduced.

[0103] This disclosure is not limited to the exemplary embodiments described above, and many variations can be made within the scope of the technical concept of this disclosure. Furthermore, the effects described in the exemplary embodiments are merely an enumeration of some effects arising from this disclosure, and the effects of this disclosure are not limited to those described in the exemplary embodiments.

[0104] In the above exemplary embodiments, the front end 9a of the plunger pressing member 9 has been described as part of the moving member 14. However, the construction is not limited to this. Instead of the front end 9a, the rear end of the plunger pressing member 9, a part of the ball screw nut 10, or a predetermined portion can be used. That is, any portion can be used as long as the distance between different positions of the same part in the moving member 14 can be compared.

[0105] In the above exemplary embodiments, the movable member 14 moves backward in the -X direction during micro-motion operation, but it can also move forward in the +X direction.

[0106] While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation to cover all variations and equivalent structures and functions.

Claims

1. A control method for manufacturing equipment, Manufacturing equipment includes: Injection nozzle, configured for resin injection. The injection cylinder is configured to store the resin to be supplied to the injection nozzle. An injection plunger configured to press the resin stored in the injection cylinder, and A movable unit configured to move an injection plunger includes a ball screw comprising a moving member and a screw shaft. The moving member is configured to move along a direction of movement of the injection plunger, and the screw shaft is configured to rotate to move the moving member. The movable component is capable of moving to at least a first position, a second position, and a third position along the direction of the lead screw axis. Control methods include: The first injection operation, the second injection operation performed after the first injection operation, and the third injection operation performed after the second injection operation are performed by moving the movable component. The first position is the position of the moving component when the amount of resin to be injected in the second injection operation is stored in the injection cylinder. The second position is the position of the moving component when the resin injection from the injection cylinder is completed in the second injection operation. The third position is a position where the first distance from the position of a portion of the moving member in the second position to the position of that portion of the moving member in the third position is greater than the second distance from the position of that portion of the moving member in the first position to the position of that portion of the moving member in the second position. Specifically, the movable component is moved to the third position during the interval between the first injection operation and the third injection operation.

2. The control method according to claim 1, wherein, The movable component is a component that can be separated from the injection plunger.

3. The control method according to claim 2, wherein, When the moving component is in the third position, the moving component and the injection plunger are separated from each other.

4. The control method according to claim 1, wherein, The moving member is moved to the third position while it is being moved from the first position to the second position.

5. The control method according to claim 1, wherein, The moving member is moved to the third position while it is being moved from the second position to the first position.

6. The control method according to claim 1, wherein, The second distance is less than the product of the lead and the number of revolutions of the ball screw.

7. The control method according to claim 1, wherein, The second distance is less than the distance from the position of a portion of the moving member in the third position to the position of the portion of the moving member in the first position.

8. The control method according to claim 1, in, The movable component is also configured to move to the fourth position. The fourth position is located further away from the first position in the direction of plunger movement, on the opposite side of the injection nozzle. In this process, after the amount of resin to be injected is stored in the injection cylinder at the first position, the moving member is moved to the fourth position.

9. The control method according to claim 1, in, The movable component is also configured to move to the fourth position. The fourth position is located further away from the first position in the direction of plunger movement, on the opposite side of the injection nozzle. Specifically, after moving the moving member from the third position to the first position, the moving member is moved to the fourth position.

10. The control method according to claim 1, in, The movable component is also configured to move to the fourth position. The fourth position is located further away from the first position in the direction of plunger movement, on the opposite side of the injection nozzle. The movable component moves via a fourth position during the period from the first position to the third position.

11. The control method according to claim 8, wherein, The third distance from the first position to the fourth position is less than the first distance.

12. The control method according to claim 11, wherein, The third distance is less than the second distance.

13. The control method according to claim 2, wherein, The moving member is separated from the injection plunger during the process of moving the moving member from the first position to the third position.

14. The control method according to claim 2, in, The movable component is also configured to move to the fifth position. The fifth position is located between the first and second positions in the direction of injection plunger movement, and Specifically, when resin is supplied to the injection cylinder while the moving component is separated from the injection plunger, the injection plunger, pressed by the resin, contacts the moving component and moves the moving component from the fifth position to the first position.

15. The control method according to claim 1, wherein, If the second distance is less than the distance required for the grease to circulate around the ball screw, control is executed to change the mode to move the moving member to the third position during the interval between each successive injection operation.

16. A manufacturing system, comprising: Manufacturing equipment; and Control equipment, capable of controlling manufacturing equipment. The manufacturing equipment includes: Injection nozzle, configured for resin injection. The injection cylinder is configured to store the resin to be supplied to the injection nozzle. An injection plunger configured to press the resin stored in the injection cylinder, and The movable unit is configured to move the injection plunger. The movable unit includes a ball screw, which comprises a movable member configured to move along the direction of movement of the injection plunger and a screw shaft configured to rotate to move the movable member. The movable component is capable of moving to at least a first position, a second position, and a third position along the direction of the lead screw axis. Specifically, the first injection operation is performed by moving the movable component, the second injection operation is performed after the first injection operation, and the third injection operation is performed after the second injection operation. The first position is the position of the moving component when the amount of resin to be injected in the second injection operation is stored in the injection cylinder. The second position is the position of the moving component when the resin injection from the injection cylinder is completed in the second injection operation. The third position is a position where the distance from the location of a portion of the moving member in the second position to the location of that portion in the third position is greater than the distance from the location of that portion of the moving member in the first position to the location of that portion of the moving member in the second position. The control device moves the movable component to the third position during the interval between the first injection operation and the third injection operation.

17. The manufacturing system according to claim 16, in, The resin flows into the injection cylinder through a connecting member including a valve unit, and The valve unit is configured to depressurize the inside of the injection cylinder.

18. A control device for controlling manufacturing equipment, Manufacturing equipment includes: Injection nozzle, configured for resin injection. The injection cylinder is configured to store the resin to be supplied to the injection nozzle. An injection plunger configured to press the resin stored in the injection cylinder, and A movable unit configured to move an injection plunger includes a ball screw comprising a moving member and a screw shaft. The moving member is configured to move along a direction of movement of the injection plunger, and the screw shaft is configured to rotate to move the moving member. The movable component is capable of moving to at least a first position, a second position, and a third position along the direction of the lead screw axis. The control equipment includes: One or more processors, configured to control the device: The first injection operation, the second injection operation performed after the first injection operation, and the third injection operation performed after the second injection operation are performed by moving the movable component. The first position is the position of the moving component when the amount of resin to be injected in the second injection operation is stored in the injection cylinder. The second position is the position of the moving component when the resin injection from the injection cylinder is completed in the second injection operation. The third position is the position where the distance from the second position to the third position is greater than the distance from the first position to the second position, and Specifically, the movable component is moved to the third position during the interval between the first injection operation and the third injection operation.

19. The control device according to claim 18, wherein, The one or more processors are further configured to cause the control device to display at least one of position information about a first position, position information about a second position, and position information about a third position on a display device.

20. The control device according to claim 18, wherein, The one or more processors are further configured to cause the control device to display on a display device a relative positional relationship of at least one combination of a first position, a second position, and a third position.

21. The control device according to claim 18, wherein, The one or more processors are further configured to cause the control device to display a notification on a display device regarding a mode that allows the moving member to be moved to a third position during the interval between successive injection operations and a mode that does not allow the moving member to be moved to the third position.

22. The control device according to claim 18, wherein, The one or more processors are further configured to enable the control device to display a button on a display device for switching between a mode of moving the moving member to a third position and a mode of not moving the moving member to the third position during the interval between successive injection operations.

23. A method for manufacturing a molded article, the method comprising: Manufacturing equipment for manufacturing molded articles is controlled by using the control method according to any one of claims 1 to 15; and Resin is injected from the injection nozzle into the mold.

24. A method for manufacturing a molded article, the method comprising injecting resin from an injection nozzle into a mold using a manufacturing system according to claim 16 or 17.

25. A method for manufacturing a molded article, the method comprising injecting resin from an injection nozzle into a mold using a control device according to any one of claims 18 to 22.

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