JPH0651296B2 - Positioning method for molding plastic lens - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for positioning a pair of molds used when molding a plastic lens.

[Prior Art] Conventionally, there is known a casting method in which a plastic material is filled in a cavity formed between a pair of molds facing each other at a predetermined interval to mold a plastic lens. In this cast molding, in order to mold a plastic lens with high accuracy, how accurately the pair of molds can be set at predetermined positions becomes a problem.

As a method of setting the molds, a pair of molds are positioned by sandwiching a ring-shaped spacer between the molds, then the spacers are removed by leaving a space between the molds, and then the molds are returned to their original positions again to surround the two molds. A method is known in which a cavity is formed by closely adhering an adhesive tape that extends between molds (Japanese Patent Publication No. 60-2).
9333 publication).

According to this method, since the parallelism and the mold interval of the two molds can be determined to a predetermined state by only sandwiching the spacer between the two molds, it is possible to easily perform highly accurate positioning.

[Problems to be Solved by the Invention] However, in the above method, it is necessary to perform temporary assembly using a spacer, remove the spacer, and then return the mold to the positional relationship during temporary assembly with high accuracy. There is a problem that the positioning work of 2 is troublesome and the work efficiency is poor.

Further, it is necessary to have a large number of spacers having different sizes corresponding to various lenses, which causes a problem that the manufacturing and management of the spacers become enormous.

Furthermore, after the temporary assembly, the spacers must be removed, but since they are ring-shaped spacers, one of the peripheral walls of the spacers crosses the cavity between the molds to be formed later during the removal. There is also a problem that foreign matter may be mixed in between. If foreign matter is mixed in, the quality of the lens as a product will be impaired.

The present invention provides a pair of opposed molds without spacers in order to solve the above-mentioned problems of temporary assembly work, manufacturing and management of spacers, and lens quality problems in the conventional method using spacers. It is an object of the present invention to provide a method capable of accurately positioning a workpiece in a predetermined state.

[Means for Solving the Problems] A method for positioning a plastic lens molding mold according to the present invention, which is directed to this object, positions a pair of molds in a predetermined state in order to mold a plastic lens between a pair of opposed molds. In the method described above, first, the center positions of the pair of molds are aligned by restraining the positions of the pair of molds from the peripheral edge side, and the pair of molds are held on both sides by a pair of parallel holders. Then, the position of the center part of the mold using surface of the first mold of the pair of molds is measured, and the position of the second mold in the optical axis direction to be set with respect to the measured position is calculated. , Controlling the movement of the holder holding the second mold in the optical axis direction so that the second mold comes to the calculated position. Method.

The measurement of the position of the central portion of the mold using surface of the first mold is performed with respect to a certain reference surface of the device,
The calculation of the position of the second mold in the optical axis direction to be set and the movement control are also performed on the reference surface.

[Operation] In such a method, the pair of molds are positionally constrained from the peripheral side of the molds so that the center positions of the molds are aligned with each other, and in that state, the molds are held from both sides by the holders having parallelism. Therefore, the pair of molds are first set in a state in which the opposing surfaces are in a predetermined parallel state and the optical axes match each other. Next, the thickness of the lens, that is, the distance between the molds is determined. The position of the central part of the first mold is measured, and the position of the second mold in the optical axis direction to be set in a state including the known shape of the second mold with respect to the measured position. Is calculated. Then, the holder holding the second mold is controlled to move in the optical axis direction based on the above calculation result. This movement is performed while maintaining parallelism between the molds and matching of the optical axes. By the movement control, the pair of molds is finally determined in a predetermined positional relationship.

Therefore, it is possible to perform the predetermined positioning of the mold without using the ring-shaped spacer as in the conventional case, the temporary assembly work of the mold using the spacer is eliminated, and the positioning work between the molds can be performed substantially once. The efficiency can be improved and the positioning accuracy can be improved.

Further, since the position of the mold can be set to an arbitrary set value based on the calculated value, the problems of manufacturing and managing a large number of spacers, which have been conventionally problems, are completely eliminated.

Furthermore, the pair of molds are centered by the position restraint from the peripheral portion, and after they are aligned, the position restraint jig can be opened in the mold radial direction and does not have to be passed between the molds, so foreign matter is mixed between the molds. The chances are greatly reduced, and the probability of foreign matter entering the molded lens is also reduced.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show an apparatus for carrying out a method for positioning a plastic lens molding mold according to an embodiment of the present invention. In the figure, 1 and 2 show a pair of molds for molding a plastic lens, and inside a cavity formed between a lower mold 1 as a first mold and an upper mold 2 as a second mold, which are opposed to each other. The lens is molded by filling the plastic raw material with.

Reference numerals 3 and 4 denote a lower mold centripetal device and an upper mold centripetal device that align the centers of the molds 1 and 2 by restraining the positions of the molds 1 and 2 from the peripheral portions thereof. The lower mold centripetal device 3 includes a chuck 5 that can slide horizontally on the reference plane A and a cylinder 6 that moves the chuck 5 in the radial direction of the mold 1. The upper mold centripetal device 4 is mounted on the upper surface of the chuck 5. It is composed of a chuck 7 that is slidable in the horizontal direction on the formed reference plane B, and a cylinder 8 that moves the chuck 7 in the radial direction of the mold 2.

Cups 9 and 1 capable of holding the molds 1 and 2 and having holding surfaces facing each other in parallel are provided on the upper and lower sides of the upper and lower molds 1 and 2.
0 is provided. The cups 9 and 10 are suction cups in this embodiment, and are configured to be rotationally drivable. The upper cup 10 is supported movably up and down via a rod 11, and is moved by a cylinder 12 when making a large up and down movement, and by a pulse motor 14 through a screw portion 13 when making a small up and down movement. Position control is possible.

The pulse motor 14 is connected to the data processing device 15 and is operated based on a signal from the data processing device 15. The data processing device 15 is connected to the data input device 16, and the data input device 16 and the position measuring instrument 17 are connected.
The signal sent to the pulse motor 14 is arithmetically processed based on the signal from. The position measuring device 17 can measure the position of the mold in a non-contact manner. In this embodiment, the position measuring device 17 is composed of an optical sensor type image sensor capable of detecting the position of the top surface of the lower mold 1. In addition, 18 is the data processing device 1
5 is a data output device connected to 5, and if not provided, it is possible to display or print out the mold set performance table of the molds 1 and 2 if provided.

The method of the present invention is carried out as follows using the embodiment apparatus configured as described above.

First, the lower mold 1 is placed on the suction cup 9,
The lower mold chuck 5 is closed. In this state, the position of the lower mold 1 is restricted from the peripheral portion and the cup 9
The optical axis 19 of the mold 1 is aligned with the optical axis 19 of the mold 1, and the lower mold 1 held on the upper holding surface of the horizontal cup 9 is also kept horizontal. Further, since the chuck 5 is simply slid on the horizontal reference plane A, the upper surface of the chuck 5 is located above the reference plane A by a preset thickness of the chuck 5 and is a constant horizontal reference plane. Configure B.

Next, the upper mold 2 is placed on the chuck 5. Since the upper surface of the chuck 5 constitutes a horizontal reference plane B, the upper mold 2 is kept on the chuck 5 in a horizontal state simply by being placed on the chuck 5. After that, the chuck 7 for the upper mold 2 is closed, and the position of the upper mold 2 is mechanically constrained from the peripheral edge so that the central position of the upper mold 2 coincides with the central position of the lower mold 1, that is, the optical axes thereof match each other. After that, the cup 10 for adsorbing the upper mold 2 is lowered, and the upper mold 2 receives the cup 10
Held in.

Next, in this state or with the chuck 7 opened and the upper mold 2 held in the cup 10 and slightly raised, the position of the upper surface of the center of the lower mold 1, that is, the position of the top surface of the lower mold 1 is measured. Measured by the instrument 17. The measurement signal is sent to the data processing device 15, and the data processing device 15
The vertical position of the upper mold 2 with respect to the lower mold 1 is calculated together with the signal from the data input device 16. This calculation is performed by the distance between the center portions of the molds 1 and 2 or the distance between the peripheral portions so that the center portion thickness or the peripheral thickness of the lens molded between the molds has a predetermined thickness. More specifically, for example, as shown in FIG. 3, the top surface position of the lower mold 1 is measured as the height with respect to the reference surface B, and the height of the upper mold 2 to be set is the upper mold with respect to the reference surface B. 2 is calculated as the position of the lower surface of the peripheral portion. That is, the top surface position C of the lower mold 1
The lower surface position D of the peripheral portion of the upper mold 2 is used as a reference surface for setting the mold gap. Of course, in the calculation, the data of the R shapes of the upper and lower molds 1 and 2 which are known in advance are input and used.

Next, a signal is sent from the data processing device 15 to the pulse motor 14 based on the calculated value, the pulse motor 14 is rotated by a predetermined number of pulses, and the upper mold 2 is vertically moved by a predetermined amount via the screw portion 13 and the rod 11. The movement is controlled in the direction, that is, the direction along the optical axis 19. The mold holding surfaces of the opposing cups 9 and 10 are parallel to each other and are kept in parallel during the movement control, and the positions are set while keeping the optical axes of the molds 1 and 2 aligned. The upper mold 2 is set to have a parallelism with the lower mold 1, a central position, and a predetermined positional relationship.

In this way, the pair of molds can be positioned without using a spacer, and by using the highly accurate position measuring device 17 and the pulse motor 14, highly accurate positioning can be performed at an arbitrary mold interval (lens thickness). Will be possible.

Although the pulse motor 14 is used in this embodiment, any other suitable high-precision movement control means may be used, and the position measuring device 17 may be any device as long as non-contact measurement is possible. You can

[Effects of the Invention] As described above, according to the present invention, the following various effects can be obtained.

First, since it is not necessary to use the conventional spacers, it is not necessary to manufacture and manage the spacers, and the mold interval can be set to an arbitrary value, so that it is possible to easily cope with various lens specifications.

In addition, the positioning of the mold interval need only be performed by actually positioning one of the molds only once, which improves working efficiency and substantially eliminates an error element during positioning work. Therefore, the mold positioning accuracy can be improved by using the high-precision movement control means and the high-precision position measuring device as shown in the embodiment apparatus.

Also, since the temporary mold assembly work using spacers is eliminated,
Moreover, since the operation according to the present invention can be almost completely automated, the manual work can be facilitated and the amount of processing can be increased accordingly.

Further, the position of the mold is restrained from the peripheral portion during positioning, but the position restraint tool does not cross between the molds, so that the chance of foreign matter mixing between the molds is greatly reduced,
A clean lens molding cavity is formed between the molds. Therefore, it is possible to improve the quality of the cast plastic lens.

[Brief description of drawings]

1 is a schematic configuration diagram of a positioning device for carrying out a method of positioning a plastic lens molding mold according to an embodiment of the present invention, FIG. 2 is an enlarged partial sectional view of the device of FIG. 1, and FIG. FIG. 4 is a schematic partial configuration diagram showing the relationship between the mold and the reference surface. 1, 2 ... Mold 3 ... Lower mold centripetal device 4 ... Upper mold centripetal device 5, 7 ... Chuck 9, 10 ... Cup 13 ... Screw part 14 ... Pulse motor 15 ... Data processing device 16 ... … Data input device 17 …… Position measuring device 18 …… Data output device 19 …… Optical axis

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Claims (2)

[Claims] 1. A method of positioning a pair of molds for molding a plastic lens between a pair of molds facing each other, wherein the pair of molds is first constrained from the peripheral edge side. The center position of the mold using surface of the first mold of the pair of molds, and the position of the center of the mold using surface of the first mold of the pair of molds. Is measured, the position of the second mold in the optical axis direction to be set with respect to the measured position is calculated, and the second mold is held so that the second mold comes to the calculated position. A method for positioning a plastic lens molding mold, characterized in that the tool is controlled to move in the optical axis direction. 2. The measurement of the position of the central portion of the mold use surface of the first mold and the calculation of the position of the second mold in the optical axis direction to be set are performed with respect to a predetermined reference surface. A method for positioning a plastic lens molding mold according to claim 1.