JPH0242423Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a mold for injection molding a plurality of tubular products in one cycle.

(Prior art) Conventional molds for injection molding multiple tubular products in one cycle include a fixed mold and a movable mold that can be opened and closed with each other, and multiple cavities are moved up and down between these molds. The movable mold has a core mold for each cavity.

(Problem to be solved by the invention) In the mold with the above configuration, when the mold is released, the product that falls from the upper stage may land on the core mold in the lower stage, and this falling failure may cause double pressing, etc. , which hindered the smooth operation of automatic molding.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is to provide a fixed type and a movable type that can be opened and closed with each other. In an injection mold in which multiple cavities are arranged vertically between the movable mold and a core mold is provided for each cavity in the movable mold, by providing a step between the parting surfaces of the fixed mold and the movable mold. , an injection mold for a tubular product, characterized in that the upper part of the parting surface of the movable mold is protruded from the lower part, and the upper cavity and core mold are offset toward the fixed mold than the lower cavity and core mold. It is in.

(Function) Products that are released from the upper part of the parting surface of the movable mold and fall will not land on the lower core mold because the upper part of the parting surface protrudes more than the lower part.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. The drawing shows a mold for injection molding four bent pipes (tubular products) made of vinyl chloride resin in one cycle. In the figure, 10 is a fixed type, and 20 is a fixed type 10.
It is a movable type that closes and opens by moving against.

The parting surface 21 of the movable mold 20 has two steps 22 extending in the horizontal direction and two steps extending in the vertical direction.
A step 23 between the stripes is formed. Each horizontal step 2
2 and the vertical step 23 are connected at right angles. The two horizontal steps 22 are formed on the same straight line, and the upper part 21a of the parting surface 21 is made to protrude more than the lower both sides 21b. Moreover, the two vertical steps 23 are parallel to each other, and the lower central part 21c of the parting surface 21 is connected to the lower both sides 21 of the parting surface 21.
It is made to protrude from b. Note that the parting surface 11 of the fixed mold 10 is the parting surface 2 of the movable mold 20.
1, and has steps 12 and 13 corresponding to the steps 22 and 23 described above.

Four cavities 30 are formed between the fixed mold 10 and the movable mold 20. The two upper cavities 30 are located at the upper part 21 of the parting surface 21.
In a, it is formed separately on the left and right. Further, the two lower cavities 30 are formed on the lower side portions 21b of the parting surface 21, respectively.

The movable mold 20 includes a horizontally movable core mold 31 and a vertically movable core mold 32 for each cavity 30.
is provided. When the core molds 31 and 32 are closed, their end surfaces 31a and 32a are in contact with each other in the cavity 30 as shown in FIG.
A molding space corresponding to a curved pipe 50, which will be described later, is formed between the outer surfaces of the pipes 1 and 32. Further, the core molds 31 and 32 are designed to retreat from the cavity 30 when the mold is opened and split.

As mentioned above, the upper part 2 of the parting surface 21
1a protrudes from the lower both sides 21b,
Upper cavity 30 and core molds 31, 32
is the lower cavity 30 and core molds 31, 3.
2, it is deviated toward the fixed mold 10 direction. Also,
The interval between the two upper cavities 30 is the same as that of the lower two cavities 30.
Therefore, the upper cavity 30 and core molds 31, 32 are spaced in a direction parallel to the parting surface 21 with respect to the lower cavity 30 and core molds 31, 32. is also deviated.

Between the fixed mold 10 and the movable mold 20, there is a fixed mold 1
A plurality of runners 33 are formed which communicate with a sprue (not shown). As shown in FIG. 3, the runner 33 has a vertical portion 33a extending vertically from the sprue up and down, and horizontal portions 33b and 33c extending horizontally from the upper and lower ends of the vertical portion 33a. The lower horizontal portion 33c extends from the lower central portion 21c of the parting surface 21 toward the lower both side portions 21b, and has a U-shape in plan.
As shown in FIG. 4, a gate 34 is formed inside the movable mold 20 to communicate the runner 33 and the cavity 30. As shown in FIG. This gate 34
is formed short and has a diameter comparable to or thinner than the thickness of the curved pipe 50, forming a so-called pinpoint gate.

As shown in FIG. 4, the movable mold 20 has a heater 3.
5 and a temperature sensor 36 are embedded,
This temperature sensor 36 detects the temperature near the gate 34, and based on this detected temperature, the heater 35
The temperature of the gate 34 is controlled to about 50~50℃.
It is designed to be kept at 120℃.

A space 37 for forming an undercut portion is formed in the movable mold 20 at the location of the sprue and runner 33. These spaces 37 have a large diameter section 3 in the middle.
7a. An ejector pin 38 is arranged at the rear of the space 37. Further, as shown in FIG. 3, the movable mold 20 is provided with an ejector pin 39 corresponding to each cavity 30.

In the above configuration, molten vinyl chloride resin is injected with the fixed mold 10 and the movable mold 20 closed. The injected molten resin is filled from the sprue of the fixed mold 10 through the runner 33 and the gate 34 into the cavity 30. Generally, in the case of vinyl chloride resin, if the diameter of the gate 34 is smaller than the product wall thickness, the injection pressure in the cavity 30 will be low, resulting in poor appearance of the product. Since the vicinity of the gate 34 is heated, the molten resin can smoothly flow inside the gate 34, and as a result, the injection pressure inside the cavity 30 can be prevented from decreasing, so that the product does not have a defective appearance.

The molten resin is cooled and solidified within the cavity 30 to form a bent pipe 50 as a product. Furthermore, the molten resin is cooled and solidified in the sprue and runner 33, forming a sprue portion 51 and a runner portion 52, respectively. Further, the resin solidified in the space 37 provides an undercut portion (not shown) that is integrated with the sprue portion 51 and the runner portion 52.

In the process of cooling and solidifying the molten resin, heating by the heater 35 continues, and the gate 34
The resin (gate portion 53) is maintained in a softened state.

Next, the movable mold 20 is moved to separate both molds 10 and 20. At the same time as this splitting, the core molds 31 and 32 are moved back and removed from the curved pipe 50. Thereafter, the bent pipe 50 is released from the movable mold 20 by the ejecting pin 39. In addition, the sprue part 51 and the runner part 52
Since the undercut portion that is integral with the movable mold 20 fits into the space 37, the sprue portion 51 and the runner portion 52 remain in the movable mold 20 without being released from the mold. When the bent pipe 50 is released from the mold, the gate portion 53 is pulled and cut. Since the gate portion 53 is in a softened state and has a small diameter, it is easily cut. As mentioned above, the runner part 52 and the bent pipe 50 are automatically connected to each other.
can be separated, and manual separation work can be omitted.

After the bent pipe 50 is released from the mold, the sprue portion 51 and the runner portion 52 are released from the mold using the ejector pin 38 while remaining integral. Note that this mold release may be performed simultaneously with the mold release of the curved pipe 50.

The above cavity 30 and core molds 31, 32
However, the lower cavity 30 and core molds 31, 3
2, it is deviated in the direction of the fixed mold 10 and also in the direction parallel to the parting surface 21, so when the upper bent pipe 50 is released from the mold and falls, the lower part is deviated. It will not get caught on the core molds 31, 32.

Further, the lower horizontal portion 52c of the runner portion 52 is
The parting surface 21 has a U-shape extending from the lower central part 21c to the lower both sides 21b, and extends over the protruding lower central part 21c, so that the runner part 52 does not tilt during mold release. However, it is guided by the vertically extending lower central portion 21c and falls straight, without being caught by the lower core molds 31, 32. Further, the upper horizontal part 52b of the runner part 52 is connected to the lower two sets of core molds 31, 3.
2, this upper end horizontal portion 52
b can be prevented from getting caught on the lower core molds 31, 32.

As a result, it is possible to prevent the bending pipe 50, the runner portion 52, etc. from falling, and it is possible to prevent problems such as double pressing, which interfere with automatic molding.

The present invention is not limited to the above embodiments and can be modified in various ways. For example, in the above embodiment, the product was released from the mold using the ejector pin, but the product may be released from the mold by moving the core mold away from the parting surface of the movable mold. In addition, the mold of this invention can be used not only with vinyl chloride resin, but also with
It can also be used to mold thermoplastic resins such as polyolefin and polystyrene.

(Effect of the invention) As explained above, in the present invention, a step is provided on the parting surface of the movable type, the upper part of this parting surface protrudes from the lower part, and the upper cavity and core mold are connected to the lower cavity and core. Since it is deviated toward the fixed mold rather than the mold, when the product is released from the mold, the product on the upper stage does not get caught by the core mold on the lower stage. Therefore, it is possible to prevent falling failures, and it is possible to prevent problems such as double pressing, which interfere with automatic molding.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention; Fig. 1 is a perspective view of the movable mold, Fig. 2 is a longitudinal sectional view of the main parts of the mold in the closed state, and Fig. 3 is a longitudinal sectional view of the molded resin. The front view of the movable type shown in Figure 4 is shown in Figure 3.
FIG. 10... Fixed type, 20... Mobile type, 11, 21
... Parting surface, 21a ... Upper part of parting surface, 21b ... Lower both sides of parting surface, 22 ... Horizontal step, 30 ... Cavity, 3
1, 32...Core type, 50...Bent pipe (tubular product).

Claims (1)

[Scope of utility model registration request] It has a fixed type and a movable type that can be opened and closed with each other, a plurality of cavities are arranged above and below between the fixed type and the movable type, and a core mold is provided for each cavity in the movable type. In injection molding molds, by providing a step between the parting surfaces of the fixed mold and the movable mold, the upper part of the parting surface of the movable mold protrudes more than the lower part, and the upper cavity and core mold are lower than the lower cavity and core mold. An injection mold for tubular products, characterized by being deviated in the direction of the fixed mold.