JP2970790B2 - Suction and transport method for optical element members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a high-precision optical element such as an aspherical lens by press molding before and after press molding. The present invention relates to a method of adsorbing and transporting an optical element member which is used when the optical element member is sucked and conveyed by a suction action.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a method of directly press-molding a heat-softened glass material in a molding die instead of a method of processing an optical element by grinding and polishing. Usually, in this type of molding, a glass material in a softened state is pressed by using a molding die member composed of an upper and lower die that slides on the trunk die in the trunk die, and corresponds to a molding surface of the die member. Formed optical function surface on the glass material, and then cooled to disassemble the mold member, and in some cases, one of the upper and lower molds, separated from the formed optical element, and then the optical element Is used.

[0003] Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 297229/1999 proposes a vacuum chuck-type press-molded product releasing apparatus provided with a mold cooling mechanism. This is because after the press is completed, when the upper mold is raised and the press-formed product is taken out of the mold, a vacuum chuck equipped with a mold cooling mechanism enters the upper part of the lower mold, cools the lower mold, and cools the bellows. Then, the suction plate attached to the holder of the vacuum chuck is brought into contact with the molded product, and the molded product is taken out by vacuum suction.

Japanese Patent Application Laid-Open (JP-A) No. 64-43232 discloses a similar method of transferring by vacuum suction, in which a lens molding material and a lens are formed by suction holding means which are elastically pressed and urged downward and supported vertically. A method for adsorbing and conveying a molded article is disclosed.

[0005]

However, since the molding of the optical element by the press molding is performed at a high temperature of several hundred degrees, the temperature of the optical element member to be conveyed by suction is inevitably increased, and the suction member and the suction member used for that purpose are increased. An elastic body such as rubber cannot be used for the cradle, and a heat-resistant material such as metal must be used. Therefore, in the conventional example,
Since the molded optical element and the optical element member such as the optical element material before molding are first brought into contact with the adsorption member at the time of adsorption, a pressing force acts at the time of contact, so that the optical element member and the adsorption member are slightly separated from each other. There has been a problem that the positioning member is rubbed against the attracting member due to a misalignment or vibration generated from the apparatus side, causing optically harmful scratches and leaving a defect on an optical element as a final product. Also, when the optical element member is placed on the molding surface of the lower mold or the receiving table, when the optical element member comes into contact with the receiving surface of the lower mold or the receiving table, a similar problem occurs. Was. Furthermore, when the molded optical element is taken out of the mold, even if the molded optical element is released from the mold, the shapes of the mold and the optical element are almost the same, and the contact surfaces of both of them are optical. Because it is very smooth so that it has a function, the mold and the optical element are easily brought into close contact again with a slight pressure, making it impossible to remove the mold by vacuum suction. There was a problem.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an optical element that is a molded final product without causing harmful defects.
Also, when removing the molded optical element from the mold, the optical element can be smoothly removed from the mold without causing re-adhesion between the mold and the optical element. It is an object of the present invention to provide a method of adsorbing and transporting an optical element member which can be manufactured at a high speed.

[0007]

Therefore, in the present invention,
For example, at the time of suction of the optical element member, by performing vacuum suction with a gap of 2 mm or less provided between the suction unit and the optical element, even if the suction unit is made of a hard material such as metal, By not causing harmful scratches and the like on the optical element member, when the optical element to which the surface shape of the mold has been transferred is further sucked from the mirror-polished mold, a gap of 1 mm or less In order to prevent re-adhesion by performing vacuum suction in the state where the optical element member is provided, and to place the optical element member on the lower mold Suction is released from the state where a gap of 2 mm or less is opened between the table and the sucked optical element member, and the suction is released with some free fall to stably remove defect-free optical elements. , So that it can be manufactured continuously.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 schematically shows an automatic press forming apparatus of the present invention, in which a forming section A for heating an optical element material in an inert gas atmosphere such as a nitrogen gas atmosphere to perform press forming; A supply unit B for supplying the optical element material to A, and further taking out the molded optical element from the molding unit A into the atmosphere; And a robot unit C which carries out the optical elements obtained from the supply unit B and sequentially stocks them.

The molding part A includes a molding chamber 1 having an airtight structure, a molding die 2 installed therein, and a molding die 2.
Press mechanism 6 for opening and closing and pressurizing the mold, and a mold 2
And a swivel hand mechanism 12 for inserting the optical element material into the optical element and taking out the molded optical element. The molding die 2 inserts the upper die 4 and the lower die 5 into the body die 3 having the opening 3b for inserting and removing the optical element member from above and below a through hole formed substantially at the center. And a bottom plate 3a for restricting the position of the lower die 5 is screwed to the bottom thereof.

The press mechanism 6 includes a press shaft 7 having a hook 8 for lifting the upper die 4 of the molding die 2, and a press shaft 7.
And a press cylinder shaft 10 fastened to the press shaft 7. Further, the press shaft 7 maintains airtightness in the molding chamber 1. As shown in the figure, the space between the molding chamber 1 and the molding chamber 1 is sealed by an O-ring 11, and the upper die 4 is raised to insert an optical element material and take out the molded optical element in accordance with the movement of the press cylinder 9. And pressurization to the upper mold 4 for press molding.

The turning hand mechanism 12 includes a turning shaft 13 that is vertically set through the bottom of the molding chamber 1,
A turning arm 15 mounted horizontally on the turning shaft 13;
The suction arm 14 is attached to the tip of the revolving arm 15 in a state of being hung down. Swivel axis 1
Reference numeral 3 is attached to the molding chamber 1 via an O-ring (not shown) for maintaining airtightness, similarly to the press shaft 7, and similarly, a rotary turning mechanism (not shown) and a vertical movement mechanism are provided. As a result, as shown in the drawing, the swivel and the up-and-down operation can be performed, and the suction pipe 16 connected to the suction suction hole (not shown) provided in the axis of the swivel shaft 13.
Is connected to the suction suction hole 14a of the suction hand 14, inserts the optical element material supplied by the supply unit B onto the lower mold 5 of the molding die 2, and further lowers the molded optical element. It can be taken out of the mold 5 and placed on the supply section B. Further, a gate valve 17 is provided at a connection portion of the molding chamber 1 with the supply unit B, so that airtightness in the molding chamber can be maintained when the connection and the separation with the supply unit B are performed.

In the supply section B, the gantry 22 is mounted on the slide base 21, and the cylinder shaft 23 a of the cylinder 23 is fastened to the gantry 22, and the gantry 22 is moved in accordance with the movement of the cylinder 23. It can be moved horizontally over the. Furthermore,
A cylinder 31 is fixed to the upper part of the gantry 22,
The replacement chamber 27 is provided movably up and down via a cylinder shaft 31 a of the cylinder 31.

A shifter 24 is disposed so as to pass through the center of the replacement chamber 27, and a pedestal 25 of an optical element material and a pedestal 26 of a molded optical element are mounted on the upper part thereof. . The cylinder 30 is fixed to the lower part of the gantry 22, and the cylinder shaft 30 a of the cylinder 30 is fastened to the bottom of the shifter 24.
O-rings 28.29 are provided at the rubbing portions between the upper open surface of the replacement chamber 27 and the shifter 24, respectively, so that the airtightness in the molding chamber can be maintained when connected to the gate valve 17. ing.

The robot section C is used to move the pallet 32 on which the optical element material and the molded optical element are stocked, the suction finger 33 to which the suction exhaust pipe 34 is connected, and the suction finger 33 up and down. , And an XY stage 37 for horizontally moving the suction finger 33 to an arbitrary point on the pallet 32.

FIGS. 2 and 3 show a ball-shaped blank 40, which is an optical element material, which has been smoothed by polishing, flame treatment or acid treatment in the above-mentioned system. The state of the gap when the optical element 41 is sucked in each step or when the suction is released is shown.

FIG. 2A shows the suction finger 3.
3 shows a state of a gap La between the blank 40 and a contact portion (here, a conical suction surface) of the suction finger 33 when the blank 40 is sucked from the pallet 32, and FIG. When the blank 40 adsorbed from the pallet 32 is placed on the pedestal 25 of the optical element material,
The contact portion between the blank 40 and the cradle 25 (here,
(A conical surface).

Similarly, FIG. 2C shows a state in which the blank 40 is sucked from the receiving table 25 by the suction hand 14, and FIG. 2D shows a state in which the blank 40 is separated from the suction hand 14. FIG. 3A shows a state when the optical element 41 is placed on the lower mold 5, and FIG. 3B shows a state when the molded optical element 41 is sucked and removed from the lower mold 5 by the suction hand 14. The optical element 41 is separated from the suction hand 14, and the optical element
3 (c) is a state in which the optical element 41 is sucked from the receiving base 26 by the suction finger 33, and FIG. 3 (d) is a state in which the optical element 41 is sucked from the suction finger 33.
1 shows a state in which the blank 40 is placed on the pallet 32 by releasing the blank 40 from the blank 40 at the time of suction and release of suction, respectively.
And the optical element 41 and the suction hand 14 and the suction finger 33
With the inner periphery of the suction port (equivalent to the suction surface) and the cradle,
The required gaps Lc, Ld, Le, Lf, Lg, and Lh are shown. Also, in each gap,
The gaps La, Lb, Lg,
Lh can be adjusted by regulating the strokes of the cylinders 35 and 36. The gaps Lc, Ld, Le and Lf related to the suction hand 14 are, as shown, stoppers 14b provided on the suction hand 14. To the cradle 25, 2
It is secured by abutting on 6 and a part of the trunk mold 3.

Further, the suction hand 14, the suction finger 3
3, and a heater 26 (not shown) for controlling the temperature is built in the receiving table 26 so that the optical element immediately after molding at a high temperature does not crack due to a rapid temperature change.
The temperature is controlled, the suction hand 14 is made of molybdenum, the suction finger 33 and the pedestal 26 used in the atmosphere are made of stainless steel, and furthermore, a relatively high temperature (200
Similarly, the pallet 32 on which the optical element of about 350 ° C. is mounted and the pedestal 25 exposed to the high-temperature atmosphere are each made of stainless steel. Also, cradle 2
The holes 5, 26 and 32a are provided on the pallet 32 and the pallet 32 for the purpose of stabilizing the suction by easily applying a positive pressure to the anti-adsorption surface of the optical element member during the suction.

Next, the step of molding an optical element molded article using the above-described system will be described more specifically. The optical element molded here has a curvature of a surface formed by an upper mold used for a camera, a video camera, or the like.
= 16 mm, an aspheric lens with a diameter of 14 mm having a shape of approximately R = 15 mm with an approximate curvature of the aspheric surface of the lower mold, and the glass material used here has a temperature of 620.
It is SK12 having a viscosity characteristic of 10 ^9.5 poise at ℃, 10 ¹³ poise at 534 ° C. and 10 ¹⁶ poise at 480 ° C. The molding was performed in a closed furnace in an N ₂ atmosphere to prevent oxidation of the mold.

Before the start of molding, the amount of deviation between the suction center of the suction hand 14 and the suction finger 33 required for suction and release of suction and the center of the placement position of the lower mold 5, the receiving tables 25 and 26, and the pallet 32 is ±. After the centering is performed so as to be within 0.1 mm, as shown in FIGS. 2 and 3, Le = 0.3 mm among the respective gaps, and the remaining gaps are all 0.6 ± 0. It was adjusted to be 2 mm. Next, the suction hand 14 was set at 400 ° C., the cradle 26 was set at 275 ° C., and the suction finger 33 was set at 200 ° C., and the inside of the molding chamber 1 was replaced with a nitrogen atmosphere.

After the suction hand 14, the pedestal 26 and the suction finger 33 reached a predetermined temperature, molding was started. First, the cylinders 35 and 36 are raised, and the suction finger 33 is moved by the XY stage 37 to a position directly above the first blank 40 on the pallet 32.
5 and 36 are lowered to the state shown in FIG. 2A, and an adsorption source (not shown) connected to the suction pipe 34 for adsorption.
Was operated, and the blank 40 was sucked by the suction finger 33.

Next, the cylinders 35 and 36 are raised,
X so that the suction finger 33 is directly above the cradle 26.
After the Y stage 37 was moved, the cylinder 35 was lowered to the state shown in FIG. 2B, the suction was released, and the blank 40 was freely dropped on the receiving table 25. Next, with the blank 40 placed on the receiving table 25, the cylinder 23 is retracted, the supply unit B is moved below the gate valve 17, the cylinder 31 is operated, the replacement chamber 27 is raised, and the After the upper portion and the lower portion of the gate valve 17 are in close contact with each other via the O-ring 28, the portion surrounded by the replacement chamber 27 and the gate valve 17 is brought into a nitrogen atmosphere by a vacuum exhaust device and a nitrogen supply device (not shown). Replaced.

Thereafter, by opening the gate valve 17 and operating the cylinder 30, the shifter 24 is inserted into the inside of the forming chamber 1, and the swivel shaft 13 is swung down.
The stopper 14b of the suction hand 14 was applied to the shoulder portion of the receiving table 25 to bring it into the state shown in FIG. 2C, and the heating of the mold 3 was started at the same time. When the temperature of the mold reaches 450 ° C., the suction source is operated, the blank 40 is sucked by the suction hand 14, and the swivel shaft 13 is raised and swiveled, so that the suction hand 14 is turned into the body mold of the mold 2. 3 opening 3b
, The pivot shaft 13 is lowered again, and the stopper 14b of the suction hand is brought into contact with the body mold to bring the state shown in FIG. 2 (d), the suction is released, and the blank 40 is freely dropped on the lower mold. I let it.

After placing the blank 40 on the lower mold 5, the revolving shaft 13 is moved up and revolved, the suction hand 14 is returned to the position shown in FIG. 1, and when the mold 2 reaches 620.degree. The cylinder 9 was lowered, pressure was applied so that the blank 40 conformed to the shape of the cavity formed by the upper mold 4 and the lower mold 5, and cooling of the mold was started one minute after the pressurization.

On the other hand, the shifter 24 returns the cylinder 30 immediately after the suction hand 14 sucks the blank 40 from the cradle 25, closes the gate valve 17, returns the cylinder 31, and further ejects the cylinder 23. , Returned to the initial position shown by the dashed line in FIG.
As described above, the XY stage 37, the cylinders 35, 3
6 and the suction finger 33, the next blank is placed on the pedestal 25, and is inserted into the molding chamber 1 again through the same process as described above, and the previous blank is molded into the optical element and the molding die 2 is formed. And waited until it was removed from

When the temperature of the molding die 2 is cooled down to 450 ° C., the press cylinder 9 is raised, and the upper die 4 is pulled up by the hook 8 of the press cylinder shaft 10. 14 was inserted into the opening 3b of the body mold 3, and the pivot 13 was further lowered to bring it to the state shown in FIG. At this time, the gap La between the optical element 41 and the suction hand formed is 0.3 mm, which is a dimension that does not directly contact the optical element 41 and the suction hand 14 and that reliably sucks, as described above. Is set to

In the state shown in FIG. 3A, the optical element 41 is sucked by the suction hand 14, and the turning shaft 13 is raised and turned.
The suction hand 14 was carried on the receiving table 26, the rotating shaft 13 was lowered, the state shown in FIG. 3B was released, the suction was released, and the optical element 41 was freely dropped on the receiving table 26.
At this point, the heating of the mold 2 is started, and when the temperature of the mold reaches 450 ° C., the blank 40 already in the standby state is placed on the receiving stand 25 by the same process as described above. 2 was placed on the lower mold 5.

When the blank 40 on the receiving table 25 is sucked by the suction hand 14, the shifter 24 is returned to the initial position shown by the broken line in FIG. By the horizontal movement of 37 and the lowering of the cylinder 35, it comes to the position shown in FIG. 3 (c). The gap Lg (= 0.6 ± 0.2 m) shown in FIG.
In the state where m) is maintained, the optical element 41 is sucked by the suction finger 33, and moves up the cylinder 35, moves the XY stage, and moves down the cylinder 35.
In the state shown in (d), the blank was taken out by the suction release and placed on a predetermined position of the empty pallet 32 by free fall.

Thereafter, a new next blank is placed on the pedestal 25 in the same manner as described above, and
In order to carry out the optical element in the middle of molding by being inserted into the mold and to supply a blank to be molded next to the mold 2, the citafu 24 is inserted into the molding chamber, and the above-described steps are repeated. The element materials were sequentially formed, and optical elements having a desired shape were continuously produced.

Thus, using the above system,
Attempted molding of thousands of shots, but at the time of suction and suction release, the optical element molded under the condition of providing the above gap,
There is no occurrence of optically harmful scratches or the like due to the suction conveyance by the suction hand 14 or the suction finger 33,
Also, when taking out from the molding die 2, the suction hand 14
Thus, the molded optical element was not pressed, and the phenomenon of unremovability due to re-adhesion did not occur at all.

On the other hand, as in the prior art, the condition that the gaps between the respective parts are set to 0, the suction hand 14 and the swing arm 15
And between the suction finger 33 and the cylinder 35
A spring-like cushioning material is provided to reduce the shock at the time of contact between the optical element and the optical element. In the case of the optical element sucked and conveyed, defects such as harmful scratches due to contact were confirmed in almost half or more of the molded number. Further, when the optical element is removed from the lower mold 5 of the molding die 2, re-adhesion due to pressing occurs at a rate of 2 to 30%, and every time the operation of the apparatus is stopped, the mold release treatment is performed manually. Things were necessary, and continuous production was impossible at all.

Further, by changing the set value of each of the above gaps,
Using an optical element member of the same system and shape as above, as a result of conducting an experiment to determine the limit value of the gap of each part,
If the gap Le exceeds 0.6 mm, the adsorption becomes unstable,
When something that cannot be absorbed begins to occur, and exceeds 1 mm,
Most of the gaps other than the gap Le became incapable of being adsorbed. When the gap exceeded 1.2 mm, the adsorption was unstable as in the case of the gap Le, and when the gap exceeded 2 mm, the adsorption was similarly disabled. However, the occurrence of scratches or the like due to free fall at the time of suction release does not occur even if it exceeds 3 mm, and at the stage where it exceeds 5 mm, about 20% of the optical elements, in terms of optical functions, marginal scratches, Injuries were observed.

Separately from the above embodiment, a spherical lens having a diameter of 11 mm having a shape in which the curvature of the surface formed by the upper mold is R = 17 mm and the curvature of the surface formed by the lower mold is R = 8 mm. The state of the gap was verified, and substantially the same result as above was obtained. The stable range of the gap Le was 0.6 m.
m, the stable area of the remaining gap is 1.2 mm, and the gap Le
Is 1 mm, and the remaining gap exceeds 2.1 mm, the suction becomes impossible, and the occurrence of optically harmful scratches was confirmed at the point of time exceeding 6 mm.

In this embodiment, stainless steel or molybdenum is used as the material of the contact member of the optical element member.
Without being limited to this, it is clear that similar results can be obtained even if a heat-resistant ceramic, cermet, or the same hard metal as the mold material is used.

[0035]

As described above, according to the present invention, when the optical element member is conveyed by vacuum suction, at the time of suction, the optical element member is sucked and sucked with a predetermined gap.
Further, at the time of suction release, by performing suction release with free fall from a state having a predetermined gap, without causing optically harmful defects in the molded optical element,
In taking out the molded optical element from the molding die, it is possible to smoothly and stably produce a defect-free optical element continuously without causing a situation in which the optical element cannot be suctioned and taken out due to re-adhesion.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an automatic press forming apparatus used in one embodiment of the present invention.

FIG. 2 is a diagram illustrating a state of suction and conveyance of an optical element material used in the present invention.

FIG. 3 is a diagram illustrating a state of suction conveyance of an optical element used in the present invention.

[Explanation of symbols]

 A Molding part B Supply part C Robot part 1 Molding chamber 2 Mold 4 Upper die 5 Lower die 6 Press mechanism 12 Revolving hand mechanism 13 Revolving shaft 14 Suction hand 17 Gate valve 25 Receiving stand 26 Receiving stand 32 Pallet 33 Suction finger

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C03B 11/00 C03B 35/00

Claims (8)

(57) [Claims] In the step of sucking and transporting an optical element member, a predetermined distance is provided between the suction surface of the suction member and the optical element member when the optical element member is sucked by the suction member. And adsorbing the optical element member to the adsorption member. 2. The method according to claim 1, wherein in the step of adsorbing, conveying and placing the optical element member, when placing the optical element member adsorbed by the adsorption member on a lower mold forming surface of a molding die or on a receiving table,
With a predetermined gap between the lower mold forming surface or the receiving surface of the cradle and the optical element member, the suction to the optical element member is released, and the optical element is dropped at the interval. And mounting the optical element member on the lower mold forming surface or the receiving surface of the receiving table. 3. An optical element having an optical function surface formed by a molding die and at least a surface to be an optical function surface after molding is smoothly treated by polishing, acid treatment, flame treatment or the like. 3. The method according to claim 1, wherein the material is a material of the optical element. 4. The optical element member according to claim 1, wherein the suction surface of the suction member is made of a heat-resistant hard material such as a hard metal, metal, ceramic, or cermet. Suction conveyance method. 5. The lower mold and the receiving surface of the pedestal are made of a heat-resistant hard material such as a cemented carbide, metal, ceramic, or cermet. Of the optical element member by suction. 6. The distance is 2 mm or less, preferably,
3. The method according to claim 1, wherein the distance is in the range of 0.1 to 1.2 mm. 7. The method according to claim 1, wherein the step of sucking and transporting the optical element is a step of removing the optical element from the mold by suction. 8. The apparatus according to claim 1, wherein the distance is 1 mm or less.
8. The method according to claim 7, wherein the distance is in the range of 1 to 0.6 mm.
3. The method for adsorbing and transporting an optical element member according to item 1.