JP2990254B2 - Light-weight vacuum cast product and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a small lot of a resin molded product which is used for a tail blade which is a tail rotor of an unmanned helicopter and which requires weight reduction, such as the tail blade.

[0002]

2. Description of the Related Art An injection mold (silicon rubber mold) made of silicon rubber is manufactured by a vacuum casting method using a master model.
Resin molding (vacuum casting) using vacuum casting method
When the master model 1 is produced, a master model 1 is fixed in a frame 2 as shown schematically in FIG. Silicon rubber 3
To fill the master model 1 and put the frame 2 in a vacuum chamber 4 to defoam the silicone rubber 3, and then put the frame 2 together with the silicone rubber 3 and the master model 1 in, for example, an oven and heat the silicone rubber 3. 3 is cured, the cured silicone rubber 3 is cut with a scalpel, and the master model 1 is taken out to obtain a silicone rubber mold 5 serving as a matrix.

The silicon rubber mold 5 manufactured as described above
Is arranged in a vacuum chamber 6, and a main agent 7a and a curing agent 7 of a thermosetting resin 7 such as a urethane resin or an epoxy resin.
b is placed in a vacuum chamber 6, the inside of the vacuum chamber 6 is evacuated to a reduced pressure, the main agent 7 a and the curing agent 7 b are preliminarily defoamed, mixed and stirred, and the thermosetting resin 7 is converted into a silicone rubber mold 5. Inject,
Then, the thermosetting resin 7 is spread over the entire silicone rubber mold 5 by introducing air into the vacuum chamber 6 and returning the inside of the vacuum chamber to atmospheric pressure. For example, it is placed in an oven and heated to cure the thermosetting resin 7, the silicon rubber mold 5 is broken, and a resin molded product (vacuum cast product) 8 is taken out.

[0004] A resin molded product 8 produced by the method described above.
Is a solid product of the thermosetting resin 7 ', the weight of which is determined by the specific gravity of the thermosetting resin 7', and there is a limit in reducing the weight.

[0005]

As described above, in the conventional vacuum casting method, the specific gravity of the thermosetting resin 7 'is multiplied by the volume of the resin molded product (vacuum cast product) 8 rather than the weight. Lightweight vacuum castings could not be made. The purpose of this invention is
An object of the present invention is to provide a lightweight vacuum cast product which cannot be obtained by the conventional vacuum casting method, and a method of manufacturing the same.

[0006]

[Means for Solving the Problems]

(1) A method for manufacturing a lightweight vacuum cast product according to claim 1 includes a step of producing a primary injection mold made of silicon rubber by a vacuum injection method using a primary master model, and using the primary injection mold. , A step of manufacturing a thermosetting resin vacuum cast product (resin molded product) by a vacuum casting method, and thinning the outer peripheral surface of the vacuum cast product (excluding small portions at a plurality of dispersed positions). Shaving to create a secondary master model, part 2
Using a next master model, a step of preparing a secondary injection mold made of silicon rubber by a vacuum casting method, injecting a foaming material into the secondary injection mold, curing, and removing the mold to prepare a foamed core material. A step of fitting the foamed core material to the primary injection mold and clamping the mold; and wrapping the foamed core material with a thermosetting resin by the vacuum casting method using the primary injection mold. And producing a light-weight vacuum cast product in a state. (2) The invention according to claim 2 is a lightweight vacuum cast product manufactured by the manufacturing method according to the above (1).

[0007]

An embodiment of the present invention will be described in the order of steps with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 2 are denoted by the same reference numerals. (A) As shown in FIG. 1A, using a primary master model 1, a primary injection mold 5 made of silicon rubber is manufactured by the vacuum casting method described in the conventional example. In this example, the primary injection mold 5
Is divided into an upper mold 5a and a lower mold 5b when the master model 1 is taken out by cutting the silicone rubber with a scalpel. (B) The primary injection molds 5 (5a, 5b) are combined and fixed with, for example, a tape (referred to as mold clamping), and are used to form a thermosetting resin as shown in FIG. A vacuum cast product (resin molded product) 8 is produced. (C) As shown in FIG. 1C, the outer peripheral surface of the vacuum cast product 8 (excluding small portions at a plurality of dispersed positions) is 0.5 to 2 mm.
By shaving, a secondary master model 9 is produced. The portion that has been removed without being scraped becomes the positioning projection 9a. (D) Using a secondary master model 9, a secondary injection mold 10 made of silicon rubber as shown in FIG.
(10a, 10b) are manufactured. (E) The secondary injection mold 10 (10a, 10b) is clamped,
A two-component foam material is injected, cured, and demolded to produce a foam core material 11 as shown in FIG. 1E. Foam core material 11 is 2
It has substantially the same shape as the next master model 9, and has a positioning projection 9a formed integrally therewith. In this step, since the foam material is molded, the vacuum casting method is not used. (F) Fit the foam core 11 into the primary injection mold 5. That is, the foamed core material 11 is positioned and arranged in the primary injection mold 5 (5a, 5b) using the positioning protrusion 11a (FIG. 1F), and the mold is clamped. (G) Using the primary injection mold 5 (5a, 5b), a thermosetting resin is injected into the gap between the foamed core material 11 and the inner peripheral surface of the primary injection mold 5 by a vacuum casting method, and cured. The mold is removed to produce a lightweight vacuum cast product 12 as shown in FIG. 1G. The lightweight vacuum cast product 12 has a built-in foam core material 11, and the protruding surfaces of the positioning projections 11a appear as they are at a plurality of locations on the external surface.

[0008]

As described above, the vacuum cast product 12 made according to the present invention is capable of wrapping the core material 11 made of a foam material inside the skin of the thermosetting resin. It can be a molded product.

[Brief description of the drawings]

FIG. 1 is a principle diagram for explaining an embodiment of the present invention in the order of manufacturing steps.

FIG. 2 is a diagram showing a basic manufacturing process of a conventional vacuum cast product.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B29C 69/02 B29C 69/02 B29K 101: 10 105: 04 (72) Inventor Yoshihiko Watanabe 1-21 Dogenzaka, Dogenzaka, Shibuya-ku, Tokyo Ban No. 6 Date this aviation electronics industry within Co., Ltd. (56) reference Patent Sho 60-244510 (JP, a) JitsuHiraku flat 3-20122 (JP, U) (58 ) investigated the field (Int.Cl. ⁶ B29C 39/02-39/12 B29C 39/22-39/42 B29C 33/38-33/40

Claims (2)

(57) [Claims] 1. A step of manufacturing a primary injection mold made of silicon rubber by a vacuum casting method using a primary master model, and a step of forming a thermosetting resin by a vacuum injection method using the primary injection mold. A step of manufacturing a vacuum cast product (resin molded product); a step of forming a secondary master model by shaving the outer peripheral surface of the vacuum cast product (excluding small portions at a plurality of dispersed positions). Using the secondary master model to form a secondary injection mold made of silicon rubber by vacuum casting, injecting a foaming material into the secondary injection mold, curing, removing the mold, and removing the foam core material A step of fitting the foamed core material into the primary injection mold and clamping the mold; and using the primary injection mold to vacuum-cast the foamed core material into a thermosetting resin. Manufacturing a lightweight vacuum cast product wrapped in The manufacturing method for lightweight vacuum cast products. 2. Using a primary master model, a primary injection mold made of silicone rubber is manufactured by a vacuum injection method, and a vacuum injection method made of a thermosetting resin is manufactured by a vacuum injection method using the primary injection mold. A mold product is manufactured, and a secondary master model is manufactured by thinly shaving the outer peripheral surface of the vacuum cast product (excluding the small portions at the plurality of dispersed positions), and a vacuum injection is performed using the secondary master model. A secondary injection mold made of silicone rubber is manufactured by a molding method, a foaming material is injected into the secondary injection mold, cured, and demolded to form a foamed core material. The foamed core material is formed in the primary injection mold. A light-weight vacuum-cast product manufactured by vacuum casting using the primary injection mold, fitted with a mold, and wrapping the foamed core material with a thermosetting resin.