JP2004149410A - Glass lens forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass lens forming apparatus capable of manufacturing a low-cost high-precision formed glass lens by high-frequency induction heating without using a high-precision former. <P>SOLUTION: A forming tool A consisting of a barrel die 1, an upper die 2 and a lower die 3 is constructed so that the tool A is subjected to high-frequency induction heating, the lower die 3 is supported by a stationary part 4 and three protrusions 4a, 4b, 4c of a former B, and the upper die 2 is supported by a movable part 5 and one protrusion 5a of the former B. The barrel die 1, the upper die 2 and the lower die 3 are made of a ceramic material difficult to induction-heat, parts 2b, 3b for heating comprising a metallic material easy to induction-heat or elements for heating are disposed in the upper die 2 and the lower die 3, and by induction-heating these, a cavity is heated to form a glass lens. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a glass lens forming apparatus that is formed by induction heating in the field of forming glass lenses used in optical instruments.

2. Description of the Related Art Conventionally, in order to improve molding accuracy, a molding apparatus for glass lenses has been devised so as to maintain molding accuracy of a lens while fixing a molding die to a molding machine (for example, see Patent Document 1). There is a type in which a molding die is not fixed to a molding machine so that the molding die is hardly affected by the molding machine (for example, see Patent Document 2). In many cases, a glass lens is formed by a high-frequency induction heating method (also described in Patent Documents 1 and 2). For example, in Patent Document 3, a glass lens surface is formed. A configuration is adopted in which a member (a holding component or the like) surrounding the upper and lower molds is heated. Patent Document 4 also adopts a configuration in which a member surrounding a plurality of opposed upper and lower dies is further heated from the outer periphery and the heat is transferred to a lens molding portion. Further, Patent Document 1 discloses a configuration in which induction coils are provided on the outer peripheries of a plurality of opposed upper and lower dies.
JP-A-6-206732 (FIG. 2) JP-A-5-24868 (FIGS. 4 and 6) Patent No. 2509305 JP-A-5-163029

  However, in the above-mentioned fixed mold type, since the precision of the formed lens depends on the precision of the molding machine itself, a molding machine assembled with high precision is required, and as a result, there is a problem that the lens cost is increased.

  In addition, even in the above-mentioned non-fixed type, heat during molding is transferred to the molding machine side, and thermal distortion occurs in the molding machine, and it becomes difficult to maintain molding accuracy, and since the heating structure generally has a large loss, However, it has not been possible to solve the problems such as that it takes time to raise and lower the temperature, and the molding cycle becomes longer.

  As a problem due to the induction heating, in the configuration shown in Patent Document 3, the outer peripheral member surrounding the upper die and the lower die, which are opposed to each other for forming the glass lens, is mainly induction-heated. Therefore, the temperature of the outer peripheral member is higher than that of the upper and lower molds held inside. For this reason, it is difficult to maintain the positional relationship between the outer peripheral member and the inner upper and lower dies, which require high-precision coaxiality and the like, because the clearance is widened at high temperatures. Therefore, in such a configuration, there is a problem in manufacturing an optical lens that requires high eccentricity. In addition, in glass lens molding which needs to be set to a predetermined temperature, since heating is performed by heat conduction from the outer peripheral member without directly heating the upper and lower molds, it takes time to raise and lower the temperature, and the cycle time is longer. The problem also arises. Further, in the configuration shown in Patent Document 4, the following problem occurs in addition to the above problem. That is, in the heating by the induction coil, the current flows to the surface layer of the object to be heated, and the heating is performed from the surface. Therefore, in a mold configuration in which a plurality of upper molds and lower molds are arranged in one induction coil, as described above, a temperature gradient occurs in the radial direction of the mold. Therefore, the temperature of the upper and lower dies facing each other for forming the individual glass lenses is different between the inner circumference and the outer circumference of the induction coil, which makes it difficult to obtain a rotationally symmetric engineering lens. Similarly, it is difficult to make the characteristics of a plurality of lenses in a mold the same, and the yield in the manufacturing process becomes a problem. To solve this problem, a configuration disclosed in Patent Literature 1 has been proposed. However, since the configuration of the induction coil is complicated and restrictions on the die configuration are increased, practical application is difficult.

  The present invention solves the above-described problems, and by improving the relationship between the molding machine and the molding die and the induction heating method, the temperature rising speed is high, and a high-precision lens can be efficiently molded by a molding machine that does not require accuracy. It is an object to provide a glass lens forming apparatus.

  The glass lens molding apparatus according to the present invention has one of the cavities forming the optical surface of the glass lens, and has an upper mold at the upper end which receives a pressing force from a movable portion of the molding machine, and has the other of the cavity of the upper mold, A molding die for a glass lens comprising: a lower die supported by a fixing portion of a molding machine; and a barrel die which is close to a peripheral surface of the upper and lower dies and holds the upper and lower dies so as to be relatively movable vertically. Heating means for high-frequency induction heating of a heated portion formed in the upper and lower molds of the same mold, cooling means for cooling the mold, which is located close to the heating means, and A temperature detecting means for controlling the heating means and the cooling means, which is provided in proximity to the cavity of the mold, wherein the upper mold of the molding die is added to the movable means of the molding machine via one projection; The lower mold of the above mold is Characterized in that it is supported via the fixing means and the three protrusions form machine.

  Further, the glass lens forming apparatus according to the present invention has one of the cavities forming the optical surface of the glass lens, and has, at the upper end, an upper mold receiving a pressing force from a movable portion of the molding machine, and the other of the cavities of the upper mold. A molding die for a glass lens comprising a lower die supported by a fixing portion of the molding machine and a body die for holding the upper and lower dies so as to be relatively movable in the vertical direction in proximity to the peripheral surfaces of the upper and lower dies, The heating means includes a heating unit located in close proximity to the mold and for performing high-frequency induction heating of a heated portion of the mold, and a cooling unit located in proximity to the heating means and cooling the heating unit and the mold. The upper and lower molds are made of a material easily heated by induction heating, and the body mold is made of a material hardly heated by induction heating.

  Further, the glass lens forming apparatus according to the present invention is characterized in that the upper mold and the lower mold of the above-mentioned mold are partially made of a material which can be easily subjected to induction heating.

  Further, the glass lens forming apparatus according to the present invention is characterized in that a ceramic material is used for the upper mold and the lower mold, and a metal material which is easily induction-heated is sprayed on the surface.

  Further, the glass lens forming apparatus according to the present invention is characterized in that a groove is provided on the outer periphery of the upper mold and the lower mold, and a metal material which is easily induction-heated is arranged in the groove.

  Further, the glass lens forming apparatus according to the present invention is characterized in that the depth of the groove formed in the upper mold and the lower mold is larger than the thickness of the metal material provided in the groove.

  Further, in the glass lens forming apparatus according to the present invention, the heated portion of the mold to be induction-heated is provided at an upper portion of the upper mold and a lower portion of the lower mold, and a heating means is positioned opposite to the heated portions. It is characterized by the following.

  Further, in the glass lens forming apparatus of the present invention, the heating means is provided with an upper heating means for heating the upper mold and a lower heating means for heating the lower mold independently, so that the temperature can be controlled separately. It is characterized by the following.

  Further, the heating means of the glass lens forming apparatus according to the present invention is characterized in that it can move up and down to change the heating state.

  Further, the heating means of the glass lens forming apparatus according to the present invention winds a high-frequency induction coil around a cylindrical body and forms a spiral groove on an inner peripheral surface facing the outer periphery of the body mold, and forms a gas in this groove. To cool the mold.

  Further, the glass lens forming apparatus according to the present invention is characterized in that one or both of the upper mold and the lower mold is provided with a hole drilled to a position close to the cavity, and the temperature detecting means is arranged in this hole. I do.

  Further, the glass lens forming apparatus according to the present invention is characterized in that the axial length of the barrel of the forming die is at least three times the inner diameter of the barrel.

  Further, the glass lens forming apparatus according to the present invention is characterized in that the thermal conductivity of the body mold of the forming die is smaller than that of the upper and lower molds.

  Furthermore, the glass lens forming apparatus according to the present invention includes a heating target made of a material easily induced by induction heating inside one or both of an upper mold and a lower mold which are arranged to face each other to form a cavity of a glass lens. The heating target is subjected to high-frequency induction heating, and the glass lens in the cavity is heat-formed by heat conduction of the heating target.

  Further, the glass lens forming apparatus according to the present invention is characterized in that the upper mold and the lower mold are made of ceramic, and the object to be heated provided therein is made of a magnetic material containing any of iron, nickel and cobalt.

  Further, the glass lens forming apparatus according to the present invention is characterized in that the object to be heated is disposed so as to surround the cavity.

  Further, in the glass lens forming apparatus according to the present invention, the object to be heated is provided at a position far from the cavity, and is heated at a position near the cavity so as to be made of a material that is harder to induction heat than the object to be heated. It is characterized by having a body.

  Further, the glass lens forming apparatus according to the present invention is characterized in that a body to be heated is provided in each of the upper mold and the lower mold having a plurality of cavities in correspondence with the respective cavities.

  Further, the glass lens forming apparatus according to the present invention is characterized in that a heated body for heating the entire plurality of cavities is provided in addition to the heated body.

  According to the present invention, when the molding die of the glass lens is assembled to the molding machine, the fixing portion of the molding machine supports the molding die through three projections without fixing the molding die to the molding machine. Therefore, the position of the mold is uniquely determined, and problems such as wobble can be eliminated. On the other hand, since the movable part of the molding machine presses the molding die through one point of projection, it can be pressurized without being affected by the parallelism of the movable part of the molding machine. Molding can be performed based on the precision of the mold without depending on the precision of the mold. Also, since the lower mold is supported at three points and the upper mold is pressed at one point by the projections, the contact area between the mold and the molding machine is small, and the heat transfer to the molding machine during heating and cooling of the mold. Can be reduced as much as possible, thereby preventing an increase in the molding cycle time due to heat transfer and enabling high-speed glass lens molding at low cost. In addition, by configuring the upper die of the forming die so that it can be centered in the horizontal direction and the rotating direction, it is highly accurate and stable without depending on the machine accuracy such as the parallelism of the pressurized part of the forming machine, squareness, etc. Molding can be performed.

  According to the present invention, the heating of the mold is performed by high-frequency induction heating, and the induction coil is configured to directly heat the upper and lower molds from the outer peripheral portion or the upper and lower surfaces of the mold. Heating can be efficiently performed by reducing heating to a structure located around the object. In addition, since the upper and lower dies can be intensively heated by using a material in which the body die is not induction-heated, for example, made of ceramics, it is possible to reduce the time required to heat the cavity of the upper and lower dies. In addition, the body mold and the upper and lower molds are made of ceramics, and the high-frequency induction-friendly metal is arranged on the outer periphery of the upper and lower molds, so that the clearance between the body mold and the upper and lower molds, which is configured with a high degree of fitting, can be molded Heat transfer from the outer peripheral portion is eliminated, and stable operation can be maintained even at high temperatures. Specifically, if a groove is provided in the outer peripheral portion of the upper and lower molds and the metal is sprayed in the groove, a highly accurate heated portion can be easily formed.

  Further, by using two high-frequency induction coils, the temperatures of the upper mold and the lower mold are independently controlled, and fine heat control is enabled. Further, the heating state of the upper and lower molds can be changed by making the heating means vertically movable. In addition, these high-frequency induction devices use a hole provided in the center of one or both of the upper mold and the lower mold to arrange temperature detection means, and perform temperature measurement in real time, so that precise temperature control is possible. it can. Further, by setting the axial length of the barrel of the molding die to be at least three times the inner diameter of the barrel, the eccentricity of the lens can be improved. Furthermore, by making the thermal conductivity of the body mold smaller than that of the upper and lower molds, heat radiation from the body mold is reduced, so that the temperature variation in the cavity between the upper mold and the lower mold is reduced, High-precision glass molding becomes possible.

  Further, according to the present invention, by providing one or a plurality of objects to be heated made of a material which can be easily subjected to induction heating in one or both of the upper and lower molds, the time required for the temperature to reach a predetermined temperature by induction heating is increased. Can be shortened.

  Further, according to the present invention, by providing a heated body made of a material which is easily induction-heated so as to surround the cavity formed in the upper and lower molds, the time required for heating can be reduced and the temperature distribution in the glass forming surface can be uniform. Can be achieved.

  Further, according to the present invention, by combining a heated body made of a material that is easily induction-heated and a heat relaxation body made of a material that is more difficult to induction-heat in comparison with this, glass that avoids local heating can be avoided. The temperature distribution in the molding surface can be made uniform.

  Furthermore, according to the present invention, even when the upper and lower molds have a plurality of lens forming cavities, a plurality of objects to be heated, which are made of a material easily induced by induction heating, are arranged so as to surround the individual cavities. Similarly, it is possible to shorten the time required for raising the temperature and to make the temperature distribution in the glass forming surface uniform.

  As described above, according to the present invention, a high-precision glass lens can be molded at low cost only by the precision of a molding die, regardless of the precision of a glass molding machine, and efficiently by high-frequency induction heating according to the present invention. The upper and lower molds can be heated, so that a high-quality, high-precision glass lens can be formed.

(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a glass lens molding die and a molding device thereof. The glass lens molding die A includes a cylindrical trunk die 1, an upper die 2 which is inserted into the trunk die 1 from the upper side so as to be vertically movable, and the above-mentioned trunk. A lower mold 3 is inserted from the lower side of the mold 1 so as to be vertically movable. On the lower surface of the upper mold 2 and the upper surface of the lower mold 3, cavities 2a and 3a for transferring the optical surface of the glass lens to form the glass lens are formed. The length of the body mold 1 in the axial direction is set to be smaller than that of the upper and lower molds 2 and 3 in order to make the fitted state of the body mold 1 and the upper and lower molds 2 and 3 dense and improve the eccentricity of the molded lens. It is experimentally desirable that the diameter is three times or more.

  The lower mold 3 is supported at three points by protrusions 4a, 4b, and 4c provided on the fixing portion 4 of the molding machine B. The positions of the protrusions 4a, 4b, and 4c are selected so as to form a triangle having an apex on the circumference of a circle centered on the pressing center axis of the molding machine, and a position that becomes an equilateral triangle is preferable. As a result, the mold A is securely supported without shaking during molding, and the contact area of the protrusions 4a, 4b, 4c with the mold A is extremely small. Heat transfer can be reduced.

  The upper mold 2 is pressurized by the movable part 5 of the molding machine B at the time of molding. In the present embodiment, the upper mold 2 is supported at one point by the projection 5a provided on the movable part 5, and its position is It is preferable that the position be on the center axis of the pressure and be as close as possible. Thereby, the molding can be performed without worrying about the parallelism between the movable portion 5 and the upper surface of the upper mold 2, and an advantage that does not affect the accuracy of the molded glass lens is exhibited. At the same time, the heat transfer between the molding die A and the molding machine B can be minimized for the same reason as in the case of the projections 4a, 4b, 4c.

  In the present embodiment, the projections 4a, 4b, 4c and 5a are provided on the fixed part 4 and the movable part 5 of the molding machine. However, they may be provided on the lower mold 3 and the upper mold 2, For example, a steel ball may be interposed between the fixed part and the lower mold, and between the movable part and the upper mold.

  The body mold 1, the upper mold 2, and the lower mold 3 are made of ceramics, and are preferably made of aluminum nitride or silicon carbide having good thermal conductivity, but ceramics such as alumina do not cause any problem. As the material has a better thermal conductivity, rapid heating and rapid cooling are possible, and the cycle time during lens molding can be shortened. In addition, it is also possible to change the type of ceramic in the body type, the upper type, and the lower type. For example, by manufacturing the body mold from a ceramic having a smaller thermal conductivity value than the material of the upper mold and the lower mold, heat radiation from the body mold is reduced, so that the inside of the cavity between the upper mold and the lower mold is reduced. Variations in temperature are reduced, and more accurate glass forming is enabled. As a specific material, the body mold may be made of silicon nitride, and the upper mold and the lower mold may be made of silicon carbide. The thermal conductivity of silicon carbide is generally 50 to 150 W / m · K, whereas that of silicon nitride is as small as 20 to 30 W / m · K.

  Numeral 6 denotes a heating means for high-frequency induction heating of the molding die A. A high-frequency induction coil 6b is wound around a ceramic cylindrical body 6a which is located outside the body die 1 of the molding die A. , The lower mold 3 is divided into an upper heating means 6c and a lower heating means 6d, which are independently controllable.

  A spiral groove 7 is formed on the inner peripheral surface of the cylindrical body 6a so as to face the outer peripheral surface of the body die 1. The cooling nozzle C is provided for rapid cooling of the molding die 1 and protection of the induction coil 6b from overheating. From the cylinder die 1 and the cylindrical body 6a.

  Outside the heating means 6, a cooling means 9 is provided so that the induction coil 6b is not damaged by heat from the mold A, and a water jacket 9a through which cooling water passes is arranged.

  In correspondence with the heating means 6, the upper mold 2 and the lower mold 3 of the molding die A are provided with heated parts 2b, 3b made of a material which can be easily induction heated. The heated portions 2b and 3b are preferably made of a material suitable for high-frequency induction heating, and more specifically, a ferromagnetic material containing a large amount of Fe, Ni, Co, or the like. In this embodiment, SUS410 is attached to the upper and lower dies 2 and 3 made of ceramics by thermal spraying to form the heated portions 2b and 3b.

  In the present embodiment, the heated portions 2b and 3b are provided in the upper mold 2 and the lower mold 3, but the heating function is exhibited even when the heated portion is provided in the body mold 1. As the temperature response to the mold 3 becomes worse, the clearance between the upper and lower molds 2 and 3 and the mold 1 becomes large due to the thermal expansion of the mold 1, and the eccentricity at the time of molding tends to deteriorate.

  The upper mold 2 and the lower mold 3 are provided with holes 2c, 3c extending in the axial direction to the vicinity of the cavities 2a, 3a of the upper and lower molds 2, 3, respectively. Temperature detecting means 8a and 8b composed of thermocouples for measuring the mold temperature are inserted.

  The molding process of the above-described glass lens molding apparatus will be described. First, a glass material is sandwiched between the cavities 2a and 3a between the upper mold 2 and the lower mold 3. In this state, as shown in FIG. 1, the body mold 1, the upper and lower molds 2 and 3, the heating means 6, and the cooling means 9 are assembled and assembled in the molding machine B.

  Next, an optimal high-frequency current is applied to the high-frequency induction coil 6b of the heating means 6 to heat the heated portions 2b and 3b of the mold A. This heating state is controlled based on the temperature data from the temperature detecting means 8a and 8b so as to obtain an optimum temperature rise curve. When the upper mold 2 and the lower mold 3 reach the optimum temperature, the molding machine B is driven to press the glass material. As for the press amount, the press operation is stopped when the press position or the press force reaches a preset press position, and the pressurized state is maintained. Thereafter, a nitrogen gas is supplied from the cooling nozzle C and flows through the spiral groove 7 on the outer peripheral surface of the body mold 1, cools the mold A, and releases the pressing force when a predetermined temperature is reached. To work. When the temperature reaches the removal temperature, one of the upper mold 2 and the lower mold 3 is removed, and the glass lens is removed.

(Embodiment 2)
FIG. 2 shows a second embodiment of the present invention in a configuration in which high-frequency induction heating is performed. In this case, the heating means 16 has an upper heating means 16c above the upper mold 12 and a lower heating means 16d having a lower mold. The heated portions 12b and 13b of the upper and lower molds 12 and 13 are formed on the upper surface of the upper mold 12 and the lower surface of the lower mold 13 respectively.

(Embodiment 3)
FIG. 3 shows a third embodiment of the present invention in a configuration for performing high-frequency induction heating. In this case, the heating means 26 moves in the vertical axis direction with respect to the body mold 21, the upper mold 22, and the lower mold 23. The heating state of the upper and lower dies 22, 23 can be changed by the vertical movement of the heating means 26. In addition, 22b and 23b are heated parts formed similarly to the heated parts 2b and 3b of FIG.

(Embodiment 4)
FIG. 4 shows a detailed embodiment of a lower mold for performing high-frequency induction heating (the same applies to the upper mold, and a description thereof will be omitted). The lower die 3 is provided with a groove 3d having a constant groove depth g on the outer periphery. A metal which is easy to induction heat, for example, SUS410 is sprayed and adhered to the groove 3d. At this time, the thickness t of the thermal spray coating 30 must be always smaller than the groove depth g.

  With the above configuration, the following operation is provided. Generally, when the material of the lower mold 3 and the material of the thermal spray coating 30 provided in the groove 3d are different, the thermal spray coating 30 is easily peeled off due to a difference in thermal expansion coefficient during heating. Even in such a case, by providing the groove 3d and forming the thermal spray coating 30 only in the groove 3d, the metal sprayed on the groove 3d is restrained, and peeling can be prevented.

Further, by making the thickness t of the thermal spray coating 30 smaller than the depth g of the groove 3d, even if the thermal spray coating 30 thermally expands during heating and the thickness changes from t to t + Δt, it is larger than the groove depth g. By not doing so, the operation in the axial direction can be performed smoothly without breaking the body mold (not shown), and as a result, good glass forming can be performed.

  The lower and upper thermal spray coatings 30 of the above configuration can be applied as the heated portions 3b, 23b, 2b, and 22b in FIGS. 1 and 3, and have the same structure as the heated portions 12b and 13b.

(Embodiment 5)
FIG. 5 shows a fifth embodiment of the glass lens forming apparatus according to the present invention. In particular, a configuration having a centering function will be described (the same components as those in FIG. 1 are denoted by the same reference numerals as in FIG. 1). ).

  In the present embodiment, a pressing block 100 is provided between the projection 5a of the movable part 5 of the molding machine and the upper surface of the upper mold 2, and the pressing force of the molding machine B is transmitted to the molding die A via this. . The pressure block 100 includes a disk-shaped pressure plate 100a that contacts the upper surface of the upper die 2, a disk-shaped alignment plate 100b that contacts the protrusion 5a of the movable portion 5, and a pressure plate 100a that is in contact with the pressure plate 100a. It comprises a connecting part 100c for connecting the parts 100b in parallel. The alignment plate 100b is supported by a plurality of steel balls 101 from the lower surface, and the steel balls 101 are urged upward by a spring 103 via a plate 102. Thereby, when the upper mold 2 is inserted into the body mold 1 or when the glass lens is formed, when the axis is misaligned, the pressing block 100 is moved in the horizontal direction and the squareness is misaligned. Can perform centering by rotating the pressing block 100, and perform high-precision and stable molding without depending on the machine precision such as the parallelism and the squareness of the pressing portion of the molding machine. I can do it.

(Embodiment 6)
A sixth embodiment of the present invention shown in FIGS.

  In FIG. 6, reference numeral 61 denotes a lower die made of silicon carbide, and 62 denotes a cylindrical object to be heated provided in the lower die 61, which is made of a metal material made of SUS420 for high-frequency induction heating. Reference numeral 63 denotes a columnar heated body provided in the lower mold 61 in the same manner as the heated body 62 and formed of the same metal material (SUS420), and both are arranged on the same axis as the lower mold 61. . In the present embodiment, the example in which the heated objects 62 and 63 are provided in the lower mold 61 is shown, but they may be provided in the upper mold, or may be provided in both the upper and lower molds as shown in FIG. In FIG. 7, upper and lower dies 61, 61 made of silicon carbide and having bodies to be heated 62, 63 are provided facing each other, and a cavity 65 for molding a glass lens is formed between the two. A body mold 64 also made of silicon carbide is provided to guide the upper and lower molds 61, 61. A high-frequency induction coil (heating body) 66 is provided so as to surround the upper and lower molds and the body mold, and a power supply unit to be energized, a mechanical unit for molding, and the like are arranged (not shown). When a high-frequency AC power supply is supplied to the high-frequency induction coil 66, magnetic flux alternating in the axial direction of the molding die is generated, and the heated bodies 62, 63 provided inside the upper and lower dies 61, 61 are heated to a high temperature. In the present embodiment, the objects to be heated 62 and 63 are installed in the vicinity of a glass material to be a lens and combined with an upper and lower mold made of silicon carbide having a high thermal conductivity to perform induction heating, so that the vicinity of the glass material can be reduced in a short time. Can be heated to a predetermined temperature around 600 ° C. Then, by measuring the temperature near the cavity 65 and controlling the high-frequency induction coil 66 based on the data, a highly accurate glass lens can be manufactured with high yield. In addition, since this heating raises the temperature of the cavity 65 through the heated members 62 and 63, unlike the conventional method in which the heating is performed by heat conduction from the outer peripheral portions of the upper and lower dies as in the conventional method. Since the temperature of the body mold 64 does not become higher than the temperature of the upper and lower molds 61 and 61, and the clearance between the body mold 64 and the body mold 64 does not expand, a lens with higher coaxiality can be formed.

  It should be noted that only one or both of the upper and lower dies 61, 61 may be provided with only the cylindrical heated object 62 or only the columnar heated object 63.

(Embodiment 7)
A seventh embodiment of the present invention shown in FIG. 8 will be described. In FIG. 8, reference numerals 71 and 72 denote upper and lower molds 74 made of silicon carbide, which are vertically opposed to each other to form a cavity 73 for molding a glass lens. Is a high-frequency induction coil (heating body) provided so as to surround the outer periphery of the forming die; and 76 is a circle provided coaxially in the upper and lower dies 71 and 72. It is a pillar-shaped object to be heated and is made of SUS420, which is a material that can be easily heated by induction. Reference numeral 77 denotes a cylindrical object to be heated provided coaxially with the upper and lower dies 71 and 72, which is also made of SUS420 and is arranged so as to surround the cavity 73. Reference numeral 78 denotes a cylindrical heating relaxation body coaxially and closely disposed inside the above-mentioned heated body 77, which is made of a material which is more difficult to conduct induction heating than the above-mentioned heated body 77, such as non-magnetic SUS316 or Heat-resistant alloys represented by Inconel, copper alloys, tungsten, cemented carbides, ceramics and the like are selected.

  In the above configuration, when a high-frequency AC power is supplied to the induction coil 75, a magnetic flux that alternates in the axial direction of the molding die is generated, and the heated body 76 provided inside the upper die 71 and the lower die 72 is heated. This heat is transmitted to the cavity 73 in which the glass material is placed, and when it reaches a predetermined temperature, it is pressed and formed. Here, paying attention to the temperature distribution in the cavity 73, the outermost periphery of the cavity 73 comes into contact with outside air, so that the temperature decreases, and a temperature gradient occurs in the radial direction of the cavity 73. Therefore, in the present embodiment, the heated body 77 is provided so as to surround the outer periphery of the cavity 73, and the heated body 77 generates heat by an alternating magnetic field similarly to the heated body 76, and also from the outer periphery of the cavity 73. Since the heating is performed, the temperature distribution in the cavity 73 can be made uniform, and the effect of shortening the temperature rise time as compared with the configuration of the sixth embodiment also occurs. Further, in the present embodiment, the heating relaxation body 78 is provided in contact with the inside of the heated body 77, but this is because the heated body 77 to be subjected to induction heating is heated from the surface by the surface layer effect of induction heating. In this case, the temperature on the outermost peripheral side of the cavity 73 is prevented from increasing, and the outer peripheral portion of the cavity 73 is heated by heat conduction.

  As described above, in the present embodiment, in addition to the configuration of the sixth embodiment, by providing the heated body 77 made of a material that is easily induction-heated so as to surround the cavity 73 of the upper and lower dies 71 and 72, By making the temperature distribution in 73 more uniform and increasing the temperature to a predetermined temperature at a high speed, molding with a faster cycle time is possible.

(Embodiment 8)
An eighth embodiment of the present invention shown in FIG. 9 will be described. The feature of this embodiment is that it has a plurality of cavities formed with the upper die and the lower die facing each other as compared with the configuration of the seventh embodiment. Hereinafter, only the lower mold will be described. In FIG. 9, reference numeral 81 denotes a lower die having a plurality of cavities 81a forming a molding surface of a glass lens with an upper die (not shown). Of the lower die 81 is heated by induction heating. Reference numeral 83 denotes a cylindrical object to be heated which is arranged so as to individually surround the plurality of cavities 81a and is made of a material which can be easily subjected to induction heating, and 84 is in close contact with the inner peripheral surface of the individual object to be heated 83. The cylindrical heat relaxation member is made of a material that is difficult to conduct induction heating, and its functions, specific materials, and the like are the same as those in the seventh embodiment. However, when power is supplied to an induction coil (not shown) arranged so as to surround the molding die including the upper and lower dies, as in the seventh embodiment, if there is a cavity on the central axis of the upper and lower dies, Even if a temperature gradient occurs in the cavity, the temperature distribution becomes symmetric in the radial direction. On the other hand, when the cavity is not on the center axis of the upper and lower molds as in the case of the present embodiment, the temperature gradient is different between the inside and the outside of the axis of the upper and lower molds in one glass molding surface. Will be. In such a temperature distribution state, a highly accurate glass molded lens cannot be produced with high yield. Therefore, in the present embodiment, in addition to the heated body 82, the heated body 83 and the heating relaxation body 84 are provided so as to surround the plurality of cavities 81a, respectively. The temperature gradient generated in the cavity can be corrected by the heated object 83. Further, there is an advantage that the time required for the temperature to reach the predetermined temperature is shortened.

  INDUSTRIAL APPLICABILITY The present invention is applicable not only to the molding of glass lenses but also to the field of molding precision plastic parts.

FIG. 1 is a schematic explanatory view of a glass lens forming apparatus according to a first embodiment of the present invention. It is a schematic explanatory view of a heating configuration of a glass lens forming device in a second embodiment of the present invention. It is a schematic explanatory view of a heating configuration of a glass lens forming apparatus in a third embodiment of the present invention. It is a schematic explanatory view of a glass lens forming device in a fourth embodiment of the present invention. It is a schematic explanatory view of a glass lens forming device in a fifth embodiment of the present invention. It is explanatory drawing of the principal part of the glass lens shaping | molding apparatus in 6th Embodiment of this invention, (a) is sectional drawing, (b) is an exploded perspective view. It is a schematic explanatory view of a glass lens forming device in a sixth embodiment of the present invention. It is a schematic explanatory view of a glass lens forming device in a seventh embodiment of the present invention. It is the schematic explanatory drawing of the glass lens shaping | molding apparatus in 8th Embodiment of this invention, (a) is a top view, (b) is sectional drawing.

Explanation of reference numerals

1, 11, 21 Body mold 2, 12, 22 Upper mold 2a Cavity 2b, 12b Heated part 2c Hole 3, 13, 23 Lower mold 3a Cavity 3b, 13b Heated part 3c Hole 4 Fixed part 4a, 4b, 4c Projection 5 Movable part 5a Projection 6, 16, 26 Heating means 6a Cylindrical body 6b High frequency induction coil 6c, 16c Upper heating means 6d, 16d Lower heating means 7 Spiral grooves 8a, 8b Temperature detecting means 9 Cooling means A Mold B Molding Machine C Cooling nozzles 61, 81 Upper die, Lower die 65, 73, 81a Cavities 62, 63, 76, 77, 82, 83 Heated body 78 Heat relaxation body

Claims (21)

An upper mold having one of the cavities forming the optical surface of the glass lens and having an upper end receiving a pressing force from a movable portion of the molding machine, and having the other of the cavity of the upper mold and supported by a fixed section of the molding machine. A molding die for a glass lens, comprising a lower mold and a body mold for holding the upper and lower molds so as to be relatively movable in the vertical direction, in proximity to the peripheral surface of the upper and lower molds; Heating means for high-frequency induction heating of a heated portion formed on the upper and lower molds of the mold, cooling means for cooling the mold located close to the heating means, and provided near the cavity of the mold. , A temperature detecting means for controlling the heating means and the cooling means, wherein the upper mold of the molding die is pressurized through the movable means of the molding machine and one projection, and the lower mold of the molding die is Is supported by the fixing means of the molding machine and three projections. Glass lens molding apparatus characterized in that it is. One projection provided between the movable part of the molding machine and the upper mold is positioned substantially on the central axis of the pressing machine, and three projections provided between the fixed part of the molding machine and the lower mold. The glass lens forming apparatus according to claim 1, wherein the glass lens forming apparatus is positioned so as to form a substantially equilateral triangle having an apex on a circumference of a circle centered on a pressing central axis of the forming machine. 2. The glass lens molding apparatus according to claim 1, wherein the upper mold of the molding die is configured to be capable of centering in a horizontal direction and a rotation direction. An upper mold having one of the cavities forming the optical surface of the glass lens and having an upper end receiving a pressing force from a movable portion of the molding machine, and having the other of the cavity of the upper mold and supported by a fixed section of the molding machine. A molding die for a glass lens, comprising a lower mold and a body mold for holding the upper and lower molds so as to be relatively movable in the vertical direction, in proximity to the peripheral surface of the upper and lower molds; A heating unit for high-frequency induction heating of a heated portion formed in a part of the upper and lower molds of the molding die, and a cooling unit for cooling the molding die positioned close to the heating unit; A glass lens forming apparatus characterized in that a material that is easily induction-heated is used for a portion to be heated of a mold, and a material that is difficult to induction-heat is used for a body mold. 5. The glass lens forming apparatus according to claim 4, wherein the upper and lower dies of the forming die are formed with a heated portion made of a material which is easily induction-heated on an outer peripheral portion thereof. 6. The glass lens forming apparatus according to claim 5, wherein a ceramic material is used for the upper mold and the lower mold, and a metal material that is easily induction-heated is sprayed on the surface. 5. The glass lens forming apparatus according to claim 4, wherein a groove is provided on the outer periphery of the upper mold and the lower mold, and a metal material which is easily induction-heated is arranged in the groove. 8. The glass lens forming apparatus according to claim 7, wherein the depth of the groove formed in the upper mold and the lower mold is larger than the thickness of the metal material provided in the groove. The heated part of the molding die subjected to the induction heating is provided at an upper part of the upper mold and a lower part of the lower mold, and a heating means is located opposite to the heated part. Glass lens molding equipment. 5. The method according to claim 1, wherein the heating means is provided with an upper heating means for heating the upper mold and a lower heating means for heating the lower mold independently so that the temperature can be controlled separately. The glass lens forming apparatus as described in the above. The glass lens forming apparatus according to claim 1, wherein the heating unit moves in a vertical direction to change a heating state of the upper mold and the lower mold. The heating means winds the high-frequency induction coil around the cylindrical body, forms a spiral groove on the inner peripheral surface facing the outer periphery of the body mold, and cools the mold by flowing gas through the groove. The glass lens forming apparatus according to claim 1, wherein: 2. A glass lens forming apparatus according to claim 1, wherein one or both of the upper mold and the lower mold is provided with a hole drilled to a position close to the cavity, and the temperature detecting means is arranged in the hole. . The glass lens forming apparatus according to claim 1, wherein an axial length of the barrel of the mold is at least three times an inner diameter of the barrel. 5. The glass lens forming apparatus according to claim 4, wherein the thermal conductivity of the barrel of the forming die is smaller than that of the upper and lower dies. In order to form the cavity of the glass lens, a heated body made of a material that is easily induction-heated is disposed inside one or both of the upper mold and the lower mold that are opposed to each other, and the heated body is subjected to high-frequency induction heating. A glass lens forming apparatus characterized in that the glass lens in the cavity is formed by heat by the heat conduction of the object to be heated. 17. The glass lens forming apparatus according to claim 16, wherein the upper mold and the lower mold are made of ceramic, and the object to be heated provided inside is made of a magnetic material containing any of iron, nickel and cobalt. 17. The glass lens forming apparatus according to claim 16, wherein the object to be heated is provided so as to surround the cavity. The object to be heated is provided on a side far from the cavity, and a heating moderator made of a material that is harder to induction heat than the object to be heated is provided on a side closer to the cavity. 17. The glass lens forming apparatus according to item 16. 17. The glass lens forming apparatus according to claim 16, wherein an object to be heated is provided in each of the upper mold and the lower mold having a plurality of cavities. 21. The glass lens forming apparatus according to claim 20, wherein a heated body that heats the entire plurality of cavities is provided.

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