JP2014213573A - Air vent valve device and injection molding mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air vent valve device of an injection molding mold which causes no molded product failure.SOLUTION: An air vent valve device 1 includes: a valve which includes a valve head 7 having a reverse circular truncated cone shape, and a valve barrel 8 having an axis common to an axis of the valve head and extending from a smaller circular part in the reverse circular truncated cone shape; an energizing member 6 which energizes the valve in a projecting direction; a molten substance storage chamber 5 which stores a flowing molten substance and in which the valve head is exposed; and a molten substance flow passage which is formed by providing an opening part 20, which allows the inflow of the molten substance into the molten substance storage chamber 5, so as to locate the opening part 20 above the valve head 7.

Description

  The present invention relates to an air vent valve device and an injection mold, and more particularly, an air vent valve device capable of removing residual air inside the mold and possibly a gas component generated from a molten material from a cavity, and The present invention relates to an injection mold that does not cause a molded product defect due to residual gas.

  A mold is known as an apparatus for injection molding of a molten material, and an air vent valve apparatus is known as an air vent apparatus inside the mold.

The mold includes a multi-cavity mold for injection molding a large number of molded products at once.
The multi-cavity mold includes a sprue into which the molten material injected from the nozzle of the injection molding machine flows, a runner branched from the sprue and into which the molten material transferred through the sprue flows, and in the middle of the runner A plurality of branch runners into which the molten material transferred by the runner flows, a cavity provided at the tip of the branch runner for receiving the molten material, and an air vent valve for removing air existing in the cavity, sprue and runner Device.

  When the molten material is injected and a molded product is molded using the mold, if there is air remaining inside the mold, the following two problems arise. First, the pressure required to press the molten material into the mold is increased. Next, the air remaining in the cavity becomes hot by being compressed by the inflowing molten material, the molded part around the compressed air is denatured by heat, and the molded product is burnt black and burned. It becomes a non-defective product.

  Further, when a high-temperature molten material is formed, a decomposition product of the molten material, an additive in the molten material, moisture, and the like are volatilized and gasified. If this gas is not discharged during molding, the residual gas becomes a solid after cooling and adheres to the inner surface of the cavity. Deposits adhered to the inner surface of the cavity may deteriorate the quality of the molded product, for example, by adhering to the surface of the molded product. Therefore, degassing of the mold is essential for improving the quality of the molded product. When the degassing in the mold is not sufficient, not only a defective molded product is formed, but also the frequency of performing maintenance such as cleaning the cavity inner surface increases.

  Furthermore, if the gas generated from the air or molten material remaining inside the mold is not discharged outside the mold during the injection molding, bubbles may remain inside the manufactured molded product, resulting in a cavity. is there. Cavities caused by bubbles generated inside the molded product cause a decrease in strength or destruction of the product. Therefore, a molded product having bubbles inside is a defective product. Except in the case of a transparent molded product, the bubbles inside the molded product cannot be confirmed from the appearance of the molded product surface. In order to detect a defective molded product, it is necessary to perform an inspection using X-rays. Therefore, it is a heavy burden for the manufacturer of the molded product to perform the inspection for finding defective products.

  Conventionally, as a technology of a valve device in a mold, Patent Document 1 discloses that “a sliding member that receives a pressing force by an elastic body from a facing surface side, a bottomed hole formed in a flow direction of a molten material, and the A sliding member having at least one side opening that communicates with the bottomed hole and opens in a direction intersecting the flow direction of the molten material, and slides the sliding member in a direction parallel to the flow direction of the molten material The direction in which the sliding member communicates with the side opening of the sliding member in an initial state where the molten material is received and is not subjected to the flow pressure of the molten material, and then the sliding member resists the elastic body by the flow front end of the molten material A gas release structure in a mold comprising a sliding member receptor having a gas discharge port that is closed when being slid into the mold ”(Claim 1) is disclosed, and“ inside the mold according to the present invention ”is disclosed. The gas release structure is injection molding, die-casting In the indispensable metal mold, etc., it is mounted in the middle of the molten material flow path located on the side far from the gate or in the vicinity of the end of the molten material flow tip, which is subjected to a pressing force by the molten material flow front end ”(paragraph 0019). Has been.

The gas release structure described in Patent Document 1 receives the sliding member 10 so that the outer peripheral surface of the sliding member 10 and the inner peripheral surface of the sliding member receiver 20 can slide. Since it is housed in the body 20, when the front end surface of the high-temperature molten material comes into contact with the front surface of the sliding member 10, due to thermal expansion of the sliding member 10, the outer peripheral surface of the sliding member 10 and the sliding member 20. The inner peripheral surface of this is in close contact. As a result, the sliding member 10 may not be able to slide smoothly with respect to the sliding member receiver 20.
Further, when the sliding member 10 cannot slide smoothly with respect to the sliding member receiver 20, the molten material enters the bottomed hole 12 formed in the sliding member 10, and finally the sliding member 10 slides. There is a risk that the molten material flows out from the gas discharge port 21 formed in the moving member receiver 20.
Such a fear is that the sliding member described in Patent Document 1 is slidably mounted on the sliding member receiver, and a bottomed hole is formed on the front surface of the sliding member. This is considered to be due to the fact that the side opening 13 communicates with the side opening 13 and the side opening 13 communicates with the gas discharge port 21.

  Patent Document 2 states that “in a resin molding die air vent for discharging the gas in the cavity formed by the resin molding die to the outside of the resin molding die when the resin is filled, the air vent has a cylindrical shape. A fixed portion and a movable pin that is provided in one opening of the fixed portion so that the opening can be opened and closed and biased in the opening direction, and the upper surface of the movable pin is a cavity surface when the one opening is closed. The fixed portion is embedded in the cavity surface so that the other opening communicates with the outside of the resin mold, and when there is a gas around the movable pin, the gas is passed through the one opening. Disclosed is an air vent for a resin mold characterized in that the movable pin closes the one opening when discharged from the resin mold and the resin contacts the movable pin (Claim 1). Yes.

  Here, the air vent of Patent Document 2 is attached to the resin mold so that the upper surface of the movable pin faces the cavity surface. Therefore, since this air vent is mounted for each cavity, for example, in a multi-cavity mold, it is necessary to provide an air vent for each cavity mounted on the mold. Therefore, in the air vent described in Patent Document 2, the structure of the mold becomes complicated, and the mold design becomes complicated. Moreover, since it processes so that an air vent can be installed in each of a cavity, there exists a problem that the cost of a metal mold | die also increases.

  Further, in the air vent of Patent Document 2, since the upper surface of the air vent and the lower surface of the flow path of the melt in the cavity are substantially in a straight line, when the resin actually flows into the air vent, the resin Before the opening is closed by pushing, the melt flows into the opening, causing burrs in the molded product, and further, there is a problem that the movable pin cannot move. On the other hand, in order to solve this problem, it is conceivable to reduce the gap between the fixed portion and the opening, but in that case, there is a problem that air bleeding in the mold becomes insufficient. To do.

Japanese Patent No. 4455676 JP 2001-162625 A

  The present invention eliminates such problems and ensures that the residual air inside the mold and possibly the gas components generated from the molten substance are generated without causing the molten substance to leak from the gaps and causing burrs in the molded product. Another object of the present invention is to provide an air vent valve device that can be discharged from a cavity before molding, and another invention eliminates the need to install an air vent valve device for each cavity, and is generated from residual air inside the mold and possibly a molten material. It is an object of the present invention to provide an injection mold that does not cause defective molded products due to the gas component to be produced.

Means for solving the problems of the present invention are as follows:
(1) An air vent valve device that vents air from a mold attached to an injection molding machine,
A valve body having a valve body head having an inverted frustoconical shape, and a valve body body having an axis common to the axis of the valve body head and extending from a small circle in the inverted frustoconical shape;
A valve body housing portion into which the valve body body portion is inserted; and
A valve body head housing chamber having a frustoconical circumferential side surface adjacent to the valve body housing portion and having the same inclination angle as the inverted truncated cone shape of the valve body head,
A molten material storage chamber formed adjacent to the valve head storage chamber, storing the flowing molten material, and exposing the valve head;
An urging member that urges the valve body in a direction in which the valve body head projects into the molten substance storage chamber;
When it is assumed that the valve body head housing chamber has an opening that allows molten material to flow in and the axis of the valve body is in a vertical direction, the opening is above the valve body head. A molten material flow path provided to be located in
An air vent valve device characterized by having
(2) An injection mold having a cavity for receiving a molten resin supplied from an injection molding machine,
A sprue into which the molten material injected from the nozzle of the injection molding machine flows, a runner continuous with the sprue, a plurality of branch runners provided in the runner, and a tip of the runner in the inflow direction of the molten material, or the above An injection mold having the air vent valve device according to (1) connected to a branch runner located farthest from a sprue.

  In the air vent valve device of the present invention, a part or the whole of the valve body head normally protrudes into the valve body head housing chamber by the urging member. A gap is formed between the circumferential side surface and the frustoconical circumferential side surface in the valve head housing chamber. When performing the injection molding, when the molten material is pushed out to the runner, the air present in the runner and the air present in the branch runner are pushed out, and the pressure of the air inside the mold is temporarily increased. The air whose pressure is increased inside the mold is discharged to the outside of the mold at a high speed in the air vent valve device. According to Bernoulli's theorem, the higher the fluid velocity, the smaller the pressure of the air. Therefore, the pressure of the air flowing at high speed in the air vent valve device becomes smaller than the air inside the mold. Therefore, the air inside the mold is sucked into the air vent valve device by negative pressure, and the air existing in the runner, the branch runner and the cavity is discharged out of the mold through the gap. The air vent valve device is connected to a position of the runner farthest from the sprue, that is, a tip position of the runner in the flow direction of the molten material normally flowing in the runner, or a plurality of branches branching from the runner. The runner is connected to the tip of the branch runner that is connected to the farthest position from the sprue, so that the injected molten material can reach the cavity and the air vent valve device before the air in the mold. In some cases, the gas generated from the molten material can be discharged outside the mold.

  On the other hand, when the molten material moving at a high speed in the runner flows from the molten material flow passage into the molten material containing chamber through the opening, the opening portion is the valve when the central axis of the valve body is assumed to be vertical. Since the tip of the molten material that has flowed in always comes into contact with the valve head, and the pressure on the basis of the amount of the molten material that flows in causes the valve head to be attached to the biasing member. It is pushed into the valve head storage chamber against the force. The inverted frustoconical circumferential side surface of the valve body head pushed in by the molten material still supplied to the molten material accommodation chamber and the frustoconical circumferential side surface of the valve body head accommodation chamber are in close contact with each other. Due to the close contact between the inverted frustoconical circumferential side surface and the frustoconical circumferential side surface, air venting is completed, and the molten substance does not leak out of the mold through the gap. Since the air venting is completed, the molten material is pressed into the cavity by the flow pressure of the molten material. Therefore, an injection molded product free from voids and chips is formed.

FIG. 1 is a longitudinal sectional view showing an example of an air vent valve device of the present invention, in which a valve body is not subjected to a pressing force of a molten material, and a peripheral side surface portion of an inverted truncated cone in a valve body head, and a valve body head The state in which the gap | interval is formed between the truncated cone periphery side surfaces of a part storage chamber is shown. FIG. 2 is a longitudinal sectional view showing an example of the air vent valve device of the present invention, in which the valve body receives the pressing force of the molten material, the peripheral side surface portion of the inverted truncated cone in the valve body head, and the valve body head The state where the frustoconical circumferential side surface of the storage chamber is in close contact is shown. FIG. 3 is a schematic diagram showing an example of an attachment position of the air vent valve device in the mold.

  As shown in FIG. 1, an air vent valve device 1 which is an example of the present invention includes a valve body 2, a valve body housing portion 3, a valve body head housing chamber 4, a molten substance housing chamber 5, and an urging member 6. Have

  The valve body 2 includes a valve body head 7 and a valve body body 8 formed integrally with the valve body head 7. The valve body head 7 is formed in the shape of an inverted truncated cone having a large circle portion 9, a small circle portion 10, and a peripheral side surface portion 11 of the inverted truncated cone. The great circle part 9 in the valve body head 7 is also a distal end surface of the valve body head 7, and the distal end surface which is the great circle part is a flat curved surface curved in a convex or concave shape. Also good. From the viewpoint of ease of processing, it is preferable that the tip surface which is a great circle portion is a flat surface. The valve body head portion 7 and the valve body body portion 8 can be integrally formed so as to have a common central axis. That is, the valve body head 7 and the valve body body 8 may be manufactured as an inseparable integral part. However, the valve body head 7 and the valve body body 8 are formed separately, and the separately formed valve body head 7 and the valve body body 8 are integrated by appropriate coupling means such as bolts and screw holes. The valve body 2 can also be used. The valve body body 8 is formed in a cylindrical body having the same diameter as that of the small circle part 10 extending from the small circle part 10 in the valve body head 7. A stopper 12, for example, a nut that protrudes from the outer peripheral surface of the valve body body 8 in the diameter direction of the valve body body 8 is provided on the outer periphery of the valve body body 8. The valve body 2 can employ various materials as long as it has heat resistance to the temperature of the molten material and has an appropriate strength under use conditions, and is usually made of metal.

  The valve body housing part 3 has an inner surface that forms a space for housing the valve body body part 8. In addition, the inner surface of the valve body housing portion 3 includes a small-diameter inner peripheral surface 13 and a valve body body portion 8 that are opposed to the outer surface of the valve body body portion 8 from the small circle portion 10 of the valve body head portion 7 to a predetermined portion. And a large-diameter inner peripheral surface 14 facing the outer peripheral surface from the predetermined portion to the rear end portion of the valve body barrel 8. The diameter of the small-diameter inner peripheral surface 13 of the valve body housing portion 3 is determined so that a gap is formed between the small-diameter inner peripheral surface 13 of the valve body housing portion 3 and the outer peripheral surface of the valve body body portion 8. Further, the diameter of the large-diameter inner peripheral surface 14 of the valve body accommodating portion 3 is determined so that a gap is formed between the large-diameter inner peripheral surface 14 of the valve body accommodating portion 3 and the outer peripheral surface of the valve body trunk portion 8. . The diameter of the large-diameter inner peripheral surface 14 in the valve body housing 3 is larger than the diameter of the small-diameter inner peripheral surface 13. Therefore, a step portion is formed by the small diameter inner peripheral surface 13 and the large diameter inner peripheral surface 14. Further, the stepped portion is formed in a disk surface shape when the small diameter inner peripheral surface 13 is viewed from the large diameter inner peripheral surface 14, and a notch-shaped gas escape groove 15 is provided on the disk surface in the stepped portion, Preferably, 4 to 6 gas escape grooves 15 are provided on the circumference. As shown in FIG. 1, even when the stopper 12 abuts on the disk surface of the stepped portion and the stopper 12 is locked to the stepped portion, the gas escape grooves 15 provided at a plurality of locations on the disk surface of the stepped portion are used. Thus, the air in the mold can be discharged to the outside. As long as the air in the mold can be discharged to the outside, the depth and length of the gas escape groove 15 can be changed as appropriate.

  In the state in which the valve body barrel 8 is housed in the valve body housing 3, an air discharge hole 16 is formed in the inner wall surface of the valve body housing 3 toward which the end surface of the valve body body 8 faces, and the urging member 6 For example, a coil spring is attached. The gas in the valve body housing part 3 is discharged from the air discharge hole 16. The number, size, and the like of the air discharge holes 16 provided in the inner wall surface of the valve body housing 3 are as long as the residual air inside the mold and the gas components generated from the molten material can be discharged from the cavity before injection molding. It is possible to change freely.

  One end of the urging member 6 is coupled to the inner wall surface of the valve body housing 3 toward which the rear end surface of the valve body body 8 faces, and the other end of the urging member 6 is coupled to, for example, the rear end surface of the valve body body 8. Is done. Therefore, the valve body 2 is urged so as to protrude from the valve body housing portion 3 to the outside. The stopper 12 provided on the outer peripheral surface of the valve body body 8 is locked to the stepped portion so that the valve body 2 itself does not come out of the valve body housing 3. In addition, as long as the urging force is applied so that the valve body 2 protrudes from the valve body housing portion 3 to the outside, the coupling position of the urging member 6 can be changed in design. As the coupling position, for example, one end of the urging member 6 is coupled to the inner wall surface of the valve body housing 3 toward the rear end surface of the valve body body 8, and the other end of the urging member 6 is the lower end surface of the stopper 12. It is mentioned to couple | bond with.

  In the example shown in FIG. 1, the stopper 12 is locked to the step formed by the small-diameter inner peripheral surface 13 and the large-diameter inner peripheral surface 14, so that the valve body 2 itself is the valve body accommodating portion 3. Although it is formed so as not to come out of the valve body 2, the design change is not limited to the mechanism by the combination of the stopper 12 and the step as long as the valve body 2 itself can be prevented from coming out of the valve body housing portion 3. Other mechanisms can be employed. For example, as a design change that prevents the valve body 2 itself from coming out of the valve body housing portion 3, the entire inner peripheral surface along the central axis direction of the valve body housing portion 3 is made a small diameter inner circumferential surface, and the small diameter inner circumferential surface is formed. A key groove provided in a certain length along a direction parallel to the central axis direction of the valve body 2, and a key that slides in the key groove and is provided on the peripheral surface of the valve body body 8. As an example, a mechanism that prevents the valve body 2 from coming out of the valve body housing portion 3 by blocking the key fitted into the key groove at the end face of the key groove can be given.

  Various materials can be adopted as the material for forming the valve body housing portion 3 as long as the material has heat resistance and has an appropriate strength under use conditions, and is usually made of metal.

  The valve body head housing chamber 4 is formed continuously with the small-diameter inner peripheral surface 13 in the valve body housing portion 3, in other words, is formed adjacent to the valve body housing portion 3. The valve head housing chamber 4 includes a small diameter portion 17 having the same diameter as the small diameter inner peripheral surface 13, a large diameter portion 18 having a diameter larger than the diameter of the small diameter portion 17, the small diameter portion 17 and A frustoconical circumferential side surface 19 is formed to communicate with the large diameter portion 18. The length in the central axis direction from the small-diameter portion 17 to the large-diameter portion 18 is such that the frustoconical circumferential side surface 19 and the circumferential side surface portion 11 of the inverted truncated cone in the valve body head 7 come into contact with each other. As long as the valve body accommodating portion 3 can be shut off in an airtight manner, it can be determined as appropriate. For example, when the frustoconical circumferential side surface 19 and the circumferential side surface portion 11 of the valve body head 7 are in contact with each other, the large-diameter portion 9 of the valve body head 7 has a small diameter so as to be positioned in the valve body head housing chamber 4. The length in the central axis direction from the portion 17 to the large-diameter portion 18 may be determined, and the large-circular portion 9 of the valve body head 7 may coincide with the large-diameter portion 18 in the valve body head housing chamber 4. Further, the length in the central axis direction from the small diameter portion 17 to the large diameter portion 18 may be determined, and from the small diameter portion 17 so that the large circle portion 9 of the valve body head 7 is located in the molten substance storage chamber 5. The length in the central axis direction to the large diameter portion 18 may be determined.

  The inclination angle of the truncated cone peripheral side surface 19 in the valve body head accommodating chamber 4 and the inclination angle of the circumferential side surface portion 11 of the inverted truncated cone in the inverted truncated cone shape in the valve body head 7 are the same. Since the inclination angle of the frustoconical circumferential side surface 19 in the valve body head accommodating chamber 4 and the inclination angle of the circumferential side surface portion 11 of the inverted truncated cone in the valve body head 7 are the same, the reverse cone in the valve body head 7 When the peripheral side surface portion 11 of the base and the peripheral side surface 19 of the truncated cone come into contact with each other, the valve body head portion 7 shuts off the valve body storage portion 3 and the molten substance storage chamber 5 in an airtight manner. The inclination angle between the peripheral side surface portion 11 and the peripheral side surface portion 19 of the inverted truncated cone, the length in the central axis direction, the surface area of the inclined portion, and the like are determined based on the residual air in the mold and the material obtained by gasifying the molten material. As long as it can be discharged to the outside and that the valve body 2 can be reciprocated along the central axis direction by thermal expansion of the members constituting the air vent valve device 1 as appropriate, The design can be changed.

  Various materials can be adopted as the material for forming the valve head housing chamber 4 as long as it has heat resistance and has an appropriate strength under use conditions, and is usually made of metal.

  The molten material storage chamber 5 has an inner surface that communicates with the valve body head storage chamber 4 and forms a space in which the molten material can be stored. In the state of FIG. 1 in which the valve body 2 is not subjected to the pressing force by the molten substance, the front end surface which is the great circle portion 9 of the valve body head 7 faces the internal space of the molten substance storage chamber 5. The molten substance storage chamber 5 is provided with an opening 20 for a molten substance flow passage. The molten material flow passage having the opening 20 is connected to the tip of the runner 22 in the inflow direction of the molten material connected to the sprue 21 into which the molten material injected from the nozzle of the injection molding machine flows or to the runner 22. Of the plurality of branch runners 23 provided, the branch runner 23 is coupled to the branch runner 23 located farthest from the sprue 21. Since an injection molding machine is provided upstream of the opening 20, air in the mold, a gaseous substance generated from the molten substance, or a molten substance flows from the opening 20 into the molten substance storage chamber 5. To do. As the material forming the molten substance storage chamber 5, various materials can be adopted as long as the material has heat resistance and has an appropriate strength under use conditions, and is usually made of metal.

  The position where the opening 20 is opened is higher than the front end surface of the valve body head 7 when the posture of the air bleeding valve device is assumed so that the central axis direction of the valve body 2 is vertical. To be determined. Since the melted material has viscosity and surface tension, the melted material flowing through the melted material flow passage becomes a full head from the opening 20 and flows into the melted material storage chamber 5 to become a full head. Thus, the molten material flows between the peripheral side surface portion 11 of the inverted truncated cone in the valve body head 7 and the peripheral surface 19 of the truncated cone in the valve head housing chamber 4. Prior to entering, the molten material causes the valve body head 7 to recede against the biasing force of the biasing member 6. In addition, when the posture of the air vent valve device is assumed so that the central axis direction of the valve body 2 is a vertical direction, “retraction of the valve body head 7” should be described as “pushing down the valve body head 7”. Can do. The position of the opening 20 is such that the molten material resists the urging force of the urging member 6 before the molten material enters between the peripheral side surface portion 11 and the circular truncated cone side surface 19 of the inverted truncated cone. As long as the valve head 7 can be retracted, the design can be changed as appropriate.

  Even when the posture of the air bleeding valve device is assumed such that the central axis direction of the valve body 2 is in a direction other than the vertical direction, for example, the central axis direction of the valve body 2 is in the horizontal direction, The melted material that has flowed into the melted material storage chamber 5 reaches the tip surface of the valve body head 7 so that the melted material is further supplied to the melted material storage chamber 5. As a result, the molten material presses the valve body head 7 and retracts the valve body head 7 against the biasing force.

  The design of the angle of the central axis of the valve body 2 can be changed as appropriate depending on the type of substance to be injection-molded. When the molten material has a relatively high viscosity, it is preferable to adjust the attitude of the air vent valve device so that the central axis of the valve body 2 is in the vertical direction. Examples of the substance having a relatively high viscosity in a molten state include an organic polymer resin, for example, an organic polymer resin having a melt viscosity of 1 to 200 Pa · S. Further, when the molten material has a relatively low viscosity, the posture of the air vent valve device may be adjusted so that the central axis of the valve body 2 is in the horizontal direction. Examples of the substance that is in a relatively low-viscosity molten state include aluminum having a melt viscosity of 0.0001 to 0.001 Pa · S.

  FIG. 3 is an explanatory view showing a position where the air vent valve device according to the present invention is provided in the injection mold.

  The injection mold includes a sprue 21 into which molten material injected from a nozzle flows, a runner 22 connected to the sprue 21, a plurality of branch runners 23 provided in the runner 22, and a cavity 24 for receiving the molten material. And an air vent valve device 1.

The injection mold can be made of various materials or materials as long as it is not modified or deformed by the heating temperature necessary for melting the resin to be injection molded, and is usually made of metal.
The sprue 21 is a molten material flow path through which the molten material injected from the nozzle of the injection molding machine reaches the runner 22, and is usually arranged so that the molten material flows vertically downward, and is orthogonal to the axial direction of the flow path. It is a distribution space in which the cross section to be formed is a circle. When the cross-sectional shape of the sprue 21 is circular, the circular diameter is usually 7 to 8 mm. The sprue 21 is usually adjusted so that its inner diameter increases from the injection molding machine side toward the runner 22 side, and more preferably has a tapered shape of 3 to 5 °.

  The runner 22 is an inflow path of a molten material that is continuous with the sprue 21 and extends from the sprue 21 to the branch runner 23. The runner 22 is a molten material flow path that is normally provided in a horizontal direction with respect to the sprue 21 arranged vertically downward, and a cross section in a direction orthogonal to the axial direction of the runner 22 is circular or trapezoidal. In the multi-cavity mold, the number of runners 22 branched from the sprue 21, the length in the direction of the central axis, as long as the runners 22 are arranged so that the molten material flows into the plurality of cavities simultaneously and evenly, The design of the diameter and the like can be changed as appropriate. The preferred number of runners 22 branching from the sprue 21 is two. The material of the runner 22 varies as long as it is not denatured even under high temperature conditions, and is usually made of metal.

The branch runner 23 is an inflow path of a molten material that is provided in the middle of the runner 22 and reaches the cavity 24. The branch runner 23 includes a first branch path that branches from the runner 22 in a direction perpendicular to the axis line of the runner 22 on a plane that includes the axis line of the runner 22 and is orthogonal to the axis line of the sprue 21, A second branch path that is perpendicular to the first branch path in the plane at the tip and branches in two directions opposite to each other; a direction perpendicular to the plane from the second branch path; The flow path has a third branch path extending downward, and the cross section of the flow path is circular. In the multi-cavity mold, a plurality of branch runners 23 branch from the middle part of the runner 22. The branch runner 23 preferably has a tapered shape in which the cross-sectional diameter gradually decreases toward the cavity in the vertically extending portion.
In the multi-cavity mold, the number of branches of the branch runner 23, the length in the central axis direction, the size of the diameter, etc. are appropriately set as long as the molten material can flow uniformly into the plurality of cavities 24. The design can be changed. Various materials can be adopted as the material of the branch runner 23 as long as the material is not denatured even under high temperature conditions, and is usually made of metal.

  The cavity 24 has a concave space in which the outer shape of the molded product is modeled on the inner surface thereof, and the molten material flowing from the branch runner 23 is cooled and solidified inside the cavity 24, whereby the molded product is completed. The size, shape, and the like of the cavity are appropriately changed depending on the type of the molded product. The cavity 24 is usually made of metal.

The tip of the runner 22 or the branch runner 23 is connected to the opening 20 of the air vent valve device 1. The molten material pushed out from the sprue 21 reaches the opening 20 through the runner 22 or the branch runner 23, and the air in the mold also reaches the opening 20 through the runner 22 or the branch runner 23. .
The air vent valve device 1 is connected to a tip of the runner 22 in the inflow direction of the molten material, or to a branch runner 23 that is farthest from the sprue 21. In other words, the air vent valve device 1 is provided at a position of the runner 22 or the branch runner 23 that has the longest path length from the sprue 21 and takes the longest time for the molten material to reach. When a plurality of runners 22 branch from the sprue 21, at least one air vent valve device 1 is provided for each system of the branched runners 22. In FIG. 3, the example in which the air vent valve apparatus 1 is provided in the both ends in the inflow direction of the molten material of the runner 22 is shown. By providing the air vent valve device 1 at such a position, the time for the injected molten material to reach the air vent valve device 1 through the sprue 21 and the runner 22, and the molten material is sprue 21, the runner 22, The time for the air in the cavity 24, the branch runner 23, and the runner 22 to reach the air vent valve device 1 due to the negative pressure is shorter than the time to reach the cavity 24 through the branch runner 23. Therefore, before the molten material reaches the air vent valve device 1 and before the molten material reaches the cavity 24, the air in the mold and the gas generated from the molten material are removed from the mold through the air vent valve device 1. Therefore, it is possible to prevent defective molding due to residual air.

  The air vent valve device 1 may be formed integrally with the runner 22 or the branch runner 23. After the air vent valve device 1 and the runner 22 or the branch runner 23 are separately formed, the air vent valve device 1 is used as the runner. However, it is desirable to form the air vent valve device 1 and the runner 22 or the branch runner 23 separately in consideration of the maintenance of the air vent valve device 1 and the ease of parts replacement. As a method of attaching the air vent valve device 1 to the runner, a method of connecting the runner pipe and the vicinity of the opening 20 of the air vent valve device 1 by a flange joint, or a connection portion of the runner and the opening of the air vent valve device 1 A specific example is a method in which a cut is provided on the inner surface of the vicinity of 20 and a connection is made by tightening into a screw shape.

  In the case where the air vent valve device 1 of the present invention is used in a so-called single die that molds only one product in a single injection process, the mounting position of the air vent valve device 1 is claimed. It is not limited to the position described in Item 2, and may be provided on the cavity surface.

  Next, the operation of the air vent valve device and the injection mold according to the present invention will be described.

  In an initial state before the molten material reaches the air vent valve device 1 installed at the end of the runner 22, the valve body 2 protrudes into the molten material storage chamber 5 by the urging force of the urging member 6, and the valve body head A gap is formed by the peripheral side surface portion 11 of the inverted circular truncated cone 7 and the truncated cone peripheral side surface 19 of the valve body head housing chamber 4. In addition, the stopper 12 attached to the outer surface of the valve body barrel 8 is engaged with the stepped portion formed by the small diameter inner peripheral surface 13 and the large diameter inner peripheral surface 14 of the valve body accommodating portion 3, The valve body head 7 is fixed at a predetermined position without protruding too far toward the valve body head housing chamber 5.

  When the injection molding is started, the molten material discharged from the nozzle of the injection molding machine sequentially passes through the sprue 21, the runner 22, and the branch runner 23 and flows into the cavity 24 or the air vent valve device 1. As the molten material is pushed out from the nozzle of the injection molding machine, the pressure of the air inside the mold is temporarily increased. On the other hand, the gap formed by the peripheral side surface portion 11 of the inverted truncated cone and the truncated cone side surface 19 in the air vent valve device 1 is a cross-sectional area of a cross section perpendicular to the air traveling direction as compared to the cross section of the runner 22. Is small. Therefore, the air whose pressure has been increased inside the mold is discharged to the outside of the mold at a high speed in the air vent valve device 1. According to Bernoulli's theorem, the higher the fluid velocity, the smaller the pressure of the air. Therefore, the pressure of the air flowing at high speed in the air vent valve device 1 becomes smaller than the air inside the mold. Therefore, the air generated in the mold and the gas generated from the molten material are sucked into the air vent valve device 1 by the negative pressure. The sucked air is discharged to the outside of the mold through the gap between the peripheral side surface portion 11 and the circular truncated cone side surface 19 of the inverted truncated cone, the gas escape groove 15 and the air discharge hole 16.

  Since the air vent valve device 1 is provided at the tip of the runner 22 in the molten material inflow direction or the branch runner 23 located farthest from the sprue 21, the molten material reaches the air vent valve device 1. Before and before the molten material flows into the cavity 24, the air remaining in the runner 22, the branch runner 23, and the cavity 24 is sucked at a high speed by the air vent valve device 1 and passes through the air discharge hole 16. It is discharged outside the mold. For this reason, molding is performed while air remains in the cavity 24, so that molding defects such as charring do not occur.

  In addition, gas components that may be generated from the molten material are also sucked by the air vent valve device 1 before the molten material reaches the air vent valve device 1 and before the molten material flows into the cavity 24, It is discharged outside the mold through the discharge hole 16. Therefore, the molded product is not contaminated by the gas component remaining inside the cavity 24, and the gas component attached to the inner surface of the cavity is not cooled and solidified to cause deterioration of the inner surface of the cavity.

  Before the molten material is molded, the air in the mold and the gas components generated from the molten material are released to the outside of the mold through the air vent valve device 1, so that the remaining air remains inside the molded product. A void is generated as a bubble and does not cause a defective molded product that causes a decrease in strength or breakage of the molded product.

  Further, before the molten material fills the cavity 24, the residual air and gas components in the mold are discharged to the outside of the mold through the air vent valve device 1, and therefore melt to the end of the cavity 24. The pressing force of the injection molding machine required for filling the substance does not increase.

  After all the residual air and gas components inside the mold are discharged to the outside, the molten material enters the air vent valve device 1 through the opening 20. Since the opening 20 is provided above the distal end surface of the valve body head 7 when the posture of the air vent valve device 1 is assumed so that the central axis direction of the valve body 2 is a vertical direction, The tip of the bulging head of the molten material flows down from the opening 20 toward the great circle portion 9 of the valve device 2, thereby applying a pressing force to the valve body 2. The valve body 2 to which the pressing force is applied moves backward against the urging force of the urging member 6, and the peripheral side surface portion 11 of the inverted truncated cone of the valve body head 7 and the valve body head housing chamber The four frustoconical circumferential side surfaces 19 are in close contact with each other. Therefore, after all the air and gas components in the mold are discharged to the outside and the molten material is filled in the mold, the molten material may leak out to the outside of the mold through the air vent valve device 1. There is no burr in the molded product. In addition, the close contact portion is formed by a frustoconical peripheral side surface, and a gap is provided between the valve body body 8 and the valve body housing portion 3, so that a high-temperature molten material is used. Even in this case, the valve body 2 does not slide smoothly due to thermal expansion.

DESCRIPTION OF SYMBOLS 1 Air vent valve apparatus 2 Valve body 3 Valve body accommodating part 4 Valve body head accommodating chamber 5 Molten substance accommodating chamber 6 Energizing member 7 Valve body head 8 Valve body trunk | drum 9 Large circle part 10 Small circle part 11 Reverse cone Peripheral side surface portion 12 Stopper 13 Small diameter inner peripheral surface 14 Large diameter inner peripheral surface 15 Gas escape groove 16 Air discharge hole 17 Small diameter portion 18 Large diameter portion 19 Frustum peripheral side surface 20 Opening portion 21 Sprue 22 Runner 23 Branch runner 24 Cavity

Claims (2)

An air vent valve device that vents air in a mold attached to an injection molding machine,
A valve body having a valve body head having an inverted frustoconical shape, and a valve body body having an axis common to the axis of the valve body head and extending from a small circle in the inverted frustoconical shape;
A valve body housing portion into which the valve body body portion is inserted; and
A valve body head housing chamber having a frustoconical circumferential side surface adjacent to the valve body housing portion and having the same inclination angle as the inverted truncated cone shape of the valve body head,
A molten material storage chamber formed adjacent to the valve head storage chamber, storing the flowing molten material, and exposing the valve head;
An urging member that urges the valve body in a direction in which the valve body head projects into the molten substance storage chamber;
When it is assumed that the valve body head housing chamber has an opening that allows molten material to flow in and the axis of the valve body is in a vertical direction, the opening is above the valve body head. A molten material flow path provided to be located in
An air vent valve device comprising: An injection mold having a cavity for receiving a molten resin supplied from an injection molding machine,
A sprue into which the molten material injected from the nozzle of the injection molding machine flows, a runner continuous with the sprue, a plurality of branch runners provided in the runner, and a tip of the runner in the inflow direction of the molten material, or the above An injection mold comprising the air vent valve device according to claim 1 connected to a branch runner located farthest from the sprue.

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