JP2008265016A - Method of resin molding and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molding method capable of simplifying the whole process by dispensing with the cutting process for a spool and a liner after opening a mold in insert-molding of a rotor body. <P>SOLUTION: A cavity 10 for forming the rotating body 11 having an annular metal member 5 at the center is constituted by a plurality of molds. A boss mold 4 which has a shaft part 41 having the annular metal member 5 externally fitted and a flange part 42 for forming an annular film gate 9 is disposed at the axis center part of the cavity 10, and a molten resin is injected into the cavity 10 from the film gate 9 in such a state that the annular metal member 5 is held by the shaft part 41, and the annular metal member 5 is sandwiched between the flange part 42 and the mold. When curing the resin injected into the cavity 10 under a predetermined pressure, the rotor 11 is separated from the liner 8 by moving the flange part 42 to the liner side and blocking the film gate 9 to open a plurality of molds after curing the resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin molding method and an injection molding apparatus used when insert molding a rotating body (for example, a pulley, a gear, etc.) having an annular metal member (for example, a rolling bearing) at the center.

  Conventionally, as an injection molding apparatus of this type, a plurality of molds that house a rolling bearing as an annular metal member and constitute a cavity for forming a rotating body, and a plurality of molds that support the rolling bearing and the plurality of molds There is known an apparatus having a forming die provided with a boss die for forming a runner and a film gate therebetween (for example, see Patent Document 1).

  In such an apparatus, the melted resin is filled into the cavity through the sprue, and the resin is cured while maintaining a predetermined pressure. Then, after the resin hardened, the mold was opened, and then the resin molded product and the boss mold were pushed with the ejector pins to remove them from the mold.

JP 2001-198953 A

  However, since the resin molded product obtained by the above-described conventional resin molding method or injection molding apparatus has an integrated sprue and runner, a post-process is performed in order to obtain a desired product. The runner had to be cut and separated from the resin molding.

  An object of the present invention is to provide a resin molding method and an injection molding apparatus capable of simplifying the entire process by omitting a sprue and runner cutting process after mold opening in insert molding of a rotating body in view of the above prior art. Is to provide.

  In order to achieve the above object, the resin molding method of the present invention comprises a cavity for forming a rotating body having an annular metal member in the center by a plurality of molds, and the annular metal is formed in the axial center of the cavity. A boss mold having a shaft portion on which the member is fitted and a flange portion forming an annular film gate is disposed, the annular metal member is held by the shaft portion, and the flange portion and the mold The molten metal is injected from the film gate into the cavity with the annular metal member sandwiched therebetween, and the flange portion is moved to the runner side when the resin injected into the cavity is cured under a predetermined pressure. The rotating gate and the runner are separated by blocking the film gate, and the plurality of molds are opened after the resin is cured.

  According to such a configuration, when the flange portion is moved to the runner side during the resin curing, the resin constituting the sprue and the runner is deformed by elastic deformation, and the flange portion blocks the film gate, thereby the rotating body. The constituent resin and the resin of the runner part are divided. Thereafter, curing proceeds in a state where the rotating body and the runner are separated. Therefore, when the plurality of molds are opened after the resin is cured, the rotating body and the combined runner and sprue can be taken out separately, and the conventional post-cutting process can be omitted. it can.

The said structure WHEREIN: It is preferable to comprise so that the said film gate may be interrupted | blocked when the metal mold | die which forms the said film gate between the said flange parts, and the said flange part contact.
According to such a configuration, since the resin in the cavity constituting the rotating body and the resin in the runner portion are separated by shearing, it is difficult for excess resin to remain on the cut surface. Therefore, burrs are less likely to occur in the rotating body obtained after molding.

  An injection molding apparatus according to the present invention for achieving the above object is an injection molding apparatus for forming a rotating body having an annular metal member at the center, wherein the first gold having a sprue along the axis. A mold having a mold and a second mold opposed to the first mold, containing a front annular metal member and constituting a cavity for forming a rotating body, and the annular metal member is externally fitted And a shaft portion in which one end side is removably fitted along the shaft center in a support hole provided in the second mold, an end portion is formed on the other side of the shaft portion, and an inner surface is formed in the annular shape. A flange portion that is in close contact with one end surface of the metal member and forms an annular film gate between the outer peripheral edge portion of the outer surface and the first mold; and the annular metal member is an axis of the cavity The boss mold to be held on the part and this boss mold are moved along the axis. The contacting and separating with respect to the first mold Te by, characterized in that it comprises a boss die moving means for opening and closing the film gate.

  According to the above configuration, when the boss mold moving means brings the boss mold closer to the first mold, the flange portion and the first mold come into contact with each other to block the film gate. The sprue and runner and the rotating body are separated from each other in the mold only by the mold operation. Therefore, the post-process for separating the rotating body from the runner after the mold opening can be omitted.

The said structure WHEREIN: It is preferable that the said boss | mold mold moving means is provided with the pin which can be reciprocated along the axial center of a said 2nd metal mold | die.
According to this configuration, by moving the pin, the boss mold can be easily brought into and out of contact with the first mold, and the film gate can be easily opened and closed.

The said structure WHEREIN: It is preferable that the outer peripheral surface of the flange part in the said boss | mold metal mold | die is comprised so that it can closely fit in the inner peripheral surface of a said 1st metal mold | die.
According to such a configuration, the outer peripheral surface of the flange portion in the boss mold is tightly fitted into the inner peripheral surface of the first mold, so that the film gate is reliably cut off. Therefore, the resin in the cavity constituting the rotating body and the resin in the runner portion are reliably separated.

Moreover, it is preferable that the flange part in the boss mold and the first mold are configured to contact the resin in the vicinity of the film gate so as to be shearable.
According to this configuration, when the flange portion and the first mold come into contact with each other, the resin in the vicinity of the film gate is sheared, so that the resin adheres to the interface between the flange portion and the first mold. hard. Accordingly, it is difficult for burrs to adhere to the rotating body after molding, so there is no need to provide a post-deburring step.

  According to the present invention, since the sprue and the runner and the rotating body are separated only by the mold operation in the mold when the rotating body is insert-molded, the process can be simplified with a simple configuration. .

Hereinafter, an embodiment of a resin molding method and an injection molding apparatus according to the present invention will be described with reference to the drawings, taking as an example the production of a resin pulley 11 as a rotating body.
FIG. 1 is an explanatory cross-sectional view of a main part of an injection molding apparatus according to an embodiment of the present invention. This injection molding apparatus includes a movable mold 3 and a fixed mold 2. The movable mold 3 includes a movable cavity mold 33 as a second mold for forming the disk surface 51 and the like of the resin pulley 11 and a V-groove-shaped section 52 of the resin pulley 11 that becomes an undercut portion during molding. And a pair of slide cavity molds 31 are formed.
On the other hand, the fixed-side mold 2 includes a sprue bush 20 in which a sprue 7 serving as a flow path for injecting resin is formed along the axial center thereof, and is disposed adjacent to the sprue bush 20 and serves as an annular metal member. A fixed cavity as a first mold that is arranged to face the movable cavity mold 33 via the rolling bearing 5 and continuously forms the sprue 7, the runner 8, the disk surface 51 of the resin pulley 11, and the like. A mold 21 is provided. A pair of angular pins 22 for opening and closing the above-described slide cavity mold 31 is fixed to the fixed mold 2.

Between the fixed cavity mold 21 and the movable cavity mold 33, a boss mold 4 that supports the rolling bearing 5 and forms a runner 8 and a film gate 9 between the fixed cavity mold 21. Is arranged. More specifically, the boss die 4 has a shaft portion 41 fitted with a rolling bearing 5 constituting the resin pulley 11 so that the boss die 4 can be attached to and detached from a support hole 34 provided in the movable cavity die 33. Inserted. Thus, the rolling bearing 5 is supported at the center of the cavity 10 of the mold. A flange portion 42 is integrally formed radially outward at one shaft end of the shaft portion 41, and an inner side surface of the flange portion 42 receives the rolling bearing 5 in close contact. And the annular film gate 9 which inject | pours molten resin radially outward from the outer peripheral end surface side of the rolling bearing 5 between the outer-periphery edge part of the outer side surface of the said flange part 42, and the said fixed side cavity type | mold 21. Is formed.
The cavity 10 filled with the resin includes the boss mold 4, the slide cavity mold 31, the movable side cavity mold 33, and the fixed side cavity mold 21.

  As shown in FIGS. 1 to 3, the injection molding apparatus according to the present embodiment includes ejector pins 61 a and 61 b for projecting a molded resin pulley 11 from a molding die, and tip portions of the ejector pins 61 a and 61 b inside the shaft portion 41. And a gate cutting pin 70 as a boss mold moving means locked to the peripheral surface. These pins 61a, 61b, and 70 have a protruding end bar (FIG. 1) to which a base end portion of the pin 61a, 61b, 70 is connected to a vertical driving means (for example, a hydraulic cylinder) attached to the injection molding apparatus in FIGS. (Not shown) is integrally attached to a protrusion plate 62 (62a, 62b) that is interlocked with it. The ejector pins 61a and 61b move up and down in accordance with the vertical movement of the protruding plate 62a. When the ejector pins 61a and 61b move upward in the drawing, the ejector pins 61a and 61b are fixed on the fixed side by pushing up the pulley portion of the adjacently disposed rolling bearing 5. Push it up to the mold 2 side. The gate cutting pin 70 moves up and down in accordance with the up and down movement of the protruding plate 62 b, thereby causing the boss mold 4 to move along the axis of the movable cavity mold 33 and the fixed cavity mold 21 in the cavity 10. Approaches or moves away from the fixed cavity mold 21. Further, a center pin 60 is disposed in the shaft center of the gate cutting pin 70 and the boss die 4 so as to penetrate through the shaft cutting pin 70 and the boss die 4 and to project the tip portion toward the runner 8 side.

The outer peripheral surface of the flange portion 42 of the boss mold 4 is configured to be closely fitted into the inner peripheral surface of the fixed-side cavity mold 21. Accordingly, when the gate cutting pin 70 is driven upward in FIGS. 1 to 3 to bring the boss die 4 closer to the fixed-side cavity die 21, the peripheral portion of the outer peripheral surface of the flange portion 42 is The annular film gate 9 is cut off in contact with the inner peripheral surface of the fixed cavity mold 21.
As shown in FIG. 2, at the start of molding, the movable side mold 3 and the fixed side mold 2 are closed, and the boss mold 4 is in close contact with one side surface of the rolling bearing 5 (side surface on the fixed side cavity mold 21 side). Is in a state. At the time of molding, the resin is injected into the cavity 10 from the nozzle of the injection molding device through the sprue 7 in the sprue bush 20, the runner 8 communicating with the sprue 7, and the film gate 9. After the injected resin is filled in the cavity 10, the resin pressure in the cavity 10 is increased to a predetermined pressure. Subsequently, the pressure holding state is maintained at a predetermined pressure for a predetermined time. At this time, curing of the resin in the film gate 9 portion starts.
As shown in FIG. 3, when the resin curing of the film gate 9 proceeds, the gate cutting pin 62b is moved upward by driving a hydraulic cylinder (not shown) to move the gate cutting pin 62b. The film gate 9 is blocked by the inner peripheral surface of the fixed-side cavity mold 21 and the outer peripheral surface of the flange portion 42 by pushing up the 70 and the boss mold 4 locked thereto. Then, the resin pulley 11 molded in the cavity 10 is separated from the resin on the sprue 7 and runner 8 side by shearing. Thereafter, curing of the resin proceeds with the resin divided at the film gate 9 portion.

  Further, after holding the resin for a certain period of time to cure or solidify the resin, the movable mold 3 is retracted, and the slide cavity mold 31 is slid to the outside of the mold by the angular pin 32 to form a molded resin pulley. Open the mold until 11 can be removed. Here, since the resin constituting the sprue 7 and the runner 8 part is hardened integrally with the tip of the center pin 60, when the mold is opened, it is integrated with the movable pin 3 side together with the center pin 60. Moving. Therefore, the sprue 7 and the runner 8 do not remain in the fixed side cavity mold 21. Thereafter, as shown exaggeratedly in FIG. 4, the sprue 7 and the runner 8 are separated from the composite body formed by the molded resin pulley 11 and the boss mold 4. Further, the ejection plate 62a is moved by an ejection bar (not shown) attached to the injection molding apparatus, and the ejector pins 61a and 61b are ejected in the fixed side direction (upward in the drawing), whereby the resin pulley 11 and the boss. The mold 4 is removed from the cavity 10. Next, by moving the gate cutting pin 70 in the fixed side direction (upward in the drawing), the boss die 4 can be pulled out from the center hole of the rolling bearing 5 and the resin pulley 11 can be taken out.

  Thus, in the injection molding apparatus of the present invention, the gate cutting pin 70 that reciprocates so that the boss mold 4 approaches or separates from the fixed-side cavity mold 21 is simply connected to the boss mold 4. Further, the device for driving the gate cutting pin 70 can be provided outside the mold in the same manner as the ejector pins 61a and 61b conventionally used for pushing out the molded resin pulley 11. Accordingly, there is a design advantage that such a configuration can be introduced without significantly modifying the structure of the conventional mold.

In FIGS. 2 and 3, the thickness of the film gate 9 is exaggerated for the sake of explanation, but it can be designed thinner.
Further, the timing for blocking and re-releasing the film gate 9 can be changed as appropriate depending on the type of resin and the curing conditions. However, even if the boss mold 4 moves upward as the gate cutting pin 70 moves. It is preferable to move the gate cutting pin 70 at a timing at which the resin existing in the vicinity of the film gate 9 in the cavity 10 has a hardness that does not deform.
In addition, when the film gate 9 is very thin and the resin distortion due to the gate blocking is very small, the resin is cut by the movement of the boss die 4 accompanying the movement of the gate cutting pin 70 after the resin curing is completed. You can also.

  Further, a substantially conical inclined portion that is inclined at an angle parallel to each other is provided on each of the inner peripheral surface of the portion constituting the runner 8 of the fixed-side cavity mold 21 and the outer peripheral surface of the flange portion 42. By driving the gate cutting pin 70, the inclined portion of the outer peripheral surface of the flange portion 42 is closely fitted to the inner peripheral surface of the inclined portion forming the runner 8 of the fixed-side cavity mold 21. Also good.

  The resin material of the resin pulley 11 molded according to the present invention is not particularly limited, but is a resin composition in which a phenolic resin contains a fibrous reinforcing material such as glass fiber, or a resin base material made of a polyamide resin. It is preferable to use a resin composition containing a fibrous reinforcing material and a resin composition containing polyphenylene sulfide (PPS) containing a fibrous reinforcing material. Considering the abrasion resistance, strength and cost required for the resin pulley 11, a resin material containing a phenolic resin is particularly preferable.

It is principal part cross-sectional explanatory drawing of one Embodiment of the injection molding apparatus of this invention. It is sectional explanatory drawing after the injection process of the injection molding apparatus shown by FIG. It is sectional explanatory drawing in the interruption | blocking process of the injection molding apparatus shown by FIG. It is sectional drawing which shows the sprue and runner isolate | separated from the molded product extruded from the metal mold | die by the resin molding method of this invention, and this molded product.

Explanation of symbols

2 Fixed die 3 Movable die 4 Boss die 5 Rolling bearing (annular metal member)
7 Sprue 8 Runner 9 Film gate 10 Cavity 11 Resin pulley (Rotating body)
21 Fixed cavity type (first mold)
33 Movable cavity type (second mold)
41 Shaft part 42 Flange part 70 Gate cutting pin

Claims (3)

A cavity for forming a rotating body having an annular metal member in the center is constituted by a plurality of molds, and a shaft portion on which the annular metal member is fitted and an annular film gate are formed at the axial center portion of the cavity. A boss mold having a flange portion to be held, the annular metal member is held by the shaft portion, and the film metal gate is sandwiched between the flange portion and the mold. Inject molten resin into the cavity from
When the resin injected into the cavity is cured under a predetermined pressure, the rotating body and the runner are separated by moving the flange portion to the runner side and blocking the film gate,
A resin molding method comprising opening the plurality of molds after resin curing.   The resin molding method of Claim 1 which interrupts | blocks the said film gate by the metal mold | die which forms the said film gate between the said flange parts, and the said flange part. An injection molding apparatus for forming a rotating body having an annular metal member at the center,
A first mold having a sprue along the axis and a second mold facing the first mold; and housing the annular metal member and forming a cavity for forming a rotating body Forming molds, and
A shaft portion into which the annular metal member is externally fitted and fitted into a support hole provided in the second mold so that one end side thereof can be inserted and removed along the axis is formed, and an end portion is formed on the other side of the shaft portion And an inner surface is closely attached to one end surface of the annular metal member, and a flange portion that forms an annular film gate between the outer peripheral edge portion of the outer surface and the first mold, and the annular metal A boss mold for holding the member at the axial center of the cavity;
An injection molding comprising: a boss mold moving means for opening and closing the film gate by moving the boss mold along an axis and moving the boss mold toward and away from the first mold. apparatus.

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