JP3143572B2 - Glass element molding apparatus and glass element molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass mold for molding a glass lens of a camera or the like or a lens of plastic spectacles (hereinafter referred to as an optical glass element).
TECHNICAL FIELD The present invention relates to a glass element molding apparatus and a glass element molding method for molding glass by pressing.

[0002]

2. Description of the Related Art A glass material is arranged between a pair of upper and lower molds,
In a molding apparatus for heating the mold and the glass material to press-mold the glass material, a servomotor is used as a drive source of the press shaft, and the torque is applied to a linear motion thrust of the press shaft via a transmission mechanism such as a worm jack. With the function of performing the press as, the position control function of controlling the position of the moving die attached to the press shaft using the position detector, and the load detector arranged between the press shaft and the moving die, A device having a torque feedback function of detecting the load (pressing force) of the servomotor, and controlling the current value applied to the servomotor in a closed loop by a difference between the pressing force and a preset pressing force. When press forming, the shaft moves at a constant speed until the set press force is reached, and when the target press force is reached, the torque is controlled to maintain the set press force. .

[0003]

The movement of the moving shaft mold during press molding is controlled by the NC. Z F I P E Becomes Here, G100 is a torque control command, Z is the mold position, F is the moving speed of the moving shaft mold, I is the pressing force,
P represents a timer, and E represents the presence or absence of torque feedback.
When this command is issued, the movement of the moving shaft die and the pressing force can be divided into the following three. 1) Until the mold contacts the glass material from the preheating position, the mold has a constant set speed F Move with. At this time, the pressing force is 0 kgf.

[0004] 2) From the contact between the mold and the glass material, until the set pressing force is reached, the mold is driven at a constant set speed F. Move with. At this time, the pressing force changes depending on the shape and temperature (viscosity) of the glass material. For example, when the glass material is a sphere, the pressing force is small at the start of pressing because the contact area between the mold and the glass material is small, but as the pressing proceeds, the pressing force increases as the contact area increases. When the glass material is very close to the shape of the molded product, for example, when forming an aspherical lens, a spherical lens having a spherical surface similar to the aspherical shape has a small change in the contact area, so the pressing force is unloaded. It increases almost stepwise from the state to the set pressing force.

[0005] 3) After reaching the set pressing force, the mold moves so that the pressing force applied to the glass material becomes constant.

[0006] The change speed of the pressing force applied to the glass in the above "2) from the time when the mold and the glass material come into contact until the set pressing force is reached" is mainly governed by the moving speed of the shaft.
In addition, the pressing force could not be controlled due to the shape, temperature (viscosity) and size of the glass material, and the shape and size of the molded product. For this reason, depending on the shape and size of the glass material and the shape of the molded product, the pressing force increases almost stepwise, and an excessive force is applied to the glass, which may cause cracks and cracks. Further, if an excessive force is suddenly applied to the mold, there is a possibility that the mold is damaged, and the mold life is affected.

The present invention has been made based on the above circumstances, and provides a glass element molding apparatus and a glass element molding method capable of molding with high precision without causing cracks or cracks in the glass element to be molded. With the goal.

[0008]

According to the present invention, a glass material is disposed between a pair of upper and lower molds, and the mold and the glass material are heated.
A glass element forming apparatus for press forming the glass material, using a servomotor as a drive source of the press shaft, and a means for performing pressing as a linear motion thrust of the press shaft via a transmission mechanism such as a worm jack. A position control means for controlling the position of the moving mold attached to the press shaft using a position detector, and a load detector disposed between the servomotor and the moving mold, and the pressing force, which is the actual load, And a torque feedback means for controlling a current value applied to the servomotor in a closed loop by a difference between the press force and a preset press force. When the pressing force is changed to the pressing force, the pressing force P in the changing process is set to a function P ′ = f (t) of the time T, and the pressing force is changed according to the function. And it has a function of click feedback control.

[0009] Further, as a means of the method, there is provided a glass element molding method of placing a glass material between a pair of upper and lower molds, heating the mold and the glass material, and press-molding the glass material. Using a servo motor for the drive source,
A step of pressing the torque as a linear motion thrust of the press shaft via a transmission mechanism such as a worm jack, and a position control step of controlling the position of a moving mold attached to the press shaft using a position detector, A load detector disposed between the servo motor and the moving mold detects a pressing force, which is an actual load, and applies a difference between the pressing force and a preset pressing force to the servo motor. And a torque feedback step of controlling the current value in a closed loop. When the press force is changed from one set press force to another set press force, the press force P in the changing process is changed by a function P ′ = f of time T. (T), in which the press force is changed in accordance with the function and torque feedback control is performed.

[0010]

According to the glass element forming apparatus and the glass forming method of the above means, when the pressing force is changed from one set pressing force to another set pressing force, the changing pressing force P is changed to a function P 'of time T by a function P'. = F (t) and the pressing force is changed according to the function, the function P ′ =
f (t) is a function in which the pressing force gradually increases or decreases over time. As a result, it has become possible to obtain an optical glass element free from cracks and cracks without applying excessive force to the glass material.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows an example of an optical glass element molding apparatus in which a fixed shaft 2 extends downward from an upper portion of a frame 1 and a ceramic heat insulating cylinder 3 is provided at a lower end thereof.
The upper die assembly 4 is attached via bolts and the like (not shown).

The upper die assembly 4 includes a metal die plate 5,
An upper die 6 made of ceramic, cemented carbide or the like, and a fixed die 7 for attaching the upper die 6 to the die plate 5 and forming a part of the die.

A servo motor 8a is provided below the frame 1.
A driving device 8 such as a screw jack for converting the rotational motion of the servo motor 8a into a linear motion thrust is provided, and a moving shaft 9 as a press shaft is attached to the driving device 8 via a load detector 8b. Have been.

The moving shaft 9 moves up and down so that speed, position and torque can be controlled by a program input to the control device 28, and extends upward facing the fixed shaft 2. At the upper end of the moving shaft 9, a heat insulating cylinder 10 similar to the heat insulating cylinder 3 is provided.
The lower die assembly 11 is attached via bolts and the like (not shown).

The lower die assembly 11 includes a die plate 12, a lower die 13, and a moving die 14. A bracket 15 that is moved up and down by a driving device (not shown) is movably fitted to the fixed shaft 2. A transparent quartz tube 16 surrounding the upper mold assembly 4 and the lower mold assembly 11 forming a pair is attached to the bracket 15.

The lower end of the transparent quartz tube 16 is in airtight contact with the intermediate plate 1a through which the moving shaft 9 passes, and the molding chamber 1 is closed around the upper mold assembly 4 and the lower mold assembly 11 from the atmosphere.
7 are formed.

The transparent quartz tube 1 is mounted on the bracket 15.
An outer cylinder 18 surrounding the tube 6 is attached, and a lamp unit 19 is attached to the outer cylinder 18. Lamp unit 1
Reference numeral 9 denotes an infrared lamp, a reflection mirror 21 disposed behind the infrared lamp 20, and a water cooling pipe 22 for cooling the reflection mirror 21 and the like. The upper die assembly 4 and the lower die assembly 11 are heated. Has become.

The fixed shaft 2, the moving shaft 9, and the bracket 15 are provided with an inert gas atmosphere in the molding chamber 17,
Gas supply paths 23, 24, and 25 for cooling the upper mold assembly 4 and the lower mold assembly 11 are provided, and an inert gas is supplied to the molding chamber 17 at a predetermined flow rate via a flow controller (not shown). ing. The inert gas supplied to the molding chamber 17 is exhausted from the exhaust port 26. Reference numeral 27 denotes a thermocouple for detecting the temperature of the lower die assembly 11.

Next, with respect to the molding method of the present invention using the above molding apparatus, an actual program example (program example 1) incorporated in the control device 28 is shown below. (Program Example 1) Row Program 100 G01 Z45F800 110 G100Z49F20I300E1A1 120 G200Z55F20I10 E1V1A2 130 G200Z55F20I500E1V2A3 140 G200Z55F20I100E1V3A4 150 G01 Z0Z from the origin [Z axis] mm]. F is the moving speed of the moving shaft 9 [mm / min], I
Is a final press force "Kgf", E1 is a closed loop code for performing feedback control so as to maintain the set press force P, V is a forced stepping code output from the outside according to a set time and a set temperature, and G01 is A position control code for moving the moving axis by position control at a speed F to a position Z,
G100 is a torque control code for moving the moving axis at a speed F to a position Z and performing torque control with a pressing force P;
Until the position Z is reached or the forced stepping code V is received.
This is a torque control code for moving a moving axis at a speed F and performing torque control with a pressing force P. A is a code for controlling the pressing force from the start of the command to reaching the set pressing force P with the separately set pressing force P '.

The separately set pressing force P 'is a function of time and is represented by P' = f (t). Next, a method of molding an optical element using the molding apparatus will be described with reference to a program example (program example 1) incorporated in the control device 28 and FIG. 2 showing a molding profile at that time. The bracket 15 is raised along the fixed shaft 2 and the
Is opened and the glass material 30 is loaded onto the lower mold 13.

Next, the bracket 15 is lowered, the molding chamber 17 is closed by the transparent quartz tube 16, and the gas supply paths 23, 2
An inert gas is supplied from 4 and 25 to make the inside of the molding chamber 17 an inert gas atmosphere, and the driving device 8 is operated to move the moving shaft 9 from the origin Z =
Movement speed F = 800 [mm / mi] to the position of 45 [mm]
n].

The amount of movement of the moving shaft 9 is counted by an encoder (not shown) incorporated in the servomotor 8a, and is determined by position control at a position Z = 45 [mm] where the glass material 30 and the upper die 6 have a small gap. Can be

Next, the upper mold assembly 4, the lower mold assembly 11, and the glass material 30 are heated by the lamp unit 19 through the transparent quartz tube 16. The upper mold assembly 4, the lower mold assembly 11, and the heating of the glass material 30 control the output of the thermocouple 27 for temperature detection and the output of the infrared lamp 20 based on the output of the thermocouple 27.
The temperature is controlled by 8 so that the temperature of the glass material 30 is equal to or higher than the transition point and equal to or lower than the softening point and is set to a preset temperature T1.

Since the temperature of the glass material 30 cannot be directly measured and is replaced by the temperature of the lower mold assembly 11, a certain time (Soak Time) is required until the temperature of the glass material 30 reaches the temperature T1. It is desirable to set it.

When the preset Soak Time elapses, the command of the 110th line of the program example 1 is executed, the driving device 8 is driven, and when the pressing force P = 0 [Kgf] by the command of A1, The moving axis is the moving speed F = 20
Move at [mm / min], 0 <P <300 [Kgf]
In the case of, the set press force reaches 300 [Kgf] or
A position Z = 49 [m] where the upper and lower molds are slightly before the final mold closed state.
m], the glass material 30 is controlled by a separately set pressing force P ′ = f ₁ (t), which is a function of time, so that no unreasonable change occurs in the glass material 30.

When P = 300 [Kgf], torque feedback control is performed with the set pressing force P = 300 [Kgf] until the upper and lower dies reach a position Z = 49 [mm] slightly before the final mold closing state. . The pressing force applied to the glass material 30 is P ′ = f ₁ (t) or P = 30 irrespective of the shape and size of the glass material 30 according to the command of A1.
Since it is controlled to 0 [Kgf], there is no sudden change in the pressing force, no excessive force is applied to the glass material 30, and a high-precision optical glass element free from internal strain and cracks can be obtained. .

According to the instruction on line 110, the position Z = 49 [m
m], the instruction on line 120 is immediately executed, but the set pressure on line 110 is 300 [Kgf].
Is changed as a function of time to prevent the glass material 30 from being unduly deformed by the command of A2, and a separately set press force P '= f ₂ ( t).

When the set pressure P reaches 10 [Kgf],
The torque is controlled so as to maintain the set pressure P = 10 [Kgf].
Since the position is prioritized and the program moves to the next program, the set position is set to a position (virtual close contact position) Z = 55 [mm] higher than the actual mold contact position, and the glass material is set. Pressing force P = 10 [Kgf], which is set in advance, is maintained by torque feedback so that 30 does not deform.

Next, the infrared lamp 20 is turned off and the cooling process is started. During this time, the torque feedback control is performed with a pressing force P = 10 [Kgf] so that the glass material 30 is not deformed. Is held at the position Z = 49 [mm]. Since the moving shaft 9 moves following the contraction amount generated in the cooling process, it apparently moves above the position Z = 49 [mm], but the moving amount is equal to the contraction amount. Therefore, the gap between the upper and lower sides does not change.

Next, the command of line 130 is executed by the forced stepping code V1 output when the temperature T2 is reached. This command is for performing a final press. Said 1
The change in pressure from the set pressure P = 10 [Kgf] on line 20 to the set pressure P = 500 [Kgf] on line 130 is a function of time so that the glass material 30 is not unduly deformed by the command of A3. Press force P ′ =
It is controlled by f ₃ (t).

When the set pressure P = 500 [Kgf] is reached, torque feedback control is performed so as to maintain the set pressure P = 500 [Kgf], and the transfer surface of the mold is pressed against the glass material again to improve the transferability. As a result, the accuracy of the optical element can be further improved.

This operation is performed until the temperature T3 of the glass material 30 is reached, and the process proceeds to the 140th line by the forced stepping code V2 output when the temperature T3 is reached.
The change of the pressure from the set pressure P of the row P = 500 [Kgf] to the set pressure P = 100 [Kgf] of the row 140 is performed by a separately set press so that an unreasonable force is not applied to the glass material 30 by the command of A4. It is controlled by the force P '= f ₄ (t).

When the set press force P reaches 100 [Kgf], torque feedback control is performed so as to maintain the set pressure P = 100 [Kgf]. Since glass does not deform at a temperature lower than the glass transition point (Tg), the temperature T
3 is desirably a temperature near the glass transition point (Tg). When the temperature reaches the set temperature T4, the process moves to line 150 by the forced stepping code V3, the moving axis moves to the origin at a moving speed F = 800 [mm / min], the mold is opened, and the molding is completed. .

As described above, the present invention relates to the glass material 3
After heating 0 to a temperature equal to or higher than the transition point and equal to or lower than the softening point, the shaft 9 (the mold 13) is moved by torque control to a position slightly before the upper and lower dies 6, 13 are in the final mold closed state. Let it reach. Immediately after reaching the set position, the set position and the pressing force are accurately controlled by performing torque feedback control with such a small force that the glass material 30 is not deformed. Further, when the temperature of the glass material 30 is near the transition point, the final pressing is performed. In the above process, the pressing force is changed several times. At this time, according to the present invention, since the movement of the shaft (die) is controlled by the servomotor, not only the control of the final pressing force but also the pressing force is controlled. The present invention is directed to a glass element molding apparatus and a glass element molding method capable of controlling the pressing force in the process of increasing or decreasing even when the value is increased or decreased.

Accordingly, a high-precision optical glass element free from excessive force applied to the glass material and free from internal strain, cracks and cracks can be obtained. In the above-described embodiment, the infrared lamp 20 is used as the heating source. However, another heating source such as high-frequency heating may be used.
b may be provided not only between the driving device 8 and the moving shaft 9 but also between the servomotor 8a and the lower mold 12. Further, it is a matter of course that various changes can be made in the cooling step of the glass material, for example, a slow cooling section may be provided.

[0036]

As described above, according to the glass element forming apparatus and the glass element forming method of the present invention, after the glass material is heated to a temperature between the transition point and the softening point,
The shaft (die) is moved by torque control to a position slightly before the upper and lower dies close to the final mold closed state, and reaches the set position. Immediately after arriving at the set position, the set position and the pressing force are accurately controlled by performing torque feedback control with a small force so that the glass material is not deformed. Further, when the temperature of the glass material is near the transition point, final pressing is performed. In the above process, the pressing force is changed several times. At this time, according to the present invention, since the movement of the shaft (die) is controlled by the servomotor, not only the control of the final pressing force but also the pressing force is controlled. When increasing or decreasing the pressure, the pressing force during the increasing or decreasing process can be controlled, and no excessive force is applied to the glass material, and a high-precision optical glass element free from internal strain, cracks and cracks. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an optical element molding apparatus according to the present invention.

FIG. 2 is an explanatory view of an example of a molding profile for realizing the present invention.

[Explanation of symbols]

2: fixed shaft, 4: upper die assembly, 5: die plate, 6: upper die, 7: fixed die, 8: driving device, 8a: servo motor, 8b: load detector, 9: moving shaft, 11: lower Mold assembly,
12: die plate, 13: lower die, 14: moving die, 1
5 bracket, 16 transparent quartz tube, 17 molding chamber, 1
9 lamp unit, 20 infrared lamp, 23, 2
4, 25: gas supply path, 27: thermocouple for temperature detection, 28
... control unit, 30 ... glass material.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihisa Kamano 2068-3 Ooka, Numazu-shi, Shizuoka Toshiba Machine Co., Ltd. Numazu Office (72) Inventor Isao Matsutsuki 3068 Ooka, Numazu-shi, Shizuoka Toshiba Machine Co., Ltd. Numazu Plant (58) Field surveyed (Int. Cl. ⁷ , DB name) C03B 11/16 C03B 11/00

Claims (3)

(57) [Claims] 1. A glass element forming apparatus for arranging a glass material between a pair of upper and lower dies, heating the dies and the glass material, and press-forming the glass material. Means for pressing the torque as a linear motion thrust of the press shaft via a transmission mechanism such as a worm jack, and position control for controlling the position of a movable mold attached to the press shaft using a position detector. Means, and a load detector arranged between the servomotor and the moving mold detects a pressing force which is an actual load, and calculates a servo by a difference between the pressing force and a preset pressing force. Torque feedback means for controlling the current value to be applied to the motor in a closed loop by a torque, when the press force is changed from one set press force to another set press force, Function P '= f the press force P of time T
(T), a function of changing the pressing force according to the function and performing torque feedback control. 2. The glass element forming apparatus according to claim 1, wherein said function P '= f (t) is a function in which the pressing force gradually increases or decreases as time passes. 3. A glass element forming method for disposing a glass material between a pair of upper and lower dies, heating the dies and the glass material, and press-forming the glass material. And presses the torque as a linear motion thrust of the press shaft via a transmission mechanism such as a worm jack, and position control using a position detector to control the position of the moving mold attached to the press shaft. Process, a load detector arranged between the servomotor and the moving mold detects a pressing force, which is an actual load, and calculates a servo by a difference between the pressing force and a preset pressing force. A torque feedback step of controlling the current value applied to the motor in a closed loop, and when changing the press force from one set press force to another set press force,
A method of forming a glass element, wherein a pressing force P in a changing process is set to a function P ′ = f (t) of time T, and the pressing force is changed according to the function to perform torque feedback control.