Injection device

Abstract

Provided is an injection device capable of injecting a constant amount of resin material for each injection process while suppressing an increase in cost due to an increase in the number of components and suppressing entry of air into a cylinder. An injection device (1) includes: a resin material inflow port (13); a drive section (20) that generates a drive force for injecting resin material from an injection port (12); a plunger (17) disposed so as to be able to advance and retreat in the axial direction of a cylinder (11), the plunger (17) retreating by inflow of resin material into the cylinder (11) and advancing in the cylinder (11) to inject resin material filled into the cylinder (11) toward the injection port (12); a push-in member (18) that pushes in the plunger (17) toward the injection port (12) of the cylinder (11); a drive force transmission section (21) for transmitting the drive force generated by the drive section (20) to the push-in member (18); and a control section (25) that controls each section so that inflow of resin material into the cylinder (11) is started and metering of the resin material is completed when a load on the drive section (20) from the push-in member (18) located at a prescribed position reaches a prescribed value.

Description

Technical Field

[0001] This invention relates to an injection device. Background Technology

[0002] An injection molding machine is a device that continuously supplies a constant amount of resin material. Injection molding machines are used, for example, to inject resin material into a mold. In an injection molding machine, for continuous injection of resin material, a metering process following the injection step to supply a constant amount of resin material into the barrel is crucial. This is because even if the same volume of resin material is injected from the injection molding machine, the amount of resin material injected will be inconsistent if the density of the resin material inside the barrel is unstable. In order to accurately inject a constant amount of resin material in a single injection step, the material pressure (barrel pressure) needs to be kept constant during the metering process.

[0003] In the past, in order to maintain a constant material pressure during the metering process, metering methods have been proposed, for example, as follows. One method is to supply resin material while retracting the plunger at a constant speed, and stop the supply of resin material at the point when the plunger reaches a predetermined position (hereinafter also referred to as "conventional method 1"). Another method is to supply resin material while retracting the plunger to maintain a constant material pressure in the barrel, and stop the supply of resin material at the point when the plunger reaches a predetermined position (hereinafter also referred to as "conventional method 2") (see Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 02-120020 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In the aforementioned conventional method 1, the plunger retracts at a constant speed regardless of the resin material supply rate. Therefore, depending on the resin material supply rate, there is a concern that air may enter the barrel, leading to poor molding. In particular, when using a low-viscosity liquid resin such as silicone resin, air is more likely to enter the barrel, thus increasing the likelihood of poor molding. Furthermore, in conventional method 2, the material pressure can be maintained at a constant level from the start of resin material supply to its completion. However, conventional method 2 requires components such as a pressure sensor to measure the material pressure inside the barrel, raising concerns about increased costs due to the increased number of components.

[0009] The purpose of this invention is to provide an injection apparatus that can inject a constant amount of resin material for each injection step while suppressing the entry of air into the barrel and reducing the cost increase due to the increase in the number of components.

[0010] Solution for solving the problem

[0011] One aspect of the present invention is an injection device for injecting resin material from an injection port disposed at the front end of a barrel. The injection device comprises: a resin material inlet for allowing resin material to flow into the barrel; a drive unit for generating a driving force to inject the resin material filled in the barrel from the injection port; a plunger disposed axially along the barrel, the plunger retracting as resin material flows into the barrel from the resin material inlet, and injecting the resin material filled in the barrel toward the injection port by advancing within the barrel; a pusher member for pushing the plunger toward the injection port of the barrel; a drive force transmission unit for transmitting the driving force generated by the drive unit to the pusher member; and a control unit for controlling each unit to cause the resin material to begin flowing into the barrel from the resin material inlet, and to complete the metering of the resin material when the load on the drive unit from the pusher member located at a predetermined position reaches a predetermined value.

[0012] The effects of the invention

[0013] According to the injection apparatus of the present invention, a constant amount of resin material can be injected for each injection step while suppressing the entry of air into the barrel and the increase in cost due to the increase in the number of parts. Attached Figure Description

[0014] Figure 1 This is a diagram illustrating the structure of the injection device 1 according to the first embodiment.

[0015] Figure 2A This is a diagram illustrating the injection and pressure holding processes of the first embodiment.

[0016] Figure 2B This is a diagram illustrating the injection and pressure holding processes of the first embodiment.

[0017] Figure 3A This is a diagram illustrating the metering process of the injection device 1 according to the first embodiment.

[0018] Figure 3B This is a diagram illustrating the metering process of the injection device 1 according to the first embodiment.

[0019] Figure 3C This is a diagram illustrating the metering process of the injection device 1 according to the first embodiment.

[0020] Figure 4 This diagram illustrates the control of adjusting the material pressure of the resin material.

[0021] Figure 5 This diagram illustrates the control for changing the switching position.

[0022] Figure 6A This is a flowchart illustrating the processing procedure of the metering control program executed by the control unit 25 in the first embodiment.

[0023] Figure 6B This is a flowchart illustrating the processing procedure of the metering control program executed by the control unit 25 in the first embodiment.

[0024] Figure 7A This is a diagram illustrating the metering process of the injection device 1A according to the second embodiment.

[0025] Figure 7B This is a diagram illustrating the metering process of the injection device 1A according to the second embodiment.

[0026] Figure 8A This is a flowchart illustrating the processing procedure of the metering control program executed by the control unit 25 in the second embodiment.

[0027] Figure 8B This is a flowchart illustrating the processing procedure of the metering control program executed by the control unit 25 in the second embodiment.

[0028] Figure 9 This is a diagram illustrating the structure of the injection device 1, which describes the deformation method. Detailed Implementation

[0029] The following describes embodiments of the injection device according to the present invention. The accompanying drawings in this specification are schematic depictions, and the shapes, scales, aspect ratios, etc., of various parts have been altered or exaggerated relative to the actual object for ease of understanding, etc. Furthermore, in the accompanying drawings of this specification, [the following will be noted / discussed]. Figure 1 The front-to-back (horizontal) direction of the injection device 1 shown is designated as the X direction. Furthermore, the rear (right) direction within the X direction is designated as the X1 direction, and the front (left) direction is designated as the X2 direction. In addition, in this specification, the "~ direction" will also be appropriately referred to as the "~ side".

[0030] (First Implementation)

[0031] The injection unit 1 and the mold clamping device of the first embodiment together constitute an injection molding machine (neither shown). The injection molding machine includes a base (not shown), and the injection unit 1 and the mold clamping device disposed on the base. The injection unit 1 is a device for supplying resin material to the mold clamping device. In the injection unit 1, the molding cycle for injecting the resin material filled into the barrel 11 (described later) into the mold clamping device includes a metering step, an injection step, and a holding pressure step. The mold clamping device has a mold that can be opened and closed, and the mold clamping device manufactures a molded article by pressurizing and heating the resin material filled into the mold. The injection unit 1 and the mold clamping device of the first embodiment are arranged in a horizontal direction (X direction).

[0032] Figure 1 This is a diagram illustrating the structure of the injection device 1 according to the first embodiment. Figure 1 As shown, the injection device 1 includes a barrel holding section 10 (barrel 11), a nozzle 12, a resin material inlet 13, a material flow path 14, a flow path valve 15, and a material supply section 16. Furthermore, in Figure 1 The diagram shows only the structure of the injection device 1, omitting the illustrations of the base and the mold clamping device.

[0033] The barrel holding part 10 is a housing with a barrel 11 inside. The barrel 11 is a space for filling resin material. A plunger 17 (described later) is inserted inside the barrel 11.

[0034] A nozzle (injection port) 12 is provided at the front end (X2 side) of the barrel holding part 10. The nozzle 12 is the part used to inject resin material into the barrel 11 and communicates with the barrel 11. The front end of the nozzle 12 is connected to the sprue hole (not shown) of the mold clamping device.

[0035] Additionally, a resin material inlet (hereinafter also referred to as "inlet") 13 is provided on the front side of the barrel holding section 10. Inlet 13 is an opening for allowing resin material to flow into the barrel 11. Inlet 13 is connected to the barrel 11 via a flow path valve 15 (described later). One end of a material flow path 14 is connected to inlet 13. Material flow path 14 is a flow path that connects the material supply section 16 and the barrel 11. The other end of material flow path 14 is connected to the material supply section 16.

[0036] The flow path valve 15 is an electrically operated valve installed inside the barrel 11. The flow path valve 15 is, for example, an electrically operated three-way valve. When the flow path valve 15 is open, the material flow path 14 is connected to the barrel 11, allowing resin material to be supplied from the material flow path 14 to the barrel 11 via the inlet 13. Conversely, when the flow path valve 15 is closed, the material flow path 14 is not connected to the barrel 11, allowing resin material to be injected from the nozzle 12. The opening and closing of the flow path valve 15 is controlled by a control unit. Furthermore, the flow path valve 15 is not limited to a three-way valve; for example, it can be composed of one or two two-way valves. That is, the flow path valve 15 can be of any structure as long as it can control the connection / disconnection between the material flow path 14 and the barrel 11.

[0037] The material supply unit 16 is a device for supplying resin material (e.g., silicone resin) to the barrel 11. The resin material is supplied from the material supply unit 16 to the barrel 11 via the material flow path 14 and the inlet 13. The material supply unit 16 generates supply pressure by means of hydraulic pressure, a servo motor, or the like to supply the resin material to the barrel 11. The supply and stopping of the resin material in the material supply unit 16 are controlled by the control unit 25. Furthermore, the supply pressure refers to the pressure required by the material supply unit 16 to supply the resin material to the barrel 11. Specifically, the supply pressure is the sum of the material pressure (barrel internal pressure) and the pressure loss generated between the material supply unit 16 and the barrel 11.

[0038] In addition, the injection device 1 includes a plunger 17, a push member 18, a linear guide rail 19, a drive unit 20, a drive force transmission unit 21, and a control unit 25.

[0039] The plunger 17 is a rod-shaped member that can move forward and backward along the axial direction (X direction) of the barrel 11 inside the barrel 11. The portion of the plunger 17, except for its rear (X1 side) end, is inserted into the barrel 11. By advancing the plunger 17 while the barrel 11 is filled with resin material, the resin material filled into the barrel 11 is injected from the nozzle 12. In the injection apparatus 1 of the first embodiment, the rear (X1 side) end of the plunger 17 is always exposed outside the barrel 11. Therefore, it has the advantage that the operator can easily confirm the position of the rear end of the plunger 17 during injection processes, etc.

[0040] The pusher member 18 is a member that pushes the plunger 17 toward the nozzle 12 of the barrel 11. The pusher member 18 has an internal thread (not shown) formed on the inner circumferential surface of a hole extending in the thickness direction (X direction). The internal thread of the pusher member 18 engages with the ball screw 22 (external thread) of the drive force transmission unit 21. In the injection device 1 of the first embodiment, the plunger 17 and the pusher member 18 are not connected (hereinafter also referred to as "not connected"). Therefore, the pusher member 18 abuts against the plunger 17 when advancing and separates from the plunger 17 when retracting. The pusher member 18 is configured to be movable in the front-rear direction (X direction) along the linear guide 19. Furthermore, in the first and second embodiments (described later), the positions (P1 to P3) of the pusher member 18 are described with reference to the center in the thickness direction (X direction) of the pusher member 18.

[0041] The drive unit 20 is a device that generates a driving force to inject resin material filled into the barrel 11 through the nozzle 12. In this embodiment, the drive unit 20 is composed of a servo motor (including a servo amplifier, etc.). The driving force generated by the drive unit 20 is transmitted to the push member 18 via the drive force transmission unit 21 (described later). The push member 18 is retracted in the X1 direction or advanced in the X2 direction by the driving force generated by the drive unit 20.

[0042] In addition to being able to switch to a state where it generates its own driving force, the drive unit 20 can also be switched to a state where it rotates freely under external force. When the drive unit 20 is switched to the state where it rotates freely under external force, the drive unit 20 rotates according to the external force transmitted via the ball screw 22. In this case, the rotational speed of the servo motor is detected by a pulse encoder (not shown) and input to the control unit 25 (described later). Therefore, the control unit 25 can detect the position of the push member 18 based on the rotational speed of the servo motor not only when the drive unit 20 is actively driven, but also when the drive unit 20 is passively rotated by external force.

[0043] The drive unit 20, which consists of a servo motor, also supplies current to generate torque to maintain the push member 18 at a predetermined position P1 (described later). On the other hand, if the position of the push member 18 changes due to an external force, the drive unit 20 supplies current to generate torque to correct the amount of change, causing the servo motor to generate torque opposite to the external force, thereby maintaining the position of the push member 18. These operations in the drive unit 20 are controlled by the control unit 25.

[0044] The drive force transmission unit 21 is a device for transmitting the driving force of the drive unit 20 to the push member 18. The drive force transmission unit 21 includes a ball screw 22, a gear mechanism (not shown), etc. The ball screw 22 is a rod-shaped member that rotates under the driving force of the drive unit 20, and has an external thread (not shown) formed on its outer peripheral surface. In this embodiment, the drive force transmission unit 21 is composed of a single-axis ball screw 22.

[0045] The external thread of the ball screw 22 engages with the internal thread (not shown) of the push-in member 18. The gear mechanism is a device that transmits the driving force of the drive unit 20 to the ball screw 22. When the ball screw 22 rotates forward (forward rotation) under the driving force of the drive unit 20, the push-in member 18 retracts, for example (moves in the X1 direction). On the other hand, when the ball screw 22 rotates in reverse (reverse rotation), the push-in member 18 advances (moves in the X2 direction).

[0046] In the drive force transmission unit 21, the ball screw 22 can be switched to a state where it rotates under the driving force of the drive unit 20, or it can be switched to a state where it rotates freely under external force. When the ball screw 22 is switched to the state where it rotates freely, it rotates according to the external force applied from the push member 18. The rotation of the ball screw 22 is transmitted to the drive unit 20 via a gear mechanism. The switching of the drive force transmission unit 21 is controlled by the control unit 25.

[0047] The control unit 25 is electrically connected to the flow valve 15, the material supply unit 16, the drive unit 20, and the drive force transmission unit 21 (gear mechanism), and is a device for controlling the operation of these units. The control unit 25 is, for example, composed of a microprocessor unit including a CPU (central processing unit), memory, etc. Based on an application program for controlling the operation of the injection unit 1 (e.g., the metering control program described later), the control unit 25 controls the operation of each piece of hardware to execute a molding cycle consisting of an injection process, a holding pressure process, and a metering process. Hereinafter, the position control of the pusher member 18, performed by the control unit 25 in the injection and holding pressure processes, will be described.

[0048] During the injection of resin material, the control unit 25 performs the injection process and the holding pressure process. The control unit 25 performs speed control during the injection process and pressure control during the holding pressure process. Figure 1 As shown, during the injection process, the control unit 25 moves the pusher 18 from a predetermined position P1 (described later) to a switching position P2 (described later). When the pusher 18 moves forward, the plunger 17 pushed by the pusher 18 also moves forward. At this time, the control unit 25 controls the drive unit 20 to make the plunger 17 pushed by the pusher 18 move forward at a uniform speed (speed control).

[0049] When the push-in component 18 reaches the designated position, the control unit 25 switches from speed control to pressure control (pressure holding process). In this specification and accompanying drawings, the designated position from speed control to pressure control will be described as "switching position P2". Figure 1 The diagram shows the state where the pusher member 18 has advanced from the predetermined position P1 to the switching position P2. When the pusher member 18 advances to the switching position P2, the control unit 25 controls the drive unit 20 to apply a constant pressure (pressure control) to the resin material injected into the mold. During this pressure control, the pusher member 18 advances to the filling completion position P3. Generally, the switching position P2 ≠ the filling completion position P3. By performing the above-described pressure control for a predetermined time, the injection of the resin material is completed.

[0050] After the resin material injection is completed, the control unit 25 performs a metering process. At the start of the metering process, the control unit 25 controls the drive unit 20 to retract the pusher member 18 to a predetermined position P1. Alternatively, the control unit 25 may start the metering process at the moment the pusher member 18 begins to retract, and supply resin material to the barrel 11. As described above, since the plunger 17 is not connected to the pusher member 18, even if the pusher member 18 retracts, the plunger 17 hardly retracts. Furthermore, "predetermined position P1" indicates the position where the amount of resin material filled into the barrel 11 is the predetermined injection amount determined in one molding cycle. That is, by supplying resin material to the barrel 11 and retracting the plunger 17, when the plunger 17 abuts against the pusher member 18 and thus the drive unit 20 is under load, at least the predetermined injection amount of resin material determined in one molding cycle is filled into the barrel 11.

[0051] Furthermore, the position P1 can be calculated based on the stop position (origin position) of the push member 18, the rotational speed of the ball screw 22, and the pitch of the ball screw 22. As described above, the rotational speed of the ball screw (the rotational speed of the servo motor) is detected by the pulse encoder and output to the control unit 25. Therefore, the control unit 25 can detect the position of the push member 18 that is moving based on its position before movement and the actual rotational speed of the servo motor.

[0052] When the pusher member 18 retracts to the predetermined position P1, the control unit 25 opens the flow path valve 15 and controls the material supply unit 16 to supply resin material to the barrel 11. Thus, resin material is supplied from the material supply unit 16 to the barrel 11, initiating the metering of the resin material. When the resin material is supplied to the barrel 11, the plunger 17 retracts in the X1 direction due to the material pressure of the resin material and comes into contact with the pusher member 18, which has retracted to the predetermined position P1. After the plunger 17 contacts the pusher member 18, resin material continues to be supplied to the barrel 11, so the material pressure of the resin material acts on the drive unit 20 via the plunger 17, the pusher member 18, and the ball screw 22 (drive force transmission unit 21).

[0053] The control unit 25 increases or decreases the current flowing in the servo motor to obtain the torque required to maintain the position of the push-in member 18 against the external force received from the ball screw 22. The control unit 25 determines whether the load on the drive unit 20 has reached a predetermined value based on the increased or decreased current value. When the load on the drive unit 20 reaches the predetermined value due to the material pressure of the resin material, the control unit 25 closes the flow path valve 15 and stops the supply of resin material from the material supply unit 16 to the barrel 11. Thus, the metering of resin material to the barrel 11 is completed.

[0054] In the metering process, if the load on the drive unit 20 deviates from the allowable range, the control unit 25 performs the following control: changes the stop position of the push member 18 from the predetermined position P1 so that the load on the drive unit 20 converges within the allowable range.

[0055] When the specified position is changed, the control unit 25 performs control to change the switching position P2 when transferring from the injection process to the pressure holding process. Here, in the control unit 25, the switching position P2 can be changed by the same amount as the correction amount of the specified position P1, or the correction amount can be calculated based on the correction amount and correction coefficient of the specified position P1, and the switching position P2 can be changed by the calculated value.

[0056] The control unit 25 performs control over the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11 during the metering process based on the calibration amount at the specified position P1.

[0057] The control performed by the control unit 25 in the metering process will be explained in detail later.

[0058] Next, the molding cycle (metering process, injection process, and pressure holding process) performed in the injection apparatus 1 of the first embodiment will be described.

[0059] In the actual molding cycle, the operation proceeds in the order of metering, injection, and holding pressure. However, here, we will first explain the injection and holding pressure processes. Figure 2A and Figure 2B This is a diagram illustrating the injection and pressure holding processes of the first embodiment.

[0060] Figure 2A This shows the state of the component 18 being pushed forward during the injection process. Before starting the injection process, resin material is first filled into the barrel 11. Resin material is then filled into the barrel 11 during the metering process described later. During the injection process, the control unit 25 closes the flow path valve 15 and controls the drive unit 20 (speed control) to cause the ball screw 22 (drive force transmission unit 21) to rotate in the reverse direction. Thus, as... Figure 2A As shown, the pusher 18 advances together with the plunger 17. As the plunger 17 advances, the resin material filled in the barrel 11 is injected from the nozzle 12 toward the mold.

[0061] Figure 2B The diagram shows the state where the injection process transitions to the holding pressure process, and the pusher member 18 has advanced to the switching position P2. After the injection process is completed by advancing the pusher member 18 to the switching position P2, the control unit 25 further advances the pusher member 18 to the filling completion position P3 to perform pressure control. By performing this pressure control for a predetermined time, the filling of the resin material is completed.

[0062] Next, the measurement process will be explained. Figures 3A-3C This is a diagram illustrating the metering process of the injection device 1 according to the first embodiment.

[0063] Figure 3A This shows the state after component 18 has been pushed in and retracted to the designated position P1 during the metering process. This is after the resin material filling is complete, as... Figure 3A As shown, the control unit 25 controls the drive unit 20 to retract the push member 18 to a predetermined position P1. Furthermore, since the plunger 17 is not connected to the push member 18, the plunger 17 hardly retracts even when the push member 18 retracts.

[0064] Figure 3B This illustrates the state in which the plunger 17 retracts due to the material pressure of the resin material during the metering process. After the pusher member 18 retracts to the predetermined position P1, the control unit 25 opens the flow path valve 15 and controls the material supply unit 16 to supply resin material to the barrel 11. Thus, resin material is supplied from the material supply unit 16 to the barrel 11, initiating the metering of the resin material. When the resin material is supplied to the barrel 11, as... Figure 3B As shown, the plunger 17 retracts due to the material pressure of the resin material.

[0065] Figure 3CThis illustrates the state in which the plunger 17 abuts against the pusher member 18 during the metering process. As described above, when resin material is supplied from the material supply section 16 to the barrel 11, the plunger 17 retracts due to the material pressure of the resin material, and as... Figure 3C As shown, the plunger 17 abuts against the pusher member 18, which has retracted to the designated position P1. After the plunger 17 abuts against the pusher member 18, resin material continues to be supplied to the barrel 11, so the material pressure of the resin material acts on the drive unit 20 via the ball screw 22. When the load on the drive unit 20 due to the material pressure of the resin material reaches a designated value, the control unit 25 closes the flow path valve 15 and stops the supply of resin material from the material supply unit 16 to the barrel 11. Thus, the metering of resin material to the barrel 11 is completed.

[0066] Next, the other controls performed in the above-mentioned metering process will be explained.

[0067] (Adjustment of material pressure for resin materials)

[0068] Figure 4 This diagram illustrates the control of adjusting the material pressure of the resin material. When the flow path valve 15 is closed during metering to stop supplying resin material to the barrel 11, and the load on the drive unit 20 deviates from the allowable range, the possibility of excessive or insufficient internal pressure in the barrel 11 is considered. In such cases, when the load on the drive unit 20 deviates from the allowable range, it is difficult to maintain a constant material pressure of the resin material within the barrel 11. Therefore, in this embodiment, when the flow path valve 15 is closed during metering to stop supplying resin material to the barrel 11, and the load on the drive unit 20 deviates from the allowable range, the control unit 25 performs control to retract or advance the stop position of the metering push member 18 from the predetermined position P1.

[0069] Specifically, if the load on the drive unit 20 exceeds the upper limit of the allowable range after the flow path valve 15 is closed during metering to stop the supply of resin material to the barrel 11, such as... Figure 4 As shown, the stopping position of the pusher 18 is changed to a position P1+a on the X1 side compared to the predetermined position P1. This reduces the material pressure of the resin material filling the barrel 11. On the other hand, if the load on the drive unit 20 is less than the lower limit of the allowable range after the flow path valve 15 is closed during metering to stop the supply of resin material to the barrel 11, such as... Figure 4 As shown, the stopping position of the pusher 18 is changed to a position P1-b on the X2 side compared to the predetermined position P1. This increases the material pressure of the resin material filling the barrel 11.

[0070] The stop position of the push-in member 18 can be changed either in stages based on a preset correction amount or continuously. If the load on the drive unit 20 deviates from the allowable range during metering, the control unit 25 performs the aforementioned control until the load on the drive unit 20 converges within the allowable range, thus maintaining a constant material pressure of the resin material in each molding cycle. Furthermore, when the stop position of the push-in member 18 is changed, the control unit 25 stores the correction amount in a memory (not shown), and adjusts the stop position of the push-in member 18 based on the stored correction amount in the next molding cycle.

[0071] (Change of location)

[0072] Figure 5 This diagram illustrates the control of changing the switching position. When the stop position of the pusher 18 is changed during the metering process, in order to maintain a constant injection volume of resin material, it is desirable to change the switching position P2, which transitions from speed control to pressure control. Therefore, when the stop position of the pusher 18 is changed during metering (refer to...), Figure 4 The control unit 25 performs control to change the switching position P2.

[0073] Specifically, during measurement, the stopping position of the pushed-in component 18 is changed to a position P1+a on the X1 side compared to the specified position P1 (refer to...). Figure 4 In the case of ), such as Figure 5 As shown, the switching position P2 is changed to the position P2+a on the X1 side. On the other hand, during measurement, the stopping position of the push-in member 18 is changed to the position P1-b on the X2 side compared to the specified position P1 (see reference). Figure 4 In the case of ), such as Figure 5 As shown, the switching position P2 is changed to the position P2-b on the X2 side. By performing such control in the control unit 25, the injection amount of resin material can be kept constant in the injection process of each molding cycle.

[0074] In this embodiment, if the stop position of the push-in member 18 is changed, such as Figure 5As shown, the correction amount for switching position P2 is set to the same amount (+a or -b) as the change in the stop position of the push-in member 18, thus enabling a more rapid change in switching position P2. Alternatively, as another embodiment, switching position P2 can be changed based on the value obtained by multiplying the change in the stop position of the push-in member 18 (+a or -b) by a pre-set correction coefficient β. For example, if the changed stop position of the push-in member 18 is P1+α, and the correction coefficient β is 0.8, then the correction amount for switching position P2 is +α×0.8. According to this control, the correction coefficient is changed based on the amount of resin material injected in each molding cycle, thereby enabling more precise adjustment of switching position P2. Furthermore, in this control, the correction coefficient β can also be changed based on the direction of movement of switching position P2.

[0075] Furthermore, when the injection device 1 is applied to a sealing coating device or the like that does not require a pressure holding process, the change in the switching position from speed control to pressure control is controlled as a change in the injection completion position.

[0076] (Changes in the supply pressure of the resin material)

[0077] When it is necessary to move the stop position of the pusher 18 backward or forward from the predetermined position P1 during metering, the possibility that the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11 may be too high or too low is also considered. Therefore, in this embodiment, when the stop position of the pusher 18 during metering is changed from the predetermined position P1, the control unit 25 performs control to change the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11.

[0078] Specifically, if the stop position of the pusher member 18 is moved back from the predetermined position P1 during metering, the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11 is reduced in the next molding cycle. On the other hand, if the stop position of the pusher member 18 is moved forward from the predetermined position P1 during metering, the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11 is increased in the next molding cycle. By performing such control, the material pressure of the resin material in each molding cycle can be kept constant.

[0079] Furthermore, the control of adjusting the material pressure of the resin material, changing the switching position, and changing the supply pressure of the resin material described above can also be applied in the injection device 1A of the second embodiment described later.

[0080] Next, based on Figure 6A and Figure 6BThe flowchart shown illustrates the processing content of the metering control program executed by the control unit 25 in the first embodiment. Figure 6A and Figure 6B This is a flowchart illustrating the processing procedure of the metering control program executed by the control unit 25 in the first embodiment.

[0081] exist Figure 6A In step S101 shown, the control unit 25 (refer to...) Figure 1 The control drive unit 20 is used to retract the push-in member 18 to the specified position P1.

[0082] In step S102, the control unit 25 opens the flow path valve 15 and controls the material supply unit 16 to supply resin material to the barrel 11. Thus, resin material is supplied from the material supply unit 16 to the barrel 11, initiating resin material metering. When the resin material is supplied to the barrel 11, the plunger 17 retracts due to the material pressure of the resin material (see reference). Figure 3B ).

[0083] In step S103, the control unit 25 determines whether the load received by the drive unit 20 has reached a predetermined value. If the control unit 25 determines in step S103 that the load received by the drive unit 20 has reached the predetermined value, the process proceeds to step S104. On the other hand, if the control unit 25 determines in step S103 that the load received by the drive unit 20 has not reached the predetermined value, the process proceeds to step S103 (return).

[0084] In step S104 (step S103: "Yes"), the control unit 25 closes the flow path valve 15 and stops the supply of resin material from the material supply unit 16 to the barrel 11. Thus, the metering of resin material to the barrel 11 is completed.

[0085] In step S105, the control unit 25 determines whether the load received by the drive unit 20 is within the allowable range. If the control unit 25 determines in step S105 that the load received by the drive unit 20 is within the allowable range, the process proceeds to step S107. Figure 6B On the other hand, if the control unit 25 determines in step S105 that the load received by the drive unit 20 is outside the allowable range, the process is transferred to step S106.

[0086] In step S106 (step S105: "No"), the control unit 25 moves the stop position of the push member 18 backward or forward from the predetermined position P1. The control unit 25 executes the control of step S106 until it is determined in step S105 that the load on the drive unit 20 is within the allowable range.

[0087] exist Figure 6BIn step S107 (step S105: "Yes"), the control unit 25 determines whether there is any change in the stop position of the push-in member 18. If the control unit 25 determines in step S107 that there is no change in the stop position of the push-in member 18, the processing of this flowchart ends. On the other hand, if the control unit 25 determines in step S107 that there is a change in the stop position of the push-in member 18, the processing proceeds to step S108.

[0088] In step S108 (step S107: "No"), the control unit 25 changes the switching position P2 based on the changed stop position of the push member 18. Additionally, the control unit 25 changes the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11 based on the changed stop position of the push member 18. After the processing in step S108 is completed, the processing of this flowchart ends.

[0089] The injection device 1 according to the first embodiment described above, for example, has the following effects.

[0090] In the injection apparatus 1 of the first embodiment, the control unit 25 performs the following control: the plunger 17 is retracted by the material pressure of the resin material, and the metering of the resin material is completed when the load on the drive unit 20 due to the material pressure of the resin material reaches a predetermined value. Therefore, compared with the method of forcibly retracting the plunger by the plunger drive device, the entry of air into the barrel 11 can be suppressed. In particular, in the case of low-viscosity liquid resin materials such as silicone, the entry of air into the barrel 11 can be suppressed more effectively. In addition, it is not necessary to control the position of the plunger while measuring the material pressure in the barrel 11 using a pressure sensor, so not only is a pressure sensor not needed, but also a connecting member for connecting the plunger to the plunger drive device is not needed. Therefore, according to the injection apparatus 1 of the first embodiment, a constant amount of resin material can be injected for each injection step while suppressing the entry of air into the barrel 11 and reducing the cost due to the increase in the number of parts.

[0091] In the injection apparatus 1 of the first embodiment, when the load on the drive unit 20 deviates from the allowable range, the control unit 25 performs the following control: it moves the stop position of the push member 18 backward or forward from the predetermined position P1, so that the load on the drive unit 20 converges within the allowable range. According to this control, the material pressure of the resin material filling the barrel 11 is adjusted according to the amount by which the load on the drive unit 20 deviates from the allowable range, thus enabling the material pressure of the resin material in each molding cycle to be kept constant.

[0092] In the injection apparatus 1 of the first embodiment, when the control unit 25 performs control to move the stop position of the push member 18 backward or forward from the predetermined position P1, it performs control to change the switching position P2 from speed control to pressure control, so that the amount of resin material injected can be kept constant in the injection process of each molding cycle.

[0093] In the above control, by setting the correction amount for the switching position P2 as the same amount as the change in the stop position of the push-in member 18, the change in the switching position P2 can be performed more quickly. Alternatively, in the above control, the switching position P2 can also be changed based on the value obtained by multiplying the change in the stop position of the push-in member 18 by a pre-set correction coefficient β. In this case, the correction coefficient β is changed according to the amount of resin material injected in each molding cycle, thereby allowing for more precise adjustment of the switching position P2.

[0094] In the injection apparatus 1 of the first embodiment, when the stop position of the metering push member 18 is changed from the predetermined position P1, the control unit 25 performs control to change the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11, so that the material pressure of the resin material in each molding cycle can be kept constant.

[0095] (Second Implementation)

[0096] The difference between the injection device 1A of the second embodiment and the first embodiment is that, in the second embodiment, the plunger 17 is connected to the pusher member 18. In the second embodiment, the other structures are the same as in the first embodiment. Therefore, in the description and drawings of the second embodiment, components equivalent to those in the first embodiment are labeled with the same reference numerals as in the first embodiment, and repeated descriptions are omitted. The basic structure of the injection device 1A of the second embodiment is... Figure 1 The same. Furthermore, in the injection apparatus 1A of the second embodiment, the injection step and the pressure holding step of the molding cycle (see...) Figure 2A and Figure 2B The process is the same as in the first embodiment, so only the metering process will be described.

[0097] Figure 7A and Figure 7B This is a diagram illustrating the metering process of the injection device 1A according to the second embodiment.

[0098] Figure 7A This shows the state immediately following the start of the metering process. After the resin material injection is completed, while maintaining the positions of the plunger 17 and the pusher 18, the control unit 25 switches the drive unit 20 and the ball screw 22 to a state where they can rotate freely by external force.

[0099] Next, the control unit 25 opens the flow path valve 15 and controls the material supply unit 16 to supply resin material to the barrel 11. Thus, resin material is supplied from the material supply unit 16 to the barrel 11, initiating the metering of the resin material. When the resin material is supplied to the barrel 11, as... Figure 7A As shown, the plunger 17 and the push member 18 retract under the pressure of the resin material. At this time, the drive unit 20 and the ball screw 22 rotate along with the retraction of the plunger 17 and the push member 18. Furthermore, in the following description, the plunger 17 and the push member 18 will also be collectively referred to as "push member 18".

[0100] Figure 7B This shows the state in which the push-in member 18 and the plunger 17 retract together to the specified position during the metering process. It is then determined whether the push-in member 18 has... Figure 7B As shown, the material pressure of the resin material causes the ball screw to retract to the designated position P1. As described above, the rotational speed of the ball screw is detected by a pulse encoder (not shown) as the rotational speed of the servo motor. Therefore, the control unit 25 can detect the position of the push member 18 after movement based on the position of the push member 18 before movement and the actual rotational speed of the servo motor.

[0101] When the pusher 18 retracts to the predetermined position P1, the control unit 25 releases the drive unit 20 and the ball screw 22 from the state of free rotation by external force. Then, the control unit 25 supplies current to the drive unit 20 to maintain the position of the pusher 18, thereby keeping the pusher 18 at the predetermined position P1. After the pusher 18 retracts to the predetermined position P1, resin material continues to be supplied to the barrel 11, so the material pressure of the resin material acts on the drive unit 20 via the ball screw 22. When the load on the drive unit 20 due to the material pressure of the resin material reaches a predetermined value, the control unit 25 closes the flow path valve 15 and stops the supply of resin material from the material supply unit 16 to the barrel 11. Thus, the metering of resin material to the barrel 11 is completed.

[0102] Next, based on Figure 8A and Figure 8B The flowchart shown illustrates the processing content of the metering control program executed by the control unit 25 in the second embodiment. Figure 8A and Figure 8B This is a flowchart illustrating the processing procedure of the metering control program executed by the control unit 25 in the second embodiment.

[0103] exist Figure 8A In step S201 shown, the control unit 25 (refer to) Figure 1 The drive unit 20 and the ball screw 22 are switched to a state where they can rotate freely by external force.

[0104] In step S202, the control unit 25 opens the flow path valve 15 and controls the material supply unit 16 to supply resin material to the barrel 11. Thus, resin material is supplied from the material supply unit 16 to the barrel 11, initiating the metering of the resin material. When the resin material is supplied to the barrel 11, the pusher member 18 retracts due to the material pressure of the resin material (see reference). Figure 7A ).

[0105] In step S203, the control unit 25 determines whether the pushing member 18 has retracted to the predetermined position P1. If the control unit 25 determines in step S203 that the pushing member 18 has retracted to the predetermined position P1, the process proceeds to step S204. On the other hand, if the control unit 25 determines in step S203 that the pushing member 18 has not retracted to the predetermined position P1, the process proceeds to step S203 (return).

[0106] In step S204 (step S203: "Yes"), the control unit 25 releases the drive unit 20 and the ball screw 22 from the state of being freely rotated by external force.

[0107] In step S205, the control unit 25 determines whether the load on the drive unit 20 has reached a predetermined value. If the control unit 25 determines in step S205 that the load on the drive unit 20 has reached the predetermined value, the process proceeds to step S206. Figure 8B On the other hand, if the control unit 25 determines in step S205 that the load received by the drive unit 20 has not reached the allowable value, the process is transferred to step S205 (return).

[0108] exist Figure 8B In step S206 (step S205: "Yes"), the control unit 25 closes the flow path valve 15 and stops the supply of resin material from the material supply unit 16 to the barrel 11. Thus, the metering of resin material to the barrel 11 is completed.

[0109] In step S207, the control unit 25 determines whether the load received by the drive unit 20 is within the allowable range. If the control unit 25 determines in step S207 that the load received by the drive unit 20 is within the allowable range, the process proceeds to step S209. On the other hand, if the control unit 25 determines in step S207 that the load received by the drive unit 20 is outside the allowable range, the process proceeds to step S208.

[0110] In step S208 (step S207: "No"), the control unit 25 moves the stop position of the push-in member 18 backward or forward from the predetermined position P1.

[0111] In step S209 (step S207: "Yes"), the control unit 25 determines whether there is no change in the stop position of the pushing member 18. If it is determined by the control unit 25 in step S209 that there is no change in the stop position of the pushing member 18, the processing of this flowchart ends. On the other hand, if it is determined by the control unit 25 in step S209 that there is a change in the stop position of the pushing member 18, the processing transfers to step S210.

[0112] In step S210 (step S209: "No"), the control unit 25 changes the switching position P2 based on the changed stop position of the pushing member 18. In addition, the control unit 25 changes the supply pressure of the resin material supplied from the material supply unit 16 to the barrel 11 based on the changed stop position of the pushing member 18. After the processing in step S210 ends, the processing of this flowchart ends.

[0113] In the injection device 1A of the second embodiment described above, the same effects as those of the injection device 1 of the first embodiment can also be obtained.

[0114] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and can be variously deformed and changed as in the following modification methods, and these are also included in the technical scope of the present invention. In addition, the effects described in the embodiments are merely the best effects produced by the present invention, and the effects of the present invention are not limited to the effects described in the embodiments. The above embodiments and the following modification methods can also be used in appropriate combination, but detailed descriptions are omitted. In addition, in the following description, the first embodiment and the second embodiment are also collectively referred to as "embodiments".

[0115] (Modification method)

[0116] In the embodiment, regarding the control for adjusting the material pressure of the resin material, the control for changing the switching position P2, and the control for changing the supply pressure of the resin material, it is not necessary to execute all of them. One or more controls can also be combined and executed, or it can be set to a mode in which these controls are not executed. In addition, in the embodiment, in the injection device, a structure in which the control unit 25 executes the control of starting / supplying the resin material (hereinafter, also referred to as "material supply control"), the control of the drive unit 20, the opening and closing of the flow path valve 15, and the control of the driving force transmission unit 21 (hereinafter, also referred to as "drive control") has been described, but it is not limited to this. In the injection device, the material supply control and the drive control can also be executed by different control units. In this case, for example, the timing of the material supply control can be synchronized with the timing of the drive control by outputting a control signal from the control unit that executes the drive control to the control unit that executes the material supply control.

[0117] In this embodiment, the plunger 17 retracts due to the material pressure of the resin material supplied to the barrel 11. Therefore, when the diameter of the plunger 17 is large enough, it is necessary to shorten the plunger 17. Figure 9 This is a diagram illustrating the structure of the injection device 1, which describes the deformation method. (For example...) Figure 9 As shown, when the diameter of the plunger 17 is large enough to exceed a certain diameter, the plunger 17 can be shortened, and the pushing member 18 can be formed by a plate-shaped first pushing member 18a and a cylindrical second pushing member 18b. Figure 9 In the push-in member 18 shown, the first push-in member 18a and the second push-in member 18b may be either not connected or connected. In addition, the plunger 17 and the push-in member 18 may be either not connected as in the first embodiment or connected as in the second embodiment.

[0118] In the embodiment, a structure is described in which the driving force of the drive unit 20 is transmitted to the ball screw 22 via a gear mechanism in the drive force transmission unit 21. However, it is also possible to configure a structure in which the driving force of the drive unit 20 is transmitted to the ball screw 22 without passing through a gear mechanism.

[0119] In the embodiment, an example of the drive unit 20 being composed of a servo motor is described, but the drive unit 20 may also be composed of a hydraulic mechanism, for example.

[0120] In the embodiments, an example of applying the injection device to the injection molding machine 1 is described, but the injection device can also be applied to robots, etc., which have a dispenser that sprays resin material toward the object.

[0121] In the embodiment, an example of detecting the position of the push member 18 based on the rotational speed of the servo motor constituting the drive unit 20 is described. However, external sensors such as photoelectric sensors or cameras can also be used to detect the position of the push member 18.

[0122] In the embodiment, an example of a drive force transmission unit 21 consisting of a single-axis ball screw is described, but the drive force transmission unit 21 may also be consisting of a dual-axis ball screw, or even a ball screw consisting of three or more axes.

[0123] In the embodiments, an example of arranging the injection device and the mold clamping device in a horizontal direction is described, but it is also possible to arrange the injection device and the mold clamping device in a vertical direction.

[0124] Explanation of reference numerals in the attached figures

[0125] 1, 1A: Injection device; 10: Barrel holding part; 11: Barrel; 12: Nozzle; 13: Resin material inlet; 14: Material flow path; 15: Flow path valve; 16: Material supply part; 17: Plunger; 18: Pushing component; 19: Linear guide rail; 20: Drive part; 21: Drive force transmission part; 22: Ball screw; 25: Control part.

Claims

1. An injection device for injecting resin material through an injection port disposed at the front end of a barrel, the injection device comprising: A resin material inlet is provided for allowing resin material to flow into the feed cylinder; A drive unit that generates a driving force to inject resin material filled into the barrel from the injection port; A plunger is provided in a manner that allows it to move forward and backward along the axial direction of the barrel. The plunger moves backward as resin material flows into the barrel from the resin material inlet and moves forward within the barrel to inject the resin material filled in the barrel toward the injection port. A pusher component that pushes the plunger toward the injection port of the barrel; A driving force transmission unit, which is used to transmit the driving force generated by the driving unit to the pushing member; as well as The control unit controls each part to cause the resin material to begin flowing into the barrel from the resin material inlet. When the load on the drive unit from the push member located at a predetermined position reaches a predetermined value, the metering of the resin material is completed. If the load on the drive unit deviates from the allowable range, the control unit changes the stop position of the push member from the predetermined position to bring the load back within the allowable range.

2. The injection device according to claim 1, wherein, The push-in component is not connected to the plunger. The control unit controls each part to cause the resin material to begin flowing into the barrel from the resin material inlet. When the pushing member retracts to a predetermined position through the drive unit and the load on the drive unit reaches a predetermined value, the metering of the resin material is completed.

3. The injection device according to claim 1, wherein, The push-in member is connected to the plunger. The control unit controls each part to cause the resin material to begin flowing from the resin material inlet into the barrel. When the pushing member retracts to a predetermined position after passing the plunger and the load on the driving unit reaches a predetermined value, the metering of the resin material is completed.

4. The injection device according to claim 3, wherein, When the stop position of the push-in member is changed, the control unit changes the injection completion position or the switching position when transferring from the injection process to the pressure holding process.

5. The injection device according to claim 4, wherein, The control unit changes the injection completion position or the switching position by the same amount as it changes the stop position of the push-in member from the predetermined position.

6. The injection device according to claim 4, wherein, The control unit calculates the correction amount for the injection completion position or the switching position based on the amount by which the stopping position of the push-in member is changed from the predetermined position and a correction coefficient.

7. The injection device according to any one of claims 3 to 6, wherein, It also includes a resin material supply unit that supplies resin material to the barrel. The control unit adjusts the supply pressure of the resin material supplied from the resin material supply unit to the barrel in the next metering process based on the calibration amount at the specified position.

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