JP4526542B2 - Nozzle movement control method in metal forming machine - Google Patents

Description

  The present invention relates to a nozzle movement control method in a metal molding machine in which the tip of a heated nozzle is brought into contact with a cooled mold and a molten metal material is injected and filled from the nozzle into the mold.

In a conventional molding machine that melts and melts low melting point metals such as magnesium, aluminum, and zinc or their alloys into the mold, the molten metal leaks from the nozzle opening when the nozzle is moved backward from the mold. Is prevented by nozzle temperature control.
JP 2001-79653 A (page 4, FIG. 1).

  In the above prior art, the heating means is arranged on the outer peripheral surface of the nozzle arranged on the front end side of the injection unit, and the temperature measuring bodies are arranged on the nozzle front end side and the rear end side, respectively, across the heating means, The stroke from the injection stroke after the injection unit is advanced and the nozzle touches the mold to the reverse of the injection unit is detected by the temperature sensor at the rear end side of the nozzle, and in the other strokes, the nozzle tip side is detected. The temperature of the nozzle is controlled by heating control of the heating means so that the temperature is detected by a temperature measuring body.

  In such a conventional technique, since the entire nozzle is heated by the heater, it is not possible to control the temperature of only the nozzle tip, and the formation of a solid plug (cold plug) at the time of nozzle contact is controlled by heating the heater. Therefore, it is necessary to correct the temperature decrease by heating output with a heater during this period, which has a problem in energy consumption. Two different temperature settings are made for the heater. However, since the heater is provided at the rear of the nozzle tip where the solid plug occurs, the efficiency at the tip is poor, and the solid plug is softened before the injection starts. There is also a problem that a solid plug cannot be efficiently formed when the nozzle moves backward.

  The present invention has been conceived in order to solve the above-described conventional problems. The object of the present invention is to provide a nozzle before the start of injection by a temperature control means provided at the tip of the nozzle separately from the heater for keeping the nozzle warm. It is possible to efficiently soften the solid plug at the tip and to form a solid plug when the nozzle moves backward, and perform nozzle advance control and retract control at the nozzle tip temperature, thereby leaking molten material from the nozzle (nose sagging). It is an object of the present invention to provide a nozzle movement control method in a new metal forming machine that can prevent the above-mentioned problem.

According to the present invention, the nozzle is provided with a heat retaining heater and temperature control means for the nozzle tip where the metal material remains as a solid plug by contact with the cooled mold, and the temperature of the nozzle tip The temperature of the nozzle body can be individually detected and controlled, and the temperature of the nozzle tip can be varied by the temperature control means. The nozzle tip kept at the melting maintenance temperature is brought into contact with the mold, and the nozzle nozzles a molten metallic material then injected and filled into a mold, in metal forming machine to form a solid plug until nozzle retraction after metering stroke, retracted from the mold after weighing stroke that due to the temperature control means from the the heating of the tip, to set the delay time by a timer that operates from any position before the mold clamping step is completed, starts after expiration of the delay time, the temperature of the nozzle tip at the standby position Comparing with the set softening temperature of the plug, if the calculated value is within the allowable range where the solid plug does not melt and leak, allow the nozzle to advance, and if outside the allowable range, wait until it reaches the allowable range. The nozzle is allowed to advance.

  The heating of the nozzle tip by the temperature control means sets a delay time by a timer that operates from an arbitrary position before the mold clamping process, starts after the delay time elapses, and after the nozzle contact, the plug softening peak temperature It is controlled to reach to.

  Further, before the nozzle moves backward from the mold after the weighing step, the temperature control means compares the nozzle tip temperature with a preset plug formation temperature, and the calculated value is within the allowable range of the plug formation temperature. If the nozzle tip is allowed to move back from the mold while maintaining the temperature, the nozzle tip temperature is adjusted so that the nozzle is within the allowable range, and the nozzle is allowed to move back after reaching the allowable range. It is.

  In this invention, the temperature of the nozzle tip can be controlled within the temperature range between the solidus temperature and the liquidus temperature by the temperature control means, so that the formation and maintenance of the solid plug and heating softening can be performed efficiently, which is required for heating the nozzle. Since power consumption can be suppressed, the molding cost can be reduced. In addition, since the actual temperature of the nozzle tip and the set temperature can be compared and calculated, both the forward movement of the nozzle and both forward movement and backward movement can be controlled. Therefore, even if the nozzle needs to be retracted every molding cycle, the operation can be performed safely.

  FIG. 1 shows an embodiment of a metal forming machine that can adopt the nozzle forward and backward control method of the present invention. An injection mechanism 10 has a nozzle tip 12 at the tip of a cylinder having a heating means 11 on the outer periphery. A measuring tube 13 connected to the nozzle port is formed in the inside thereof by a reduced diameter, and a melting cylinder 17 in which a feeding device 15 having a sealing hopper 14 is connected to a material charging port 16 at the upper part of the cylinder, and a rear end Is connected to the piston rod of the injection cylinder 18, and is provided in the melting cylinder 17 from the closed rear end of the cylinder, and includes an axial plunger 20 in which the injection head 19 at the tip is inserted into the measuring chamber 13 so as to be able to advance and retract. Has been.

  The injection mechanism 10 is installed on a sliding plate 27 on the machine base 26 together with the hot runner block 21. The hot runner block 21 is connected to an internal hot runner 22 and has a nozzle 23 for injection projecting on the front surface. The nozzle tip 12 is in airtight contact with the gate of the hot runner 22 to The support base 25 is inclined. Further, a hydraulically operated nozzle contact device 28 is connected to the hot runner block 21 on the machine base 26, and the injection mechanism is moved by the forward / backward movement of the sliding plate 27 by the expansion / contraction operation of the nozzle contact device 28. 10 is configured so as to move forward and backward with the hot runner block 21 with respect to the mold 24 of the mold clamping device (not shown), and the tip surface of the nozzle 23 is in contact with or separated from the sprue gate 24a of the mold 24. .

  As shown in FIG. 2, a heater 29 for heat insulation using a band heater or the like is provided around the outer periphery of the injection nozzle 23 as shown in FIG. Further, a temperature control means 30 such as an induction heater or a resistance heater is provided at the tip of the nozzle where the metal material remains as the solid plug 31, and a thermocouple or the like is provided between the heaters 29 and inside the tip of the temperature control means 30. Are embedded so that the temperatures of the nozzle body and the nozzle tip can be individually detected and controlled.

  FIG. 4 shows a molding cycle of the metal material used in the present invention, and the mold clamping process consists of high speed mold clamping, low speed / low pressure mold clamping, and high pressure mold clamping as shown in FIG. The process consists of a process of clamping the mold 24.

  Further, in the injection stroke, the hot runner block 21 is moved forward together with the injection mechanism 10 by the extension operation of the nozzle abutting device 28, the stroke in which the tip surface of the nozzle 23 comes into contact with the sprue gate 24a of the mold 24, and the injection plunger 20 is injected. The cylinder 18 is driven to move forward to perform injection (filling / holding pressure). After holding the pressure, the mold clamping device side shifts to the cooling stroke, and the injection mechanism side shifts to the metering stroke.

  The material is metered by moving the injection head 19 which has advanced the metering chamber 13 and pushed out the molten material by the forward movement of the plunger 20 back to the retreat setting position by the plunger 20. At the same time, the molded product is cooled in the mold 24. The nozzle 23 having the nozzle tip in contact with the gate 24a is also affected by this cooling, but the nozzle 23 is maintained at the melting temperature, so it does not reach the entire nozzle, and only the nozzle tip is significantly affected. As the tip temperature decreases to the solid phase temperature of the metal material, a solid plug in which the melted material (not shown) remaining in the nozzle cools and solidifies in the tip to close the nozzle port. 31 is formed.

  By forming the solid plug 31, in the measuring chamber 13 communicating with the nozzle 23 via the hot runner block 21, when the injection head 19 moves backward, intake air from the nozzle port is blocked, and therefore the inside of the measuring chamber 13 is negative. As a result, the molten material accumulated in the cylinder is sucked from the gap between the injection heads 19 and flows into the measuring chamber 13 so that a set amount of material can be measured.

  After the measurement is completed, the nozzle 23 is retracted and separated from the mold 24. This is because if the nozzle contact is continued, the cooling of the nozzle tip progresses, and the solid plug 31 becomes a tightly sealed plug, which adversely affects the injection. The heat transfer from the mold side is cut off. However, even after the nozzle 23 is released, it is necessary to maintain the solid plug 31 so as not to affect the injection. Therefore, the temperature control means 30 maintains the temperature. In the mold clamping device side, the process proceeds to the mold opening process, and the molded product is taken out.

  The formation and melting temperature of the solid plug 31 varies depending on the type of metal or alloy used as the molding material. For example, an AZ91D alloy, which is an Mg-Al-based or Mg-Al-Zn-based alloy and is used as a general magnesium alloy molded product, has a liquidus temperature of about 595 ° C and a solidus temperature of about 450 ° C. . Therefore, when a molded product is injection-molded with such a metal material, the nozzle body excluding the tip is heated by the heater 29 set at around 600 ° C. to maintain the temperature of the molten metal flowing in the nozzle. The tip portion can be set to a temperature of about 500 ° C. to about 600 ° C. by the temperature control means 30 so that the solid plug 31 can be maintained and melted at the time of injection.

  The nozzle temperature at the time of injection molding is set to the melt maintenance temperature as a whole including the nozzle tip, but after injection filling, the temperature of the temperature control means 30 is set to around 500 ° C., and the nozzle tip is the mold The solid plug 31 is easily formed by heat transfer from 24. As a result, the nozzle tip temperature decreases to the solidus temperature with the passage of time, so that temperature is compared with the preset plug formation temperature before the nozzle retracting operation, and the calculated value is the allowable plug formation temperature. If it is within the range, nozzle retreat from the mold 24 after the measurement is completed is allowed, and if it is out of the allowable range, the nozzle is kept in contact so that the temperature is adjusted and then the nozzle retreat is allowed. To do.

  The temperature tolerance of the nozzle tip varies depending on the metal material, but at least the solid plug 31 does not cause a nose dripping even if the nozzle moves backward and leaves the mold 24, around ± 5 to 10 ° C. It is desirable to make it. The reason for this is that if the nozzle temperature is too high, nose sagging will occur, and if the nozzle temperature is too low, the solid plug 31 will become too hard and adversely affect injection molding.

  As described above, when the nozzle retreat is allowed from the temperature of the nozzle tip, the temperature control is automatically generated during the molding cycle, so the risk of nasal dripping from the nozzle is low. Then, even during temperature heating, an operator may inadvertently perform a movement operation for retreating the nozzle, which may cause a nose sagging from the nozzle, which may be dangerous.

  This can be prevented by providing the same safety means as in automatic operation. FIG. 5 shows an example of this, and when the operator turns on the nozzle retraction SW, the retreat signal is detected from the nozzle retraction operation control unit, and the temperature of the nozzle tip is detected. If the nozzle temperature is not within the allowable temperature range, adjust the temperature so that it is within the allowable range, and when the nozzle temperature is within the allowable range, issue a signal to the nozzle reverse operation control unit, from the nozzle reverse operation control unit, A nozzle retreat permission signal is output so that the nozzle retreat operation can be performed. As a result, even if the operator carelessly moves the nozzle back, the nozzle tip is controlled to a temperature at which the nose sag does not occur, and the nozzle moves backward to ensure safety.

  When the metering stroke is completed and the nozzle is retracted to stand by at a position away from the mold, the mold clamping device starts the mold closing stroke and shifts to the mold clamping stroke. In accordance with this stroke, the nozzle abuts on the mold 24, but before that, the nozzle tip is heated by the temperature control means 30 to soften the solid plug 31, and the mold is injected from the nozzle tip by the injection pressure. It needs to be pushed to the side. However, when the plug softening peak temperature reaches before the nozzle contact, the solid plug 31 melts and leaks from the nozzle opening, and nose dripping occurs. Therefore, in order to prevent this, the temperature of the nozzle tip is set in advance. Comparing with the softening temperature of the plug, if the calculated value is within an allowable range where the solid plug does not melt and leak, the nozzle is allowed to advance. When it is out of the allowable range, it waits until the allowable range is reached, and then allows the nozzle to advance.

In addition, it is necessary to set the heating start timing in accordance with the nozzle contact stroke. The heating timing of the nozzle tip by the temperature control means 30 is not only at the start of nozzle advancement but before the end of the mold clamping process, for example, before high-speed mold clamping (mold closing stroke) or before high-pressure mold clamping (mold clamping stroke) . A delay time is set by a timer that operates from the desired position, and as shown in FIG. 3, it is preferable to start after the delay time elapses and control to reach the softening peak temperature after nozzle contact.

  FIG. 6 is a flowchart of several heating start timings in relation to the operation of the mold clamping device side. During continuous molding, it is only necessary to slightly move away from the mold 24, so that the nozzle contact stroke is short. Therefore, it is preferable to send a heating start signal when reaching the position 2 before high-pressure mold clamping. If it is desired to earn a molding cycle, it is preferable to transmit a heating start signal from position 1 before the high-speed mold clamping prior to that. Since the nozzle position before the start of molding is far away from the mold, it is preferable to send a heating start signal from position 3 in the first cycle. When a heating signal is transmitted, a timer is activated, and heating is started after the timer time is reached, and temperature control in accordance with the molding cycle becomes possible.

  After the end of the nozzle contact, the process shifts to the injection process of the metering material. However, if the heat softening of the solid plug 31 due to the heating of the nozzle tip by the temperature control means 30 is insufficient and hard, the solid plug will 31 is difficult to extrude and becomes an obstacle to injection, or a part of it is injected into the mold as a solid, leading to defects in the molded product or insufficient strength. It is preferable to start by setting a delay time at a position 4 between the start of injection and a timer. As shown in FIG. 3, after the completion of heating after the nozzle contact is confirmed, the timer is activated and the injection stroke is started after a predetermined time has elapsed, so that the nozzle state after the heating is completed is stable, By suppressing variations in the injection stroke, it is possible to stabilize the molding quality.

  The above-described forming process is intended for the metal forming machine illustrated in FIG. 1, but the forming process can be applied to a metal forming machine using an in-line screw type injection device as it is. Therefore, the present invention is applied to the illustrated metal forming machine. It is not limited. As for the temperature of the nozzle tip, both the case where the actual temperature and the set temperature are compared and calculated when necessary, and the case where the actual temperature is detected and compared with the set value when necessary are employed.

1 is a schematic longitudinal sectional side view of an embodiment of a metal forming machine capable of carrying out the method of the present invention. It is a vertical side view of one embodiment of the nozzle. It is a chart figure which shows the delay time of the heating of a nozzle front-end | tip part, and material injection. It is a flow cheat figure of a molding cycle which can carry out the present invention. It is a flowchart figure of nozzle retraction control at the time of manual operation. It is a flowchart figure which shows the heating start timing of a nozzle front-end | tip part, and the injection start timing of material injection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Injection mechanism 12 Nozzle tip 13 Measuring chamber 17 Molten cylinder 19 Injection head 20 Plunger 21 Hot runner block 22 Hot runner 23 Nozzle 24 Mold 24a Gate 28 Nozzle contact device 29 Heater 30 Temperature control means 31 Solid plug 32, 33 Measurement terminal

Claims (3)

The nozzle is provided with a heat retaining heater and a temperature control means for the nozzle tip where the metal material remains as a solid plug by contact with the cooled mold, and the temperature of the nozzle tip and the temperature of the nozzle body are individually set. The temperature of the nozzle tip can be varied by temperature control means, the tip of the nozzle kept at the melting maintenance temperature is brought into contact with the mold, and the molten metal material is transferred from the nozzle to the mold. In a metal molding machine that forms a solid plug between the injection filling and the nozzle retraction after the weighing process,
The heating of the tip of the nozzle retracted from the mold after weighing stroke that by the above-mentioned temperature control means, by a timer that operates from any position before the mold clamping step is completed, the delay time corresponding to the nozzle abutment stroke or the molding cycle Start after the delay time has elapsed, and compare the nozzle tip temperature with the preset plug softening temperature at the standby position , and the calculated value is within the allowable range where the solid plug does not melt and leak. A nozzle movement control method in a metal forming machine, wherein if there is, the nozzle is allowed to advance, and if it is outside the allowable range, the nozzle is allowed to wait until it reaches the allowable range, and then the nozzle is allowed to advance.   Heating of the nozzle tip by the temperature control means sets a delay time by a timer that operates from an arbitrary position before the end of the mold clamping process, starts after the delay time elapses, and reaches the plug softening peak temperature after the nozzle contact. 2. The method of controlling movement of a nozzle in a metal forming machine according to claim 1, wherein control is performed so as to reach the nozzle.   Before retreating the nozzle from the mold after the weighing process, the temperature control means compares the temperature of the nozzle tip with a preset plug formation temperature, and if the calculated value is within the allowable range of the plug formation temperature. Maintaining that temperature, allowing the nozzle to retreat from the mold, and adjusting the nozzle tip temperature to be within the allowable range when it is outside the allowable range, and allowing the nozzle to retreat after reaching the allowable range The nozzle movement control method in the metal forming machine according to claim 1.

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