JPH075327B2 - Mold centering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a die centering method applied to, for example, a press molding apparatus for optical lenses and the like, and particularly during mold clamping. The present invention relates to a die centering method for improving the precision of a molded lens by reducing the lateral misalignment of the upper and lower molds and maintaining the parallelism.

(Prior Art) In recent years, as a molding method of an optical lens, attention has been paid to a processing means by a polishing press, which requires complicated steps, to a processing means by heating a pre-measured glass lump to plasticize it and performing a precision press. It is coming.

Conventionally, in this type of optical lens press molding apparatus, as illustrated in FIG. 6, both upper and lower fixing plates 1,
2 is fixed with a tie bar nut 4 via a diver 3, a slide plate 5 is movably provided in the vertical direction between the upper and lower fixed plates 1 and 2, and the slide plate 5 is provided with a drive device 6 such as a hydraulic cylinder. And pushes it upwards by means of which the upper and lower molds 7, 8 installed between the upper fixed plate 1 and the slide plate 5
There is a configuration in which a lens molding material such as a raw material glass (not shown) is precision press-molded by clamping the mold.

However, in the above-mentioned conventional apparatus, the mold is clamped while sliding the slide plate 5 on which the lower mold 8 is supported and fixed on the tie bar 3 during press molding, as shown in FIG. Since a small amount of clearance a is required between the bush 9 provided on the slide plate 5 and the tie bar 3, a horizontal direction is always required when pushing up the slide plate 5 and when matching the upper and lower molds 7 and 8. Deviation occurs.

In the case of an optical lens, such a shift amount is normally required with a final accuracy of about 10 μm as an allowable limit, but as described above, in order to smoothly slide the slide plate 5 in the vertical direction. Requires a clearance a of 10 to 20 μm, which cannot meet the required accuracy.

Therefore, conventionally, the upper and lower molds 7 and 8 have a
A positioning hole 71 and a positioning pin 81 as shown in the figure, or a positioning recess 82 and a positioning projection 72 as shown in FIG.
By adopting a positioning mechanism composed of, for example, when the lower die 8 is raised by the slide plate 5, even if there is some misalignment, positional accuracy can be obtained when the upper and lower dies 7 and 8 are aligned. Has become.

(Problems to be solved by the invention) However, even in this case, 8 to 10 μm are provided in the mutual engaging portions.
m clearance is required, generally mold processing,
Considering the misalignment error of about 3 to 5 μm due to the assembling technology, there is a problem that it is difficult to secure the required accuracy.

Therefore, the inventors of the present application proposed a press molding device for an optical lens using a high precision guide device with almost no clearance in the mold moving part. In this case, the upper mold and the lower mold are accurately initialized. There is a need.

The present invention has been made under the above circumstances, and an object of the present invention is to enhance the mold matching accuracy and the parallelism of a mold when installing the mold in a press molding apparatus to achieve high precision optical It is an object of the present invention to provide a method for centering a mold that allows a lens to be obtained.

[Structure of the Invention] (Means for Solving Problems) In order to solve the above problems, the present invention comprises an upper mold and a lower mold when attaching the upper mold and the lower mold to a press molding apparatus. A flat portion is provided on the outer peripheral side surface of the die, and the flat portions of the upper die and the lower die are made to coincide with each other in the same plane.

(Operation) That is, according to the present invention, with the above configuration,
Since the flat portions provided on the upper mold and the lower mold are arranged so as to coincide with each other in the same plane, it is possible to improve the lateral misalignment accuracy of the mold. In that case, it becomes possible to mold a high-precision optical lens.

(Example) Hereinafter, the present invention will be described in detail with reference to an example shown in FIGS. 1 to 5. In the illustrated embodiment according to the present invention, the mold of the press molding apparatus for the optical lens shown in FIGS. 1 and 2 will be described as an example, but the invention is not limited to this.

FIG. 1 schematically shows the overall structure of an optical lens pressing device to which the present invention is applied. A column 12 is erected on the base 1, and a housing 13 is fixed on the column 12. In addition, the internal space of the housing 13 serves as a molding chamber 14. Then, while the upper die 15 is fixed to the upper ceiling surface 14a of the molding chamber 14 via the upper fixing plate 16, the lower bottom surface thereof is formed.
On the side of 14b, a lower die 17 which is interlocked with a driving means 18 which will be described later and which is installed on the lower surface of the housing 13 is disposed so as to face the upper die 15 and to be vertically movable.

That is, the drive means 18 includes a high-rigidity bracket 19 fixed to the lower surface of the housing 13 and having a strength that does not deform at least with respect to the mold clamping force, and a hydraulic cylinder 20 assembled to the lower portion of the bracket 19. , Swivel joint attached to the tip of cylinder rod 21 of this hydraulic cylinder 20
22 and a plurality of high precision guide devices 24 for vertically guiding the slider 23 assembled in the bracket 19 via the swivel joint 22. The high precision guide device 24 is shown in FIG. As shown in FIG. 3, the linear motion guide bearing (product name) is attached to the bracket 19 and is attached to the guide shaft 25a and the slider 23 so as to engage the guide shaft 25a with low sliding resistance and with high rigidity and positional accuracy. ) 25b, the slider 23 can be vertically guided through the high precision guide device 24, and the slider 23 has an upper end 26a on the bottom surface side in the housing 13. The press shaft 26 facing is assembled, and the lower die 17 is assembled and fixed to the upper end portion 26a of the press shaft 26.

According to this press forming apparatus, the press shaft 26 to which the lower die 17 is attached is assembled to the slider 23 which is slidably guided by the high precision guide device 24 including the guide shaft 25a and the linear motion guide bearing 25b. As a result, the sliding resistance is small, the rigidity is high, and the lower die 17 can be guided by sliding with a high positional accuracy of 1 to 2 μm. Further, since the hydraulic cylinder 20 as a drive source for vertical movement is attached to the lower part of the bracket 19 of the drive means 18 firmly attached to the housing 13, it is not affected by the reaction force of the mold clamping, and
Since the slider 23 is connected to the tip of the cylinder rod 21 of the hydraulic cylinder 20 by the swivel joint 22, the lateral displacement of the cylinder rod 21 is reduced by the slider 23.
Does not affect. Furthermore, since the drive means 18 is adapted to be directly attached to the housing 13, the parallelism at the time of assembling the housing 13 on the base 11 and the tie bar type as in the prior art at the time of centering are different. It will be much easier to do by comparison.

In order to mold a high-accuracy optical lens or the like with such a press molding apparatus, it is necessary to increase the misalignment accuracy of the upper mold 15 and the lower mold 17 at the time of initial setting.

That is, according to the present invention, in assembling the die including the upper die 15 and the lower die 17 to the upper fixed plate 16 and the upper end portion 26a of the press shaft 26 of the above-described high-precision press device, the upper die 15 is previously assembled.
Simultaneously with the molding process of the lens molding part on the outer peripheral side surface of the lower mold 17, as shown in FIG. 3, two flat parts 15a, 15b and 17a, 17b serving as the centering reference surfaces are notched so as to have a V shape. Form.

Then, the upper die 15 and the lower die 17 having such plane portions 15a, 15b and 17a, 17b are placed on the V-shaped base 31 of the die mounting jig 30 placed on the appropriate fixing surface A. Placed on this base
The flat portions 15a, 15b and 17a, 17b of the upper die 15 and the lower die 17 are aligned with the V-shaped reference surfaces 31a, 31b formed on the inner surface of 31 in the mold clamping state and left still (see FIG. 4). ).

Next, as shown in FIG. 5, a V-shaped pressing member 32 hinged to one end of the base 31 is used to wrap around the upper die 15 and the lower die 17 in a non-contact state, and to freely After fastening the end 32a to the other end of the base 31 with a fastening bolt 33,
The two push bolts 34, which are held through the top portion 32b of the pressing member 32, are tightened while maintaining the mold clamping state of the upper mold 15 and the lower mold 17, and are projected by tightening the respective push bolts 34. By pressing the flat portions 15a, 15b and 17a, 17b of the upper die 15 and the lower die 17 onto the V-shaped reference surfaces 31a, 31b formed on the inner surface of the base 31 by the push rod 35 to fix them, Flat parts 15a, 15b of the upper mold 15 and the lower mold 17 and
17a and 17b are formed in the same plane.

In this state, the upper mold 15 and the lower mold 17 fixed to the mold mounting jig 30 are first set on the upper end portion 26a of the press shaft 26, which is the lower mold mounting surface of the press molding apparatus in the open state. Then, the lower die 17 is fixed on the upper end portion 26a of the press shaft 26 from below by a bolt (not shown). In this way, the lower mold 1
After fixing 7 on the upper end portion 26a of the press shaft 26, the press molding device is operated as it is to be in a mold clamping state, and the upper mold 15 is brought into close contact with the upper fixing plate 16 which is the upper mold mounting surface of the press molding device. The upper mold 15 is fixed to the upper fixing plate 16 by a bolt (not shown) from above, and after the upper mold 15 and the lower mold 17 are fixed, the tightening bolt
The mold mounting jig 30 is removed from the press molding apparatus by loosening 33. As a result, the lateral misalignment accuracy of the die can be greatly improved, and the final misalignment accuracy can be increased to 5 to 8 μm even if various errors during molding due to the movement of the press shaft 26 are included. At the same time, the optical lens press-molding apparatus enables highly accurate molding of the optical lens.

In addition, in the above-mentioned embodiment, the flat surface portions 15a, 15b and 17 serving as two centering reference surfaces are provided on the outer peripheral side surfaces of the upper mold 15 and the lower mold 17.
Although a and 17b are provided, the invention is not limited to this, and at least 1
If the number is three or more, a sufficient centering effect can be obtained.

In addition, it goes without saying that the present invention can be variously modified and implemented within the scope of the present invention.

[Effects of the Invention] As is apparent from the above description, according to the present invention, since the plane portions provided on the upper die and the lower die are aligned in the same plane, the lateral direction of the die The center misalignment accuracy of the optical lens can be greatly enhanced, and thus, in the optical lens press molding apparatus, a die centering method having an excellent effect that a high precision optical lens can be molded is provided. What can be provided.

[Brief description of drawings]

The drawings show an example in which an embodiment of a die centering method according to the present invention is applied to a press molding apparatus for an optical lens, and FIG. 1 shows an example of a high precision press molding apparatus to which the present invention is applied. Fig. 2 is a schematic cross-sectional view, Fig. 2 is a cross-sectional view of the high-precision press-molding device portion taken along line II-II in Fig. 1, and Fig. 3 is mold clamping of a mold mounting jig used for centering the mold. FIG. 4 is an explanatory view showing a previously opened state, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is an explanatory view showing a mold clamping and fixing state of a mold mounting jig, and FIG. FIG. 7 is a schematic explanatory view of a general optical lens press molding apparatus, and FIG. 7 is an enlarged sectional view of an essential part of a sliding portion between a tie bar and a slide plate.
FIG. 8 and FIG. 9 are enlarged cross-sectional views of essential parts showing a conventional mold alignment mechanism. 15 …… Upper mold, 15a, 15b …… Flat part, 17 …… Lower mold, 17a, 1
7b: Flat surface, 30: Mold mounting jig, 31: Base, 31
a, 31b …… Reference plane.

Front page continued (72) Inventor Hisakage Sugiyama 2068 Ooka, Numazu City, Shizuoka Prefecture Numazu Works, Toshiba Machine Co. Ltd.

Claims (3)

[Claims] 1. When attaching an upper die and a lower die to a press molding apparatus, a flat surface portion is provided on an outer peripheral side surface of a die including the upper die and the lower die, and the flat surface portions of the upper die and the lower die are in the same plane. The method for centering a die is characterized in that 2. The method according to claim 1, wherein the reference surfaces of the die mounting jigs are pressed against the flat portions of the upper die and the lower die so as to be aligned in the same plane. How to center the mold. 3. An outer peripheral side surface of a die including an upper die and a lower die,
The centering method for a mold according to claim 1, wherein at least two flat portions are provided.