JP3000421B2 - Mold equipment for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold apparatus, and more particularly to an injection mold apparatus for injection-molding a resin molded product having an undercut on its outer surface.

[0002]

2. Description of the Related Art Conventionally, in a mold apparatus for injection molding a synthetic resin product, the molded product has an undercut portion (that is, a molded portion which is difficult to be released by ordinary releasing means such as a knockout pin). For example, as shown in FIG. 6, a slide core B or a push-up core B ′ each having a molding surface corresponding to the undercut portion UC is provided separately from the mold body M ′. Core B, B '
Is retracted or raised with respect to the mold body M ′ to release the undercut portion UC of the molded product W, and then the remaining part of the molded product W is released by using appropriate release means (not shown). Thus, the molded article W is taken out from the mold apparatus.

[0003]

However, in the above-described conventional apparatus, the mold is divided into a plurality of relatively large components, and a part (each of the cores B and B ') is made to move in a complicated manner. Because of the necessity, the structure and shape of the mold become very complicated as a whole, which has caused an increase in cost and a decrease in durability of the mold.

[0004] The present invention has been proposed in view of the above,
An object of the present invention is to provide an injection molding die apparatus that can solve the above-described problems of the conventional apparatus.

[0005]

Means for Solving the Problems To achieve the above object, the invention of each claim is directed to an injection molding die apparatus for injection molding a resin molded product having an undercut portion on an outer surface. A holding pin capable of holding a first portion separated from the undercut portion on the molding surface of the mold, and a second portion of the molded product proximate to the undercut portion forcibly from the molding surface of the mold. An extrusion pin capable of being extruded, and a forced deformation means for elastically deforming the molded product so as to release the undercut portion in a mold open state after the injection molding is provided on the mold, and in particular, a claim is provided. The invention of Item 2 is characterized in that, in addition to the above features, a locking portion is provided at the tip of the holding pin so as to protrude above the molding surface of the mold and lock with the molded product. The invention of claim 2 has an undercut in addition to the features of the invention of claim 2. A release pin for extruding a peripheral portion of the locking portion of the molded product after the release of the portion and detaching from the locking portion is provided so as to be able to protrude and retract from the molding surface of the mold. According to a fourth aspect of the present invention, in addition to the features of the third aspect of the present invention, an extrusion pin first operates to extrude a molded article in a mold-open state after injection molding, and then the extrusion amount of the extrusion pin exceeds a predetermined value. And a drive device that drives the pins up and down so that the release pins and the release pins can also be pushed out.

[0006]

[Operation] In the mold open state after injection molding,
While the first portion separated from the undercut portion is held on the molding surface of the mold by the holding pin, the second portion of the same molded product close to the undercut portion is forcibly pushed from the molding surface of the mold by the extrusion pin. If the mold is extruded, the molded product can be forcibly elastically deformed so as to release the undercut portion of the molded product. It is not necessary to use a split mold, and the structure and the shape of the mold can be simplified accordingly.

According to the second aspect of the present invention, the molded product is formed at the same time as the injection molding by performing the injection molding with the locking portion at the tip of the holding pin protruding above the molding surface of the mold. , The tip of the holding pin can be automatically locked.

[0008] Further, according to the third aspect of the present invention,
After the release of the undercut portion based on the extrusion operation of the extrusion pin, the molded product is automatically released from the locking portion at the tip of the holding pin by operating the release pin while keeping the holding pin fixed to the mold. be able to.

Further, according to the above configuration of the present invention, in the mold opened state after the injection molding, the extrusion pin and the release pin can be operated with a predetermined time difference while the holding pin is fixed to the mold. Therefore, the release of the undercut portion and the release of the molded product from the holding pin can be performed sequentially and efficiently, and the molded product is more easily made than the mold by the pushing-up action of the extrusion pin and the release pin on the molded product. Can be taken out.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing the mold opening state immediately after injection molding of an injection molding mold apparatus according to one embodiment of the present invention.
FIG. 3 is an enlarged cross-sectional view taken along the arrow 2 in FIG. 1, FIG. 3 is a cross-sectional view similar to FIG.
Is an enlarged view of a portion indicated by an arrow 4 in FIG. 1, and FIG. 5 is an operation explanatory diagram showing a procedure of releasing an undercut portion (that is, a protrusion described later).

First, in FIG. 1, a mold apparatus M for injection-molding a resin molded product W such as an inner panel of a motorcycle is mounted on a fixed base 1 having a tie bar 1a extending in a horizontal direction via a mounting plate 20. A fixed die 3 to be fixed and a mounting base 2 on a movable base S slidably guided by the tie bar 1a.
And a movable mold 2 fixed through the movable base 1. The movable base S is fixed to the fixed base 1 by driving means (not shown).
Can be driven forward and backward along the tie bar 1a. The movable mold 2 can be moved forward and backward with respect to the fixed mold 3 as the movable base S moves forward and backward. In the closest approach state, the mold apparatus M is in the mold closed state. It is in a predetermined mold opening state in which the mold can be easily taken out.

In the illustrated example, the molded product W is formed in a bowl shape whose central portion is convexly curved to one side, and the outer surface of the outer peripheral portion has a plurality of portions substantially perpendicular to the surface (in FIG. 2
(Only one is shown) are integrally protruded outwardly at intervals in the circumferential direction. These projections UC are obliquely inclined with respect to the moving direction a of the movable mold 2,
It is difficult to release the mold simply by pushing up along the moving direction a with a normal release knockout pin in the mold opened state after molding, and there is a possibility that the projection UC may be broken if it is forcibly pushed up. is there. Thus, these projections UC constitute the undercut of the present invention.

The movable mold 2 constitutes the mold of the present invention, and includes a base mold 2a fixed on the mounting plate 21.
And a front mold 2b fixed on the base mold 2a and defining a space 4 between the base mold 2a and the mounting plate 21. The front mold 2b is provided on a surface of the front mold 2b facing the fixed mold 3. a first molding surface C ₁ corresponding to the outer surface of the molded product W (i.e. convex) shape is formed.

On the other hand, a second molding surface C ₂ corresponding to the inner surface (ie, concave surface) of the molded product W is formed on the surface of the fixed mold 3 facing the movable mold 2. Thus, in the closed state of the mold apparatus M, a flat cavity C corresponding to the molded product W is defined by the first and second molding surfaces C ₁ and C ₂ , and is fixed in the cavity C. Nozzle N provided on mold 3
The molded product W is integrally molded by injecting the synthetic resin in a molten state at a high pressure through the process.

The movable mold 2 is provided with forced deformation means A for elastically deforming the molded product W so that each projection UC of the molded product W is released from the mold after the injection molding. The forced deforming means A is configured to move the central portion 6c of the molded product W as a first portion separated from each projection UC as a first molding surface C _1.
Holding pin P ₁ that can be fixedly held on
Of, and includes at least a plurality of extrusion pins P ₂ to the outer peripheral portion close 6a obtain forcibly extruded from the second molding surface C ₂ of the second portion close to the protrusions UC.

The holding pin P ₁ penetrates through the mounting plate 21 and protrudes from the surface thereof, and is provided with a set screw 22 screwed into a mounting hole of the mounting plate 21.
It is detachably fixed to. The distal end portion of the holding pin P _1, with the locking portion 7 is integrally have always projected on the first molding surface C ₁ of the movable die 2 can be halted automatically engages the molded product W with the injection molding Has been established.

As shown in FIG. 2, the locking portion 7 is formed by integrating a spherical tip portion 7b at the upper end of a tapered base portion 7a tapered upward as shown in FIG. The portion is not limited to such a shape, and for example, as shown in FIG. 3, an inverted tapered tip portion 7b 'may be integrated with the tapered base portion 7a. That engagement portion 7 is easily lockable in articles W by injection molding, it is suitably selected readily removable shape than moldings W and with a extrusion operation of withdrawal pins P ₃ to be described later. The shape shown in FIG. 2 is effective when the thickness T of the molded product W is relatively large, and the shape shown in FIG. 3 is effective when the thickness t of the molded product W is relatively small. (Ie, t <T).

[0018] The ejector pin P ₂ are provided the same number as the protruding portions UC, the protrusions U around the holding pin P ₁
C, and the intermediate portion thereof penetrates the space 4 in the movable mold 2. The distal end surface of the ejector pin P ₂ is obliquely cut so that the first molding surface C ₁ flush, also enormous head provided at the proximal end of each ejector pin P ₂ is the mounting plate 21 above Extruded plate 8 whose back surface is in contact with
a and the second extruded plate 8b which is polymerized and fixed thereto. The first and second extruded plates 8a, 8
“b” constitutes the extrusion plate 8, and each extrusion pin P ₂ together with the extrusion plate 8 can integrally move forward and backward.

A knockout cylinder Cy is mounted on the movable base S. A plurality of knockout pins P which can be driven by the cylinder Cy to advance and retreat toward the fixed mold 3 side.
Has abutment with the push-out plate 8 (that is, the rear surface of the first push-out plate 8a) through the movable base S and the mounting plate 21. Therefore it is possible to advance and retract drive each ejector pin P ₂ through the knockout pin P and an extrusion plate 8 by the operation of the cylinder Cy on the fixed die 3 side.

[0020] Most of the tip portion of the holding pin P ₁ is surrounded thereto by slidably fitted sleeve-like withdrawal pin P ₃ were. The release pin P ₃ is used to push out the peripheral portion of the locking portion 7, that is, the central portion 6 c of the molded product W after the release of each projection UC, and to forcibly release the molded product W from the locking portion 7. Provided. The distal end surface of the withdrawal pin P ₃ are abutting to form a part of the first molding surface C ₁ is formed flat, and its proximal end extends through an extrusion plate 8 to the attachment plate 21 .

[0021] The proximal end of the withdrawal pin P ₃ is formed in a larger diameter than its front portion side, adapted to engage with the step portion of the through hole of the stepped bored in the first pushing plate 8a It has become.
The shape of the withdrawal pin P ₃ is not limited to the illustrated example, especially when the retaining pin P ₁ as in the illustrated example is formed in a sleeve shape surrounding concentrically the said leaving pin P ₃ of the ring The peripheral portion of the molded product W (that is, the central portion 6c) of the molded product W can be projected substantially uniformly over the entire circumference by the tip end surface, so that the molded product W cannot be detached from the locked portion 7. It can be performed accurately without.

Furthermore the withdrawal pin P _3, the intermediate portion outer periphery that passes through the space portion 4, the extrusion plate 8 mounting plate 21 (leaving the pin P ₃ having a base end to thus the plate 21 abuts against) the place to An engagement ring 10 that engages with the pushing plate 8 (that is, the second pushing plate 8b) when moving forward by a fixed amount is fitted and fixed. The subsequent it Thus to the forward course of the extrusion plate 8 engaged with the engaging ring 10, in conjunction disengagement pin P ₃ on the basis of its engagement in the extrusion plate 8 (i.e. ejector pin P ₂₎ It is possible to integrally follow and advance.

As shown in FIG. 4, a horizontal hole 10a is formed in the peripheral wall of the engagement ring 10, and the inner end of the screw 9 is detached by tightening a small screw 9 screwed into the horizontal hole 10a. it can be pressed against the outer circumferential surface of the pin P _3, thereby, (that is, the position adjustable) to any position leaving the pin P ₃ the engagement ring 10 can be fixed. Instead of such a structure may be permanently affixed by welding or the like engaging ring 10 to the disengaged pin P _3.

Thus, the engagement ring 10 and the push-out plate 8 are disengaged when the push-out pin P ₂ advances by a predetermined amount.
₃ in conjunction with the extruding pin P ₂ to constitute an interlocking mechanism I for follow advanced, also constitutes a driving device D of the present invention and the knockout cylinder Cy with the interlocking mechanism I in cooperation with each other .

The pushing pin P ₂ and the releasing pin P ₃
Can be constituted by a plurality of actuators which can individually drive the drive device D independently. In particular, as shown in the illustrated example, the drive device D is connected to the interlocking mechanism I and the cylinder Cy.
Costs when configured, because it is possible to operate the ejector pin P ₂ and leaving the pin P ₃ with a certain time difference by a common actuator (i.e. cylinder Cy), the structure simplification of the drive unit D, and hence in the It can contribute to savings.

Next, a procedure for taking out the resin molded article W injection-molded by the mold apparatus M from the movable mold 2 after opening the mold will be described with reference to FIGS. FIG. 1 shows a state immediately after the mold apparatus M is opened after injection molding, that is, a state in which the movable mold 2 is retracted to a predetermined retreat limit.

From this state, the knockout cylinder C
By actuating y, the push-out plate 8 is driven forward through the knockout pin P toward the fixed mold 3, so that each push-out pin P ₂ integral with the plate 8 is also driven forward, so that each of the protrusions UC of the molded product W the proximate outer peripheral portion close 6a extruded from the first mold surface C _1, but because such also held in a state under pins P ₁ and leaving the pin P ₃ is still stationary, the molded article W, the protrusions UC
The retaining pin P ₁ more spaced central portion 6c can be fixedly held in the first mold surface C _1. This allows
As shown in FIG. 5 (a), the molded product W is swung so that the central portion 6c in the fixed state is a swing fulcrum, and a portion 6a close to the outer periphery near each projection Uc is pushed up and narrows inward. Elastic deformation occurs, and the direction of movement of each projection UC due to this deformation is substantially in the direction of the opening of the molding recess 12 corresponding to each projection UC on the first molding surface C _1. Each projection UC can easily come out of the recess 12, and thus the release of each projection UC can be performed smoothly. Since the molded product W has elasticity, there is no fear that the central portion 6c is broken by the elastic deformation.

When the outer surface of the push-out plate 8 is engaged with the engagement ring 10 on the outer periphery of the release pin P ₃ by the continuous advance of the push-out plate 8, the release pin P ₃ is thereafter moved.
(I.e., the push pin P ₂ ) moves forward integrally with the advance. According to the extrusion operation of the disengagement pin P _3, molding for pushing up the molded article is W, the holding pins P ₁ tip around, from the holding pin P ₁ end of the engagement portion 7 as shown in FIG. 5 (b) The article W can be automatically removed.

[0029] After this withdrawal, the molded product W is restored spontaneously by its own elastic force, the central portion 6c is lifted from leaving the pin P _3, the outer peripheral portion close 6a is in close contact supported on the extrusion pin P ₂ Move forward. And allowed to separate from the extrusion pin P ₂ by its own weight or as a suitable means molded articles W at the forward limit of the ejector pin P ₂ as shown in FIG. 5 (c) to take out to the outside.

[0030] The central portion 6c outer surface of the thus retrieved moldings W, forcing the molded product W from the holding pin P ₁ end of the engagement portion 7 as evidenced in FIG. 5 (b) Traces of disengagement occur. However, the cavity C of the locking portion 7 is so positioned that such a trace is located on the back side of the molded product W.
If the projecting position to the inside is set, there is no fear that the trace is conspicuous in appearance when the molded article W is used, and no practical inconvenience occurs.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various embodiments are possible within the scope of the present invention. For example, molded product W
Is not limited to the shape of the illustrated example, but can be applied to molded products with various shapes of undercut portions.
It may be in the shape of a channel in the shape of a letter, or in the shape of a refraction plate with at least one fold in the middle.

[0032]

As described above, according to the invention of each claim,
In a state in which the mold is opened after the injection molding, the first part of the molded product, which is separated from the undercut portion, is held on the molding surface of the mold by the holding pin, and the second portion of the molded product close to the undercut portion is held. By forcibly extruding the part from the molding surface of the mold with an extrusion pin, the molded product can be elastically deformed and the undercut part of the molded product can be released easily, so the mold release of the undercut part Therefore, the mold does not need to be a complicated divided mold, so that the structure and the shape of the mold can be simplified, which contributes to cost reduction and durability improvement of the mold. .

According to the second aspect of the present invention, the retaining pin is formed by injection-molding the retaining pin at the tip of the retaining pin so as to protrude above the molding surface of the mold. Since the tip can be locked automatically,
That makes the handling of the holding pins simpler.

Further, according to the third aspect of the present invention, after the release of the undercut portion based on the pushing operation of the pushing pin, the detaching pin is pushed out while the holding pin is fixed to the mold, so that the tip of the holding pin is moved. The molded product can be automatically detached from the locking portion of the, so that the work of engaging and disengaging the holding pin with respect to the molded product can be fully automated, which can contribute to an improvement in work efficiency.

According to the fourth aspect of the present invention, in the mold opened state after the injection molding, the push-out pin and the release pin can be operated with a fixed time difference while the holding pin is fixed to the mold. Release of the cut part and release of the molded product from the holding pin can be performed sequentially and efficiently,
In addition, the molded product can be easily taken out of the mold by the extruding action of the extrusion pin and the release pin on the molded product, which can contribute to further improvement of work efficiency.

[Brief description of the drawings]

FIG. 1 is a plan view showing a mold opening state after injection molding of a mold apparatus according to one embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the arrow 2 in FIG.

FIG. 3 is a cross-sectional view similar to FIG. 2, showing a modified example of a locking portion at the tip of a holding pin.

FIG. 4 is an enlarged view of a portion indicated by an arrow 4 in FIG. 1;

FIG. 5 is an operation explanatory view showing a procedure for releasing the undercut portion.

FIG. 6 is a longitudinal sectional view showing an outline of a conventional mold apparatus.

[Explanation of symbols]

A Forced deformation means C _{1 First} molding surface as molding surface D Driving device M Mold device P ₁ Holding pin P ₂ Push-out pin P ₃ Release pin UC Projection as undercut part W Molded product 2 Movable as mold Mold 6a Outer perimeter part as second part 6c Central part as first part 7 Locking part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-155710 (JP, A) JP-A-55-114541 (JP, A) JP-A-5-200806 (JP, A) JP-A-5-2008 69461 (JP, A) Japanese Utility Model Hei 2-9520 (JP, U) Japanese Utility Model Sho 59-68922 (JP, U) Japanese Utility Model Utility Model 59-157804 (JP, U) Japanese Utility Model Utility Model 50-72759 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/26-45/44 B29C 33/44

Claims (4)

(57) [Claims] An injection molding die apparatus for injection-molding a resin molded product (W) having an undercut portion (UC) on an outer surface, wherein the molded product (W) is separated from the undercut portion (UC). A holding pin (P ₁ ) capable of holding the first portion (6c) thus formed on the molding surface (C ₁ ) of the mold (2) and an undercut portion (UC) of the same molded product (W). An extrusion pin (P ₂ ) capable of forcibly extruding the second portion (6a) from the molding surface (C ₁ ) of the mold (2); A mold device for injection molding, wherein a forced deformation means (A) for elastically deforming a molded product (W) so as to release the UC) is provided in the mold (2). The distal end of 2. A retaining pin (P _1), the molding surface (C ₁₎ locking portion can be locked to project the molded article (W) onto the mold (2) to (7) The mold apparatus for injection molding according to claim 1, wherein the mold apparatus is provided. 3. A release pin for extruding a peripheral portion of the locking portion (7) of the molded product (W) after releasing the undercut portion (UC) and releasing the molded product (W) from the locking portion (7). the (P _3), characterized in that provided retractably from the molding surface of the mold (2) (C _1), an injection molding die apparatus according to claim 2. 4. A molded product (W) in a mold opened state after injection molding.
On the other hand, first, the push-out pins (P ₂ ) are pushed out, and when the push-out amount of the push-out pins (P ₂ ) exceeds a predetermined value, the release pins (P ₃ ) are also pushed out so that the push-out pins (P ₂ , P ₂ ) are pushed out. The injection molding die device according to claim 3, further comprising a driving device (D) for driving the P ₃ ) up and down.