JP2004188825A - Injection mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection mold in which an operation which is conventionally adjusted by the replacement of a nozzle can simply be performed, instead by a mold, in case an injection loading pressure needs to be adjusted in accordance with the change in the characteristics of a molding material such as a rate of thermosetting reaction whenever a molded product or a material lot is altered and that thus the change in the characteristics can be easily and rapidly dealt with. <P>SOLUTION: This injection mold operates as follows: a flow diversion element 16 of almost the same shape as a sprue 11 of the mold 4 is loosely inserted into the sprue 11 so as to allow the flow diversion element 16 to move to the sprue 11; when shifting the position of the element 16 from the sprue 11, since the length and area of a flow path formed by the inner surface of the sprue 11 and the outer surface of the element 16 are changed, the resistance of the flow path increases and decreases to adjust the injection loading pressure; a drive means 50 for the element 16 receives the input of a drive signal in compliance with the results of a comparison between measurement data on the injection filling pressure and setting data; and thus, the injection loading pressure can be adjusted on real time by shifting the element 16 in the required direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection molding die suitable for injection molding using a thermosetting or thermoplastic synthetic resin material, rubber, a rubber-like elastic material (elastomer), or the like as a molding material.
[0002]
[Prior art]
At the time of injection molding, the molding material self-heats due to injection shear heat in proportion to the injection filling pressure, and a phenomenon occurs in which the temperature of the material injected into the cavity rises. The temperature rise of the material due to the injection heat generated in relation to the injection filling pressure is required for molding of a material in which a curing reaction is accelerated by heat, such as rubber or thermosetting resin. In the case of rubber or rubber, the vulcanization time is shortened, which is advantageous in terms of productivity. On the other hand, when the injection filling pressure is large, the thermoplastic resin material is filled at a high speed so as not to be cooled and solidified in the middle of a mold passage such as a sprue, a runner, a gate, etc. so that the material is not insufficiently filled in the cavity. It is preferred. However, it is not preferable to raise the temperature by the injection filling pressure, because if the temperature is too high, it will cause degradation of the thermoplastic resin itself.
[0003]
That is, in the injection molding of rubber or a thermosetting resin material, it is desired to set the injection filling pressure as high as possible within a range where the material does not scorch (burn the material). On the other hand, in injection molding of a thermoplastic resin material, it is desirable to set the injection filling pressure as low as possible within a range that does not cause insufficient injection filling.
[0004]
For this reason, in the injection molding process, when setting the injection molding conditions, it is necessary to select an optimal nozzle diameter so as to secure a suitable injection speed and injection filling pressure according to the combination of the used material and the mold. It is required, and it is necessary to replace the nozzle with an optimal nozzle diameter for each product to be molded (molded product).
[0005]
This nozzle replacement work may not be possible with the molding die attached to the injection molding machine, and it may be necessary to remove the mold from the injection molding machine and disassemble the mold. . That is, the nozzles are exchanged by performing the mold removing operation and the mold separating operation, the mold assembling operation and the mounting operation are performed again, and the respective operations such as adjusting the molding temperature are sequentially performed. However, these operations are complicated and require a considerable amount of time, and various types of nozzles must be prepared, thus increasing the cost. For this reason, there is an injection molding die described in Patent Literature 1 in order to save the trouble of exchanging the nozzle for each of a plurality of cavities. In this injection mold, a resin flow path is branched from a sprue portion to a gate of each cavity in an injection mold having a three-plate structure using a pinpoint gate for each of a plurality of cavities. A secondary sprue lock pin is provided on the stripper plate side of the runner, with its tip facing the secondary sprue part corresponding to each gate, and the mold is attached to the molding machine. It has a structure arranged so that the position can be adjusted from the outside.
[0006]
[Patent Document 1]
JP-A-11-19975
[Problems to be solved by the invention]
However, in the case of the molding die described in Patent Literature 1, it is necessary to adjust the secondary sprue lock pin for each secondary sprue. This adjustment is performed manually, and since the plurality of secondary sprue lock pins are adjusted, it is difficult to say that the workability has been sufficiently improved. That is, when adjusting a plurality of secondary sprue lock pins, the adjustment may vary, and the flow resistance may be different for each secondary sprue. May occur. Therefore, the secondary sprue lock pin must be adjusted to make the flow resistance equal, but this adjustment operation is complicated and requires skill in some cases.
[0008]
In addition, in the case of injection molding, even if the same molded product is used, the fluidity of the material varies depending on the production lot of the material used. The pressure fluctuates and a desired molded product may not be obtained. Furthermore, in the case of rubber and thermosetting resin, the thermosetting reaction rate and the vulcanization rate also vary for each production lot of the material, and the thermosetting reaction rate is large even if the same injection conditions are set. If the material lot is too large, scorch is generated at the time of injection filling, and if the thermosetting reaction rate is too low, the thermosetting reaction of the molded product may be insufficient, and a molded product of desired quality may not be obtained. . Therefore, in order to ensure the quality of the molded product, the nozzle diameter is changed according to the thermosetting reaction speed for each production lot of the material, as in the case of changing the material used and the mold. That is, the injection filling pressure is changed by changing the nozzle diameter, and as a result, the injection heat generation amount is changed.
[0009]
Further, when the operation time of the injection molding machine is prolonged, there is a possibility that the flow path of the material is worn or the material stays in the flow path. Also in such a case, since the flow path resistance fluctuates, the injection filling pressure may fluctuate. That is, there is a possibility that the injection filling pressure may fluctuate over time, and it is preferable that the fluctuation of the injection filling pressure is constantly monitored even during operation, and adjustments can be made in accordance with the fluctuation.
[0010]
Therefore, the present invention enables the injection filling pressure to be set arbitrarily, and even if the molded product is changed, different materials from different production lots are used when molding the same molded product. It is an object of the present invention to provide an injection mold capable of easily changing the setting of the injection filling pressure and processing a molded product having no variation in quality.
[0011]
[Means for Solving the Problems]
As a technical means for achieving the above object, the injection molding die according to the present invention, the shunt is loosely inserted concentrically into the sprue formed between both sides of the fixed runner and the nozzle touch, The shunt is supported so as to be movable in the axial direction of the sprue, and a driving unit for moving the shunt is provided.
[0012]
By moving the shunt, the positional relationship with respect to the sprue is changed. The flow path of the material for the shunt inserted loosely into the sprue has an annular cross section, and the length of the flow path changes depending on the position of the shunt, and the resistance of the flow path differs. In addition, the sprue is formed by a conical inner surface, and the area of the flow path varies depending on the play insertion position of the shunt, thereby changing the flow path resistance. In other words, by changing the position of the shunt, the same function as in the case where the diameter of the nozzle is changed can be achieved. The injection filling pressure is changed by the change in the flow path resistance, and an injection filling pressure suitable for a molded product can be obtained. In addition, since the movement of the shunt is performed by the driving means, the amount of movement of the shunt can be known by detecting the driving amount of the driving means, for example, the rotation angle when a motor is used. By previously finding the position of the shunt in accordance with the molded product or the material, it is possible to set an optimal flow path resistance for the molded product or the like.
[0013]
According to a second aspect of the present invention, there is provided an injection mold having a three-plate mold structure having a runner split surface and a cavity split surface separately. The runner stripper plate is formed with a through hole passing through the runner stripper plate coaxially with the gate, and the shunt is supported in the through hole so as to be movable in the axial direction of the through hole. And
[0014]
In the case of the three-plate structure, a through-hole can be formed in the runner stripper plate so as to face the opening of the gate communicating with the cavity. Therefore, by providing the shunt movably in the through hole, the opening area of the gate can be changed, and the flow path resistance at the opening of the gate can be changed. Thereby, the injection filling pressure into the cavity can be changed. That is, the injection filling pressure can be adjusted by adjusting the position of the shunt with respect to the opening of the gate. Moreover, it can be adjusted for each gate.
[0015]
According to a third aspect of the present invention, there is provided an injection mold having a three-plate mold structure having a runner split surface and a cavity split surface separately. Drive means for concentrically inserting a sprue shunt into the sprue formed between the two surfaces of the sprue, supporting the sprue shunt in a manner movable in the axial direction of the sprue, and moving the sprue shunt. A runner stripper plate and a through-hole penetrating the runner stripper plate, and a coaxial gate with a gate formed between both surfaces of the runner and the cavity. It is characterized by being supported movably in the axial direction.
[0016]
That is, the shunt is provided at both the sprue and the position facing the gate. Since the increase and decrease of the flow path resistance can be adjusted between the sprue and the opening of the gate, the injection filling pressure can be adjusted to be more optimal.
[0017]
In addition, the injection mold according to the invention of claim 4 includes a pressure detection unit that measures an injection filling pressure during injection molding, and a drive control unit that sends a drive signal to the drive unit. The means has setting data on injection filling pressure according to the molded product, and can input comparison data by an external operation, compares the setting data or comparison data with the detection data, and performs a desired injection filling. A drive signal for moving the shunt is sent to a position corresponding to the pressure, and the driving means operates in accordance with the drive signal to change the movement position of the shunt.
[0018]
When the injection filling pressure is detected by the pressure detecting means, the detection data is sent to the drive control means. In the drive control means, for example, data relating to the optimal injection filling pressure according to the molded product is set as setting data, and the setting data is compared with the detection data. A drive signal is sent so as to move. In response to the drive signal, the drive means is driven to move the shunt. Also, the quality of the molded product such as the occurrence of scorch is checked, and the injection data is adjusted to the injection filling pressure according to the change of the material lot by changing the comparison data by an external operation and changing the drive signal.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an injection mold according to the present invention will be specifically described based on the illustrated preferred embodiments. In this embodiment, an injection molding die suitable for injection molding using rubber as a material is shown.
[0020]
FIG. 1 is a sectional view for explaining a schematic structure of a part of an injection mold and an injection molding machine according to the present invention. A casing 1 is provided with a horizontal extrusion device 2 and a vertical injection cylinder 3. In addition, a mold 4 is arranged below the injection cylinder 3, and a molding material injected from the injection cylinder 3 is supplied into the mold 4.
[0021]
The extruding device 2 includes a cylindrical cylinder portion 21 and a screw 22 rotatably housed therein. A supply port 23 is provided in a part of the cylinder 21, and rubber as a molding material is supplied into the cylinder 21 from the supply port 23. At the front end of the cylinder portion 21, a neck portion 24 is provided with a reduced diameter. In front of the neck portion 24, a check valve 25 in which a valve body 25b is accommodated in an enlarged diameter portion 25a is provided. A communication passage 26 is provided downstream of the check valve 25, and the check valve 25 communicates with the cylinder portion 31 of the injection cylinder 3 via the communication passage 26. This check valve 25 allows the material to flow from the extrusion device 2 to the injection cylinder 3 and prevents the flow in the reverse direction.
[0022]
The communication passage 26 communicates with an injection pot 32 disposed below the cylinder 31. The injection cylinder 3 has a structure in which a plunger 33 is slidably accommodated in a cylindrical cylinder portion 31, and the injection pot portion 32 is provided at a lower end portion. The inner surface of the injection pot portion 32 is formed as a conical inner surface, and a supply path 34 communicates with the lower end. The tip shape of the plunger 33 is formed in a conical shape that matches the cone shape of the injection pot portion 32. When the plunger 33 slides to the lower end, the tip portion is located above the supply passage 34. It is located. A nozzle 5 is provided at the lower end of the supply path 34 so as to be detachable.
[0023]
The mold 4 includes a movable lower mold 41, a fixed upper mold 42, and a runner stripper plate 43 mounted on the upper mold 42. Above the runner stripper plate 43, an upper clamping plate 8 for fixing the molding machine and the upper mold 42 and positioning the nozzle 5 and a later-described nozzle touch 11a of the upper mold 42 is arranged. The upper clamping plate 8 is covered with an upper heating plate 6 having a built-in heater 6a, and an upper die plate 71 is disposed above the upper heating plate 6 via a heat insulating plate 7a. The lower die 41 has a built-in heater 41a. Below the lower die 41, a lower die plate 72 is disposed via a heat insulating panel 7b. The upper die plate 71 and the lower die plate 72 are linked by a tie bar 73, and guide movement of the lower mold 41 when the mold is closed and the mold is opened.
[0024]
On the runner stripper plate 43, a sprue 11 and a runner 12 are formed. The sprue 11 is formed at a substantially central portion of the runner stripper plate 43 by a through hole penetrating from the upper surface of the nozzle touch surface to the lower surface of the runner split surface, and is formed by the upper end of the nozzle touch 11a (see FIGS. 2 and 3). It is connected to the nozzle 5. The inner surface of the sprue 11 is formed as a frusto-conical inner surface. The lower end of the sprue 11 communicates with the base end of the runner 12. The runner 12 is formed in a groove shape on the lower surface of the runner stripper plate 43, and the plurality of runners 12 extend almost radially from the lower end of the sprue 11. A gate 13 communicates with each end of the runner 12. Note that the lower surface of the runner stripper plate 43 is in close contact with the upper surface of the upper mold 42, and the runner 12 is formed in a passage shape with the groove-shaped bottom closed by the upper mold 42.
[0025]
The gate 13 is formed by a through hole communicating from the upper surface of the upper mold 42 to the upper cavity 14a formed on the lower surface of the upper mold 42. The lower mold 41 has a lower cavity 14b which forms the cavity 14 in cooperation with the upper cavity 14a. Therefore, the cavity 14 communicates with the injection pot portion 32 of the injection cylinder 3 via the gate 13, the runner 12, the sprue 11, and the supply path.
[0026]
With the lower mold 41, the upper mold 42, and the runner stripper plate 43 in close contact with each other, a guide hole 15 communicating with the sprue 11 is formed through the lower mold 41, the upper mold 42, and the heat insulating plate 7a. ing. A rod-shaped shunt 16 is loosely inserted into the guide hole 15 slidably guided by the guide hole 15. The tip of the shunt 16 is located in the sprue 11, and the tip has a conical outer surface that matches the frusto-conical shape of the sprue 11. Therefore, in the sprue 11, the flow path shape is formed in an annular shape.
[0027]
A driving means 50 for moving the shunt 16 is provided in the lower clamping plate 9. The driving means 50 can be provided on the lower die plate 72. As shown in FIGS. 2 and 3, the driving means 50 is constituted by a worm gear in which a worm wheel 51 and a worm 52 are combined. As shown in FIG. 2, the worm 52 is formed above the lower cranking plate 9 at the center of a drive rod 53 that is horizontally hung and rotatably supported. Rotational power is transmitted to a driving source 53 such as a motor (not shown). A female screw 51b is formed on the inner surface of the boss 51a of the worm wheel 51. A support rod 17 is connected to the lower end of the shunt 16, and the support rod 17 is loosely inserted into the guide hole 15. A male screw portion 17a screwed with the female screw 51b is formed in a portion of the lower portion of the support rod 17 protruding from the guide hole 15. Further, the support rod 17 is prevented from rotating.
[0028]
The operation of the injection molding machine according to the present invention configured as described above will be described below.
[0029]
When the drive source (not shown) operates, the drive rod 53 rotates, and the worm 52 rotates. The worm wheel 51 screwed to the worm 52 also rotates. A female screw 51b is formed on the boss 51a of the worm wheel 51, and the male screw 17a of the support rod 17, which is prevented from rotating, is screwed into the female screw 51b. The rod 17 moves up and down in the guide hole 15 according to the rotation direction of the worm wheel 51. Since the shunt 16 is connected to the upper end of the support rod 17, the shunt 16 moves up and down in the sprue 11.
[0030]
The sprue 11 is in a state where a flow path having an annular cross section is formed due to the splitter 16 being located inside. Since the length and area of the flow path are changed according to the position of the shunt 16 with respect to the sprue 11, the flow path resistance is changed.
[0031]
On the other hand, rubber, which is a molding material, is supplied from the supply port 23, is pushed toward the neck portion 24 by the rotation of the screw 22, passes through the check valve 25, and is injected through the communication passage 26. It is supplied to the pot section 32. When the molding material is supplied to the injection pot portion 32, the plunger 33 is pushed up, and when the plunger 33 is pushed up to a position corresponding to the injection amount, the rotation of the screw 22 stops and the molding material enters the injection pot portion 32. Supply stops. Next, the plunger 33 is pressed by a drive source (not shown). At this time, the molding material in the injection pot portion 32 tries to return to the extrusion device 2 through the communication passage 26, but does not flow backward because it is blocked by the check valve 25. Therefore, the molding material in the injection pot portion 32 is injected from the nozzle 5 to the sprue 11 through the supply path 34 by the lowering of the plunger 33. The molding material supplied to the sprue 11 is pushed to the runner 12 through a flow path around the shunt 16 located in the sprue 11, and is further injected into the cavity 14 through the gate 13. Will be. Next, the molded product that has been cured by heating, opened, and solidified in the cavity 14 is taken out.
[0032]
When it is necessary to change the injection filling pressure, for example, when the molding material is changed or when the molded product is changed, the drive rod 53 is rotated, and the shunt 16 Is raised or lowered to a predetermined position. Thereby, the flow path length in the sprue 11 is changed and the flow path resistance is changed, so that the injection filling pressure is changed. The sprue 11 is formed of a conical inner surface with a reduced diameter on the nozzle 5 side so that the flowability of the molding material is good. Therefore, the shunt 16 is also formed of a conical outer surface that matches the conical shape of the sprue 11. For this reason, when the position of the splitter 16 is changed, the flow path area of the sprue 11 is also changed and the flow path resistance is changed, so that the injection filling pressure is changed. Further, if the position of the shunt 16 that can obtain the required injection filling pressure is known in advance, the predetermined injection filling pressure can be easily set by locating the shunt 16 at the position. The position of the shunt 16 can be easily confirmed by providing a position sensor or the like for detecting the position of the support rod 17, for example. Further, it is also possible to determine the initial position of the drive means and determine the position of the shunt 16 according to the rotation angle from the initial position.
[0033]
Further, as shown in FIGS. 2, 3 and 5, a shunt 18 is also provided for the opening of the gate 13. That is, the guide hole 19 penetrating the runner stripper plate 43 is formed, and the shunt 18 is movably guided in the guide hole 19. The tip of the shunt 18 faces the opening of the gate 13 communicating with the runner 11, and the movement of the shunt 18 allows the opening area to be adjusted in relation to the opening. Further, the movement of the shunt 18 can be performed by transmitting the power of a driving source, as in the case of the shunt 16, and for example, an external thread is formed on the support rod 18a of the shunt 18 to guide the guide. A female screw screwed with the male screw may be formed in the hole 19, and the shunt 18 may be moved by rotating the support rod 18a according to the screwing relationship between the male screw and the female screw.
[0034]
By lowering the shunt 18 and bringing its tip closer to the opening of the gate 13, the area of the opening becomes smaller and the flow path resistance can be increased. In addition, when the shunt 18 is raised, the opening area increases, so that the flow path resistance can be reduced. Accordingly, the injection filling pressure can be adjusted by adjusting the position of the shunt 18.
[0035]
Further, in the case of moving using the power of the driving source like the shunt 16, by measuring the injection filling pressure, the position of the shunt 16 can be changed based on the detection data. it can. For example, pressure detection means 61 for measuring a pressure acting as a load when the plunger 33 is pressed down is provided, and detection data relating to the injection filling pressure measured by the pressure detection means 61 is sent to the drive control means 62. In the drive control means 62, an optimal injection filling pressure according to a molding material or a molded product is registered in advance as setting data, and the setting data is compared with the detection data, and the injection filling pressure is compared with the detected data. A drive signal relating to increase / decrease is output to the drive means 63. The drive means 63 rotates the drive rod 53 at an angle and direction required based on the drive signal. As a result, the shunt 16 moves to change the injection filling pressure. The drive control means 62 can be set with comparison data by an external operation. For example, when molding the same molded product with the same material, the vulcanization rate or the like may change due to a change in the material lot. In such a case, check the molded product and, for example, if scorch is generated, it is necessary to move the shunt 16 to increase or decrease the flow path resistance in the sprue 11. To change the injection filling pressure.
[0036]
【The invention's effect】
As described above, according to the injection molding die of the present invention, the flow resistance in the sprue can be changed by moving the splitter loosely inserted into the sprue, thereby reducing the injection filling pressure. Can be adjusted. Therefore, when the material or the mold is changed, the optimum injection filling pressure can be set without replacing the nozzle, and a good molded product can be obtained. In addition, since the shunt is moved by the power of the driving means, the operation for adjusting the injection filling pressure can be easily performed without the complexity of manual operation. For this reason, productivity by an injection molding machine can be improved.
[0037]
Further, according to the injection mold according to the second aspect of the present invention, the area of the gate opening can be adjusted by moving the shunt that faces the opening of the gate. For this reason, the flow path resistance at the gate opening can be increased or decreased, and the injection filling pressure can be adjusted.Therefore, when the material or the mold is changed, the optimum injection filling pressure can be obtained without replacing the nozzle. It can be set and a good molded product can be obtained.
[0038]
Further, according to the injection molding die of the third aspect of the present invention, since both the flow path resistance in the sprue and the flow path resistance in the gate can be easily adjusted, the injection filling pressure can be easily adjusted to an optimum value. Can be adjusted.
[0039]
Further, according to the injection mold of the fourth aspect, the injection filling pressure can be adjusted in real time. For this reason, even when the molded product or the mold is replaced, the quality of the molded product is changed due to the change of the material lot, and the injection filling pressure over time such as when the flow channel is worn or the material stays in the flow channel. Variations can be easily and promptly dealt with, without causing scorch or insufficient thermosetting reaction when using rubber or thermosetting resin, and using thermoplastic resin as material. In each case, the quality of the molded product can be stably maintained in a good condition by contributing to thermal decomposition of the material and stabilization of the solidified state by cooling.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic structure of a part of an injection mold and an injection molding machine according to the present invention.
FIG. 2 is a partially cut front view illustrating a schematic structure of an injection mold according to the present invention.
FIG. 3 is a partially cut-away side view of the mold shown in FIG. 2;
FIG. 4 is a sectional view showing a structure of a main part according to the present invention.
FIG. 5 is a sectional view showing a structure of a main part according to the present invention.
FIG. 6 is a block diagram illustrating control means for controlling operations of an injection mold and an injection molding machine according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Casing 2 Extruder 3 Injection cylinder
31 Cylinder section
32 Injection pot
34 Supply path 4 Mold
41 Lower mold
42 Upper type
43 Spruce stripper plate 5 Nozzle 8 Upper clamping plate 9 Lower crank pink plate
11 sprue
11a Nozzle touch
12 runner
13 gate
14 cavities
15 Guide hole
16 splitter (for sprue)
17 Support rod
17a Male thread
18 Shunts (for gate)
19 Guide hole
50 Drive means
51 Worm wheel
52 warm
53 Drive rod
61 Pressure detection means
62 Drive control means
63 Drive means
71 Upper die plate
72 Lower die plate
73 Tie bar

Claims (4)

Concentrically insert the shunt into the sprue formed between the fixed runner and both sides of the nozzle touch,
Supporting the splitter movably in the axial direction of the sprue,
A mold for injection molding, comprising a driving means for moving the shunt. In an injection mold having a three-plate mold structure having a runner split surface and a cavity split surface separately,
Forming a through-hole through the runner stripper plate in the runner stripper plate, coaxially with the gate formed between both surfaces of the runner and the cavity;
A mold for injection molding, wherein a shunt is supported in the through hole so as to be movable in the axial direction of the through hole. In an injection mold having a three-plate mold structure having a runner split surface and a cavity split surface separately,
The sprue splitter is inserted concentrically into the sprue formed between the runner of the runner stripper plate and both sides of the nozzle touch,
The sprue splitter is supported so as to be movable in the axial direction of the sprue,
Having a driving means for moving the sprue shunt,
Forming a through-hole through the runner stripper plate in the runner stripper plate, coaxially with the gate formed between both surfaces of the runner and the cavity;
A shunt for a gate is supported in the through hole so as to be movable in an axial direction of the through hole. Pressure detection means for measuring the injection filling pressure during injection molding,
Drive control means for sending a drive signal to the drive means,
The drive control means has setting data about an injection filling pressure corresponding to a molded product, can input comparison data by an external operation, compares the setting data or the comparison data with the detection data, A drive signal for moving the shunt to a position corresponding to the injection filling pressure of
The injection mold according to any one of claims 1 to 3, wherein the driving means operates in accordance with the driving signal to change a moving position of the shunt.

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