KR100355535B1 - Compression molding apparatus for glass products for cathode ray tube and its control method - Google Patents

Abstract

The present invention relates to a compression molding apparatus for a glass article for cathode ray tube and a control method thereof. A control method of a compression molding apparatus for a glass product for cathode ray tubes according to the present invention includes the steps of: lowering a plunger to contact and pressurize a glass gobe accommodated in a bottom mold to reach a predetermined first pressure of the plunger; Maintaining the first pressure for a predetermined time; And lowering the pressing force of the plunger from the first pressure to a predetermined second pressure. As a result, the optical properties and physical properties of the molded glass product can be improved, and compression parameters such as pressing force of the plunger for compression molding can be easily set.

Description

Compression molding apparatus for glass products for cathode ray tube and its control method

The present invention relates to a compression molding apparatus for a glass product for a cathode ray tube and a control method thereof, and more particularly, a bottom mold accommodating a molten glass gob, a withdrawal position to be withdrawn from the bottom mold, The present invention relates to a compression molding apparatus for a glass product for a cathode ray tube having a plunger installed to be able to move up and down between pressing positions for press-molding the glass gob at a filling interval of the glass gob, and a control method thereof.

In general, a cathode ray tube has a panel on which an image is projected, a funnel-shaped funnel coupled to the rear of the panel, and a neck coupled to the funnel with an electron gun. It is. The panel and the funnel are integrally bonded to each other by a method such as pleat sealing.

The molding of glass products such as panels and funnels is accomplished by heating the glass raw material in a glass melting furnace to make it into a predetermined molten state and pressing the molten glass gob provided in the compression molding apparatus.

1 is a schematic circuit diagram of a compression molding apparatus for a glass product for a cathode ray tube, and FIG. 2 is a view showing a stroke change and a change in pressing force of the ram of FIG. 1. As shown in these figures, the compression molding apparatus for the glass article for cathode ray tube includes a bottom mold 3, which is disposed on a turntable 1 rotatably installed to accommodate a molten glass gob 6, and a bottom mold ( 3) a ring-shaped shell mold 5 coupled to the phase, and a plunger 7 which is arranged at predetermined filling intervals with respect to the bottom mold 3 and the shell mold 5 to press-mold the glass gob 6 Has

The plunger 7 is coupled to the lower end of the ram 21 for elevating and driving the plunger 7, and the upper end of the ram 21 is reciprocated in the cylinder 9 installed to stand up at a predetermined distance from the turntable 1. The piston 19 accommodated as possible is coupled. The piston rod 23 is coupled to the upper end of the piston 19, and the piston rod 23 is provided with a so-called linear motion converter (not shown) to output a voltage proportional to the displacement of the piston 19.

Communication holes 11 are formed in the upper and lower regions of the cylinder 9 to allow oil to enter and exit the cylinder 9, and each communication hole 11 has an oil conduit having one end connected to the compression pump 20. (13) are respectively bonded. The oil conduit 13 connected to the upper region of the cylinder 9 is provided with a relief valve 15 so as to adjust the amount of oil, and the compression pump 20 and the relief valve 15 respectively receive oil. The tank 22 is connected to mutually communicate.

On the other hand, the lower end of the ram 21 is coupled to the square plate fixing plate 24, the fixing plate 24 is formed through the plate surface a plurality of through holes are formed. In each through hole, a guide rod 26 extending from an upper end of the plunger 7 provided to be spaced apart from the fixed plate 24 is accommodated so as to be slidable.

In the region between the fixed plate 24 and the plunger 7, spring members 28 are respectively coupled to surround the guide rod 26, and each spring member 28 has a plunger 7 having a fixed plate 24. As shown in FIG. The elastic force is applied in the direction away from the. In the region between the spring member 28 and the plunger 7 is provided with a pressure sensor 17 for detecting the pressing force on the glass gob 6 of the plunger 7 and outputting a detection signal to the control unit 27.

The control unit 27 has a built-in control program and includes a pressure sensor 17, a relief valve 15, a pressure pump 20, and the like, respectively. The control unit 27 further includes an input unit 29 and a display unit 31 so as to change compression parameters and the like of the control program.

By this configuration, when the glass gob 6 melted from the glass melting furnace is dropped into the bottom mold 3, the turntable 1 is rotated by a predetermined angle so that the bottom mold 3 in which the glass gob 6 is accommodated is plunged. Index to the bottom of (7). Then, the control unit 27 controls the compression pump 20 so that the oil is supplied in the upper space of the cylinder 9 and the oil in the lower space is discharged.

Accordingly, the ram 21 in the retracted position Hr is lowered such that the plunger 7 is in contact with the glass gob 6, as shown in the stroke change curve in FIG. 2 (T1 to T2), When the plunger 7 contacts the glass gob 6, the control unit 27 controls the compression pump 20 so that the pressing force of the ram 21 reaches a predetermined peak pressure P1 (T2 to T3). At the time T3 at which the pressing force of the ram 21 reaches the peak pressure P1, the controller 27 controls the relief valve 15 so that the pressing force is gradually reduced, as shown in the pressure change curve of FIG. (T3 ~ T4). When the pressing force is reduced to the predetermined second pressure P2, the controller 27 controls the pressure pump 20 so that the ram 19 is positioned at the pressing position Hp for a predetermined time T4 to T5. Ensure that pressure P2 is maintained.

At this time, the glass product molded in the molten state at a relatively high temperature releases heat to the outside through contact with the bottom mold 3, the shell mold 5, the plunger 7, and the like, whereby it is properly cooled to maintain strength. . At a time T5 after a predetermined time has elapsed, the control unit 27 causes the oil to flow into the lower space of the cylinder 9 at a high speed and the oil in the upper space is discharged to thereby quickly move the plunger 7 from the molded glass product. Withdraw it.

By the way, in the conventional compression molding apparatus for glass products for cathode ray tubes, the stroke position condition and the pressure condition of the ram 21 for compression molding of the glass gob 6 are simultaneously satisfied, If the stroke position is set low, there is a problem that the physical and / or optical properties of the molded glass product may be inhibited by continuously pressing the glass gob 6 at a peak pressure Ph without a pressure drop process. And, when the stroke position of the ram 21 is set high, there is a problem that the glass gob 6 may not be sufficiently filled in the cavity between the plunger 7 and the bottom mold 3. In addition, there is a problem in that a lot of trial and error may be experienced when changing the production lot of glass products or in setting desirable working conditions such as compression parameters of new products.

Accordingly, an object of the present invention is to provide a compression molding apparatus for a glass product for cathode ray tube and a control method thereof, which can improve optical characteristics and physical properties of the molded glass product and which can easily set compression parameters.

1 is a schematic circuit diagram of a compression molding apparatus for a glass product for a cathode ray tube;

2 is a view showing the stroke change and the change in the pressing force of the ram of FIG.

Figure 3 is a view showing the stroke change and the change in the pressing force of the ram of the compression molding apparatus of the glass product for cathode ray tube according to the present invention.

* Explanation of symbols for the main parts of the drawings

3: bottom mold 7: plunger

9: cylinder 11: communication hole

15: relief valve 17: pressure sensor

19: piston 20: compression pump

27: control unit 29: input unit

31: display unit

The object of the present invention is to pressurize the glass gob with a bottom mold accommodating the molten glass gob, a withdrawal position withdrawn from the bottom mold, and a filling interval between the bottom mold and the glass gob. A control method of a compression molding apparatus for a glass product for cathode ray tube having a plunger installed to be able to move up and down between positions, the method comprising: lowering the plunger and contact-pressing a glass gobe accommodated in the bottom mold to press a predetermined pressing force of the plunger. Reaching pressure; Maintaining the first pressure for a predetermined time; And a step of lowering the pressing force of the plunger from the first pressure to a predetermined second pressure.

Here, the step of reaching the first pressure may include increasing the pressing force of the plunger to a predetermined peak pressure, and reducing the pressure from the peak pressure to the first pressure.

And, it may be effective to further include the step of maintaining the second pressure for a predetermined time.

On the other hand, according to another field of the present invention, the bottom mold for receiving the molten glass gob, the bottom mold and the plunger is arranged at a filling interval of the glass gob and press-molding the glass gob, the plunger the bottom A compression molding apparatus for a glass product for cathode ray tubes having a driving means for raising and lowering between a withdrawn position withdrawn from a mold and a pressurized position for press-molding the glass gob, the pressure sensing pressure of the plunger against the bottom mold. A detection sensor; The plunger contacts and presses the glass gob to reach a predetermined first pressure based on a detection signal of the pressure sensor, and then maintains the first pressure for a predetermined time, and selects a predetermined first from the first pressure. Provided is a compression molding apparatus for a glass product for cathode ray tube, comprising a control unit for controlling the driving means to reduce the pressure to 2 pressure.

Here, the control unit preferably controls the driving means to depressurize the plunger to the glass gob to reach a predetermined peak pressure and then to reduce the pressure to the first pressure.

The controller may be effective to control the driving means to maintain the second pressure for a predetermined time.

Since the compression molding apparatus of the glass article for cathode ray tube according to the present invention is almost the same as the conventional compression molding apparatus in the configuration, a description of the basic configuration will be omitted and will be described below with reference to FIGS. 1 and 3. It demonstrates in detail.

When the molten glass gob 6 is dropped from the glass melting furnace not shown on the bottom mold 3 disposed on the turntable 1, the turntable 1 is rotated by a predetermined angle so that the bottom mold 3 is plunged 7. Indexed underneath). At this time, the ram 21 is present in the retracted position Hr from which the plunger 7 is withdrawn from the bottom mold 3, and the control unit 27 drives the plunger 7 downward toward the glass gob 6. The compression pump 20 is to be controlled.

When the compression pump 20 is driven, the oil in the lower space is discharged along the oil conduit 13 at about the same time as the oil is supplied into the upper space of the cylinder 9. Accordingly, the ram 21 in the retracted position Hr starts to descend at a predetermined speed from the time t1 at which oil is supplied into the cylinder 9, as shown in the stroke change curve in FIG. In contact with the glass gob (6). At the same time the plunger 7 is in contact with the glass gob 6, the pressing force is raised to a predetermined peak pressure Ph over the period t2 to t3. At this time, the descending speed of the ram 21 gradually decreases to nearly zero at the time t3 at which the pressing force reaches the peak pressure Ph.

On the other hand, when the pressing force of the plunger 7 reaches the peak pressure Ph, the control unit 27 controls the compression pump 20 so that the pressing force of the plunger 7 is substantially close to the peak pressure Ph. The pressure P1 is maintained for a predetermined time t3 to t4. This allows the glass gob 6 to be sufficiently filled in the cavity formed between the bottom mold 3 and the plunger 7 at a relatively high speed.

The control unit 27 operates the relief valve 15 at the time t4 at which it is judged that the glass gob 6 is sufficiently filled to return a part of the oil supplied to the upper space to the oil tank 22 so that the plunger 7 The pressing force on the glass gob 6 is gradually reduced (t4 to t5).

Next, the control unit 27 causes the second pressure P2 called so-called dwell pressure to be maintained from the time t5 to the time t6 at which the pressing force of the plunger 7 is reduced to reach the predetermined second pressure P2. At this time, the glass article molded in the molten state at a relatively high temperature is in contact with the plunger 7, the shell mold 5 and the bottom mold 3 to radiate heat, thereby being appropriately cured. At a time t6 where it is judged that the molded glass product is properly cooled, the control unit 27 controls the oil pump 20 so that the oil is rapidly supplied into the lower space in the cylinder 9, whereby it is in the pressurized position Hp. The ram 19 is moved to the withdrawal position Hr so that the plunger 7 is quickly withdrawn from the molded glass article.

As described above, according to the present invention, the optical properties and physical properties of the molded glass product can be improved, and the compression parameters such as the pressing force of the plunger for compression molding can be set with relatively little trial and error. A compression molding apparatus for glass articles and a control method thereof are provided.

Claims (6)

A plunger is provided to move up and down between a bottom mold accommodating the molten glass gob, a withdrawal position withdrawn from the bottom mold, and a press position for press-molding the glass gob at a filling interval between the bottom mold and the glass gob. In the control method of the compression molding apparatus for a glass product for cathode ray tube having a, Lowering the plunger to contact and press the glass gob received in the bottom mold to reach the pressing force of the plunger to a first pressure; Maintaining the first pressure for a predetermined time; And a step of lowering the pressing force of the plunger from the first pressure to the second pressure. The method of claim 1, The step of reaching the first pressure includes the step of raising the pressing force of the plunger to the peak pressure, and reducing the pressure from the peak pressure to the first pressure. Control method of the device. The method according to claim 1 or 2, The control method of the compression molding apparatus of the glass article for cathode ray tube, characterized in that it further comprises the step of maintaining the second pressure for a certain time. A bottom mold accommodating a molten glass gob, a plunger arranged at a filling interval between the bottom mold and the glass gob to press-mold the glass gob, a retracted position at which the plunger is withdrawn from the bottom mold and the glass gob In the compression molding apparatus of the glass article for cathode ray tubes which has a drive means which can raise and lower between the press positions which press-forms, A pressure sensor for sensing a pressing force of the plunger against the bottom mold; The plunger contacts and presses the glass gob to reach the first pressure based on the detection signal of the pressure sensor, and then maintains the first pressure for a predetermined time and decompresses the pressure from the first pressure to the second pressure. Compression molding apparatus for a glass product for a cathode ray tube, characterized in that it comprises a control unit for controlling the drive means. The method of claim 4, wherein And the control unit presses the plunger against the glass gob to reach a peak pressure, and then controls the driving means to reduce the pressure to the first pressure. The method according to claim 4 or 5, And the control unit controls the driving means to maintain the second pressure for a predetermined time.