JP5466486B2 - Molding method for injection molding machine - Google Patents

Description

  The present invention relates to a molding method of an injection molding machine having a measuring step of plasticizing and weighing a molding material made of resin pellets supplied into a heating cylinder by rotating a screw.

  Generally, there are a measuring step for plasticizing and weighing a molding material made of resin pellets supplied into a heating cylinder by rotating a screw, and an injection process for injecting and filling molten resin in the heating cylinder that has been plasticized and measured into a mold. A molding method of an injection molding machine is known. In this case, in the metering step, rice granular resin pellets (molding material) are supplied into the heating cylinder 2 from the hopper 12 of the injection molding machine M shown in FIG. As the screw 3 is rotated, it is transferred forward and gradually plasticized by the heating and kneading action of the heating cylinder 2 and the screw 3, and the plasticized molten resin is measured and accumulated in front of the screw 3.

  By the way, when molding is performed using a specific molding material as a resin pellet, such as a PCTA resin material manufactured by Eastman Chemical Co., which is a relatively new resin material, melting starts early in the measurement process, and the screw As a result of idling in the heating cylinder, there arises a problem that measurement is impossible. That is, when a specific molding material such as a PCTA resin material is used, the molding material has a thermal effect on the side of the heating cylinder 2 immediately after dropping into the drop hole 13 directly below the hopper 12 (about 40 to 80 [° C.]). In response, the surface of the resin pellets Pe ... starts to melt at the position F3 shown in FIG. As a result, at the same F3 position, as shown in FIG. 9A, a phenomenon occurs in which the resin pellets Pe... Adhere to each other, and the screw flight 3f enters about 1 pitch forward from the drop hole 13 as shown in FIG. At the F4 position, as shown in FIG. 9 (b), the melting of the surface proceeds considerably, and the screw flight 3f... And in the F6 position shown in FIG. 3, it will be in the state almost integrated like FIG.9 (c). As a result, after molding is started, weighing is performed for about 10 to 20 shots. Thereafter, even if the screw 3 rotates, the molding material Pe ... in the drop hole 13 is also heated by the screw flight 3f ... No longer bite into 2. That is, the molding material Pe is difficult to be fed forward from the drop hole 13 and cannot be measured. For such a specific resin material, it is sufficient to design a dedicated molding machine that matches the resin characteristics. However, since it is impossible to mold other resin materials, an existing injection molding machine is used. It is desirable to enable molding.

  Conventionally, injection molding machines disclosed in Patent Documents 1 and 2 are known as injection molding machines that can meet such requirements. In Patent Document 1, the base temperature of an injection screw is relatively lowered. In order to ensure the transfer of the resin during weighing, a water jacket for adjusting the temperature of the cylinder base is provided on the outer periphery of the resin sampling port of the injection cylinder, and the injection screw base is provided behind the water jacket. A part of an injection molding machine provided with a water jacket for adjusting the temperature of an injection screw provided with a hole to be fitted to the outer peripheral surface is disclosed, and in Patent Document 2, a material biting failure is eliminated, plasticization of resin and For the purpose of stable measurement, the rear end of the effective screw length is divided into a supply section, a compression section, and a measurement section in order. An injection screw in which flights are continuously formed, wherein the ratio of the screw outer diameter D and the supply portion screw groove depth hf is hf / D = 0.14 to 0.17, and the space between the screw flight rear surface and the screw groove bottom surface The ratio of the curvature radius R of the screw portion to the supply portion screw groove depth hf is R / hf = 1.47 to 2.1, the curvature radius r between the screw flight front surface and the screw groove bottom surface, and the supply portion screw. A part of an injection molding machine including an injection screw in which a ratio to the groove depth hf is set to r / hf = 0.63 to 0.88 is disclosed.

JP 9-48053 A JP 2006-88533 A

  However, the conventional injection molding machine described above has the following problems to be solved.

  First, in the case of Patent Document 1, an additional temperature control device including a water jacket is required, and in the case of Patent Document 2, an additional screw that has been redesigned is required and cannot be ignored in terms of cost. Components are required. Therefore, in implementation, the cost increases due to the additional components, and it is difficult to change the additional components because they are fixed elements, and may not be compatible with other resin materials. There are difficulties.

  Second, even if a certain purpose is achieved for an existing resin material, it is not necessarily an effective countermeasure for solving the problem for a specific resin material such as the PCTA resin material described above. In other words, in order to solve the inherent problem of being impossible to measure which occurs when molding with a specific resin material, as in Patent Document 1, even if the base temperature of the injection screw is relatively low, heating is performed. The temperature distribution and the like that prevent adverse effects on the cylinder side cannot be easily set, and even if optimization is performed on other resin materials other than the specific molding material as in Patent Document 2, the specific resin is not necessarily used. It is not an effective countermeasure for materials.

  An object of the present invention is to provide a molding method of an injection molding machine that solves the problems existing in the background art.

  In order to solve the above-described problems, the molding method of the injection molding machine M according to the present invention comprises a weighing step S1c for plasticizing and weighing a molding material made of resin pellets supplied into the heating cylinder 2 by the rotation of the screw 3, and a plastic step A molding method having an injection step S3c for injecting and filling molten resin in the heating cylinder 2 into the mold 4 and performing the molding with a specific molding material Pe ..., the metering step from the end of the injection step S3c Between the start of S1c, by rotating the screw 3 by a predetermined angle Rr in the opposite direction to the rotation direction during weighing, the opposite behavior of the weighing step S1c with respect to the molding material Pe ... in the heating cylinder 2 It is characterized by carrying out a lump process S10c (S10ce) for applying the above.

  In this case, according to a preferred embodiment of the invention, the specific molding material Pe ... has at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [° C.] or less. Can be included. The predetermined angle Rr can be selected from 0.25 to 4 rotations.

  On the other hand, the molding method of the injection molding machine M according to another embodiment of the present invention plasticizes and measures the molding material by the resin pellets supplied into the heating cylinder 2 by the rotation of the screw 3 in order to solve the above-described problems. A molding method having a measuring step S1c and an injection step S3c for injecting and filling the molten resin in the heating cylinder 2 subjected to plasticization and weighing into the mold 4, and when performing molding with a specific molding material Pe ... The measurement time Tmd from the start of measurement to the end of measurement in S1c is monitored. When the measurement time Tmd exceeds the set measurement abnormality determination time Tms, the screw 3 is measured between the injection process S3c and the measurement process S1c. In the opposite direction to the rotation direction, the blocker gives the opposite behavior of the weighing step S3c to the molding material Pe ... in the heating cylinder 2 by rotating it by a predetermined angle Rr. Characterized in that to perform the S10c (S10ce).

  In this case, according to a preferred embodiment of the invention, the specific molding material Pe ... has at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [° C.] or less. Can be included. In addition, a basic angle Rro is set in advance with respect to the predetermined angle Rr, and when the measurement time Tmd first exceeds the measurement abnormality determination time Tms, the lump process S10c (S10ce) is performed for the basic angle Rro. If the measurement time Tmd exceeds the measurement abnormality determination time Tms, the lump process S10c (S10ce) can be performed at a predetermined angle Rr that is sequentially increased from the basic angle Rro each time the measurement time Tmd exceeds the measurement abnormality determination time Tms. At this time, if the limit angle RL is set in advance with respect to the predetermined angle Rr, and the predetermined angle Rr exceeds the limit angle RL, abnormality processing can be performed. Furthermore, the condition for determining that the measurement abnormality determination time Tms has been exceeded can be a condition that the measurement abnormality determination time N has been continuously exceeded. Further, the injection process S3c and the weighing process S1c can include a period between the end of the injection process S3c and the start of the measurement process S1c, or a period between the end of the measurement process S1c and the start of the injection process S3c.

  On the other hand, the molding method of the injection molding machine M according to another embodiment of the present invention plasticizes and measures the molding material by the resin pellets supplied into the heating cylinder 2 by rotating the screw 3 in order to solve the above-described problems. A molding method having a measuring step S1c and an injection step S3c for injecting and filling the molten resin in the heating cylinder 2 plasticized and metered into the mold 4, and when performing molding with a specific molding material Pe ... The cooling time Tcd of the molded product after S3c is finished is monitored, and when the continuous cooling time Tcd exceeds the set cooling limit judgment time Tcs, the screw 3 is moved in the direction opposite to the rotation direction during measurement. , By performing a lump process S10c that gives the opposite behavior of the weighing process S1c to the molding material Pe ... in the heating cylinder 2 by rotating it by a predetermined angle Rr. That.

  In this case, according to a preferred embodiment of the invention, the specific molding material Pe ... has at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [° C.] or less. Can be included. Further, if necessary, a return step S10cr for returning the screw 3 to the angle at the start of the split step S10c can be performed after the end of the split step S10c.

  According to the molding method of the injection molding machine M according to the present invention by such a technique, the following remarkable effects can be obtained.

  (1) When performing molding with a specific molding material Pe ..., by rotating the screw 3 by a predetermined angle Rr in the opposite direction to the rotation direction during measurement between the injection process S3c and the measurement process S1c. Since the splitting step S10c (S10ce) for imparting the opposite behavior of the weighing step S1c to the molding material Pe ... in the heating cylinder 2 is performed, it is possible to return the stuck molding materials Pe ... in a direction to separate them. it can. That is, when the molding material Pe ... is transferred into the heating cylinder 2 by screw flight, it is gradually compressed in the direction of rotation according to the rotation of the screw 3, but a lump process S10c imparting the opposite behavior of the weighing process S1c. By performing (S10ce), the stuck molding material Pe is returned to the direction in which they are separated by releasing the compressed state and applying rotation in the separating direction. As a result, the molding material Pe ... easily penetrates into the heating cylinder 2, and even when a specific molding material Pe ... that is easy to melt at a relatively low temperature is molded, the screw 3 is idled in the weighing step S1c. , Can solve the problem of weighing out.

  (2) When performing the lump process S10c (S10ce), the screw 3 is rotated by a predetermined angle Rr in the opposite direction to the rotation direction during measurement between the injection process S3c and the measurement process S1c. Therefore, it can be easily implemented by changing software (control program) without additional components. Therefore, the implementation can be facilitated and the cost can be reduced, and since there is no change such as addition of a fixing element, there is no possibility of adversely affecting the molding of other resin materials, and versatility and stability. Excellent (reliability).

  (3) The measurement time Tmd from the start of measurement to the end of measurement in the measurement step S1c is monitored, and when the measurement time Tmd exceeds the set measurement abnormality determination time Tms, the minute is measured between the injection step S3c and the measurement step S1c. If the lump process S10c (S10ce) is performed, the determination can be made based on the actual measurement time Tmd, so that even if the resin characteristics of the specific molding material Pe ... are unknown, the problem that the measurement becomes impossible is surely solved. And the effectiveness of the shaping | molding method concerning this invention can be enjoyed.

  (4) If the cooling time Tcd of the molded product is monitored, and when the continuous cooling time Tcd exceeds the set cooling limit judgment time Tcs, the lump step S10c is performed, the surface of the molding material Pe ... Since it is possible to stop the progress of the adhesion between the melting and the molding material Pe ..., even when the cooling time Tcd of the molded product becomes long, the problem that the measurement becomes impossible is surely eliminated, and the molding method according to the present invention is effective. Enjoy the sex.

  (5) Between the end of the injection step S3c and the start of the measuring step S1c, the screw 3 is rotated by a predetermined angle Rr in the opposite direction to the rotating direction at the time of measuring, thereby forming the molding material Pe in the heating cylinder 2 Since the lump process S10c (S10ce) that gives the opposite behavior to the weighing process S1c is performed on the ..., the conditions such as the waiting time of the cooling time between the end of the injection process S3c and the start of the weighing process S1c are taken into consideration And the optimal timing at the time of performing the lump process S10c or 10ce can be selected.

  (6) According to a preferred embodiment, at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [° C.] or less is included in a specific molding material Pe. For example, these specific molding materials Pe having unique resin characteristics are suitable from the viewpoint of eliminating the problem of incapability of metering, and reliable and stable metering and further molding can be performed.

  (7) According to a preferred aspect, if the predetermined angle Rr is selected from 0.25 to 4 rotations, the optimization can be achieved from the viewpoint of ensuring the effectiveness of the lump process S10c (S10ce).

  (8) According to a preferred embodiment, a basic angle Rro is set in advance with respect to a predetermined angle Rr. If the measurement time Tmd first exceeds the measurement abnormality determination time Tms, the lump process S10c (S10ce) is performed by the basic angle Rro. After this, if the weighing time Tmd exceeds the weighing abnormality determination time Tms, every time the weighing time Tmd exceeds the basic angle Rro, the block process S10c (S10ce) is performed at a predetermined angle Rr. The effectiveness of the lump process S10c (S10ce) can be reliably ensured.

  (9) If the limit angle RL is set in advance with respect to the predetermined angle Rr and the abnormal process is performed when the predetermined angle Rr exceeds the limit angle RL according to a preferred aspect, the block process S10c (S10ce) can avoid the influence on the molding quality, and before the molding failure occurs, perform abnormal processing such as stopping the molding operation or issuing an abnormal alarm, and take necessary countermeasures. Can be taken.

  (10) According to a preferred aspect, if the condition for determining that the measurement abnormality determination time Tms has been exceeded is a condition that the measurement abnormality determination time N has been exceeded, the noise that temporarily exceeds the measurement abnormality determination time Tms Therefore, only when the measurement time Tmd substantially exceeds the measurement abnormality determination time Tms can be reliably detected.

  (11) If the return step S10cr for returning the screw 3 to the angle at the start of the bundling step S10c is performed according to a preferred embodiment, the cooling time Tcd is particularly long. Thus, even if the number of times of the lump process S10c is increased, the influence on the molten resin (measured value) after measurement that may be generated by the lump process S10c can be offset.

The flowchart for demonstrating the process sequence of the shaping | molding method which concerns on suitable embodiment of this invention, The block diagram including the hydraulic drive part of the injection molding machine which implements the molding method, A side view showing a cross section near the hopper of the injection molding machine, Graph of weighing time against shot order when the molding method is implemented, Explanatory drawing of the timing of performing the lump process in the molding method, Graph of weighing time against shot order with the angle of screw rotation during the bundling process as a parameter, Explanatory drawing of the timing which performs the lump process and the return process in the shaping | molding method which concerns on the modified embodiment of this invention, Graph of metering time against shot order with continuous cooling time as a parameter in the cooling process, A photo of the weighing of a specific molding material to illustrate the challenges of the background art,

  Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.

  First, the configuration of an injection molding machine M that can perform the molding method according to the present embodiment will be described with reference to FIGS. 2 and 3.

  FIG. 2 shows the overall configuration of the injection molding machine M. The injection molding machine M includes an injection device Mi and a mold clamping device Mc. The injection device Mi includes a heating cylinder 2, and the heating cylinder 2 has an injection nozzle 11 at the tip and a hopper 12 at the rear. The lower end of the hopper 12 communicates with the inside of the heating cylinder 2 through the drop hole 13. Reference numerals 14... Denote heaters mounted on the outer peripheral surfaces of the heating cylinder 2 and the injection nozzle 11. The heating cylinder 2 is loaded with a screw 3, and the rear end of the heating cylinder 2 is provided with an injection cylinder 15 that drives the screw 3 forward and backward, and a metering motor (oil motor) 16 that rotates the screw 3. . On the other hand, the mold clamping device Mc includes a stationary platen 17 and a movable platen 18 that support the mold 4, and a mold clamping cylinder 19 that performs mold opening / closing and mold clamping with respect to the mold 4 by driving the movable platen 18 forward and backward. Is provided. As other actuators, although not shown in the drawings, a projecting cylinder for projecting a molded product in the mold 4, an injection apparatus moving cylinder for performing nozzle touch on the mold 4 or releasing it by moving the injection apparatus Mi forward and backward, etc. I have.

  On the other hand, 21 is a hydraulic drive unit, which includes a hydraulic pump 22 using a variable discharge hydraulic pump as a hydraulic drive source and a hydraulic panel 23 provided with various switching valves. The hydraulic pump 22 is driven to rotate by a servo motor 24, and the rotation speed of the servo motor 24 is detected by a rotary encoder 25 attached to the servo motor 24. Reference numeral 26 denotes an oil tank.

  Moreover, the molding machine controller 31 having a computer function for controlling the entire injection molding machine M is provided, and the molding machine controller 31 stores a control program 31p for executing the molding method according to the present embodiment. The molding machine controller 31 has a built-in servo circuit connected to the servo motor 24 described above. As a result, the number of rotations of the servo motor 24 can be variably controlled, and the discharge flow rate and discharge pressure of the hydraulic pump 22 can be variably controlled. Therefore, the drive control of the cylinders 15, 19. The operation process can be driven and controlled. A position sensor 32 detects the position of the screw 3 (screw position) and is connected to the molding machine controller 31.

  On the other hand, a display 33 is connected to the molding machine controller 31. A touch panel 33p is attached to the display 33, and various settings and the like can be performed by the touch panel 33p. Therefore, the display 33 provided with the touch panel 33p constitutes the setting unit 34. The setting unit 34 can set the measurement abnormality determination time Tms, the cooling limit determination time Tcs, and the like used for carrying out the forming method according to the present embodiment. The molding machine controller 31 is connected to the hydraulic panel 23 via a built-in sequence controller, and includes a sensor group including various sensors such as a pressure sensor and a temperature sensor for detecting the operation state of the injection molding machine M, and a servo motor. A rotary encoder 25 attached to 24 is connected to an input port of the molding machine controller 31. Further, the molding machine controller 31 is connected to the heaters 14 through built-in heater drivers.

  Next, the principle of the molding method according to this embodiment using the injection molding machine M will be described with reference to FIG.

  As described above, when molding is performed using a relatively new resin material such as PCTA resin material (specific resin material Pe ...) manufactured by Eastman Chemical Co., as a resin pellet, There is a problem in that it becomes idle in the heating cylinder 2 and becomes virtually impossible to measure. That is, when a specific molding material Pe ... such as a PCTA resin material is used, the molding material Pe ... has a thermal effect on the side of the heating cylinder 2 immediately after dropping into the drop hole 13 directly below the hopper 12 (40-80 [ In addition, the resin pellets (molding material Pe ...) stick to each other, and immediately after being transferred by the screw 3, the screw flight 3f ... It becomes clogged. As a result, after molding is started, weighing is performed for about 10 to 20 shots. Thereafter, even if the screw flight 3f of the screw 3 rotates, the molding material Pe ... in the drop hole 13 is heated. No longer bite into 2. That is, the molding material Pe is difficult to be fed forward from the drop hole 13 and cannot be measured.

  Thus, when molding a specific molding material Pe ... such as a PCTA resin material that is easily melted at a relatively low temperature, the melting of the surface starts at an earlier stage than a normal resin material, and the molding materials Pe ... By sticking to each other, the rotation of the screw flight 3 f. Therefore, since it is considered effective to return the stuck molding materials Pe... To each other again, the effectiveness was verified by rotating the screw 3 in the direction opposite to that during measurement. That is, in the measuring step, the molding material Pe is compressed in the rotational direction by the rotation of the screw 3, so that the screw 3 is rotated by a predetermined angle Rr in the opposite direction to the measuring direction before it becomes squeezed. Since it is considered that if the compressed molding material Pe... Is given a behavior opposite to that at the time of measurement, the molding materials Pe.

  FIG. 6 shows a change in the measurement time Tmd [seconds] with respect to the shot order with the angle Rr for rotating the screw 3 in the direction opposite to that when measuring when a specific molding material Pe is measured. In this case, a PCTA resin material (AN014 (product number) manufactured by Eastman Chemical Co., Ltd.) having a resin characteristic of starting melting at a temperature of 100 [° C.] or less is used as the specific molding material Pe. The temperature inside was set to 40 ° C. In FIG. 6, R90 indicates that when the screw 3 is rotated 90 [deg.] In the opposite direction to the time of measurement before starting the measurement of each shot, R180 indicates that the screw 3 is rotated 180 [[deg.] In the same direction before the measurement of each shot is started. When rotated, R360 does not rotate the screw 3 in the same direction before starting the measurement of each shot when R3 rotates the screw 3 360 ° in the same direction before the start of measuring each shot. Each case is shown.

  As is apparent from FIG. 6, in the case of Rn, even if measurement is possible from the start of molding (shot) to about 9 shots, thereafter, the measurement time Tmd is suddenly increased and measurement is impossible. In addition, the measurement time Tmd when the measurement is normally performed is about 2.5 to 3 [seconds] from FIG. Further, in the case of R90, even if the measurement can be performed up to about 22 shots from the start of molding, the measurement time Tmd is suddenly extended thereafter, and the measurement becomes impossible. On the other hand, in the case of R180 and R360, it is possible to measure even after exceeding 80 shots from the start of molding.

  As a result, if the screw 3 is rotated by a predetermined angle Rr, that is, in the example, 180 [°] or more in the opposite direction to the rotating direction during measurement for each shot, the molding material Pe. Even when molding a specific molding material Pe, which can be regenerated to be able to bite into the heating cylinder 2 and is easily melted at a relatively low temperature, the idle rotation of the screw 3 generated in the heating cylinder 2 is avoided. This eliminates the problem of being unable to measure.

  Next, a specific forming method according to the present embodiment will be described according to the flowchart shown in FIG. 1 with reference to FIGS.

  First, necessary setting is performed using the setting unit 34. The specific resin material Pe used is the same PCTA resin material as the resin material Pe used in the experiment of FIG. 6, the heating temperature of the heating cylinder 2 is 240 ° C., and the temperature in the drop hole 13 is 40 [° C.]. The main setting items are as follows.

  (A) A measurement abnormality determination time Tms for determining the presence or absence of abnormality with respect to the length of the measurement time Tmd from the start of measurement to the end of measurement is set. In the case of the example (FIG. 6), since the normal measurement time Tmd is about 2.5 to 3 [seconds], the measurement abnormality determination time Tms is set to 5 [seconds].

  (B) Since the condition for determining that the measurement abnormality determination time Tms has been exceeded is that the measurement abnormality determination time Tms has been continuously exceeded by the determination number N, this determination number N is set. In the case of illustration, it was set to 2 times.

  (C) A predetermined angle Rr for rotating the screw 3 in the opposite direction to the rotating direction during measurement is set. In the example, 180 [°] is set as the initial value of the predetermined angle Rr, that is, the basic angle Rro. Further, the predetermined angle Rr is sequentially increased from the basic angle Rro every time the measurement abnormality determination time Tms is exceeded. In this case, an addition value (for example, 180 [°]) is set, and the basic angle Rro (180 [°]) is sequentially added in increments of 180 [°]. The method of sequentially increasing the predetermined angle Rr is arbitrary. For example, the addition value may be a different value every time the addition is performed, or a coefficient with respect to the basic angle Rro or the predetermined angle Rr in use. A method of multiplying by may be used. The size of the basic angle Rro can be selected arbitrarily, but it is 0.25 to 2 rotations (90 to 720 [°]) from the viewpoint of ensuring a certain effect and avoiding unnecessary influence on the measurement value and the like. It is desirable to select the range, and in particular, to optimize it from the viewpoint of ensuring the effectiveness of the subsequent block process.

  (D) A limit angle RL with respect to the predetermined angle Rr is set. In the example, 4 rotations are set, and if the limit angle RL (4 rotations) is exceeded, an abnormal process is performed. Thereby, it is possible to avoid the influence on the molding quality associated with performing the block process described later, before performing the abnormal processing such as stopping the molding operation or issuing an abnormal alarm before molding failure occurs, Necessary measures can be taken.

  (E) The timing for rotating the screw 3 by an angle Rr in the opposite direction to the time of measurement is set. This timing can be selected between the injection step S3 and the weighing step S1, that is, between the end of the injection step S3 and the start of the weighing step S1, or between the end of the weighing step S1 and the start of the injection step S3. In the case of illustration, the timing between the end of the injection step S3 and the start of the weighing step S1 was selected.

  Hereinafter, a specific forming procedure will be described. First, a specific resin material Pe is put into the hopper 12. The specific resin material Pe ... is a resin pellet having a grain shape using a PCTA resin material as a raw material. Then, the molding machine controller 31 switches the hydraulic panel 23 and controls the servo motor 24 to perform a metering process for rotating the oil motor 16 at the rotational speed set in the rotational direction during metering (step S1). At this time, a predetermined back pressure is applied to the rear oil chamber of the injection cylinder 15. Next, when the metering step S1 is completed, the molding machine controller 31 switches the hydraulic panel 23 and controls the servo motor 24 to perform an injection step of advancing the piston of the injection cylinder 15 at the set injection speed (step) S2, S3).

  On the other hand, the molding machine controller 31 takes in the measuring time Tmd that is the time from the start of measurement to the end of measurement at the stage where the above-described measurement process S1 is completed (steps S2 and S4). Therefore, the molding machine controller 31 has a timer function for detecting the time from the start of measurement to the end of measurement. Further, the molding machine controller 31 determines whether or not the taken measurement time Tmd exceeds a preset measurement abnormality determination time Tms (step S5). At this time, if the measurement time Tmd does not exceed the measurement abnormality determination time Tms, the count number described below is reset, and the shot determination process is terminated. On the other hand, when the measurement time Tmd exceeds the measurement abnormality determination time Tms, 1 is counted as the abnormality determination, and this shot determination process is terminated. Then, when the count number becomes 2 by the count, the number of times that has been continuously exceeded reaches 2, that is, the predetermined number of determination times 2, so that a block command is output based on this (step S6). , S7). If a block command is output, the count is reset.

  On the other hand, when the above-described block command is not output when the injection process is completed, the molding for one shot is completed through subsequent processes such as the cooling process of the molded product (steps S8 and S9). ). On the other hand, when the above-described block command is output when the injection process is finished, the block process, that is, the molding machine controller 31 switches the hydraulic panel 23 and controls the servo motor 24. Thus, a lump process is performed in which the oil motor 16 is rotated at a set speed in a direction opposite to the rotation direction during measurement (steps S8, S9, S10). In this case, the angle Rr for rotating the screw 3 in the opposite direction is 180 [°] set in advance. Moreover, the rotation speed at the time of measurement can be used as the set speed for rotation, but this rotation speed can be arbitrarily set. Furthermore, when performing the lump process S10, the molding machine controller 31 performs position control for fixing the position of the screw 3 in the front-rear direction.

If there is a next molding, the same molding process (molding cycle) is repeated thereafter (steps S11, S1,...). In this case, after the bundling process is performed, the shot in which the measurement time Tmd does not exceed the measurement abnormality determination time Tms continues normally. However, the measurement time Tmd is again measured depending on various environments. The abnormality determination time Tms may be exceeded (steps S4, S5, S6). In this case, 180 [°] set as an addition value is added to the basic angle Rro (180 [°]), and thereafter, the predetermined angle Rr is changed to 360 [°] to perform the block process. (Steps S6 and S7). Therefore, after that, when the measurement time Tmd exceeds the measurement abnormality determination time Tms, 180 [°] as an addition value is added to 360 [°], and the predetermined angle Rr is set to 540 [°. ] The changed block process is performed (steps S6 and S7). As described above, when the measurement time Tmd exceeds the measurement abnormality determination time Tms, the bundling process is performed at a predetermined angle Rr that is sequentially increased from the basic angle Rro. Thereby, the effectiveness of a lump process can be ensured reliably.

  On the other hand, if the predetermined angle Rr becomes larger and exceeds a preset limit angle RL, an abnormal process such as stopping the molding operation or issuing an abnormal alarm is performed (steps S12 and S13). As described above, if the limit angle RL is set in advance with respect to the predetermined angle Rr, and if the predetermined angle Rr exceeds the limit angle RL, an abnormal process is performed, it is accompanied by performing the block process. There is an advantage that the influence on the molding quality can be avoided and necessary countermeasures can be taken before molding defects occur.

  In FIG. 4, the change of the measurement time with respect to shot order at the time of implementing the shaping | molding method which concerns on this embodiment is shown. As can be seen from the figure, the measurement time Tmd from the first shot to the seventh shot does not exceed the measurement abnormality determination time Tms, but the measurement time Tmd of the eighth shot and the ninth shot is continuous. Thus, the measurement abnormality determination time Tms is exceeded. Accordingly, when the ninth shot is completed, the count number is 2, that is, the number of times that the number is continuously exceeded is the determination number 2, so that a block command is output. Thereby, the lump process is performed for every shot from the next shot.

  In FIG. 4, in the 10th shot, the weighing time Tmd does not exceed the measurement abnormality determination time Tms due to the bundling process, but in the 11th shot, the measurement time Tmd is again determined as the measurement abnormality. Time Tms is exceeded. However, in the twelfth shot, since the measurement time Tmd does not exceed the measurement abnormality determination time Tms again, the behavior of the eleventh shot does not reach the number of determinations of 2, so it is determined as a temporary variation. In the example, after the 13th shot, stable weighing is performed without the weighing time Tmd exceeding the weighing abnormality determination time Tms. As described above, if the condition for determining that the measurement abnormality determination time Tms has been exceeded is that the predetermined determination number N has been exceeded, a noisy element that temporarily exceeds the measurement abnormality determination time Tms can be obtained. There is an advantage that only when the weighing time Tmd substantially exceeds the weighing abnormality determination time Tms can be reliably detected.

  FIG. 5 shows the timing for performing the lump process S10c (S10ce) in the molding method according to the present embodiment. In the embodiment of FIG. 1, as the timing of performing the lump process S10c, the case where it is performed between the end of the injection process S3c and the start of the weighing process S1c is shown. However, as in the lump process S10ce illustrated in FIG. It may be performed between the end of S3c and the start of the injection step S3c. Regardless of the timing, the same effect is exhibited in that the segmentation step S10c (S10ce) can be inserted before a certain time elapses with respect to the state in which the surface of the specific resin material Pe. Thus, since it can be applied between the end of the injection step S3c and the start of the weighing step S1c, or between the end of the measurement step S1c and the start of the injection step S3c, the interval between the end of the injection step S3c and the start of the measurement step S1c. In consideration of the cooling time or the waiting time between the end of the weighing step S1c and the start of the injection step S3c, it is possible to select the optimum timing when performing the lump step S10c.

  Therefore, according to such a molding method according to the present embodiment, when molding is performed using a specific molding material Pe ..., the screw 3 is moved between the injection step S3c and the weighing step S1c with respect to the rotation direction during weighing. In the opposite direction, by rotating by a predetermined angle Rr, the lump process S10c that gives the opposite behavior of the weighing process S1c to the molding material Pe ... in the heating cylinder 2 is performed, so the molding material Pe ... Even in the case of molding a specific molding material Pe, which is easy to bite into the heating cylinder 2 and melts at a relatively low temperature, the problem that the screw 3 becomes idle in the measuring step S1c and measurement becomes impossible is solved. it can. In addition, when performing the lump process S10c, it is sufficient to rotate the screw 3 by a predetermined angle Rr in the opposite direction to the rotation direction during measurement between the injection process S3c and the measurement process S1c. It can be easily implemented by changing the software (control program) without accompanying a typical component. Therefore, the implementation can be facilitated and the cost can be reduced, and since there is no change such as addition of a fixing element, there is no possibility of adversely affecting the molding of other resin materials, and versatility and stability. Excellent (reliability). In particular, in the above embodiment, the measurement time Tmd from the start of measurement to the end of measurement in the measurement step S1c is monitored, and when the measurement time Tmd exceeds the set measurement abnormality determination time Tms, the subsequent molding to the injection process. If the splitting step S10c is performed between S3c and the measuring step S1c, it can be determined by the actual measuring time Tmd, so that even if the resin characteristic of the specific molding material Pe ... is unknown, it becomes impossible to measure. Can be reliably solved, and the effectiveness of the molding method according to the present invention can be enjoyed.

  On the other hand, FIG.7 and FIG.8 shows the shaping | molding method which concerns on the modified embodiment of this invention. In the molding method according to the modified embodiment, when molding with a specific molding material Pe ..., as shown in FIG. 7, the cooling time Tcd of the molded product after the injection step S3c is completed is monitored, and the continuous cooling time is monitored. When Tcd exceeds the set cooling limit determination time Tcs, the screw 3 is rotated in a direction opposite to the rotation direction during measurement by a predetermined angle Rr to form the molding material Pe in the heating cylinder 2. On the other hand, the lump process S10c which gives the opposite behavior of the weighing process is performed.

  FIG. 8 shows a simulation result with respect to a change in the measurement time with respect to the shot order using the cooling time Tcd of the molded product after the injection process as a parameter. In FIG. 8, C30 is when the cooling time Tcd is continuous for 30 [seconds], C60 is when the cooling time Tcd is continuous for 60 [seconds], C90 is when the cooling time Tcd is continuous for 90 [seconds], C120 Indicates a case where the cooling time Tcd continues for 120 seconds.

  When the continuous time of the cooling time Tcd becomes longer, the molding material Pe ... stays between the drop hole 13 and the screw flight 3f ... below the hopper 12, and the degree of progress of melting of the surface in that state increases. After that, even if the screw 3 is rotated, the possibility of idling increases. Therefore, the cooling limit determination time Tcs is set, and when the continuous cooling time Tcd exceeds the cooling limit determination time Tcs, the lump process S10c is performed. Thereby, the malfunction accompanying continuous cooling time Tcd becoming long can be avoided.

  For example, in the case of FIG. 8, if the cooling limit determination time Tcs is set to 60 [seconds], it becomes possible to avoid the inability to measure, so the cooling time Tcd between the weighing step S1c and the injection step S3c shown in FIG. For example, if it is 90 seconds, in this cooling time Tcd, after the injection step S3c is completed, after the elapse of 60 [seconds], the lump step S10c is performed. Therefore, when the cooling time Tcd is longer, the batching step S10c may be performed repeatedly every 60 [seconds]. In this case, the predetermined angle Rr to be used can be set in the range of 0.25 to 4 rotations (90 to 1440 [°]), preferably in the range of 0.25 to 2 rotations (90 to 720 [°]).

  Thus, if the cooling time Tcd of the molded product is monitored and the continuous cooling time Tcd exceeds the set cooling limit determination time Tcs, the lump step S10c is performed, so that the surface of the molding material Pe ... And the progress of sticking between the molding materials Pe ... can be stopped, so that even when the cooling time Tcd of the molded product becomes long, the problem that the measurement becomes impossible is surely eliminated, and the molding method according to the present invention You can enjoy the effectiveness.

  Moreover, FIG. 7 shows the case where return process S10cr for returning the screw 3 to the angle at the time of the start of the said chunk process S10c is performed after completion | finish of the chunk process S10c. That is, by the splitting step S10c, the screw 3 is rotated by a predetermined angle Rr in the opposite direction to the rotating direction at the time of weighing, so that the molding material Pe ... in the heating cylinder 2 is opposite to the weighing step S1c. Immediately after that, the return step S10cr is performed, and the screw 3 is rotated by the same angle Rr in the rotation direction at the time of measurement, thereby returning the screw 3 to the angle at the start of the bundling step S10c. It is what I did. Thereby, in particular, even when the cooling time Tcd becomes long and the number of times of the lump process S10c increases, the influence on the molten resin (measured value) after measurement that may be generated by the lump process S10c. Can be offset. In addition, when performing the lump process S10c and the return process S10cr, the position control which fixes the front-back direction position of the screw 3 is performed.

  As described above, the preferred embodiment and the modified embodiment have been described in detail. However, the present invention is not limited to such an embodiment, and the present invention is not limited to the detailed configuration, material, quantity, numerical value, method, and the like. Changes, additions and deletions can be made arbitrarily without departing from the scope.

  For example, according to the present invention, basically, when molding is performed with a specific molding material Pe ..., the screw 3 is placed between the injection step S3c and the metering step S1c in a direction opposite to the rotational direction during metering in a predetermined direction. Since it is an effective technique to perform the weighing step S1c, performing the lump step S10c that imparts the opposite behavior of the weighing step S1c to the molding material Pe ... in the heating cylinder 2 by rotating the angle Rr. If the resin characteristics and the like of the specific molding material Pe ... are clearly understood, a predetermined angle Rr may be set in advance, and the chunking step S10c may be performed for each shot from the beginning. In this case, the predetermined angle Rr to be used can be set in the range of 0.25 to 4 rotations (90 to 1440 [°]), preferably in the range of 0.25 to 2 rotations (90 to 720 [°]).

  Moreover, each exemplary embodiment can be used in combination. Therefore, for example, the measurement time Tmd from the start of measurement to the end of measurement in the measurement step S1c is monitored, and when the measurement time Tmd exceeds the set measurement abnormality determination time Tms, the separation is performed between the injection step S3c and the measurement step S1c. When performing the lump process S10c, from the start of molding until the measurement abnormality determination time Tms is exceeded, an initial lump process is performed in which the screw 3 is rotated in the opposite direction by the set basic angle Rro (for example, 180 [°]), When the measurement abnormality determination time Tms is exceeded, the lump process S10c in which the screw 3 is rotated in the opposite direction by a larger predetermined angle Rr (for example, 360 [°]) may be performed. In this way, if the initial bundling process in which the screw 3 is rotated in the opposite direction by the set initial setting angle (basic angle) Rro from the start of molding until the measurement abnormality determination time Tms is exceeded, a specific molding is performed. When the material Pe ... is used and there is a high possibility that measurement will not be possible, the initial lump process is performed from the beginning, so the sticking between the molding materials Pe ... is reduced and more accurate and stable measurement is possible. It can be carried out. Furthermore, the returning step S11c can also be used in combination with the lump step S10c (S10ce) in the other embodiments.

  On the other hand, the PCTA resin material is exemplified as the specific molding material Pe ..., but a PCTG resin material (manufactured by Eastman Chemical Co.) or a polylactic acid resin material which is a similar resin material, that is, a temperature of 100 [° C.] or less. It may be a resin material having a resin property of starting melting. If these specific molding materials Pe ... are used, these specific molding materials Pe ... having specific resin characteristics are suitable from the viewpoint of eliminating the problem of being unable to measure, and reliable and stable measurement. Further, molding can be performed. Of course, the use of a specific resin material Pe ... other than these examples is not excluded. In addition, the condition for determining that the measurement abnormality determination time Tms has been exceeded is a case where the condition is that the set number of determinations is continuously exceeded by 2, but the number of determinations may be set to 3 or more. The case of 1 is not excluded. Furthermore, the case where the measurement time Tmd is taken in and abnormality is determined based on the measurement abnormality determination time Tms is exemplified. However, instead of the measurement time, the measurement position or the set position is not reached even after a certain time has passed. You may judge.

  The molding method according to the present invention can be used for various types of injection molding machines having a measuring step of plasticizing and weighing a molding material made of resin pellets supplied into a heating cylinder by rotating a screw.

  M: injection molding machine, 2: heating cylinder, 3: screw, 4: mold, S1c: metering process, S3c: injection process, S10c (S10ce): lump process, S11c: return process, Pe ...: specific molding Material, Tmd: Measurement time, Tms: Measurement abnormality determination time, Tcd: Cooling time, Tcs: Cooling limit determination time

Claims (12)

  Injection molding comprising a measuring step for plasticizing and weighing a molding material made of resin pellets supplied into a heating cylinder by rotating a screw, and an injection step for injecting and filling the mold with the molten resin in the heating cylinder plasticized and measured In the molding method of the machine, when molding with a specific molding material, the screw is moved by a predetermined angle in the opposite direction to the rotation direction during metering from the end of the injection process to the start of the metering process. A molding method for an injection molding machine, characterized by performing a lump process for imparting a behavior opposite to that of the metering process to the molding material in the heating cylinder by rotating.   2. The specific molding material includes at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [° C.] or less. Injection molding machine molding method.   The injection molding machine molding method according to claim 1 or 2, wherein the predetermined angle is selected from 0.25 to 4 rotations.   Injection molding comprising a measuring step for plasticizing and weighing a molding material made of resin pellets supplied into a heating cylinder by rotating a screw, and an injection step for injecting and filling the mold with the molten resin in the heating cylinder plasticized and measured In the molding method of the machine, when molding with a specific molding material, the measurement time from the start of measurement to the end of measurement in the measurement process is monitored, and if the measurement time exceeds the set measurement abnormality determination time, Between the injection process and the metering process, the screw is rotated by a predetermined angle in the opposite direction to the rotating direction during metering, so that the opposite behavior of the metering process with respect to the molding material in the heating cylinder. A molding method for an injection molding machine, characterized by performing a lump process for imparting the above.   5. The specific molding material includes at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [deg.] C. or less. Injection molding machine molding method.   A basic angle is set in advance with respect to the predetermined angle, and when the measurement time exceeds the measurement abnormality determination time, the bundling process is performed only for the basic angle, and then the measurement time is 6. The molding method for an injection molding machine according to claim 4 or 5, wherein if the measurement abnormality determination time is exceeded, the bundling step is performed at a predetermined angle that is sequentially increased from the basic angle every time the measurement abnormality determination time is exceeded.   7. The molding method for an injection molding machine according to claim 6, wherein a limit angle is set in advance with respect to the predetermined angle, and an abnormal process is performed when the predetermined angle exceeds the limit angle.   The molding method for an injection molding machine according to any one of claims 4 to 7, wherein the condition for determining that the measurement abnormality determination time has been exceeded is that it has been continuously exceeded by a set number of determinations. .   The time between the injection process and the weighing process includes from the end of the injection process to the start of the measurement process, or from the end of the measurement process to the start of the injection process. A molding method for an injection molding machine according to claim 1.   Injection molding comprising a measuring step for plasticizing and weighing a molding material made of resin pellets supplied into a heating cylinder by rotating a screw, and an injection step for injecting and filling the mold with the molten resin in the heating cylinder plasticized and measured In the molding method of the machine, when performing molding with a specific molding material, monitoring the cooling time of the molded product after the injection process is completed, and when the cooling limit judgment time set continuous continuous cooling time exceeds, Performing a lump process that imparts the opposite behavior of the weighing process to the molding material in the heating cylinder by rotating the screw by a predetermined angle in the opposite direction to the rotating direction during weighing. A molding method for an injection molding machine.   11. The specific molding material includes at least a PCTA resin material, a PCTG resin material, or a polylactic acid resin material having a resin property of starting melting at a temperature of 100 [° C.] or less. Injection molding machine molding method.   12. The molding method for an injection molding machine according to claim 10 or 11, wherein a return step for returning the screw to the angle at the start of the split step is performed after the end of the split step.