JP2009248518A - Injection nozzle temperature control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent nozzle clogging and stringiness and to prevent filling failure and appearance defects during injection molding after a suspension period of an injection molding process, even when an injection nozzle and a metallic die are left in contact during the suspension period of the injection molding process. <P>SOLUTION: The set temperature of temperature control of an injection nozzle during the suspension period of an injection molding process is changed to a prescribed set temperature that is higher than the set temperature during the injection molding. As a result, even when the injection nozzle and the metallic die are left in contact during the suspension period of the injection molding process, nozzle clogging and stringiness are prevented during the injection molding after the suspension period, thereby preventing filling failure and appearance defects of a molded article. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a temperature control method for an injection nozzle for injecting resin, according to an injection molding machine that performs resin molding by injection molding.

  When manufacturing various resin molded products such as semiconductor parts, etc., a resin molded product of a predetermined shape is manufactured by injecting molten resin into a mold using an injection molding machine and cooling the resin. ing.

  The molten resin injected and filled into the mold is cooled by releasing heat to the mold during the cooling process, so that the sprue runner part is solidified together with the product part and separated at the nozzle tip when the mold is opened. Therefore, semi-molten or solidified resin (cold slag) is present at the nozzle tip. Further, when the cold slag is solidified, a flow mark or silver stream is generated due to the cold slag. Furthermore, when the solidified state progresses, nozzle clogging may occur and the molded product may become unfilled. Conversely, if the resin at the nozzle tip is still melted, the sprue becomes thread-drawn, and the thread-like resin sticks to the product part, causing an appearance defect in the next shot or being caught in the mold. Troubles that damage the mold occur.

Therefore, the nozzle clogging and appearance defects are suppressed by controlling the temperature at the tip of the nozzle between the production of one resin molded product and the production of the next resin molded product.
Generally, in resin formation using an injection molding machine, the resin is injected into the mold with the mold closed, and after holding and cooling, the mold is opened, and the completed resin molded product is taken out, and the mold is again formed. Resin molded products are continuously manufactured by closing the mold and repeating a series of operations.

Conventionally, during the production of this continuous resin molded product, the temperature of the injection nozzle has been controlled between the manufacturing steps of each resin molded product.
Hereinafter, a conventional injection nozzle temperature control method will be described with reference to FIGS.

  FIG. 6 is a diagram showing a temperature change in the conventional injection nozzle temperature control method during continuous molding, and FIG. 7 is a diagram showing a temperature change in the conventional injection nozzle temperature control method at the start of resin molding. 6 and 7, the horizontal axis indicates the process cycle, and the vertical axis indicates the nozzle temperature.

As shown in FIG. 6, in the conventional temperature control, the injection nozzle is heated after the mold is closed until the injection is started, and the resin in the injection nozzle is solidified to prevent nozzle clogging. (For example, refer to Patent Document 1).
JP-A-9-248847 JP 2001-105615 A

  However, the conventional injection nozzle temperature control method can prevent nozzle clogging during continuous molding, but the next injection operation starts especially when the molding process itself is stopped while the nozzle is in contact with the mold. There was a problem that the solidification further progressed. On the other hand, if the injection nozzle and the mold are separated during the stop and stand by, the resin flows out to the contact surface between the injection nozzle and the mold, and maintenance of the injection nozzle becomes necessary.

  In recent years, in order to improve production efficiency, it is often the case that the resin molding line and the assembly line of the resin molded product are directly connected, and the resin molding line is frequently stopped when the assembly line is stopped. It is starting to happen.

Along with this, when the resin molding process is stopped, a problem that the resin is solidified at the tip of the injection nozzle has frequently occurred.
As shown in FIG. 7, when the injection nozzle is in contact with the mold and is on standby even while the molding is stopped, heat is released to the mold even if the injection nozzle is stopped at a fixed temperature. For this reason, the temperature of the injection nozzle may not be maintained at the set temperature. When the temperature of the injection nozzle is lower than T, the resin in the injection noise is solidified to cause nozzle clogging, and there is a problem that the molded product becomes unfilled in the first molding when the molding process is restarted. It was. Conversely, if the injection nozzle is simply heated, the temperature may become too high, and if the molding process is resumed if the resin becomes too soft, the yarn will remain while molding several molded products. There is a problem that pulling or the like occurs, resulting in poor appearance.

  Furthermore, when controlling the temperature of the injection nozzle during resin molding during continuous molding, the time between resin molding is short and almost constant, so temperature control can be easily performed, but the resin molding is stopped. In this case, the stop time is long and short and is not constant, and the stop time is much longer than that during resin molding. In addition, there is a problem that it is difficult to suppress the solidification of the resin while suppressing defects in stringing and stringing.

  In order to solve the above-described problems, the injection nozzle temperature control method of the present invention can be used after the stop period of the injection molding process even if the injection nozzle and the mold are in contact with each other during the stop period of the injection molding process. An object of the present invention is to prevent nozzle clogging and stringing during injection molding to prevent unfilled molded products and poor appearance.

  In order to achieve the above object, an injection nozzle temperature control method according to claim 1 is an injection nozzle temperature control method for an injection molding machine for forming a molded product by injection molding a resin from an injection nozzle to a mold, During the molding process, temperature control is performed at the first set temperature, a process for detecting a molding stop signal, and a contact between the injection nozzle and the mold when the molding stop signal is detected. The step of automatically changing the temperature for temperature control to a predetermined second set temperature higher than the first set temperature and stopping the molding, the step of detecting a signal for restarting the molding, And a step of returning the temperature for temperature control to the first set temperature when a signal for restarting molding is detected.

  The injection nozzle temperature control method according to claim 2 is characterized in that, in the injection nozzle temperature control method according to claim 1, the second set temperature is 20 ° C. to 40 ° C. higher than the first set temperature.

  The injection nozzle temperature control method according to claim 3 is the injection nozzle temperature control method according to claim 1 or 2, wherein the injection nozzle temperature control method has a plurality of steps when automatically changing to the second set temperature. It is characterized by being raised separately.

  The injection nozzle temperature control method according to claim 4 is the injection nozzle temperature control method according to claim 3, wherein the injection nozzle temperature is constant so that the temperature of the injection nozzle is constant during the molding process and during the molding stop. The second set temperature is raised in a plurality of stages corresponding to the theoretical value of the temperature drop of the injection nozzle when molding is stopped at the first set temperature while being in contact with the mold. And

  The injection nozzle temperature control method according to claim 5 is an injection nozzle temperature control method for an injection molding machine that forms a molded product by injection molding a resin from an injection nozzle to a mold. A step of performing temperature control at a set temperature, a step of detecting a signal for stopping molding, and the first nozzle while keeping the injection nozzle in contact with the mold when the signal for stopping molding is detected. The step of stopping molding while controlling the temperature at a set temperature, the step of detecting a signal for resuming molding, and the temperature for temperature control when detecting the signal for resuming molding is higher than the first set temperature A step of automatically changing to a predetermined second set temperature, a step of maintaining temperature control at the second set temperature until the temperature of the injection nozzle reaches the temperature during the molding step, and the injection nozzle The temperature of the molding The temperature for the temperature control to be a temperature in the extent and having a step resuming the forming back to the first set temperature.

  The injection nozzle temperature control method according to claim 6 is an injection nozzle temperature control method for an injection molding machine that forms a molded product by injection molding a resin from an injection nozzle into a mold. A step of performing temperature control at a set temperature, a step of detecting a signal for stopping molding, and a temperature control is stopped while the injection nozzle and the mold are in contact with each other when a signal for stopping molding is detected. A step of stopping molding, a step of detecting a signal for resuming molding, and a predetermined second setting for controlling the temperature when the signal for resuming molding is detected is higher than the first set temperature. A step of automatically setting the temperature, a step of maintaining temperature control at the second set temperature until the temperature of the injection nozzle reaches the temperature during the molding step, and the temperature of the injection nozzle is the molding step When the inside temperature is reached And having a resume molding by returning the temperature to the temperature control to the first predetermined temperature step.

  The injection nozzle temperature control method according to claim 7 is the injection nozzle temperature control method according to claim 5 or 6, wherein the second set temperature is 20 ° C to 40 ° C higher than the first set temperature. It is characterized by high ℃.

  As described above, even when the injection nozzle and the mold are in contact during the stop period of the injection molding process, molding is performed by preventing nozzle clogging and stringing during injection molding after the stop period of the injection molding process. Unfilled products and poor appearance can be prevented.

  As described above, the injection nozzle is controlled during the stop period of the injection molding process by changing the set temperature of the temperature control of the injection nozzle during the stop period of the injection molding process to a predetermined set temperature higher than the set temperature during the injection molding. Even when the mold is in contact with the mold, nozzle clogging and stringing can be prevented at the time of injection molding after the stop period of the injection molding process to prevent unfilled molded products and poor appearance. it can.

  The injection nozzle temperature control method of the present invention automatically raises the set temperature of the injection nozzle while the injection nozzle and the mold are in contact with each other during the stop period of the injection molding process, and the resin in the injection nozzle is in an appropriate state. By controlling the temperature of the injection nozzle to prevent nozzle clogging and stringing, it is possible to prevent unfilled molded products and poor appearance even in injection molding after the stop period of the injection molding process It is.

Hereinafter, each embodiment will be described in detail with reference to the drawings.
(Embodiment 1)
First, the injection nozzle temperature control method in Embodiment 1 is demonstrated using FIGS. 1-3.

  FIG. 1 is a schematic cross-sectional view for explaining the configuration of an injection molding machine according to the present invention, and is an overall cross-sectional view schematically showing an injection molding machine and a mold for performing a control method of the injection molding machine. FIG. 2 is a diagram showing a temperature change in the injection nozzle temperature control method at the start of resin molding in Embodiment 1, and FIG. 3 is a flowchart for explaining a set temperature changing step in the injection nozzle temperature control method of the present invention.

  As shown in FIG. 1, for example, when the injection molding machine is of a screw / prepa type, the injection apparatus 100 and a pre-plasticizing apparatus 200 for supplying a plasticized molding material to the injection apparatus 100 are formed. A plasticized molding material is injected from the apparatus 100 into the cavity 301 of the mold 300. The injection molding machine is not limited to the screw / prepa type.

  The injection device 100 is driven by a drive unit 3 and a cylinder 1 having a nozzle 11 whose tip is in contact with a mold 300, and the axial direction of the cylinder 1 is closer to the base side (inside the body) than the nozzle 11 inside the cylinder 1. And a driving means 3 for moving the plunger 2 in the axial direction (moving it up and down in FIG. 1). A supply port 12 to which the plasticized molding material from the preliminary plasticizing apparatus 200 is supplied is provided in the middle of the sliding position of the plunger 2 in the cylinder 1.

  The driving means 3 includes a plurality of slide guide shafts 31 extending upward along the axial direction from the base end portion of the cylinder 1, a support base 32 attached to one end of the slide guide shaft 31, and the support base 32. The installed drive motor 33, one end of the screw shaft 34 connected to the drive motor 33 and rotating, and the screw shaft 34 meshes with the screw portion and moves along the slide guide shaft 31 by forward and reverse rotation of the screw shaft 34. And a moving member 35. One end of the moving member 35 is connected to the upper end of the plunger 2 via a load cell 36 as a pressure detector, and the driving force is transmitted to the plunger 2 to move the plunger 2. The load cell 36 functions as a pressure detector for detecting the injection pressure received from the resin (resin pellet) side in the cylinder 1 of the plunger 2. The drive motor 33 is attached with an encoder 37 as a position detector that detects the position of the plunger 2 based on the rotation speed and rotation angle of the screw shaft 34. Instead of providing the encoder 37, a proximal end portion or a distal end portion of the plunger 2 or a position sensor for detecting the position of the moving member 35 may be provided. Reference numeral 5 denotes a control unit that performs drive control of the drive motor 33, and 4 denotes a backflow prevention valve that prevents the resin melt as a molding material from flowing back to the supply port 12. The driving means 3 is not limited to the above configuration, and any configuration may be used as long as the plunger 2 can be moved and controlled to a predetermined position and the resin injection pressure acting on the plunger 2 and the position of the plunger 2 can be recognized. .

  The preliminary plasticizing apparatus 200 includes a hopper 201, a screw 202, and a screw housing 203, and granular resin (resin pellets) as a molding material stored in the hopper 201 is plasticized in the screw housing 203 by the screw 201. The plasticized plastic is sent into the cylinder 1 through the supply port 12 of the cylinder 1.

The cavity 301 is separated into a sprue runner portion 302 and a product portion 304 by a runner gate 303 whose flow path is narrowed.
A heating device (for example, a coil heater) 13 is provided around the nozzle 11 and a thermocouple 14 is provided. The heating device 13 and the thermocouple 14 are connected to the temperature adjusting device 6, and the temperature is controlled by PID control or the like so that the nozzle 11 maintains the set temperature.

  Although not shown, the screw housing 203 and the cylinder 1 are each provided with a heating device (for example, a panel heater) in the same manner as the nozzle 11 and are heated to a predetermined temperature at the time of molding. .

  In the above configuration, the plasticized resin is supplied from the preliminary plasticizing apparatus 200 into the cylinder 1 through the supply port 12, and the plunger 2 is moved to the nozzle 11 side in a state where the plasticized resin is filled in the cylinder 1. Is moved (lowered in this embodiment), one shot of plasticized molding material (resin) is injected into the cavity 301 of the mold 300. Thereafter, the injection pressure is held by the plunger 2 until the resin in the cavity 301 of the mold 300 is solidified. When the resin is solidified, the mold 300 is released, the molded product in the cavity 301 is taken out, the mold 300 is assembled again, and the plunger 2 is moved and held to perform the injection process and the holding process. By repeating the above, the molding operation is repeated.

  When the molding process as described above is stopped, the molding process is performed with the mold 300 and the nozzle 11 in contact with each other in order to prevent the resin as the molding material from flowing out between the mold 300 and the nozzle 11. Stop. In that case, after the mold 300 is released and the molded product in the cavity 301 is taken out, the tip of the nozzle 11 continues to absorb heat, so that the set temperature of the nozzle 11 cannot be maintained. When the temperature of 11 becomes lower than a certain temperature T (see FIG. 2), the resin present at the tip of the nozzle 11 is gradually solidified by the time the molding process is restarted and becomes cold slag.

  Therefore, in the temperature control method for the injection molding nozzle in the present embodiment, as shown in FIG. 2, when the molding process is stopped, the set temperature is automatically increased, and the temperature of the nozzle 11 during the molding stop is set to the nozzle. By keeping the temperature at or above the temperature T at which clogging occurs, the resin in the nozzle 11 is prevented from solidifying and nozzle clogging is prevented, and the molded product is prevented from becoming unfilled. At this time, the set temperature needs to be set to a temperature that is not too high so that the nozzle 11 does not rise too much and appearance defects due to stringing or the like do not occur. For example, when the resin is a general epoxy resin, it is possible to suppress solidification of the resin remaining at the tip of the nozzle 11 while suppressing problems such as stringing by increasing the set temperature by about 20 ° C. to 40 ° C. . Further, when the molding process is resumed, the molding process is resumed after the set temperature is returned to the original set temperature.

The setting temperature changing step will be described with reference to FIG. 3. In FIG. 3, first, it is detected whether or not the forming stops during the forming step of controlling the temperature of the nozzle 11 at the first set temperature (step 1). When molding is stopped upon receiving a molding stop signal from the injection molding machine, the temperature control set temperature of the nozzle 11 is changed from the first set temperature to a second set temperature that is higher by a predetermined temperature (step 2). ). While the molding is stopped, the temperature of the nozzle 11 is controlled at the second set temperature while the mold 300 and the nozzle 11 are in contact with each other. While the molding is stopped, it is detected that molding is resumed by receiving a molding restart signal from the injection molding machine (step 3). When molding is resumed, the temperature control set temperature of the nozzle 11 is set. The temperature is returned to the first set temperature (step 4). Thereafter, the molding process is performed while controlling the temperature of the nozzle 11 at the first set temperature.

As described above, when stopping the molding process, even if the mold and the injection nozzle are held in contact with each other in order to eliminate the need for maintenance at the tip of the injection nozzle, The nozzle set temperature is automatically raised within a predetermined range from the set temperature during the molding process to prevent nozzle clogging and stringing, and even during injection molding after the injection molding process is stopped, Appearance defects can be prevented.
(Embodiment 2)
Next, the injection nozzle temperature control method according to the second embodiment will be described with reference to FIGS.

FIG. 4 is a diagram showing a temperature change in the injection nozzle temperature control method at the start of resin molding in the second embodiment.
As shown in FIG. 4, the temperature control method for the injection molding nozzle in the present embodiment is characterized in that the set temperature is increased stepwise with respect to the temperature control method for the injection molding nozzle in the first embodiment. To do. Further, the set temperature may be raised stepwise so that the temperature rises while suppressing the amplitude of the temperature based on the theoretical value of the temperature change curve accompanying the heat conduction at the tip of the nozzle 11. it can. That is, as shown in FIG. 7, when the injection molding process is stopped while the nozzle 11 is in contact with the mold 300, the temperature of the nozzle 11 gradually decreases while drawing a curve according to the thermal conductivity. The set temperature is automatically changed so as to have a set temperature curve in contrast to this curve or a stepped set temperature change approximated thereto. Thereby, it is possible to maintain a constant temperature while the injection molding is stopped as in the injection molding process.

  Generally, when the set temperature is rapidly increased, the temperature increase of the nozzle 11 is increased with overshoot and undershoot. In this way, since the temperature approaches the set temperature with the amplitude of the temperature, even if the set temperature is raised when the molding process is stopped, the temperature of the nozzle 11 falls below the temperature T at which the resin temporarily solidifies, and the resin remains. Solidification may cause nozzle clogging, or the temperature may rise excessively, resulting in poor appearance, and it may be difficult to perform optimal temperature control, especially the first molded product after resuming the molding process. May cause problems.

  In order to suppress the amplitude of the temperature rise, it is necessary to gradually increase the set temperature based on the theoretical value of the temperature change curve accompanying the heat conduction at the nozzle tip. By suppressing the amplitude of the temperature rise, a constant temperature can be maintained while the injection molding is stopped as in the injection molding process, and the temperature rises or falls too much during the temperature control of the nozzle 11. This can be suppressed, and even the first molded product after resuming molding can prevent unfilling of the molded product and poor appearance.

As described above, when stopping the molding process, even if the mold and the injection nozzle are held in contact with each other in order to eliminate the need for maintenance at the tip of the injection nozzle, By gradually increasing the nozzle set temperature automatically from the set temperature during the molding process to a predetermined temperature, nozzle clogging and stringing can be prevented, and the first injection molded product after the injection molding process is stopped Filling and appearance defects can be prevented.
(Embodiment 3)
Next, the injection nozzle temperature control method according to the third embodiment will be described with reference to FIGS.

FIG. 5 is a diagram showing a temperature change in the injection nozzle temperature control method at the start of resin molding in the third embodiment.
In the temperature control method of the injection molding nozzle in the present embodiment, as shown in FIG. 5, the set temperature is increased in the first embodiment by receiving a molding resumption signal from the injection molding machine. To do.

  During the molding stop period, the temperature of the nozzle 11 is radiated to the mold 300 by continuing the temperature control of the noise 11 at the same first set temperature as that during the injection molding, so that the temperature decreases as shown in FIG. . Here, when a molding resumption signal is received from the injection molding machine, the set temperature is automatically raised to a predetermined second set temperature as in the first embodiment. Thereafter, the temperature control at the second set temperature is maintained until the temperature of the noise 11 rises to the temperature at the time of injection molding, and the temperature of the noise 11 rises so that the resin in the noise 11 has an appropriate softness. When softened, the set temperature is returned to the first set temperature and the injection molding is restarted.

  In this way, the temperature control is performed at a high temperature for a longer period than necessary by increasing the set temperature and softening the resin inside the noise 11 until the injection molding is restarted after the molding restart is instructed. Even if the nozzle 11 is kept in contact with the mold 300 during molding stoppage, nozzle clogging and stringing can be prevented by controlling the temperature so as to soften the resin inside the nozzle 11 before restarting injection molding. It is possible to prevent unfilled and poor appearance of a molded product that has been injection-molded after a stop period of the injection molding process.

  Here, the case where the temperature control is continued at the first set temperature even during the molding stop period has been described. However, the temperature control is also stopped during the molding stop period, and the second set temperature is received after the molding restart signal is received. Then, the temperature of the nozzle 11 is controlled, and when the resin in the noise is softened to an appropriate degree, the set temperature may be returned to the first set temperature and the injection molding may be resumed.

  The present invention can prevent nozzle clogging and stringing to prevent unfilling of molded products and poor appearance, and temperature control of an injection nozzle for injecting resin according to an injection molding machine that performs resin molding by injection molding Useful for methods and the like.

Schematic cross-sectional view for explaining the configuration of the injection molding machine of the present invention The figure which shows the temperature change in the injection nozzle temperature control method at the time of the resin molding start in Embodiment 1 Flow chart for explaining a set temperature changing step in the injection nozzle temperature control method of the present invention The figure which shows the temperature change in the injection nozzle temperature control method at the time of the resin molding start in Embodiment 2. The figure which shows the temperature change in the injection nozzle temperature control method at the time of the resin molding start in Embodiment 3. The figure which shows the temperature change in the injection nozzle temperature control method in the conventional continuous molding The figure which shows the temperature change in the injection nozzle temperature control method at the time of the conventional resin molding start

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Plunger 3 Drive means 4 Backflow prevention valve 5 Control part 6 Temperature regulator 11 Nozzle 12 Supply port 13 Heating device 14 Thermocouple 31 Slide guide shaft 32 Support stand 33 Drive motor 34 Screw shaft 35 Moving member 36 Load cell 37 Encoder 100 Injection device 200 Pre-plasticizing device 201 Hopper 202 Screw 203 Screw housing 300 Mold 301 Cavity 302 Sprue runner 303 Runner gate 304 Product part

Claims (7)

An injection nozzle temperature control method for an injection molding machine that forms a molded product by injection molding a resin from an injection nozzle into a mold,
A step of performing temperature control at the first set temperature during the molding step;
Detecting a signal to stop molding;
When a signal for stopping the molding is detected, the temperature for temperature control is automatically changed to a predetermined second set temperature higher than the first set temperature while the injection nozzle and the mold are kept in contact with each other. A process of stopping molding,
Detecting a signal for resuming molding;
And a step of returning the temperature to be controlled to the first set temperature when a signal for restarting the molding is detected.   2. The injection nozzle temperature control method according to claim 1, wherein the second set temperature is 20 ° C. to 40 ° C. higher than the first set temperature.   3. The injection nozzle temperature control method according to claim 1, wherein when the temperature is automatically changed to the second set temperature, the temperature is raised in a plurality of stages.   The injection nozzle in the case where the molding is stopped at the first set temperature while the injection nozzle and the mold are in contact with each other so that the temperature of the injection nozzle becomes constant from the molding process to the molding stop. 4. The injection nozzle temperature control method according to claim 3, wherein the second set temperature is raised in a plurality of stages corresponding to a theoretical value of temperature drop. An injection nozzle temperature control method for an injection molding machine that forms a molded product by injection molding a resin from an injection nozzle into a mold,
A step of performing temperature control at the first set temperature during the molding step;
Detecting a signal to stop molding;
Stopping the molding while controlling the temperature at the first set temperature while keeping the injection nozzle and the mold in contact with each other when a signal to stop the molding is detected;
Detecting a signal for resuming molding;
Automatically changing the temperature for temperature control to a predetermined second set temperature higher than the first set temperature when detecting a signal for restarting the molding;
Maintaining the temperature control at the second set temperature until the temperature of the injection nozzle reaches the temperature during the molding step;
And a step of restarting molding by returning the temperature to be controlled to the first set temperature when the temperature of the injection nozzle reaches the temperature during the molding step. An injection nozzle temperature control method for an injection molding machine that forms a molded product by injection molding a resin from an injection nozzle into a mold,
A step of performing temperature control at the first set temperature during the molding step;
Detecting a signal to stop molding;
A step of stopping molding by stopping temperature control while keeping the injection nozzle and the mold in contact with each other when a signal to stop the molding is detected;
Detecting a signal for resuming molding;
Automatically setting the temperature to be controlled to a predetermined second set temperature higher than the first set temperature when a signal for restarting the molding is detected;
Maintaining the temperature control at the second set temperature until the temperature of the injection nozzle reaches the temperature during the molding step;
And a step of restarting molding by returning the temperature to be controlled to the first set temperature when the temperature of the injection nozzle reaches the temperature during the molding step.   The injection nozzle temperature control method according to claim 5, wherein the second set temperature is 20 ° C. to 40 ° C. higher than the first set temperature.

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