JPS60129217A - Method and apparatus for preparing concave lens - Google Patents

Abstract

PURPOSE:To mold a high-grade resin concave lens free from a weld line by injecting molten resin material into a mold moving the injection hole continuously along the peripheral direction. CONSTITUTION:A movable slider 4 is provided on the runner between the mold section 8 and the gate 7. Thereby, molten resin material supplied from the gate 7 is injected into the mold section 8 moving the injection hole 13 at the end of the injection slider 4 continuously along the peripheral direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical field of the invention The present invention relates to a method and apparatus for manufacturing a concave lens used, for example, as a lens for near glasses or a large lens for a video projector. This article relates to a method and apparatus for manufacturing concave lenses suitable for mass production.

(B) Background of the Invention In recent years, methods for manufacturing concave lenses such as the example described above have been developed.
As demand tends to increase, mass production is desired, and for this purpose, it is required to employ molding means suitable for human production.

However, unlike convex lenses, the molding method for concave lenses is different from that of convex lenses, as is well known, because the center part of the concave lens is thin, so there is a time difference in the flow (flow phenomenon) of the molten resin material injected into the mold. Solidification streaks (weld lines) were generated in the radial direction of the concave lens in the mold due to the difference in solidification of the resin raw materials, and the lens could not be used as a concave lens. For this reason, it is currently impossible to manufacture concave lenses using resin raw materials, resulting in low production efficiency.

(c) Purpose of the Invention Therefore, the object of the present invention is to provide a method for manufacturing a concave lens and an apparatus therefor, which are capable of molding a concave lens using a resin raw material.

(D) Summary of the Invention The present invention provides a method for manufacturing a concave lens that makes it possible to manufacture a concave lens without weld lines by injecting a resin raw material to be injected into a mold while continuously moving it in the circumferential direction. It is characterized by being a device.

(E) Effects of the Invention According to this invention, since the melted resin raw material for the concave lens is injected while being displaced in the circumferential direction inside the mold part, this injection flow is directed from the circumferential direction to the central part and each part in the circumferential direction. As a result, the solidification of the resin raw material is uniformly performed in the circumferential direction within the mold section. Therefore, the relatively slow solidifying part does not concentrate in the center of the mold part, and even if resin raw materials are used as the material for concave lenses, concave lenses can be molded that completely eliminate the occurrence of weld lines due to differences in solidification. can do. Therefore, a molding method such as injection molding suitable for mass production can be easily adopted.

(f) Examples of the invention An embodiment of the present invention will be described in detail below based on the drawings.

The drawing shows a concave lens manufacturing device using injection molding.
In FIGS. 1 and 2, this apparatus 1 is comprised of a raw material injection device @2, a mold 3, an injection slider 4, and a reciprocating drive device 5 thereof.

The above-mentioned raw material injection device 2 melts methacrylic resin, polycarbonate resin, and scalol resin, and then performs an injection operation using the injection nozzle of this device against the upper surface of the sprue of the upper mold, which will be described later.

The above-mentioned mold 3 is composed of an upper mold 3a in the shape of a rectangular plate and a lower mold 3b in the same shape, which face each other vertically, of which the upper mold 3a
A lower groove for injecting the melted concave lens resin raw material 6 is vertically formed in the center of the upper surface, and one side 8a, 8a of the mold part 8.8 for the concave lens is formed in a pair on both sides of the lower surface. .

In addition, the lower mold 3b has mold portions 8.8 of concave lenses formed on both sides thereof in the same manner as the mold portions 8.8, which correspond to the above-mentioned one surfaces 8a, 8a. In order to guide the flow in the opposite directions (
A first runner 9.9 that branches off in the vertical direction in the figure, and a second runner 10.10 that communicates with the first runners 9 and 9 in a perpendicular direction (horizontal direction in the figure) are carved. It is set up.

The above-mentioned second hot water drain 10 has a groove-shaped cross section and is carved in an arc shape, and the inner end side of the second hot water drain 10 is connected to the radial outer circumference of the mold part 8 inside the mold. The outer end side is opened to communicate with the outside of the mold, and an injection slider 4 for performing injection operation by displacing the injection position from this frontage surface is inserted so as to be freely forward and backward.

As shown in FIG. 3, the above-mentioned injection slider 4 is removable through an arch-shaped upper shaft body 11 and a lower shaft body 12 having the same curvature as the arc shape of the above-mentioned second yuton 10. It is formed into a long shaft with a hollow rectangular cross section, and an injection port 13 for raw material injection is opened at the inner end of the long shaft, and one side facing the first lake path 9 in the longitudinal direction In this case, opening windows 14 for raw material distribution whose movement length in the circumferential direction corresponds to, for example, the radial length of a concave lens are arranged in n stages corresponding to the forward and backward movement m of the shaft body. In addition, the reason for omitting these upper and lower shaft bodies 11 and 12 is as follows.
This is to facilitate the removal action of the melted resin raw material 6 after injection and solidification. 15° and 16 are locking portions for engaging the shaft body.

In order to insert the inner end of the injection slider 4 into the mold part 8 so that it can move forward and backward, a forward and backward drive device 5 such as a hydraulic cylinder is connected to the outer end of the injection slider 4. The injection slider 4 is moved forward and backward. 17. 17 is a connection slider, 18 is a connection rod, 19 is a continuous rod, 20 is a mold base, and 21 is a drive stand.

The concave lens manufacturing apparatus configured in this way has the first
As shown in the figure and FIG. 2, the forward/backward drive device 5 is operated backward to position the inner end of the injection slider 4 at the center of the outer periphery of the mold section 8, and in this state, the material injection device 2 is While injecting the melted resin raw material from the lower groove, the advancing/retracting drive device 5 is operated forward to move the injection slider 4 backward at a constant speed. The inner end of the injection slider 4 is the mold part 8.
When it reaches the circumferential surface, the backward movement is stopped.

As a result, the resin raw material 6 injected from the hot water lower is injected into the injection slider 4.4 from the first runners 9, 9, and then from the inner end injection port 13 of these injection sliders 4, 4 into the mold part. Injected into 8,8.

Then, inside the mold part 8, the melted resin flows all at once in the circumferential direction, and as shown in FIGS. 4 and 5,
When the injection slider 4 reaches a predetermined retracted position, the melted resin raw materials 6 are spread throughout the mold section 8, and the resin raw materials 6 begin to uniformly solidify as a whole. Then, by removing the upper mold 3a after a certain period of time and taking out the solidified resin raw material, a desired concave lens without weld lines can be obtained.

(卜) Example of the Haku Other embodiments of the invention will be described below.

6 to 9 show an apparatus 31 for manufacturing concave lenses using injection molding. A linear injection slider 34 is inserted into a linear second runner 40 parallel to the side surface of the mold 33 so as to be freely advanced and retracted, and the resin raw material 36 is poured into the mold from the injection slider 34. The inner end portion of the injection slider 34 is disposed closer to the outer circumferential side of the mold portion 38 so that the injection slider 34 flows in the circumferential direction of the portion 38 .

Further, an advance/retreat drive device 135 such as a hydraulic cylinder is connected to the outer end of the injection slider 34, and the injection slider 34 is advanced or retreated by this driving operation.

The concave lens manufacturing apparatus configured in this way has a sixth
As not shown in the figures and FIG. While injecting the melted resin raw material from the sprue 37 through the sprue 37, the advancing/retracting drive unit @35 is operated backward, and the injection slider 34
to retreat. Then, when the inner end of the injection slider 34 reaches the circumferential surface of the mold section 38, the retracting operation is stopped.

As a result, the resin raw material 36 injected from the sprue 37 is injected into the injection sliders 34.34 from the 113i39, 39, and then into the mold portions 38, 38 from the inner ends of these injection sliders 34.34. Ru.

Then, within the mold section 38, the melted resin naturally flows from the center to the outer periphery, and as shown in FIGS. 8 and 9, the injection slider 34 reaches a predetermined retracted position. At this point, the melted resin raw materials are spread throughout the inside of the mold 38, and the entire raw materials begin to solidify uniformly. Then, by removing the upper mold after a certain period of time and taking out the solidified resin raw material, a desired concave lens without weld lines can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view showing the state in which the lower mold of the concave lens manufacturing apparatus is used. FIG. 2 is a vertical sectional view of the main part of the device. FIG. 3 is an enlarged perspective view, partially cut away, of the injection slider of the device. FIG. 4 is a plan view of the lower mold showing how the device is used. FIG. 5 is a longitudinal cross-sectional view of the main part showing the usage state of the device. 6 to 9 show other embodiments of the present invention, and FIG. 6 is a plan view showing the state in which the lower mold of the concave lens manufacturing apparatus is used. FIG. 7 is a vertical sectional view of the main part of the device. FIG. 8 is a plan view of the lower mold showing how the device is used. FIG. 9 is a longitudinal cross-sectional view of the main part showing the device in use. 1.31... Concave lens manufacturing device 3.33... Mold 4.34... Injection slider 5.35... Advance/retreat drive device 8.38... Molding mold section 8b Fig. 2 Fig. 3 Figure 4 1 Figure 5 Figure 6 A Figure 7 1

Claims (1)

[Scope of Claims] 1. A method for manufacturing a concave lens, which comprises injecting and solidifying a melted resin raw material for a concave lens into a pair of opposing molds each having a concave lens mold section therein, and molding the resin material, comprising: A method for manufacturing a concave lens, comprising injecting a melted resin raw material for a concave lens into a mold part of the concave lens while being displaced in the circumferential direction within the mold part. 2. A pair of opposing molds each having a concave lens molding part therein is provided, and the communication direction of the tunnel connecting the molding part of the mold and the sprue formed in the mold is set as above. The runner is formed in the same direction as the radial direction of the mold part, and the runner is continuously displaced along the circumferential direction of the mold part corresponding to the thick part of the concave lens via an advance/retreat drive device. A concave lens manufacturing apparatus 0 characterized in that an injection slider for pouring and operating the resin raw material for concave lenses is provided.