TWI623408B - Injection molding machine, setting device for injection molding machine, and setting method of injection molding machine - Google Patents

Abstract

The present invention provides an injection molding machine, a setting device for the injection molding machine, and a method for setting the injection molding machine. The injection molding machine can improve the stability of the quality of the molded product. The injection molding machine of the present invention includes a heating cylinder having a supply port at the rear; a material supply device that supplies the molding material to the supply port; a screw that rotates the heating cylinder to feed the molding material forward; A setting device sets a molding condition, and the setting device sets a relationship between a rotation speed of the screw and a supply speed of the material supply device according to a deviation of a mold internal pressure.

Description

Injection molding machine, setting device for injection molding machine, and setting method of injection molding machine

The present invention relates to an injection molding machine, a setting device for the injection molding machine, and a method for setting the injection molding machine.

The injection molding machine includes a heating cylinder, a material supply device that supplies the molding material into the heating cylinder, and a screw that is rotatably and advancing in and out of the heating cylinder (see, for example, Patent Document 1). When the screw is rotated, the molding material is sent forward along the spiral groove of the screw. The molding material is gradually melted while moving forward. As the liquid forming material accumulates in front of the screw, the screw is forced to retreat. Thereafter, if the screw is advanced, the molding material in front of the screw is filled into the mold device from the heating cylinder. The molding material in the mold device is cooled and solidified to obtain a molded product.

(Prior technical literature) (Patent Literature)

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-351661

In the metering process, the molding material is sent forward as the screw rotates. The filling state of the molding material in the groove of the screw is determined by the rotation speed of the screw and the supply speed of the material supply device. When the rotation speed of the screw is constant, as the supply speed of the material supply device becomes larger, the above-mentioned filling state becomes more dense. The above-mentioned filling state affects the stability of the quality of the molded product.

This invention was made in view of the said subject, and an object of this invention is to provide the injection molding machine which can improve the stability of the quality of a molded article.

In order to solve the above-mentioned problems, an injection molding machine according to the present invention is provided. The injection molding machine includes: a heating cylinder having a supply port at the rear; a material supply device for supplying a molding material to the supply port; Internal rotation to send the forming material to the front; and a setting device for setting the forming conditions, the setting device setting the relationship between the rotation speed of the screw and the supply speed of the material supply device according to the deviation of the internal pressure of the mold.

According to the aspect of the present invention, an injection molding machine capable of improving the stability of the quality of a molded product can be obtained.

10‧‧‧ heating cylinder

20‧‧‧Screw

21‧‧‧Screw body

22‧‧‧ Injection Department

23‧‧‧spiral fin section

24‧‧‧Pressure

26‧‧‧slot

52‧‧‧Measuring motor

54‧‧‧ Injection motor

56‧‧‧Pressure detector

60‧‧‧Material supply device

63‧‧‧Feeding cylinder

67‧‧‧Feed screw

69‧‧‧Feed motor

70‧‧‧controller

80‧‧‧ display device

Fig. 1 is a view showing an injection molding machine according to an embodiment of the present invention.

Hereinafter, the embodiments for implementing the present invention will be described with reference to the drawings. However, in each drawing, the same or corresponding components are denoted by the same or corresponding component symbols, and the description is omitted. The description will be made assuming that the moving direction of the screw 20 during filling (left direction in the first figure) is forward, and the moving direction of the screw 20 during measurement (right direction in first figure) is backward.

Fig. 1 is a view showing an injection molding machine according to an embodiment of the present invention. The injection molding machine includes a heating cylinder 10, a screw 20, a metering motor 52, an injection motor 54, a pressure detector 56, a material supply device 60, a controller 70, and a display device 80.

The heating cylinder 10 heats the molding material supplied from the supply port 12. The supply port 12 is formed at the rear of the heating cylinder 10. A heating source such as a heater is provided on the outer periphery of the heating cylinder 10. A nozzle 14 is provided at the front end of the heating cylinder 10.

The screw 20 is disposed in the heating cylinder 10 so as to rotate freely and move forward and backward. The screw 20 is mainly composed of a screw main body 21 and an ejection portion 22 which is arranged further forward than the screw main body 21. The screw main body 21 includes a helical fin portion 23 and a pressure portion 24 arranged at a front end of the helical fin portion 23.

The helical fin portion 23 includes a rod-shaped main body portion 23a and a spiral helical fin 23b protrudingly formed on the outer peripheral surface of the main body portion 23a. A spiral groove 26 is formed around the spiral fin 23b. The depth of the groove 26 may be constant from the rear end to the front end of the spiral fin portion 23, and the screw compression ratio may also be constant.

The pressure portion 24 may be a cylindrical portion having an outer diameter larger than the rod-shaped body portion 23a. Between the main body portion 23a and the cylindrical portion, a conical frustum-shaped inclined portion (not shown) may be provided, and the outer diameter of the inclined portion gradually increases from the main body portion 23a to the cylindrical portion. The inclined portion and the cylindrical portion may also form a pressure部 24。 24.

In addition, a spiral fin portion may be formed throughout the entire screw body 21 without providing the pressure portion 24. The screw body 21 can be divided into a supply section, a compression section, and a metering section from the rear end to the front end. At this time, the depth of the spiral groove is deeper in the supply section, shallower in the metering section, and shallower toward the front in the compression section.

The injection portion 22 includes a head portion 31 having a conical portion at the front end, a rod portion 32 formed adjacent to the rear of the head portion 31, a backflow prevention ring 33 disposed around the rod portion 32, and a seal ring. (Lock ring) 34 is attached to the front end of the pressure portion 24.

The metering motor 52 rotates the screw 20. The metering motor 52 may have an encoder 52a. The encoder 52a detects the rotation speed of the screw 20 by detecting the rotation speed of the output shaft of the metering motor 52, and outputs a signal indicating the rotation speed to the controller 70. The controller 70 feedback-controls the metering motor 52 during the metering process so that the rotation speed of the screw 20 becomes a set value.

The injection motor 54 advances and retracts the screw 20. Between the screw 20 and the injection motor 54, a motion conversion unit that converts a rotational motion of the injection motor 54 into a linear motion of the screw 20 is provided. The injection motor 54 may have an encoder 54a. The encoder 54 a detects the forward speed of the screw 20 by detecting the rotation speed of the output shaft of the injection motor 54, and outputs a signal indicating the forward speed of the screw 20 to the controller 70. The controller 70 feedback-controls the injection motor 54 during the filling process so that the forward speed of the screw 20 becomes a set value.

The pressure detector 56 is disposed between the injection motor 54 and the screw 20, for example, and detects the pressure acting on the pressure detector 56. This pressure indicates the back pressure of the screw 20 and the pressure of the molding material pushed by the screw 20. The pressure detector 56 outputs a signal indicating the pressure acting on the pressure detector 56 to the controller 70. The controller 70 feedback-controls the injection motor 54 during the holding process so that the pressure of the molding material pushed by the screw 20 becomes a set value. The controller 70 feedback-controls the injection motor 54 during the measurement process so that the back pressure of the screw 20 becomes a set value.

In the filling process, the injection motor 54 is driven to advance the screw 20 and the liquid molding material accumulated in front of the screw 20 is filled in the mold device. The setting value of the forward speed of the screw 20 may be constant or may be changed according to the screw position or the elapsed time. When the screw 20 advances to a predetermined position (so-called V / P switching position), the holding process is started. In addition, if the elapsed time after starting the filling process reaches a predetermined time, the holding process may also be started.

During the holding process, the injection motor 54 is driven to push the screw 20 forward and apply pressure to the molding material in the mold device. Can replenish inadequate molding materials. The setting value of the pressure of the molding material may be constant, or may be gradually changed according to elapsed time or the like. After the holding process, the cooling process is started. In the cooling process, a metering process can be performed.

During the measurement process, the measurement motor 52 is driven to rotate the screw 20 and feed the molding material forward along the spiral groove 26 of the screw 20. The forming material is gradually melted. As the liquid forming material is sent to the front of the screw 20 and accumulated in the front of the heating cylinder 10, the screw 20 is forced to retreat. The setting value of the rotation speed of the screw 20 may be constant, or may be changed according to the screw position or the elapsed time.

In the measurement process, in order to limit the rapid retreat of the screw 20, the injection motor 54 may be driven to apply back pressure to the screw 20. The injection motor 54 is driven so that the back pressure becomes a set value. When the screw 20 is retracted to a predetermined position, and a predetermined amount of molding material is accumulated in front of the screw 20, the measurement process is ended.

In addition, although the injection device of this embodiment is a coaxial screw type, it may be a screw pre-molding type. In the screw pre-molding injection device, the molding material melted in the plasticizing cylinder is supplied to the injection cylinder, and the molding material is injected from the injection cylinder into the mold device. A screw is rotatably arranged in the plasticizing cylinder or freely advancing and retracting, and a plunger is disposed in the injection cylinder.

The material supply device 60 supplies the molding material to the supply port 12 of the heating cylinder 10 at a set supply speed. The material supply device 60 includes a hopper 61, a feed cylinder 63, a cylindrical guide 65, a feed screw 67, a feed motor 69, and the like.

The feed cylinder 63 extends horizontally from the lower end of the hopper 61 and houses the molding material supplied from the inside of the hopper 61. In addition, the feed cylinder 63 does not have to extend in the horizontal direction, for example, it may extend obliquely with respect to the horizontal direction, and the exit side may be higher than the entrance side.

The feed screw 67 is rotatably disposed in the feed cylinder 63.

The feed motor 69 rotates the feed screw 67. The feed motor 69 may have an encoder 69a. The encoder 69a detects the rotation speed of the feed screw 67 by detecting the rotation speed of the output shaft of the feed motor 69, and outputs a signal indicating the rotation speed to the controller 70. The controller 70 feedback-controls the feed motor 69 during the weighing process so that the rotation speed of the feed screw 67 becomes a set value.

The feed motor 69 rotates the feed screw 67 to feed the molding material forward along the spiral groove of the feed screw 67. The molding material is sent from the front end of the feed cylinder 63 to the guide 65, falls into the guide 65, and is supplied to the supply port 12 of the heating cylinder 10.

In the weighing process, the feed motor 69 is driven to rotate the feed screw 67, and the molding material is supplied to the supply port 12 of the heating cylinder 10. Its supply speed is proportional to the rotation speed of the feed screw 67. The setting value of the rotation speed of the feed screw 67 is the same as the setting value of the rotation speed of the screw 20, and may be constant or may be changed depending on the screw position or elapsed time.

The feed screw 67 and the screw 20 can rotate synchronously, and can also start rotating at the same time and end the rotation at the same time. The molding material does not stay at the supply port 12 but is sent forward by the rotation of the screw 20. The filling state of the molding material in the groove 26 of the screw 20 is not a dense state but a loose state (starved state).

In addition, the feed screw 67 may start the rotation earlier than the screw 20 and end the rotation earlier. The time difference may be, for example, the falling time of the molding material in the guide 65.

The controller 70 includes a storage unit 72 such as a memory and a CPU (Central Processing Unit 74 controls various operations of the injection molding machine by executing a control program stored in the storage unit 72 in the CPU 74. The controller 70 can function as a setting device for setting the molding conditions.

In the present embodiment, the controller 70 can function as a setting device, but the setting device may be provided separately from the controller 70.

However, in the measurement process, the molding material is sent forward as the screw 20 rotates. The filling state of the molding material in the groove 26 of the screw 20 (hereinafter also simply referred to as “filling state”) is determined by the rotation speed of the screw 20 and the supply speed of the material supply device 60. When the rotation speed of the screw 20 is constant, as the supply speed of the material supply device 60 becomes larger, the filling state becomes denser. The filling state affects the stability of the quality of the molded product.

Therefore, the controller 70 sets the relationship between the rotation speed of the screw 20 and the supply speed of the material supply device 60. The rotation speed of the feed screw 67 can be used as the supply speed of the material supply device 60, and the ratio of the rotation speed of the screw 20 to the rotation speed of the feed screw 67 can be used as the above relationship. This ratio can be expressed as a percentage of the rotation speed of the feed screw 67 to the rotation speed of the screw 20 (hereinafter also referred to as "synchronization rate").

Since the controller 70 sets the synchronization rate, it is possible to measure deviations in the mold internal pressure (hereinafter also referred to as “mold internal pressure deviations”) for each synchronization rate. The internal pressure of the mold is the pressure of the molding material in the mold device, and can be detected by a pressure detector provided in the mold device. When the internal pressure of the mold is stable, the density of the molded product and the weight of the molded product are stable.

The deviation of the internal pressure of the mold is the deviation of the measured value when the internal pressure of the mold is measured for each injection, and it is the difference caused by the injection. Its measured value can be peak, Any of a value at the time of V / P switching, a time integration value, and the like. As the deviation, a difference between a maximum value and a minimum value, a standard deviation, a coefficient of variation, and the like are used.

The controller 70 measures the deviation of the internal pressure of the mold for each synchronization rate, thereby obtaining the relationship between the synchronization rate and the deviation of the internal pressure of the mold. In this way, the controller 70 sets the synchronization rate according to the deviation of the internal pressure of the mold. The internal pressure of the mold is stable, and the density of the molded product and the weight of the molded product are stable.

The smaller the synchronization rate, the smaller the deviation in the internal pressure of the mold. It is inferred that the smaller the synchronization rate, the more the filled state becomes a loose state, and the formed material can be uniformly heated. In addition, it is considered that the frictional resistance when the screw 20 advances and retreats is reduced because the filling state becomes a loose state, and the screw 20 advances and retracts smoothly.

The controller 70 can set the synchronization rate according to the deviation of the internal pressure of the mold and other parameters. For example, the controller 70 may set the synchronization rate so that the measurement time does not exceed the cooling time (so that the measurement process ends in the cooling process). When the rotation speed of the screw 20 is constant, the smaller the synchronization rate, the smaller the supply speed of the material supply device 60, and the longer the measurement time.

However, in the measurement process, the molding material is compressed by a back pressure of the screw 20 and a shear stress caused by the rotation of the screw 20. After the rotation of the screw 20 is stopped, since the compressed molding material is expanded, pressure is applied to the screw 20 in a stopped state. This pressure is called a residual pressure.

The residual pressure acting on the screw 20 after the measurement process corresponds to the density of the molding material in front of the screw 20. Since the molding material in front of the screw 20 is filled in the mold device in a filling process or the like, the internal pressure of the mold and the residual pressure are related to each other.

Therefore, the controller 70 may use a residual pressure deviation (hereinafter also referred to as a “residual pressure deviation”) as a deviation of the internal pressure of the mold for setting the synchronization rate. When the residual pressure is stable, the density of the molded product and the weight of the molded product are stable.

The residual pressure can be detected by the pressure detector 56. The pressure detector 56 is used for the controller of the metering process and the holding process, rather than a dedicated product. Therefore, it is excellent in usability, cost, and the like.

The residual pressure deviation is a deviation of a measured value at the time of measuring the residual pressure for each injection, and is a difference caused by the injection. The measurement value may be any of a time integral value (for example, a time integral value from the end of the measurement process to a predetermined time), a value for a predetermined time (for example, when a predetermined time has elapsed from the end of the measurement process), and a peak value. As the deviation, a difference between a maximum value and a minimum value, a standard deviation, a coefficient of variation, and the like can be used. In addition, the residual pressure can be measured while the position of the screw 20 is maintained at the rotation stop position.

The controller 70 may set the synchronization rate according to the deviation of the internal pressure of the mold (including the residual pressure deviation) and the deviation of the measurement time. If the measurement time is stable, the heating time of the molding material is stable, and thermal degradation of the molding material can be suppressed, so the material of the molded product is stable.

The measurement time can be measured by a timer 76 or the like provided in the controller 70. The measurement time deviation is the deviation of the measured value when measuring the measurement time of each shot, and is the difference caused by the shot. As the deviation, a difference between a maximum value and a minimum value, a standard deviation, a coefficient of variation, and the like can be used. Since the measurement time is different from the internal pressure of the mold (including the residual pressure as the internal pressure of the mold) and changes according to the synchronization rate, a variation coefficient capable of reducing the influence of the change is particularly preferable. The coefficient of variation is the standard deviation divided by the average.

The smaller the synchronization rate, the larger the measurement time deviation tends to be. It is inferred that the smaller the synchronization rate is, the more the filling state of the molding material in the groove 26 of the screw 20 becomes a loose state, a gap is formed between the molding materials, and the transportation of the molding material becomes unstable.

The smaller the synchronization rate, the smaller the deviation of the internal pressure of the mold, and the larger the deviation of the measurement time. The deviation of the internal pressure of the mold and the deviation of the measurement time indicate different trends.

When the controller 70 sets the synchronization rate according to the mold internal pressure deviation (including residual pressure deviation) and the measurement time deviation, the controller 70 can set the synchronization rate according to the product of the mold internal pressure deviation and the measurement time deviation, and can set the synchronization rate such that the above The product becomes the minimum. The stability of the density of the molded product and the weight of the molded product and the stability of the material of the molded product can be taken into consideration. In addition, the controller may set the synchronization rate according to the above product and other parameters. At this time, the above product may not become the minimum value.

When the controller 70 sets the synchronization rate according to the deviation of the internal pressure of the mold (including the residual pressure deviation), it can use the measurement time deviation to correct the synchronization rate.

Since the controller 70 sets the synchronization rate, the measurement time deviation of each synchronization rate can be measured. If the measurement time is stable, the heating time of the molding material is stable and the thermal degradation of the molding material can be controlled, so the material of the molded product is stable.

The measurement time can be measured by a timer 76 or the like provided in the controller 70. As the deviation of the measurement time, a difference between a maximum value and a minimum value, a standard deviation, a coefficient of variation, and the like can be used. Since the measurement time is different from the internal pressure of the mold (including the residual pressure as the internal pressure of the mold) and changes according to the synchronization rate, a variation coefficient capable of reducing the influence of the change is particularly preferable. The coefficient of variation is The standard deviation divided by the mean.

The controller 70 measures the measurement time deviation for each synchronization rate, thereby obtaining the relationship between the synchronization rate and the measurement time deviation. As such, the controller 70 sets the synchronization rate based on the measurement time deviation. The measurement time is stable, and the material of the molded product is stable.

The smaller the synchronization rate, the larger the measurement time deviation tends to be. It is inferred that the smaller the synchronization rate is, the more the filling state of the molding material in the groove 26 of the screw 20 becomes a loose state, a gap is formed between the molding materials, and the transportation of the molding material becomes unstable.

The controller 70 can set the synchronization rate according to the measurement time deviation and other parameters.

For example, the controller 70 may set the synchronization rate according to the deviation of the measurement time and the deviation of the internal pressure of the mold. The stability of the density of the molded product and the weight of the molded product and the stability of the material of the molded product can be taken into consideration.

The smaller the synchronization rate, the smaller the deviation of the internal pressure of the mold, and the larger the deviation of the measurement time. The deviation of the internal pressure of the mold and the deviation of the measurement time indicate different trends.

Therefore, the controller 70 can set the synchronization rate according to the product of the deviation of the internal pressure of the mold and the deviation of the measurement time, and can set the synchronization rate so that the above-mentioned product becomes the minimum. In addition, the controller may set the synchronization rate according to the above product and other parameters. At this time, the above product may not become the minimum value.

The display device 80 displays various screens under the control of the controller 70. The display device 80 may be constituted by, for example, a touch panel, and may include an operation portion that accepts an input operation and a display portion that displays a screen. The controller 70 displays a screen corresponding to an input operation in the operation section on the display section.

The display device 80 can display the relationship between the internal pressure deviation of the mold (including the residual pressure deviation) and the synchronization rate. This relationship can be displayed in the form of charts and tables. The user can know the relationship between the deviation of the internal pressure of the mold and the synchronization rate.

The display device 80 can display the relationship between the measurement time deviation and the synchronization rate. This relationship can be displayed in the form of charts and tables. Users can know the relationship between measurement time deviation and synchronization rate.

The display device 80 can simultaneously display the relationship between the deviation of the internal pressure of the mold and the synchronization rate and the relationship between the deviation of the measurement time and the synchronization rate. It can be seen that the synchronization rate of the stability of the density of the molded product, the stability of the weight of the molded product, and the stability of the material of the molded product can be taken into consideration.

The display device 80 can display the relationship between the product of the deviation of the internal pressure of the mold and the deviation of the measurement time and the synchronization rate.

The display device 80 can display the synchronization rate set by the controller 70, and can display at least one of the relationship between the deviation of the internal pressure of the mold and the synchronization rate, the relationship between the deviation of the measurement time and the synchronization rate, and the relationship between the product and the synchronization rate. While displaying its synchronization rate.

As mentioned above, although embodiment of injection molding machines etc. were described, this invention is not limited to the said embodiment, Various deformation | transformation and improvement are possible within the range of the summary of this invention described in the patent application range.

For example, the material supply device 60 of the above-mentioned embodiment includes a feed screw 67, but may include a vacuum feeder, and its structure is not particularly limited. The material supply device 60 only needs to be capable of changing the supply speed.

Claims (7)

An injection molding machine comprising: a heating cylinder having a supply port at the rear; a material supply device that supplies a molding material to the supply port; and a screw that rotates the heating cylinder to send the molding material to the heating port. And setting means for setting the forming conditions, the setting means setting the relationship between the rotation speed of the screw and the supply speed of the material supply device based on the deviation of the detected value of the pressure applied to the screw after the end of the measurement process for each shot. The injection molding machine according to item 1 of the scope of patent application, wherein the pressure acting on the screw is measured while the screw is held at the rotation stop position after the measurement process is completed. The injection molding machine according to item 1 or 2 of the scope of patent application, wherein the aforementioned setting means sets the aforementioned relationship based on a deviation of the pressure acting on the screw and a deviation of the measurement time. The injection molding machine according to item 1 or 2 of the scope of patent application, wherein the setting means corrects the relationship using a deviation of the measurement time. The injection molding machine according to item 1 or 2 of the scope of patent application, wherein the material supply device includes: a feed cylinder that houses the molding material; and a feed screw that rotates the feed cylinder to rotate the feed material. The molding material is supplied to the supply port. As the supply speed of the material supply device, the rotation speed of the feed screw is used. As the relationship, the ratio of the rotation speed of the screw to the rotation speed of the feed screw is used. A setting device for an injection molding machine, the injection molding machine includes: a heating cylinder having a supply port at a rear portion; a material supply device that supplies a molding material to the supply port; and a screw that rotates the heating cylinder to rotate the heating cylinder. The molding material is sent to the front. The setting device of the injection molding machine is based on the deviation of the detected value of the pressure applied to the screw after the end of the measurement process for each injection, and sets the rotation speed of the screw and the material supply device. The relationship of supply speed. A method for setting an injection molding machine, the injection molding machine comprising: a heating cylinder having a supply port at a rear portion; a material supply device for supplying a molding material to the supply port; and a screw for rotating the foregoing by rotating in the heating cylinder. The forming material is sent to the front. The setting method of the injection molding machine is to set the rotation speed of the screw and the material supply device according to the deviation of the detected value of the pressure applied to the screw after the end of the measurement process for each injection. The relationship of supply speed.