JP2007083463A - Mold assembly for sucking cavity under vacuum and a molding machine including it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold assembly for sucking the gas in a cavity under vacuum without moving an ejector pin immediately before ejection. <P>SOLUTION: The mold assembly 1 is constituted so that the ejector pin 42 is fixed to an ejector plate 41 while a center pin 46 is attached to the ejector plate so as to be retracted by a predetermined distance and on the center pin retreats when an ejector rod 50 is retracted. Further, the mold assembly 1 is constituted so that the air passing channel 61 communicating with a vacuum suction device 70 is provided to a part along the center pin to communicate with the cavity 30 only when the center pin is retracted. The cavity is sucked under vacuum when the ejector rod is retracted just before injection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a mold apparatus for molding a molded product by filling a cavity with a molten resin from a sprue bush, and ejecting the sprue and the molded product with a center pin and an ejector pin. The present invention relates to a molding apparatus including a mold apparatus for vacuum suction.

  The technique of sucking and removing gases such as air and nitrogen gas in the cavity immediately before filling with the molten resin is particularly important for improving the moldability of a thin and fine precision molded product. This is because in this type of molding, the molten resin is filled at a high speed and a high pressure, so that air or the like must be sufficiently removed in advance. For this reason, various methods and apparatuses have been proposed, but all have advantages and disadvantages. In particular, a method and an apparatus for vacuum suction from a cavity after a mold is completely closed have been proposed. According to this type of technology, the cavity can be directly vacuumed after the mold is closed, so that the gas in the cavity can be quickly and strongly sucked.

  In this type of technology, the cavity of the mold device is naturally connected to the vacuum suction device via some opening / closing device. However, the opening / closing device should be as simple as possible and should not complicate the control on the molding device side as much as possible. As the most prototype of such a mold apparatus, a molding mold shown in FIG. 6 has been proposed (for example, Patent Document 1). This mold has an air passage 97 having one end opened in the cavity 96 and the other end communicating with the vacuum source 106, and a blocking body 98 provided between the cavity 96 and the communication passage 97. The blocking body 98 constitutes one surface of the cavity 96 at its tip, and moves to open and close communication between the cavity 96 and the air passage 97 to switch between start and stop of vacuum suction of the cavity 96. Although this blocking body 98 is not particularly specified as an ejector, it is described that it may have an ejector function.

  In this molding die, when the blocking body 98 is an ejector pin, the blocking body driving unit 102 corresponds to a conventionally known ejector driving device. A member (assumed to be 100) that is located between the tip of the rod equivalent and the base end of the blocking body 98 and is pressed by a spring corresponds to an ejector plate. Therefore, it is assumed that the blocking body 98 moves together with the ejector plate 100 and moves backward by a predetermined distance to the vacuum suction position in addition to the conventionally known molding position and protrusion position. On the other hand, when the blocking body 98 corresponds to a sprue lock pin or a center pin, the blocking body driving unit 102 similarly corresponds to an ejector rod drive device. Accordingly, the sprue lock pin and the like are configured in the same manner as described above and move together with the ejector plate 100. Accordingly, when the molding die includes two types of members such as an ejector pin and a sprue lock pin, it is assumed that both of these members are fixed to the ejector plate 100 and moved simultaneously.

  According to the molding die of the above patent document, the cavity can be vacuum sucked in a short time from the mold closing to the start of injection, so that the cavity gas can be sucked quickly and strongly without delaying the molding cycle. it can. In addition, since the start and stop of the suction of the cavity are switched between the backward operation and the forward operation of the blocking body 98, the control of the blocking body driving unit 102 only needs to add the above-described backward control to the conventional control. .

JP 53-31767 (Fig. 2)

  However, in the molding die of the above-mentioned patent document, when the blocking body 98 is two types of members, ie, an ejector pin and a sprue lock pin (center pin), these members have to move together as described above. Inferred. Then, it is presumed that the ejecting operation of the ejector pin is always included in the vacuum suction operation of the cavity, and the injection cannot be performed until the ejector pin is surely returned to the molding position. Therefore, this molding die is not particularly suitable for increasing the speed of precision molding of thin and fine molded products. In this type of molding, molten resin is filled at high speed and high pressure and the time required for each process is shortened to the utmost limit. Therefore, the molding position of the ejector pin is in a state of being accurately maintained during molding, This is because it is required to be able to shift to injection immediately after suction.

  Accordingly, the present invention provides a mold apparatus having an ejector pin and other center pins, etc., that vacuum-sucks the gas in the cavity only by moving the center pin and the like while the ejector pin is fixed at a predetermined molding position. The purpose is to propose. Another object of the present invention is to propose a molding apparatus for mounting and molding the above mold apparatus.

In order to solve the above-described problems, a molding apparatus according to the present invention includes a mold apparatus that ejects a molded product and a spur formed by a cavity and a sprue bush through an ejector plate and an ejector pin and a center pin. In the molding equipment,
(1) The mold apparatus includes the center pin attached to the ejector plate so as to be retractable by a predetermined distance, and a vent path communicating with a vacuum suction device is provided in a part of the mold apparatus along the center pin. A center pin through-hole that communicates the air passage to the cavity side only when the center pin is retracted by a predetermined distance at an end of the air passage,
(2) Immediately before injection, the ejector rod is retracted and only the center pin is retracted by a predetermined distance, so that the center pin opens the center pin through hole and vacuums the cavity,
(3) When the vacuum suction is not performed, the ejector pin and the center pin operate integrally with the ejector plate.

  Further, the molding apparatus of the present invention retracts the ejector rod immediately after closing the mold, retracts only the center pin by the predetermined distance, starts vacuum suction of the cavity, and obtains a predetermined degree of vacuum. Immediately after that, the ejector rod is returned, the center pin is returned to the molding position, the suction of the cavity is stopped, and immediately after that, the injection is started.

Further, the mold apparatus of the present invention is a mold apparatus in which an ejector rod of the ejector driving device advances an ejector pin and a center pin, which are formed by a cavity and a sprue bush, through an ejector plate. ,
(1) The center pin forms the bottom surface of the sprue lock hole formed in the movable mold at the tip, while the base end penetrates the ejector plate and comes into contact with the ejector rod. It is accommodated movably in the guide hole of the ejector plate at the collar,
(2) The center pin is pressed in the backward direction of the center pin by the compression coil spring through the flange portion,
(3) A gap is formed between the back of the flange of the center pin and the bottom of the guide hole so that the center pin can be further retracted from the molding position by a predetermined distance from the molding position.
(4) A vent path communicating with the vacuum suction device is formed in a portion along the outer periphery of the center pin and excluding a portion adjacent to the ejector chamber side and a portion adjacent to the sprue lock hole side,
(5) By forming the thickness dimension of the portion where the through hole of the center pin is adjacent to the end on the sprue lock hole side of the ventilation path smaller than the gap,
(6) When the ejector rod is retracted, only the center pin is retracted by the predetermined distance, and the cavity is communicated with the air passage from the sprue lock hole to vacuum the cavity.

  In the mold apparatus of the present invention, the vent path may communicate with an ejector chamber, and the ejector chamber may be hermetically sealed and communicated with a vacuum suction device.

  According to the molding apparatus of the present invention, since vacuum suction is performed by the retreating operation of the center pin only immediately before injection, unnecessary vacuum suction is avoided during other processes, and a short time before injection after mold closing. The cavity is strongly sucked by vacuum. In addition, in a mold apparatus including an ejector pin and a center pin, vacuum suction of the cavity is performed only by retraction of the center pin, so that the position of the ejector pin immediately before injection is performed while being held at the molding position. In addition, at this time, since the ejector pin is fixed to the ejector plate in the conventional manner, the molding position of the ejector pin is accurately positioned by the ejector plate. Therefore, in the molding apparatus of the present invention, injection can be started immediately after vacuum suction.

  Further, according to the above molding apparatus, in addition to the control of the conventional molding position and the protruding position of the ejector rod, it is possible to obtain the predetermined distance of the ejector rod after the mold is closed and the predetermined vacuum degree of the cavity. Since it is only necessary to add the return control of the ejector rod immediately after that, there is almost no change in control, and the control itself is not complicated.

  Further, according to the mold apparatus of the present invention, the center pin is attached to the ejector plate by the ejector rod and the compression coil spring so as to be movable by a predetermined distance, and the center pin through-hole is sprung by the movement of the center pin by a predetermined distance. Open in the lock hole. Therefore, it is possible to easily open and close the communication between the cavity and the vacuum suction device by adding only the retracting operation of the ejector rod to retract only the center pin.

  Further, according to the above molding apparatus, since the vent passage is communicated with the vacuum suction device using the ejector chamber, the communication hole that communicates the vent passage with the vacuum suction device when the mold is complicated is provided with a metal mold. It is not necessary to form in the mold member. Moreover, the temperature control piping can be easily routed.

  As shown in the cross section of FIG. 1, the mold apparatus 1 of the present invention includes at least a fixed mold 10 and a movable mold 20 and a cavity 30 formed between them. This configuration is the most basic of the mold apparatus. First, the same thing as the conventionally well-known structure of a metal mold apparatus is demonstrated previously. 1 shows a state immediately after completion of mold closing, and a right half of FIG. 1 shows a state where vacuum suction is performed.

  The fixed-side mold 10 includes a fixed-side mold plate 11, a fixed-side mounting plate 12, a sprue bush 13, and a locating ring 14. The movable side mold 20 includes a receiving plate 21, a core 22, a movable side mold plate 23, a movable side mounting plate 24, and a spacer block 25. The cavity 30 in which the molded product 31 is molded communicates with the sprue hole of the sprue bush 13 by the runner 32. The movable side mold plate 23 facing the sprue bush 13 is formed with a conventionally known sprue lock hole 34 having, for example, a reverse taper shape in which the tip of the sprue 33 solidified by the sprue bush 13 is locked.

  The ejector device 40 includes an ejector plate 41, an ejector pin 42 fixed to the ejector plate 41, and a return pin 43. The ejector plate 41 moves while being guided by the return pin 43 in a space defined by the receiving plate 21, the movable side mounting plate 24, and the spacer block 25, that is, the ejector chamber 44. Between the receiving plate 21 and the ejector plate 41, a compression coil spring 45 that urges the ejector plate 41 in the backward direction (downward direction in the figure) is mounted along the return pin 43, and the ejector plate 41 is moved backward. This is performed by the biasing force of the compression coil spring 45. Therefore, the retracted position of the ejector plate 41 is a position where it abuts against the stop pin 26. This position is a molding position described later. Reference numeral 50 denotes an ejector rod that is driven by an ejector driving device built in a movable platen (not shown).

  According to this conventionally known configuration, the ejector pin 42 is accurately positioned at the molding position by the ejector plate 41 as in the prior art, and its tip constitutes a part of the surface of the core 22 at the time of molding.

  Next, a configuration unique to the present invention will be described. The mold apparatus 1 further includes a center pin 46. The pin 46 faces the sprue lock hole 34 at the tip, and contacts the ejector rod 50 through the ejector plate 41 at the base end. And the collar part 46a formed in the base end vicinity is accommodated in the guide hole 41a formed in the ejector plate 41 so that a movement is possible. A compression coil spring 47 presses the flange 46a of the center pin 46 in the backward direction.

  Further, the mold apparatus 1 has a center pin 46 as shown in FIG. 3 at a portion along the outer periphery of the center pin 46 except for a portion adjacent to the ejector chamber 44 side and a portion adjacent to the cavity 30 side. The air passage 61 is formed in a hole having an inner diameter larger than the outer diameter. 3 is a cross-sectional view taken along the line AA in FIG. More specifically, the ventilation path 61 is formed at an intermediate portion excluding the vicinity of the outer surface of the receiving plate 21 and the vicinity of the outer surface of the movable mold plate 23. And in those adjacent parts, the center pin 46 moves in the through hole, that is, the center pin through hole 23a. Of course, the gap between the through holes is formed to the minimum as long as the operation of the center pin 46 is not hindered, and the airtightness is ensured to the maximum. The mold apparatus 1 also includes a communication hole 62 that guides the ventilation path 61 to the outer surface of the mold apparatus. More specifically, the communication hole 62 is formed in the mold member of the receiving plate 21 or the movable side plate 23 and opens to the outer surface thereof. A vacuum source 71 for sucking gas is connected to the communication hole 62 by a pipe 72.

  Further, in the mold apparatus 1 of the present invention, an ejector is provided so that the center pin 46 in the molding position as shown in the left half of FIG. 1 can be further retracted to the retracted position as shown in the right half of FIG. A gap G is formed between the bottom of the guide hole 41a of the plate 41 and the lower surface of the flange 46a of the center pin 46 (the surface facing the bottom of the guide hole 41a). This gap G is formed when the tip of the return pin 43 is in the molding position where the tip of the return pin 43 is in contact with the stationary mold 11, the ejector plate 41 is in contact with the stop pin 26, and the ejector plate 41 is in contact with the ejector rod 50. Therefore, when the ejector rod 50 moves backward by at least the gap G from the molding position, the ejector rod 50 moves backward by the distance G from the molding position of the center pin 46. When the ejector rod 50 reverses and returns to the molding position, the center pin 46 returns to the original molding position. On the other hand, as shown in FIG. 2, the thickness dimension L of the part adjacent to the end of the air passage 61 on the sprue lock hole 34 side, that is, the length dimension L of the center pin through-hole 23a at that part can be set back. It is formed smaller than the gap distance G. Therefore, when the ejector rod 50 moves backward through the gap G and the center pin 46 moves backward through the gap G, the sprue lock hole 34 opens into the air passage 61.

  70 is a vacuum suction device. A conventionally known vacuum source 71 such as a vacuum pump is connected to the communication hole 62 by a suction pipe 72 and sucks gas. The vacuum suction device 70 includes a pressure sensor 74 that detects a negative pressure and an on-off valve 73 that operates when an abnormality occurs. As will be described later, the control device 80 of the molding machine not shown in the drawing utilizes the mold apparatus 1 by adding at least the control of the ejector rod 50 to the molding control of the molding device not shown in the drawing. At this time, the pressure in the pipe 72 detected by the pressure sensor 74, that is, the pressure in the cavity 30 is also fed back to the control device 80.

  Although not shown in the mold apparatus 1 of the present invention, the vent passage 61 can be communicated with the vacuum suction device 70 using the ejector chamber 44. In this case, the ejector chamber is hermetically sealed with a side plate or the like, the ventilation path 61 opens to the ejector chamber 44 side, and the vacuum suction device 70 communicates with the ejector chamber 44 side. By doing so, when the mold is complicated, it is not necessary to form the communication hole 62 in the mold member through a complicated path. Further, since there is no interference between the temperature control pipe and the communication hole, the temperature control pipe can be easily routed.

  In the mold apparatus 1 of the present invention, an example in which the tip of the center pin 46 is straight is shown, but a conventionally known hook-shaped sprue lock pin may be used. In this case, the sprue lock hole 34 is not straight but tapered. Even in this case, the communication between the air passage 61 and the sprue lock hole 34 is closed when the center pin 46 is in the molding position, and the communication is opened when the center pin 46 is in the retracted position. Of course, the sprue lock hole 34 may be formed with an annular groove.

  The mold apparatus 1 described above is mounted on a mold clamping apparatus including a fixed platen and a movable platen (not shown) via a fixed side mounting plate 12 and a movable side mounting plate 24. A nozzle of an injection device (not shown) is brought into contact with the sprue bush 13, and the control device 80 of the molding machine controls the injection device and also controls the mold clamping device. Control is performed as shown in FIG. Molding processes such as mold closing, vacuum suction, injection, and extrusion of molded products are shown in FIGS. 1 and 4 (a), (b), and (c). The position of the center pin and the state of the pressure in the cavity corresponding to the molding process of one cycle are shown in FIG. In addition, the length (interval) of the horizontal axis which shows a process does not extend so much in an actual shaping | molding operation.

  In the following molding operation, the vacuum source 71 is in a continuous operation state as long as one series of molding is performed. The on-off valve 73 does not open or close the suction pipe 72 unless there is an abnormality. This is because the cavity 30 and the air passage 61 communicate only when the center pin 46 moves backward.

  First, the mold is closed as usual, and the left half of FIG. 1 is obtained. After that, the injection process is started as usual, but immediately before that, as shown in the right half of FIG. 1 or FIG. Retreat. The ejector pin 42 is accurately held in the molding position as it is. When the center pin 46 is retracted in this manner, the air passage 61 communicates with the sprue lock hole 34 via the center pin through hole 23a, the cavity 30 communicates with the communication hole 62, and the gas in the cavity 30 is vacuumed. The intracavity pressure rapidly decreases as shown in FIG. 5 because the sucked volume is small. When the pressure in the cavity reaches a predetermined predetermined degree of vacuum, the ejector rod 50 returns to the molding position and the center pin 46 immediately returns to the molding position as shown in FIG. And the injection is started immediately. At this time, the pressure in the cavity 30 is maintained in a vacuum state as it is, so that no filling failure occurs in this injection.

  When injection is started, molten resin is filled into the cavity 30 from the sprue bush 13. The pressure in the cavity 30 increases according to the filling pressure of the resin, and gradually decreases during the subsequent pressure holding process. When the cooling process of the molded product 31 is completed, the movable mold 20 is then opened to complete the mold opening. Then, as shown in (c), the ejector rod 50 moves forward by a predetermined stroke, and the ejector pin 42 and the center pin 46 project the molded product 31 and the sprue 33. Then, they are taken out and the mold is closed as shown in FIG. Thereafter, the molding process is repeated in the same manner as described above.

  According to the above-described mold apparatus 1 of the present invention, in the mold apparatus including the ejector pin 42 and the center pin 46, vacuum suction of the cavity 30 immediately before injection is performed in a state where the ejector pin 42 is held at the molding position. . Moreover, the molding position of the ejector pin 42 is accurately held by the ejector plate 41 during and after vacuum suction. Therefore, in the mold apparatus of the present invention, the injection can be started immediately after the vacuum suction is performed in a short period of time from the mold closing to the injection.

  Further, a molding apparatus equipped with the mold apparatus of the present invention can easily correspond to the present mold apparatus only by adding the following control. Regarding the control of the ejector rod 50, in addition to the control of the normal molding position and the protruding position, the control of the retreat position of the gap G is added immediately before the injection process. The return operation of the ejector rod is started in response to a feedback signal for reaching a predetermined degree of vacuum from the pressure sensor 74. However, the opening / closing control of the opening / closing valve 73 does not require addition of the opening / closing control.

  Of course, since vacuum suction is performed after the mold is closed, it is the same as before that the cavity 30 can obtain a sufficient degree of vacuum in a short time from the mold closing to the start of injection. In addition, since the vacuum suction is performed only by the operation in which the center pin 46 is retracted for a short time immediately before the injection, it is avoided that the vacuum source 71 sucks the vacuum during the subsequent injection, pressure holding, cooling, and ejection processes. The Further, by eliminating the useless operation, the gas can be strongly sucked from the start of the suction, so that the suction efficiency of the vacuum suction device 70 is improved. Further, since the on-off valve 73 may be left open during the molding operation, the on-off control is not required.

It is sectional drawing of the metal mold | die apparatus of this invention, the figure of the left half is in the state immediately after completion | finish of mold closing, and the figure of the right half is in the state which is vacuum-sucking. It is sectional drawing which shows the form of the center pin and ventilation path of this invention. It is AA arrow sectional drawing of FIG. It is a state figure of the metal mold | die in the middle of a shaping | molding process of the metal mold | die apparatus of this invention. It is a change figure of the center pin position in the middle of a molding process, and the pressure in a cavity of the metallic mold apparatus of the present invention. It is sectional drawing of the conventional molding die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold apparatus 10 Fixed side mold 13 Sprue bush 20 Movable side mold 23a Center pin through hole 30 Cavity 31 Molded product 33 Sprue 34 Sprue lock hole 41 Ejector plate 41a Guide hole 42 Ejector pin 44 Ejector chamber 46 Center pin 46a Hook 47 Compression coil spring 50 Ejector rod 61 Ventilation path 62 Communication hole 70 Vacuum suction device G Gap L Thickness dimension of the part adjacent to the sprue lock hole side of the ventilation path (length dimension of the center pin through hole)

Claims (4)

In a molding apparatus including a mold apparatus that ejects a molded product and a spru formed by a cavity and a sprue bush through an ejector plate by an ejector pin and a center pin.
(1) The mold apparatus includes the center pin attached to the ejector plate so as to be retractable by a predetermined distance, and a vent path communicating with a vacuum suction device is provided in a part of the mold apparatus along the center pin. A center pin through-hole that communicates the air passage to the cavity side only when the center pin is retracted by a predetermined distance at an end of the air passage,
(2) Immediately before injection, the ejector rod is retracted and only the center pin is retracted by a predetermined distance, so that the center pin opens the center pin through hole and vacuums the cavity,
(3) The molding apparatus characterized in that the ejector pin and the center pin operate integrally with the ejector plate when the vacuum suction is not performed.   Immediately after closing the mold, the ejector rod is retracted, only the center pin is retracted by the predetermined distance to start vacuum suction of the cavity, and when the predetermined degree of vacuum is obtained, the ejector rod is immediately returned, The molding apparatus according to claim 1, wherein the suction of the cavity is stopped by returning the center pin to the molding position, and immediately after that, injection is started. In a mold apparatus in which a molded product and a sprue formed by a cavity and a sprue bush are ejected by an ejector pin and a center pin, which are ejected by an ejector rod of an ejector drive device through an ejector plate.
(1) The center pin forms the bottom surface of the sprue lock hole formed in the movable mold at the tip, while the base end penetrates the ejector plate and comes into contact with the ejector rod. It is accommodated in the guide hole of the ejector plate at the collar so as to be retractable,
(2) The center pin is pressed in the backward direction of the center pin by the compression coil spring through the flange portion,
(3) A gap is formed between the back of the flange of the center pin and the bottom of the guide hole so that the center pin can be further retracted from the molding position by a predetermined distance from the molding position.
(4) A vent path communicating with the vacuum suction device is formed in a portion along the outer periphery of the center pin and excluding a portion adjacent to the ejector chamber side and a portion adjacent to the sprue lock hole side,
(5) By forming the thickness dimension of the portion where the through hole of the center pin is adjacent to the end on the sprue lock hole side of the ventilation path smaller than the gap,
(6) When the ejector rod is retracted, only the center pin is retracted by the predetermined distance, the cavity is communicated with the air passage from the sprue lock hole, and the cavity is vacuum sucked. apparatus.   4. The mold apparatus according to claim 3, wherein the vent passage communicates with the ejector chamber, and the ejector chamber is hermetically sealed and communicates with a vacuum suction device.

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