JPS59131429A - Release apparatus of mold for molding plastics - Google Patents

Abstract

PURPOSE:To make it possible to easily release a molded product without deteriorating the optical characteristics of a lens, by providing such a mechanism that the lens is released from a mold cavity surface in a mold and thereafter pushed out of the mold. CONSTITUTION:When a mold opening signal 18 is inputted to a control part 17, a slide block 10 is retracted by a hydraulic cylinder 11 and a movable mold insert top 4 is downwardly slid in a movable mold 2 while a lens 9 is released from the movable mold insert top 4 to remain in the taper part of an inlay ring 8. When the moving amount of the slide block 10 becomes equal to a predetermined value by the signal detected by a displacement sensor 16, the slide block 10 advances while the movable mold insert top 4 is pushed up. When the movable mold insert top 4 is returned to the position prior to mold opening, the slide block 10 and the movable mold insert top 4 are pushed up by a push-up plate 9 to push the lens 19 out of the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold release device that is attached to an injection mold or a hot compression mold for optical components such as plastic lenses, and more particularly, to a mold release device that can effectively remove plastic lenses from the mold surface. The 0 plastic lens is manufactured by injection molding or hot compression molding, taking into consideration its optical required characteristics and mass production. As shown in Fig. 1, a conventional molding die used for molding processing includes a fixed die piece 3 for shaping the lens surface, a movable die piece 4, a fixed die piece 1 for holding these pieces, and a movable piece. Composed of type 2.

In the injection molding process, molten resin is injected into a cavity 5 formed by a fixed mold insert piece 3 and a movable mold insert piece 4 at high speed and high pressure, and is cooled and shaped by heat exchange with the mold. . In addition, in the heat compression processing, a so-called lens blank roughly processed into an approximate shape of the lens is put into the cavity 5,
The lens blank surface is heated and compressed.

Thereafter, the lens surface is cooled by heat exchange with the mold, and the movable mold insert piece 4 is slid as shown in FIG.
9 is taken out of the mold, and in either processing method, a large processing pressure is applied to the lens surface during the injection process or the compression process in order to transfer the mold shape onto the lens surface with high precision. As a result, the lens 19 and the movable inserting piece 4 come into close contact with each other with a very large force, making it difficult to separate them. In order to release the lens 19 that is in close contact with the movable insert piece 4, conventional methods include applying impact force to the edge of the lens 19, or sufficiently cooling the movable mold insert piece 4 to separate the mold steel and plastic. Methods that utilize differences in coefficients of thermal expansion have been used, but these methods have problems such as deterioration of the precision of the lens surface shape, scratches on the lens surface, and lengthening of the molding cycle.

As a countermeasure against these problems, as shown in FIG.
A method is adopted in which the collar portion 6 is pushed out by a sleeve 7 that is slidable on the outer peripheral portion of the movable inserting piece 4. Although this method can solve the problem that occurs during demolding, it is necessary to post-finish the buckwheat portion 6. Brim part 6
During post-processing, new technical problems have arisen, such as interference with the optical axis and adhesion of chips due to static electricity, and no fundamental solution has been reached.

OBJECTS OF THE INVENTION An object of the present invention is to provide a mold release device for a plastic mold, which eliminates the drawbacks of the prior art described above and can easily release a molded product without deteriorating the optical characteristics of a lens. It is about providing the following.

In order to achieve the above object, the molding die of the present invention is characterized by having a mechanism that releases the lens from the mold cavity surface within the mold and then pushes the lens out of the mold.

EMBODIMENTS OF THE INVENTION AND EFFECTS OF THE INVENTION The mold release device of the present invention will be described in detail below with reference to the drawings. Fourth
The figure is an explanatory view showing one embodiment of a molding die having a mold release device of the present invention. In the same figure, the fixed mold 1 incorporates a fixed insert piece 3 that shapes the lens surface, and the movable mold 2 includes a movable insert piece 4 that shapes the lens surface, and a taper is provided on the inner diameter side. Fitting ring 8 that holds the lens side surface with the tapered part
, a wedge-shaped slide block 10 connected to the movable mold entry piece 4, an extrusion plate 9 that pushes up the movable mold entry piece 4 and the slide block 10 when taking out the molded product, and a slide block fixed to the extrusion plate 9 via a piston 12. A hydraulic cylinder 11 that moves the slide block 10 forward and backward on the push-out plate 9, and a displacement sensor 16 that is fixed to the push-out plate 9 and detects the position of the slide block 10 are incorporated. The movable entry piece 4 and the slide block are connected by a slidable dovetail groove as shown in FIG. 5, which is a cross-sectional view taken along line A-A' in FIG. .

Accordingly, the movable entering piece 4 moves on the slide block 9.

It moves and moves up and down inside the movable mold 2. Also, outside the mold, a hydraulic pump 14, a tank 15, a directional control valve 13 that controls the direction of hydraulic oil supplied from the hydraulic pump to the hydraulic cylinder 11, a signal from a displacement sensor 16, and a mold opening signal 18 are input to the directional control valve. 13 is provided with a control section 17 that outputs a control signal. Next, we will discuss the operating principle of the mold when releasing the molded product.
This will be explained in detail with reference to FIGS. 6 and 7. The lens 19 remains in the movable mold 2 when the molding die is in the state shown in FIG. 4 immediately before completion of molding, that is, just before the mold is opened. The mold opening signal 18 is input to the control section 17, a control signal is transmitted from the control section 17 to the directional control valve 13, and hydraulic oil is supplied to the rod side in the hydraulic cylinder 11 via the directional control valve 13. Accordingly, the slide block 10 retreats, and the movable mold insert piece 4 slides downward inside the movable mold 2. At this time, the lens 19 that is tightly attached to the capy surface of the movable mold inserting piece 4 is fixed to the 717 part of the fitting ring 8, is released from the movable mold inserting piece 4, and remains on the tapered part of the fitting ring 8, The result is as shown in FIG. Then, it is confirmed that the lens 19 has been released from the movable mold inserting piece 4 by the amount of movement of the slide block 10. That is, displacement sensor 1
The control unit 17 performs calculations based on the signal detected at step 6, and when the amount of movement of the slide block 10 becomes equal to a predetermined value, the control unit 17 transmits a control signal to the directional control valve 13, and the hydraulic oil is supplied. It is supplied to the head side inside the hydraulic cylinder 11.

Accordingly, the slide block 10° moves forward and the movable inserting piece 4 is pushed up. The position of the slide block is detected by the displacement sensor 16, and when the movable mold entry piece 4 returns to the position before mold opening, a signal is sent from the control section 17 to the direction control valve 13.
The supply of hydraulic oil to the hydraulic cylinder 11 is stopped. Thereafter, the slide block 10 and the movable inserting piece 4 are pushed up by the pushing plate 9, and the lens is assembled as shown in FIG.

19 is extruded out of the mold. Since the lens 19 and the movable mold insert 4 have already been released from the mold, they can be easily taken out.

As a result, a lens with good precision could be obtained easily and without any post-processing.

Effects of the Invention As described above, according to the present invention, it is possible to easily release the lens from the mold, and the amount of deformation of the lens shape during release is smaller than in the conventional method of releasing the lens by applying an impact force. We were able to improve the shape accuracy by about twice. Furthermore, the molding cycle could be shortened to about 3 compared to a method in which cooling is performed until the mold becomes easy to release due to the difference in thermal expansion coefficient between the mold and the lens.

On the other hand, compared to the method of providing a collar on the outer periphery and extruding the collar, the time required for post-processing of the collar can be reduced.
It is possible to prevent chips and the like from adhering to the lens.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a conventional molding die having a mechanism for extruding lenses through the entire mold cavity surface, and Fig. 2 is an explanatory diagram showing an example of a conventional molding die having a mechanism for extruding a lens through the entire mold cavity surface. FIG. 3 is an explanatory diagram showing an example of a conventional molding die having a mechanism for extruding the outer circumference of the lens, FIG. 4 is an explanatory diagram showing an embodiment of the present invention, and FIG. A-A' sectional view,
6 and 7 are explanatory diagrams showing the operation of the mold shown in FIG. 4, respectively. Description of symbols 1...Fixed type, 2...Movable type, 3...Fixed i-type piece, 4...Movable type piece, 5...・Cavity, 7...
Sleeve, 8...Inset ring, 9...
...Extrusion plate, 10...Slide block, 11
...Hydraulic cylinder, 19...Lens, size 2, size 3, size 6

Claims (1)

[Claims] 1) A fixed inserting piece member that shapes the lens surface, a movable inserting member that also shapes the lens surface, and a fitting ring that is tapered on the inner diameter side and holds the lens side surface with the tapered part of the reel. A plastic lens molding mold comprising: a driving means for driving the movable inserting member; and a displacement sensor for detecting the amount of movement of the driven inserting member, and monitoring the output of the sensor. and a control section for controlling the drive means, the control section being held on the inner tapered portion of the fitting ring member by the drive means in synchronization with a mold opening signal from the molding machine. The movable inserting piece member is moved in a direction away from the lens, whereby the inserting piece member and the lens surface are released from the mold within the mold, and the release is detected by the output of the displacement sensor. A mold release device for a plastic mold, characterized in that the lens is extruded along the tapered portion.