JP2887859B2 - Method and apparatus for forming threaded parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a threaded part having a female thread on an inner peripheral surface.

[0002]

2. Description of the Related Art Conventionally, when molding a threaded component having a female thread portion, a screw core having a male thread portion on an outer peripheral surface is provided in a mold, and a molten resin is injected into a cavity of the mold to form the molten core. After the resin is cooled and solidified in the cavity to obtain a molded product, by rotating the screw core, the male screw portion of the screw core is loosened from the female screw portion of the molded product, and then the mold is removed. The mold was to be opened. As a driving device for rotating the screw core, a motor as a drive source, a gear train transmitting the driving force of the motor to the screw core, and the like are used.

[0003]

In the prior art described above, since the molten resin shrinks when cooled and solidified in the cavity of the mold, the female screw portion of the solidified molded product becomes the male screw portion of the screw core. When the female screw is loosened, the periphery of the female screw is in contact with the wall of the mold, that is, both the inside and the outside of the female screw are firmly held. Has a large rotational resistance, and a large driving force is required to rotate the screw core. For this reason, there is a problem that a motor as a driving source becomes large and costs increase. In particular, when the female screw portion is eccentric with respect to the rotation center of the screw core, a larger driving force is required.

The present invention has been made in view of such circumstances in the prior art, and an object thereof is to provide a female screw on an inner peripheral surface.
A driving force required for rotation of a screw core provided in a mold used for manufacturing a threaded part having a portion can be reduced, and a low-cost method of forming a threaded part and
And a molding device therefor.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a threaded part for forming a molded product having a female thread on an inner peripheral surface, wherein the thread core has a male thread on an outer peripheral surface. Provided slidably in the axial direction of the screw core
And a second mold facing the first mold.
After injecting a molten resin into the cavity of the mold formed by abutting the mold against the mold, cooling and solidifying the molten resin in the cavity to obtain a molded product, the screw core,
Maintain a state in which the molded article and the second mold are integrated.
Holding the screws of the first and second molds
The core is opened slightly in the axial direction to form a clearance around the female screw portion of the molded product.
This is achieved by loosening the screw core from the female screw portion by rotating the screw core while maintaining the contact state between the second mold and the molded product .

[0006] Another object of the present invention described above, the first and that is used for molding a molded article having an internal thread portion on the inner peripheral surface
A second mold, in the molding apparatus of the threaded part having a screw core with an external thread portion that corresponds to the female <br/> threaded portion of the molded article into said first mold, said first 1 and the said
Mold 2 has clearance around the female thread of the molded product
Slightly spaced in the axial direction of the screw core to obtain
In order to eject the molded product in the first mold opening state
In the direction above the first mold open state.
And it is possible to open the second mold open mold and state, the first
The mold side and a motor for rotating the screw core, wherein
A rotational force transmitting means you transmitting the rotational force of the motor to the screw core, axial said threaded core relative to the first mold
To Rukoto equipped with a sliding support means for slidably supported in
And the caps of the first and second dies that abut against each other.
Molded product was obtained by cooling and solidifying the molten resin in the cavity
The first of the first and second molds to be performed later
When opening the mold to the mold opening state, the screw core and the component
Maintains a state in which the shape and the second mold are integrated
And a clearer around the female thread of the molded product.
This is achieved by having a sense formed .

[0007]

According to the method of forming a threaded part of the present invention, since the clearance is formed around the female screw portion of the molded product by opening the mold as described above, when the screw core is rotated, The periphery of the female screw portion is in a free state that is not restricted by the mold wall portion, that is,
The rotational resistance is reduced by the elastic deformation of the female screw portion to the outside. Thereby, the driving force required for rotating the screw core can be reduced.

Further, in the molding apparatus of the threaded part of the present invention, injecting a molten resin into the mold cavity, after obtaining a molded article which is cooled and solidified, slightly mold opening of the mold <br/> When performing the amount (first mold open state) , screw core, molded product and
In <br/> remain state preliminary and second mold are integrated is maintained, the screw core is moved relative to the first mold. As a result, a clearance is formed around the female screw portion of the molded product, and the circumference of the female screw portion is in a free state that is not restricted by the wall of the first mold. Then, it via a rotational force transmission means driven by a motor in this state
Rotation of the Flip core, the screw core is loosened from rotating the female screw portion.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an essential part showing an embodiment of a molding device for threaded parts of the present invention, FIG. 2 is a plan view showing a configuration of a lower portion of the molding device of FIG. 1, and FIG. 3 is a molding device of FIG. FIG. 4 is a cross-sectional view of the lower portion taken along the line AA, FIG. 4 is a cross-sectional view showing a state in which the molten resin is filled in the cavity of the mold, and FIG. 5 is a cross-sectional view showing a state in which the second receiving plate is opened. FIG. 6 is a sectional view showing a state where the screw core is loosened from the female screw portion of the molded product. FIG. 1 is a diagram showing a state in which the upper mold is slightly raised.

As shown in FIG. 1, the apparatus for molding a threaded part of this embodiment has a lower mold 1 and an upper mold 2,
A molded product 4 is formed by the cavity 3 formed between the two dies 1 and 2. The lower mold 1 is opposed to the upper mold 2 and has a mold plate 6 in which a stepped round hole 5 is formed, a first receiving plate 7 provided immediately below the mold plate 6, A second receiving plate 8 provided immediately below, a screw core 9 provided to be relatively movable in the opening and closing direction of the upper mold 2, that is, the vertical direction in FIG. 1, and a gear 10 for rotating the screw core 9 And a torque transmitting means 12 for transmitting the torque of the motor 11 shown in FIG. The upper mold 2 has a plurality of eject pins 13 for removing the molded product 4 from the upper mold 2 and an insertion hole 14 into which the upper part of the screw core 9 is inserted. The molded product 4 is formed, for example, in the shape of a rotating body, has a female screw portion 4a on the inner periphery, and has a non-illustrated detent rib extending vertically in FIG. 1 on the outer periphery.

The screw core 9 has an insertion hole 14 at the top.
And the lower portion is formed in the small diameter portion 5a of the round hole 5 and the first portion.
And a disc-shaped flange 16 inserted into the large-diameter portion 5b of the round hole 5. A male screw portion 17 corresponding to the female screw portion 4a of the molded product 4 is provided on the outer periphery of the flange portion 16. The rotating shaft 15 is formed with a pair of flat portions 18 facing each other and extending in parallel with the axial direction. Bearings 19 and 20 supporting the rotating shaft 15 are respectively provided with the template 6 and the first plate 6. It is fitted into the receiving plate 7.

As shown in FIG. 2, the gear 10 has an oval-shaped insertion hole 21 at the center, and the rotational force of the gear 10 is reduced by inserting the rotary shaft 15 into the insertion hole 21. The gear 10 is transmitted to the screw core 9 via the flat portion 18 and is relatively movable in the vertical direction in FIG. As shown in FIG. 3, the rotational force transmitting means 12 is provided on the template 6 so as to be movable, and is provided on the rack 22 which moves in the vertical direction in FIG. , The rack 2
2, a rotating shaft 24 rotatably supported by the template 6 and the first receiving plate 7,
An intermediate gear 25 which is connected to each other by 4 and rotates integrally;
26. The upper intermediate gear 25 is the rack 2
The lower intermediate gear 26 meshes with the gear 10.

In the molding method of this embodiment, first, as shown in FIG. 4, the lower mold 1 and the upper mold 2 are closed as a mold clamping step, and the lower end of the rotary shaft 15 of the screw core 9 is moved to the second position. The screw core 9 is raised to a predetermined position by being received by the receiving table 8a of the receiving plate 8. Next, as an injection step, a molten resin is injected into the cavity 3 between the molds 1 and 2, and the molten resin is cooled and solidified to obtain a molded product 4.
As shown in FIG. 5, as the primary mold opening process,
Is lowered to release the state of contact with the lower end of the rotating shaft 15. At this time, although the screw core 9 can be lowered, the screw core 9 is maintained at a predetermined position because the male screw portion 17 is screwed with the female screw portion 4a of the molded product 4. Then
As shown in FIG. 1, when the upper mold 2 is slightly raised in the secondary mold opening step (first state) , the molded product 4 is opened.
A clearance is formed around the female screw portion 4a of the molded product 4, and the screw core 9 rises from a predetermined position in a state of being screwed with the female screw portion 4a of the molded product 4. In this state, the torque transmitting means 1 is driven by driving the motor 11 as a screw core rotating step.
When the gear 10 is rotated via the gear 2, the screw core 9 rotates with the rotation of the gear 10, and the male screw portion 17 of the screw core 9 loosens from the female screw portion 4a. At this time, since the anti-rotation rib is provided on the outer periphery of the molded product 4, the molded product 4 is hard to rotate with respect to the upper mold 2.
Is reliably prevented. Thereafter, as shown in FIG. 6, the upper mold 2 is further raised in the third mold opening step (second state) , and the molded product 4 is removed from the upper mold 2 by the eject pin 13 in the ejecting step. It is supposed to.

In the embodiment configured as above, when the screw core 9 is rotated in the screw core rotating step, the female screw portion 4a
Is in a free state where it is not restricted by the wall of the template 6, that is, the rotational resistance is reduced by the elastic deformation of the female screw portion 4a to the outside, so that the driving force required for the rotation of the screw core 9 is reduced. As a result, the cost of the driving device including the motor 11 can be reduced.

[0015]

As described above, according to the present invention,
Driving force required for rotating the screw core provided in the mold can be reduced, and therefore, there is no need to increase the size of a driving device such as a motor for driving the screw core, thereby reducing costs. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of an apparatus for forming a threaded part according to the present invention.

FIG. 2 is a plan view showing a configuration of a lower portion of the molding device of FIG. 1;

FIG. 3 is a cross-sectional view taken along line AA of a lower portion of the molding apparatus of FIG. 2;

FIG. 4 is a sectional view showing a state in which a molten resin is filled in a cavity of a mold.

FIG. 5 is a cross-sectional view showing a state where a second receiving plate is lowered.

FIG. 6 is a cross-sectional view showing a state where a screw core is loosened from a female screw portion of a molded product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower mold 2 Upper mold 3 Cavity 4 Molded product 4a Female screw part 9 Screw core 10 Gear 11 Motor 12 Rotational force transmission means 17 Male screw part

Claims (2)

(57) [Claims] 1. A method of forming a threaded part having a female thread on an inner peripheral surface thereof, wherein a thread core having a male thread on an outer peripheral surface slides in an axial direction of the thread core.
A first mold freely provided and opposed to the first mold
Second and mold injecting a counter abutment allowed formed mold the molten resin into the cavity, after obtaining a molded article by cooling and solidifying the molten resin in the cavity of the screw
The core, the molded product and the second mold are integrated.
While maintaining the state, the opening of the screw core of the first and second molds in the axial direction is slightly performed to form a clearance around the female screw portion of the molded product,
In this state, the contact state between the second mold and the molded product is changed.
A method for forming a threaded part, comprising: rotating the screw core while maintaining the screw core to loosen the screw core from the female screw portion of the molded product . 2. A female screw portion on an inner peripheral surface.MoldingMolding
Used forHaving first and second molds,The first
Said in the moldOf molded productsFemale screwDepartmentMale thread corresponding to
Equipment for forming threaded parts with a threaded core
And saidFirst and second moldsIsFemale of the molded product
To obtain clearance around theScrew core
AxiallyA first mold opening state slightly separated from the first mold opening state;
Open the first mold in the direction to eject the part.
To the second mold opening state, which is larger than the
ComePossibleYes,On the first mold side,Turn the screw core
Motor to rollThe rotation of the motor on the screw core
Transmit forceTorque transmission meansAnd the first mold
Sliding support for supporting the screw core slidably in the axial direction
Holding means, the first and the first abutting counterparts
The molten resin is cooled and solidified in the cavity of the second mold.
The first and the first steps performed after the molded article is obtained
Moving the second mold to the first mold open state;Mold openingWhen
ToThe screw core, the molded product and the second mold;
Is maintained in an integrated state, and the molded article is
Clearance is formed around the internal thread
An apparatus for forming a threaded part.