JPH0839606A - Insert molding method and metallic mold apparatus therefor - Google Patents

Abstract

PURPOSE:To achieve the miniaturization and wt. reduction of a metallic mold apparatus and a molding machine by reducing the vol. and wt. of a mold by utilizing the pressure of a molding resin. CONSTITUTION:Ejector plates 14, 15, 24, 25 are respectively attached to a fixed core 1 and a movable core 2 in a freely slidable manner and pressure receiving pins 17, 27 and insert support pins 18, 28 are fixed thereto. Coned disc springs 16, 26 are attached to the ejector plates to be energized toward a cavity. When the resin pressure in a runner is increased, the pressure receiving pins 17, 27 receiving pressure by the pressure receiving surfaces facing to the runner of them retreat along with the ejector plates to allow the insert support pins to retreat from the cavity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insert molding die apparatus and an insert molding method, and more particularly, to an insert member supported by a movable supporting member in a cavity to fill a molding fluid, and then the movable supporting member is inserted into the cavity. The present invention relates to a molding technique configured to retreat from the inside and supplement the molding fluid.

[0002]

2. Description of the Related Art Conventionally, for example, when a golf ball, a mouse ball or the like is formed by resin molding, a spherical body as an insert member is housed inside a spherical cavity and the periphery of the spherical body is covered with resin. There is a need. In this case, first, the molding resin is filled in a state where the spherical body is supported by the support pin in the center of the cavity, and when the pressure in the cavity becomes almost uniform due to the completion of filling, the support pin is retracted from the cavity. By adding a molding resin, the circumference of the sphere is completely filled with the resin.
Here, the support pin is fixed to an ejector plate, and the ejector plate is driven by a hydraulic cylinder.

[0003]

However, in the above-mentioned conventional insert molding method, since the cross-sectional area of the mold and the thickness of the mold are increased due to the hydraulic cylinder to be installed, it is usual to compare the size of the molded product. There is a problem that a larger molding machine is required, and since the weight of the mold also increases, the handleability in mold replacement and the like deteriorates, and the manufacturing cost of the mold also increases, and as a whole Manufacturing cost increases. Further, it is difficult to control the hydraulic pin when the support pin is retracted. For example, it is necessary to set the evacuation timing by detecting the resin pressure in the cavity with a sensor or measuring it with a timer from the injection start time of the molding machine, but the absolute pressure value and time differ depending on the molding conditions. Since it is difficult to secure the detection accuracy of, it takes a long time to adjust. Therefore, the present invention is to solve the above problems, and an object thereof is to realize a method or a mold apparatus in which the mold volume and weight are reduced while having the same function in the insert molding method or the mold apparatus. By doing so, the manufacturing cost can be reduced.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the means taken by the present invention is to position an insert member by means of a movable support member which is mounted in the cavity so that it can be retracted and retracted, and the molding fluid is placed in the cavity. After filling
In an insert-molding die device configured to retreat the movable support member from the inside of the cavity to fill the molding fluid, a pressure receiving portion that receives the pressure of the molding fluid introduced into the cavity, When the pressure of the pressure receiving portion is less than or equal to a predetermined value, the movable supporting member is urged in a direction to project into the cavity, and when the pressure of the pressure receiving portion exceeds a predetermined value, the movable supporting member is moved into the cavity. And an elastic member arranged so as to be retracted from.

In this case, it is preferable that the pressure receiving portion is provided with a pressure receiving surface facing the flow path of the molding fluid supplied into the cavity.

Further, it is preferable that the pressure receiving portion is provided with a pressure receiving surface which is formed at a tip end portion of the movable supporting member and does not come into contact with the insert member.

Further, the movable support member and the pressure receiving portion are respectively arranged in a pair of mold portions which are opened and closed,
It is preferable that the elastic members are connected to ejector plates respectively provided on the pair of mold parts, and the elastic members urge the ejector plates toward the cavity.

In this case, it is desirable that the ejector plate be slidably mounted in the mold via a bearing.

Further, the elastic constant of the elastic member for urging the ejector plate provided on the one die part is smaller than the elastic constant of the elastic member for urging the ejector plate on the other die part. It is desirable to set the elastic constant small.

Next, as the insert molding method, the step of positioning the insert member in the cavity of the mold by the movable support member biased by the elastic member, and the step of filling the cavity with the molding fluid, By raising to a first pressure value higher than the pressure required to fill the resin in the cavity, and withdrawing the movable support member from the cavity against the elastic force of the elastic member by the pressure. The step of supplementing the molding fluid for the retracted portion of the movable support member and switching to the second pressure lower than the first pressure and set to a pressure range within which the movable support member does not return to the inside of the cavity. The step of holding for a predetermined time is sequentially executed.

[0011]

According to the first aspect of the present invention, the movable support member is operated against the elastic force of the elastic member by the pressure of the molding fluid applied to the pressure receiving portion, thereby eliminating the need for other driving means. As a result, the volume and weight of the driving portion can be reduced, so that the mold can be made smaller, lighter and less expensive.

According to the second aspect, since the pressure receiving surface faces the flow path of the molding resin, a stable and reliable driving force can be obtained regardless of the shape of the cavity.

According to the third aspect, since the pressure receiving surface is formed at the tip of the movable supporting member, it is not necessary to form another pressure receiving portion and the structure is simple.

According to the fourth aspect, the insert member is clamped and supported between the movable supporting members respectively arranged in the pair of mold parts based on the elastic force of the elastic member for urging the ejector plate. Therefore, the insert member can be stably supported.

According to the fifth aspect, since the ejector plate can be slid smoothly by the bearing,
The movable support member can be reliably operated, and wear of the sliding portion can be prevented.

According to the sixth aspect, when the molded product is opened and the molded product is taken out, the molded product is surely left on the side of the mold part equipped with the elastic member having a small elastic constant. The take-out operation can be easily performed.

According to the seventh aspect, insert molding can be performed at a low cost by using the small and lightweight mold as described above without degrading the quality of the molded product.

[0018]

EXAMPLES Examples of the insert molding die apparatus or molding method according to the present invention will be described below. 1 and 2
Shows the configuration of the main part of the first embodiment according to the present invention. This embodiment is a molding die attached to a vertical molding machine, in which a fixed core 1 shown in FIG. 1 is housed inside a fixed mold plate, and a movable core 2 is inside a movable mold plate. It is housed. The fixed core 1 is fixed to the molding machine main body via the fixed mold plate, and the movable core 2 is attached to the fixed core 1 below the fixed mold plate via the movable mold plate so as to be movable up and down. ing.

The fixed core 1 is provided with a runner groove 11, a gate groove 12 and a cavity recess 13 which are connected to the molten resin supply port. In addition, as shown in FIG.
The movable core 2 is provided with a runner groove 21, a gate groove 22 and a cavity recess 23 corresponding to the fixed core 1. Ejector plates 14 and 15 fixed to each other are housed inside the fixed core 1 so as to be movable in a direction perpendicular to the parting surface PL. Ejector plates 2 fixed to each other inside the movable core 2
4, 25 are housed movably in a direction perpendicular to the parting surface PL. Ejector plates 14, 2
4, annular grooves 14a and 24a are formed, and the annular groove 1
Disc springs 16 and 26 are introduced into 4a and 24a.

Each of the ejector plates 15 and 25 has four
The pressure receiving pins 17 and 27 of each book are fitted and held between the ejector plates 14 and 24. The tip surfaces of the pressure receiving pins 17 and 27 are pressure receiving surfaces 17a and 27a and face the insides of the runner grooves 11 and 21. Three insert support pins 18 and 28 are fitted to the ejector plates 15 and 25, respectively.
4 and 24 are held. Ends of the insert support pins 18 and 28 face the insides of the cavity recesses 13 and 23, and spherical support surfaces 18a and 28a for supporting the spherical body 3 as an insert are formed at the tips thereof.

A pair of return pins 29 are fixed to the ejector plates 24 and 25, respectively.
The tip surface of 9 is in contact with the parting surface PL of the fixed core 1. The return pin 29 is for returning the ejector plates 24 and 25 to a predetermined fixed position when the mold is clamped. A protruding rod 31 is attached to the main body of the molding machine, and the ejector plates 24 and 25 are projected from the movable side to take out the molded product.

Next, the method of use, operation and action of the above embodiment will be described. First, a mold containing the core is set in a vertical molding machine, and the movable side mold plate is opened to bring the mold into an opened state. In this state, the sphere 3 is placed on the support surface of the insert support pin 28 protruding from the cavity recess 23 on the movable side. Here, the support surface of each insert support pin 28 is formed in a shape capable of forming the outer peripheral shape of the molded product or the same shape as the outer peripheral shape of the insert member (sphere 3).
Next, when the mold is closed, the cavity is completed by abutting the cavity recesses 13 and 23, and at the same time, the spherical body 3 also abuts on the supporting surface of the insert support pin 18 on the fixed side. It is clamped by the insert support pins 18 and 28 in the cavity by the elastic force and is fixed at a substantially central position.

The molten resin injected from the injection cylinder (not shown) of the main body of the molding machine passes through the spool, runner and gate and flows into the cavity (time t1). When the cavity is filled with the resin, the pressure in the cavity rises to a predetermined holding pressure value P1 (time t2) as shown in FIG. 3, and the pressure is held there to become the primary holding state ( Times t2 to t3). Here, when the pressure in the cavity rises to the holding pressure value P1, the four pressure receiving pins 17, 27 having pressure receiving surfaces facing the runner grooves 11, 21 cause the ejector plates 14, 15 and 24, 25 to move to the disc springs 16, 26
It is moved in a direction away from the parting surface PL against the elastic force of.

The ejector plates 14, 15 and 24,
When 25 moves, the insert support pins 18 and 28 retreat from the inside of the cavity. At this time, even if the insert support pins 18 and 28 are retracted, since the inside of the cavity is almost filled with the resin, the internal pressure is balanced, and the spherical body 3 is held at the center position of the cavity with almost no movement. . In this state, molten resin is further introduced into the cavity, and the sphere 3 is completely covered with the resin layer. Insert support pin 1
Since the supporting surfaces 8 and 28 are set to retract to the position where the outer shape of the product is formed at the maximum retracted position of the ejector plates 14, 15 and 24 and 25 (the position where the ejector plate contacts the template), The product is formed by cooling the resin as it is.

After the primary pressure holding state continues for a preset time, the resin pressure in the cavity is reduced to the secondary pressure holding state. After this secondary pressure holding state is maintained for a predetermined time, the resin pressure is released. After the resin in the mold is cooled and solidified, the mold is opened to open the movable side mold plate, and the molded product remains on the movable side core 2. The projecting rod 31 of the molding machine advances, pushes out the movable ejector plate, and the pressure receiving pin 27 and the insert support pin 28 project the molded product.

In the above embodiment, the disc springs 16 and 26 are
There is a problem in the relationship between the elastic force caused by the pressure and the resin pressure that pushes out the pressure receiving pins 17 and 27 at the runner portion. As shown in FIG. 3, the setting range A of the pressure value corresponding to the elastic force of the disc springs 16 and 26 is the insert support pin 1 in the secondary pressure holding state.
It is necessary to set the secondary holding pressure value P2 or less so as not to return 8 and 28 to the inside of the cavity, and to prevent the insert support pins 18 and 28 from operating reliably from the maximum filling pressure range B of the molten resin. Also needs to be set low. Further, the set range A needs to be larger than the minimum pressure range C required to fill the molten resin in the cavity. Here, the driving force received by the pressure receiving pins 17 and 27 from the resin pressure is equal to the resin filling pressure multiplied by the area of the four pressure receiving surfaces in the present embodiment, and this is the elastic force of the disc springs 16 and 26. Depending on the size relationship, insert support pin 18,
28 actions are determined.

The pressure holding value P1 is set to the insert support pins 18, 28 by applying sufficient initial power to the pressure receiving pins 17, 27.
Is set to a value sufficiently higher than the setting range A in order to reliably operate. Insert support pin 18,
After the operation of 28 to complete the filling of the molten resin, the holding pressure within the pressure range in which the insert support pins 18 and 28 do not return to the inside of the cavity in order to prevent overpacking and release the internal residual stress of the molded product. The pressure is reduced to P2. The holding pressure value P2 is released after a lapse of a predetermined time in which the resin in the cavity is cooled to some extent, and then the mold is opened when the molded product is solidified.

In this embodiment, the newly formed runner 2 is used.
Since the four pressure receiving pins 17 and 27 facing 1'are attached, it is possible to reduce the direction deviation of the driving force due to the resin pressure and to increase the operation sensitivity of the insert support pin with respect to the change of the resin pressure. Therefore, the ejector plate can be operated reliably and smoothly. Here, the pressure receiving surface of the pressure receiving pin is a portion other than the runner, for example,
It is also possible to provide it on a spool or a gate.

Next, a second embodiment according to the present invention will be described with reference to FIGS. In this embodiment, the pressure receiving pin attached in the first embodiment is not used, but instead, the support surfaces 38a and 48a formed at the tips of the insert support pins 38 and 48 have a diameter that matches the inner surface shape of the cavity. It is formed on the spherical surface of. This support surface 38a, 48
The center of the a is in contact with the surface of the sphere 3 at its central portion, and supports the sphere 3 under compression by the elastic force of the disc springs 16 and 26. In addition, the peripheral portion thereof is exposed from the surface of the spherical body 3 in the cavity space. Therefore, when the molten resin is filled in the cavity to increase the internal pressure, the supporting surface 38
Resin pressure is applied to the peripheral portions of a and 48a, and stress is generated in the axial direction of the insert support pins 38 and 48. This stress causes the ejector plates 14, 15, 24, 25 to retract, and the insert support pins 38, 48 to retract from the cavity.

In the second embodiment, since the insert support pin itself directly receives the resin pressure, the pressure receiving pin is unnecessary, and the same effect as that of the first embodiment can be obtained at a low cost by a structurally simple structure. it can. In the first embodiment described above, the driving force of the ejector plate is secured by providing four pressure receiving pins, and the ejector plate receives the driving force obliquely to increase the sliding resistance, resulting in malfunction. Increased wear between the outer peripheral surface of the ejector plate and the inner peripheral surface of the core block is avoided. But actually,
There may be a difference in the amount of movement between the four pressure receiving pins,
There is a risk of malfunction and wear. However, in this embodiment, the resin pressure is applied to the insert support pin itself, and the support surfaces 38a and 48a are concave curved surfaces symmetrical with respect to the center portion. A driving force is generated in the axial direction to ensure reliable operation.

In this embodiment, the driving force increases as the support surface of the insert support pin deviates from the spherical surface, while the outer shape of the molded product is formed in a shape deviated from the sphere when the insert support pin retracts. Therefore, when the surface shape of the insert member and the surface shape of the molded product are the same, it is necessary to appropriately design in consideration of the elastic force of the disc spring and the pressure receiving amount of the supporting surface. In the first embodiment, the support surface formed at the tip of the insert support pin is
It is sufficient that it can support the sphere 3 that is an insert member, and it does not have to be a spherical surface that matches the sphere 3. Therefore, usually, the shape of the support surface is formed so as to match the shape of the outer surface of the molded product with the insert support pin retracted.

Next, a third embodiment according to the present invention will be described with reference to FIG. This embodiment has substantially the same structure as that of the first embodiment, but a bearing (ball) is provided between the fixed core 1 and the ejector plates 14 and 15 and between the movable core 2 and the ejector plates 24 and 25. Cage) 3
9, 49 are provided. This bearing 39,4
9 makes the operation of the ejector plate smooth and improves the operation accuracy of the insert support pin. It should be noted that this bearing has the same effect even if it is adopted in the second embodiment.

Further, in this embodiment, similarly to the first embodiment, the disc spring 1 is placed in the annular grooves of the ejector plates 14 and 24.
6 and 26 'are accommodated, the movable side mold plate and the ejector plate 24 are different from the elastic constant (spring constant) of the disc spring 16 elastically provided between the fixed side mold plate and the ejector plates 14 and 15. , 25 is set to a small elastic constant of the disc spring 26 'elastically mounted between the disk spring 26' and the disc spring 25 '. With this configuration, when the mold plate is opened to take out the molded product, the molded product is reliably separated from the fixed core 1 by the elasticity of the disc spring 16 while being pressed against the movable core 2. Eliminates mistakes in taking out molded products. In this way, when performing mold opening while holding the molded product in one mold part,
Although it may be set to be left on either the fixed side or the movable side, it is usually configured to be left on the movable side provided with a protrusion mechanism.

Although the disc spring is used as the elastic member in each of the embodiments described above, it is obvious that other known elastic members such as a coil spring, a leaf spring, and an elastic plate can be used. Further, the molded product is not limited to the case where the spherical body is used as the insert member as described above, but can be applied to insert members having various shapes. In this case, it is not necessary for the molded product to completely enclose the periphery of the insert member with resin, and any molded product can be used as long as it uses the molding device that supports the insert member with the movable support member in the cavity as described above. Can also be applied to.

Finally, a fourth embodiment of the present invention will be described with reference to FIGS. 7 to 9. This embodiment has almost the same configuration as the first embodiment, and the substantially same parts are denoted by the same reference numerals and the description thereof will be omitted. In this mold, the runner and the gate are not formed in the fixed core 1, but the runners 51 and 52 and the gate 56 are formed only in the movable core 2.
Further, the ejector plate 55 slidably accommodated in the movable side core 2 is further forward in a state where the insert support pin 28 supports the sphere 3 which is an insert member,
That is, the insert support pin 28 is formed so as not to move in the protruding direction. In this embodiment, gas release pins 53 and 61 are provided for discharging the gas generated or staying in the cavity from the gap around the pin.

As shown in FIGS. 8 and 9, three insert support pins 18 and 28 are formed in the central portion between the insert support pins 18 and 28, as shown in FIG.
As shown in FIG.
61a is arranged so as to be substantially continuous with the surfaces of the cavities 13 and 23. The degassing pins 53 and 61 are slidably inserted with play in the small holes formed in the ejector plates 24, 25, 14 and 15, respectively.
Expanded portions 53b and 61b are provided at the rear end.
The enlarged diameter portions 53b and 61b and the ejector plate 24,
Coil springs 54 and 62 are housed between the coil springs 14 and 14. Here, the expanded diameter portion 53b is in contact with the protruding rod 31 and the expanded diameter portion 61b is in contact with the template on the fixed side.

Usually, the degassing pins 53 and 61 are fixed to the ejector plates 24, 55, 14 and 15, and are formed so as to project into the cavity similarly to the insert support pins 28 and 18 and to project and retract similarly. Alternatively, the insert support pin itself may also be used as a gas vent hole. However, since the insert support pin and the degassing pin attached at different positions have different forming positions with respect to the cavity, the tip surfaces 53a, 61
Since the protrusion amount of a in the cavity is different from the protrusion amount of the support surfaces 18a and 28a, the insert support pins 18 and 28
When the support surfaces 18a and 28a are moved back to match the surfaces of the cavities, the tip surfaces of the gas vent pins 53 and 61 retreat too much, and the surface of the molded product becomes convex at the mounting position of the gas vent pins 53 and 61. The problem of being formed arises.

Therefore, in the present embodiment, the gas vent pin 5
3, 61 are attached to the ejector plates 24, 25, 14 and 15 so as to move freely while being constantly biased to the side opposite to the cavity via coil springs 54 and 62. As a result, the enlarged diameter portion 53b of the gas vent pin 53 normally projects and abuts on the rod 31, and the tip surfaces 53a and 61a are maintained in a state of substantially matching the surface of the cavity. However, at the end of molding, the projecting rod 31 of the molding machine advances to push out the expanded diameter portion 53b together with the ejector plate on the movable side, and the gas release pin 53 projects the molded product together with the pressure receiving pin 27 and the insert support pin 28. . Here, the molded product can be released from the mold only based on the elastic force of the movable side disc spring 26, but if the molded product has a large bite with respect to the mold, the operation of the protruding rod 31 is required.

In this embodiment, three return pins 19 and 29 are provided. Here, by making the lengths of the return pins 19 and 29 slightly project from the parting surface PL, even if the diameter of the ball 3, which is an insert member, varies, the insert support pin 1
It is possible to prevent the balls 8 and 28 from abutting against the ball 3, and to avoid abrasion of the support surface of the insert support pin.

[0040]

As described above, according to the present invention, the movable support member is operated against the elastic force of the elastic member by the pressure applied to the pressure receiving portion, and the driving means using other power is used. Is unnecessary, and the volume and weight of the drive part can be reduced, so the mold can be made smaller, lighter, and less expensive, and the overall equipment including the molding machine can be made smaller. It is possible to reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a mold structure of a first embodiment according to the present invention.

FIG. 2 is an arrow view showing a state of being cut along the line II-II in FIG.

FIG. 3 is a graph showing the pressure in the cavity during insert molding according to the present invention.

FIG. 4 is a sectional view showing a mold structure of a second embodiment according to the present invention.

5 is an arrow view showing a state of being cut along the line VV in FIG. 1. FIG.

FIG. 6 is a sectional view showing a mold structure of a third embodiment according to the present invention.

FIG. 7 is a sectional view showing a mold structure of a fourth embodiment according to the present invention.

8 is an arrow view showing a state of cutting along the line VIII-VIII in FIG. 7. FIG.

9 is an arrow view showing a state of cutting along line IX-IX in FIG. 7. FIG.

[Explanation of symbols]

 1 Fixed side core 2 Movable side core 3 Sphere 14, 15, 24, 25, 55 Ejector plate 16, 26, 26 'Disc spring 17, 27 Pressure receiving pin 17a, 27a Pressure receiving surface 18, 28, 38, 48 Insert support pin 18a , 28a, 38a, 48a Supporting surface 39, 49 Bearing

Claims (7)

[Claims] 1. The molding fluid is positioned by inserting a molding fluid into the cavity by a movable support member that is mounted in the cavity so as to be retractable, and then retracts the movable support member from the cavity. In a mold device for insert molding configured to compensate for the pressure, a pressure receiving portion that receives the pressure of the molding fluid introduced into the cavity, and the movable portion when the pressure of the pressure receiving portion is below a predetermined value. When the pressure of the pressure receiving portion exceeds a predetermined value by urging the supporting member in the direction of protruding into the cavity,
An insert molding die apparatus, comprising: an elastic member arranged to retract the movable support member from the cavity. 2. The insert molding die apparatus according to claim 1, wherein the pressure receiving portion has a pressure receiving surface facing a flow path of a molding fluid supplied into the cavity. 3. The insert molding die device according to claim 1, wherein the pressure receiving portion includes a pressure receiving surface which is formed at a tip end portion of the movable support member and does not come into contact with the insert member. 4. The movable support member and the pressure receiving portion according to claim 1, wherein the movable support member and the pressure receiving portion are respectively provided in a pair of mold portions that are opened and closed, and are connected to ejector plates provided in the pair of mold portions, respectively. The mold device for insert molding, wherein the elastic member urges the ejector plate toward the cavity. 5. The mold apparatus for insert molding according to claim 4, wherein the ejector plate is slidably mounted in the mold via a bearing. 6. The elastic member according to claim 4, wherein the elastic constant of the elastic member that biases the ejector plate provided on the one die part is greater than the elastic constant of the elastic member that is provided on the other die part. The mold device for insert molding, wherein the elastic constant of the elastic member is set to be small. 7. A step of positioning an insert member in a cavity of a mold by a movable support member biased by an elastic member, a step of filling a molding fluid in the cavity, and a step of filling a resin in the cavity. The pressure is raised to a first pressure value higher than that required to withdraw the movable support member from the inside of the cavity against the elastic force of the elastic member due to the pressure, and the retracted portion of the movable support member. The step of supplementing the molding fluid and the step of switching to a second pressure that is lower than the first pressure and set to a pressure range within which the movable support member does not return to the inside of the cavity and hold it for a predetermined time are sequentially performed. An insert molding method, characterized in that the method is performed.