JP2000205192A - Resin-made casing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mass productivity and reduce the cost by constituting a resin-made casing having an opening from an inner casing consisting of the combination of a plurality of preliminarily resin-molded split inner casings and an outer casing for covering at least the outer surface thereof. SOLUTION: This pump casing 10 in a double volute pump is formed of a resin-made inner casing 16 including a volute 14 having two passages 14a, 14b with a bulkhead 12 in between, and a resin-made outer casing 18 for covering the outside of the inner casing 16 so as to enclose it. The outer casing 18 has a suction port on one axial end surface 20, and the tip end surface 24 of the volute 14 has a discharge port. The inner casing 16 is formed of split inner casings 16a, 16b divided into two, and the outer casing 18 is resin-molded so as to cover the outer surface of the inner casing 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a complicatedly shaped resin casing having an undercut portion and a bag-like portion.

[0002]

2. Description of the Related Art A reaction injection molding method is a method in which two or more kinds of low-molecular-weight and low-viscosity liquid raw materials are introduced into a mixing chamber under pressure, mixed, and simultaneously injected into a closed mold. It is. Conventionally, a relatively large pump casing or the like made of metal can be made of resin by, for example, a reaction injection molding method (Reaction Injection Molding) using a resin containing dicyclopentadiene (DCPD) as a main raw material. This makes it possible to utilize the features of a resin that is lightweight and has excellent corrosion resistance and vibration resistance.

[0003] Among such resin casings, those having a complicated shape such as an undercut portion or a bag-like portion cannot be molded by an integral molding die, and are widely used in casting technology and vacuum casting technology. It has been manufactured by molding using a sand core or a fugitive core silicon rubber mold, and removing the core after molding.

[0004]

However, when a core is used, the productivity is limited by the core manufacturing and removal capabilities, and the resin material is injected into the mold controlled at a certain temperature in a given cycle to be applied. Not only can the full advantage of resin molding that it can be mass-produced by shaping not only be exhibited, but also the quality level of the molded product surface is governed by the finished state of the core. In particular, when a sand mold is used for a large core, production of a sand mold core, surface treatment such as coating,
Labor-intensive man-hours are required for operations such as mold dispersion, sand removal, and finishing after molding, and manufacturing costs could not be reduced.

It is also conceivable to cast a resin half-split member without using a core and join the half-split members together by a flange or the like, but the joining surface is exposed to the outside. Therefore, it is necessary to secure the sealing property,
Other advantages of resin molding, such as avoiding such a seal portion by integrally molding the whole, cannot be exhibited.

[0006] In view of the above problems, the present invention provides a resin casing which makes full use of the features of resin molding, is rich in mass productivity, has high sealing properties, and can be manufactured at low cost. Aim.

[0007]

The invention according to claim 1 is a resin casing having an opening, wherein the inner casing is formed by combining a plurality of divided inner casings formed in advance with resin. An outer casing formed by resin molding so as to cover at least an outer surface of the inner casing.

Thus, the split inter-casing is formed in an open shape without using a core, and the outer casing is integrally formed by casting the inner casing formed by combining the divided inter-casings. Can be manufactured without exposing the resin to the outside.

According to a second aspect of the present invention, there is provided the resin casing according to the first aspect, wherein a reinforcing member is embedded in the outer casing so as to connect the plurality of divided inner casings. . As the reinforcing material, a metal such as light weight and high strength is preferable.
It is preferable that the split inner casing be sandwiched as a letter-shaped plate. Thereby, the swelling deformation due to the internal pressure of the divided inner casing can be prevented. By arranging such a reinforcing member in the reinforcing rib of the outer casing, its size can be ensured.

The invention according to claim 3 is the resin casing according to claim 1 or 2, wherein a labyrinth structure is provided on a joint surface between the outer casing and the inner casing. Thereby, it is possible to improve the sealing property at the resin joint surface between the inner casing and the outer casing.

According to a fourth aspect of the present invention, the divided inner casings are fastened to each other by a fastener via a partition formed inside the inner casing. A resin-made casing described in the above. Thus, the divided inner casings can be firmly connected to each other using the partition wall.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention applied to a so-called double volute pump casing.
The pump casing (resin casing) 10 includes a resin inner casing 16 in which a volute 14 having two flow paths 14a and 14b with a partition wall 12 interposed therebetween is formed. Outside the inner casing 16,
And an outer casing 18 made of resin which covers so as to enclose the casing.

The outer casing 18 is provided with a suction port 22 at one end face 20 in the axial direction for sucking a liquid from outside, and a discharge port 26 for discharging the internally pressurized liquid to the outside at a tip face 24 of the volute 14. Is provided. The other end surface 28 in the axial direction is formed with a mounting port 30 for mounting a drive unit. On the end surfaces 20, 24, 28 of the outer casing 18, a concave groove 32 for mounting an O-ring and a bolt hole 34 surrounding the suction port 22 and the discharge port 26 are formed.

In this example, the inner casing 16 is D
It is formed by a reaction injection molding method using a resin material mainly composed of CPD, and is constituted by divided inner casings 16a and 16b divided into two by a dividing surface shown in FIG. Each of these divided inner casings 16
Each of a and 16b has an open shape, does not have an inner undercut portion or a bag-like portion, and can be formed without using a core.

As described above, the divided inner casing 16
By molding a and 16b without using a core, the fluid passage surfaces of these inner peripheral surfaces can be formed on a flat surface free from defects. Therefore, the finishing step by manual work can be omitted or simplified, and a smooth surface finish can be obtained, so that the pump efficiency can be improved. Further, it is possible to improve the circumference of the liquid raw material and eliminate the occurrence of defects due to voids.

The outer casing 18 has two divided inner casings 16a and 16b assembled together in a molding die with their joining surfaces (cut surfaces S) aligned, and supplies a resin material thereto to form the divided inner casings 16a and 16b. A so-called “cast-in” method of bringing the material into close contact and curing is used. Normally, the same material as that used to form the divided inner casings 16a and 16b is used and molded by the same reaction injection molding method, but another material or molding method may be used. The thickness of the inner casing 16 is set so as not to be damaged or deformed during the molding. On the other hand, the thickness of the outer casing 18 is set to a thickness having sufficient rigidity as the pump casing 10.

The inner casing 16 includes divided inner casings 16a and 16b and an outer casing 18
The joint surface (resin joint surface) of the divided inner casing 16
a labyrinth structure 36 for improving the sealing performance of these parts near the parting surface S between the a and 16b and the part connected to the end faces 20, 24 and 28 of the outer casing 18.
a, 36b and 36c are provided. The first labyrinth structure 36a is connected to the suction port 22 of the inner casing 16.
The side end 22a is provided as an annular protrusion 38a extending along the outer periphery thereof. Second labyrinth structure 3
6b is provided on the end 26a of the inner casing 16 on the side of the discharge port 26 as an annular convex portion 38b extending along the outer periphery, and a lip 40a is provided on the outer periphery. The third labyrinth structure 36c is provided near the split surface S between the divided inner casings 16a and 16b as an annular lip 40b extending along the outer periphery thereof.

Inside the outer casing 18, metal reinforcing members 40a, 40b, 40c, which are U-shaped flat plates surrounding the outer edge of the inner casing 16, are embedded so as to sandwich the outer edge. This reinforcing material 40a,
Are arranged in the outer surface of the outer casing 18 corresponding to a plurality of plate-like reinforcing ribs 42a, 42b, 42c,... Which extend radially at intervals in the circumferential direction. The reinforcing members 40a, 40b, 40c ...
It is necessary to be lightweight and have a predetermined strength, and in this embodiment, it is made of metal, but the material and shape can be appropriately selected.

FIG. 4 illustrates the structure of a molding mold for injection-molding the outer casing 18. As shown in FIG.
Here, cores 50a, 50b, which form details, are provided in two molds 48a, 48b each having an inner cavity 44a, 44b and an inlet 46a, 46b communicating therewith.
50b and divided inner casings 16a and 16b formed in advance by resin molding are supported. The split inner casings 16a and 16b are provided with the suction port 22, the discharge port 26, and the end 30 of the mounting port 30 for convenience of operation.
extensions 52a, 52b, 52c acting as cores on
Are formed respectively. A support block for suppressing the deformation may be provided inside the inner casing 16.

Such a molding mold is provided with the cores 50a, 50b and the divided inner casings 16a, 16b in the cavities 44a, 44b of one of the molds 48a, 48b.
After assembly of b, the cavity is covered with the other mold. In the thus-formed molding mold, a reaction injection molding or the like is performed by injecting a resin from the injection ports 46a, 46b, and after the resin is solidified, the mold 48a,
Open 48b and remove the core and support block. Then, the extended portions of the divided inner casings 16a and 16b are removed by cutting or the like, and finishing is performed as necessary,
A pump casing as shown in FIGS. 1 and 2 is obtained.

As described above, the divided inner casing 16
By subjecting the outer casing 18 to injection molding using the cores a and 16b as a core, the resin casing 10 in which the split surface S is not exposed to the outer surface can be manufactured. In this example,
Since the outer casing 18 covers the suction port 22, the discharge port 26, and the mounting port 30, the split surface S is not exposed to the end faces 20, 24, 28 that are the mounting surfaces of the external pipes and the drive unit. Inner casing 16 and outer casing 1
8 (the resin joint surface) does not necessarily have sufficient adhesion, but the split surface S communicating therewith is not exposed to the outer surface or the joint surface, which may cause a problem in the sealing property. There is no.

The divided inner casings 16a, 16
The partitioning walls 12 of 6b may be fastened from outside the inner casing 16 with fasteners such as bolts so that the divided inner casings 16a and 16b are firmly integrated. Further, in each embodiment, an example is shown in which the divided inner casings 16a, 16b and the outer casing 18 are molded by reaction injection molding. However, for example, the divided inner casing may be molded by blow molding. Of course.

[0023]

As described above, according to the present invention,
A resin casing such as a pump casing can be molded without using a core, which makes it possible to produce high-quality and complex-shaped products at low cost, taking advantage of the greatest advantage of resin molding. it can.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a double volute pump casing according to an embodiment of the present invention.

FIG. 2A is a cross-sectional view taken along the line AA of FIG. 1;
FIG. 2B is an enlarged view of a portion A in FIG.

FIG. 3A is a cross-sectional view taken along line BB of FIG. 1;
1B is a cross-sectional view taken along the line CC of FIG. 1, and FIG.
FIG. 4 is a cross-sectional view taken along line DD of FIG.

FIG. 4 is a cross-sectional view showing a configuration of a mold for molding the double volute pump casing of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Resin casing 16 Inner casing 16a, 16b Split inner casing 18 Outer casing 22 Suction port 26 Discharge port 30 Mounting port 36a, 36b, 36c Labyrinth structure 40a, 40b, 40c Reinforcement material 48a, 48b Mold

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akihisa Machida 11-1 Haneda Asahimachi, Ota-ku, Tokyo F-term in EBARA CORPORATION (reference) 3H034 BB01 BB06 CC03 DD08 DD22 DD24 EE12 4F206 AA46 AD03 AH05 AM03 JA01 JB12 JB20 JQ81 JW21

Claims (4)

[Claims] 1. A resin casing having an opening, comprising: an inner casing formed by combining a plurality of divided inner casings formed in advance of a resin; and a resin molded so as to cover at least an outer surface of the inner casing. A resin casing, comprising: an outer casing. 2. The resin casing according to claim 1, wherein a reinforcing material is embedded inside the outer casing so as to connect the plurality of divided inner casings. 3. The resin casing according to claim 1, wherein a labyrinth structure is provided on a joint surface between the outer casing and the inner casing. 4. The divided inner casings are
The resin casing according to any one of claims 1 to 3, wherein the casing is fastened with a fastener via a partition wall formed inside the inner casing.