Injection molding machine and temperature control method thereof

Abstract

To prevent or suppress lowering of dimensional accuracy of a molding to be injected.SOLUTION: An injection molding machine includes: a nozzle adapter 50 for mounting an injection nozzle 40 to a heating cylinder 30; a resin flow path P1 communicating with the heating cylinder 30 and the injection nozzle 40; a heater 70 for an adapter provided in the periphery of the resin flow path P1; and a control part 100 for controlling output of the heater 70 for the adapter so as to suppress variation of a temperature of a molten resin passing through the resin flow path P1.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an injection molding machine and a method for controlling the temperature thereof. [Background technology]

[0002] Injection molding machines are known that mold resin components (resin molded products) into desired shapes. A typical injection molding machine is composed of an injection unit and a mold clamping unit. The injection unit melts a resin material and supplies the molten resin material (molten resin) to the mold clamping unit. More specifically, the injection unit injects (injects) the molten resin into the cavity of a mold.

[0003] The injection device has a heating cylinder that produces molten resin, an injection nozzle that injects the molten resin, and a nozzle adapter for attaching the injection nozzle to the heating cylinder. The molten resin produced by the heating cylinder flows through the nozzle adapter into the injection nozzle and is injected from the tip of the injection nozzle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6851703 Summary of the Invention [Problem to be solved by the invention]

[0005] If the temperature of the molten resin fluctuates while passing through the nozzle adapter, the temperature of the injected molded product may vary, which may reduce the dimensional accuracy of the molded product.

[0006] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0007] An injection molding machine according to one embodiment includes a nozzle adapter for attaching an injection nozzle to a heating cylinder, a resin flow path communicating with the heating cylinder and the injection nozzle, an adapter heater provided around the resin flow path, and a control unit that controls an output of the adapter heater so as to suppress fluctuations in temperature of molten resin passing through the resin flow path, A nozzle heater is arranged in the injection nozzle, and a cylinder heater is arranged in the heating cylinder, and the control unit operates the nozzle heater and the cylinder heater during the production of a molded product, and controls the output of the adapter heater according to the degree of deterioration in the dimensional accuracy of the molded product. . [Effects of the Invention]

[0008] According to one embodiment, a decrease in the dimensional accuracy of an injection molded product is prevented or suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an injection molding machine according to an embodiment. [Figure 2] FIG. 4 is a partial cross-sectional view showing a connection portion between a heating cylinder and an injection nozzle. [Figure 3] FIG. 2 is a cross-sectional view showing a nozzle adapter. [Figure 4] 10A to 10C are explanatory diagrams showing the assembly procedure of the nozzle adapter. [Figure 5] FIG. 10 is a partial cross-sectional view showing a modified example of the injection device. [Figure 6] 10A and 10B are diagrams illustrating another example of the configuration of the first heater for the adapter and an overview of temperature control. [Figure 7] 10 is a diagram showing the arrangement of heaters other than the first adapter heater. FIG. [Figure 8] 10 is a flowchart mainly showing a process for controlling the output of a first heater for an adapter. [Figure 9] 10A to 10C are diagrams illustrating an example of a process for measuring the dimensions of a molded product injected from the device. [Figure 10] 1A and 1B are diagrams illustrating an example of an injection molded product and an example of dimensional measurement. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment will be described in detail below with reference to the drawings. In all drawings used to explain the embodiment, the same reference numerals are used to designate components and devices having the same or substantially the same functions, and repeated description thereof will be omitted.

[0011] <Injection molding machine> FIG. 1 is a schematic diagram showing an injection molding machine according to this embodiment. The illustrated injection molding machine 1 is composed of a mold clamping unit 2 and an injection unit 3. Molds 11 and 12 are attached to the mold clamping unit 2. The mold clamping unit 2 opens and closes the attached molds 11 and 12. The injection unit 3 heats and melts the resin material. The injection unit 3 injects the melted resin material (molten resin) into the molds 11 and 12 attached to the mold clamping unit 2. More specifically, the injection unit 3 injects the molten resin into the cavities of the molds 11 and 12.

[0012] <Mold clamping device> The mold clamping unit 2 includes a fixed platen 14, a mold clamping housing 15, and a movable platen 16, which are provided on a common bed 13. The fixed platen 14 is fixed to the bed 13. On the other hand, the mold clamping housing 15 and the movable platen 16 are slidable on the bed 13.

[0013] The fixed platen 14 and the mold clamping housing 15 are connected by a plurality of tie bars 17. More specifically, the fixed platen 14 and the mold clamping housing 15 are connected by four tie bars 17. The movable platen 16 is slidable between the fixed platen 14 and the mold clamping housing 15 in the opposing directions.

[0014] A mold clamping mechanism 18 is provided between the mold clamping housing 15 and the movable platen 16. More specifically, a link-type mold clamping mechanism 18 is provided between the mold clamping housing 15 and the movable platen 16. From another perspective, a toggle mechanism is provided between the mold clamping housing 15 and the movable platen 16.

[0015] The mold clamping mechanism 18 moves the mold 11 attached to the movable platen 16 toward and away from the mold 12 attached to the fixed platen 14. When the mold 11 comes into contact with the mold 12, the molds 11 and 12 are closed. On the other hand, when the mold 11 moves away from the mold 12, the molds 11 and 12 are opened. While closing the molds 11 and 12, the mold clamping mechanism 18 can press the mold 11 against the mold 12 to prevent the molds 11 and 12 from opening. The mold clamping mechanism 18 can be replaced with a direct pressure type mold clamping mechanism (mold clamping cylinder).

[0016] <Injection device> The injection device 3 is provided on a base 20 adjacent to the bed 13. The injection device 3 is composed of a heating cylinder 30, an injection nozzle 40, a shut-off nozzle 90, etc. The injection device 3 is driven by a nozzle touch device 21 in a direction approaching the mold clamping device 2 (forward), and also in a direction away from the mold clamping device 2 (rearward). In other words, the injection device 3 moves forward and backward (rearward) relative to the mold clamping device 2. When the injection device 3 moves forward to a predetermined position, the tip of the injection nozzle 40 comes into contact with the sprue bushing of the mold 12.

[0017] A hopper 31 is provided on the rear end side of the heating cylinder 30. The hopper 31 is a supply port for supplying the resin material to the heating cylinder 30. The resin material is put into the hopper 31 and sent into the heating cylinder 30 through the hopper 31.

[0018] A screw 32 is provided inside the heating cylinder 30. The screw 32 is driven inside the heating cylinder 30 by a drive mechanism covered by a cover 33. From another perspective, the screw 32 performs rotational motion inside the heating cylinder 30. The screw 32 also performs linear motion inside the heating cylinder 30. The direction of the linear motion of the screw 32 is the same as the direction of movement of the injection unit 3 relative to the mold clamping unit 2. In other words, the screw 32 is driven linearly inside the heating cylinder 30 in a direction approaching the mold clamping unit 2 (forward) and a direction away from the mold clamping unit 2 (rearward).

[0019] The heating cylinder 30 heats and melts the supplied resin material. A heater for heating the heating cylinder 30 is provided around the heating cylinder 30. For example, one or more band heaters are wrapped around the heating cylinder 30. The resin material supplied to the heating cylinder 30 is heated and melted by the heat emitted from the heater and by shear heat generated by the rotation of the screw 32.

[0020] <Manufacturing method for resin molded products> Next, we will explain an example of a procedure (process) for manufacturing a resin molded product using the injection molding machine 1 shown in Figure 1. First, the molds 11 and 12 attached to the mold clamping unit 2 are opened, and the injection unit 3 is moved backward.

[0021] Thereafter, the resin material is charged into the hopper 31 of the injection device 3. For example, resin material processed into beads or pellets is charged into the hopper 31. However, the resin material may be charged into the hopper 31 in advance before the injection device 3 is moved backward.

[0022] The resin material fed into the hopper 31 is supplied to the heating cylinder 30. The resin material supplied to the heating cylinder 30 is heated and melted. The melted resin material (molten resin) is sent to the tip side of the heating cylinder 30 by the rotation of the screw 32. From another perspective, the molten resin fills the space between the screw 32 and the injection nozzle 40.

[0023] Thereafter, the injection device 3 is moved forward, and the tip of the injection nozzle 40 is brought into contact with the sprue bushing of the mold 12 (the molds 11 and 12 are closed beforehand). Next, the screw 32 is moved forward within the heating cylinder 30. At this time, the screw 32 is not rotated. Then, the molten resin is injected (injected) from the tip (injection port) of the injection nozzle 40 into the cavities of the molds 11 and 12.

[0024] The screw 32 continues to apply pressure (hold pressure) to the molten resin even after it has been injected into the cavity. The molds 11 and 12 are cooled while maintaining the state in which pressure is applied to the molten resin in the cavity.

[0025] While the molds 11 and 12 are cooling, the screw 32 is rotated again to prepare for the next injection. Specifically, the screw 32 is rotated to send molten resin to the tip side of the heating cylinder 30. In other words, the molten resin to be injected next is filled between the screw 32 and the injection nozzle 40. As a result, the screw 32 is moved backward by a reaction force. This process of moving the screw 32 backward while sending the molten resin forward is called "metering."

[0026] After the molds 11 and 12 have been cooled to a temperature below the solidification temperature of the molten resin in the cavity, the molds 11 and 12 are opened and the resin molded product is taken out.

[0027] By repeating the above process, resin molded products of the same shape can be continuously manufactured, that is, resin molded products of a desired shape can be mass-produced.

[0028] <Nozzle adapter> Next, the connection structure between the heating cylinder 30 and the injection nozzle 40 will be described. Figure 2 is a partial cross-sectional view showing the connection between the heating cylinder 30 and the injection nozzle 40. A nozzle adapter 50 is interposed between the heating cylinder 30 and the injection nozzle 40. The injection nozzle 40 is attached to the tip of the heating cylinder 30 via the nozzle adapter 50.

[0029] A resin flow path P1 is provided inside the nozzle adapter 50, passing through the nozzle adapter 50 in the axial direction and communicating with the heating cylinder 30 and the injection nozzle 40. A resin flow path P2 is provided inside the injection nozzle 40, passing through the injection nozzle 40 in the axial direction. One end of the resin flow path P2 inside the injection nozzle 40 communicates with the resin flow path P1 inside the nozzle adapter 50, The other end of the resin flow path P2 in the injection nozzle 40 is connected to the injection outlet 41 of the injection nozzle 40. As a result, a series of resin flow paths P is formed that extends from the heating cylinder 30 to the injection outlet 41 of the injection nozzle 40. In the following description, the resin flow path P1 in the nozzle adapter 50 may be referred to as the "adapter flow path P1," and the resin flow path P2 in the injection nozzle 40 may be referred to as the "nozzle flow path P2" to distinguish between them. The nozzle adapter 50 may also be abbreviated to "adapter 50."

[0030] FIG. 3 is a cross-sectional view showing the adapter 50. The adapter 50 has an adapter main body 51 and a flange portion 52. The adapter main body 51 includes a connection end portion 53 and an intermediate portion 54. The connection end portion 53 is provided at one axial end (rear end) of the adapter 50, and the flange portion 52 is provided at the other axial end (front end) of the adapter 50. The intermediate portion 54 is provided between the connection end portion 53 and the flange portion 52. That is, the connection end portion 53, the intermediate portion 54, and the flange portion 52 are arranged in this order along the axial direction. More specifically, the connection end portion 53, the intermediate portion 54, and the flange portion 52 are arranged in this order from the rear end side to the front end side of the adapter 50. From another perspective, the connection end portion 53, the intermediate portion 54, and the flange portion 52 are arranged in this order from the upstream side to the downstream side of the resin flow path P.

[0031] However, the adapter 50 is not a single member, but is composed of two separable, integrated members. In other words, the adapter 50 is a separable type. Specifically, the adapter 50 is composed of a metal member 51A that forms the adapter body 51 and a metal member 52B that forms the flange portion 52. The metal member 51A that forms the adapter body 51 is also the metal member that forms the connection end portion 53 and the intermediate portion 54.

[0032] One metal member 51A forming the adapter body 51 has a generally cylindrical shape, while the other metal member 52B forming the flange 52 has a generally annular shape. These two metal members 51A and 52B are integrated by screw connection.

[0033] <Adapter body> The adapter body 51 has a stepped shape in which the outer diameter changes stepwise along the axial direction. The part of the adapter body 51 with the largest outer diameter forms the connection end 53. The outer peripheral surface of the connection end 53 is formed with a screw that can be coupled with a screw formed on the inner peripheral surface of the heating cylinder 30.

[0034] The adapter 50 is fixed to the heating cylinder 30 by connecting a screw formed on the outer circumferential surface of the connecting end 53 to a screw formed on the inner circumferential surface of the heating cylinder 30 .

[0035] An intermediate portion 54 is formed by a portion of the adapter body 51 having an outer diameter smaller than that of the portion forming the connecting end portion 53 .

[0036] The connecting portion 56 is formed by a part of the adapter body 51 having an outer diameter smaller than that of the portion forming the intermediate portion 54. From another perspective, the connecting portion 56 is a convex portion provided on the tip surface of the adapter body 51. A thread is formed on the outer peripheral surface of the connecting portion 56 so that it can be coupled with a thread formed on the inner peripheral surface of the flange portion 52.

[0037] The adapter flow path P1 axially penetrates the adapter body 51. More specifically, the adapter flow path P1 penetrates the connection end portion 53, the intermediate portion 54, and the connecting portion 56. The intermediate portion 54 is provided with an insertion hole 55 that extends obliquely toward the adapter flow path P1.

[0038] <Flange> The outer diameter of flange 52 is larger than the outer diameter of connection end 53. The inner diameter of flange 52 is smaller than the outer diameter of intermediate portion 54 and larger than the outer diameter of connecting portion 56. Threads are formed on the inner peripheral surface of flange 52 so that they can be coupled with threads formed on the outer peripheral surface of connecting portion 56. The threads formed on the inner peripheral surface of flange 52 are coupled to the threads formed on the outer peripheral surface of connecting portion 56, thereby fixing flange 52 to adapter main body 51. In other words, adapter main body 51 and flange 52 are integrated to assemble adapter 50.

[0039] Flange portion 52 is thicker than the height (protrusion length) of connecting portion 56. Therefore, even if adapter body 51 and flange portion 52 are integrated as described above, connecting portion 56 does not protrude from flange portion 52.

[0040] <Groove> A groove 60 is provided around the periphery of the intermediate portion 54, extending in the circumferential direction of the intermediate portion 54. The groove 60 is provided around the entire circumference of the intermediate portion 54. From another perspective, a recess is provided on the outer circumferential surface of the adapter 50 around the entire circumference.

[0041] The groove 60 is formed by the connecting end portion 53, the flange portion 52, and the intermediate portion 54. Specifically, one inner side surface 61 of the groove 60 is formed by the end face 53a of the connecting end portion 53 facing the flange portion 52. The other inner side surface 62 of the groove 60 is formed by the end face 52b of the flange portion 52 facing the connecting end portion 53. Furthermore, the bottom surface 63 of the groove 60 is formed by the outer peripheral surface 54c of the intermediate portion 54.

[0042] From another perspective, inner surfaces 61, 62 of groove 60 are formed by the opposing front surface 53a of connection end 53 and the back surface 52b of flange 52. However, when adapter body 51 and flange 52 are integrated, part of back surface 52b of flange 52 faces front surface 54a of intermediate portion 54 and is in close contact with front surface 54a. In other words, inner surface 62 of groove 60 is formed by part (annular region) of back surface 52b of flange 52 that protrudes radially outward from front surface 54a of intermediate portion 54.

[0043] As described above, the middle portion 54 of the adapter body 51 is provided with an insertion hole 55 extending toward the adapter flow path P1. This insertion hole 55 extends obliquely from the outer peripheral surface 54c of the middle portion 54 toward the adapter flow path P1. In other words, the insertion hole 55 is drilled in the outer peripheral surface 54c of the middle portion 54 (the bottom surface 63 of the groove 60). The inclination angle of the insertion hole 55 with respect to the adapter flow path P1 can be changed as appropriate. However, the insertion hole 55 does not have to be inclined.

[0044] <Heaters, insulation materials> The adapter 50 has a heater 70 provided around the resin flow path P1. More specifically, the heater 70 is housed in a groove 60 provided around the middle portion 54. Furthermore, a heat insulating material 71 is arranged around the heater 70 to cover the heater 70. The total thickness of the heater 70 and the heat insulating material 71 is the same as or approximately the same as the depth of the groove 60. As a result, the outer peripheral surface of the heat insulating material 71 is flush or approximately flush with the outer peripheral surface of the connection end portion 53.

[0045] 4 is an explanatory diagram showing the assembly procedure for the adapter 50. The heater 70 is a cylindrical microheater having an inner diameter large enough to insert the middle portion 54 of the adapter body 51. The heat insulating material 71 is a cylindrical heat insulating plate having an inner diameter large enough to insert the heater 70. The heat insulating material 71 can be, for example, a rigid heat insulating plate made by molding laminated glass fiber sheets with a binder or resin.

[0046] When assembling the adapter 50, the middle portion 54 of the adapter body 51 is inserted into the heater 70. From another perspective, the heater 70 is placed over the middle portion 54 of the adapter body 51. Then, the heater 70 is covered with the insulating material 71. Next, the flange portion 52 is fixed to the adapter body 51. This forms a groove 60 around the middle portion 54 as shown in FIG. 3, and the heater 70 and the insulating material 71 are housed in the groove 60. Furthermore, the outer peripheral surface 54c of the middle portion 54 (the bottom surface 63 of the groove 60) is covered with the heater 70, and the heater 70 is covered with the insulating material 71.

[0047] When the heater 70 is activated, the adapter 50 is heated, and the molten resin passing through the adapter flow path P1 is heated, thereby preventing or suppressing a decrease in the temperature of the molten resin passing through the adapter 50.

[0048] The heater 70 is not limited to a microheater. For example, the heater 70 can be replaced with a band heater or nichrome wire wound around the outer periphery of the adapter 50. The heater 70 can also be provided inside the adapter 50. For example, the heater 70 can be replaced with a cast-in heater embedded in the adapter 50. The heat insulating material 71 is not limited to a rigid heat insulating plate. The heat insulating material 71 can also be omitted.

[0049] <Temperature sensor> Referring again to Figure 2, a temperature sensor 72 using a thermocouple is inserted into the insertion hole 55 provided in the intermediate portion 54. More specifically, one end of the temperature sensor 72 including a temperature detection portion is inserted into the insertion hole 55, and the other end of the temperature sensor 72 is pulled out to the outside of the adapter 50.

[0050] The insertion hole 55 reaches the vicinity of the adapter flow path P1. Therefore, the temperature in the vicinity of the adapter flow path P1 can be detected by the temperature sensor 72. The temperature in the vicinity of the adapter flow path P1 reflects the temperature of the molten resin flowing through the adapter flow path P1.

[0051] The voltage (signal) output from the temperature sensor 72 is input to a heater control unit (not shown). The heater control unit controls the heater 70 based on the input signal. More specifically, the heater control unit controls the heat generation amount of the heater 70 so that the temperature in the vicinity of the adapter flow path P1 is maintained within a predetermined temperature range. In other words, the heater 70 is feedback-controlled based on the temperature measurement result of the temperature sensor 72.

[0052] When assembling the adapter 50 according to the procedure shown in FIG. 4, the temperature sensor 72 is inserted into the insertion hole 55 before the heater 70 is placed over the intermediate portion 54 .

[0053] <Pressing member> The injection nozzle 40 and the adapter 50 are fixed to each other by two pressing members 81 and 82. The pressing members 81 and 82 are substantially annular metal members, and face each other with the flange 52 of the adapter 50 sandwiched therebetween.

[0054] The pressing member 81 is disposed around the middle portion 54 of the adapter body 51, and covers the groove 60. From another perspective, the groove 60 and the pressing member 81 form a space for accommodating the heater 70 and the heat insulating material 71. On the other hand, the pressing member 82 is disposed around the base end of the injection nozzle 40, and surrounds the base end.

[0055] Pressing member 81 has a plurality of bolt holes 81a formed at equal intervals along the circumferential direction. Pressing member 82 has a plurality of through holes 82a formed at equal intervals along the circumferential direction. Pressing member 81 is positioned by positioning pin 83, and pressing member 82 is positioned by positioning pin 84. When pressing members 81 and 82 are positioned by positioning pins 83 and 84, corresponding bolt holes 81a and through holes 82a communicate with each other.

[0056] The presser members 81 and 82 are fixed to each other by a bolt 85 that passes through the through-hole 82a and is screwed into the bolt hole 81a. Therefore, when the bolt 85 is tightened, a force acts on the presser members 81 and 82 to move them closer to each other. This presses the presser member 81 against the flange 52 of the adapter 50. At the same time, the presser member 82 is pressed against the flange 42 of the injection nozzle 40, and the rear end surface of the injection nozzle 40 is pressed against the front end surface of the adapter body 51.

[0057] As a result, the injection nozzle 40 and the adapter 50 are fixed to each other. From another perspective, the injection nozzle 40 is fixed to the adapter 50 which is fixed to the heating cylinder 30. In other words, the injection nozzle 40 is attached to the heating cylinder 30.

[0058] The rear end of the injection nozzle 40 (the portion that protrudes rearward beyond the flange 42) enters inside the flange 52. Therefore, the rear end face of the injection nozzle 40 is pressed against the front end face of the adapter body 51 inside the flange 52. From another perspective, the adapter flow path P1 and the nozzle flow path P2 are connected inside the flange 52.

[0059] <Shut-off nozzle> 2 opens and closes the nozzle flow path P2. The shut-off nozzle 90 includes a needle valve 91 that is reciprocated by a drive mechanism (cylinder unit) (not shown). The tip of the needle valve 91 is inserted into the needle hole 43 provided in the injection nozzle 40.

[0060] The needle valve 91 is driven to reciprocate between a first position where its tip enters the nozzle flow path P2 and a second position where its tip retracts from the nozzle flow path P2. When the needle valve 91 moves from the second position to the first position, the nozzle flow path P2 is closed by the tip of the needle valve 91. On the other hand, when the needle valve 91 moves from the first position to the second position, the nozzle flow path P2 that was closed by the tip of the needle valve 91 is opened.

[0061] By providing the shut-off nozzle 90, it is possible to quickly and reliably stop the injection of molten resin from the injection nozzle 40. This advantage is particularly effective when the molten resin handled by the injection device 3 has high fluidity or foaming properties. On the other hand, in order to provide the shut-off nozzle 90, it is necessary to ensure space for disposing the needle valve 91 between the heating cylinder 30 and the injection nozzle 40. More specifically, it is necessary to position the injection nozzle 40 away from the heating cylinder 30.

[0062] In this embodiment, the overall length of the adapter 50 is set to a length that ensures a necessary and sufficient space for placing the needle valve 91 between the heating cylinder 30 and the injection nozzle 40. However, as the adapter 50 becomes longer, the surface area of ​​the adapter 50 increases, and the amount of heat dissipation increases. As a result, the temperature of the molten resin decreases while passing through the adapter 50, making it more likely that voids will occur.

[0063] The technical problems and findings of the present inventors regarding the occurrence of voids will be described in more detail below.

[0064] When an adapter 50 that functions as both an open nozzle and a shut-off nozzle is provided, as in the injection molding machine 1 of this embodiment, there is a problem that variations in the temperature of the injected molded product occur, which tends to reduce the dimensional accuracy of the molded product (leading to the occurrence of defective molded products). Furthermore, when the dimensional accuracy of the molded product decreases, voids occur, particularly in thick-walled portions, causing the dimensions of the thick-walled portions to tend to become thicker (enlarged or tend to become thicker).

[0065] As a result of extensive research into the above problem, the present inventors have discovered the following phenomenon: In an injection molding apparatus configured as described above, in the flow path of a raw material such as molten resin (hereinafter referred to as "molten resin") before it is delivered to the nozzle of the injection cylinder, the adapter 50 absorbs heat, causing a decrease in the temperature of the molten resin in the flow path through the adapter 50. It has been found that this decrease in temperature of the molten resin causes a loss of pressure, which generates gas in the molten resin, making it more likely to cause problems such as voids in the thick portions of the injection-molded product.

[0066] Therefore, in this embodiment, as described above, a heater (first adapter heater) 70 is provided in the adapter 50, making it possible to prevent or suppress a drop in the temperature of the molten resin. In the example shown in Figures 2 to 5, as described above, a microheater having a substantially cylindrical outer shape is arranged as the first adapter heater 70 on the outer circumferential surface 54c of the intermediate portion 54 in which the recess (groove 60) of the adapter 50 is formed.

[0067] Fig. 6 is a diagram illustrating another example of the configuration of the first adapter heater and an overview of temperature control, etc. As another example of the first adapter heater 70, as shown in Fig. 6, a band heater having a substantially band-shaped (band-shaped) outer shape may be arranged so as to be spirally wound around the same location as in Fig. 5, etc.

[0068] 7 is a diagram showing the arrangement of heaters other than the first adapter heater. In this embodiment, in order to achieve more precise temperature control of the flow path of the molten resin, a nozzle heater 45 is provided in the injection nozzle 40 to heat the nozzle flow path P2, and a cylinder heater 35 is provided in the heating cylinder 30 to heat the resin flow path inside the heating cylinder 30.

[0069] In one specific example, the nozzle heater 45 may be a substantially cylindrical micro-heater that is fitted over the outer surface of the injection nozzle 40. Alternatively, the nozzle heater 45 may be a band heater that is spirally wrapped around the outer surface of the injection nozzle 40.

[0070] Similarly, the cylinder heater 35 may be a substantially cylindrical micro-heater that is fitted over the outer surface of the heating cylinder 30. Alternatively, the cylinder heater 35 may be a band heater that is spirally wrapped around the outer surface of the heating cylinder 30.

[0071] In this embodiment, a heater (second adapter heater) 86 is also provided on the flange portion of the adapter 50 (i.e., outside the first adapter heater 70). As shown in FIGS. 5 and 7, in one specific example, a second adapter heater 86 is provided around the pressing members 81 and 82 to cover the pressing members 81 and 82. The illustrated second adapter heater 86 is a band heater wrapped around the outer periphery of the pressing members 81 and 82, and is switched between an activated state and an inactivated state as needed. By providing the second adapter heater 86, a decrease in the temperature of the molten resin is further prevented or suppressed. Note that the second adapter heater 86 is not limited to a band heater. For example, the second adapter heater 86 can be replaced with a micro heater similar to the first adapter heater 70 or another heater.

[0072] 6, the present embodiment is configured to include a control unit 100 that controls the first adapter heater 70 based on the temperature measurement results of the temperature sensor 72. The control unit 100 is configured from various hardware processors such as a CPU and an MPU that are provided inside or outside the device, and various memories such as a RAM and a flash ROM to and from which various programs and data are read and written.

[0073] Furthermore, the control unit 100 inputs (acquires) values ​​of the dimensional measurement results of the injection-molded product from the injection molding machine 1 via an input / output interface (not shown) or the like (see FIG. 6), and controls the output of the first adapter heater 70 based on these input values. Details of this control will be described later in the description of the flowchart in FIG. 8.

[0074] According to the injection molding machine 1 of this embodiment having the above-described configuration, the temperature of the molten resin passing through the adapter 50 can be actively adjusted to prevent or suppress a decrease in the dimensional accuracy of the injected molded product.

[0075] That is, in this injection molding machine 1, the output of the first adapter heater 70 is controlled by the control unit 100 to adjust the temperature of the adapter 50, thereby suppressing heat fluctuations and therefore temperature variations of the molten resin within the flow path in the area passing through the adapter 50 (resin flow path P1). Therefore, according to the injection molding machine 1 of this embodiment, it is possible to prevent or suppress a decrease in the dimensional accuracy of the injected molded product.

[0076] 6 or an external processor (not shown), depending on the environment, purpose, material (e.g., resin) used, etc. Meanwhile, for the sake of simplicity, in the specific example described below, it is assumed that the heaters 35, 45, 86 other than the first adapter heater 70 are always in operation (output on) while the injection molding machine 1 is in operation.

[0077] Fig. 8 is a flowchart mainly showing the process of output control of the first adapter heater. A specific example of temperature control of the first adapter heater 70 and the resin flow path will be described below with reference to the flowchart of Fig. 8 and Figs. 9 and 10.

[0078] In step S1 after the injection molding machine 1 (hereinafter sometimes simply referred to as "this device") starts operating, the control unit 100 operates (turns on the output) heaters other than the above-mentioned first adapter heater 70 (i.e., the cylinder heater 35, the adapter second heater 86, and the nozzle heater 45).

[0079] In this example, from step S1 onwards, operation of the heaters 35, 45, and 86 continues until operation of the apparatus is completed. As these heaters operate, the temperature in the flow path from the heating cylinder 30 to the injection nozzle 40 gradually rises, and when it reaches a practical temperature, the injection operation of the molded product begins.

[0080] Note that the control unit 100 may turn on the output of the first adapter heater 70 at step S1 as required for temperature adjustment or the like.

[0081] In step S2 after starting the injection operation of the molded product, the control unit 100 acquires the dimensions (wall thickness) of the molded product and the error values ​​thereof (see FIG. 6 as appropriate). It is desirable that the process of acquiring the dimensions (wall thickness) and the error values ​​thereof continues until the operation of this device is completed.

[0082] Figure 9 is a diagram illustrating an example of the process for measuring the dimensions of a molded product injected from this device. In Figure 9, various external devices are shown and the device is depicted in a simplified manner to clearly illustrate the manner in which the molded product moves. Figure 10 is a diagram illustrating an example of an injected molded product and an example of its dimension measurement.

[0083] In one specific example shown in Figure 9, a molded article M injected from this device is placed on a rotary table T that rotates, for example, clockwise, and moved to a predetermined position, from which it is then moved to a conveyor C by a pickup arm of a robot R (see the dotted arrow in Figure 9). The conveyor C is, for example, a belt conveyor, and transports the placed molded article M sequentially from left to right in Figure 9 (see the open arrow in Figure 9). Also, above the conveyor C, an image inspection device I is disposed, which includes a camera that captures images of the placed molded article M, an arithmetic processor, etc. In the image inspection device I, the arithmetic processor measures the dimensions of the molded article M based on the external shape of the molded article M captured by the camera, and measures the error relative to a specified value.

[0084] As shown in Figure 10, for example, the calculation processor of the image inspection device I measures the width dimension (indicated by arrow x in Figure 10) and height dimension (indicated by arrow z in Figure 10) of the main part of the molded product M, which will be the thickness measurement part, from the external shape of the molded product M that has been photographed, calculates the error (dimensional tolerance) from a predetermined specified value (a value required by the purchaser), and outputs the calculated value to the control unit 100 as the dimension measurement result (see Figure 6 as appropriate).

[0085] The above-mentioned turntable T, robot R, conveyor C, image inspection device I, etc., are well-known components and will not be described in further detail. Also, an intermediate device for branding or barcodes indicating product numbers, product names, etc. onto the molded products M can be disposed along the conveying path of the conveyor C, and such intermediate device is also well-known components and will not be described in detail.

[0086] Here, when the dimensions (wall thickness) of the molded product M are automatically measured using an image inspection device I described in Figure 9, the control unit 100 receives (acquires) such measurement values ​​from the image inspection device I via a wired or wireless input / output interface, etc.

[0087] As another example, when the dimensions (wall thickness) of the molded product M are measured manually, the thickness is measured using a known dimension measuring instrument, calipers, or the like. In this case, the control unit 100 may acquire such measured values, for example, through input operations by an operator using a keyboard or the like. The control unit 100 also acquires an error (deviation from the ideal value) by calculating the difference between the product specification value (i.e., ideal value) of the wall thickness of the molded product M currently being injected (hereinafter sometimes referred to as the "currently manufactured product") and the acquired measured value (measured value). Note that this difference calculation process may be performed by another external device that can be connected to or communicate with this device.

[0088] Thus, in step S3 after obtaining the error (deviation from the ideal value), the control unit 100 determines whether or not the error has become larger than the first range.

[0089] Here, the "first range" is the precision or error tolerance required by the purchaser of the current manufactured product, in this example, the range corresponding to the "upper limit of the thickness tolerance" among the upper and lower limit of the thickness tolerance, and more strictly, is set to a value slightly below the upper limit of the thickness tolerance. By setting it in this way, it is possible to prevent the production of defective products with excessive thickness and to minimize the decrease in yield.

[0090] If the control unit 100 determines that the acquired error is not larger than the first range (step S3: No), it determines that the thickness of the currently manufactured product satisfies the accuracy (error tolerance) required by the purchaser, and repeats the judgment of step S3.

[0091] On the other hand, if the control unit 100 determines that the acquired error is larger than the first range (step S3: Yes), it determines that the wall thickness of the currently manufactured product is large (tending to become thicker), and proceeds to step S4.

[0092] When the wall thickness of the currently manufactured product tends to increase in this way, it is believed that a thermal drop in the molten resin occurs within the flow path (adapter flow path P1) in the area passing through the adapter 50; in other words, the heat of the molten resin is being taken away by the adapter 50. Therefore, if this state is left as it is, a loss of pressure occurs as the thermal drop in the molten resin occurs, which generates gas in the molten resin, and is likely to cause problems such as voids in the thick wall portion of the injection-molded molded product M (see the area measured by arrows x and z in Figure 10). For this reason, the control unit 100 executes the process of step S4 to resolve the above-mentioned state.

[0093] In step S4, the control unit 100 activates (turns ON) the first adapter heater 70 of the adapter 50 (hereinafter, for simplicity, referred to solely as the "adapter heater 70"). Thereafter, the heat output from the adapter heater 70 is applied (heat transferred) to the adapter 50, and a large amount of heat is supplied to the flow path (adapter flow path P1) inside the adapter 50, and thereby to the molten resin passing through this flow path, thereby eliminating the condition in which the heat of the molten resin is taken away by the adapter 50. Furthermore, in this state, fluctuations in the heat (temperature) of the molten resin within the flow path (adapter flow path P1) in the area passing through the adapter 50, and therefore temperature variations, can be suppressed.

[0094] On the other hand, if too much heat is output (transferred) from the adapter heater 70, the opposite state occurs to the state in which the heat of the molten resin is taken away by the adapter 50, that is, the molten resin is excessively heated by the heat applied from the adapter 50, and in this case, a phenomenon occurs in which the wall thickness becomes smaller than the ideal value. To prevent or suppress such a situation, the control unit 100 executes the processes of step S5 and thereafter after the process of step S4.

[0095] In step S5, the control unit 100 determines whether or not the above-mentioned error (deviation from the ideal value) falls within a first range.

[0096] Here, if the control unit 100 determines that the acquired error does not fall within the first range (step S5: No), it determines that the thickness of the currently manufactured product is still larger than the ideal value, and repeats the determination in step S5.

[0097] On the other hand, if the control unit 100 determines that the acquired error falls within the first range (step S5: Yes), it determines that the thickness of the currently manufactured product satisfies the accuracy (error tolerance) required by the client, and proceeds to step S6.

[0098] In step S6, the control unit 100 controls the output or temperature of the adapter heater 70 so as to maintain (maintain within a certain range) the temperature of the flow path (adapter flow path P1) in the adapter 50. As described above, in this embodiment, in order to detect or estimate the temperature of the flow path in the adapter 50, a temperature sensor 72 is disposed in the adapter 50 (for example, on the inner wall along the flow path), and the detection result (measured temperature value) by the temperature sensor 72 is output to the control unit 100.

[0099] In the following step S7, the control unit 100 determines whether or not the above-mentioned error (deviation from the ideal value) falls below the second range.

[0100] Here, the "second range" is the precision or error tolerance required by the purchaser of the current manufactured product, in this example, the range corresponding to the "lower limit of the wall thickness" among the upper and lower limit of the wall thickness tolerance, and more strictly, is set to a value slightly above the lower limit of the wall thickness tolerance. By setting it in this way, it is possible to prevent the production of defective products with too small a wall thickness and to minimize the decrease in yield.

[0101] If the control unit 100 determines that the acquired error is not below the second range (in other words, is within the second range) (step S7: No), it determines that the thickness of the currently manufactured product satisfies the accuracy (error tolerance) required by the purchaser, and repeats the determination in step S7.

[0102] On the other hand, if the control unit 100 determines that the acquired error is below the second range (step S7: Yes), it determines that the thickness of the currently manufactured product is small (the thickness is tending to decrease), and proceeds to step S8.

[0103] In step S8, the control unit 100 performs a process to reduce the output or temperature of the adapter heater 70. Here, the control unit 100 may set the output of the adapter heater 70 to zero (OFF) as necessary. By reducing the output (temperature) of the adapter heater 70 in this way, the temperature of the adapter 50 decreases, and the temperature relationship between the adapter 50 and the molten resin passing through the flow path (adapter flow path P1) within the adapter 50 becomes optimal.

[0104] In the next step S9, the control unit 100 determines whether or not a signal to terminate the operation of the device has been detected. Here, the "signal to terminate the operation of the device" includes a signal indicating that the main power switch has been turned off, a termination instruction based on a user's operation input, an abnormality signal when an abnormality in the device is automatically detected, etc.

[0105] Here, if the control unit 100 determines that it has not detected a signal to terminate the operation of this device (step S9: No), it proceeds to step S3 and repeatedly executes the processes of steps S3 to S9 described above.

[0106] That is, if the temperature of the adapter 50 continues to decrease by reducing the output (temperature) of the adapter heater 70, the adapter 50 will again take away the heat of the molten resin passing through the flow path inside the adapter 50 (the above-mentioned tendency for the thickness to increase). Therefore, the control unit 100 performs the determination of step S3 again after processing step S8 (in other words, monitors whether or not a "tendency for the thickness to increase" has occurred), and repeats the processing of steps S3 to S9 until the operation of this device is completed.

[0107] In this way, the injection molding machine 1 of the present disclosure has a configuration for controlling the output of the adapter heater 70 (adapter heater) so as to suppress fluctuations in the temperature of the molten resin passing through the resin flow path (adapter flow path P1) inside the adapter 50. With this injection molding machine 1, it is possible to ensure a high level of dimensional accuracy in the manufactured molded products, and to significantly improve the substantial operating rate of the device and, in turn, the productivity of the device.

[0108] In the example described above in Figure 8, it is assumed that the heaters (35, 45, 86) other than the adapter heater 70 (adapter heater) are always (i.e., continuously) turned on at a fixed output value while the device is operating (from step S1 onwards).

[0109] As another example, if necessary for temperature adjustment or the like, a period may be set during operation of the device (after step S1) during which the outputs of the cylinder heater 35, the nozzle heater 45, and the second adapter heater 86 are appropriately turned off.

[0110] For example, the control unit 100 may perform control such as intermittently switching on / off the outputs of the heaters (35, 45, 86) other than the first adapter heater 70 so as to balance the temperature of the resin flow path P1 in the adapter 50 with the temperatures of the other flow paths (nozzle flow path P2 and the flow paths in the heating cylinder 30). By performing such control, it can be realized or expected that the effect of suppressing temperature fluctuations of the molten resin passing through the resin flow path P1 in the adapter 50 will be further improved.

[0111] The material of the resin molded product molded by the injection molding machine 1 of this embodiment is not particularly limited. Examples of materials for resin molded products include thermoplastic resins. More specifically, examples of materials for resin molded products include polypropylene (PP), polyphenylene sulfide (PPS), acrylic resin, polyester resin, and urethane resin.

[0112] On the other hand, when the temperature of a thermoplastic resin melted by shear heating drops, gas volatilization is likely to occur. In other words, voids are likely to occur in resin molded products made from thermoplastic resin melted by shear heating. Voids are particularly likely to occur in resin molded products made from low-viscosity polypropylene or polyphenylene sulfide.

[0113] Furthermore, voids that occur in resin molded products made of transparent resins such as acrylic resin, polyester resin, and urethane resin, or highly transparent resins, are easy to detect and can easily cause a decrease in the quality of the resin molded product.

[0114] In the past, when voids occurred in resin molded products, countermeasures were taken, such as eliminating sudden fluctuations in wall thickness in the mold, but even if costly modifications were made to the mold, it was not possible to fully prevent the occurrence of voids.

[0115] In contrast, the injection molding machine 1 of this embodiment, which is capable of adjusting the temperature of the adapter 50 located before the injection nozzle 40, can suppress the generation of gas volatile components that cause voids inside the injection nozzle 40. Therefore, it is possible to sufficiently prevent or suppress the generation of voids while saving costs required for mold modification.

[0116] Note that temperature maintenance and temperature adjustment of molten resin are also required for injection devices that do not have a shut-off nozzle. If an injection nozzle is attached to the heating cylinder of another injection device that does not have a shut-off nozzle using the adapter 50 of this embodiment, the temperature maintenance and temperature adjustment of molten resin can be achieved in that injection device as well.

[0117] The invention made by the inventor has been specifically described above based on an embodiment, but it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the spirit of the invention.

[0118] It is not essential to perform feedback control of the heater 70. For example, the heater 70 may be switched between an operating state and a non-operating state based on the temperature measurement result of the temperature sensor 72. Furthermore, the control unit 100 may be configured to control not only the output (temperature) of the first adapter heater 70 but also the output (temperature) of the second adapter heater 86.

[0119] The adapter 50 may be a single member. That is, the adapter 50 may be formed from a single metal member including the adapter body 51 and the flange 52. However, a split adapter 50 has the advantage of facilitating the assembly of the heater 70 and the heat insulating material 71. Furthermore, the adapter 50 is not limited to having the flange 52.

[0120] The number of temperature sensors 72 is not limited to one. For example, multiple insertion holes 55 may be provided in the intermediate portion 54, and a temperature sensor 72 may be inserted into each of the insertion holes 55. When multiple temperature sensors 72 are arranged, the temperature sensors 72 may be arranged along the longitudinal direction of the adapter flow path P1, or along the circumferential direction of the adapter flow path P1. Note that the temperature sensor 72 is not limited to a temperature sensor using a thermocouple. [Explanation of symbols]

[0121] 1 injection molding machine 2 Mold clamping device 3 Injection device 11,12 Mold 13 beds 14 Fixed plate 15 Mold clamping housing 16 Movable plate 17 Tie bar 18 Mold clamping mechanism 20 Foundation 21 Nozzle touch device 30 Heating Cylinder 31 Hopper 32 screws 33 Cover 35 Heater (cylinder heater) 40 injection nozzle 41 Injection port 42 Tsuba 43 Needle hole 45 Heater (nozzle heater) 50 Nozzle Adapter (Adapter) 51A, 51B Metallic parts 52 Tsuba 52b End face 53 Connection end 53a End face 54 Middle section 54c Outer surface 55 Insertion hole 56 Connecting part 60 grooves 61,62 Medial surface 63 bottom 70 Heater (first heater for adapter) 86 Heater (secondary heater for adapter) 71 Insulation 72 Temperature Sensor 81, 82 Pressing member 81a Bolt hole 82a Through hole 83,84 Locating pin 85 volts 90 Shut-off nozzle 91 Needle valve C Conveyor M Molded product I. Image inspection equipment R Robot P Resin flow path P1 Resin channel (adapter channel) P2 Resin flow path (nozzle flow path) T Rotary Table

Claims

1. a nozzle adapter for attaching the injection nozzle to the heating cylinder; a resin flow path communicating with the heating cylinder and the injection nozzle; an adapter heater provided around the resin flow path; a control unit that controls an output of the adapter heater so as to suppress fluctuations in the temperature of the molten resin passing through the resin flow path, a nozzle heater is disposed in the injection nozzle, and a cylinder heater is disposed in the heating cylinder, the control unit operates the nozzle heater and the cylinder heater during production of the molded product, and controls the output of the adapter heater according to a deterioration in the dimensional accuracy of the molded product. Injection molding machine.

2. the control unit controls the output of the adapter heater so as to increase the output of the adapter heater when the wall thickness of the molded product tends to increase during production of the molded product, and to decrease the output of the adapter heater when the wall thickness of the molded product tends to decrease.

2. The injection molding machine according to claim 1.

3. A nozzle adapter for attaching an injection nozzle to a heating cylinder; a resin flow path communicating with the heating cylinder and the injection nozzle; an adapter heater provided around the resin flow path; a control unit that controls an output of the adapter heater so as to suppress fluctuations in the temperature of the molten resin passing through the resin flow path, the control unit controls the output of the adapter heater so as to increase the output of the adapter heater when the wall thickness of the molded product tends to increase during production of the molded product, and to decrease the output of the adapter heater when the wall thickness of the molded product tends to decrease. Injection molding machine.

4. the control unit inputs a value relating to the wall thickness of the molded product during production of the molded product, and controls the output of the adapter heater based on the input value.

4. The injection molding machine according to claim 3.

5. the adapter heater includes a first heater and a second heater disposed outside the first heater; the control unit operates the second heater during the production of the molded product, and controls the output of the first heater according to a deterioration in the dimensional accuracy of the molded product.

5. The injection molding machine according to claim 1.

6. A nozzle adapter for attaching an injection nozzle to a heating cylinder; a resin flow path communicating with the heating cylinder and the injection nozzle; an adapter heater provided around the resin flow path; a control unit that controls an output of the adapter heater so as to suppress fluctuations in the temperature of the molten resin passing through the resin flow path, the adapter heater includes a first heater and a second heater disposed outside the first heater; the control unit operates the second heater during the production of the molded product, and controls the output of the first heater according to a deterioration in the dimensional accuracy of the molded product. Injection molding machine.

7. A temperature control method for an injection molding machine, comprising: controlling the output of an adapter heater disposed in a nozzle adapter for attaching the injection nozzle to the heating cylinder so as to suppress fluctuations in the temperature of the molten resin passing through a resin flow path in the nozzle adapter; controlling the output of the adapter heater so as to increase the output of the adapter heater when the wall thickness of the molded product tends to increase, and to decrease the output of the adapter heater when the wall thickness of the molded product tends to decrease; Temperature control method.

8. During operation of the injection molding machine, a nozzle heater disposed on the injection nozzle and a cylinder heater disposed on the heating cylinder are operated, and the output of the adapter heater is controlled according to the degree of deterioration in the dimensional accuracy of the molded product during production of the molded product. The temperature control method according to claim 7.

9. A temperature control method for an injection molding machine, comprising: controlling the output of an adapter heater disposed in a nozzle adapter for attaching the injection nozzle to the heating cylinder so as to suppress fluctuations in the temperature of the molten resin passing through a resin flow path in the nozzle adapter; During operation of the injection molding machine, a nozzle heater disposed on the injection nozzle and a cylinder heater disposed on the heating cylinder are operated, and the output of the adapter heater is controlled according to the degree of deterioration in the dimensional accuracy of the molded product during production of the molded product. Temperature control method.

10. inputting a value relating to the wall thickness of the molded product during the production of the molded product, and controlling the output of the adapter heater based on the input value; The temperature control method according to claim 8 or 9.

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