JP2007083567A - Mold assembly including vacuum suction valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold assembly having a vacuum suction valve being a valve for controlling the vacuum suction operation of a runner groove and unified compactly. <P>SOLUTION: The mold assembly 40 has a vacuum suction valve 20 mounted thereon in a posture along its parting surface PL. The valve 20 includes the needle pin 23 moving through the hollow cylinder part 21 by the air cylinder 22 fixed to the base end of the hollow cylinder part 21 and the leading end part 23a of the needle pin 23 is constituted so as to open and close the air passing channel 25 of the cylindrical part 21 connected to a vacuum generator through an opening and closing port 21b to perform the vacuum suction of a cavity from a runner groove 47. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold apparatus including a vacuum suction valve which can be mounted on a mold apparatus and which switches between start and stop of a vacuum suction operation of a cavity.

  The technique of sucking and removing gas such as air and nitrogen gas in the cavity and runner groove 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, and among them, a method and apparatus for vacuum suction of the cavity after the mold is completely closed has 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 mold apparatus is naturally connected to a vacuum suction device, and therefore includes a switching valve that opens and closes communication between the vacuum suction device and the cavity. With regard to the switching valve, a molding apparatus shown in FIG. 5 (for example, Patent Document 1) or a mold gas venting apparatus (for example, Patent Document 2) in which the molding apparatus is improved has been proposed.

  The former molding die incorporates a pin 4 that advances and retreats by an air cylinder 3 in an air vent hole 5 that communicates with the cavity 1, and has a branch hole that branches from the air vent hole 5. Communicating with Then, the molding die performs vacuum suction of the cavity 1 by opening and closing the air vent hole 5 by the forward and backward movement of the pin. Such a valve mechanism includes a problem that the pin 4 facing the cavity 1 moves backward without resisting the high injection pressure of the molten resin and leaves a trace on the surface shape of the molded product.

  The latter degassing device for the mold is not shown in the drawing, but prevents the former problem, that is, the valve body corresponding to the pin from retreating from the valve seat due to its injection pressure. The prevention technique is to prevent the valve body from retreating by a toggle mechanism or a self-locking mechanism.

  According to the technique common to both, the cavity can be vacuum-sucked in a short period of time from normal mold closing to injection. Moreover, it can be sucked until just before injection. The start and stop of vacuum suction of the cavity can be easily switched with an air cylinder.

JP 56-82231 A (Fig. 2) JP-A-3-297548 (FIG. 1)

  However, in the valve mechanism or the degassing device for a mold described in the above-mentioned patent document, the air vent hole or the opening / closing port of the valve opens directly into the cavity. In the state where a high injection pressure is applied to the position of the valve existing in the cavity, there is still a possibility that the surface of the molded product will be adversely affected. Further, since the hole communicating with the vacuum generator is separately formed in the mold member, it becomes an obstacle in routing the temperature control pipe. In addition, since the valve mechanism or the degassing device for the mold is not compactly unitized, the movable side mold plate or the fixed side mold, which is a standard component whose thickness of the mold is not particularly thick. It cannot be easily attached to the board.

  Therefore, the present invention can switch the vacuum suction operation of the cavity as described above, as well as a vacuum suction valve that is compactly unitized and can be easily attached to a standard component of the mold, The object is to propose a mold apparatus equipped with it.

In order to solve the above problems, the mold apparatus of the present invention moves in the axial direction in the hollow cylindrical portion by the hollow cylindrical portion and an air cylinder fixed to the proximal end side of the hollow cylindrical portion. Including needle pins,
The hollow cylindrical portion has an air passage for allowing air to pass between the inner periphery thereof and the outer periphery of the needle pin, an exhaust port connected to a vacuum suction device for vacuum-sucking air on the proximal end side thereof, and an end thereof An opening that opens on the side of the air passage to the distal end surface of the hollow cylindrical portion,
The inner hole of the opening / closing port and the tip of the needle pin are formed on a taper surface that is substantially the same tapered toward the tip.
A mold apparatus including a vacuum suction valve that performs an opening / closing operation of the opening / closing port by an operation of abutting and separating the tip of the needle pin from the opening / closing port,
The vacuum suction valve is mounted in a posture along the parting surface of the mold apparatus,
By allowing the front end surface of the hollow cylindrical portion to be in close contact with the bottom of the insertion hole of the hollow cylindrical portion and allowing the opening / closing port to communicate with the runner groove of the mold device,
The runner groove can be vacuumed by the vacuum suction valve.

  According to the mold apparatus of the present invention, the mold apparatus includes at least a hollow cylindrical portion, a needle pin, and an air cylinder. In the hollow cylinder, an air passage connected to the vacuum suction device and the runner groove are provided. A vacuum suction valve including an opening / closing port that opens and closes is mounted in a posture along the parting surface. Therefore, the vacuum suction valve is compactly unitized and can be easily mounted on a mold member having a standard configuration, and its maintainability is improved.

  As shown in the cross section of FIG. 1, the vacuum suction valve 20 of the present invention includes at least a hollow cylindrical portion 21, an air cylinder 22, and a needle pin 23. The hollow cylindrical portion 21 has a cylindrical outer surface 21a that is sufficiently smoothed so that it is easy to attach most of the hollow cylindrical portion 21 to the mold apparatus 40, and is precisely finished to a tolerance dimension that takes into account the fit. Practically, the outer diameter of the hollow cylindrical portion 21 is elongated to about 10 mm. The air cylinder 22 is integrally fixed to the proximal end side of the hollow cylindrical portion 21, and includes therein a piston 24 incorporated therein so as to be movable back and forth by a conventionally known pneumatic device (not shown). The needle pin 23 is connected to the piston 24 at its proximal end and is attached in the hollow cylindrical portion 21 so as to be movable in the axial direction of the hollow cylindrical portion 21.

  The hollow cylindrical portion 21 has an air passage 25 that allows air to pass between the inner periphery thereof and the outer periphery of the needle pin 23, and includes an exhaust port 22a that discharges the air on the base end side. The hollow cylindrical portion 21 includes an opening / closing port 21b that opens the ventilation path 25 to the outside at the tip. As shown in FIG. 2 in an enlarged manner, the opening / closing port 21b has an inner hole formed in a tapered surface 21c tapered toward the tip side. In FIG. 2, the upper half of the needle pin shows the closed state of the opening / closing port, and the lower half of the drawing shows the opened state of the opening / closing port.

  The distal end portion 23a of the needle pin 23 is formed in a truncated cone having the same shape as the tapered surface so as to be in close contact with the tapered surface 21c of the opening / closing port 21b. And the head part 23b of the front-end | tip part 23a is formed so that the front-end | tip surface 21d of the hollow cylindrical part 21 may comprise the same surface, when it is moving forward. Usually, these surfaces, 23b and 21d, are formed in a plane perpendicular to the axial direction.

  The head 23b of the head cone tip 23a of the needle pin 23 incorporated in the hollow cylindrical portion 21 having an outer diameter of 10 mm may have an outer diameter of about 1.2 mm. If the head 23b is about 1.2 mm and the outer diameter of the piston 24 that receives the air pressure of 0.5 Mpa is about 25 mm, the needle pin 23 is prevented from retreating by an injection pressure of about 200 MPa. Because it can.

  The exhaust port 22a is connected to a vacuum suction device 30 including a vacuum generation source 31 such as a vacuum pump. In the vacuum suction device 30, a pressure sensor 33 (or a pressure switch 33) that detects the connection pipe 32 and the negative pressure of the pipe as the pressure of the cavity 45 on the mold side between the exhaust port 22 a and the vacuum generation source 31. ) Is provided. As will be described later, the vacuum generation source 31 of the present invention is in a continuous operation state during a series of molding operations, and it is not necessary to open and close the piping 32 with a valve or the like.

  In practice, the hollow cylindrical portion 21 and the air cylinder 22 are connected in series in the front-rear direction through a block member (not shown). The needle pin 23 is connected to a piston rod of a piston 24 (not shown) via a coupling (not shown). And it is comprised so that the coupling may be incorporated in the space formed in the block member.

  Further, bolts that can be screwed into the mold apparatus described below are inserted into the block members at the four corners. This is because when the vacuum suction valve 20 is inserted into the mold, the hollow cylindrical portion 21 can be strongly pushed into the insertion hole.

  The vacuum suction valve 20 configured as described above is compactly unitized. The mold apparatus 40 to which such a valve 20 can be mounted is a two-plate mold 41 having the most basic configuration as shown in FIG. 3 or a three-plate mold 42 as shown in FIG.

  The former mold 41 includes a conventionally known fixed-side mold 43, a movable-side mold 44, and a cavity 45 formed therebetween. In the mold, a runner groove 47 and an insertion hole 46 a for the vacuum suction valve 20 are formed in the movable side mold plate 46. The bottom part 46b of the insertion hole 46a is formed in the surface of the mutually same shape so that it may contact | adhere to the front end surface 21d of the hollow cylindrical part 21. FIG. The bottom 46 b is formed in contact with the runner groove 47 so that the opening / closing port 21 b faces the runner groove 47. Therefore, when the vacuum suction valve 20 is mounted in the insertion hole 46 a, the tip surface 21 d forms a part of the molding surface of the runner groove 47, and the opening / closing port 21 b opens directly into the runner groove 47.

  Naturally, the inner diameter of the insertion hole 46a is processed into a fitting dimension that matches the outer dimension of the vacuum suction valve 20, and is arranged in a posture along the parting surface PL. The vacuum suction valve 20 is preferably arranged as close to the parting surface PL as possible. For example, when the outer diameter of the hollow cylindrical portion 21 of the valve 20 is 10 mm, the entire cylindrical portion 21 is disposed within a depth range of 12 mm to 13 mm from the parting surface. Therefore, the vacuum suction valve 20 is well accommodated in the standard movable side plate 46 thickness dimension, which is not particularly thick. In addition, although illustration is abbreviate | omitted, a metal mold | die may have a stripper plate which protrudes a molded article or a runner in a surface. In this case as well, the insertion hole is formed in a stripper plate whose thickness is not particularly thick. Therefore, the vacuum suction valve is well accommodated in the stripper plate which is a movable mold member.

  The latter mold 42 is a mold apparatus including a conventionally known fixed-side mold 43, a movable-side mold 44, and a fixed-side mold plate 48 that opens with a delay when the mold is opened therebetween. In that mold, a runner and a sprue are formed between the fixed mold 43 and the fixed mold 48, and a cavity 45 is formed between the movable mold 44 and the fixed mold 48, Different from the former mold device. In the mold 42, a runner groove 47 and an insertion hole 48 a for the vacuum suction valve 20 are formed in the fixed-side mold plate 48.

  In other respects, the mold 42 is the same as the former mold 41, and the tip surface 21 d of the vacuum suction valve 20 forms one surface of the molding surface of the runner groove 47. Therefore, even in this mold 42, the vacuum suction valve 20 is well accommodated in the fixed-side mold plate 48 that is not so thick. Reference numeral 49 denotes a hole in which a sprue is formed.

  The vacuum suction valve 20 configured as described above closes the opening / closing port 21b when the tip 23a of the needle pin 23 is brought into contact with the inner hole 21c of the opening / closing port 21b, and the tip 23a is closed to the inner hole. When separated from 21c, the opening is opened. Since the taper surfaces with which both abut are formed in the same shape, the sealing performance between them is improved. A sufficient air gap can be secured only by retreating a short distance.

  The mold apparatus 40 including such a vacuum suction valve 20 is molded as follows. The mold apparatus described here may be a two-plate mold 41 or a three-plate mold 42. This is because it is distinguished only in the protrusion after the mold opening. In the following molding operation, the vacuum generating source 31 is in a continuous operation state during a series of molding operations.

  First, the mold is closed in the state shown in FIG. 3 or FIG. Then, immediately after that, the needle pin 23 moves backward and advances in a short time when injection is started, and vacuum suction is started and stopped. That is, immediately after the mold is closed, the needle pin 23 moves backward to open the opening / closing port 21b of the vacuum suction valve 20, the runner groove 47 communicates with the vacuum suction device 30, and the cavity 45 is vacuumed. Then, the pressure of the cavity 45 is detected by the pressure sensor 33. As soon as the pressure reaches a predetermined negative pressure, the needle pin 23 moves forward, closes the opening / closing port 21b and stops vacuum suction of the cavity. Immediately thereafter, injection is performed as in the prior art, and the molten resin is filled from the sprue through the runner groove 47 into the cavity 45.

  At this time, since the head 23b of the tip 23a of the needle pin 23 is exposed to the runner groove 47 from the opening / closing port 21b, a high injection pressure is applied to the tip. However, since the area of the head 23b is small as described above, the air cylinder 22 can sufficiently withstand the pressure and suppress the retraction of the needle pin. Although not shown in the figure, a bolt is screwed into the mold apparatus, and the hollow cylindrical portion 21 is strongly pushed into the insertion hole. Thus, the bottom 46 b of the insertion hole 46 a is in close contact with the distal end surface 21 d of the hollow cylindrical portion 21.

  After completion of filling, the process proceeds from the holding pressure process to the cooling process as usual, and the molten resin is solidified to form a molded product. Next, the molded product is ejected and the mold is closed, and the molding process is repeated again in the same manner as described above.

  Since the vacuum suction valve 20 of the present invention is compactly unitized as a small-diameter device, it is only necessary to process a single insertion hole in a mold on which the vacuum suction valve 20 is mounted. Therefore, it is easy to avoid interference with the temperature control piping. In addition, since the vacuum suction valve 20 can be easily detached, its maintainability is excellent. Further, since the vacuum suction valve is compact, it can be attached to any part of the mold as long as a space for attaching the air cylinder can be secured. Therefore, it is possible to attach to the fixed side mold plate 48 of the three plate type.

  In addition, the present invention is advantageous when vacuum suction is performed in molding in which the ratio of the runner volume is higher than the molded product volume. The present invention can also be employed as a vacuum suction means in a conventionally known mold in which an O-ring is embedded in a portion surrounding the cavity on the parting surface to improve airtightness.

It is sectional drawing of the vacuum suction valve of this invention, and the metal mold apparatus with which it was mounted | worn. It is sectional drawing which expands and shows the front-end | tip vicinity of the vacuum suction valve | bulb of FIG. 1, The figure of the upper half of a needle pin has shown the closed state of the opening-and-closing port, and the figure of the lower side half has shown the open state. It is sectional drawing in case the metal mold apparatus with which the vacuum suction valve of this invention was mounted | worn is a 2 plate metal mold | die. It is sectional drawing in case the metal mold apparatus with which the vacuum suction valve of this invention was mounted | worn is a 3 plate metal mold | die. It is sectional drawing of the conventional shaping | molding apparatus.

Explanation of symbols

20 Vacuum suction valve 21 Hollow cylindrical portion 21b Opening and closing port 21c Inner hole of opening and closing port 21d Tip end surface of hollow cylindrical portion (tip of vacuum suction valve)
22 Air Cylinder 22a Exhaust Port 23 Needle Pin 23a Needle Pin Tip 25 Ventilation Path 30 Vacuum Suction Device 40 Mold Device 41 2 Plate Mold Device 42 3 Plate Mold Device 46 Movable Side Plate 46a Insertion Hole 46b Insertion Hole 46b Bottom 47 Runner groove 48 Fixed side template 48a Insertion hole 48b Bottom of insertion hole PL Parting surface

Claims (1)

A hollow cylindrical portion, and a needle pin that moves in the axial direction in the hollow cylindrical portion by an air cylinder fixed to the proximal end side of the hollow cylindrical portion,
The hollow cylindrical portion has an air passage for allowing air to pass between the inner periphery thereof and the outer periphery of the needle pin, an exhaust port connected to a vacuum suction device for vacuum-sucking air on the proximal end side thereof, and an end thereof An opening that opens on the side of the air passage to the distal end surface of the hollow cylindrical portion,
The inner hole of the opening / closing port and the tip of the needle pin are formed on a taper surface that is substantially the same tapered toward the tip.
A mold apparatus including a vacuum suction valve that performs an opening / closing operation of the opening / closing port by an operation of abutting and separating the tip of the needle pin from the opening / closing port,
The vacuum suction valve is mounted in a posture along the parting surface of the mold apparatus,
By allowing the front end surface of the hollow cylindrical portion to be in close contact with the bottom of the insertion hole of the hollow cylindrical portion and allowing the opening / closing port to communicate with the runner groove of the mold device,
2. A mold apparatus according to claim 1, wherein the runner groove is vacuum-suckable by the vacuum suction valve.

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