JP6523129B2 - Injection molding machine - Google Patents

Description

  The present invention relates to an injection molding machine.

  In the injection molding machine described in Patent Document 1, a molding material (for example, a resin) heated in a cylinder is injected and filled in a mold to mold a molded article. The injection molding machine lowers the set temperature of the cylinder from the high temperature injection temperature to the standard molding temperature when the molding cycle is stopped. The injection molding machine performs intermittent purge to prevent resin burn until the set temperature of the cylinder falls to the standard molding temperature. The injection molding machine stops the purge while the set temperature of the cylinder is kept constant at the standard molding temperature. At the restart of the molding cycle, the injection molding machine raises the set temperature of the cylinder from the standard molding temperature to the high temperature injection temperature. At this time, the injection molding machine carries out intermittent purge.

Unexamined-Japanese-Patent No. 2010-99995

  In the past, the purge operation was performed when the temperature of the cylinder was raised from the heat retention temperature to the molding temperature, but substitution of the molding material in the cylinder was not sufficient, and the quality of the molded article was low after restart of the molding operation. was there.

  This invention is made in view of the said subject, Comprising: It aims at provision of the injection molding machine which can improve the quality of a molded article.

According to one aspect of the present invention, in order to solve the above problems,
A cylinder for heating the molding material supplied to the inside;
A delivery member disposed inside the cylinder for delivering the molding material to the outside of the cylinder;
A controller for controlling the operation of the delivery member and the temperature of the cylinder;
The operation of the delivery member includes a molding operation for filling the molding material in a mold apparatus and for molding a molded article, and a purge operation for replacing the molding material in the cylinder.
The control device performs the purge operation for the temperature of the cylinder during a temperature holding time set in advance when raising the temperature of the cylinder from a temperature keeping temperature for keeping the cylinder warm to a molding temperature for performing the forming operation. An injection molding machine is provided, which holds the purge operation at a predetermined temperature below the molding temperature above the purge temperature at which the permission is to be permitted.

  According to one aspect of the present invention, an injection molding machine is provided that can improve the quality of molded articles.

It is a figure which shows the state at the time of completion | finish of type | mold opening of the injection molding machine by one Embodiment. It is a figure which shows the state at the time of mold clamping of the injection molding machine by one Embodiment. FIG. 5 is a diagram showing a temperature pattern for raising the temperature of a cylinder from a heat retention temperature to a molding temperature according to one embodiment.

  Hereinafter, although the form for carrying out the present invention is explained with reference to drawings, the same or corresponding numerals are attached about the same or corresponding composition in each drawing, and explanation is omitted.

  FIG. 1 is a view showing a state of completion of mold opening of the injection molding machine according to one embodiment. FIG. 2 is a view showing a mold clamping state of the injection molding machine according to one embodiment.

  The injection molding machine has a frame Fr, a clamping device 10, an injection device 40, and a control device 90, as shown in FIGS. 1 and 2, for example.

  First, the mold clamping device 10 will be described. In the description of the mold clamping device 10, the moving direction of the movable platen 13 at the mold closing time (right direction in FIGS. 1 and 2) is the front, and the moving direction of the movable platen 13 at the mold opening time (left in FIG. The direction is described as the rear.

  The mold clamping device 10 performs mold closing, mold clamping and mold opening of the mold apparatus 30. The clamping device 10 includes a stationary platen 12, a movable platen 13, a support platen 15, tie bars 16, a toggle mechanism 20, a clamping motor 21, and a motion conversion mechanism 25.

  The fixed platen 12 is fixed relative to the frame Fr. A fixed mold 32 is attached to the surface of the fixed platen 12 facing the movable platen 13.

  The movable platen 13 is movable along a guide (for example, a guide rail) 17 laid on the frame Fr, and is movable back and forth with respect to the fixed platen 12. A movable mold 33 is attached to the surface of the movable platen 13 facing the fixed platen 12.

  By moving the movable platen 13 back and forth with respect to the fixed platen 12, mold closing, mold clamping and mold opening are performed. The mold apparatus 30 is configured by the fixed mold 32 and the movable mold 33.

  The support platen 15 is connected to the fixed platen 12 at a distance, and is movably mounted on the frame Fr in the mold opening and closing direction. The support platen 15 may be movable along a guide laid on the frame Fr. The guide of the support platen 15 may be common to the guide 17 of the movable platen 13.

  In the present embodiment, the fixed platen 12 is fixed to the frame Fr and the support platen 15 is movable relative to the frame Fr in the mold opening and closing direction, but the support platen 15 is fixed to the frame Fr and fixed 12 may be movable in the mold opening and closing direction with respect to the frame Fr.

  The tie bar 16 couples the fixed platen 12 and the support platen 15 at an interval. A plurality of tie bars 16 may be used. Each tie bar 16 is parallel to the mold opening / closing direction and extends in response to the clamping force. A clamping force detector 18 is provided on the at least one tie bar 16. The clamping force detector 18 may be a strain gauge type, and detects the clamping force by detecting the strain of the tie bar 16.

  The clamping force detector 18 is not limited to the strain gauge type, and may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like, and the mounting position thereof is not limited to the tie bar 16.

  The toggle mechanism 20 is disposed between the movable platen 13 and the support platen 15. The toggle mechanism 20 includes a crosshead 20a, a plurality of links 20b and 20c, and the like. One link 20 b is swingably attached to the movable platen 13, and the other link 20 c is swingably attached to the support platen 15. These links 20b and 20c are flexibly connected by pins or the like. By advancing and retracting the cross head 20 a, the links 20 b and 20 c are bent and extended, and the movable platen 13 is advanced and retracted with respect to the support platen 15.

  The clamping motor 21 is attached to the support platen 15, and advances and retracts the movable platen 13 by advancing and retracting the crosshead 20a. A motion conversion mechanism 25 is provided between the mold clamping motor 21 and the crosshead 20a for converting the rotational movement of the mold clamping motor 21 into a linear motion and transmitting it to the crosshead 20a. The motion conversion mechanism 25 is configured by, for example, a ball screw mechanism. The position and speed of the cross head 20 a are detected by, for example, an encoder 21 a of the mold clamping motor 21.

  The operation of the mold clamping device 10 is controlled by the controller 90. The controller 90 controls a mold closing process, a mold clamping process, a mold opening process, and the like.

  In the mold closing process, the mold clamping motor 21 is driven to move the movable platen 13 forward to bring the movable mold 33 into contact with the fixed mold 32.

  In the mold clamping process, the mold clamping force is generated by further driving the mold clamping motor 21. During clamping, a cavity space 34 is formed between the movable mold 33 and the fixed mold 32, and the cavity space 34 is filled with a liquid molding material. The molding material in the cavity space 34 is solidified and becomes a molded article.

  In the mold opening process, the movable mold 33 is separated from the fixed mold 32 by driving the mold clamping motor 21 to retract the movable platen 13.

  In addition, although the mold clamping device 10 of this embodiment has the mold clamping motor 21 as a drive source, it may have a hydraulic cylinder instead of the mold clamping motor 21. The mold clamping device 10 may have a linear motor for mold opening and closing and an electromagnet for mold clamping.

  Next, the injection device 40 will be described. In the description of the injection device 40, unlike the description of the mold clamping device 10, the moving direction of the screw 43 at the time of filling (left direction in FIGS. 1 and 2) is the front, and the moving direction of the screw 43 at the time of metering (FIG. The right direction in FIG. 2 will be described as the rear.

  The injection device 40 is installed on a slide base Sb which can be advanced and retracted with respect to the frame Fr, and can be advanced and retracted with respect to the mold apparatus 30. The injection device 40 is touched to the mold device 30 as shown in FIG. 2 and the molding device 30 is filled with a molding material.

  The injection device 40 includes, for example, a cylinder 41, a screw 43, a metering motor 45, an injection motor 46, a pressure detector 47, and the like.

  The cylinder 41 heats the molding material supplied to the inside from the supply port 41a. The supply port 41 a is formed at the rear of the cylinder 41. The cylinder 41 has at its front end a nozzle 42 which is pressed against the mold assembly 30. The nozzle 42 is a part of the cylinder 41. A heating source 48 such as a heater is provided on the outer periphery of the cylinder 41.

  The cylinder 41 is divided into a plurality of zones in the axial direction of the cylinder 41 (left and right direction in FIGS. 1 and 2). A heating source 48 and a temperature detector 49 are provided in each zone. The controller 90 controls the heating source 48 so that the measured temperature of the temperature detector 49 becomes the set temperature for each zone.

  The screw 43 is rotatably and retractably disposed in the cylinder 41. The screw corresponds to the delivery member as claimed.

  The metering motor 45 feeds the molding material forward along the spiral groove of the screw 43 by rotating the screw 43. The molding material is gradually melted by the heat from the cylinder 41 while being sent forward. As liquid molding material is fed to the front of the screw 43 and accumulated at the front of the cylinder 41, the screw 43 is retracted.

  The injection motor 46 advances and retracts the screw 43. The injection motor 46 advances the screw 43 to inject the liquid molding material accumulated in front of the screw 43 from the cylinder 41 and fill the inside of the mold apparatus 30. Thereafter, the injection motor 46 pushes the screw 43 forward to apply pressure to the molding material in the mold apparatus 30. The shortage of molding material can be replenished. Between the injection motor 46 and the screw 43, a motion conversion mechanism that converts the rotational movement of the injection motor 46 into the linear motion of the screw 43 is provided.

  The pressure detector 47 is disposed, for example, between the injection motor 46 and the screw 43, and detects the pressure that the screw 43 receives from the molding material, the back pressure to the screw 43, and the like. The pressure that the screw 43 receives from the molding material corresponds to the pressure that acts on the molding material from the screw 43.

  The operation of the injection device 40 is controlled by the controller 90. The controller 90 controls the filling process, the pressure holding process, the measuring process, and the like.

  In the filling step, the injection motor 46 is driven to advance the screw 43 at a set speed, and the liquid molding material accumulated in front of the screw 43 is filled into the mold apparatus 30. The position and speed of the screw 43 are detected by, for example, the encoder 46 a of the injection motor 46. When the position of the screw 43 reaches a predetermined position, switching from the filling process to the pressure holding process (so-called V / P switching) is performed.

  In addition, after the position of the screw 43 reaches a predetermined position in the filling process, the screw 43 may be temporarily stopped at the predetermined position, and then the V / P switching may be performed. Just before the V / P switching, instead of stopping the screw 43, a slow advance or slow retreat of the screw 43 may be performed.

  In the pressure holding process, the injection motor 46 is driven to push the screw 43 forward with a set pressure, and pressure is applied to the molding material in the mold apparatus 30. The shortage of molding material can be replenished. The pressure of the molding material is detected by, for example, a pressure detector 47. In the pressure holding process, the molding material in the mold apparatus 30 is gradually cooled, and at the completion of the pressure holding process, the inlet of the cavity space 34 is blocked with the solidified molding material. This state is called a gate seal, and backflow of molding material from the cavity space 34 is prevented. After the pressure holding step, the cooling step is started. In the cooling step, solidification of the molding material in the cavity space 34 is performed. A metering step may be performed during the cooling step to shorten the molding cycle.

  In the metering process, the metering motor 45 is driven to rotate the screw 43 at a set rotational speed, and the molding material is fed forward along the spiral groove of the screw 43. Along with this, the molding material is gradually melted. As liquid molding material is fed to the front of the screw 43 and accumulated at the front of the cylinder 41, the screw 43 is retracted. The number of rotations of the screw 43 is detected by, for example, an encoder 45 a of the measuring motor 45.

  In the measurement process, the injection motor 46 may be driven to apply a set back pressure to the screw 43 in order to limit the rapid retraction of the screw 43. The back pressure on the screw 43 is detected by, for example, a pressure detector 47. When the screw 43 retracts to a predetermined position and a predetermined amount of molding material is accumulated in front of the screw 43, the measurement process is completed.

  The control device 90 includes a CPU (Central Processing Unit) 91 and a storage medium 92 such as a memory as shown in FIG. 1 and FIG. The control device 90 controls the mold clamping device 10, the injection device 40, and the like by causing the CPU 91 to execute the program stored in the storage medium 92.

  The controller 90 holds the temperature of the cylinder 41 at the molding temperature while performing the molding operation of filling the molding material into the mold apparatus 30 and molding the molded product. The molding temperature is a temperature at which a molding operation is performed. The molding temperature is appropriately set according to the size and shape of the molded product, the type of resin of the molding material, and the like, and is set for each zone.

  When stopping the molding operation, the controller 90 stops the molding operation, and then lowers the temperature of the cylinder 41 from the molding temperature to the heat retention temperature, and holds the temperature at the heat retention temperature. The incubation temperature may be the same temperature or different temperatures in multiple zones. The timing to start lowering the temperature of the cylinder 41 from the molding temperature may be different at the same time in a plurality of zones. Further, the timing at which the temperature of the cylinder 41 reaches the heat retention temperature may be simultaneous or different in a plurality of zones.

  The heat retention temperature is a temperature at which the cylinder 41 is kept warm. The heat retention temperature is appropriately set according to the type of resin of the molding material, the heat retention time (time for keeping the temperature of the cylinder 41 at the heat retention temperature), and the like so as to suppress the thermal deterioration of the molding material remaining in the cylinder 41. Ru. While the temperature of the cylinder 41 is maintained at the heat retention temperature, the operation of the screw 43 (a purge operation described later besides the forming operation) is not performed.

  When restarting the molding operation, the control device 90 raises the temperature of the cylinder 41 from the heat retention temperature to the molding temperature and holds the temperature at the molding temperature prior to the restart of the molding operation. The forming temperature is set for each zone as described above. The timing to start raising the temperature of the cylinder 41 from the heat retention temperature may be different at the same time in a plurality of zones. Further, the timing at which the temperature of the cylinder 41 reaches the molding temperature may be simultaneous or different in a plurality of zones. After the temperature of the cylinder 41 reaches the molding temperature in all zones, the molding operation is performed.

  The controller 90 monitors whether the temperature of the cylinder 41 is equal to or higher than the purge temperature when raising the temperature of the cylinder 41 from the heat retention temperature to the molding temperature. The purge temperature may be the same temperature or different temperatures in multiple zones. The timing at which the temperature of the cylinder 41 reaches the purge temperature may be different or simultaneous in a plurality of zones.

  The purge temperature is a temperature at which permission of a purge operation described later starts when the temperature of the cylinder 41 is raised from the heat retention temperature to the molding temperature. The purge temperature is appropriately set according to the type of resin of the molding material and the like so that the viscosity of the molding material is lowered to such an extent that the purge operation can be performed.

  The purge operation is an operation of replacing the molding material in the cylinder 41 from the old one to the new one. The purge operation is performed in a state where the injection device 40 is retracted from the mold device 30 as shown in FIG. In the purge operation, no molded article is formed.

  The purge operation may include the rotation of the screw 43 and the advancing and retracting of the screw 43. As the controller 90 rotates the screw 43, the molding material is sent forward along the spiral groove of the screw 43. As the molding material accumulates in the front of the cylinder 41, the screw 43 is retracted. Thereafter, as the control device 90 advances the screw 43, the molding material accumulated in front of the screw 43 is ejected from the nozzle 42.

  During the purge operation, the controller 90 may rotate the screw 43 at the retracted limit position without advancing the screw 43 after the screw 43 retracts. In addition, during the purge operation, the control device 90 may rotate the screw 43 while restricting the advancing and retracting of the screw 43 in front of the retracted limit position of the screw 43. In any case, replacement of the molding material in the cylinder 41 is possible.

  The controller 90 performs the purge operation at a predetermined timing. For example, after permitting the purge operation, the control device 90 starts the purge operation according to a predetermined command (for example, a predetermined input operation by the operator of the injection molding machine). In addition, the control device 90 may automatically start the purge operation when the purge operation is permitted.

  The controller 90 performs the purge operation intermittently or continuously. When the purge operation is performed intermittently, the control device 90 may perform the purge operation every predetermined time, or may perform the purge operation every predetermined temperature.

  The controller 90 ends the purge operation before resuming the molding operation. The controller 90 may perform the purge operation while maintaining the temperature of the cylinder 41 at the molding temperature, before the restart of the molding operation.

  The control device 90 may perform the purge operation until the temperature of the cylinder 41 reaches the purge temperature when lowering the temperature of the cylinder 41 from the molding temperature to the heat retention temperature.

  FIG. 3 is a diagram showing a temperature pattern for raising the temperature of the cylinder from the heat retention temperature to the molding temperature according to one embodiment. The temperature pattern shown in FIG. 3 is the temperature pattern of one zone, but the temperature patterns of the other zones may be similar to the temperature pattern shown in FIG. The temperature pattern of each zone is stored in the storage medium 92 of the controller 90 and read out and used. In FIG. 3, the heat retention temperature T1 is set to a temperature lower than the purge temperature T2.

  The controller 90 raises the temperature of the cylinder 41 from the heat retention temperature T1 to the purge temperature T2. Since the viscosity of the molding material inside the cylinder 41 is too high while the temperature of the cylinder 41 is less than the purge temperature T2, the controller 90 prohibits the purge operation.

  Subsequently, the control device 90 holds the temperature of the cylinder 41 at the purge temperature T2 in a state where the purge operation is prohibited, for the cold start prevention time D1 set in advance. The cold start prevention time D1 is a waiting time until the temperature of the molding material in the cylinder 41 becomes approximately the same as the temperature of the cylinder 41. The cold start prevention time D1 is appropriately set according to the heat transfer characteristic from the cylinder 41 to the molding material. The cold start prevention time D1 may not be provided.

  When the timing for causing the temperature of the cylinder 41 to reach the purge temperature T2 is simultaneous in a plurality of zones, the cold start prevention time D1 may be the same time in a plurality of zones. The end timing of the cold start prevention time D1 becomes simultaneous in a plurality of zones.

  On the other hand, when the timing at which the temperature of the cylinder 41 is caused to reach the purge temperature T2 is different in a plurality of zones, different colds in a plurality of zones are cold so that the end timing of the cold start prevention time D1 becomes simultaneous in a plurality of zones. The inter-start prevention time D1 may be set.

  Subsequently, the controller 90 raises the temperature of the cylinder 41 from the purge temperature T2 to the molding temperature T3. At this time, the control device 90 holds the temperature of the cylinder 41 at a predetermined temperature between the purge temperature T2 and the molding temperature T3 while permitting the purge operation for a preset temperature holding time D2. For example, after the elapse of the cold start prevention time D1, the control device 90 holds the temperature of the cylinder 41 at the purge temperature T2 while permitting the purge operation for the temperature holding time D2. The temperature holding time D2 is set according to the heat retention temperature T1, the heat retention time, and the like. During the temperature holding time D2, execution of a purge operation by the controller 90 is possible.

  As described above, according to the present embodiment, when raising the temperature of the cylinder 41 from the heat retention temperature T1 to the molding temperature T3, a state in which the purge operation is permitted at a predetermined temperature between the purge temperature T2 and the molding temperature T3. Temperature holding time D2 is added. Therefore, as compared with the conventional case where the temperature of the cylinder 41 is continuously raised from the purge temperature T2 to the molding temperature T3 immediately after permitting the purge operation, the time for which the purge operation is possible is longer, and the cylinder is started before the molding operation starts. The substitution of the molding material in 41 is sufficiently made. The old one having a long residence time in the cylinder 41 can be sufficiently discharged, and the quality of the molded product can be improved.

  This effect is obtained if the temperature holding time D2 is added to the temperature pattern of at least one zone. The temperature holding time D2 may not be added to the temperature patterns of all the zones. It may be selectable whether the temperature holding time D2 is added to the temperature pattern of any of a plurality of zones. For example, the control device 90 selects which zone temperature pattern to add the temperature holding time D2 in accordance with the user's input operation on the input device such as a touch panel. Further, the control device 90 may select which zone temperature pattern to add the temperature holding time D2 based on the quality of the molded product and the like.

  When the temperature holding time D2 is added to the temperature patterns of the plurality of zones, the start timing, the end timing, and the length of the temperature holding time D2 may be the same or different in the plurality of zones. Preferably, there is a timing at which the temperature holding time D2 of the temperature pattern of one zone and the temperature holding time D2 of the temperature pattern of the other zone overlap.

  By the way, as the viscosity of the molding material in the cylinder 41 is lower, new and old ones are less likely to be mixed, and old ones are more likely to be discharged to the outside of the cylinder 41 before new ones. Therefore, it is preferable to maintain the temperature of the cylinder 41 at a purge temperature T2 at which permission of the purge operation is started.

  In the present embodiment, the temperature of the cylinder 41 held while permitting the purge operation is the purge temperature, but it may be a predetermined temperature which is higher than the purge temperature T2 and lower than the molding temperature T3. Further, the number of temperatures of the cylinder 41 held in a state where the purge operation is permitted may not be one, but may be plural. In the latter case, the plurality of temperature holding times D2 may be the same time or different times.

  In FIG. 3, since the heat retention time is long, the heat retention temperature T1 is set to a temperature lower than the purge temperature T2, but if the heat retention time is short, the heat retention temperature T1 may be a temperature high enough to enable the purge operation. In this case, the purge operation can be performed with the temperature of the cylinder 41 remaining at the heat retention temperature T1, so the purge temperature T2 may be the same temperature as the heat retention temperature T1.

  Although the embodiment and the like of the injection molding machine have been described above, the present invention is not limited to the above embodiment and the like, and various modifications may be made within the scope of the subject matter of the present invention described in the claims. An improvement is possible.

  Although the injection device 40 of the said embodiment is an in-line screw system, it may be a pre plastic system. The pre-plasticizer type injection apparatus supplies the molding material melted in the plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into the mold apparatus. A screw is rotatably or rotatably and retractably disposed in the plasticizing cylinder, and a plunger is movably disposed in the injection cylinder. In the case of the pre-plastic system, at least one of the screw and the plunger corresponds to the delivery member recited in the claims, and at least one of the plasticizing cylinder and the injection cylinder corresponds to the cylinder recited in the claims.

Reference Signs List 30 mold apparatus 32 fixed mold 33 movable mold 34 cavity space 40 injection apparatus 41 cylinder 43 screw 48 heating source 49 temperature detector 90 control device

Claims (4)

A cylinder for heating the molding material supplied to the inside;
A delivery member disposed inside the cylinder for delivering the molding material to the outside of the cylinder;
A controller for controlling the operation of the delivery member and the temperature of the cylinder;
The operation of the delivery member includes a molding operation for filling the molding material in a mold apparatus and for molding a molded article, and a purge operation for replacing the molding material in the cylinder.
The control device performs the purge operation for the temperature of the cylinder during a temperature holding time set in advance when raising the temperature of the cylinder from a temperature keeping temperature for keeping the cylinder warm to a molding temperature for performing the forming operation. An injection molding machine that holds the purge operation at a predetermined temperature below the molding temperature above the purge temperature to start permitting the purge operation.   The control device holds the temperature of the cylinder at the purge temperature while permitting the purge operation during the temperature holding time when raising the temperature of the cylinder from the heat retention temperature to the molding temperature. The injection molding machine according to claim 1.   When the temperature of the cylinder is raised from the heat retention temperature to the purge temperature, the control device prohibits the purge operation at the temperature of the cylinder at the purge temperature during a cold start prevention time set in advance. The temperature of the cylinder is held at the purge temperature while the purge operation is permitted during the temperature holding time after the cold start prevention time has elapsed. Injection molding machine as described.   The injection molding machine according to any one of claims 1 to 3, wherein the control device performs the purge operation at a predetermined timing during the temperature holding time.

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