JP2007001282A - Molding die and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding die which can increase the supporting rigidity of an insert. <P>SOLUTION: This molding die 1 is used for molding a finished product in a cavity C formed between a first mold 100 and a second mold 200. The first mold 100 comprises an insert 110 which has a part of a cavity surface Ca to one end side, a body member 120 which retains the insert 110 from outside and a plurality of spherical bodies 130 which are interposed between the insert 110 and the body member 120 to align the insert 110. The spherical bodies 130 are tightly packed between the insert 110 and the body member 120. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a molding die and a manufacturing method thereof.

  A mirror frame, which is a member that supports an optical system such as a digital camera or a telephoto lens, has a great influence on the accuracy of the optical axis of the optical system, and therefore requires extremely high processing accuracy. Also, since the accuracy of the optical axis is a particularly important matter for product performance and quality, for example, when using 10 lenses as an optical system, a lens frame is manufactured so that one of them can be finely adjusted. In addition, the final adjustment of the optical axis is generally performed by finely adjusting the one lens. Recently, a small lens frame manufactured by plastic molding is widely used as a lens frame for supporting an optical system such as a film camera with a lens or a mobile phone with a camera. Furthermore, the lens itself constituting the optical system is formed by plastic injection molding, and the accuracy of the optical axis is very important in manufacturing such a lens.

  For example, as shown in FIG. 3, a mold is formed between the first mold 600 and the second mold 700 as a molding mold capable of manufacturing a product with high accuracy. There is known a molding die 500 for injection molding (see, for example, Patent Document 1). The first mold 600 includes a nest 610 having a cavity surface 610a, a body member 620 that holds the nest 610 from the outside, and has a convex taper portion 621 on the end surface on the second mold 700 side. And a ball bearing 630 interposed between the body member 620 and the body member 620. The second mold 700 includes a nest 710 having a cavity surface 710a, a body member 720 that holds the nest 710 from the outside and has a concave taper portion 721 on the end surface on the first mold 600 side, and a nest And a ball bearing 730 interposed between the main body member 720 and the main body member 720.

Such a mold interposes the nest 610 and the main body member 620 and the nest 710 and the main body member 720 by interposing the ball bearings 630 and 730, and the convex taper portion 621 and the concave taper portion 721 perform the first alignment. Centering of the mold 600 and the second mold 700 is performed.
Japanese Patent Laying-Open No. 2003-231159 (paragraphs 0020-0029, FIG. 1)

  The conventional molding die 500 is configured to remove the product from the cavity by moving the insert 610 when the mold is opened. Therefore, in the conventional molding die 500, the ball bearings 630 and 730 are configured from the plurality of spherical bodies and the retainer case so that the adjacent spherical bodies are not rubbed and worn when the insert 610 is moved. In addition, the spherical bodies are held apart from each other by the retainer case.

  However, in such a conventional molding die 500, the number of spherical bodies that can be installed is limited by the amount of retainer cases interposed between the spherical bodies. The support rigidity of the inserts 610 and 710 with respect to the body members 620 and 720 increases as the number of spherical bodies supporting the inserts increases. However, in the conventional molding die 500, since there is a retainer case, the support rigidity of the inserts 610 is increased. There is a problem that the value cannot be increased beyond a certain level. If the support rigidity of the insert 610 is small, the insert 610 moves during injection molding, causing a problem that the product cannot be accurately molded.

  Further, since the conventional molding die 500 is configured to take out the product from the cavity by protruding the insert 610 from the main body member 620 when the mold is opened, the insert 610 moves when the mold is clamped. For this reason, a gap S was necessary. For this reason, the distance from the cavity surface 610a of the insert 610 to the support point of the insert 610 (the spherical body on the most end side of the ball bearing) increases, the support rigidity of the insert 610 decreases (the amount of deflection increases), and the accuracy of the product There was a problem that decreased.

  Furthermore, in the conventional molding die 500, since the number of spherical bodies that can be placed between the spherical bodies is limited, the heat transfer path between the insert 610 and the main body member 620 is also limited. Is done. For this reason, there has been a problem that the increase in the nesting temperature due to the molten resin cannot be sufficiently suppressed, and the molding cycle becomes long.

  This invention is made | formed in view of this problem, and makes it a subject to provide the metal mold | die for manufacturing which can enlarge the support rigidity and heat transfer rate of a nest | insert, and its manufacturing method.

  A molding die according to the present invention is a molding die for forming a cavity between a first mold and a second mold, and molding a product in the cavity. The mold 1 includes a nest having a part of a cavity surface on one end side, a main body member that holds the nest from the outside, and a nest interposed between the nest and the main body member to align the nest. A plurality of spherical bodies, wherein the plurality of spherical bodies are closely packed between the insert and the main body member.

According to this configuration, since a plurality of spherical bodies are closely packed between the nest and the main body member, the support rigidity of the nest can be improved as compared with a conventional molding die having a retainer case. Can do.
Furthermore, according to this configuration, since a plurality of spherical bodies are closely packed between the nest and the main body member, the number of heat transfer paths between the nest and the main body member is increased. Therefore, the nesting temperature can be controlled more quickly.
Here, the state in which “the plurality of spherical bodies are closely packed between the nest and the main body member” means, for example, that the nest and the main body member are formed only by the plurality of spherical bodies without using a retainer case or a spacer. The state where the space between is filled.

  Further, the second mold is not particularly limited, and may be composed of a nest and a main body member like the first mold, or may be composed of a single member without being divided. May be.

  Further, it is preferable that at least one of the first mold and the second mold includes an extruding pin installed so as to protrude from the cavity surface.

According to such a configuration, since it is not necessary to move the nest to take out the molded product, the spherical bodies are not rubbed and worn. Therefore, even if the retainer case and the spacer are omitted, the shape (diameter) of the spherical body does not change, and the nest can be accurately placed at a predetermined position. Further, since the insert and the main body member are not fixed as in “shrink fitting” or the like, it is easy to disassemble and perform maintenance.
Further, since it is not necessary to provide a gap for the nest to move (see S in FIG. 3), the distance between the cavity surface formed at one end of the nest and the fulcrum of the nest is shortened, and the support rigidity of the nest is increased. improves.

  In addition, it is preferable that the plurality of spherical bodies are packed between the nest and the main body member in a state of receiving a preload.

  According to such a configuration, since the nest can be supported with a stronger support force, the support rigidity of the nest can be further increased. In order to apply preload to the spherical body, a metallic spherical body having a slightly larger diameter than the size of the gap between the main body member and the insert may be used. If it does in this way, a spherical body will be packed while elastically deforming any of a main body member, a nest | insert, and a spherical body, and the restoring force will act as a preload.

  The nest includes a columnar portion having a part of the cavity surface on one end side, and the main body member opens on one end side of the main body member and fits with one end side of the columnar portion. And a large hole portion that opens to the other end side of the main body member and communicates with the other end side of the narrow hole portion and loosely fits to the other end side of the columnar portion, and the plurality of spherical bodies include: It is preferable to configure so that it is packed tightly between the outer peripheral surface of the columnar portion and the inner peripheral surface of the thick hole portion.

According to such a configuration, since the plurality of spherical bodies are closely packed between the outer peripheral surface of the columnar part and the inner peripheral surface of the thick hole part, the support rigidity of the nest can be improved.
Further, since one end side of the nest is fitted into the narrow hole portion of the main body member and the other end side of the nest is loosely fitted into the thick hole portion of the main body member, it is possible to prevent the spherical body from dropping off. At the same time, when the product is molded, the molding material filled in the cavity can be prevented from entering the space between the other end side of the insert and the thick hole portion.

  In addition, the cross-sectional shape of the columnar part is not particularly limited, and may be, for example, a columnar shape or a prismatic shape.

  Moreover, it is preferable that the molding die described above is manufactured by a method in which a spherical body is closely packed between the main body member and the insert after the main body member is heated and expanded.

  According to such a method, after the main body member is heated and expanded, the spherical body is densely packed between the main body member and the nest, so that the gap between the main body member and the nest is, for example, from the gap Large spheres can be easily packed. Further, when the main body member expanded by heating returns to the normal temperature and contracts, a preload is applied to the spherical body. As a result, the support rigidity of the insert can be further increased.

According to the present invention, since the plurality of spherical bodies are closely packed between the insert and the main body member, the support rigidity of the insert can be improved. Therefore, the product can be molded with high accuracy.
Further, according to the present invention, since a plurality of spherical bodies are closely packed between the nesting body and the main body member, compared with the case where the retainer is interposed between the sphere bodies, As a result, the nesting temperature can be controlled with higher accuracy.

  The best mode for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, a case where the present invention is applied to manufacture of a lens frame will be described.

First, the configuration of the molding die according to this embodiment will be described.
In the drawings to be referred to, FIG. 1 is a cross-sectional view of a molding die according to the present embodiment.

  As shown in FIG. 1, the molding die 1 is formed by forming a cavity C between a first die 100 and a second die 200 and molding a lens frame K as a product in the cavity C. It is. As shown in FIG. 1B, the lens frame K is a member that holds a plurality of lenses (not shown) constituting the optical system, and is formed with a stop s. In the present embodiment, in the configuration of the lens frame K, a portion on one end side (the right side in FIG. 1) from the stop s is formed by a part of the cavity C formed in the second mold 200, and from the stop s. The portion on the other end side (left side in FIG. 1) is formed by a part of the cavity C formed in the first mold 100. The molding die 1 according to the present embodiment is a die that can mold the lens frame K with high accuracy so that the optical axes of lenses installed on both sides of the stop s coincide.

  As shown in FIG. 1A, the first mold 100 includes a nest 110 having a part of a cavity surface (hereinafter referred to as “cavity surface Ca”) at the tip, and a main body into which the nest 110 is fitted. It is comprised from the member 120 and the metal spherical body 130 interposed between the nest | insert 110 and the main-body member 120. FIG.

  The nesting 110 is a metal member configured as a separate part from the main body member 120 in order to form the edge of the lens frame K sharply. As shown in FIG. A columnar portion 112 formed in a circular shape in a sectional view and extending from a central portion on one end side of the nested body 111 is configured.

  The nesting body 111 is a part that is attached to a template or the like of an injection molding apparatus (not shown), and has a larger diameter than a thick hole portion 122 of the body member 120 described later.

  The columnar portion 112 is a portion that fits into the main body member 120. In the present embodiment, as shown in FIG. 1B, a cylindrical thin-diameter portion 114 having a cavity surface Ca on one end side, and this The cylindrical large-diameter portion 115 is formed continuously with the other end side of the small-diameter portion 114 and has a larger diameter than the small-diameter portion 114.

  The main body member 120 is a metal member for holding the insert 110 from the outside, and as shown in FIG. 1B, has a cylindrical shape with a hollow portion at the center thereof. The hollow part of the main body member 120 includes a narrow hole part 121 into which the small diameter part 114 formed on one end side of the columnar part 112 of the nest 110 is fitted, and a thick hole part 122 loosely fitted to the large diameter part 115 of the nest 110. Is configured. Further, a convex taper portion 123 having a truncated cone shape is provided on the end surface on one end side of the main body member 120 so that the second member 200 can be centered.

  The narrow hole 121 is formed to be approximately the same as or slightly larger than the narrow diameter portion 114 of the insert 110. Specifically, the narrow hole portion 121 is preferably formed larger than the small diameter portion 114 by a diameter of about 10 to 30 μm (radius of about 5 to 15 μm), and a diameter of about 10 to 20 μm (radius of about 5 to 10 μm) is larger. More preferably, it is formed. Further, one end side of the narrow hole portion 121 is open to a surface on one end side of the main body member 120, and when the small diameter portion 114 of the nest 110 is inserted into the narrow hole portion 121, The formed cavity surface Ca is exposed to one end surface of the main body member 120. A cavity surface Cb is formed on one end side of the narrow hole portion 121.

  The thick hole portion 122 has a gap that is the same as or slightly smaller than the diameter of the spherical body 130 around the large diameter portion 115 when the large diameter portion 115 of the insert 110 is inserted into the thick hole portion 122. It is formed in an empty size (inner diameter). In addition, the other end side of the thick hole portion 122 opens to the end surface on the other end side of the main body member 120 so that the columnar portion 112 of the insert 110 can be inserted. One end side of the thick hole portion 122 communicates with the other end side of the narrow hole portion 121.

  Further, an extrusion pin E for extruding the molded product from the cavity C is provided on the end face on one end side of the main body member 120. The extruding pin E is composed of two pins connected at the other end and an elastic body that urges the two pins toward the second mold 200, and one of the pins is a second pin when the mold is clamped. It abuts on the other end side of the mold (see FIG. 1A), and the other pin protrudes from the cavity surface when the mold is opened (see FIG. 1B). The extrusion pin E is disposed in a recess formed on the end surface on one end side of the main body member 120, and two members each having a through hole through which the pin is inserted are fitted into the opening of the recess.

  The spherical body 130 is a metal sphere that is interposed between the main body member 120 and the nest 110 to support and align the nest 110. The spherical body 130 is closely packed in the gap between the large diameter portion 115 and the thick hole portion 122. In other words, the gap between the large diameter portion 115 and the thick hole portion 122 is filled only with the plurality of spherical bodies 130. Thereby, the nest | insert 110 will be supported by many support points compared with the case where a retainer case and a spacer interpose between spherical bodies 130. FIG. Therefore, the support rigidity of the nest | insert 110 with respect to the main body member 120 improves.

The spherical body 130 is formed to have a diameter that is substantially the same as or slightly larger than the size of the gap between the large diameter portion 115 and the large hole portion 122. Specifically, it is preferable to use a spherical body 130 whose diameter is about 1 to 6 μm larger than the gap interval. In this way, the spherical body 130 is packed in the gap between the large diameter portion 115 and the thick hole portion 122 in an elastically crushed state, and the restoring force of the spherical body 130 acts as a preload. Thus, the nest 110 is more firmly supported. The outer peripheral surface of the large diameter portion 115 and the inner peripheral surface of the thick hole portion 122 are also elastically deformed by coming into contact with the spherical body 130, and the restoring force acts as a preload.
Further, when the spherical bodies are closely packed, the spherical bodies come into contact with each other and hardly move, and there is an advantage that the support rigidity is improved.

  Further, since the large-diameter portion 115 of the nest 110 is formed to have substantially the same length as the thick hole portion 122 of the main body member 120, when the nest 110 is fitted into the main body member 120, There is no gap between the end surface on one end side and the end surface on one end side of the thick hole portion 122. Therefore, the spherical body 130 can be packed up to the vicinity of the end face on one end side of the thick hole portion 122. Thereby, the support rigidity of the nest | insert 110 further improves.

  As shown in FIG. 1A, the second mold 200 includes a nest 210 having a part of a cavity surface (hereinafter referred to as “cavity surface Cb”) at the tip, and a main body into which the nest 210 is fitted. And a member 220.

  As shown in FIG. 1B, the nest 210 includes a nest main body 211 and a columnar section 212 having a circular cross section extending from the other end side (first mold 100 side) of the nest main body 211. It is configured. The columnar portion 212 has a truncated cone shape (tapered shape) and tapers toward the other end side. A part of the cavity surface (hereinafter referred to as “cavity surface Cc”) is formed on the other end side of the columnar portion 212. Further, the insert 210 includes a sprue SP and a gate G that communicate one end side of the insert body 211 with the cavity surface Cc.

  The main body member 220 is a member into which the columnar portion 212 of the insert 210 is fitted, and is a member that plays a role of adjusting the positional relationship between the first mold 100 and the second mold 200. The main body member 220 has a substantially cylindrical shape, and a flange is formed on the other end side. As shown in FIG. 1, the hollow portion of the main body member 220 includes, from one end side, a thick hole portion 222 into which the columnar portion 212 of the insert 210 is fitted and a cavity surface Cc formed on the other end side of the columnar portion 212. A narrow hole portion 221 to be externally fitted and a concave taper portion 223 to be fitted to the convex taper portion 123 of the first mold 100 are configured. The thick hole portion 222 is formed in a tapered space that tapers toward the other end side, so that the columnar portion 212 of the inserted nest 210 can be aligned. In addition, the concave taper portion 223 is formed in a tapered space that tapers toward one end side so that the first mold 100 and the second mold 200 can be aligned. The narrow hole portion 221 is formed to have a smaller diameter than the thick hole portion 222, and a cavity surface Cd is formed on the inner peripheral surface thereof.

  As shown in FIGS. 1A and 1B, the molding die 1 is configured to fit the convex taper portion 123 of the first die 100 and the concave taper portion 223 of the second die 200. As a result, alignment is made. Further, by combining the first mold 100 and the second mold 200, the cavity surfaces Ca, Cb, Cc, Cd are connected to form the cavity C.

  Next, a method for closely packing the spherical body 130 between the insert 110 and the main body member 120 will be described. FIG. 2 is a cross-sectional view showing step by step a procedure for packing a spherical body between the insert and the main body member.

  First, as shown in FIG. 2A, the columnar portion 112 of the nest 110 is placed on the body member so that the one end side 115a of the large diameter portion 115 and the other end side 122a of the thick hole portion 122 are at the same depth position. It is inserted into 120 thick holes 122. Then, the spherical body 130 is disposed in a gap T formed between one end side of the large diameter portion 115 and the other end side of the thick hole portion 122. At this time, since the gap T is formed to be slightly narrower than the diameter of the spherical body 130, the spherical body 130 does not enter the gap T but is caught near the entrance of the gap T. Become.

  Next, as shown in FIG. 2B, the columnar portion 112 of the nest 110 is pushed toward the main body member 120 by an amount corresponding to the diameter of the spherical body 130. At this time, when the spherical body 130 is pushed toward the one end side together with the nest 110, the spherical body 130 is caught in the gap T and enters the gap T while rotating or sliding while elastically deforming. It will be followed.

  When the spherical body 130 enters the gap T by the diameter, the next spherical body 130 is arranged in the vicinity of the entrance of the gap T as shown in FIG.

  Then, by pressing the columnar portion 112 (see FIG. 2B) and arranging the spherical bodies 130 (see FIG. 2C) a plurality of times, the plurality of spherical bodies 130 are densely packed in the gap T. It can be packed (see FIG. 2D).

  In addition, it is preferable to pack the spherical body 130 to the back of the gap T by pushing the spherical body 130 using a dedicated jig. As a dedicated jig, for example, two jigs formed in a semicircular shape are fitted in the vicinity of the other end side of the large-diameter portion 115 to form a ring shape, and this is moved to one end side along the large-diameter portion 115. Therefore, it is preferable to push the spherical body 130 into the gap T.

  As another method, the spherical body 130 may be packed in the gap T after the body member 120 is heated and expanded. In this way, the gap T between the main body member 120 and the nest 110 (large diameter portion 115) is increased, and the spherical body 130 having a diameter larger than the gap T in the normal temperature state can be easily packed in the gap T. Further, as the temperature of the main body member 120, the insert 110, and the spherical body 130 becomes uniform, preload (preload) acts on the spherical body 130. That is, according to this method, preload can be easily introduced.

  In addition, if the size of the gap T when the main body member 120 is expanded is sufficiently larger than the spherical body 130, the spherical body 130 can be densely packed up to the full end (to the back) of the thick hole portion 122. . Accordingly, the nest 110 is supported at a position close to the cavity surface Ca, and the support rigidity of the nest 110 is improved.

  As a method for heating the main body member 120, for example, a method in which an electric heater is embedded in the main body member 120, a method in which an electric heating mat is wound around the main body member 120, or a non-contact method using infrared rays or the like. And a method of heating the main body member 120 in a constant temperature bath. In particular, a method using an electric heater or an electric heating mat is preferable because it can work while keeping the temperature of the main body member 120 at a high temperature.

  In addition, since the gap T increases as the temperature difference between the nest 110 and the main body member 120 increases, it is preferable to perform this operation with the temperature of the nest 110 as low as possible (without increasing the temperature). In addition, since the diameter of the spherical body 130 becomes smaller as the temperature of the spherical body 130 becomes lower, it is preferable to perform this operation with the temperature of the spherical body 130 as low as possible (without increasing the temperature). Note that the temperatures of the nest 110 and the spherical body 130 may be positively decreased using a cold / hot bath or a refrigerant (cold water or the like).

  The best mode for carrying out the present invention has been described in detail with reference to the drawings. However, the present invention is not limited to the embodiment, and appropriate modifications can be made without departing from the gist of the present invention. Is possible.

  For example, in the present embodiment, an example in which the present invention is applied to a mold for manufacturing the lens frame K has been described. However, the present invention is not limited to this, and other optical components such as a plastic optical lens or the like are used. You may apply to the metal mold | die for manufacturing a precision component.

  In the present embodiment, the columnar portion 112 of the nest 110 is composed of the small-diameter portion 114 and the large-diameter portion 115. However, the present invention is not limited to this, and the columnar portion 112 is not limited to the narrow hole of the main body member 120. You may comprise by the same fixed thickness as the part 121. FIG. In such a case, it is preferable to use a spherical body having a size (diameter) slightly larger than the difference between the radius of the thick hole portion 122 and the radius of the narrow hole portion 121.

  In the present embodiment, as shown in FIGS. 1 and 2, the spherical bodies 130 are regularly packed in the gap between the nest 110 and the main body member 120, but this is not a limitation. The spherical body 130 may be packed irregularly.

  The arrangement (arrangement) of the spherical bodies 130 is not particularly limited. For example, the spherical bodies 130 adjacent to each other in the axial direction of the mold may be arranged in a so-called square lattice shape so that the centers thereof are parallel to the axial direction of the mold. Moreover, you may arrange | position so-called zigzag so that the center of the spherical bodies 130 adjacent to the axial direction of a metal mold | die may shift | deviate in the circumferential direction. Note that the spherical bodies 130 can be packed more densely in a staggered arrangement than in a square lattice. The filling rate of the gap T is preferably 20% or more, and more preferably 50% to 65%.

It is sectional drawing of the metal mold | die for shaping | molding which concerns on this embodiment, (a) shows the state at the time of mold clamping, (b) shows the state at the time of a mold opening, respectively. It is sectional drawing which showed in steps the procedure which stuffs a spherical body between a nest | insert and a main-body member. It is sectional drawing of the conventional metal mold | die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molding die 100 1st metal mold | die 110 Nesting 120 Main body member 130 Spherical body 200 2nd metal mold | die 210 Nesting 220 Main body member C Cavity

Claims (4)

A mold for forming a cavity between a first mold and a second mold and molding a product in the cavity,
The first mold is
A nest having a part of the cavity surface on one end side;
A body member for holding the insert from the outside;
A plurality of spherical bodies that interpose between the nest and the body member and align the nest;
The molding die, wherein the plurality of spherical bodies are closely packed between the insert and the main body member.   2. The molding die according to claim 1, wherein the plurality of spherical bodies are packed between the insert and the main body member in a state of receiving a preload. The nesting includes a columnar part having a part of the cavity surface on one end side,
The main body member opens to one end side of the main body member and fits into one end side of the columnar portion, and opens to the other end side of the main body member and to the other end side of the narrow hole portion. A thick hole part loosely engaged with the other end side of the columnar part,
The molding metal according to claim 1 or 2, wherein the plurality of spherical bodies are closely packed between an outer peripheral surface of the columnar portion and an inner peripheral surface of the thick hole portion. Type. A method for producing a molding die according to claim 1, wherein:
After the main body member is heated and expanded, a spherical body is closely packed between the main body member and the insert.

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