JP2002067105A - Method and apparatus for separating multi-cavity plastic moldings - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method and an apparatus capable of simultaneously separating a plurality of plastic moldings from a molding finished product formed with the plastic molding via a gate part to a plurality of runners extended radially from a sprue without using a cutter. SOLUTION: The method for simultaneously separating the plurality of the plastic moldings comprises the steps of contacting an annular end face of an ultrasonic oscillation horn with the plurality of the runners of the molding finished product at equally separating positions from a center of the sprue, giving an ultrasonic oscillation to give substantially uniform oscillations to the plastic molding including the gate to thereby break the weakest gate, and almost simultaneously separating all the moldings on the one molding finished product. The apparatus for simultaneously separating the plurality of the plastic moldings is provided.

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 separating a multi-piece plastic molded product from a runner after completion of molding.

[0002]

2. Description of the Related Art As a molding method for simultaneously molding a large number of plastic molded products, a plurality of runners are projected in a radial direction from a central sprue portion, and a plastic portion is formed at the tip of the runner through a gate portion. A method for forming a molded article is known. In this multi-cavity molding method, after the molding is completed, the molded product taken out of the mold is in a state where the sprue, the runner, the gate, and the plastic molded product are connected.

Conventionally, in order to separate a plastic molded product from the finished molded product, a cutting tool (nipper, rotary blade, etc.) has been used to cut the gate portion of each plastic molded product. This cutting operation has to be performed for each plastic molded product, and the operation efficiency is extremely poor.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a separation method and apparatus capable of simultaneously and rapidly separating a multi-piece plastic molded article from a finished molded article without using a blade.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for separating (breaking) a plastic molded product by applying ultrasonic vibration to a molded product.
In order to simultaneously separate a plurality of plastic molded products, this is made by paying attention to the general shape of the molded product.
That is, the finished product is generally a sprue at the center,
A plurality of runners extending radially from the sprue, and a plastic molded product formed at an end of the runner at an equal distance from the sprue via a gate portion are provided, and the gate portion is the weakest ( Small cross-sectional area).

According to the present invention, which focuses on the shape of the finished product, in a method aspect, there is provided a step of preparing a cylindrical ultrasonic vibration horn having a hole at a central portion for allowing a sprue of the finished product to enter; Contacting the annular end surface of the ultrasonic vibration horn with a plurality of runners of a molded product having a sprue inserted into the hole at a position equidistant from the center of the sprue; and ultrasonically contacting the ultrasonic vibration horn. Vibrating the vicinity of the gate portion by applying vibration.

[0007] As described above, a plurality of runners of a molded product are
When the ultrasonic vibration horn is brought into contact with the annular end face of the ultrasonic vibration horn at an equidistant position from the center of the sprue and the ultrasonic vibration is applied, almost uniform vibration is applied to the plastic molded product including the gate portion, and as a result, the molding is completed. The weakest gate portion of the article breaks, and all of the plastic molded articles on one finished article can be separated almost simultaneously.

According to an aspect of the present invention, in a device aspect, a sprue at a center portion, a plurality of runners extending radially from the sprue, and a tip of the runner formed at a position equidistant from the sprue via a gate portion. An apparatus for separating a molded plastic article from a molded plastic article having a molded plastic article, comprising: a table on which the molded article is placed in contact with its runner; A cylindrical ultrasonic vibration horn having a hole at the center for allowing a sprue of the molded product to enter therethrough; the ultrasonic vibration horn and the table are relatively moved toward and away from the ultrasonic vibration horn; An advancing / retracting mechanism for clamping the plurality of runners between the annular end face and the table; and an ultrasonic vibration device for applying ultrasonic vibration to the ultrasonic vibration horn. It is a symptom.

The present invention can be applied irrespective of the type, shape, material, and the like of the plastic molded product. Particularly, the present invention was applied to a plastic lens, and a favorable result was obtained.

[0010]

1 and 2 show an embodiment of an apparatus for separating a multi-piece plastic molded product according to the present invention. The molded product 10 has a conical sprue 11 at the center, a plurality of runners 12 extending radially from the sprue 11 in the same plane orthogonal to the axis of the sprue 11, and a tip of each runner 12. Respectively,
And a plastic lens 14 connected via a gate 13. The sprue 11 has a downwardly extending sprue 11U extending downward from the runner 12 in FIG. In the illustrated example, four runners 12 are formed at 90 ° intervals, and two gate portions 13 and two plastic lenses 14 are formed at the tip of each runner 12. All the plastic lenses 14 are formed at the same distance from the center of the sprue 11, and the portion having the smallest cross-sectional area exists near the connection between the gate portion 13 and the plastic lens 14. A mold and a molding method for molding such a molded product 10 are well known.

The separating device (vibration breaking device) 20 has a fixed table 21 on which the molded product 10 is placed. The fixed table 21 has a mounting plate 22 made of an elastic material such as rubber on the upper end surface thereof.
Is formed with a relief hole 23 at the center thereof for inserting the downward extension sprue 11U of the molded product 10. The lower extension sprue 11U of the molded product 10 is
, The runner 12 comes into contact with and is mounted on the mounting plate 22, and the sprue 11 extends in the vertical direction.

On the fixed table 21, an ultrasonic vibration horn 25 having a cylindrical shape with a bottom and having a hole 24 at the center for allowing the sprue 11 of the molded product 10 to enter is located. The ultrasonic vibration horn 25 is connected to an elevating mechanism 26 and an ultrasonic vibration device 27, and is moved up and down on the fixed table 21 by the elevating mechanism 26, and ultrasonic vibration is given by the ultrasonic vibration device 27. The amplitude and frequency of the ultrasonic vibration by the ultrasonic vibration device 27 are determined by the ultrasonic vibration control device 2.
8. The center of the sprue entry hole 24 of the ultrasonic vibration horn 25 and the escape hole 2 of the fixed table 21
The centers of 3 are coincident. The lower end surface of the ultrasonic vibration horn 25 forms an annular contact surface 25t formed of a plane orthogonal to the axis of the ultrasonic vibration horn 25.

The present apparatus having the above configuration is used as follows. The molded product 10 is placed on the fixed table 21 in a state where the ultrasonic vibration horn 25 is raised by the lifting mechanism 26. At this time, the lower extension sprue 11U is positioned at the center of the escape hole 23, and the runner 12 is brought into contact with the mounting plate 22. The fixed table 21 has a downwardly extending sprue 11
A guide mechanism for aligning U with the center of the escape hole 23 can be provided. In this setting state, the ultrasonic vibration horn 25 is lowered by the lifting mechanism 26, and the runner 12 is clamped between the contact surface 25t and the mounting plate 22.
Then, the contact surface 25t comes into contact with the plurality of runners 12 at a position equidistant from the center of the sprue 11.

Next, ultrasonic vibration is applied to the ultrasonic vibration horn 25 through the ultrasonic vibration device 27. Then, the entire molded article 10 in which the runner 12 is in contact with the contact surface 25t vibrates. In particular, the plurality of runners 12 extending in the radial direction have the tip portions centered on the portion held by the contact surface 25t. Vibration with larger amplitude is given to the side. as a result,
In the vicinity of the gate section 13 having the smallest sectional area, the gate section 1
3 is broken (broken). Since the plurality of runners 12 are in contact with the contact surface 25t at the same distance from the sprue 11, all of the plastic lenses 14 are almost simultaneously separated from the molded product 10. Various conditions of the ultrasonic vibration by the ultrasonic vibration device 27 are set by the ultrasonic vibration control device 28 so that the above operation can be obtained. It is preferable that the vibration by the ultrasonic vibration device 27 is such that a timer provides vibration characteristics sufficient for separating the plastic lens 14 according to the properties of the molded product 10 for a predetermined time. When the separation of the plastic lens 14 from the molded product 10 is completed, the vibration by the ultrasonic vibration device 27 is stopped, and the ultrasonic vibration horn 25 is
To prepare for the next work.

FIG. 3 shows an example of the shape of the runner 12, the gate portion 13, and the plastic lens 14. In this example, the thickness of the gate portion 13 is monotonously reduced toward the plastic lens 14, and a thin annular portion 14 a is formed at an end of the plastic lens 14. That is, the portion having the smallest cross-sectional area exists in a portion slightly inside the plastic lens 14, and as a result, the fractured surface 16 occurs in a portion slightly inside the plastic lens 14. Therefore, by making the shape of the plastic lens 14 slightly larger than the required shape (by setting the fracture surface 16 generated in the plastic lens 14 so as not to affect the optical performance), the burr treatment is not required. There are advantages.

FIG. 4 shows another example of the shape of the runner 12, the gate 13, and the plastic lens 14. This example is an example in which a fixed cross-section 13c is formed at the tip of the gate 13 on the plastic lens 14 side. In the case of this shape example, the fracture surface 16 is most likely to occur in the constant cross section 13c. Therefore, in the case of the shape shown in FIG. 4, burrs may remain on the plastic lens 14 separated from the molded product 10, but fine burrs do not matter in the plastic lens or other plastic molded products. Even if there is a case, and even if a deburring operation is required, according to the present invention, compared with the conventional separation method using a blade, a multi-piece plastic lens 14 is required.
Can be separated at the same time.

The molded product 10 of the above embodiment is an example, and the number of runners 12 extending from the sprue 11 in the radial direction and the number and shape of the plastic lens 14 formed at the tip of the runner 12 are not limited. Absent. The present invention is also applicable to a mode in which the plastic lenses 14 are present at different equidistant distances from the center of the sprue 11 (that is, a mode in which the plastic lenses 14 are present on concentric circles having different diameters). In the case of this mode, the mode of the ultrasonic vibration applied to the ultrasonic vibration horn 25 can be changed in a plurality of stages.

[0018]

According to the present invention, a plurality of plastic molded articles can be simultaneously separated from a finished molded article having a multi-piece plastic molded article without using a blade.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a separating device for a multi-piece plastic molded product according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a partially enlarged view of a molded product.

FIG. 4 is a partially enlarged view showing another example of the shape of a molded product.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 Molded product 11 Sprue 12 Runner 13 Gate portion 14 Plastic lens (plastic molded product) 16 Breaking surface 20 Separation device 21 Fixed table 22 Mounting plate 23 Escape hole 24 Sprue entry hole 25 Ultrasonic vibration horn 25t Contact surface 26 Elevating mechanism 27 Ultrasonic vibration device 28 Ultrasonic vibration control device

Claims (4)

[Claims] 1. A sprue at a central portion, a plurality of runners extending radially from the sprue, and a plastic molded product formed at an end of the runner at a position equidistant from the sprue via a gate portion. Providing a cylindrical ultrasonic vibration horn having a hole at a center portion thereof for allowing a sprue of the molded product to enter; a method of separating the plastic molded product from the molded product; Bringing the annular end faces of the ultrasonic vibration horn into contact with a plurality of runners of the molded product having sprues inserted therein at an equidistant position from the center of the sprue; and applying ultrasonic vibration to the ultrasonic vibration horn. And breaking the vicinity of the gate portion. 2. The method according to claim 1, wherein the plastic molded product is a plastic lens. 3. A sprue at a central portion, a plurality of runners extending radially from the sprue, and a plastic molded product formed at an end of the runner at an equal distance from the sprue via a gate portion. An apparatus for separating the molded plastic article from the molded molded article having: a table on which the molded article is placed with the runner in contact therewith;
A cylindrical ultrasonic vibrating horn having a hole at the center for allowing the sprue of the molded product to enter; a cylindrical ultrasonic vibrating horn and a table which are relatively moved toward and away from the annular vibrating horn; An apparatus for separating a multi-piece plastic molded product, comprising: an advance / retreat mechanism for holding the plurality of runners between the table and a table; and an ultrasonic vibration device for applying ultrasonic vibration to the ultrasonic vibration horn. . 4. The separation device according to claim 3, wherein the plastic molded product is a plastic lens.