JPH0131460Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention has at least two projecting pieces 1b and 1d projecting outward from the container side wall 1a, as shown in FIG. 5B, for example, and one The projecting piece 1b has a bent part or a folded part 1e forming a certain angle on the side of the other projecting piece 1d, thus creating a so-called undercut part. The present invention relates to a molding die, particularly an undercut molding device.

BACKGROUND ART Conventionally, as an undercut forming apparatus for a container molding die for injection molding a container having an undercut portion as described above, the one described in Japanese Utility Model Application Publication No. 50-99267 is known. This undercut forming device includes a first slide piece that forms the outer surface of the folded portion of the container opening, a second slide piece that forms the inner surface of the folded portion of the side mold of the container, and other protruding pieces. a third slide piece for forming a flange, and a fourth slide piece inserted like a wedge between the first and second slide pieces and the third slide piece; is slid forward and backward by a guide pin (or means such as a hydraulic cylinder or spring), and when it enters, it pushes the second slide piece on the wedge-shaped inclined surface and slides it forward to a predetermined position, and when it leaves, it slides forward as the wedge-shaped inclined surface moves. The piece is configured to slide backward by a spring (or other appropriate means) and escape from the folded portion.

Problems to be Solved by the Present Invention The conventionally known undercut forming apparatus described above is very complex, consisting of a combination of a total of four slide pieces, numbered 1 to 4, and each slide piece is individually slid in a unique direction. Because of its complicated structure, it is difficult and expensive to design and manufacture. Furthermore, it is difficult to provide a means for sliding each slide piece to open and close the mold in a proper order, making it difficult to improve molding accuracy and speed up molding speed.

In particular, the second slide piece is configured to be slid forward and backward relative to the first slide piece by spring action, but the spring action only takes 100% of the movement of the second slide piece.
It is extremely difficult to ensure reliability and can easily cause malfunctions and troubles.

In addition, the fourth slide piece is inserted into the middle part between the other first and second slide pieces and the third slide piece like a wedge and is slid forward and backward, but the temperature of the mold is controlled by the injection temperature of the molten resin. Because the molded product is cooled during solidification and ejection, there is a high possibility that the fourth slide piece may become unable to slide during such temperature changes and the accompanying phenomena of thermal expansion and contraction. There are problems in that surface accuracy cannot be maintained and burrs are likely to occur in the molded product, and these are issues that need to be solved.

Therefore, an object of the present invention is to provide an undercut forming device that has a simple configuration, has excellent mechanical operation certainty and reliability, and can improve forming accuracy and speed up forming speed. .

Means for Solving the Problems As a means for solving the problems of the prior art described above, an undercut forming device for a container forming mold according to this invention is provided, as a preferred embodiment is shown in the drawings. A container 1 having at least two protruding pieces 1b and 1d protruding outward from 1a, one protruding piece 1b having a bent or folded part 1e forming an angle on the side of the other protruding piece 1d. In an undercut molding device comprising a plurality of slide pieces in a container molding die for injection molding, (a) a first mold surface 5a having a mold surface 5a for molding the undercut portion between the two protruding pieces 1b and 1d; The second slide piece 6 has a mold surface 6a for forming the remainder of the same undercut portion and the bent surface or folded portion 1e.

(b) The first slide piece 5 slides horizontally by a distance _S4 such that the mold surface 5a is completely removed from the protruding pieces 1b and 1d while the male mold 3 is opened from the female mold main body 2 by a predetermined stroke _l5 . The female mold body 2 is tilted to
It was installed so as to be slidable along an inclined guide pin 8 fixed to.

(c) The second slide piece 6 is connected to a guide pin or dovetail groove guide mechanism in such a relationship that it can freely slide the lateral slide component that occurs when the first slide piece 5 slides along the inclined guide pin 8. 12 and 13, it is combined with the first slide piece 5. Moreover, the guide pins or dovetail groove guide mechanisms 12, 13 are formed at an inclination such that when the first slide piece 5 slides laterally by a predetermined distance m, the second slide piece 6 completely comes out of the bent part or folded part 1e, Furthermore, the sliding surfaces of the first and second sliding pieces 5 and 6 formed by the guide pins or dovetail groove guide mechanisms 12 and 13 include:
Notch steps 14 and 15 are formed that engage when the first slide piece 5 slides laterally by the distance m.

(d) A stopper block 11 with a height h is installed on the male mold 3 to restrict the lateral sliding of the _second slide piece 6 while the first slide piece 5 opens the mold from the female mold main body 2 to a predetermined stroke l2. However, this stopper block 11 and the second slide piece 6 are in a sliding relationship.

(e) A pulling body 17 is installed on the male mold 3 and extends toward the female mold 2 approximately parallel to the mold opening/closing direction, and the pulling body 17 which opens the mold with a constant stroke _l1 along with the male mold 3 is installed on the first slide piece. 17 engages the towed object 1.
8 is installed, and the engagement surface of the pulling body 17 engages with the towed body 18 when the first slide piece opens the mold together with the male die 3 to a certain stroke l ₁ , and the first slide piece slides horizontally in a predetermined direction. The first engaging surface 17b has a shape that disengages immediately before reaching the amount S ₄ , and the first engaging surface 17b has a constant step δ than the first engaging surface 17b.
The first
Each of them is characterized by comprising a second engagement surface 17c having a shape that disengages from the towed body 18 just before the slide piece reaches the maximum mold opening stroke _l5 .

In addition, an extrusion pin 16 is installed in the female mold main body 2 in the mold opening direction to push the container 1 in the mold opening direction when the second slide piece 6 slides in the direction of coming out from the bent part or folded part 1e. The second slide piece 6 has a positioning body 20 extending outward in parallel with the lateral sliding direction, and a stopper 21 for regulating the entry limit position of the positioning body 20 is provided on the female mold body 2 in the mold opening direction. Each of them is also characterized by having an arrangement extending to .

Action At the stage when the female die 2 and the male die 3 open by a certain stroke _l1 (Fig. 6A), the pulling body 17 engages with the towed body 18, and from then on, the first slide piece 5 moves to the male die. The side wall of the container 1, which is a molded product, slides along the inclined guide pin 8 along with the mold opening movement of step 3, and causes a lateral sliding component (movement in the direction of the arrow x in FIG. 7) based on the inclination of the inclined guide pin 8. It is released from the mold 1a and further comes off from the protruding pieces 1b and 1d (Fig. 7B, Fig. 8B).

The second slide piece 6 is restricted from lateral sliding by the stopper block 11 until the male mold 3 reaches the mold opening stroke of the height h of the stopper block 11, and the amount of lateral sliding is zero (Figs. 7 and 8B). . Therefore, as described above, a relative slide occurs between the first slide piece 5 and the second slide piece 6, which are causing lateral sliding, at the guide pin or dovetail groove guide mechanism 12, 13 that connects them. In relation to the container 1, which is a molded product, the second slide piece 6 moves in the direction of coming out of the bent portion or folded portion 1e (movement in the direction of the arrow y in FIG. 7B). The first slide piece 5 is the female body 2
When the mold is opened by a predetermined stroke _l2 , the second slide piece 6 almost leaves the folded part 1e of the molded product, and the guide pin or dovetail groove guide mechanism 12 connecting the first and second slide pieces 5, 6 is removed. ,1
Notch stepped portion 14,1 provided on the sliding surface of 3
5 engages (FIG. 8B). At this point, the towed body 18 is disengaged from the first engagement surface 17b of the towing body 17. Therefore, only the male die 3 and the container 1 have moved to open the mold, and when the male die 3 and the container 1 (molded product) have moved to open the mold by the step difference δ, the towed body 18 is moved to the towed body 1.
The second engaging surfaces 17c of No. 7 are engaged, and the mold opening movement of the first and second slide pieces 5 and 6 is resumed. As a result, the separation of the second slide piece 6 from the mold surface 6a and the folded portion 1e of the container 1 becomes larger and more complete, and the second slide piece 6 is no longer restricted by the stopper block 11 (see Fig. 9B). ).

Thereafter, the second slide piece 6 moves together with the first slide piece 5 to open the mold and slide sideways, and both pieces move toward the side wall 1a of the container 1, which is a molded product, and the protruding piece 1.
b and 1d, and finally the mold is completely demolded (FIG. 10B), and the container 1, which is a molded product, can be pushed out.

The push-out pin 16 pushes the container, which is a molded product, when the mold surface 6a of the second slide piece 6 moves in the y arrow direction (moves in the opposite direction to the mold opening direction) so that the mold surface 6a of the second slide piece 6 exits from the above-mentioned folded part 1e. 1 pushes in the same direction to follow the mold opening movement of male mold 3, so
The second slide piece 6 is reliably removed from the folded portion 1e of the mold surface 6a.

The mold closing and mold clamping processes of this undercut molding device are carried out by the male mold 3 moving to close the mold and pushing back the second slide piece 6 and the first slide piece 5 sequentially toward the female mold main body 2, thereby performing the mold opening process described above. It is performed in the reverse order and action. At this time, the positioning pin 20 prevents the second slide piece 6 from moving too far inward, and defines it at the position regulated by the stopper 21.

Example Next, the illustrated embodiment of the present invention will be described.

Container 1 molded with the container mold of this example
The shapes and structures of are shown in Figures 7A and B to Figure 9A,
As shown in B, protruding pieces 1b, 1c, and 1d protrude outward from the opening edge (lower edge in the figure) of the container side wall 1a, a position close to this, and a position at the bottom (upper edge in the figure), respectively. The protruding piece 1b at the edge of the opening has a folded part 1e bent at a substantially right angle to the side of the other protruding piece 1d. However, the present invention is also applicable to a structure in which the sliding piece forming the undercut portion, such as a bent portion forming a non-right angle, cannot simply be slid in the direction in which the projecting piece 1b projects.

Next, FIGS. 1 to 5A and 5B show a closed state of a container mold to which the undercut molding apparatus of this embodiment is applied.

In the figure, 2 is the female mold body (fixed side mold), 3 is the male mold (movable side mold), and 4 and 5 are the female molds divided into four by dividing the entire circumference of the rectangular container 1 into four sides. First slide pieces on the long side and short side are installed on the main body 2, and 6 is a second slide piece attached to the first slide piece 5 on the short side. Further, in the figure, 10 is a stopper block for regulating the slide of the first slide piece 4 on the long side, and 11 is a stopper block for regulating the slide of the second slide piece 6 on the short side, each of which is fixed to the male die 3. There is. In the figure, 30... is a guide pin of the male type 3.

The first slide piece 4 on the long side is used for forming three projecting pieces 1b, 1c, and 1d projecting outward from the container side wall 1a of the container 1 to be formed, and an undercut portion between these pieces. It has a mold surface 4a. As shown in FIG. 5A, the first slide piece 4 is installed so as to be slidable along an inclined guide pin 7 whose base end is fixed to the female body 2. The inclined guide pin 7 is configured such that the first slide piece 4 moves a predetermined stroke l ₂ from the female mold body 2 in the mold opening/closing direction.
Dimensions such that the mold surface 4a completely separates from each protruding piece 1b, 1c, 1d while the mold is opened by (Fig. 9A)
It is installed at an angle where it slides horizontally by S ₄ (Figure 9A). In the figure, 7a is a retaining flange provided at the tip of the inclined guide pin 7.

The first slide piece 5 on the short side also has two protruding pieces 1b that protrude outward from the container side wall 1a.
and 1d, and this first slide piece 5 is also installed so as to be slidable along an inclined guide pin 8 whose base end is fixed to the female mold body 2. . This inclined guide pin 8 is also lateral by a dimension S4 such that the mold surface 5a is completely removed from each of the protruding pieces 1b and 1d while the first slide piece 5 opens the mold by a predetermined stroke _l2 from the female mold main body ₂ . It is installed at an angle that allows it to slide (move in the direction of the arrow x) (Figure 9B). In the figure, 8a is a retaining flange provided at the tip of the inclined guide pin 8.

Adjacent first slide pieces 4 and 5 on the long side and short side are connected to each other by sliding pins 9 (Fig. 1), so that the mold opens in an integral relationship, and at the same time the required It is designed to slide horizontally by the dimensions.

The second slide piece 6 molds the remaining part of the undercut between the folded part 1e of the container 1 and the other protruding piece 1d that is insufficient on the mold surface 5a of the first slide piece 5, and the inside of the folded part 1e. It has a mold surface 6a. This second slide piece 6 and the first
The slide piece 5 is slidably assembled with the dovetail groove guide mechanisms 12 and 13 shown in FIG. That is, the first slide piece 5 has 1
A pair of dovetail groove rail members 12, 12 are fixed in parallel so as to face each other, and the dovetail groove rail members 1 are attached to both side surfaces of the T leg of the second slide piece 6, which is approximately T-shaped.
In the dovetail grooves 2 and 12, sliding dovetails 13 and 13 are formed, and both are slidably fitted together. This dovetail groove guide mechanism 12, 13
Also, when the first slide piece 5 slides sideways as described above, the mold surface 6a of the second slide piece 6 is moved in the direction of arrow y in FIG. 7B, and the folded part 1e is moved.
In the illustrated example, it is set at an angle of 30 degrees upward to the left with respect to the mold opening/closing direction.
Then, the first slide piece 5 is moved by the above-mentioned horizontal slide amount.
A stopper block 1 with a height h that restricts the lateral sliding of the second slide piece 6 while it slides horizontally by S ₄ .
1 is installed on the male die 3, and the outer surface 6b of the second slide piece 6 is slidably in contact with the slide regulating surface 11a of the stopper block 11. In other words, when the mold is opened, the outer surface 6b is the slide regulating surface 1.
1a, and during that period (mold opening stroke corresponding to the height h of the slide regulating surface 11a), the lateral sliding of the second sliding piece 6 is completely regulated by the stopper block 11, and the lateral sliding amount is zero.

Therefore, at this time, the first slide piece 5 and the second slide piece 6 cause a relative slide on the sliding surfaces of the dovetail groove guide mechanisms 12 and 13 by the amount of horizontal slide of the first slide piece 5, and therefore Based on the inclination θ of the dovetail groove guide mechanisms 12 and 13, the second slide piece 6 slides in the direction of the y arrow, and the second
The mold surface 6a of the slide piece 6 comes out of the folded portion 1e of the container 1.

Note that the stopper block 10 on the long side and the stopper block 11 on the short side each function to restrict the lateral sliding of the first slide pieces 4 and 5.
The relationship between the height h' of each slide regulating surface 10a, 11a and h is h'≦l ₁ <h (however, l ₁ is the mold opening stroke from the female mold body 2 of the male mold 3 = Fig. 6A ). The reason for this is that it is necessary to generate a required relative slide between the first slide piece 5 and the second slide piece 6 on the short side.

Furthermore, as shown in FIG. 5B, the slide surfaces of the first slide piece 5 and the second slide piece 6 formed by the dovetail groove guide mechanisms 12 and 13 have a substantially L shape that engages at a constant slide distance m. Notch steps 14 and 15 are formed. The slide distance m is the slide distance during which the first slide piece 5 opens the mold by a constant stroke _l2 from the female mold body 2, and is set based on the following consideration.

That is, as shown in FIG. 6B, the first and second slide pieces 5 and 6 remain immovable relative to the female mold body 2 until the male mold 3 is opened by a constant stroke _l1 from the female mold body 2. The mold is considered to be closed. For this purpose, the towed body 18 attached to the first slide piece 4 is set at a position where it engages with the towing body 17 attached to the male die 3 when the towing body 17 and the male die 3 open at a certain stroke _l1 . (The meaning of l ₁ will be explained later). Therefore, after the towing body 17 engages with the towed body 18, the second slide pieces 5 and 6 also engage the female body 2.
Start moving the mold to open the mold. Then, until the first slide piece 5 reaches a certain mold opening stroke l ₂ (FIG. 8B), the outer surface 6b of the second slide piece 6 comes into contact with the slide regulating surface 11a of the stopper block 11 and lateralizes. Due to slide regulations, the first
Only the slide piece 5 slides laterally along the inclination of the inclined guide pin 8, and the first slide piece 5, which has slid laterally in the direction of the arrow x in FIG. 8B, comes off the protruding piece 1d. Between the first slide piece 5 and the second slide piece 6, a relative slide occurs at the dovetail groove guide mechanisms 12 and 13, and as a result, the second slide piece 6 tilts the dovetail groove guide mechanisms 12 and 13. The mold surface 6a of the second slide piece 6 is moved in the direction of the arrow y in FIG. 8B based on θ, and the mold surface 6a of the second slide piece 6 is separates from the folded portion 1e of the container 1. Then, at the point when the outer surface 6b of the second slide piece 6 comes off the slide regulating surface 11a (at the stage where the first slide piece 5 has opened the mold by a certain stroke _l2 ), the vertical surface 14a of the notch steps 14 and 15 15a just engages. Thereafter, the first and second slide pieces 5 and 6 slide sideways together. That is, depending on the design of the slide distance m and the inclination θ of the dovetail groove guide mechanisms 12 and 13 with respect to this distance m, the dimension E (see Fig. 8B ) can be set over a wide range.

As described above, when the second slide piece 6 moves in the direction of the Y arrow to exit from the folded part 1d of the container 1, which is a molded product, the female mold is used as a means to actively press the container 1 toward the male mold 3. An extrusion pin 16 is installed in the main body 2 in an arrangement in the mold opening direction. As shown in FIG. 1, four push-out pins 16 are installed at the four corners of the container 1 (however, their positions and numbers are not limited to the illustrated example). This push-out pin 16 pushes the bottom of the container 1 with a certain force in advance when the second slide piece 6 moves in the direction of the arrow y and causes relative movement with the container 1, and pushes the container 1 against the second slide piece 6 in advance. The strong adhesive force prevents the two from moving together. Extrusion pin 1
6 indicates that the container 1 is in the eighth position in the mold opening process of the male mold 3.
It is sufficient to exert a pushing action to the extent that it does not move in the direction of the y arrow in Figure B.

The above-mentioned towed body 18 is protruded from both left and right sides of the first slide piece 4 on the long side in a direction perpendicular to the mold opening/closing direction, and the towed body 17 is protruded from the first slide piece 4 on the long side
They are installed as a pair on both the left and right sides of the slide piece 4. In particular, as shown in FIG. 3, the traction body 17 has a substantially hook shape oriented in the lateral sliding direction of the first slide piece 4 (rightward direction in the figure). The engaging surface of this hook portion 17a engages with the towed body 18 when the male die 3 and the pulling body 17 open the die by a certain stroke _l1 , and the first slide piece 4 engages with the towed body 18 by a predetermined lateral sliding amount.
Immediately before achieving S ₄ , the first engaging surface 17b is shaped to be disengaged, and the first engaging surface 17b is engaged with the towed object 18 at a position lower than the first engaging surface 17b by a certain step δ, Maximum mold opening stroke of the first slide piece l ₅
The second engaging surface 17c has a shape that disengages the towed body 18 just before reaching the second engaging surface 17c. The cross section of the towed body 18 is approximately square, and the towed body 17
The first and second engaging surfaces 17b and 17c are formed in two stages each approximately the length of one side of the square. In other words, the depth dimension ε of the hook portion 17a (Fig. 3)
is equal to or less than twice the length of one side of the towed object 18 as described above, and the first side on the long side
Slightly smaller than the total horizontal slide dimension _S5 when slide piece 4 reaches the maximum mold opening stroke _L7 , and the first
When the slide piece 4 completes the lateral sliding amount _S4 , the length is such that the towing body 17 and the towed body 18 are completely disengaged.

Also, the size of the step δ is determined by the fact that the second slide piece 6 is moved by the arrow y by using the horizontal slide of the first slide piece 5.
direction, and the mold surface 6a forms the folded part 1 of the container 1.
After exiting by depth dimension E (FIG. 8B) of e, it serves to make the withdrawal larger and more complete. That is, the first engagement surface 17b of the pulling body 17 and the towed body 18 are disengaged when the mold surface 6a of the second slide piece 6 comes out of the folded portion 1e in the state shown in FIG. 8B. , until the towed body 18 is next engaged with the second engagement surface 17c, the male die 3 and the container 1
Only the mold opening movement proceeds, and the first and second slide pieces 5 and 6 remain stationary. Therefore, the distance between the mold surface 6a and the folded portion 1e is increased by the step difference δ.
Therefore, a slight step difference δ is sufficient, and in practice it is in the range of several mm.

The meaning of the distance l ₁ between the towed body 18 and the first engaging surface 17b of the pulling body 17 in the closed state of the mold in FIG. It is said to have a size (approximately several tens of millimeters) that is necessary and sufficient for peeling and mold release. Therefore, at the beginning of the mold opening process, the pulling body 17 is idle until the male mold 3 reaches the mold opening stroke corresponding to the above-mentioned interval _l1 , and the first and second slide pieces 4, 5, 6 remains stationary, and the molded product container 1 attached to them also remains stationary, so only the male mold 3 moves to open the mold and peels and releases from the molded product container 1 ( Figure 6 A, B).

When the mold opening stroke of the male mold 3 reaches the above-mentioned interval l ₁ , the first engaging surface 17b of the pulling body 17 engages with the towed body 18, and thereafter, together with the male mold 3, the first and second engaging surfaces 17b engage with the towed body 18.
Slide pieces 4, 5, and 6 also move to open the mold. Therefore, the container 1, which is a molded product, also moves together with the male die 3 while remaining spaced apart from it by the distance _l1 . For this reason, the first
The slide pieces 4, 5 cause horizontal sliding along the inclined guide pins 7, 8 and come off the protruding pieces 1b, 1d. Therefore, the engagement dimension between the towed body 18 and the first engagement surface 17b of the towing body 17 gradually decreases. The mold opening stroke of the first slide piece 5 is a predetermined size l ₂
(Fig. 8A, B), the first slide piece 4,
5 is completely removed from each protruding piece 1b, 1c, 1d,
The mold surface 6a of the second slide piece 6 is the folded part 1e.
(Fig. 8B), and the first and second
The notch steps 14 and 15 of the slide pieces 5 and 6 are engaged, and the towed body 18 is engaged with the first engagement surface 17 of the towing body 17.
b, and is located apart from the second engagement surface 17c by a step difference δ. Therefore, when the mold opening stroke of the male mold 3 advances by the step δ, the molded single surface 6a of the second slide piece 6 is further removed from the folded portion 1e. Then, since the towed body 18 comes to engage with the second engagement surface 17c of the towing body 17,
Thereafter, as the mold opening stroke of the male die 3 progresses, the first slide piece 5 and the second slide piece 6 move in an integral relationship along the inclined guide pin 8, and the respective mold surfaces 5a and 6a are aligned with the container 1. far away from

Immediately before the first and second slide pieces 5 and 6 reach the maximum mold opening stroke _l7 (Fig. 10B), the engagement between the pulling body 17 and the towed body 18 is disengaged in the lateral direction, and immediately after that, the first sliding piece The slide piece 5 collides with the retaining flange 8a of the inclined guide pin 8 and stops moving.

After this, the mold opening process of the male mold 3 further progresses, and the container 1, which is a molded product, is pushed down.

The mold-closing and mold-clamping processes of the first and second slide pieces 4, 5, and 6 are performed in the exact opposite order and operation to the mold-opening process by the male die 3 of the mold-closing process pushing them back. be exposed. At this time, in order to prevent the second slide piece 6 from going too far inward and colliding with the male die 3, the second slide piece 6 is provided with a positioning pin that extends outward in the lateral direction (sliding direction). 20 are installed. In the figure, 20a is a positioning flange. On the other hand, a stopper piece 21 is installed on the female mold main body 2 with its base end fixed to the female mold main body 2 and arranged parallel to the mold opening direction, and the stopper piece 21 is set at the entry limit position of the second slide piece 6 via a positioning flange 20a. It is said that the structure stipulates the following.

Effects of the present invention As described above in detail together with the embodiments, the undercut forming device for a container molding die according to this invention has two types of first and second slide pieces 5 and 6. Since the main components are very simple, the design and manufacture are easy and inexpensive. Moreover, even if the first and second slide pieces 5 and 6 are used as a means for opening and closing the mold in a predetermined order, the pulling body 17, the towed body 18, the stopper block 11, the inclined guide pin 8, the dovetail groove guide mechanism 12, About 13 is sufficient, and since these have excellent mechanical operation certainty and reliability, it is possible to improve molding accuracy and increase molding speed.

In particular, the engagement surface of the traction body 17 has a first surface with a step δ.
Since it is made up of the engagement surface 17b and the second engagement surface 17c, the gap between the mold surface 6a of the second slide piece 6 and the folded portion 1e of the container 1 can be made larger and perfect by the step difference δ. Therefore, the inclined guide pin 8 can be shortened accordingly, and the width dimension of the undercut forming device can be shortened to make it more compact.
There is also the advantage that the depth E can be designed to be wide.

and at least 2 points outwardly from the container side wall 1a.
It has one protruding piece 1b, 1d.
Even if the undercut of the container 1 having a bent part or folded part 1e that forms an angle with the other projecting piece 1d is deep to some extent, or the shape and structure of the bent part or folded part 1e are designed within a certain range. Even if the undercut is changed, the undercut can be handled reliably, so there is a wide tolerance for the shape and structure of the container, especially the one that causes the undercut.This allows for a high degree of freedom in container design, allowing for easy and efficient injection molding. .

Moreover, the container 1 which is a molded product has an extrusion pin 16
Since the container 1 can be reliably attached to the male mold 3 and opened, it is extremely convenient for automatic dropping of the container 1.

[Brief explanation of drawings]

The drawings show a mold for molding containers to which the undercut molding device according to the invention is applied, and FIG.
Figures 2 to 4 are sectional views taken along the -, -, - lines in Figure 1, Figure 5A, Figure 6A, Figure 7A, and Figure 8A. , Figure 9A,
Figure 10A is taken from the a-a line arrow view of Figure 1, and Figures 5B, 6B, 7B, 8B, 9B, and 10B are 2A and 2B are cross-sectional views taken along line b-b in FIG. 1 and showing important states of the mold opening process, respectively; FIG.

Claims (1)

[Claims for Utility Model Registration] (1) It has at least two protruding pieces 1b and 1d that protrude outward from the container side wall 1a, and one protruding piece 1b is on the side of the other protruding piece 1d. In an undercut molding device consisting of a plurality of slide pieces in a container molding die for injection molding a container 1 having an angled bent portion or folded portion 1e, a. A first slide piece 5 having a mold surface 5a for forming an undercut portion, the remainder of the same undercut portion, and the bent surface or folded portion 1
(b) The first slide piece 5 performs molding while the male die 3 opens from the female die main body 2 by a predetermined stroke _l5 . The mold surface 5a is installed so as to be slidable along the inclined guide pin 8 fixed to the female mold main body 2 at an inclination to horizontally slide by a distance _S4 at which the mold surface 5a is completely removed from the protruding pieces 1b and 1d, and (c) the second slide. The piece 6 is first slid by guide pins or dovetail groove guide mechanisms 12 and 13 in a slidable relationship to prevent a lateral slide component that occurs as the first slide piece 5 slides along the inclined guide pin 8. The guide pin or dovetail groove guide mechanisms 12 and 13 are combined with the piece 5, and when the first slide piece 5 slides laterally by a predetermined distance m, the second slide piece 6 completely comes out of the bent portion or folded portion 1e. The guide pin or dovetail groove guide mechanism 1 of the first and second slide pieces 5 and 6 is formed with an inclination.
2, 13 are formed with cutout stepped portions 14, 15 that engage when the first slide piece 5 slides horizontally by the distance (m); A stopper block 11 with a height (h) is installed to restrict the lateral sliding of the second slide piece 6 while the first slide piece 5 is opening the mold from the female mold body 2 to a certain stroke (l ₂ ). and the second slide piece 6 are in a sliding relationship. E) The female mold 2 is attached to the male mold 3 approximately parallel to the mold opening/closing direction.
A towing body 17 is installed that extends toward the first
A towed body 18 is installed on the slide piece at a position where the towed body 17 is engaged with the male die 3 and the towed body 17 which is opened by a certain stroke (l ₁ ).
The engagement surface of the pulling body 17 engages with the towed body 18 when the first slide piece opens a certain stroke (l ₁ ) together with the male die 3, and the first slide piece engages with the towed body 18 by a predetermined lateral sliding amount (S ₄ ). The first engaging surface 17b is shaped such that the engagement is released just before the first engaging surface 17b is reached, and then the first engaging surface 17b engages with the towed object 18 at a position lower than the first engaging surface 17b by a certain step δ, and the first slide An undercut in a container molding die, each comprising a second engagement surface 17c having a shape that disengages from the towed body 18 just before the piece reaches the maximum mold opening stroke (l ₅ ). Molding equipment. (2) A push-out pin 16 is installed in the female mold main body 2 in the mold opening direction to push the container 1 in the mold opening direction when the second slide piece 6 slides in the direction of coming out from the bent part or folded part 1e. An undercut forming apparatus for a container forming mold as set forth in claim 1 of the utility model registration claim. (3) The second slide piece 6 has a positioning body 20 that extends outward in parallel with the lateral sliding direction, and the female mold body 2 has a stopper 21 that restricts the entry limit position of the positioning body 20 in the mold opening direction. An undercut forming device for a container forming mold as set forth in claim 1 or 2 of the utility model registration claim, characterized in that the undercut forming device has an arrangement extending over the entire length of the container.