JP2001051197A - Rotary non-axisymmetric prism and metal mold for its injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove projections from a rotary non-axisymmetric prism manufactured by injection molding, and to suppress generation of burrs, and to remove deformation caused by a pattern, by forming mating parts of each adjacent rotary non-axisymmetric face as a ridgeline having a fixed curvature. SOLUTION: A second optical face forming insert die 9 and a third optical face insert die 12 are inserted into a movable side template 102 so that respective mating faces 17, 18 adjoin each other The mating faces (mating parts) 17, 18 have arc shapes (the mating face 17 is a projecting arc and the mating face 18 is a recessed arc) having fixed curvatures, close to a line of intersection 19 between a second optical face forming face 8 and a third optical face forming face 11, from a view of the forming faces 8, 11 from the opening direction (arrow X direction). A step is almost removed between the second optical face forming face 8 and the third optical face forming face 11, to thereby remove a projection between a second optical face 7 and a third optical face 10 which are rotary non-axisymmetric faces of a rotary non-axisymmetric prism 13, a molding product. Also, burrs are not generated and resistance at the mold- releasing time is also removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary non-axisymmetric prism and an injection mold for molding the same by injection.

[0002]

2. Description of the Related Art A rotationally off-axis symmetric prism is disclosed in
As described in Japanese Patent No. 21602, a rotationally asymmetric surface having at least three optical surfaces and having no rotationally symmetric axis (including an amorphous surface, a toric surface, etc., hereinafter) is referred to as a rotational non-axial surface. An optical element having two or more surfaces (referred to as symmetry planes) and whose rotational non-axisymmetric planes are adjacent to each other. The non-axisymmetric rotational prism is often manufactured by injection molding (molding) of plastics for mass production.

[0003]

Generally, when injection molding a prism, a mold is used which incorporates a nest in which a molding surface for forming an optical surface of the prism is divided into several parts. However, when such a mold is used to injection-mold a rotation non-axisymmetric prism having adjacent rotation non-axisymmetric surfaces as described above, the following problem occurs.

The intersection of the rotationally non-axisymmetric surfaces of the rotationally non-axisymmetric prism has a complicated shape. On the other hand, the mutually mating portions of the nests having the forming surface for forming the rotational non-axisymmetric surface are flat. Accordingly, since the shape of the intersection line between the rotationally non-axisymmetric surfaces of the prism and the shape of the nested portion are different, a step (gap) is partially generated at the nested portion. For this reason, when a rotationally non-axisymmetric prism is injection-molded, resin flows into a step (gap) between nests having a forming surface for forming a rotationally non-axisymmetric surface, and a sharp protrusion is formed on the outer periphery of the molded product. It is formed and burrs are likely to occur.

[0005] Further, when the mold is released from the mold, the mold release resistance is concentrated on the portion of the resin which has entered the gap between the nests. Optical characteristics cannot be satisfied.

SUMMARY OF THE INVENTION The present invention has been made in consideration of such a conventional problem. In a mold for injection-molding a rotationally non-axisymmetric prism, a step between the rotationally non-axisymmetric surfaces is reduced. To provide a rotary non-axisymmetric prism which eliminates protrusions in the rotary non-axisymmetric prism produced by injection molding, suppresses the occurrence of burrs, and does not cause deformation due to mold release, and a mold for injection molding therefor. With the goal.

[0007]

To achieve the above object, a rotationally non-axisymmetric prism according to the present invention has at least three optical surfaces, at least two of which have a rotationally symmetric axis. In the non-rotating non-axisymmetric prism that is adjacent to the non-rotating non-axisymmetric surface, the portion where the adjacent non-rotating non-axisymmetric surfaces are joined to each other is characterized by having a ridge line having a constant curvature. I do.

According to the present invention, since the mutually joined portions of the adjacent rotationally non-axisymmetric surfaces are ridges having a constant curvature, no projection is formed on the outer periphery of the formed prism.

According to a second aspect of the present invention, there is provided a mold for injection molding of a rotationally non-axisymmetric prism having at least three optical surfaces, at least two of which have no rotationally symmetric axis. In the injection molding die for a rotationally non-axisymmetric prism that forms an adjacent rotationally non-axisymmetric prism, a part of the mating portion between the adjacent molding surfaces that form the rotationally non-axisymmetric surface has a constant curvature. Characterized by having a ridge line having

According to the present invention, there is no step between the surfaces forming the rotational non-axisymmetric surface of the rotational non-axisymmetric prism.
Therefore, there is no partial protrusion between the surfaces of the rotationally non-axisymmetrical surfaces of the rotationally non-axisymmetrical prism to be formed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments shown in the drawings. In each of the embodiments, the same elements are denoted by the same reference numerals and correspond to each other.

(Embodiment 1) FIGS. 1 to 4 show Embodiment 1 of the present invention. FIG. 1 is a cross-sectional view of a mold when viewed from a direction perpendicular to the opening and closing direction. Only the periphery of the cavity forming the axisymmetric prism is shown. FIG.
FIG. 3 is a perspective view of a nest forming a non-axisymmetric rotational plane;
FIG. 4 is a side view of the nesting from the plane direction forming the rotationally non-axisymmetric surface, and FIG. 4 is a perspective view of the rotationally non-axisymmetric prism of this embodiment.

As shown in FIG. 4, the rotationally non-axisymmetric prism 13 in this embodiment has three optical surfaces 4, 7,.
It has ten. That is, the rotation non-axisymmetric prism 13
Has a first optical surface 4 that is convex and aspheric, and a second optical surface 7 and a third optical surface 10 that are rotationally axisymmetric surfaces. In addition, the second non-axisymmetric rotational plane
The optical surface 7 and the third optical surface 10 are adjacent to each other.

As shown in FIG. 1, a mold for injection-molding the rotationally non-axisymmetric prism 13 includes a movable mold 2 and a fixed mold 3 which are arranged with a parting line (PL) surface as a boundary. It is composed of The fixed-side mold 3 has a fixed-side mold plate 103, and the fixed-side mold plate 103 has a concave and aspheric first optical surface corresponding to the first optical surface 4 of the rotating non-axisymmetric prism 13. A first optical surface forming nest 6 having a surface forming surface 5 is inserted.

The movable mold 2 has a movable mold plate 102 mounted on a movable mounting plate 101. The movable mold plate 102 has a second optical surface forming surface 8 which is a rotationally non-axisymmetric surface corresponding to the second optical surface 7 of the rotationally non-axisymmetric prism 13.
And a third optical surface forming nest 12 having a third optical surface forming surface 11 which is a rotationally non-axisymmetric surface corresponding to the third optical surface 10 of the prism 13 are inserted. Have been.

The second optical surface forming nest 9 and the third optical surface forming nest 12 are inserted into the movable mold plate 102 such that their mating surfaces (matching portions) 17 and 18 are adjacent to each other. As shown in FIGS. 2 and 3, the mating surfaces 17 and 18 are formed on the second optical surface forming surface 8 and the third optical surface when the forming surfaces 8 and 11 are viewed from the mold opening direction (the arrow X direction shown in FIG. 1). It has an arc shape having a constant curvature near the intersection line 19 of the forming surface 11. In this embodiment, the mating surface 17
Is a convex circular arc, the mating surface 18 is a ridge formed by a concave circular arc corresponding to the mating surface 17, and the mating surfaces 17, 18 are in contact with each other without any steps or gaps.

Push pins 14 and 15 are inserted through the movable mold plate 102 to release the rotationally non-axisymmetric prism 13 from the movable mold 2. The tips of the push pins 14 and 15 are in contact with the molded product other than the optical surface. Then, the base end of the push pin 15 and the base end of the push pin 14 are fixed to the push plate 16. A sprue 22 and a runner 23 are formed in the fixed mold plate 103 so as to communicate with a cavity 21 formed by the inserts 6, 9, and 12 when the mold is clamped.

When the rotationally non-axisymmetric prism 13 is injection-molded using such a mold, first, the movable mold 2 is moved in the mold clamping direction (the direction opposite to the arrow X shown in FIG. 1) and fixed. It is brought into contact with the side mold 3. By this contact, the nests 9 and 12 in the movable mold plate 102 and the nest 6 in the fixed mold plate 103 form the cavity 21. Here, the second optical surface forming nest 9 and the third optical surface forming nest 1
The second optical surface forming surface 8 and the third optical forming surface 8 are in contact with each other by an arc having a constant curvature near the intersection line 19 between the second optical surface forming surface 8 and the third optical forming surface 11. There is almost no step or gap between the surface forming surface 11.

Next, molten resin is injected from an injection molding machine (not shown) through a subroutine 22 and a runner 23 into a cavity 21.
Pour into. After the entire cavity 21 is filled with the resin, the resin in the cavity 21 is solidified.
Is formed as shown in FIG. afterwards,
The movable mold 2 is moved in the mold opening direction (the direction of the arrow X shown in FIG. 1). At this time, the rotational non-axisymmetric prism 13
The movable mold 2 moves in the mold opening direction together with the movable mold 2 and the fixed mold 3 moves.
Release from mold. The molded product is released from the movable mold 2 by advancing the push pins 14 and 15. Then, with a take-out device not shown
The rotating non-axisymmetric prism 13 is transported out of the mold 1.

In such an embodiment, the mating surface 17 of the second optical surface forming nest 8 and the third optical surface forming nest 1
The two mating surfaces 18 are in contact with each other at an arc having a constant curvature near the intersection 19 of the second optical surface forming surface 8 and the third optical surface forming surface 11 when viewed from the mold opening / closing direction. The third optical surface forming surface 11 has almost no step. For this reason, there is no protrusion between the second optical surface 7 and the third optical surface 10 which are the rotationally non-axisymmetric surfaces of the rotationally non-axisymmetric prism 13 which is a molded product, and no burrs are generated. In addition, the resistance at the time of release is eliminated.

(Embodiment 2) FIGS. 5 to 7 show Embodiment 2 of the present invention. FIG. 5 is a sectional view of a mold as viewed from a direction perpendicular to the opening and closing direction, and FIG. It is sectional drawing of the nest which forms a non-axisymmetric surface, and is shown from the surface direction which forms a rotational non-axisymmetric surface. FIG. 7 is a perspective view of a rotation non-axisymmetric prism.

In this embodiment, as shown in FIG.
Injection molding is performed on a rotationally non-axisymmetric prism 24 having an optical surface. The rotational non-axisymmetric prism 24 has a concave and aspheric first optical surface 28, and a second optical surface 25 and a third optical surface 31, each of which is a rotational non-axisymmetric surface.
have. Further, the second optical surface 25 and the third optical surface 31
Has an acute angle, and the second optical surface 25 and the third optical surface 31 are adjacent to each other.

The mold 1 includes a movable mold 2 as shown in FIG.
And a fixed mold 3. A second optical surface formation surface having a second optical surface formation surface 26 which is a rotational non-axisymmetric surface corresponding to the second optical surface 25 of the optical non-axisymmetric prism 24 is formed on the fixed mold plate 103 of the fixed mold 3. A nest 27 is inserted. The movable mold plate 102 of the movable mold 2 includes a first optical surface forming nest 30 having a convex and aspherical first optical surface forming surface 29 corresponding to the first optical surface 28 of the prism 24. A third optical surface forming surface 32 that is a rotationally non-axisymmetric surface corresponding to the third optical surface 31 of the prism 24.
An optical surface forming insert 33 is inserted adjacently. In this case, the formation surface 26 of the second optical surface formation insert 27 and the third
The forming surface 32 of the optical surface forming nest 33 is the prism 24
Has an acute angle corresponding to the second optical surface 25 and the third optical surface 31.

The second optical surface forming nest 27 and the third optical surface forming nest 33 are respectively mating surfaces (matching portions).
34 and 35 are adjacent on the parting line (PL) plane. The mating surfaces 34 and 35 are formed so that the forming surfaces 26 and 32 are perpendicular to the mold opening direction (the direction of the arrow Y shown in FIG. 5).
6, as shown in FIG. 6, the second optical surface forming surface 2
It has an arc shape having a constant curvature near the intersection line 37 between the sixth optical surface forming surface 32 and the third optical surface forming surface 32. Specifically, as shown in FIG. 6, the mating surface 34 is a convex arc and the mating surface 3
5 is a ridge formed of a concave arc corresponding to the mating surface 34, and the mating surfaces 34 and 35 are in contact with each other without any step or gap.

When the rotationally non-axisymmetric prism 24 is injection-molded using such a mold, first, the movable mold 2 is moved in the mold clamping direction (the direction opposite to the arrow X shown in FIG. 5) and fixed. It is brought into contact with the side mold 3. By this contact, the cavity 36 is formed by the nests 30 and 33 in the movable mold plate 102 and the nest 27 in the fixed mold plate 103. At this time, the second optical surface forming nest 27 and the third optical surface forming nest 33 are mutually connected by an arc having a constant curvature close to the intersection 37 between the second optical surface forming surface 26 and the third optical surface forming surface 32. , The second optical surface forming surface 26 and the third
There is almost no step or gap between the optical surface forming surface 32.

Next, molten resin is injected from an injection molding machine (not shown) through the sprue 22 and the runner 23 into the cavity 36.
Pour into. After the entire cavity 36 is filled with the resin, the resin in the cavity 36 is solidified to obtain the rotational non-axisymmetric prism 24 shown in FIG.

Thereafter, the movable mold 2 is opened in the mold opening direction (FIG. 5).
In the direction of arrow X shown in FIG. At this time, the rotationally non-axisymmetric prism 24 moves in the mold opening direction together with the movable mold 2 and separates from the fixed mold 3. The molded product is released from the movable mold 2 by advancing the push pins 14 and 15. Thereafter, the rotating non-axisymmetric prism 24 is transported out of the mold 1 by a take-out device or the like (not shown).

When the second optical surface 25 and the third optical surface 31, which are rotationally non-axisymmetric surfaces, have an acute angle, in the molding according to the first embodiment, there is a possibility that the mold release resistance increases and deformation occurs. However, in this embodiment, the second optical surface forming surface 26 and the third optical surface forming surface 32 forming the rotational non-axisymmetric surface are separated from each other by opening the mold, so that a portion where the mold release resistance is increased does not occur. Therefore, no deformation occurs.

From the above description, the present invention includes the technical ideas described in the following additional items.

(Supplementary Item 1) A rotationally non-axially symmetric surface having at least three optical surfaces, two or more rotationally non-axially symmetric surfaces among the optical surfaces, and the rotationally non-axially symmetric surfaces being adjacent to each other. A non-rotationally non-axially symmetric prism, wherein a portion where the surfaces of the adjacent non-rotationally non-axially symmetric surfaces meet each other is a ridge having a constant radius of curvature.

According to the present invention, since the mutually joined portions of the adjacent rotationally non-axisymmetric surfaces are ridges having a constant curvature, no projection is formed on the outer periphery of the prism to be formed.

(Supplementary Item 2) A rotationally non-axially symmetric surface having at least three optical surfaces, two or more rotationally non-axially symmetric surfaces among the optical surfaces, and the rotationally non-axially symmetric surfaces being adjacent to each other. In the injection molding die for a prism, there is provided a ridge line having a constant radius of curvature at a joint portion between the rotational axis symmetry surfaces on the mold nest side forming the rotational non-axisymmetric surface. Mold for molding.

In the present invention, since there is no step between the molding surface of the mold nest forming the rotationally non-axisymmetric surface of the rotationally non-axisymmetric prism and the molding surface, the rotational non-axially symmetric prism to be molded is not rotated. No partial protrusion occurs between the surfaces of the axisymmetric surfaces.

[0034]

According to the first aspect of the present invention, since the mutually joined portions of the adjacent rotationally non-axisymmetric surfaces are ridges having a constant curvature, a projection is formed on the outer periphery of the formed prism. No burr is formed and no burr is generated.

According to the second aspect of the present invention, since there is no step between the surfaces forming the rotationally non-axisymmetric surface of the rotationally non-axisymmetric prism, the rotationally non-axially symmetrical prism formed by the rotationally non-axisymmetric prism is formed. There is no partial projection between the surfaces, no resistance to release, and no deformation due to release.

[Brief description of the drawings]

FIG. 1 is a partially broken side view of a mold according to a first embodiment.

FIG. 2 is a perspective view of a nest according to the first embodiment.

FIG. 3 is a side view of the nest of the first embodiment.

FIG. 4 is a perspective view of the rotation non-axisymmetric prism according to the first embodiment.

FIG. 5 is a partially broken side view of a mold according to a second embodiment.

FIG. 6 is a side view of a nest according to the second embodiment.

FIG. 7 is a perspective view of a rotationally non-axisymmetric prism according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 6 9 12 Nesting 8 11 15 Optical surface molding surface 13 Rotational non-axisymmetric prism 17 18 Mating surface

Claims (2)

[Claims] 1. A rotationally non-axially symmetric prism having at least three optical surfaces, at least two of which are adjacent to each other as a rotationally non-axially symmetric surface having no rotationally symmetric axis, Of the rotating non-axisymmetric planes
A rotating non-axisymmetric prism having a ridge line having a constant curvature. 2. A rotationally non-axisymmetric prism forming a rotationally non-axisymmetric prism having at least three optical surfaces, at least two of which are adjacent to a rotationally non-axisymmetric surface having no rotationally symmetric axis. In a mold for injection molding of a prism, a rotationally non-axisymmetric prism characterized in that a joining portion between molding surfaces for molding the adjacent rotationally non-axisymmetric surfaces is a ridge line having a constant curvature. Mold for injection molding.