JPH04176617A - Injection mold - Google Patents

Abstract

PURPOSE:To make it possible to realize shape, due to which the face angle of the flat planes of a molding surface can be finished ultra-precisely by a method wherein the mold concerned consists of a plurality of blocks, which are divided at respective boundary sites and the assembling of which has a circular peripheral surface corresponding to the circular periphery of a recessed part and realizes the mold main body to be fitted to the recessed part and produces a cavity surrounded by polyhedral molding surfaces in the mold main body. CONSTITUTION:A support member 1 is divided by a plane intersecting the center of its recessed part 2 into a left mold 11 and a right mold 12, which are slidable horizontally. When both the left mold 11 and the right mold 12 are registered, the peripheral surface 21 of the recessed part 2 makes itself a continuous circle. When the left mold 11 and the right mold 12 are separated from each other, the peripheral surface 21 is divided into horizontal two parts. Each block 4 has an outer surface made of a circular arcuate surface 41a and an inner surface made of a flat plane 42a. By annularly arranging six blocks 4..., the circular arcuate surfaces 41a of the respective blocks 4 produce a continuous circular peripheral surface 41 and, at the same time, the flat planes 42a of the respective blocks 4 produce a continuous hexagonal molding surfaces 42 and a cavity S, which is formed by being surrounded by said hexagonal molding surfaces 42. Thus, each surface of the molding surfaces forming the cavity can be finished ultra-precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection mold, and particularly to an injection mold suitable for precision molding of optical polyhedrons.

(Prior Art) An injection mold has a cavity portion configured with an uneven surface for filling a material to obtain a molded product. This cavity portion is formed by direct machining on the mold, or is formed by a divided nest (cavity block).

Cavity blocks are usually finished through processes such as wire cutting, electrical discharge machining, and polishing, depending on the required precision.
Incorporated into the injection mold.

Injection molds are classified based on their assembly accuracy: - Boat fishing molds: ±0.03 mm, high precision molds (mechanical parts): ±0
．． 01 body, ultra-high precision mold: Fitted within ±0.002 to 0.005 degrees.

Naturally, the higher the required assembly accuracy, the greater the mold production cost and production time, and the current situation is that ultra-high precision molds ultimately require ultra-precision finishing by hand.

The molds used to manufacture optical components are, of course, ultra-high precision molds (alignment accuracy: ±0.002 to 0°005,
Surface accuracy of approximately 0.0002) is required.

-Ultra high-precision molds for boat fishing are manufactured by carving a recess into the mold body or slide block, usually with a linear surface configuration, using methods such as milling, electrical discharge machining, wire cutting, and polishing lapping to fill the cavity block. be done.

For example, if a hexagonal recess with a thickness of 10 mm is to be dug, the recess is formed using milling, wire cutting, polishing, electric discharge machining, etc., but the shape accuracy depends on the precision of the processing machine used. Machining accuracy.

Furthermore, in order to mechanically finish the final polishing process, it is necessary to index the angles of the mold parts and polish them in sequence. - This step usually results in even greater loss of precision.

(Problems to be Solved by the Invention) One of the design methods employed for forming cavities in conventional general molds, and methods such as electrical discharge machining, wire cutting, and milling described above, do not allow injection molding of optical polyhedrons. There was a problem in that it was not possible to obtain the required flat surface angle for the molding surface of the mold for this purpose.

This invention has been made in view of the above problems, and it is possible to create a polyhedral molding surface that forms a cavity without using digging or cutting, which is the conventional method for forming the cavity surface of a mold. It is an object of the present invention to provide an injection molding die capable of shaping the surface angle of a surface into a shape that can be finished with ultra-precision.

(Means for Solving the Problems) The injection mold of the present invention includes a support member having a recessed portion whose peripheral surface is circular and which requires precision, and a circular recessed portion corresponding to the circular peripheral surface of the recessed portion. and a mold body that is fitted into the recess, and a cavity surrounded by a polyhedral molding surface (straight line, curved surface, aspherical surface) is formed in the mold body. In addition, the mold body is divided into a plurality of blocks at each boundary between adjacent surfaces of the molding surface.

(Function) In this configuration, a plurality of blocks are arranged in an annular shape so that the peripheral surface is circular and the molding surface is polyhedral, and the blocks are fitted into the recessed part of the support member, and the molding material is injected into the cavity surrounded by the molding surface. Then, a polyhedral molded product is injection molded. The molded surface is a continuation of the surfaces individually provided on a plurality of blocks in a polyhedral shape. Since the molded product can be formed using a known processing method that can achieve ultra-precise flatness, each surface of the molded product can be formed with ultra-high precision.

In addition, since the circumferential surface of the recessed part of the support member and the circumferential surface of the mold body are circular, machining is easy.
Furthermore, the positioning accuracy of each block is also improved.

(Example) Next, specific examples of the injection mold of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view of an embodiment of the injection molding die of the present invention configured as a split mold, and FIG. 2 is a sectional view of the injection mold in its usage state.

This mold A includes a support member 1 whose peripheral surface 21 is provided with a circular recess 2, and a mold body 3 divided into six blocks 4 of the same shape.

The support member 1 is divided into a left mold 11 and a right mold 12 along a plane passing through the center of the recessed portion 2, and each is guided by a pair of guides 5.5 and slides left and right as shown by the arrow XSX. I'm starting to get it. When the left mold 11 and the right mold 12 are matched, the circumferential surface 21 of the recessed part 2 (Fig. 2) continues in a circular shape, and when the left mold 11 and the right mold 12 are separated, the circumferential surface 21 moves left and right. It is meant to be divided.

The block 4 has an arcuate surface 41a on the outside and a flat surface 42 on the inside.
By arranging six blocks 4 in an annular shape, the circular peripheral surface 41 of each block 4 has a continuous circular arc surface 41, and the flat surface 42a of each block 4 has a continuous hexagonal shape. A molding surface 42 and a cavity S surrounded by the hexagonal molding surface 42 are formed.

When the mold body 3 formed by the six blocks 4 is fitted into the recess 2 of the support member 1, the arcuate surface 41a of each block 4 is supported from the outside by the circumferential surface 21 of the recess 2. Moreover, the mutual positional relationship of the plurality of blocks 4 is determined by the contact between the end surfaces of the individual blocks 4.

The individual blocks 4 are attached to the support member 1 with mounting bolts 6, and are positioned using positioning pins (not shown). Note that if there is a risk that the blocks 4 will thermally expand and interfere with each other due to the temperature rise during injection molding, a gap should be formed between the blocks 4 and 4 that is sufficient to avoid interference due to thermal expansion. Bye.

The mold body 3 consisting of six blocks 4 is set in the recessed part 2 of the support member 1 as described above, and the mold body 3 is inserted into the cavity S from the nozzle 7 of an injection molding machine (not shown) as shown in FIG.
When molding material is injected into the mold, a hexagonal molded product is formed.

By the way, since the flat surface 42a of the block 4 is a small block, it is easy to finish it with extremely high precision using a known method. For example, the flat surface 42a has a surface roughness of 0.02 g required for each surface of the optical polyhedron.
With mR111ax, the flatness can be finished to 1/8 to 1/10λ or less. Since each surface of the polyhedral molded product is formed by a flat surface 42a, the molded product satisfies the surface roughness and flatness required for a reflective surface of an optical polyhedron.

In the mold A explained above, the molded product is released from the left mold 11.
This is done by sliding the right mold 12 along the guide 5.5 in the direction of separation. Therefore, the mold body 3
It is not necessary to provide a draft angle to the molding surface 42 of the molded product.

3 and 4 show an embodiment in which the mold A is integrated. In this embodiment, since the support member 1 is integral, the draft angle θ of the molded product is formed on the polyhedral molding surface 42 of the mold body 3.

The other configurations, such as the fact that the mold body 3 is divided into six blocks 4 of the same shape, are the same as those explained in FIGS. 1 and 2, so the same parts are given the same reference numerals. The detailed explanation will be omitted.

FIG. 5 shows yet another embodiment. This embodiment differs from the embodiment shown in FIG. 1 in that many types of blocks are used in combination. That is, in this embodiment, six regular hexagonal blocks 4a and six substantially triangular blocks 4a are used.
b and six substantially rectangular blocks 4c. It goes without saying that the mold body 3 formed by arranging these blocks 4a, 4b, and 4c has a circular peripheral surface. In FIG. 5, parts corresponding to those in FIG. 1 are given the same reference numerals and detailed explanations are omitted.

The three embodiments described above are molds A for injection molding a hexagonal optical polyhedron, and FIG. 6 shows a modification of the mold body 3 for injection molding a pentagonal optical polyhedron. An example is shown. The main difference between this mold body 3 and the one shown in FIG. 3 is that the number of blocks 4 is five. Therefore, the same parts are given the same reference numerals and detailed explanation will be omitted.

FIG. 7 shows a mold body 3 formed by combining two arc-shaped blocks 4d, 4d and two substantially fan-shaped blocks 4e, 4e. This mold body 3 is capable of injection molding an optical polyhedron having two arcuate surfaces and two flat surfaces. Other matters are the same as in the case of FIG. 6, and the same parts are given the same reference numerals.

(Effects of the Invention) According to the present invention, each surface of the molding surface forming the cavity can be finished with ultra-precision. As a result, the polyhedron-shaped molded product injection-molded using the precision injection mold of the present invention can fully satisfy the surface roughness and flatness of the flat surface required for the optical polyhedron. Become.

In addition, since the circumferential surface of the recessed part of the support member and the circumferential surface of the mold body are circular, machining is easy.
Furthermore, the positioning accuracy of each block is also improved.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an embodiment of the invention, Fig. 2 is a sectional view of its usage state, Fig. 3 is a plan view of another embodiment, Fig. 4 is a sectional view of Fig. 2, and Fig. 5 is a plan view of yet another embodiment,
FIG. 6 is a plan view of a modified example of the mold body, and FIG. 7 is a plan view of another modified example of the mold body. A... Mold, S... Cavity, l... Support member, 2... Recessed part, 3... Mold body, 4.4a,
4b, 4c, 4d, 4e...Block, 2
1... Peripheral surface of recessed part, 41... Peripheral surface of mold body, 4
2... Molding surface. Patent applicant Fujikoshido Co., Ltd.
Nippon Seikosho Co., Ltd. Koki Engineering Co., Ltd. Taiyo Kosakusho Co., Ltd. Representative Masahiro Nishimori: 'J:2 は(-2 Figure 3 Figure 4 Figure 6 Figure 41a Figure 7 d

Claims (1)

[Claims] 1. A support member having a recessed portion with a circular peripheral surface; and a mold body having a circular peripheral surface corresponding to the circular peripheral surface of the recessed portion and fitted into the recessed portion. , a cavity surrounded by a polyhedral molding surface is formed in the mold body, and the mold body is divided into a plurality of blocks at each boundary between adjacent individual surfaces of the molding surface. An injection mold featuring: