JP5399673B2 - Molding apparatus and method for manufacturing molded product - Google Patents

Description

  The present invention relates to a molding apparatus for optical glass elements such as glass lenses and prisms, and a method for producing a molded product. Specifically, a molding material (preform) such as a glass material is disposed between molds, and the mold and The present invention relates to a molding apparatus for molding a molded product such as an optical glass element by heating the molded material and pressing the molded material, and a method for manufacturing the molded product.

  In a molding apparatus that heat-softens preforms and press-molds, and includes upper and lower molds that can be contacted and separated from each other, with the upper and lower molds spaced apart from each other, the preform is placed on the lower mold, A molding processing apparatus is known that lowers an upper mold and performs a series of operations of heating, press molding, and cooling a preform (see, for example, Patent Document 1).

In such a glass forming apparatus, the mold is usually opened immediately after the pressing process is completed, and the cooling force is started by releasing the pressing force of the mold.
JP-A-5-186230

  However, the above technique has the following problems. That is, the above technique has a problem that the thickness accuracy of the molded product is low.

  Therefore, an object of the present invention is to provide a molding apparatus and a method for manufacturing a molded product that can improve the thickness accuracy of the molded product.

A method of manufacturing a molded product according to an example of the present invention includes disposing a molding material between a plurality of molds that are opened and closed, heating the molding material, and sandwiching the molding material with the mold closed. A pressing process for forming by pressing, and after the pressing process, the moving axis of the mold is stopped to control the relative positional relationship of the mold, thereby maintaining the relative positional relationship of the mold for a predetermined time. And a cooling step of cooling the workpiece after the maintenance step with the mold open, and the pressing force at the end of the maintenance step is the maximum pressing force in the pressing step. It is within the range of 1/20 to 1/5 .

According to another embodiment of the present invention, there is provided a method for manufacturing a molded article, wherein a molding material is disposed between a plurality of molds that are opened and closed, the molding material is heated, and the mold is closed to place the molding material. A pressing process for forming by sandwiching and pressing, and after the pressing process, the moving axis of the mold is stopped to control the relative positional relationship of the mold, thereby maintaining the relative positional relationship of the mold , A maintaining step for allowing the pressing force to reach a pressing force within a range of 1/20 to 1/5 of the maximum pressing force, and a cooling step for cooling the material to be molded by opening the mold after the maintaining step. And.

A molding apparatus according to another example of the present invention opens and closes by moving at least one of a pair of molds that open and close by being brought into contact with each other, a heating unit that heats the mold and the molding material, and the mold. Thus, a moving mechanism that press-molds the molding material and a cooling unit that cools the molding material after press molding, the moving mechanism after the press-molding process of the molding material is completed. Until the pressing force within the range of 1/20 to 1/5 of the maximum pressing force in the pressing step is reached, by controlling the relative positional relationship of the die by stopping the moving shaft of the die, The relative positional relationship of the mold is maintained.

A molding apparatus according to another example of the present invention opens and closes by moving at least one of a pair of molds that open and close by being brought into contact with each other, a heating unit that heats the mold and the molding material, and the mold. Thus, a moving mechanism for press-molding the material to be molded and a cooling unit for cooling the material to be molded after press-molding are provided, and the moving mechanism is predetermined after the press-molding process is finished. By controlling the relative positional relationship of the mold by stopping the moving axis of the mold until time passes and reaches within the range of 1/20 to 1/5 of the maximum pressing force of the pressing process. The relative positional relationship of the mold is maintained.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the shaping | molding apparatus which can improve the thickness precision of a molded article, and the manufacturing method of a molded article.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In each drawing, the configuration is appropriately enlarged, reduced, or omitted. FIG. 1 is an overall configuration diagram showing a molding apparatus according to a first embodiment of the present invention.

  The molding apparatus includes a frame 2 that constitutes an outline of the molding apparatus, a fixed shaft 1 (upper shaft) as a first shaft, a heat insulating member 3, a fixed die plate 4, a fixed die 5, an upper cavity die 6, and a second shaft. As a moving shaft 7 (lower shaft), a heat insulating member 8, a moving die plate 9, a moving die 10, a lower cavity die 11, and a control unit 18 for controlling these operations. The upper die 20 (die) is an assembly of the fixed die plate 4, the fixed die 5, and the upper cavity die 6. The lower die 21 (die) is the moving die plate 9, the moving die 10, and the lower cavity. It consists of an assembly of dies 11.

  The fixed shaft 1 as the first shaft has its upper end fixed to the ceiling of the frame 2. A fixed die plate 4 is attached to the lower end of the fixed shaft 1 via a heat insulating member 3.

  The heat insulating member 3 includes a hollow shaft member 3a made of a heat insulating material such as ceramics such as Si3N4 and a ring member 3b made of a transparent heat insulating material that transmits infrared rays such as transparent quartz glass.

  A fixed die plate 4 is connected to the heat insulating member 3 by a bolt or the like (not shown). An upper cavity die 6 made of ceramics or the like is attached to the fixed die plate 4 together with the fixed die 5.

  The moving shaft 7 as the second shaft is arranged coaxially with the fixed shaft 1. As described above, a hollow shaft member 8a is attached to the upper end of the moving shaft 7, and a moving die plate 9 is attached via a heat insulating member 8 composed of a ring member 8b.

  A lower cavity die 11 made of ceramics or the like is attached to the moving die plate 9 together with the moving die 10.

  In an open state in which the upper cavity die 6 and the lower cavity die 11 are separated from each other, a preform 15 that is a lens material (glass material) is placed on the lower cavity die 11 as a material to be molded. When the upper cavity die 6 and the lower cavity die 11 are heated and reach a predetermined temperature, the system connected to the moving shaft 7 (moving portion) is raised by the servo motor 16 as a driving device, and the fixed die 5 and the moving die 10 are moved. It will be in the closed state where the mating surfaces of the two are in close contact. The operation of the servo motor 16 that is a driving device is controlled by the control unit 18.

  As a result, the preform 15 is pressurized by the cavity 17 formed by the upper cavity die 6 and the lower cavity die 11 and pressed so that the preform 15 is deformed into a predetermined shape. Then, a convex lens) 15 'is formed.

  Further, an upper mold 20 composed of an assembly of the fixed die plate 4, the fixed die 5, and the upper cavity die 6, and a lower mold 21 composed of an assembly such as the moving die plate 9, the moving die 10, and the lower cavity die 11. Is in a molding chamber 25 under an inert gas atmosphere surrounded by a cylindrical chamber 24 whose openings at both ends are closed by a base 22 and a bracket 23.

  For example, when two lenses having an outer diameter of 15 mm are molded as the optical glass element 15 ′ (molded product), the outer shape of the upper die 20 and the lower die 21 is set to 65 mm for the fixed die 5 and the movable die 10. A quartz tube made of transparent quartz glass having an outer diameter of φ124 and a wall thickness of 3 mm was used as the chamber 24 that surrounds the chamber.

  Further, on the outer periphery of the chamber 24 made of quartz tube, a plurality of annular infrared lamps 30 as heating sources and aluminum provided in a state surrounding the back of the infrared lamps 30 are polished and gold-plated thereon. An infrared lamp unit 32 composed of a mirror 31 is arranged.

  Then, when the infrared lamp 30 (heating unit) is energized, infrared rays are transmitted through the chamber 24 to irradiate the upper mold 20 and the lower mold 21.

  The material of the fixed die 5 and the moving die 10 at this time is, for example, a tungsten alloy, the upper cavity die 6 and the lower cavity die 11 are made of SiC, and the glass material is an optical glass having a maximum yield temperature of about 600 ° C. .

  Infrared lamps 30 of 200 V, max 2 kW / 1 were used in 10 stages, heated while adjusting the output, and the thermocouple 35 was pressed at a display temperature of about 570 ° C. As a result of molding with a pressing pressure of 4 kN by the pressing force of the servomotor 16, a good optical glass element (lens) 15 'was obtained.

  In the embodiment, the infrared lamp 30 has the two infrared lamps 30 and 30 arranged in a substantially circular shape.

  A cooling unit 39 having a water cooling pipe 38 disposed on the back surface of the reflection mirror 31 is provided outside the infrared lamp unit 32 so as to prevent the reflection mirror 31 from being damaged by overheating. The cooling unit 39 is attached as necessary.

  The infrared lamp 30 is a halogen lamp using a coil coil of tungsten, and although its wavelength range is wide, it is generally an infrared lamp having a peak wavelength range of 1.2 μm to 1.8 μm.

  This wavelength passes through the chamber 24 made of a transparent quartz tube by 90% or more.

  Although there are some differences depending on the glass material, optical glass generally transmits most of infrared rays of 1.2 μm to 1.8 μm, so that the preform 15 is not substantially directly heated by the infrared lamp 30. Indirect heating.

  N2 gas, which is an inert gas, is introduced into the molding chamber 25 as indicated by arrows A, B, and C and exhausted as indicated by arrow D, so that the oxygen concentration in the molding chamber 25 does not affect the quality of the glass. Heating is performed after the concentration is lowered. A gas supply pipe and a gas exhaust pipe are omitted in the figure.

  The chamber 24 composed of the infrared lamp unit 32, the cooling unit 39, and the transparent quartz tube is integrally assembled with the bracket 23, and these can be integrally moved upward by an air cylinder as a driving device (not shown). The molding chamber 25 can be opened as necessary.

  The preform 15 can be easily loaded into the lower cavity die 11 of the lower mold 21 and the pressed optical glass element (lens) 15 'can be easily taken out.

  Hereinafter, the manufacturing method of the molded article in the glass forming apparatus according to the present embodiment will be described with reference to FIG.

  First, the molding chamber 25 is opened and the upper mold 20 and the lower mold 21 are separated from each other, and the preform 15 that is a lens material (glass material) is placed on the lower cavity die 11.

  Next, heat treatment is performed by the infrared lamp 30 after the oxygen concentration in the molding chamber 25 has decreased to a concentration that does not affect the quality of the glass.

  When the temperature reaches a predetermined temperature, the servo motor 16 as a driving device operates to raise the moving shaft 7 and the lower die 21 that moves with the moving shaft 7, and press molding processing is performed.

  When the lower mold 21 is raised and the preform 15 is in a closed state in contact with the upper mold 20, a pressing force starts to be applied to the preform 15. In the press forming process, the moving shaft 7 is moved to the set press end position and applied with the set press force. The maximum pressing force during this press forming process is defined as P2.

  Next, the moving shaft 7 is stopped at the press end position, and the relative positional relationship between the upper mold 20 and the lower mold 21 is maintained until a preset stop time t elapses (maintenance step). In addition, after the moving shaft 7 stops, the press force applied to glass falls.

  The set stop time t is a time required for the press force to sufficiently decrease. For example, the press force P1 at the end of the maintenance process (start of the cooling process) is in the range of 5% to 20% of the maximum press force P2. Set to the inner time. For example, the stop time t is about several seconds to 1 minute.

  After elapse of the stop time t, the moving shaft 7 is lowered to the open state, and the cooling process is started. In FIG. 2, the position at which the pressing force starts to be applied is different from the position at which the cooling process starts, but the opening / closing is performed by changing the dimensions of the preform 15 and the lens in the thickness direction (vertical direction). This is because the state switching position is shifted. That is, the position where the pressing force starts to be applied first, that is, the distance between the moving shaft and the fixed shaft at the time of switching from the open state to the closed state is larger, and the position where the closed state is opened is the moving shaft. The distance from the fixed shaft is small.

  In the cooling process, the temperature of the upper mold 20 and the lower mold 21 is slowly lowered with a predetermined gradient. The cooling step is performed, for example, by flowing an inert gas through the upper mold 20 and the lower mold 21. Further, water cooling is performed by the cooling unit 39. In addition, the cooling may be performed by reducing the output of the infrared lamp 30.

  As described above, the optical glass element 15 ′ as a molded product corresponding to the shape of the cavity 17 is press-molded with the movable die 10 in close contact with the fixed die 5.

  According to the glass forming apparatus and the glass forming method according to the present embodiment, the following effects can be obtained. In other words, after the pressing step, by providing a maintenance step for stopping the press shaft and maintaining the relative positional relationship between the upper die 20 and the lower die 21, deformation in the thickness direction of the molded product can be regulated. The accuracy in the thickness direction of the molded product is improved.

  For example, in the case where the thickness of the optical glass element 15 ′ is 3.5 mm, the thickness accuracy when entering the cooling process as an open state immediately after the pressing process described above as a comparative example was an error ± several tens of μm. According to the molding apparatus and the method for manufacturing a molded product of the above embodiment, the thickness accuracy of the molded product can be improved to an error of about ± several μm, for example, 2.3 μm.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the operation of the moving shaft 7 is controlled based on the elapsed time is illustrated, but the present invention is not limited to this. For example, the pressing force is detected at a collection interval of 0.1 sec, and this pressing force is detected. The movement of the moving axis may be controlled according to the above.

  That is, in the maintenance process, after the press molding process is finished, the moving shaft 7 is stopped at the press finish position until the relative positional relationship between the upper mold 20 and the lower mold 21 is maintained, and the press force is reduced to a predetermined press force. Let it pass. When the pressing force decreases to a predetermined pressing force, for example, P1, the moving shaft is lowered to an open state. At this time, the range of the pressing force P1 set as the predetermined value is preferably about 5 to 20% with respect to the maximum pressing force P2. If it becomes 5 to 20% from the experimental result, it can be determined that the reaction force from the shaft frame or the like is relaxed and stable.

  In addition, as a heating means for heating the preform 15 and the like to a predetermined temperature, the fixed die plate 4, the fixed die 5, the moving die plate 9, and the moving die 10 are induction heated by high frequency induction heating (RF induction heating), and induction is performed. It is also possible to indirectly heat the upper cavity die 6, the lower cavity die 11 and the preform 15 by heat conduction or radiation from the heated member.

  The optical glass glass material used as the preform 15 has many types, and the physical properties such as the refractive index are selected according to the purpose of use. However, since the glass transition point, the sag point, etc. change, the output of the infrared lamp 30 The required number also changes. Therefore, adjustment may be made by output control or replacement of the infrared lamp unit 32.

  In the above-described embodiment, SiC is used for the cavity dies 6 and 11, but ceramics such as TiC, Si3N4, and TiN, or the surface of these ceramics may be further coated with other ceramics or noble metals, Of course, the die plates 4 and 9 may be made of ceramics unlike the case of the high frequency induction heating method (RF), and various arrangements are possible.

In addition, it goes without saying that the present invention can be variously modified without departing from the scope of the invention. It is also possible to combine the features of a plurality of embodiments.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
(1)
A pressing step in which a molding material is disposed between a plurality of molds to be opened and closed, the molding material is heated, and the molding is closed by pressing the molding material in a closed state;
After the pressing step, a maintaining step of allowing a predetermined time to pass while maintaining the relative positional relationship of the mold,
After the maintaining step, a cooling step of cooling the molding material with the mold in an open state,
A method for producing a molded product, comprising:
(2)
A pressing step in which a molding material is disposed between a plurality of molds to be opened and closed, the molding material is heated, and the molding is closed by pressing the molding material in a closed state;
After the pressing step, a maintaining step for allowing the predetermined pressing force to pass while maintaining the relative positional relationship of the mold,
After the maintaining step, a cooling step of cooling the molding material with the mold in an open state,
A method for producing a molded product, comprising:
(3)
(1) or (2), wherein the pressing force between the dies at the end of the maintaining step is set within a range of 1/20 to 1/5 of the maximum pressing force in the pressing step. The manufacturing method of the molded article of description.
(4)
A pair of molds that open and close by contacting and separating from each other;
A heating section for heating the mold and the molding material;
A moving mechanism for press-molding the material to be molded by opening and closing by moving at least one of the molds;
A cooling unit for cooling the material to be molded after press molding;
With
The said moving mechanism maintains the relative positional relationship of the said mold | type until it reaches | attains a predetermined press force after completion | finish of the said press molding process of the said to-be-molded material.
(5)
The molding apparatus according to (4), wherein the predetermined pressing force is set within a range of 1/20 to 1/5 of the maximum pressing force of the pressing process.
(6)
A pair of molds that open and close by contacting and separating from each other;
A heating section for heating the mold and the molding material;
A moving mechanism for press-molding the material to be molded by opening and closing by moving at least one of the molds;
A cooling unit for cooling the material to be molded after press molding;
With
The said moving mechanism maintains the relative positional relationship of the said mold from the start of a press molding process until the predetermined time passes after the completion of the said press molding process.
(7)
The pressing force between the dies when the predetermined time elapses after the press molding process is finished is set within a range of 1/20 to 1/5 of the maximum pressing force of the press process. (6) The molding apparatus according to (6).

Sectional drawing which shows the structure of the shaping | molding apparatus which concerns on 1st Embodiment of this invention. The graph explaining the manufacturing method of the molded article which concerns on 1st Embodiment of this invention. The graph explaining an example of the manufacturing method of a molded article.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st axis | shaft (fixed axis | shaft), 7 ... 2nd axis | shaft (moving axis), 3 ... Heat insulation member, 3a ... Hollow shaft member, 3b ... Ring member, 8 ... Heat insulation member, 8a ... Hollow shaft member, 8b ... Ring member, 15 ... Preform (lens material, material to be molded), 15 '... Optical glass element (lens, molded product), 20 ... Upper mold (mold), 21 ... Lower mold (mold), 24 ... Chamber, 25 ... Molding chamber, 30 ... Infrared lamp (heating unit).

Claims (4)

A pressing step in which a molding material is disposed between a plurality of molds to be opened and closed, the molding material is heated, and the molding is closed by pressing the molding material in a closed state;
After the pressing step, by maintaining the relative positional relationship of the mold by maintaining the relative positional relationship of the mold by stopping the movement axis of the mold and controlling the relative positional relationship of the mold,
After the maintaining step, a cooling step of cooling the molding material with the mold in an open state,
And the pressing force at the end of the maintaining step is within a range of 1/20 to 1/5 of the maximum pressing force in the pressing step . A pressing step in which a molding material is disposed between a plurality of molds to be opened and closed, the molding material is heated, and the molding is closed by pressing the molding material in a closed state;
After the pressing step, the movement axis of the mold is stopped and the relative positional relationship of the mold is controlled, so that the relative pressing relationship of the mold is maintained and the maximum pressing force is 1/20 to 1/5. A maintenance step to elapse until a pressing force within the range is reached,
After the maintaining step, a cooling step of cooling the molding material with the mold in an open state,
A method for producing a molded product, comprising: A pair of molds that open and close by contacting and separating from each other;
A heating unit that heats the mold and the molding material; and a moving mechanism that press-molds the molding material by opening and closing by moving at least one of the molds;
A cooling unit for cooling the material to be molded after press molding;
With
The moving mechanism moves the mold after the press molding process of the molding material is completed until a pressing force within a range of 1/20 to 1/5 of the maximum pressing force in the pressing step is reached. A molding apparatus that maintains the relative positional relationship of the mold by stopping the shaft and controlling the relative positional relationship of the mold. A pair of molds that open and close by contacting and separating from each other;
A heating unit that heats the mold and the molding material; and a moving mechanism that press-molds the molding material by opening and closing by moving at least one of the molds;
A cooling unit for cooling the material to be molded after press molding;
With
The moving mechanism is configured so that a predetermined time elapses after the press molding process is completed for the material to be molded , and it reaches the range of 1/20 to 1/5 of the maximum press force of the press process . A molding apparatus that maintains the relative positional relationship of the mold by stopping the moving shaft and controlling the relative positional relationship of the mold.

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