Injection molding machine

Abstract

A partial reflux injection function (5) is provided, which injects and fills the mold (2) with resin (R) in front of the screw head (4s), and at the same time, causes a predetermined amount of resin as reflux resin (Rm) to flow back to the screw body (4m) behind the screw head (4s) through the inner side and / or the outer peripheral side of the screw head (4s). Alternatively, a molding machine controller (C) may be configured to perform the following steps in sequence: a plasticizing step (Wi1), in which the resin in the heating cylinder (3) is plasticized by rotating the screw (4) inside the heating cylinder (3); an injection step (Wi2), in which a portion of the plasticized resin (R) accumulated in front of the screw head (4s) of the screw (4) is injected into the mold (2) by moving the screw (4) forward after the plasticizing step (Wi1); and a plasticizing promotion step (Wi3), in which a portion of the remaining portion of the resin (R) is returned as reflow resin (Rm) to the rear of the screw head (4s) after the injection step (Wi2).

Description

Technical Field

[0001] This invention relates to an injection molding machine that uses a specified injection pressure to inject resin into a mold after it has been closed by a specified clamping force to form a mold. Background Technology

[0002] In the past, injection molding machines are widely known for injecting resin into a mold consisting of a fixed mold and a movable mold after it has been closed by a clamping device with a specified clamping force using an injection device at a specified injection pressure. On the other hand, the applicant has proposed an injection molding machine with a specific molding mode based on a new molding method, which is different from the molding mode using a general molding method, i.e., the molding mode in which resin is metered on the injection device side and the metered resin is injected and filled into a mold after the movable mold and the fixed mold are fixed in position on the clamping device side. This injection molding machine is disclosed in Patent Document 1.

[0003] The purpose of this injection molding machine is to ensure high quality and homogeneity of molded products, even with low-viscosity resins that are easily affected by temperature, pressure, etc., and to simplify and facilitate the setting of molding conditions, thereby facilitating quality management. Furthermore, it improves mass production and economy by shortening the molding cycle time. Specifically, as a mold clamping device, a mold clamping device is used that can at least allow the resin to naturally compress along with the curing of the resin in the mold. The molding injection pressure and molding clamping force are predetermined and set to generate a specified mold gap between the movable mold and the fixed mold during injection filling and to produce qualified products. During production, the molding clamping force is used to close the mold clamping device, and the molding injection pressure is set to a limiting pressure to drive the injection device to inject and fill the resin relative to the mold.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. WO2011 / 161899 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, existing injection molding machines, exemplified by those with the specific molding modes described above, present the following challenges that need to be addressed.

[0009] In other words, when using an injection molding machine to produce molded products, various molding conditions such as injection speed, injection pressure, and resin temperature are usually set to match the type of product. However, the final molded product may have some degree of molding defects. In particular, depending on the type of product, there are molded products that are prone to molding defects. For example, high-cycle molded products with short plasticizing times that make it difficult to transfer sufficient heat to the resin, molded products using recycled granular materials that tend to have uneven particle shape compared to ordinary granules due to the incorporation of crushed materials, and molded products with large injection volumes that require large-volume plasticizing in one go are particularly prone to molding defects, which can easily lead to a decrease in yield (perfect product rate).

[0010] Therefore, in the past, this was addressed by stabilizing the high-precision setting and control of various molding conditions. For example, when plasticizing resin, this was addressed by setting the heating temperature with high precision and optimizing the screw rotation speed and plasticizing time. However, even with such measures, a considerable number of molding defects still occur in actual production, and the specific causes of these defects are often unknown, thus limiting the ability to ensure a high yield.

[0011] In particular, the inability to ensure a high yield rate in the production of large molded products and special resin molded products not only leads to reduced production efficiency and increased production costs, but also results in resource depletion and energy waste, requiring new injection molding machines to further improve the so-called limits of yield rate in the past.

[0012] The object of the present invention is to provide an injection molding machine that solves the problems existing in the prior art.

[0013] Methods for solving problems

[0014] To address the aforementioned issues, the injection molding machine M of the first aspect of the present invention comprises an injection molding machine having: a clamping device Mc that clamps a mold 2 consisting of a fixed mold 2c and a movable mold 2m using a predetermined clamping force; an injection device Mi that injects filling resin into the clamped mold 2 using a predetermined injection pressure; and a molding machine controller C that controls the clamping device Mc and the injection device Mi. The injection molding machine is characterized by having a partial reflow injection function 5, which, by causing the resin housed in the injection device Mi to... When the screw 4 in the hot cylinder 3 moves forward and injects resin R into the mold 2 at the front end of the screw head 4s, and a predetermined amount of resin that is part of the resin R flows back to the screw body 4m side behind the screw head 4s, the partial recirculation injection function 5, while injecting and filling the mold 2 with resin R at the front end of the screw head 4s, causes a predetermined amount of resin as recirculation resin Rm to flow back to the screw body 4m side behind the screw head 4s through the inner side and / or the outer peripheral side of the screw head 4s.

[0015] In this case, according to the preferred embodiment of the invention, the injection molding machine M of the first method preferably has a predetermined amount selected in the range of 10%-60% relative to the volume of resin R injected into the mold 2. Furthermore, when constructing the partial recirculation injection function unit 5, at least one recirculation path 11 for recirculating resin Rm is provided at the screw head 4s. More preferably, it can be configured to include an injection pressure additional setting function unit Fs that sets the injection pressure Pis during molding to a predetermined value higher than the injection pressure Pi when resin Rm is not recirculated. Alternatively, it can be configured to include a reversal control function unit Fc that reverses the screw 4. More preferably, the reversal control function unit Fc includes a reversal setting function unit Fcs that sets the period and rotational speed of reversing the screw 4. On the other hand, as a mold clamping device, a mold clamping device Mc is used that can at least naturally compress the resin R along with the curing of the resin R in the mold 2, and the following control function can be set in the molding machine controller C: the injection pressure (molding injection pressure) Pi and the clamping force (molding clamping force) Pc that can produce a specified mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling are predetermined and set in advance, and the mold clamping force (molding clamping force) Pc that can produce a qualified product is formed. During molding, the mold clamping device Mc is clamped by the molding clamping force Pc, and the molding injection pressure Pi is set to the limiting pressure Ps, thereby driving the injection device Mi to inject and fill the mold 2 with resin R.

[0016] Furthermore, to address the aforementioned issues, the second aspect of the injection molding machine M of the present invention comprises an injection molding machine having: a mold clamping device Mc that clamps a mold 2 consisting of a fixed mold 2c and a movable mold 2m by a predetermined clamping force; an injection device Mi that injects filling resin into the mold 2 after clamping by a predetermined injection pressure; and a molding machine controller C that controls the mold clamping device Mc and the injection device Mi. The injection molding machine is characterized in that the molding machine controller C injects and fills the mold 2 with resin R in front of the screw head 4s at the front end of the screw 4 housed in the heating cylinder 3 of the injection device Mi by moving the screw 4 forward. When the mold 2 is used to return a predetermined amount of resin, which is part of the resin R, to the screw body 4m side behind the screw head 4s, the molding machine controller C sequentially executes the following steps: plasticizing step Wi1, in which the resin in the heating cylinder 3 is plasticized by rotating the screw 4 in the heating cylinder 3; injection step Wi2, after the plasticizing step Wi1 is completed, a portion of the plasticized resin R accumulated in front of the screw head 4s of the screw 4 is injected into the mold 2 by moving the screw 4 forward; and plasticizing promotion step Wi3, after the injection step Wi2 is completed, a portion of the remaining part of the resin R is returned to the rear of the screw head 4s as return resin Rm.

[0017] In this case, according to the preferred embodiment of the invention, the injection molding machine M of the second method can use an injection device with a flow-stop nozzle (or valve nozzle) 51 in the injection device Mi. Furthermore, as a clamping device, a clamping device Mc that can at least naturally compress the resin R along with the curing of the resin R within the mold 2 is used, and the molding machine controller C can be configured with the following control functions: The injection pressure (molding injection pressure) Pi and the clamping force (molding clamping force) Pc that can produce a predetermined mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling are predetermined and set in advance; during molding, the clamping device Mc is clamped by the molding clamping force Pc, and the molding injection pressure Pi is set to a limiting pressure Ps, thereby driving the injection device Mi to inject and fill the mold 2 with resin R. Furthermore, in the plasticizing accelerator step Wi3, when the plasticized accumulated resin R is recirculated, it can be recirculated by pressurizing the screw 4 forward or by reversing the screw 4. On the other hand, when performing the plasticizing accelerator step Wi3, an auxiliary plasticizing process (S121) can be performed before performing the actual plasticizing accelerator process (S122) to ensure the amount of recirculated resin Rm is reached. In addition, an auxiliary plasticizing process section and a plasticizing accelerator process section can be set up, and the combination process of the auxiliary plasticizing process section (S201) and the plasticizing accelerator process section (S202) based on this setting can be repeated for a predetermined number of times N or within the allowable time of the plasticizing accelerator step Wi3.

[0018] Invention Effects

[0019] The injection molding machine M according to this invention has the following significant effects.

[0020] (1) By moving the screw 4 housed in the heating cylinder 3 of the injection unit Mi forward, resin R at the front of the screw head 4s at the front end of the screw 4 is injected into the mold 2, and a predetermined amount of resin that is part of the resin R is returned as recirculating resin Rm to the screw body 4m side behind the screw head 4s. Therefore, an injection molding machine M can be provided as a new injection molding method that can significantly improve the yield of the final molded product, and in particular, can achieve a yield that can further improve the previously so-called limit. As a result, it is possible to improve production efficiency and reduce production costs in the production of large molded products, special resin molded products, etc., and can also effectively contribute to avoiding resource depletion and energy waste.

[0021] (2) According to the preferred method, in the injection molding machine M of the first method, if the amount (prescribed amount) of the refluxing resin Rm is selected to be in the range of 10-60 [%) relative to the capacity of the resin R injected into the mold 2, the production efficiency and yield in the production of the molded product can be well balanced. Therefore, from the point of view of ensuring production efficiency and ensuring yield, the two can be optimized.

[0022] (3) According to the preferred method, in the injection molding machine M of the first method, when the partial reflow injection function unit 5 is configured, if at least one reflow path 11... for reflow of resin Rm is provided in the screw head 4s, it can be achieved by changing or adding processing to the screw head 4s. Therefore, it can be implemented easily and at low cost, and it can also be implemented as a versatile method that can be easily applied to existing injection molding machines.

[0023] (4) According to the preferred embodiment, in the injection molding machine M of the first embodiment, when the component reflow injection function unit 5 is configured, if an injection pressure additional setting function unit Fs is provided to set the injection pressure Pis during molding to be higher than the injection pressure Pi when the resin R does not reflow by a predetermined amount, then even if the configuration is configured to provide a reflow path 11..., the amount of reflow resin Rm (reflow rate) can be arbitrarily set by the injection pressure additional setting function unit Fs. Therefore, the reflow rate can be easily set, and the influence on the original amount of resin R injected and filled relative to the mold 2 (filling amount) can be avoided.

[0024] (5) According to the preferred method, in the injection molding machine M of the first method, when the partial reflow injection function unit 5 is configured, if the reversal control function unit Fc that reverses the screw 4 is provided, then there is no need to change the shape of the screw 4 itself. Therefore, reflow can be achieved by controlling the screw 4, which can further facilitate implementation and further improve versatility.

[0025] (6) According to the preferred embodiment, when the reverse control function unit Fc is configured, if a reverse setting function unit Fcs is provided to set the period and rotation speed of the screw 4 to reverse, the recirculation flow rate of the recirculation resin Rm can be set by the reverse setting function unit Fcs. Therefore, any recirculation flow rate can be easily set, and the influence on the original filling amount relative to the injection filling of the mold 2 can be avoided.

[0026] (7) Preferably, as a mold clamping device, a mold clamping device Mc is used that is at least capable of naturally compressing the resin R along with the curing of the resin R within the mold 2. Furthermore, if the molding machine controller C is configured with the following control function: the injection pressure (molding injection pressure) Pi and the clamping force (molding clamping force) Pc that generate a predetermined mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling are predetermined and set in advance, and the molding clamping force Pc that enables the molding of a qualified product is used to clamp the mold clamping device Mc during molding, and the molding injection pressure Pi is... By setting the pressure Ps to limit the injection device Mi and injecting resin R into the mold 2, the molding method proposed by the applicant (refer to International Publication WO2011 / 161899) can be applied. This is a specific molding mode in which the state of the injection device Mi side is almost unaffected by the metering process. Therefore, it is possible to improve production efficiency and reduce production costs. From the viewpoint of helping to avoid resource depletion and energy waste, this can be implemented as the best approach.

[0027] (8) According to a preferred embodiment, in the injection molding machine M of the second embodiment, if an injection device with a flow-stop nozzle (or valve nozzle) 51 is used in the injection device Mi, the nozzle orifice 3ne can be closed as needed. Therefore, the plasticizing promotion process Wi3 can also be performed between the cooling process Wc4, the mold opening process Wc5, and the molded article removal process Wc6. As a result, sufficient plasticizing promotion treatment can be performed in time, and the injection molding machine M of the present invention can be implemented more reliably and effectively.

[0028] (9) According to the preferred embodiment, in the injection molding machine M of the second embodiment, when the resin R is recirculated, if the recirculation is controlled by the forward pressure control function of the screw 4, then after the injection process Wi2 is completed and the resin in the mold 2 has fully cured, the forward pressure of the screw 4 can be increased without affecting the molded part in the mold 2, and thus the recirculation can be achieved using this pressure. Therefore, this can be easily implemented by providing a small recirculation path that does not cause recirculation due to the molding injection pressure Pi, or a recirculation path with an opening and closing function, etc., at the screw head 4s.

[0029] (10) According to the preferred method, in the injection molding machine M of the second method, when the resin R is recirculated, if the recirculation is caused by the forward pressure control function and the reverse control function of the screw 4, the recirculation flow rate can be adjusted by the reverse control of the screw 4. Therefore, by selecting the conditions such as the reversal period and the rotation speed, any recirculation flow rate of the resin Rm can be easily and accurately set.

[0030] (11) According to the preferred embodiment, in the injection molding machine M of the second embodiment, when performing the plasticizing accelerator step Wi3, if an auxiliary plasticizing treatment (S121) is performed before performing the actual plasticizing accelerator treatment (S122) to ensure the amount of reflow resin Rm, then at the end stage of the injection step Wi2, even if the plasticized accumulated resin R accumulated in front of the screw 4 becomes a small amount, the necessary amount of reflow resin Rm can be ensured by performing the auxiliary plasticizing treatment (S121) for a specified time.

[0031] (12) According to a preferred embodiment, in the injection molding machine M of the second embodiment, when performing the plasticizing accelerator step Wi3, if an auxiliary plasticizing treatment section and a plasticizing accelerator step are set, and the combination of the auxiliary plasticizing treatment section (S201) and the plasticizing accelerator step (S202) based on this setting is repeated for a predetermined number of times N or within the allowable time of the plasticizing accelerator step Wi3, then, for example, in the case of large molded articles where the cooling time is relatively long, such repeated processing can achieve efficient utilization of the cooling time. As a result, the plasticizing treatment of the resin R can be performed more uniformly and densely, thereby contributing to further improvement of the quality of the molded article and the yield. Attached Figure Description

[0032] Figure 1 This is an overall structural diagram of an injection molding machine according to a preferred embodiment of the present invention.

[0033] Figure 2 This is a part of the injection unit of the injection molding machine shown in the first embodiment of this invention. Figure 1 A side view of the cross section of the imaginary circle A.

[0034] Figure 3 It is a bar graph showing the magnitudes of various physical quantities when reflow is performed and when no reflow is performed by the injection molding machine.

[0035] Figure 4 This is a flowchart illustrating the molding steps of an injection molding method using this injection molding machine.

[0036] Figure 5 This is an explanatory diagram showing the movement of the resin during the plasticizing process of the injection molding machine.

[0037] Figure 6 This is an explanatory diagram showing the movement of the resin during the molding process of the injection molding machine.

[0038] Figure 7 This is a diagram showing the relationship between mold clearance and time in the molding process of this injection molding machine.

[0039] Figure 8 This is a comparison chart showing the standard deviation of the mold displacement deviation of the injection molding machine and the mold displacement deviation without reflow.

[0040] Figure 9 This is part of the injection unit of the injection molding machine shown in the second embodiment of this invention. Figure 1 A side view of the cross section of the imaginary circle A.

[0041] Figure 10 This is used to illustrate the molding steps of the injection molding method using this injection molding machine. Figure 4 The detailed steps of step SN are shown in the diagram.

[0042] Figure 11 This is a graph showing the relationship between screw reversal and return flow when using this injection molding machine.

[0043] Figure 12 This is part of an injection device that illustrates a variation of the first embodiment of this method. Figure 1 A side view of the cross section of the imaginary circle A.

[0044] Figure 13 This is part of the injection device shown as a variation of the second embodiment of this implementation. Figure 1 A side view of the cross section of the imaginary circle A.

[0045] Figure 14 This is a diagram showing the relationship between mold gap and time in the injection molding process of the injection molding method using the injection molding machine of the third embodiment of this implementation.

[0046] Figure 15 The module system shows the process diagrams of each step of the injection molding method using this injection molding machine.

[0047] Figure 16 This is a flowchart illustrating the molding steps of an injection molding method using this injection molding machine.

[0048] Figure 17 It shows in detail Figure 16 The flowchart shows the processing content of step S30 in the flowchart.

[0049] Figure 18 This is a schematic diagram illustrating the state of the mold and injection device in the mold closing process of an injection molding method using this injection molding machine.

[0050] Figure 19This is a schematic diagram illustrating the state of the mold and injection device in the natural clearance generation process of the injection molding method using this injection molding machine.

[0051] Figure 20 This is a schematic diagram illustrating the state of the mold and injection device in other natural clearance generation processes of the injection molding method using this injection molding machine.

[0052] Figure 21 This section shows in detail variations of the third embodiment. Figure 17 The flowchart shows the processing content of step S30 in the flowchart.

[0053] Figure 22 This is a schematic structural diagram of the flow-stop nozzle of the injection molding machine in this modified example.

[0054] Label Explanation

[0055] 2: Mold; 2c: Fixed mold; 2m: Movable mold; 3: Heating cylinder; 4: Screw; 4s: Screw head; 4m: Screw body; 5: Partial reflow injection function; 11…: Reflow path; 51: Stop-flow nozzle (or valve nozzle); M: Injection molding machine; Mc: Mold clamping device; Mi: Injection device; C: Molding machine controller; R: Resin; Rm: Reflow resin; Pis: Injection pressure; Pi: Injection pressure (molding injection pressure); Pc: Molding clamping force; Fs: Injection pressure additional setting function; Fc: Reverse control function; Fcs: Reverse setting function; Lm: Mold clearance; Wi1: Plasticizing process; Wi2: Injection process; Wi3: Plasticizing promotion process; (S121): Auxiliary plasticizing treatment; (S122): Plasticizing promotion treatment; (S201): Auxiliary plasticizing treatment section; (S202): Plasticizing promotion treatment section. Detailed Implementation

[0056] Next, preferred embodiments of the present invention will be listed and described in detail with reference to the accompanying drawings.

[0057] First, refer to Figure 1 The main structure of the injection molding machine M in this embodiment will be described.

[0058] exist Figure 1In this designation, M represents an injection molding machine, which includes an injection unit Mi and a mold clamping unit Mc. The injection unit Mi has a heating cylinder 3, which has an injection nozzle 3n at its front end and a hopper 21 at its rear end. A screw 4 is inserted through the heating cylinder 3, and a screw drive unit 23 is located at the rear end of the heating cylinder 3. The screw drive unit 23 has an injection cylinder (hydraulic cylinder) 24 with a built-in single-rod injection plunger 24r. A plunger rod 24rs protruding forward from the injection cylinder 24 is coupled to the rear end of the screw 4. Furthermore, the shaft of a metering motor (hydraulic motor) 25 mounted on the injection cylinder 24 is splinedly coupled to the rear end of the injection plunger 24r. 26 represents an injection unit moving cylinder that moves the injection unit Mi forward and backward to contact or release the nozzle relative to the mold 2. Thus, the injection unit Mi can bring the injection nozzle 3n into contact with the nozzle of the mold 2, thereby injecting molten (plasticized) resin R into the cavity of the mold 2. Figure 5 ).

[0059] On the other hand, the mold clamping device Mc is a hydraulic mold clamping device that uses direct pressure to displace the movable mold 2m via the drive plunger 27r of the mold clamping cylinder (hydraulic cylinder) 27. The mold clamping device Mc has a fixed platen 28 that is positioned and separately disposed, and a movable platen 30 that is slidably mounted on a plurality of connecting rods 29… erected between the fixed platen 28 and the mold clamping cylinder 27. The front end of the plunger rod 27rs, which protrudes forward from the mold clamping cylinder 27, is fixed to the movable platen 30. Furthermore, a fixed mold 2c is mounted on the fixed platen 28, and a movable mold 2m is mounted on the movable platen 30, forming mold 2. Thus, the mold clamping cylinder 27 can perform mold opening and closing and mold clamping relative to mold 2. In this case, since the mold clamping device Mc uses a mold clamping cylinder (hydraulic cylinder) 27, the mold clamping device Mc is able to perform natural compression of the resin R at least as the resin R in the mold 2 cures.

[0060] On the other hand, injection molding machine M has Figure 1 The hydraulic circuit 35 shown includes a variable discharge hydraulic pump 36 and a valve circuit 37, which serve as the hydraulic drive source, and a pump circuit 38 for driving and controlling the hydraulic pump 36. The hydraulic pump 36 has a built-in swashplate (not shown). Increasing the swashplate angle (swashplate angle) increases the pump piston stroke, thereby increasing the discharge flow rate; conversely, decreasing the swashplate angle decreases the pump piston stroke, thereby reducing the discharge flow rate. Therefore, by setting the swashplate angle to a predetermined angle, a fixed discharge flow rate (maximum capacity) can be set to a predetermined value.

[0061] Furthermore, the outlet of the hydraulic pump 36 is connected to the primary side of the valve circuit 37. The secondary side of the valve circuit 37 is also connected to the injection cylinder 24, metering motor 25, mold clamping cylinder 27, ejector cylinder 31, and injection device moving cylinder 26 in the injection molding machine M. Therefore, the valve circuit 37 has switching valves (solenoid valves) connected to the injection cylinder 24, metering motor 25, mold clamping cylinder 27, ejector cylinder 31, and injection device moving cylinder 26, respectively. Each switching valve is primarily composed of one or more valve components and necessary auxiliary hydraulic components, and at least has switching functions related to the supply, stop, and discharge of working oil to the injection cylinder 24, metering motor 25, mold clamping cylinder 27, ejector cylinder 31, and injection device moving cylinder 26.

[0062] Pump circuit 38 can change the discharge flow rate and discharge pressure by controlling the pump motor (servo motor) of variable discharge hydraulic pump 36. Based on this, it can drive and control the injection cylinder 24, metering motor 25, mold clamping cylinder 27, ejection cylinder 31, and injection device moving cylinder 26, and can control each action step in the molding cycle. Thus, if a variable discharge hydraulic pump 36 that can set a fixed discharge flow rate by changing the ramp angle is used, the pump capacity can be set to a fixed discharge flow rate (maximum capacity) of a specified size, and the discharge flow rate and discharge pressure can be changed based on the fixed discharge flow rate, so control can be performed easily and smoothly.

[0063] In addition, injection molding machine M has Figure 1 The control system 41 shown has a control function for performing molding processes based on a specific molding mode. This specific molding mode is as follows: a molding injection pressure Pi and a molding clamping force Pc that generate a predetermined mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling are predetermined and set to enable the molding of a qualified product. During molding, the molding clamping force Pc is used to clamp the mold clamping device Mc, and the molding injection pressure Pi is set to a limiting pressure Ps, driving the injection device Mi to inject resin R relative to the mold 2.

[0064] The control system 41 includes a molding machine controller C, which has a molding machine controller body 42c and a display 42d attached to the molding machine controller body 42c. The molding machine controller body 42c has computer functions with built-in hardware such as a CPU and internal memory. The attached internal memory 42m has a program area 42mp that stores various programs containing control programs (software) for performing various arithmetic processing and various control processing (sequential control), and a data area 42md that can store various types of data (database). Therefore, the software for executing the aforementioned specific molding mode is stored in the program area 42mp, and can function as a specific molding mode function unit Fa.

[0065] Furthermore, the display 42d includes a display body 42dd and a touch panel 42dt attached to the display body 42dd. The display body 42dd and the touch panel 42dt are connected to the molding machine controller body 42c via a display interface (not shown). Therefore, various setting and selection operations can be performed through the touch panel 42dt.

[0066] In addition, various sensor types 43, including a mold gap sensor that detects the mold gap Lm, and various switch types 44 are connected to the molding machine controller body 42c, and the aforementioned pump circuit 38 and valve circuit 37 are also connected.

[0067] Next, refer to Figures 1-13 The structure and function of the main parts of the injection molding machine M in this embodiment will be described in detail.

[0068] In addition to the main structure described above, the injection molding machine M of this embodiment also has a partial reflow injection function 5, which constitutes a major part of the present invention. That is, the partial reflow injection function 5 has the following function: while injecting and filling the mold 2 with resin R in front of the screw head 4s at the front end of the screw 4 by moving the screw 4 of the heating cylinder 3 housed in the injection device Mi forward, a predetermined amount of reflow resin Rm, which is part of the resin R, flows back to the screw body 4m side behind the screw head 4s through the inner side of the screw head 4s and / or the outer peripheral side of the screw head 4s.

[0069] Therefore, as Figure 1 As shown, the molding machine controller C stores software for enabling the partial backflow injection function unit 5 to function. Through this software, the injection pressure additional setting function unit Fs, the reverse control function unit Fc, and the reverse setting function unit Fcs (described later) can each function.

[0070] Hereinafter, a first embodiment and a second embodiment will be listed to describe an injection molding machine M having a first embodiment having a partial reflow injection function 5, which is a major part of the present invention.

[0071] [First Embodiment]

[0072] First, refer to Figures 1-3 The structure of the partial reflux injection function unit 5 of the injection molding machine M in the first embodiment will be described.

[0073] Figure 2 yes Figure 1 The enlarged view of a portion of the injection device Mi in the injection molding machine M shown, namely the imaginary line circle A, shows a portion of the injection device Mi having the partial backflow injection function unit 5 of the first embodiment.

[0074] exist Figure 2 In the diagram, 4 represents a screw, which has a helical screw thread 4f on the circumferential surface of the screw body 4m, and a screw head 4s at the front end of the screw 4. The screw head 4s, as exemplified, has a conical front end portion 4sc at its front end. The rear end face of this conical front end portion 4sc is mounted to the front end face of the screw body 4m via a mounting shaft portion 4sj disposed in the axial direction Ds. A cylindrical check valve portion 4sn, capable of moving back and forth, is disposed between the conical front end portion 4sc and the screw body 4m.

[0075] Furthermore, the function of the check valve in a typical injection molding machine molding mode is as follows. First, in the metering process, resin is metered from the screw body side towards the front of the screw head; therefore, the check valve moves forward to an open position along with the resin movement. That is, it allows the resin to move forward. Second, in the injection process, the metered resin pressure acts backward, causing the check valve to move backward to a closed position. Thus, the backflow of resin backward is prevented by the check valve. Therefore, the check valve is cylindrical in shape, with its outer circumferential surface abutting against the inner circumferential surface of the heating cylinder with almost no gap, and the resin flow path is cut off inside the inner circumferential surface of the check valve.

[0076] On the other hand, in the injection molding machine M of the first embodiment of the present invention, such as Figure 2 As shown, the check valve part 4sn is integrally formed into a cylindrical shape, and at least one return passage 11... is formed on its outer peripheral surface to allow the return resin Rm to pass backward. In the example, multiple return passages 11... are formed at equal intervals along the circumference. If such a return passage 11... is provided, it can be achieved by changing or additionally processing the screw head 4s, so it can be implemented easily and at low cost, and it can also be implemented in a versatile way that can be applied to existing injection molding machines.

[0077] In this case, it is preferable that the return flow path 11 is formed by a straight groove parallel to the axial direction Ds, and the size of the cross-sectional area of ​​the return flow path 11 is selected such that the amount of return resin Rm (return flow rate) is in the range of 10-60% relative to the capacity of resin R injected into the mold 2. If selected in this way, production efficiency and yield in the production of molded products can be well balanced, and thus, from the viewpoint of ensuring production efficiency and ensuring yield, both can be optimized.

[0078] In addition, Figure 2 In the diagram, 12 represents a resin passage located between the inner circumferential surface of the check valve portion 4sn and the outer circumferential surface of the mounting shaft portion 4sj, and 13… represents a plurality of resin passages formed on the outer circumferential surface of the cone front end portion 4sc. Therefore, the resin passages 13… are each formed with cuts at equal intervals in the circumferential direction. Thus, even when the check valve portion 4sn moves forward to the open position and abuts against the rear end face of the cone front end portion 4sc, the resin passages 12 and 13… can maintain communication, and if the check valve portion 4sn moves backward to the closed position and abuts against the front end face of the screw body portion 4m, the resin passages 12 are blocked.

[0079] Furthermore, the reflow rate of the reflow resin Rm is affected not only by the presence of the reflow path 11…, but also by the magnitude of the injection pressure during molding. Therefore, in the partial reflow injection function unit 5 of the first embodiment, an injection pressure additional setting function unit Fs is provided in the molding machine controller C, which can change the molding injection pressure Pi (limiting pressure Ps) described later. This injection pressure additional setting function unit Fs has at least the function of setting the injection pressure Pis during molding to a predetermined value higher than the molding injection pressure Pi when the resin R does not reflow.

[0080] If such an injection pressure additional setting function unit Fs is provided, even when configured with a recirculation path 11..., the recirculation flow rate of the recirculating resin Rm can be arbitrarily set by the injection pressure additional setting function unit Fs. Therefore, the recirculation flow rate can be easily set, and the influence on the original amount of resin R (filling amount) injected and filled relative to the mold 2 can be avoided. Therefore, it is preferable to set the injection pressure Pis during recirculation molding in a manner that does not affect the original molding based on the molding injection pressure Pi when not recirculating.

[0081] Figure 3 The diagram shows the magnitudes of various physical quantities during molding when resin R does not reflow (no reflow) and when a specified amount of reflowed resin Rm reflows (with reflow). Figure 3In this context, the peak injection pressure Pp corresponds to the limiting pressure Ps, which will be described later. Therefore, an example is shown where the peak injection pressure Pp (limiting pressure Ps) without backflow is 50.5 MPa. In contrast, in the injection molding method with backflow, i.e., using the injection molding machine M of this embodiment, it is set to a value slightly larger than the value without backflow, 52.5 MPa. This peak injection pressure Pp (limiting pressure Ps) can be set using the injection pressure additional setting function Fs.

[0082] The results showed that the injection volume Qi was 71.2 [cubic centimeters] without backflow, while it increased to 98.0 [cubic centimeters] with backflow. Therefore, the backflow rate was {(98.0-71.2) / 71.2}×100=37.6 [%], ensuring a range of 10-60 [%]. Furthermore, the following results were also shown: the screw injection stroke Xi during injection was 44.8 [mm] without backflow, while it increased to 61.4 [mm] with backflow.

[0083] Thus, when the reflow injection function unit 5 is configured, if an injection pressure additional setting function unit Fs is provided that sets the injection pressure Pis during molding to be higher than the injection pressure Pi when the resin R does not reflow by a predetermined amount, then even if the configuration is configured to provide a reflow path 11..., the reflow rate of the reflow resin Rm can be arbitrarily set by the injection pressure additional setting function unit Fs. Therefore, the reflow rate can be easily set, and the influence on the original amount (filling amount) of resin R injected and filled relative to the mold 2 can be avoided.

[0084] Next, refer to Figures 1-8 The molding steps of the injection molding method using the injection molding machine M of the first embodiment will be described.

[0085] First, a specific molding pattern used in the injection molding method of the injection molding machine M in this embodiment is preset. Furthermore, the basic molding steps of this specific molding pattern are the same as those described in the aforementioned Patent Document 1 (International Publication No. WO2011 / 161899) filed by the applicant.

[0086] The following describes the pre-set steps. First, the injection pressure, which becomes the injection condition for the injection unit Mi, is initially set using the molding machine controller body 42c. This injection pressure can be set based on the capacity (driving force) of the injection unit Mi. Next, the clamping force, which becomes the clamping condition for the clamping unit Mc, is initially set using the molding machine controller body 42c. This clamping force can be set based on the capacity (driving force) of the clamping unit Mc.

[0087] Next, the molding injection pressure Pi used in production is determined by optimizing the initially set injection pressure, and the molding clamping force Pc used in production is determined by optimizing the initially set clamping force. The optimization of the clamping force and injection pressure can be performed as follows: First, a trial molding is conducted using the initially set clamping force and injection pressure. When the clamping force is set relatively high, burrs are not generated, and porosity, warping, and venting become undesirable or slightly undesirable. Then, the clamping force and injection pressure are varied in stages, and trial molding is performed at each stage. The size of the mold gap Lm between the fixed mold 2c and the movable mold 2m is obtained by a mold gap sensor (not shown, such as a reflective optical sensor), and displayed on the waveform display section of the screen 42d. The quality of the molded product is then observed.

[0088] exist Figure 7 The waveform display shows the changing state of the mold gap Lm. Figure 7 During the injection process, after the injection begins, mold 2 starts to open at time t0, and the maximum mold gap Lmp is generated at time tp. Afterwards, it shifts in a gradually closing direction, eventually stabilizing at the residual mold gap Lmr.

[0089] Furthermore, the injection pressure can be optimized to achieve the aforementioned specified mold gap Lm (approximately 0.03-0.30 mm) between the movable mold 2m and the fixed mold 2c during injection filling, while ensuring the production of qualified products. Specifically, by appropriately varying the injection pressure, the size at which the resin R begins to abnormally fill the mold 2 can be selected. Additionally, the determined molding injection pressure Pi is set as a limiting pressure Ps relative to the injection pressure used during production.

[0090] In this case, as described above, the injection pressure additional setting function Fs is used to set the injection pressure Pis during molding to a value higher than the injection pressure Pi under non-reflow conditions by a predetermined amount. In an example, a slightly larger value (52.5 MPa) is set as the injection pressure Pis during molding, relative to an injection pressure Pi of 50.5 MPa, and this injection pressure Pis is set as the limiting pressure Ps. On the other hand, by changing the conditions and repeating these trial moldings, a clamping force that satisfies the aforementioned conditions can be selected. The selected clamping force is set as the molding clamping force Pc when the mold 2 is closed during production. In this case, the magnitudes of the clamping force and injection pressure can be arbitrarily set by the operator, or they can be determined automatically or semi-automatically using the automatic tuning function or the like of the injection molding machine M.

[0091] Next, refer to Figure 4The flowchart shown illustrates the specific processing steps during production.

[0092] During production, firstly, according to the processing steps of a specific molding mode that forms the basis of the injection molding method using the injection molding machine M of this embodiment, a plasticizing treatment of resin R is performed (step S1). In this case, since a predetermined amount of reflowed resin Rm, which will be described later, is also mixed in, this plasticizing treatment includes a plasticizing promotion treatment. During the plasticizing treatment, the metering motor 25 of the injection device Mi is driven to rotate by controlling the hydraulic pump 36 and switching the valve circuit 37.

[0093] Furthermore, in a specific molding mode, the precise metering process of resin R, as required in conventional molding methods, is not necessary. That is, in this specific molding mode, the injection process only requires injection until the resin R fills the cavity; therefore, the resin R in the plasticizing process only needs to be mostly plasticized. In other words, although the metering action is performed as in a conventional metering process, precise metering control is not required to obtain accurate values. In particular, the injection molding machine of this embodiment includes a reflow action based on the partial reflow injection function 5, which reflows a portion of the remaining plasticized resin R (reflow resin Rm), i.e., a reflow rate (Rm) in the range of 10-60% relative to the injected resin amount (R). Therefore, it is preferable to ensure a plasticizing amount of at least twice the volume (1 stroke) of the molded article.

[0094] Figure 5 The action of resin R during plasticizing is shown. In this case, screw 4 rotates at a set rotational speed and for a set period. Through the rotation of screw 4, resin R is conveyed forward, thus... Figure 5 As indicated by the middle arrow D1…, the resin R on the screw body 4m side accumulates forward through the screw head 4s. That is, the resin R moves forward from the screw body 4m side, thereby affecting the check valve section 4sn. Figure 5 As the forward open position is moved, the resin R on the screw body 4m side passes through the resin passage 12 inside the check valve 4sn and the resin passage 13 of the cone front end 4sc, and thus reaches the front of the cone front end 4sc. As a result, the plasticized resin R gradually accumulates in the heating cylinder 3 in front of the cone front end 4sc, and the screw 4 moves backward along with the accumulation.

[0095] Additionally, by controlling the hydraulic pump 36 and switching the valve circuit 37, the clamping cylinder 27 of the clamping device Mc is driven to close the mold 2 with the clamping force becoming the set molding clamping force Pc (step S2). Afterwards, by switching the valve circuit 37 and controlling the hydraulic pump 36, the injection cylinder 24 of the injection device Mi is driven to begin the resin R injection process into the mold 2 (step S3). In this case, it is sufficient to advance the screw 4 using the rated action; speed control of the screw 4 is not required. Injection begins, as... Figure 6 As shown by arrow D2, the plasticized and molten resin R in the heating cylinder 3 is filled into the cavity of the mold 2 through the injection nozzle 3n (step S4). Then, along with the filling of resin R, the injection pressure increases (step S5). Subsequently, if the injection pressure reaches the limiting pressure Ps, control is performed to maintain it at the limiting pressure Ps (injection pressure Pis), i.e., to prevent overshoot, thereby maintaining (limiting) the injection pressure at the limiting pressure Ps (step S6). Therefore, substantial pressure control is performed during the injection operation.

[0096] On the other hand, as the injection of resin R in step S3 begins, such as Figure 6 As shown, the resin R accumulated in front of the screw 4 is injected into the mold 2. Simultaneously, through the function of the partial backflow injection unit 5, a predetermined amount of backflow resin Rm, which becomes part of the resin R, gradually flows back towards the screw body 4m side behind the screw head 4s (step SN). That is, during injection, the screw 4 moves forward, and therefore the check valve 4sn moves to the rearward closed position due to the resin pressure in front. As a result, the resin passage 12 inside the check valve 4sn is cut off, but... Figure 6 As shown by arrow D3…, the recirculating resin Rm, which becomes part of the resin R accumulated in front of the screw head 4s, flows back to the screw body 4m side due to the injection pressure Pis through the gap between the outer peripheral surface of the conical front end 4sc of the screw head 4s and the inner peripheral surface of the heating cylinder 3, and then through the recirculation path 11 on the outer peripheral surface of the check valve part 4sn…

[0097] On the other hand, by filling the cavity of mold 2 with resin R, mold 2 is pressurized by resin R, creating a mold gap Lm between the fixed mold 2c and the movable mold 2m. Figure 7(Step S7). The mold clearance Lm is generated based on the preset molding clamping force Pc and molding injection pressure Pi (injection pressure Pis). In this case, if a preset injection time has elapsed since the start of injection, the injection filling of resin R relative to mold 2 is completed, and therefore the application of molding injection pressure Pi (injection pressure Pis) is stopped or reduced. Thus, the injection process is essentially completed, and therefore the reflow process also ends (Step S8).

[0098] Since the injection process (reflow) has ended, a plasticizing treatment of resin R is performed (step S9). In this case, a predetermined amount of reflowed resin Rm is mixed in front of the screw body 4m. That is, a portion of the reflowed resin Rm that has accumulated in front of the screw 4 after the first plasticizing treatment returns to the screw body 4m and is mixed in front of the screw body 4m. Therefore, a plasticizing treatment is performed on the resin R mixed with this reflowed resin Rm. Thus, even if insufficiently plasticized resin R accumulates in front of the screw 4, a replasticizing treatment is performed, thereby further promoting plasticization.

[0099] Furthermore, after the injection molding process is completed, resin R cures over time, and natural compression of resin R occurs during this curing (step S10). That is, since the volume decreases due to the curing of resin R, natural compression is performed by applying pressure based on the elastic recovery of mold 2 (especially movable mold 2m) to keep up with this volume reduction. Then, after a set cooling time, the mold closing cylinder 27 is driven by switching valve circuit 37 and controlling hydraulic pump 36, causing movable mold 2m to retract, thereby opening the mold and driving ejection cylinder 31 to eject the molded part attached to movable mold 2m (steps S11, S12). Thus, the molded part is removed, and one molding cycle ends. Afterwards, when continuing with the next molding, the same processes of mold closing, injection, and cooling are performed (steps S13, S2...).

[0100] Figure 8 This diagram shows a comparison of the standard deviations of the mold displacement when reflow is performed (with reflow) and when reflow is not performed (without reflow) in the injection molding method using the injection molding machine M of this embodiment (first embodiment). That is, Figure 8 This shows the process of molding 30 molded parts. Figure 7The deviation of the maximum value Lmp of the mold clearance Lm was measured. Thus, the standard deviation without backflow was 4.2 [μm], compared to 3.8 [μm] with backflow, representing an improvement of approximately 11 [%). This implies further improvement in the homogenization of the resin R after plasticizing, and a yield corresponding to this improvement was obtained for the finished product yield.

[0101] Therefore, according to this first embodiment of the injection molding machine M (injection molding method), as a basic structure (function), by moving the screw 4 housed in the heating cylinder 3 of the injection device Mi forward, resin R at the front of the screw head 4s at the front end of the screw 4 is injected and filled into the mold 2. At the same time, a predetermined amount of reflow resin Rm, which is part of the resin R, flows back to the screw body 4m side behind the screw head 4s through the reflow path 11 in the screw head 4s. Therefore, the yield of the final molded product can be greatly improved, and in particular, it can be provided as an injection molding machine that uses a new injection molding method that can further improve the yield of the previously so-called limit. As a result, it is possible to improve production efficiency and reduce production costs in the production of large molded products, special resin molded products, etc., and it can also effectively contribute to avoiding resource depletion and energy waste.

[0102] In particular, in the injection molding machine M (injection molding method) of the first embodiment, a clamping device Mc that can naturally compress the resin R along with the curing of the resin R in the mold 2 is used as the clamping device. A molding injection pressure Pi and a molding clamping force Pc that can produce a predetermined mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling are used to form qualified products. During molding, the clamping device Mc is clamped by the molding clamping force Pc, and the molding injection pressure Pi is set to a limiting pressure Ps to drive the injection device Mi to perform the injection filling of resin relative to the mold 2. Therefore, the injection molding method based on the injection molding machine M of the present invention can be applied to specific molding modes that do not have a metering process, that is, specific molding modes in which the state of the injection device Mi side is hardly affected, thereby achieving the above-mentioned improvement in production efficiency and reduction in production costs. Furthermore, from the viewpoint of helping to avoid the generation of resource depletion and the waste of energy consumption, it can be implemented as the best approach.

[0103] [Second Embodiment]

[0104] Next, refer to Figures 9-10 The structure of the partial reflux injection function unit 5 of the injection molding machine M in the second embodiment will be described.

[0105] Figure 9 yes Figure 1 The enlarged view of a portion of the injection device Mi in the injection molding machine M shown, namely the imaginary line circle A, shows a portion of the injection device Mi having the partial backflow injection function unit 5 of the second embodiment.

[0106] like Figure 9 As shown, the injection device Mi of the second embodiment is different from that of the first embodiment. Figure 2 The injection molding machine M shown has the same basic structure as the injection device Mi. In the second embodiment, when constructing the partial reflow injection function unit 5, by... Figure 1 The molding machine controller C shown is supplemented with a reversal control function Fc that reverses the screw 4, which facilitates the reflow and quantity control of the reflow resin Rm. Therefore, software for implementing the reversal control function Fc is stored in the program area 42mp of the internal memory 42m. When configuring the partial reflow injection function 5, if such a reversal control function Fc is provided, no changes to the shape of the screw 4 itself are required. Therefore, reflow can be achieved through the control of the screw 4, further simplifying implementation and improving versatility.

[0107] Furthermore, a reverse setting function Fcs is provided on the reverse control function Fc, which sets the period and rotational speed for reversing the screw 4. By providing such a reverse setting function Fcs, the recirculation rate of the reflow resin Rm can be set, thus allowing for easy setting of any recirculation rate and avoiding any impact on the original filling amount relative to the injection filling of the mold 2.

[0108] In this case, when setting the period and rotation speed for reversing the screw 4, it is preferable to set the period and rotation speed as follows: the screw 4 can be moved forward by the molding injection pressure Pi, and the resin R in front of the screw head 4s is injected into the mold 2. At the same time, a predetermined amount of reflow resin Rm, which is part of the resin R, i.e., an amount of reflow resin Rm selected in the range of 10-60% relative to the volume of the resin R injected into the mold 2, is reflowed to the screw body 4m side behind the screw head 4s through the resin passage 12 that becomes the inner side of the screw head 4s.

[0109] In addition, Figure 9 In the middle, to and Figure 1 and Figure 2 Identical parts are labeled with the same number to make the structure clear, and their detailed descriptions are omitted.

[0110] Next, refer to Figure 1 and Figure 10 ( Figure 4 The flowchart shown illustrates the molding steps of the injection molding method using the injection molding machine M of the second embodiment.

[0111] Figure 10 The flowchart shown illustrates Figure 4 The flowchart shown illustrates the specific processing steps in step SN, and the overall molding process follows these steps. Figure 4 The flowchart shown illustrates the process. That is, the injection molding method of the injection molding machine M in the second embodiment is used, with the same pre-settings as the specific molding mode in the first embodiment, and the specific processing steps during production are the same except... Figure 4 Except for the processing content of step SN shown, it is basically the same as steps S1-S11. Therefore, the following refers to... Figure 10 Only the processing portion of the second embodiment in step SN will be described in detail.

[0112] Now, let's plan to proceed. Figure 4 The state of step S3 in the flowchart shown. In step S3, the injection cylinder 24 of the injection device Mi is driven, thereby starting the injection process of resin R relative to the mold 2, and the resin R accumulated in front of the screw 4 is filled into the mold 2 (step S4).

[0113] On the other hand, at a predetermined time, such as the start of the injection process or after a predetermined set time, the screw 4 is reversed via the reverse control function unit Fc (step SN1). As a result, the screw 4 reverses in the direction of arrow Drn according to the rotational speed set by the reverse setting function unit Fcs. This promotes the backflow of a portion of the resin R accumulated in front of the screw head 4s to the screw body 4m (step SN2). That is, since the reverse rotation of the screw body 4m moves the resin R backward, a predetermined amount of backflow resin Rm, which is a portion of the resin R accumulated in front of the screw head 4s, flows back against the flow path 11… in the screw head 4s to the screw body 4m, thus promoting backflow.

[0114] Then, after the period (reflow time) set by the reverse setting function unit Fcs has elapsed, the reverse control is stopped (steps SN3, SN4). On the other hand, on the mold 2 side, if the mold gap Lm is generated by injection filling and the injection process is completed, the resin R is cured as time passes, and the resin R is naturally compressed along with the curing, etc., and the same processing (operation) as in the first embodiment is performed (steps S5, S6, S7...).

[0115] Therefore, according to the injection molding method using the injection molding machine M of the second embodiment, the same function as the first embodiment can be performed by the partial reflow injection function unit 5. Therefore, in addition to enjoying the same basic effect as the first embodiment, it can also enjoy the effect of promoting reflow, which is the same as the first embodiment.

[0116] in addition, Figure 11 The relationship between screw rotation and recirculation flow rate is shown when using the injection molding machine M of the second embodiment in an injection molding method. Thus, according to the second embodiment, the recirculation of the recirculated resin Rm can be promoted and its quantity controlled, thereby making the screw rotation proportional to the recirculation flow rate, and thus allowing arbitrary control of the recirculation flow rate.

[0117] Figure 12 and Figure 13 Variations of the first and second embodiments are shown. Figure 2 The first embodiment shown illustrates a screw head 4s using a cylindrical check valve section 4sn, but it could also use a screw head 4s. Figure 12 The spherical check valve section 4sn shown can be used with various shapes of check valve sections 4sn and screw heads 4s, and their structure and type are not limited. Furthermore, in Figure 12 In the diagram, 51 represents the resin pathway. Furthermore, in... Figure 12 In the middle, to and Figure 2 Identical structural and functional components are labeled with the same numbers to clarify the structure and omit detailed descriptions. Therefore, Figure 12 As a variation of the first embodiment, the basic structure of the injection molding machine M and the basic processing steps of the injection molding method are the same as those of the first embodiment described above.

[0118] In addition, even Figure 13 The screw head 4s shown does not have the check valve section 4sn. The injection molding machine M of the present invention can also be used, and the presence or absence of the check valve section 4sn is not limited. Furthermore, in Figure 13 In the text, 52 represents the spiral ridge. Furthermore, in... Figure 13 In the middle, to and Figure 9 Identical structural and functional parts are labeled with the same numbers to clarify the structure and omit detailed descriptions. Therefore, Figure 13 As a variation of the first or second embodiment, the basic structure of the injection molding machine M and the basic processing steps of the injection molding method are the same as those of the first or second embodiment described above.

[0119] [Third Embodiment]

[0120] Next, refer to Figures 14-22The structure of the injection molding machine M according to the third embodiment will be described. Furthermore, the third embodiment is an injection molding machine M according to the second aspect of the present invention.

[0121] The first or second embodiment, which includes the aforementioned variations, shows an injection molding machine M in which both the "injection process" and the "reflow process" are performed simultaneously, but the third embodiment shows an injection molding machine M in which only the "reflow process" is performed independently after the "injection process" is completed.

[0122] The third embodiment has a control function that controls the injection device Mi during molding in the molding machine controller C to sequentially execute the following steps: plasticizing step Wi1, in which the resin in the heating cylinder 3 is plasticized by rotating the screw 4 in the heating cylinder 3; injection step Wi2, after the plasticizing step Wi1 is completed, the screw 4 is moved forward to inject a portion of the plasticized resin R accumulated in front of the screw head 4s of the screw 4 into the mold 2; and plasticizing promotion step Wi3, after the injection step Wi2 is completed, a portion of the remaining plasticized resin R is returned as recirculated resin Rm to the rear of the screw head 4s.

[0123] Therefore, the molding machine controller C stores software for implementing the following functions: the function of recirculating the plasticized resin R after plasticization in the plasticizing promotion process Wi3, that is, the function of recirculating a portion of the resin R accumulated in front of the screw head 4s (recirculating resin Rm) back to the rear of the screw head 4s by additional control of the screw 4, specifically, the function of pressurizing control relative to the forward direction of the screw 4 or the function of reversing control of the screw 4.

[0124] In this case, the pressure control function is a backflow method that causes the resin R to flow backward by increasing the pressure relative to the forward direction of the screw 4. With the pressure control function, after the resin R in the mold 2 has fully cured (after the gate is sealed), or after the cooling process following the injection step Wi2, in a cured state that does not affect the molded part (resin) in the mold 2, the pressure of the resin R accumulated in front of the screw head 4s can be increased to the level required for backflow. Therefore, this can also be implemented by providing a small backflow path at the screw head 4s that does not cause backflow due to the molding injection pressure Pi, or by providing a backflow path with an opening and closing function. Therefore, the amount of backflowed resin (returned resin amount) can be easily controlled by increasing or decreasing the pressure and setting the pressure time.

[0125] On the other hand, the reverse control function is a recirculation method that returns resin R backward by reversing the screw 4. It essentially functions in conjunction with the aforementioned pressure control function. With the reverse control function, the recirculation flow rate can be adjusted by controlling the screw 4 to reverse. Therefore, the amount of recirculated resin can be set by selecting conditions such as the reversal period and rotation speed, making implementation easier. Furthermore, by changing the reversal period and rotation speed of the screw 4, any recirculation flow rate can be easily and accurately set. Additionally, either the pressure control function or the reverse control function can be used.

[0126] Next, refer to Figure 1 and Figures 14-20 The molding steps of the injection molding method using the injection molding machine M of the third embodiment will be described.

[0127] First, the aforementioned specific molding pattern is pre-set. Furthermore, the basic molding steps of this specific molding pattern are the same as those described in the aforementioned Patent Document 1 (International Publication No. WO2011 / 161899). That is, it can be performed in the same manner as in the first embodiment described above.

[0128] First, the injection pressure, which becomes the injection condition for the injection unit Mi, is initially set by the molding machine controller body 42c. This injection pressure can be set based on the capacity (driving force) of the injection unit Mi. Second, the clamping force, which becomes the clamping condition for the clamping unit Mc, is initially set by the molding machine controller body 42c. This clamping force can be set based on the capacity (driving force) of the clamping unit Mc.

[0129] Next, the molding injection pressure Pi used in production is determined by optimizing the initially set injection pressure, and the molding clamping force Pc used in production is determined by optimizing the initially set clamping force. The optimization of the clamping force and injection pressure can be performed as follows: First, a trial molding is conducted using the initially set clamping force and injection pressure. When the clamping force is set relatively high, burrs are not generated, and porosity, warping, and venting become undesirable or slightly undesirable. Then, the clamping force and injection pressure are varied in stages, and trial molding is performed at each stage. The size of the mold gap Lm between the fixed mold 2c and the movable mold 2m is obtained by a mold gap sensor (not shown, such as a reflective optical sensor), and displayed on the waveform display section of the screen 42d. The quality of the molded product is then observed.

[0130] exist Figure 14 The waveform display shows the variation data of the mold clearance Lm. Additionally, Figure 14The range (bands) of the maximum and minimum values ​​during 30 molding injections is shown. In this case, such as Figure 14 As shown, the basic change occurs after injection begins. At time t0, mold 2 starts to open, and at time tp, the maximum mold gap Lmp is generated. Afterward, it gradually closes, eventually stabilizing at the residual mold gap Lme.

[0131] Furthermore, the injection pressure can be optimized by setting the molding injection pressure Pi to the condition that the specified mold gap Lm (approximately 0.03-0.30 mm) is generated between the movable mold 2m and the fixed mold 2c during injection filling, and that qualified products can be formed. Specifically, by appropriately changing the injection pressure, the size before the resin R begins to abnormally fill the mold 2 can be selected. In addition, the determined molding injection pressure Pi is set as the limiting pressure Ps relative to the injection pressure during production. On the other hand, by changing the conditions and repeating these trial moldings, the clamping force that satisfies the above conditions can be selected. The selected clamping force is set as the molding clamping force Pc when the mold 2 is closed during production. In this case, the magnitude of the clamping force and the injection pressure can be arbitrarily set by the operator, or it can be determined automatically or semi-automatically using the automatic tuning function of the injection molding machine M.

[0132] Next, regarding the specific processing steps during production, please refer to the diagrams and follow the instructions. Figure 15 The process diagram shown and Figure 16 ( Figure 17 The flowchart shown is used for illustration.

[0133] During production, the resin (material) is first plasticized (step S21). This plasticizing process is called... Figure 15 The plasticizing process Wi1 is shown. In the plasticizing process Wi1, the metering motor 25 of the injection unit Mi is driven to rotate by the control of the hydraulic pump 36 and the switching of the valve circuit 37.

[0134] thus, Figure 9 The screw 4 shown rotates forward at a set speed and duration. Through the forward rotation of the screw 4, resin R is conveyed forward, thus the resin R on the screw body 4m side is plasticized and accumulates forward through the screw head 4s. At this time, the resin R moves forward from the screw body 4m side, thereby moving the check valve 4sn to its forward open position. Therefore, the resin R on the screw body 4m side reaches the front of the cone front end 4sc through the resin passage 12 inside the check valve 4sn and the resin passage 13 of the cone front end 4sc… As a result, the plasticized resin R gradually accumulates in the heating cylinder 3 in front of the cone front end 4sc, and the screw 4 moves backward along with this accumulation.

[0135] Furthermore, in certain molding modes, the precise metering process of resin R, as required in conventional molding methods, is not necessary. That is, in these specific molding modes, the injection process only requires injection until the resin R fills the cavity; therefore, the plasticizing process only requires that most of the resin R be plasticized. In other words, while the metering process, as in conventional metering, is performed, precise metering control to obtain accurate values ​​is not required.

[0136] Next, by controlling the hydraulic pump 36 and switching the valve circuit 37, the mold closing cylinder 27 of the mold closing device Mc is driven, causing the movable mold 2m to move in the mold closing direction (step S22). This action becomes... Figure 15 The mold closing process Wc1 is shown. Then, if mold 2 is fully closed, a mold closing process (step S23) is performed on mold 2 in such a way that the mold closing force becomes the set molding mold closing force Pc. This action becomes Figure 15 The mold closing process Wc2 is shown. Additionally... Figure 18 The status is shown.

[0137] Subsequently, by switching the valve circuit 37 and controlling the hydraulic pump 36, the injection cylinder 24 of the injection device Mi is driven to begin the injection process of resin R into the mold 2 (step S24). Thus, the process is performed... Figure 15 The injection process Wi2 is shown. In this case, the screw 4 only needs to advance by the rated action, and there is no need to control the speed and pressure of the screw 4. Due to the start of injection, the plasticized and molten resin R in the heating cylinder 3 is filled into the cavity of the mold 2 through the injection nozzle 3n (step S25).

[0138] Then, as resin R is filled, the injection pressure increases (step S26). Afterwards, if the injection pressure reaches the limit pressure Ps, control is performed to maintain the injection pressure at the limit pressure Ps, i.e., to prevent overshoot, thus maintaining (limiting) the injection pressure at the limit pressure Ps (step S27). Therefore, substantial pressure control is achieved during the injection operation.

[0139] Furthermore, by filling the cavity of mold 2 with resin R, mold 2 is pressurized by resin R, creating a pressure between the fixed mold 2c and the movable mold 2m, as shown in the image. Figure 14 The mold clearance Lm changes as shown (step S28). That is, proceed with... Figure 15 The natural clearance generation process Wc3 is shown. This mold clearance Lm is generated based on the preset molding clamping force Pc and molding injection pressure Pi. Figure 19This state is shown. Additionally, in this figure, an image showing the maximum mold gap Lmp is displayed, representing the mold gap Lm. Afterwards, if a preset injection time has elapsed since the start of injection, the injection filling of resin R relative to mold 2 is complete. That is, injection process Wi2 ends (step S29).

[0140] Additionally, the mold sides are transferred to cooling process Wc4, which involves cooling for a pre-set cooling time. In cooling process Wc4... Figure 15 In the process, as time passes, resin R is cured, and natural compression of resin R occurs along with this curing (steps S30, S31). That is, since the capacity decreases due to the curing of resin R, natural compression is performed by pressure based on the elastic recovery of mold 2 (especially movable mold 2m) in order to keep up with the decrease in capacity. Figure 20 This state is shown. Additionally, the figure shows an image of residual mold clearance Lme, which is produced as mold clearance Lm.

[0141] On the other hand, if injection step Wi2 is completed, execution will proceed according to the preset time. Figure 15 The plasticizing acceleration process Wi3 is shown (step S32). In this case, firstly, from the end time of injection process Wi2 or the start time of cooling process Wc4, auxiliary plasticizing treatment of the resin (material) is performed for a predetermined auxiliary plasticizing time T1 (step S121). The reason is that at the end of the injection process, the plasticized accumulated resin R in front of the screw 4 becomes a small amount, so the return flow is ensured by performing auxiliary plasticizing treatment for only auxiliary plasticizing time T1. In addition, the auxiliary plasticizing treatment can be the amount (total amount) in plasticizing process Wi1, or it can be a part of it. Furthermore, the set auxiliary plasticizing time T1 can also be set according to a predetermined auxiliary plasticizing position relative to the screw 4.

[0142] In addition, preferably, the auxiliary plasticizing process is set to the following lengths: the length at which the resin R in the mold 2 (including the gate, etc.) is cured to a certain extent, and even if a high forward pressure is applied to the screw 4 through the pressure control function, the resin R will not flow forward; or the length at which the resin R (molded article) in the mold 2 will not be affected even if the screw 4 is reversed through the reverse control function.

[0143] Then, if the auxiliary plasticizing process is completed, the actual plasticizing promotion process Wi3 is performed. That is, the aforementioned reverse control function and / or pressure control function for the screw 3 are executed (step S122). In this case, in the pressure control function, the injection cylinder 24 is driven and a forward pressure is applied to the screw 4. As mentioned before, the pressure at this time is set to be higher than the molding injection pressure Pi (limiting pressure Ps), so that it can flow backward. In addition, as mentioned above, the additional pressure begins at a moment when the resin R will not flow forward even if a higher forward pressure is applied, that is, at least through the start of the cooling process Wc4 ​​in the mold 2 to perform gate sealing, etc., in a state where the molded article (resin R) is not affected.

[0144] Therefore, the plasticized resin R accumulates and flows back to the rear of the screw head 4s through the gap between the screw head 4s and the heating cylinder 3. Furthermore, the backflowing resin Rm flowing counter-currently to the rear of the screw head 4s mixes with the resin R on the screw body 4m side. Afterwards, if the plasticizing acceleration treatment time T2 has elapsed, the plasticizing acceleration control (pressure control) is stopped (steps S123, S124). That is, the plasticizing acceleration process Wi3 using the pressure control function ends.

[0145] Therefore, from the viewpoint of ensuring production efficiency and yield, the plasticizing acceleration treatment time T2 and the pressure when using the pressure control function are preferably the end of the cooling treatment and a pressure higher than the injection pressure Pi. Furthermore, to make the pressure control function more effective, it is preferable to provide a small backflow path at the screw head 4s that does not cause backflow due to the molding injection pressure Pi, or a backflow path with an opening and closing function.

[0146] On the other hand, when the reverse control function is used, in addition to the pressurization control function, the metering motor 25 is driven to reverse the screw 4 according to a preset rotation speed (step S122). This promotes the backflow of the plasticizing accumulated resin R that has passed through the screw head 4s to the rear of the screw head 4s. Furthermore, the backflowing resin Rm that has passed through the screw head 4s is mixed with the resin R on the screw body 4m side behind the screw head 4s. Afterwards, if the plasticizing acceleration processing time T2 has elapsed, the plasticizing acceleration control (reverse control) is stopped (steps S123, S124). That is, the plasticizing acceleration process Wi3 using the reverse control function ends.

[0147] Therefore, from the perspective of ensuring production efficiency and yield, the plasticizing acceleration processing time T2 and the rotation speed of screw 4 when using the reverse control function are preferably performed at the highest possible speed after the cooling process is completed. Figure 20 This shows the state in which the screw 4 advances, causing the target return flow to flow back to the rear of the screw head 4s.

[0148] If the plasticizing facilitation step Wi3 is completed, a plasticizing treatment based on the plasticizing step Wi1 is performed (step S33). In this case, a portion of the recirculated resin Rm is mixed in front of the screw body 4m. That is, a portion of the resin R accumulated in front of the screw 4 after the so-called primary plasticizing treatment returns to the screw body 4m as recirculated resin Rm and is mixed in front of the screw body 4m. Therefore, a plasticizing treatment is performed on the resin R mixed with this recirculated resin Rm. Thus, even if insufficiently plasticized resin R and recirculated resin Rm accumulate in front of the screw 4, a replasticizing treatment is performed, thereby further promoting plasticizing.

[0149] On the other hand, Figure 16 In the process, on the clamping device Mc side, if the cooling process Wc4 ​​ends after the set cooling time, the clamping cylinder 27 is driven by the switching of valve circuit 37 and the control of hydraulic pump 36, causing the movable mold 2m to retract, thereby opening the mold (step S34). This step becomes... Figure 15 The mold opening process Wc5 is shown. Then, if the mold opening is complete, the ejection cylinder 31 is driven to eject the molded part attached to the movable mold 2m (step S35). This step becomes Figure 15 The molded part removal process Wc6 is shown. Thus, the molded part is removed, and one molding cycle ends. Therefore, when continuing the next molding process, the mold closing, mold closing, injection, cooling and other processes (steps S36, S22...) are performed in sequence.

[0150] Figure 14 The diagram illustrates the relationship between Lm (mm) and time t in injection step Wi2 of the injection molding method based on the injection molding machine M of the third embodiment. Specifically, it shows the variation data of the die gap Lm... when molding 30 molded articles, i.e., the range (bands) of the maximum and minimum values ​​in the 30 injections. The solid line band Bi indicates the case with backflow based on the injection molding machine M of the third embodiment, and the imaginary line band Br indicates the case without backflow. Thus, in the case of backflow, the deviation of the die gap Lm... is smaller, resulting in a more stable operation. Conversely, in the case without backflow, the deviation of the die gap Lm... is larger, resulting in a less stable operation. This means that the homogenization of the resin R after plasticizing is further improved, and a yield corresponding to this improvement is obtained regarding the yield of the molded articles.

[0151] Furthermore, the relationship between screw reversal and return flow rate in the injection molding method based on the injection molding machine M of the third embodiment is also as described above. Figure 11Similarly, if the injection molding machine M of the third embodiment is used, it is possible to promote the reflow of resin R and control its quantity, so that the screw reversal amount can be proportional to the reflow rate, thereby allowing arbitrary control of the reflow rate.

[0152] Next, refer to Figure 21 and Figure 22 The molding method of the injection molding machine M using a modified example of the third embodiment will be described.

[0153] This variation uses [a specific feature] Figure 22 The injection molding machine M (injection unit Mi) shows a flow-stop nozzle 61. The illustrated flow-stop nozzle 61 has a known construction, in Figure 22 In the middle, 37 represents Figure 1 The valve circuit shown is described as follows: 62 represents a shut-off valve that opens and closes the nozzle port 3ne at the front end of the injection nozzle 3n via the switching action of this valve circuit 37; 62v represents a shaft-shaped valve body; 62c represents a drive cylinder that moves the valve body 62v forward or backward in the opening direction (rear) or closing direction (forward); and 63 represents the resin passage. Furthermore, regarding the aforementioned... Figure 9 Identical parts are labeled with the same number to make the structure clear, and their detailed descriptions are omitted.

[0154] If such a flow-stopping nozzle 61 is used, the nozzle orifice 3ne can be closed as needed, thus allowing the plasticizing acceleration process Wi3 to be performed between the cooling process Wc4, the mold opening process Wc5, and the molded part removal process Wc6. As a result, sufficient plasticizing acceleration treatment can be performed in time, thereby enabling more reliable and efficient implementation of the injection molding method using the injection molding machine M of the present invention. Furthermore, although the use of a flow-stopping nozzle 61 is illustrated, various nozzle structures with the same function, such as valve nozzles, can be used instead.

[0155] Figure 21 This is a flowchart illustrating the processing steps of the injection molding method according to a modified embodiment, specifically showing... Figure 16 The flowchart shown illustrates step S32. Furthermore, the variant example, aside from the processing content of step S32, is basically based on... Figure 16 The same processing steps as shown in the flowchart are followed.

[0156] In a variation, the aforementioned process is pre-set. Figure 17 The process includes an auxiliary plasticizing treatment section and a plasticizing acceleration treatment section. In this case, the auxiliary plasticizing treatment section sets the unit time for auxiliary plasticizing treatment to a predetermined auxiliary plasticizing time T1e, and the plasticizing acceleration treatment section sets the unit time for plasticizing acceleration treatment to a predetermined plasticizing acceleration treatment time T2e.

[0157] Now, assuming Figure 16 ( Figure 21 The case where "step S29" ends is shown in the diagram. In a modified example, based on this, the shut-off valve 62 is driven and controlled to switch the valve 62 to the closed side (step S-SC). That is, in this case, the valve body 62v moves forward and the nozzle port 3ne is closed.

[0158] Next, the aforementioned process is performed within the auxiliary plasticizing time T1e. Figure 17 The auxiliary plasticizing process is performed in step S201. If the auxiliary plasticizing process ends after the auxiliary plasticizing time T1e, the plasticizing acceleration process, which performs plasticizing acceleration treatment during the plasticizing acceleration treatment time T2e, is then performed (steps S202, S203). Then, the combined process of the auxiliary plasticizing process and the plasticizing acceleration process is repeated a predetermined number of times N (steps S204, S201...).

[0159] This combined process can be achieved by using the flow-stopping nozzle 61 to ensure sufficient time for the plasticizing acceleration process Wi3. Therefore, it not only extends the processing time of the plasticizing acceleration process Wi3, but also allows this combined process to be repeated multiple times (N times). Furthermore, the number of repetitions can be arbitrarily set. Figure 21 The example illustrates the case of performing the combined process multiple times (N times), but it can also be repeated within the allowable time of the plasticizing acceleration process Wi3.

[0160] Therefore, in cases involving large molded products with long cooling times, such repeated processing allows for efficient use of the cooling time. This results in more uniform and dense plasticization of the resin R, which contributes to further improvements in the quality and yield of the molded products.

[0161] If the above plasticizing accelerator step Wi3 is completed, plasticizing treatment based on plasticizing step Wi1 is performed (step S33). Additionally, the shut-off valve 62 is driven and controlled at a predetermined time to switch the valve 62 to the open side (step S-S0). This open side position is called... Figure 22 The position shown. Afterwards, while continuing with the next molding process, the same sequence of processes (steps S36, S22, S23…) is performed (refer to…). Figure 16 )).

[0162] Therefore, according to the third embodiment of the injection molding machine M, which includes such a modification, the basic structure includes a plasticizing process Wi1 during molding, in which the screw 4 inside the heating cylinder 3 is rotated to plasticize the resin inside the heating cylinder 3; and an injection process Wi2, in which a portion of the plasticized accumulated resin R stored in front of the screw head 4s in the screw 4 is injected into the mold 2 by moving the screw 4 forward after the plasticizing process Wi1. In contrast, as a new process, a plasticizing promotion process Wi3 is added, in which a portion of the remaining plasticized accumulated resin R is returned as recirculating resin Rm to the rear of the screw head 4s after the injection process Wi2. Therefore, an injection molding machine M can be provided that can avoid adverse effects on the molded product and further improve the yield of the final molded product, especially the yield beyond the previously so-called limit, thus realizing a new injection molding method. As a result, it can improve production efficiency and reduce production costs in the production of large molded products and special resin molded products, and can also effectively contribute to avoiding resource depletion and energy waste.

[0163] In particular, as the mold clamping device Mc, a mold clamping device capable of naturally compressing the resin along with the curing of the resin within the mold 2 is used. The molding injection pressure Pi and the molding clamping force Pc capable of producing qualified products are predetermined and set to generate a predetermined mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling. During molding, the mold clamping device Mc is clamped by the molding clamping force Pc, and the molding injection pressure Pi is set to a limiting pressure Ps. Therefore, the injection molding machine of the present invention can be applied to specific molding modes where the state of the metering process without the injection device Mi side is hardly affected. Thus, it is possible to improve production efficiency and reduce production costs. Furthermore, from the viewpoint of helping to avoid resource depletion and energy waste, this can be implemented as the best approach.

[0164] The preferred embodiments (first embodiment to third embodiment) have been described in detail above. However, the present invention is not limited to such embodiments. In the details of the structure, shape, raw materials, quantity, value, method, etc., any changes, additions, or deletions can be made without departing from the spirit of the present invention.

[0165] For example, the preferred amount of reflow resin Rm is selected from a range of 10-60% relative to the volume of resin R injected into the mold 2, but any range can be selected depending on the type of resin R, the type of molded product, etc. Furthermore, when constructing the partial reflow injection function 5, an example is shown where at least one reflow path 11… is provided in the screw head 4s to reflow the reflow resin Rm. However, this concept is also included in the reflow path 11 when the outer diameter of the screw head 4s is selected to be slightly smaller, or the inner diameter of the heating cylinder 3 is increased, or a portion of the inner wall of the heating cylinder 3 is grooved. Additionally, the injection pressure additional setting function Fs is not a necessary element; for example, depending on the shape of the reflow path 11…, it is not necessary to provide the injection pressure additional setting function Fs. Furthermore, when a specified amount of reflow resin Rm is reflowed towards the screw body 4m, it can be through the inner side of the screw head 4s, through the outer periphery of the screw head 4s, or through both the inner and outer periphery of the screw head 4s. While this is optimal when using a specific molding mode, it can also be applied to injection molding machines M and injection molding methods using common molding modes. Additionally, the injection molding machine M can be a hydraulic injection molding machine or an electric injection molding machine, and its drive method is not limited.

[0166] On the other hand, in the implementation method, it is best to apply a specific molding mode. This specific molding mode uses a clamping device Mc that can at least naturally compress the resin along with the curing of the resin in the mold 2. The molding injection pressure Pi and the molding clamping force Pc that can produce a predetermined mold gap Lm between the movable mold 2m and the fixed mold 2c during injection filling are predetermined and set in advance. During molding, the clamping device Mc is closed by the molding clamping force Pc, and the molding injection pressure Pi is set to a limiting pressure Ps. However, this method can also be applied to injection molding machines M and injection molding methods using conventional molding modes. Furthermore, the injection molding machine M can be a hydraulic injection molding machine or an electric injection molding machine, and its drive method is not limited. Furthermore, in the plasticizing accelerator step Wi3, pressure control and reverse control functions are exemplified as functions for refluxing the plasticized accumulated resin R, but the possibility of refluxing it through other functions is not excluded, and the specific methods for making the pressure control and reverse control functions function are not limited to the methods of the respective examples, and other methods that can perform the same functions can also be used.

[0167] Industrial availability

[0168] This invention enables the use of various injection molding machines that inject resin into a mold after it has been closed by a specified clamping force at a specified injection pressure to perform molding.

Claims

1. An injection molding machine, comprising: A mold closing device that closes a mold consisting of a fixed mold and a movable mold using a specified mold closing force; An injection unit that injects filling resin into a mold after it has closed, using a specified injection pressure; and The molding machine controller controls the mold clamping device and the injection device. Its features are, The injection molding machine is equipped with a partial reflow injection function. When the screw, housed in the heating cylinder of the injection device, moves forward to inject resin from the front end of the screw head into the mold, and resin of a selected range of 10%-60% of its volume flows back as reflow resin to the screw body portion behind the screw head, the partial reflow injection function, while injecting resin from the front end of the screw head into the mold, simultaneously allows resin of a selected range of 10%-60% of its volume to flow back as reflow resin through the inner side and / or the outer peripheral side of the screw head to the screw body portion behind the screw head.

2. The injection molding machine according to claim 1, characterized in that, The partial reflux injection function is configured such that at least one reflux path for resin reflux is provided at the screw head.

3. The injection molding machine according to claim 2, characterized in that, The partial reflux injection function section is provided with an injection pressure additional setting function section, which sets the injection pressure during molding to a predetermined value higher than the injection pressure when the resin does not reflux, which is set when the partial reflux injection function section is not provided.

4. The injection molding machine according to claim 1, characterized in that, The partial reflux injection function is configured to include a reversal control function that reverses the screw.

5. The injection molding machine according to claim 4, characterized in that, The reverse control function unit is provided with a reverse setting function unit, which sets the period and rotation speed for reversing the screw.

6. The injection molding machine according to claim 1, characterized in that, As the mold clamping device, a mold clamping device is used that can at least naturally compress the resin along with the curing of the resin in the mold, and the molding machine controller has the following control functions: pre-determines and sets an injection pressure (hereinafter, molding injection pressure) that generates a predetermined mold gap between the movable mold and the fixed mold during injection filling and is capable of molding a qualified product, and a mold clamping force (hereinafter, molding clamping force) that is capable of molding a qualified product; during molding, the mold clamping device is closed by the molding clamping force, and the molding injection pressure is set to a limiting pressure, thereby driving the injection device to inject and fill the mold with resin.

7. An injection molding machine, comprising: A mold closing device that closes a mold consisting of a fixed mold and a movable mold using a specified mold closing force; An injection unit that injects filling resin into a mold after it has closed, using a specified injection pressure; and The molding machine controller controls the mold clamping device and the injection device. Its features are, The injection molding machine has a molding machine controller that, by moving the screw housed in the heating cylinder of the injection device forward to inject resin at the front of the screw head into the mold and causing a predetermined amount of resin, which is part of the resin, to flow back as recirculation resin to the screw body portion behind the screw head, the molding machine controller sequentially executes the following steps: The plasticizing process involves rotating a screw inside the heating cylinder to plasticize the resin within the cylinder. In the injection molding process, after the plasticizing process is completed, a portion of the plasticized resin accumulated in front of the screw head is injected into the mold by moving the screw forward; and In the plasticizing and accelerating process, after the injection molding process is completed, a portion of the remaining resin is recirculated as reflow resin to the rear of the screw head. As the mold clamping device, a mold clamping device is used that can at least naturally compress the resin along with the curing of the resin in the mold, and the molding machine controller has the following control functions: pre-determines and sets an injection pressure (hereinafter, molding injection pressure) that generates a predetermined mold gap between the movable mold and the fixed mold during injection filling and is capable of molding a qualified product, and a mold clamping force (hereinafter, molding clamping force) that is capable of molding a qualified product; during molding, the mold clamping device is closed by the molding clamping force, and the molding injection pressure is set to a limiting pressure, thereby driving the injection device to inject and fill the mold with resin.

8. The injection molding machine according to claim 7, characterized in that, The injection device has a flow-stop nozzle or a valve nozzle.

9. The injection molding machine according to claim 7, characterized in that, In the plasticizing process, the plasticized accumulated resin is recirculated by controlling the forward pressure of the screw.

10. The injection molding machine according to claim 7, characterized in that, In the plasticizing acceleration process, the plasticized accumulated resin is recirculated by reversing the screw.

11. The injection molding machine according to claim 7, characterized in that, In the plasticizing accelerator step, an auxiliary plasticizing process is performed to ensure the amount of refluxing resin before the actual plasticizing accelerator treatment is carried out.

12. The injection molding machine according to claim 11, characterized in that, In the plasticizing accelerator step, an auxiliary plasticizing treatment section and a plasticizing accelerator section are set up to perform the auxiliary plasticizing treatment. The combination of the auxiliary plasticizing treatment section and the plasticizing accelerator section is repeated according to a preset number of times N or within the allowable time of the plasticizing accelerator step.

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