JP2651274B2 - Press molding die structure - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to the structure of a press mold, and more particularly to the structure of a press mold for maintaining good thickness accuracy of a molded product and maintaining a long mold life. About. INDUSTRIAL APPLICABILITY The present invention can be suitably applied to, for example, a mold for quickly manufacturing an optical element having an optical function surface from a molding material by pressing.

[Problems to be Solved by Related Art and Invention] In recent years, a material for optical element molding, for example, a glass blank preformed to a certain shape and surface accuracy has been housed in a molding die having a predetermined surface accuracy. A method for producing an optical element having a high-precision optical function surface by press-forming under heating so that post-processing such as grinding and polishing is not required has been developed.

In this press molding method, at least a pair of molding die members are arranged so as to be relatively reciprocable in a facing direction, and a molding material is placed in a cavity formed by a member including at least the pair of molding members. introducing, as a non-oxidizing atmosphere of nitrogen atmosphere for example atmosphere for preventing oxidation of the mold members, moldable temperature e.g. molding material by heating the mold member to a temperature at which a 10 ⁸ to 10 ¹² poises, suitably close the mold Press for a time to transfer the surface shape of the mold member to the surface of the molding material,
Then, the temperature of the mold member is cooled to a temperature sufficiently lower than the glass transition temperature of the molding material, the pressing pressure is removed, and the mold is opened to take out the molded optical element.

According to the press molding method as described above, it is possible to manufacture an aspherical lens or the like, which was conventionally extremely expensive, at a relatively low cost.

By the way, in the press die, the thickness of the molded product (that is, the thickness in the direction corresponding to the facing direction of the pair of molding die members) is set such that the pair of molding die members face each other. The position is set by the movement stop position at the time of pressing while moving relatively. Conventionally, a sleeve-shaped body member is used for setting the stop position, and a pair of mold members are directly or indirectly abutted against the body member, or one of the mold members is attached to the body member. In this case, the thickness of the molded product is set by fixing the position of the molded product with respect to the mold member and abutting the other mold member against the body mold member.

Such an example is disclosed in, for example, JP-A-61-174127 and JP-A-62-203235.

However, in the above-described conventional example, the abutment between the body-shaped member and at least one of the pair of mold members is performed using the entire end surface of the body-shaped member. If foreign matter such as dust from the molding material adheres,
In the press, an appropriate stop position cannot be obtained due to the presence of the foreign matter between the abutting surfaces, and especially after repeated use, a large amount of the foreign matter remains, resulting in a significant decrease in stopping accuracy or the abutting surface due to the foreign matter. However, there is a drawback that the frequency is high such that the life of the mold is shortened due to damage to the mold.

In view of the above problems of the prior art, the present invention always accurately sets the stop position of relative movement between a pair of mold members during pressing, thereby improving the thickness accuracy of a molded product. It is an object of the present invention to provide a structure of a press-forming die capable of maintaining a long life of the die.

[Means for Solving the Problems] According to the present invention, there is provided a press forming method in which an upper die member and a lower die member are arranged in a sleeve so as to be slidable in the longitudinal direction of the sleeve, respectively. In the structure of the mold, there is provided means for restricting movement of the lower mold member relative to the sleeve in a direction away from the upper mold member, and a ring member is attached to an upper end surface of the sleeve. Has at least three through holes in the longitudinal direction of the sleeve. Pins of the same length are removably inserted into each of the through holes. The structure of a press-molding die, characterized in that an abutment surface to be brought into contact with a pin is formed.

In the present invention, there is a mode in which the through holes are arranged at equal intervals in a circumferential direction of the ring member.

Further, in the present invention, there is a mode in which a projection on the center axis in the vertical direction of the sleeve is formed on the upper part of the upper die member, and a pressing force is applied to the projection from above.

Further, in the present invention, there is a mode in which both the upper end surface of the sleeve and the abutting surface of the upper mold member are in a plane orthogonal to the longitudinal direction of the sleeve.

Example An example of the present invention will be described below with reference to the drawings. The following examples are applied to press molding of an optical lens.

FIG. 1 (a) is a longitudinal sectional view showing a first embodiment of the structure of the press mold according to the present invention, and FIG. 1 (b) is a partially omitted BB sectional view thereof. FIG. 1A corresponds to a cross section taken along line AA in FIG. 1B.

In these figures, reference numeral 2 denotes a lower mold member, the upper surface of which is finished to a required surface accuracy in order to transfer-form the first optical functional surface of the lens. This surface may be aspheric. Reference numeral 4 denotes an upper mold member, the lower surface of which is finished to a required surface accuracy in order to transfer and form the second optical function surface of the lens. This surface may be aspheric. These two mold members 2 and 4 constitute a pair of mold members.

Reference numeral 6 denotes a sleeve, by which the lower mold member 2 and the upper mold member 4 are supported so as to be vertically movable. The side of the sleeve 6 is formed with an opening 7 for introducing a molding material and removing a molded product.

A support plate 8 is fixed to a lower portion of the sleeve 6. The lower die member 2 is restricted from moving downward by the support plate 8. Although not shown,
The support plate 8 is mounted on a molding machine.

10 is a holder for holding the upper mold member 4,
The upper mold member 4 can be engaged with the upper flange portion. Also,
Reference numeral 12 denotes a rod for pressing the upper die member 4 downward, and the pressing rod is provided on the molding machine side. still,
On the upper part of the upper die member 4, a projection 5 is formed on the central axis in the vertical direction of the sleeve 6, and a pressing force is applied to the projection from above.

A ring member 24 is mounted on a horizontal upper end surface of the sleeve 6.

 G is a molding material.

FIG. 1 (b) is a first view in which the upper mold member 4 is not shown.
FIG. 3B is a cross-sectional view taken along the line BB in FIG. 1A, and as shown therein, three pins 20a, 20b, and 20c are removably inserted into three through holes formed in the ring member 24. Have been. These three pins are arranged at positions shifted by 120 degrees around the vertical center of the sleeve, and their upper ends are located in a horizontal plane. The pins 20a to 20c are thick enough to withstand the pressing pressure, and do not buckle during pressing.

As shown in FIG. 1 (a), a flange projecting above the upper end surface of the sleeve 6 is formed on the upper part of the upper die member 4, and the lower surface thereof is abutting surface 22.
It has been. The butting surface is also located in a plane perpendicular to the up-down direction (ie, a horizontal plane).

 Next, the operation of this embodiment will be described.

FIG. 2 is a cross-sectional view showing a state when the molding material G is introduced into the mold before pressing in the present embodiment.

That is, by lifting the pressing rod 12 and the holder 10 upward, the upper die member 4 is held by the holder 10 and moved upward. Then, in a state where the molding material G is vacuum-sucked by the suction portion 32 provided at the tip of the transfer arm 30,
The arm 30 is moved in the horizontal direction, and the suction part 32 is inserted into the mold from the opening 7 of the sleeve 6 and further moved slightly downward to release the suction. Place on top of member 2. Then, the arm 30 is moved in the horizontal direction, and the suction section 32 is retracted out of the mold.

FIG. 1 (a) shows a pressed state, in which a pressing rod is provided.
By moving the holder 12 and the holder 10 downward, the upper protrusion of the upper mold member 4 is pressed downward by the pressing rod 12. At this time, the holding of the upper mold member 4 by the holder 10 is released, and the lower mold member 2 is fixed in position by the downward movement of the support plate 8 being restricted. Thus, the molding material G placed between the lower mold member 2 and the upper mold member 4 is pressed, and the abutment surface 22 of the upper mold member 4 is abutted against the pins 20a to 20c to move downward. Of the molded product is set, thereby setting the thickness of the molded product.

The removal of the molded product is performed by a method similar to the introduction of the molding material.

That is, by lifting the pressing rod 12 and the holder 10 upward, the upper die member 4 is held by the holder 10 and moved upward. Then, the transfer arm 30 is moved in the horizontal direction, the suction section 32 is inserted into the mold from the opening 7 of the sleeve 6, and the suction section 32 is further moved slightly downward to suction the molded product. Then, the arm 30 is moved slightly upward, and then moved in the horizontal direction, so that the suction portion 32 is retracted out of the mold.

In the present embodiment as described above, since the movement of the upper die member 4 is restricted by abutting against the abutting surfaces 22 of the upper ends of the pins 20a to 20c having the lower ends abutting on the upper end surface of the sleeve 6, the abutment is performed. The area is small, and there is virtually no foreign matter such as dust between them. Therefore, the thickness of the molded product is set very accurately, and even after repeated molding, the abutting portion is hardly damaged, the accuracy is maintained well, and the mold life is maintained long. Can be.

Further, the pins 20a to 20c need only be simply inserted into the through holes of the ring member 24, so that the pins 20a to 20c can be easily attached and removed, and can be easily removed and repaired when the pins are repaired.

Further, the upper end surface of the sleeve 6 and the abutting surface 22
Is a plane orthogonal to the direction of movement of the upper mold member 4, so that the positions of the pins 20a to 20c in the horizontal plane need not be strictly set.
A sufficiently high molded product wall thickness accuracy can be obtained.

In addition, on the upper part of the upper die member 4, a projection 5 is formed on the vertical axis of the sleeve 6, and a pressing force is applied to the projection from above by the pressing rod 12, so that
Even if the pressing rod is displaced in the horizontal direction, a uniform pressing force can be applied, and a uniform force can be applied to each of the pins 20a to 20c.

In the present embodiment, since the lower mold member 2 is movable in the vertical direction with respect to the sleeve 6, even if the molded product shrinks in the cooling process after pressing, the lower mold member 2 follows. Therefore, the surface accuracy of the molded product can be improved.

[Effects of the Invention] As described above, according to the structure of the press molding die of the present invention, since at least three pins that are brought into contact with the abutting surface with a small area are used, the upper die during pressing is used. The stop position of the relative movement between the member and the lower mold member is always accurately set, so that the thickness accuracy of the molded product can be maintained well and the mold life can be maintained longer.

Further, according to the structure of the press-molding die of the present invention, since the pin is simply inserted into the through hole of the ring member, attachment and removal are easy, and the pin is removed when the pin is repaired. Above.

[Brief description of the drawings]

FIG. 1 (a) is a longitudinal sectional view showing a first embodiment of the structure of the press mold according to the present invention, and FIG. 1 (b) is a partially omitted BB sectional view thereof, and FIG. The figure is a cross-sectional view showing a state when the molding material G is introduced into the mold before pressing in the present embodiment. 2: Lower mold member, 4: Upper mold member, 5: Projection, 6: Sleeve, 7: Opening, 8: Support plate, 10: Holder, 12: Press rod, 20a to 20c: Pin, 22: Butt surface , 24: ring member, 30: transfer arm, 32: suction part, G: molding material.

Claims (4)

(57) [Claims] 1. A press-molding die structure in which an upper die member and a lower die member are slidably disposed in a sleeve in a longitudinal direction of the sleeve, respectively. A means for restricting the movement in the separating direction, and a ring member attached to the upper end surface of the sleeve, the ring member being provided with at least three sleeve longitudinal through holes, A pin of the same length is removably inserted into the hole, and the upper mold member has a butting surface which is brought into contact with the pin for setting the thickness of the molded product. The structure of the press mold. 2. The structure according to claim 1, wherein the through holes are arranged at equal intervals in a circumferential direction of the ring member. 3. The press-molding die according to claim 1, wherein a projection on a central axis in a vertical direction of the sleeve is formed on the upper die member, and a pressing force is applied to the projection from above. Structure. 4. The structure of the press-molding die according to claim 1, wherein both the upper end surface of the sleeve and the abutting surface of the upper die member are in a plane orthogonal to the longitudinal direction of the sleeve.