JP2005096175A - Injection molding machine and injection molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine capable of making the amount of a chip material to be supplied accurate and capable of corresponding to a change in the weight of a molded product with the elapse of time, and an injection molding method. <P>SOLUTION: This injection molding machine A is constituted so that the chip material M is melted in an injection cylinder 31 and injected in a mold 33 to be molded and provided with a storage device 20 for storing the chip material M supplied from a vibration feeder 12 and a load cell 27 for measuring the weight of the chip material M stored in the storage device 20. Further, an upper lid part 24 for stopping the supply of the chip material M to the storage device 20 from the vibration feeder 12 when the measured value of the load cell 27 becomes a target value and a lower lid part 26 for supplying the chip material M of which the weight is measured by the load cell 27 to the injection cylinder 31 from the storage device 20 are provided to the injection molding machine A. Furthermore, a molded product measuring instrument 39 for measuring the weight of the molded product P and a control device 40 for correcting the target value from the average weight of the molded product P are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection molding apparatus and an injection molding method for performing injection molding using a molding material made of a chip material.

Conventionally, when a molding material made of a chip material is injection-molded by an injection molding apparatus equipped with a mold, a fixed amount of chip material is supplied into the injection cylinder from a material supply apparatus equipped with a hopper and a feeder. ing. Then, after being heated and melted in the injection cylinder, it is injected into the molding recess of the mold from the injection nozzle and cooled to be molded into a predetermined shape. In this case, in order to accurately mold the molded product, it is necessary to make the amount of the chip material supplied into the injection cylinder constant. In the conventional injection molding apparatus, the amount of the chip material is controlled by the feeding speed and time of the feeder (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 4-90324

  However, in the conventional injection molding apparatus, the chip material in the hopper becomes coarse and dense, and the amount of the chip material supplied to the feeder may be uneven. For this reason, there has been a problem that an accurate amount of the chip material cannot be supplied only by controlling the feeder feed speed and time. In addition, in injection molding, the weight of a molded product may change over time due to the occurrence of burrs, etc., but the conventional injection molding apparatus cannot cope with such a change in the weight of the molded product. There is also a problem. Furthermore, some conventional injection molding apparatuses use a material supply apparatus that sucks the chip material into the hopper by applying a negative pressure inside the hopper with a pump. According to this, when the chip material in the hopper decreases, there is also a problem that the chip material is hardly dropped from the hopper due to the negative pressure in the hopper, and the amount of the chip material supplied to the injection cylinder is reduced.

  The present invention has been made in order to cope with the above-described problem, and an object of the present invention is to provide an injection molding apparatus that can accurately supply the amount of chip material to be supplied and can cope with a change in the weight of a molded product over time. And providing an injection molding method.

  In order to achieve the above object, the structural feature of the injection molding apparatus according to the present invention is that a molding chip material supplied from a material supply apparatus is melted in an injection cylinder and injected from an injection nozzle. An injection molding apparatus that fills a molding recess of a mold and molds into a predetermined shape, a storage device that temporarily stores a chip material supplied from a material supply device, and a chip material that is stored in the storage device Material measuring device for measuring the weight of the material and material supply for stopping the supply of the chip material from the material supplying device to the storage device when the measured value of the weight measured by the material measuring device reaches a preset target value A stop device and a quantitative supply device for supplying the chip material whose weight is measured by the material measuring device from the storage device to the injection cylinder are provided.

  In the injection molding apparatus of the present invention configured as described above, the weight of the chip material is measured instead of controlling the supply amount of the chip material according to the speed and time of supplying the chip material unlike the conventional injection molding apparatus. A material measuring device is provided so that the weight of the chip material actually used for injection molding can be measured. Therefore, even if the chip material to be supplied is coarse or dense, or even if the speed and time at which the chip material is supplied are uneven, the chip material is always supplied to the injection cylinder by a fixed amount.

  At that time, the supplied chip material is temporarily stored in a storage device according to a preset target value, and its weight is actually measured by the material measuring device, and then supplied to the injection cylinder. In addition, the target value in this case is the chip material that is finally stored in the storage device if the supply of the chip material is stopped when the weight of the chip material supplied to the storage device reaches the target value. This amount is a value set based on the calculation that an appropriate amount (material set value described later) required for one injection molding is obtained.

  Further, other structural features of the injection molding apparatus according to the present invention are based on the molded product measuring device for measuring the weight of the molded product molded by the mold, and the weight of the molded product measured by the molded product measuring device. Correction means for correcting the target value of the material to be charged.

  In the injection molding apparatus of the present invention configured as described above, the weight of the molded product is measured by the molded product measuring device, and the target value of the amount of chip material supplied is sequentially corrected based on the measured value. That is, when the weight of the molded product becomes larger than the (input) target value, correction is performed to increase the target value in accordance with the weight of the molded product. Further, when the weight of the molded product becomes smaller than the (input) target value, correction is performed to reduce the input target value in accordance with the weight of the molded product. Therefore, the amount of storage inside the molding machine provided in the injection molding apparatus can be fixed and stable molding can be performed.

  Further, another structural feature of the injection molding apparatus according to the present invention is that the material supply stop device is configured by an openable upper lid provided on the upper portion of the storage device, and the quantitative supply device is That is, it is composed of an openable lower lid provided at the bottom.

  According to the injection molding apparatus configured as described above, when the chip material is supplied from the material supply device to the storage device with the upper lid portion opened, and the weight of the chip material measured by the material measurement device reaches the target value. The supply of the chip material from the material supply device can be stopped and the upper lid portion can be closed. Then, by opening the lower lid portion, an appropriate amount of chip material can be supplied to the injection cylinder. In this case, there is a slight error between the tip material actually supplied to the injection cylinder and the target value. This error is caused by the material measuring device actually measuring the weight of the tip material stored in the storage device. Since it can be obtained, the input amount of the chip material is corrected once every several cycles.

  Further, another structural feature of the injection molding apparatus according to the present invention is that a shutter is provided between the quantitative supply apparatus and the injection cylinder, and the molten molding material is injected in the injection cylinder. This is because the supply of new chip material is stopped. According to this, in the injection cylinder, it is possible to prevent the chip material from being supplied and melted at an unintended timing and fixed to the injection screw or the like.

  The structural feature of the injection molding method according to the present invention is that the molding chip material supplied from the material supply device is melted in the injection cylinder and injected from the injection nozzle to fill the molding concave portion of the mold. An injection molding method for molding into a predetermined shape, a material measurement step for measuring the weight of the chip material supplied from the material supply device, and a target in which the measured value of the weight measured by the material measurement device is set in advance A material supply stop step for stopping the supply of the chip material from the material supply device when the value is reached, and a quantitative supply step for supplying the chip material supplied from the material supply device to the injection cylinder . In this case, the injection molding method includes a molded product measuring step for measuring the weight of a molded product molded with a mold, and a target for correcting the target value based on the weight of the molded product measured in the molded product measuring step. And a value correction step.

  In the injection molding method of the present invention configured as described above, the weight of the chip material supplied from the material supply device is measured, and when the weight reaches the target value, the supply of the chip material from the material supply device is stopped. The chip material having a weight corresponding to the target value is supplied to the injection cylinder. Therefore, a certain amount of chip material can be supplied to the injection cylinder, and stable injection molding can be performed. Further, since the target value for determining the weight of the chip material supplied to the injection cylinder is appropriately corrected based on the weight of the molded product, the weight of the molded product to be molded becomes an appropriate value.

  Further, other structural features of the injection molding method according to the present invention include a material actual measurement step for measuring in advance the weight of the chip material supplied to the injection cylinder in the quantitative supply step, and a material actual measurement step for a predetermined number of injection moldings. Accumulate the difference between the measured value of the measured chip material weight and the set value (material set value) of the weight of the chip material supplied for one injection molding, and set it at the next injection molding. A correction amount supplying step of setting a target value based on a value obtained by adding a cumulative value to the value and supplying a chip material having a weight measured in the material measuring step to the injection cylinder based on the target value. is there.

  In the injection molding method of the present invention configured as described above, when a predetermined error occurs in the total value of the weights of chip materials used in a predetermined number of times (for example, about 5 to 10 times) of injection molding, At the time of injection molding, a process for canceling the error is performed. That is, the difference between the ideal supply amount of the chip material used for the predetermined number of injection moldings (material set value × predetermined number) and the total measured value of the weight of the chip material for the predetermined number of times actually measured by the material actual measurement step is In the injection molding, by using the chip material corresponding to the value added or subtracted from the material set value, the supply amount for a predetermined number of times plus one can be made constant. As a result, it is possible to know the variation of the chip material supplied in each cycle where the predetermined number of times plus one is one cycle.

  Further, another structural feature of the injection molding method according to the present invention is that the target value correction step obtains an average value of the measurement values measured in the molded product measurement step in the predetermined number of injection moldings, and is based on the average value. This is to correct the target value.

  In the injection molding apparatus of the present invention configured as described above, an average weight of a molded product molded by a predetermined number of times (for example, about 100 to 200 times) is obtained, and a target value is set based on this average value. Processing is performed. In this case, the target value may be set using the average value as the material set value as it is, but the target value may be set in consideration of the yield and the like. According to this, even if the weight of the molded product changes depending on the state of the injection molding apparatus, etc., the target value is corrected according to the change, so the weight of the molded product is appropriate for the current situation. It is controlled to become a value.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a main part of an injection molding apparatus A according to the present invention. The injection molding apparatus A melts the material supply device 10, the storage device 20 that temporarily stores the magnesium chip material M supplied from the material supply device 10, and the chip material M supplied from the storage device 20. And a molding machine 30 for molding.

  The material supply device 10 includes a supply hopper 11 and a vibratory feeder 12. The supply hopper 11 is formed in a funnel shape having a large upper end surface and a small lower end opening, a material supply hose is connected to the ceiling surface, and a suction hose (not shown) on the upper side of the side surface. ) Is connected. The other end of the material supply hose is positioned in a drum can in which the chip material M is accommodated, and the other end of the suction hose is connected to a pump. Therefore, by operating the pump, the chip material M in the drum can be sucked and taken into the supply hopper 11, and a predetermined amount of the chip material M is stored in the supply hopper 11.

  The vibratory feeder 12 is formed in a bowl shape, and conveys the tip material M falling from the lower end opening of the supply hopper 11 forward (rightward in FIG. 1) by vibrating. The vibratory feeder 12 vibrates by reciprocating between an upper front side and a lower rear side, and the vibration causes the chip material M to move forward and forward. The vibratory feeder 12 can control the strength of the vibration.

  The storage device 20 is for temporarily storing the chip material M conveyed from the vibratory feeder 12 without directly supplying it to the molding machine 30 and measuring the weight thereof. Two storage hoppers 21 and 22 that are formed to be tapered and have an upper end opening that has a large diameter are stacked one above the other. An upper lid portion 24 that opens and closes a passage in the storage hopper 21 by rotating between a horizontal posture and a downwardly inclined posture around the rotation shaft 23 is provided in the upper side portion inside the storage hopper 21. It has been.

  A lower lid portion 26 that opens and closes a passage in the storage hopper 22 by rotating between a horizontal posture and a downwardly inclined posture around the rotation shaft 25 is provided at a lower side portion inside the storage hopper 22. ing. The storage hopper 22 is provided with a load cell 27 for measuring the weight of the chip material M stored therein, and the measured value of the load cell 27 is displayed on the weighing indicator 28.

  The molding machine 30 includes an injection cylinder 31, an injection nozzle 32 provided at the tip of the injection cylinder 31, and a mold 33. A material receiving portion 31 a for taking in the chip material M falling from the storage hopper 22 is provided on the upper portion of the injection cylinder 31. A screw and a heater (not shown) are provided inside the injection cylinder 31. For this reason, the chip material M taken into the injection cylinder 31 via the material receiving portion 31a is melted by the heating of the heater, and the screw moves toward the mold 33, so that the chip material M enters the mold 33. It is injected into the formed recess 33a.

  The mold 33 includes a fixed mold 34 and a movable mold 35. A spool bush 36 is provided at the center of the fixed mold 34 as shown in FIG. 2, and the molten material passes through the spool bush 36. In addition, a spool forming hole 36a for forming a spool portion of a molded product formed by injection molding is provided. The spool forming hole 36a communicates with the forming recess 33a through a runner forming hole 35a formed at the boundary surface between the fixed mold 34 and the movable mold 35. In addition, a nozzle touch bush 37 having heat insulating properties surrounded by a heat insulating material 37 a is attached to a portion of the fixed mold 34 on the injection nozzle 32 side. The nozzle touch bush 37 is attached such that the tip end portion of the injection nozzle 32 is always in contact, and a coil-shaped heater 32 a is attached to the outer peripheral surface of the tip portion of the injection nozzle 32.

  A cooling water passage 38 for cooling the spool bush 36 is provided in the vicinity of the periphery of the spool formation hole 36 a in the spool bush 36 of the fixed die 34. By configuring the molding machine 30 in this way, continuous touch molding (injection molding performed in a state where the injection nozzle 32 is always in contact with the fixed mold 34) can be performed in a good state.

  The injection molding apparatus A also includes a molded product measuring device 39 for measuring the weight of the molded product P molded by the molding machine 30 and a control device 40 for controlling each device included in the injection molding device A. Yes. When the molded product P is molded by the molding machine 30 and the mold 33 is opened, the molded product P is taken out of the mold 33 and conveyed to the molded product measuring device 39 by a robot (not shown). Then, after the weight is measured by the molded product measuring device 39, the molded product P is transported to a place for the next step by a transport device (not shown).

  The control device 40 includes a CPU, a ROM, a RAM, various circuits, and the like. An operation unit (not shown) for opening and closing the upper lid portion 24 and the lower lid portion 26, a weighing indicator 28, a molding machine 30, and a molding device. It is connected to the product measuring device 39 via each wiring. That is, the control device 40 activates or stops the vibratory feeder 12 and controls the strength of the vibration. Then, the chip material M is supplied to the storage device 20 by the operation of the vibration type feeder 12.

  Further, when the measurement value of the load cell 27 indicated by the weighing indicator 28 reaches the target value set based on the weight (material set value) of the chip material M used for one injection molding, the control device 40 In addition, the vibratory feeder 12 is stopped and the upper lid portion 24 is closed. And the lower cover part 26 is opened by the material supply command from the molding machine 30, and the chip material M in the storage hopper 22 is dropped into the injection cylinder 31. Moreover, the lower cover part 26 is closed after material supply.

  Further, the control device 40 performs an operation of summing the weight of the chip material M measured by the load cell 27, for example, five times. Then, the difference between the total value and the value of the material set value × 5 is obtained, and at the time of the next injection molding, a target value is set based on a value obtained by adding or subtracting the difference obtained by calculation from the material set value, Control is performed to supply the chip material M in accordance with the target value. Further, the control device 40 obtains the weight of a predetermined number of the molded products P measured by the molded product measuring device 39, for example, the average value of the weight of 100 products. And control which changes a target value based on the average value is performed.

  When the molded product P is injection molded using the injection molding apparatus A configured as described above, first, the power switch is turned on and the start button (both not shown) is turned on to perform injection. The operation of the molding apparatus A is started. As a result, the lower lid portion 26 is closed, the upper lid portion 24 is opened, and the vibratory feeder 12 starts to vibrate. Then, the chip material M falling from the supply hopper 11 onto the upper surface of the vibratory feeder 12 is sequentially transferred to the storage device 20 side, passes through the storage hopper 21 from the tip of the vibratory feeder 12 and falls into the storage hopper 22. To do.

  The weight of the chip material M accumulated in the storage hopper 22 is measured by the load cell 27, and when the weight reaches a target value, the conveyance of the chip material M by the vibratory feeder 12 is stopped. At that time, the upper lid portion 24 is closed, and the weight of the chip material M finally stored in the storage hopper 22 is measured by the load cell 27. The measured value is stored in the RAM of the control device 40.

  Subsequently, after injection molding by the molding machine 30, the lower lid portion 26 is opened by a material supply command, and the chip material M in the storage hopper 22 passes through the material receiving portion 31a and is filled into the injection cylinder 31. Then, the screw in the injection cylinder 31 moves and injection molding is performed. At that time, the chip material M supplied into the injection cylinder 31 is melted by the heating of the heater. Further, the chip material M is prevented from entering the injection cylinder 31 during the injection molding.

  When the molded product P is molded, the mold 33 is opened, and the molded product P is conveyed to the molded product measuring device 39 by the robot and the weight is measured. The measured value is stored in the RAM of the control device 40. During the injection molding, the next chip material M is conveyed into the storage device 20, and when the screw is retracted, the lower lid portion 26 is opened by a material supply command from the molding machine 30, and the chip Material M is fed into the injection cylinder 31. In this way, the supply cycle of the chip material M and the injection molding cycle are sequentially performed in accordance with a preset program.

  When the number of times of this injection molding becomes 5, for example, the material set value is 100 g, and the weight of the supplied chip material M is 100.1 g, 100.2 g, 100.1 g, 100.2 g, respectively. If it is 100.1 g, the weight (material set value) of the chip material M supplied in the next injection molding is 99.3 g. In this case, the target value is set to a value slightly smaller than 99.3 g. As a result, the total weight of the chip material M used in each cycle is the same, with six injection moldings taken as one cycle.

  When the number of injection moldings is 100, for example, if the material input target value of the molded product P is 99.8 g and the average weight of 100 molded products P is 99.7 g, Correction is performed so that the target value is set smaller by 0.1 g than the value set during the 100 injection moldings. If the average weight of the 100 molded products P is larger than the material input target value, correction is performed to increase the target value accordingly. Thereby, the storage amount of the chip material M inside the molding machine 30 can be kept constant. This correction is also corrected again based on the average weight of the molded product P obtained by the next 100 injection moldings, and this is repeated.

  As described above, in the injection molding apparatus A according to the present embodiment, the amount of the chip material M supplied to the injection cylinder 31 is controlled by directly measuring the weight of the chip material M with the load cell 27. Therefore, even if the chip material M to be supplied is coarse or dense, or the transport speed and transport time of the vibratory feeder 12 are uneven, the chip material M is always supplied to the injection cylinder 31 by a fixed amount. . Further, in this injection molding apparatus A, the target value of the supply amount of the chip material M is sequentially corrected based on the average value of the weights of the molded articles P that have been molded.

  Further, in the injection molding apparatus A, the yield of the chip material M is improved because the molding machine 30 is used for performing the injection molding in which the injection nozzle 32 is always in contact with the fixed mold 34 side. For this reason, unevenness generated in the amount of the used material is reduced, and the correction of the target value and the like described above has a great effect and enables accurate injection molding.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate. For example, in the above-described embodiment, the chip material M is magnesium, but the material used for the chip material M is not limited to this, and may be a metal chip such as aluminum or titanium, or a resin material. Further, a screw feeder can be used in place of the vibratory feeder 12, and another weighing device can be used in place of the load cell 27. Furthermore, instead of the molded product measuring device 39, a measuring device such as a load cell may be provided in the robot itself so that the weight can be measured when the molded product P is conveyed. Further, the structure of other parts, the correction method of the target value, and the like can be changed within the technical scope of the present invention.

It is a schematic block diagram which shows the principal part of the injection molding apparatus by one Embodiment of this invention. It is sectional drawing which shows the connection part of an injection nozzle and a metal mold | die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Material supply apparatus, 11 ... Supply hopper, 12 ... Vibrating feeder, 20 ... Storage apparatus, 21, 22 ... Storage hopper, 24 ... Upper cover part, 26 ... Lower cover part, 27 ... Load cell, 30 ... Molding machine, 31 DESCRIPTION OF SYMBOLS ... Injection cylinder, 32 ... Injection nozzle, 33a ... Molding recessed part, 33 ... Mold, 34 ... Fixed mold, 35 ... Movable mold, 39 ... Molded article measuring apparatus, 40 ... Control apparatus, A ... Injection molding apparatus, M ... Chip Material, P ... molded product.

Claims (8)

An injection molding apparatus that melts a molding chip material supplied from a material supply apparatus in an injection cylinder and injects it from an injection nozzle to form a predetermined shape by filling a molding concave portion of the mold. ,
A storage device for temporarily storing the chip material supplied from the material supply device;
A material measuring device for measuring the weight of the chip material stored in the storage device;
A material supply stop device for stopping the supply of the chip material from the material supply device to the storage device when the measured value of the weight measured by the material measurement device reaches a preset target value;
An injection molding apparatus comprising: a quantitative supply device that supplies the chip material, the weight of which is measured by the material measuring device, from the storage device to the injection cylinder. A molded product measuring device for measuring the weight of a molded product molded by the mold;
The injection molding apparatus according to claim 1, further comprising: a correcting unit that corrects the target value based on a weight of the molded product measured by the molded product measuring apparatus.   The material supply stop device is configured by an openable / closable upper lid portion provided at an upper portion of the storage device, and the quantitative supply device is configured by an openable / closable lower lid portion provided at a lower portion of the storage device. The injection molding apparatus according to claim 1 or 2.   A shutter is provided between the quantitative supply device and the injection cylinder, and the supply of new chip material is stopped while the molding material melted in the injection cylinder is being injected. The injection molding apparatus according to any one of 1 to 3. An injection molding method in which a molding chip material supplied from a material supply device is melted in an injection cylinder and injected from an injection nozzle to fill a molding concave portion and mold it into a predetermined shape. ,
A material measurement step of measuring the weight of the chip material supplied from the material supply device;
A material supply stop step of stopping the supply of the chip material from the material supply device when the measured value of the weight measured by the material measurement device reaches a preset target value;
An injection molding method comprising: a quantitative supply step of supplying the chip material supplied from the material supply device to the injection cylinder. A molded product measuring step for measuring the weight of the molded product molded by the mold;
The injection molding method according to claim 5, further comprising a target value correcting step of correcting the target value based on a weight of the molded product measured in the molded product measuring step. A material measurement step for measuring in advance the weight of the tip material supplied to the injection cylinder in the quantitative supply step;
Accumulating the difference between the measured value of the weight of the chip material measured in the material actual measurement step in a predetermined number of injection moldings and the set value of the weight of the chip material supplied for one injection molding, and the next injection At the time of molding, the target value is set based on a value obtained by adding the cumulative value to the set value, and the chip material having a weight measured in the material measuring step is supplied to the injection cylinder based on the target value. An injection molding method according to claim 5 or 6, further comprising a correction amount supplying step. 8. The target value correcting step obtains an average value of measured values measured in the molded product measuring step in a predetermined number of injection moldings, and corrects the target value based on the average value. The injection molding method described in 1.

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