JP2530245Y2 - U-shaped tube forming mold - 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 for forming a U-shaped tube, and more particularly to a mold for integrally forming U-shaped tubes (J-shaped tubes) having different straight portions by injection molding of plastic.

[0002]

2. Description of the Related Art As a mold for integrally molding a U-shaped tube by injection molding of plastic, for example, Japanese Patent Application Laid-Open No. 61-2487.
As described in Japanese Patent Publication No. 16, a fixed type having therein a U-shaped concave portion corresponding to the outer shape of a U-shaped tube, a pair of mouth shapes corresponding to a straight pipe portion of the U-shaped tube, and an arc portion of the U-shaped tube And a movable type having a pair of rotating inner dies corresponding to the above.

[0003] In such a U-tube molding die, when the movable die is removed from the fixed die after the molding, the mouth die is linearly extracted, and at the same time, the rotating inner die is attached to the straight pipe portion of the U-tube. It is configured to rotate to a position where it does not interfere and then withdraw.

[0004]

[Problems to be Solved by the Invention] However, U-shaped pipes often used for water distribution pipe joints are, for example, Japanese Utility Model Laid-Open No. 64-2.
As shown in Japanese Patent No. 4174, those having different straight pipe portions (J-shaped pipes) are often used. On the other hand, in the conventional U-tube forming mold, the dividing position of the rotating inner mold is divided at the bottom of the U-tube, that is, at an angle of about 90 degrees.
When the straight pipe sections have different lengths and the ends of the U-shaped pipes have the same inner diameter, if the diameters of both bores and the draft of the movable mold are the same, the straight pipe section has a longer turning depth. Since the outer diameter of the mold is reduced, a step is generated at the abutting portion of each rotating inner mold.

[0005] In order to eliminate the above-mentioned step, the outer diameter of the contact portion of each rotating inner mold is made the same, and the diameter of the shorter straight pipe portion and the draft of the rotating inner mold are appropriately set. Since the diameter of the longer straight pipe part and the draft angle of the rotating inner mold become smaller,
The mold releasability is reduced, the mold release balance between both pipe parts is deteriorated, and it is easy to cause a mold release trouble at the time of production. Conversely, if the diameter of the straight pipe part is longer and the draft of the rotating inner mold is sufficiently taken, the outer diameter of the rotating inner mold becomes smaller, so the inner diameter of the arc part of the obtained U-shaped pipe becomes excessively small, and drainage occurs. Efficiency will be reduced.

[0006] Therefore, the present invention provides U
It is an object of the present invention to provide a U-tube forming die capable of efficiently producing a U-shaped tube (J-shaped tube) and having a sufficiently large inner diameter of an arc portion.

[0007]

In order to achieve the above-mentioned object, a U-shaped tube forming die according to the present invention comprises a fixed die having a U-shaped recess therein and a pair of U-shaped tubes corresponding to a straight pipe portion of the U-shaped pipe. In a U-tube molding die having a mouth mold of the type described above and a movable mold having a pair of rotating inner molds corresponding to the arc portion of the U-shaped pipe, the contact surface of the rotating inner mold is formed by a U-shaped pipe. Are located on a line connecting substantially equidistant points from the end of the U-shaped tube along the axis of the circle and the center point inside the arc portion.

[0008]

[Operation] According to the above configuration, both the diameter and the draft angle of the rotary inner mold can be made the same, and the release area can be made substantially the same.
Accordingly, no step is generated at the contact portion of the rotating back mold, troubles in mold release failure can be reduced, and the inner diameter of the arc portion can be made sufficiently large.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

The U-shaped tube forming mold 10 includes a fixed mold (female mold) 11 having a half-split structure and a U-shaped mold formed in the fixed mold 11.
And a movable type (male type) 13 inserted into the character-shaped concave portion 12. Mobile 13 has a pair of mouth type 14a corresponding to the straight tube portion P ₁ of the U-tube P, respectively, 14b, a pair of pivot back type 15a corresponding to the arc portion P ₂ of the U-shaped pipe P, 15
b and a base portion 16 for supporting these.

The mouth dies 14a and 14b are formed to have lengths corresponding to the lengths of the respective straight pipe portions, and a base portion 14c is formed integrally therewith. Is provided movably in the axial direction of the U-shaped tube P. At the rear end of the base part 16, crank rings 17, 17 are provided rotatably. The crank ring 17 is provided about a point on a straight line that is parallel to the axis of the U-shaped pipe P and passes through the center of the arc of the U-shaped pipe P as a center of rotation. 15a and 15b are connected by a parallel crank 20 including a pair of connecting shafts 18 and 19 parallel to the axis of the U-shaped pipe P penetrating through the mouth dies 14a and 14b. Further, on the side of the mouth dies 14a and 14b of the crank ring 17, an arcuate surface 17a that comes into contact with the rear ends of the mouth dies 14a and 14b at the time of die cutting, which will be described later, is connected to the connection shaft 18 far from the rotation center. It is formed around the connection point 18a.

[0012] The crank ring 17 and the rotary back mold 15
Of the connecting shafts 18 and 19 connecting the a and 15b to each other, the connecting shaft 19 on the side closer to the center of rotation of both of them is a rotating back mold 15a, 1
In order to maintain the positional accuracy between the die 5b and the die 14a, 14b, the moving direction is guided to through holes formed in the respective die 14a, 14b. Therefore, a connection point 19 between the connection shaft 19 and the crank ring 17 is formed.
“a” is provided to be slightly movable by a long hole 17 b formed in the radial direction of the crank ring 17 in order to absorb a change in the relative position between the two. On the other hand, the connecting shaft 18 farther from the rotation center is connected to the crank ring 17 and the rotation inner mold 1.
In order to cope with the position change accompanying the rotation of 5a, 15b,
It is loosely inserted into a large-diameter through hole formed in the mouth dies 14a and 14b.

Here, the trajectory of the imaginary turning center A of the turning inner molds 15a and 15b which are turned by the parallel crank 20 does not correspond to the inner surface of the molded product. The connecting points 18b and 19b between the rotary inner dies 15a and 15b and the two connecting shafts 18 and 19 are located within the range where the respective components do not come into contact with the molded product and sufficiently resist the molding injection pressure. Is set to a position where it can be obtained. In addition, the rotation center B of the crank ring 17, the two connecting shafts 18,
The connection points 18a and 19a with the connecting member 19 are also provided at positions where sufficient strength against the molding injection pressure can be obtained and the operation space of each component can be secured.

The crank ring 17 is provided with a spring 21 for urging the crank ring 17 in the direction of the fixed mold 11, and the abutment surface of each mold ensures that the abutting state of the molds is maintained. Uneven portion 22 is formed.

In the mold according to the present invention, as shown in FIG. 2, the contact surfaces (divided portions) S of the rotating inner molds 15a and 15b are formed in a U-shape along the axis of the U-shaped tube P. Pipe ends X, Z
And is located on a line connecting the inner center point of the substantially equal distances points Y and the circular arc portion P ₂ A '(point of the molded article inside surface corresponding to the rotation center A) from. That is, the distances La and Lb along the respective axes from the U-tube end surfaces Sa and Sb of the mouth dies 14a and 14b to the contact surfaces S of the rotary inner dies 15a and 15b are set to be substantially equal. doing.

In such positions, the rotary inner molds 15a, 15b are located.
By setting the contact surface S of the
Even when the draft angles of the rotary inner molds 15a and 15b are the same, no step occurs at the contact portions of the rotary inner molds 15a and 15b, and the release area can be made substantially the same. Therefore, it is possible to reduce the mold sticking problems, can be a shape of the contact surface S in substantially the same, and since the inner shape of the smooth transition is obtained, the inner diameter of the arcuate portion P ₂ of the U-shaped tube P It is possible to take a sufficiently large,
Drainage efficiency can be improved.

When the molding of the U-shaped pipe P is completed, the U-shaped pipe forming die 10 first moves on the base portion 16 in a direction away from the fixed mold 11, so that the U-shaped pipe 1 is moved.
4a, 14b, rear end of base 14c and crank ring 17
Abuts against the circular arc surface 17a. The mouth mold 14a so far,
The distance of movement of the rotary molds 14a, 15b should be greater than the position where the rotation of the rotary inner molds 15a, 15b does not interfere with the rotary molds 14a, 14b.
a, 14b are set to the distances away from the rotating inner molds 15a, 15b.

When the mouth dies 14a and 14b further move from this position, the crank ring 17 rotates with the movement of the mouth dies 14a and 14b, and as shown in FIG. The molds 15a and 15b are rotated to an extractable angle. The moving distance of the mouth dies 14a and 14b up to this point is determined by the fact that the maximum dimension of the rotating inner dies 15a and 15b is
To the position perpendicular to the axial direction of
15b is set to a distance that can be rotated. At this time, the rotating inner dies 15a and 15b
Since it is rotated by the operation of the parallel link 20 accompanying the rotation of 7, the sliding contact with the inner peripheral surface of the molded product can be minimized. Further, since the turning inner dies 15a and 15b at the time of turning are supported by the parallel crank 20 supported by the crank ring 17 and the mouth dies 14a and 14b, the supporting strength is improved, and the turning inner dies 15a and 15b are improved. The position of 15b can be stabilized.

Subsequently, the entire movable die 13 is linearly moved along with the base portion 16 in the pulling-out direction, so that the die 14a, 1
4b and the rotating inner molds 15a and 15b can be extracted from the molded product. Thereafter, the U-shaped pipe P after molding can be taken out by dividing the fixed mold 11 as in the conventional case.

In the present invention, the movable pulling mechanism is not particularly limited. Even if another pulling mechanism is employed, the contact surface of the rotary back type is set as described above. By doing so, a similar effect can be achieved.

[0021]

As described above, in the U-tube forming die of the present invention, the abutment surface of the rotating inner mold is substantially equidistant from the end of the U-tube along the axis of the U-tube. Since it is located on the line connecting the point and the inner center point of the arc part, even when forming U-shaped pipes having different lengths of the straight pipe part, the draft angles of both the mouth mold and the rotating inner mold can be made the same. In addition, since the mold release area can be made substantially the same, molding failure trouble during production is reduced. In addition, since the draft angle becomes the same, the shape of the rotary back-type divided portion can be made substantially the same, and the inner surface shape has a smooth connection, so that the maximum drainage efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a U-tube molding die of the present invention.

FIG. 2 is an explanatory diagram of a position of a contact surface of a rotary back type.

FIG. 3 is a cross-sectional view showing a process of extracting a movable mold.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... U-tube molding die 11 ... Fixed mold 13 ... Moving mold 14a, 14b ... Mouth mold 15a, 15b ... Rotating back mold L ... U-tube axis La, Lb ... Distance P
… U-shaped pipe P ₁ … Straight pipe P ₂ … Circular arc S… Contact surface

Claims (1)

(57) [Scope of request for utility model registration] 1. A fixed type (1) having a U-shaped recess (12) therein.
1), a pair corresponding to the pair of mouth type corresponding to the straight tube portion of the U-tube _{(P) (P 1) (} 14a), ( arc portion 14b) and the U-tube (P) (P ₂₎ (1a) and (5b)
3), the contact surface of the rotating inner molds (15a) and (15b) is set to the axis (L) of the U-tube (P).
Is located on a line connecting a substantially equidistant point (Y) from the end portions (X) and (Z) of the U-shaped pipe along the center line and an inner center point (A ′) of the arc portion (P ₂ ). Characteristic U-tube molding die.