JPH0276711A - Method for molding impeller of centrifugal hydraulic machinery and mold used therefor - Google Patents

Abstract

PURPOSE:To stabilize the quality of an impeller and make it possible to perform the inspection of molded item by sampling and consequently to reduce the inspection man-hours by a method wherein molten resin passed through a sprue and gates is made to simultaneously start to flow from the mouthring and boss part of an impeller so as to well-balancedly and equally fill the cavities for a main plate and for a side plate. CONSTITUTION:When the injection molding of a resin impeller 6 is intended, after a top and a bottom forces 5 and 4 are clamped together, molten resin is injected from an inlet 7 into the forces so as to flow the molten resin through a sprue 8 and runners 21 out of respective pin gates 22 and 23, which are provided in the same number as the number of vanes, into the boss part 17 of the impeller and the mouthring 15a part of a side plate 15 simultaneously in order to be equally filled in the cavities 4a and 4b, which correspond to a main plate 16 and to the side plate 15 respectively. Thus, no excessive force, which deforms a core formed piece 1, is applied, resulting in realizing well-balanced molding and allowing to obtain the molded item 6 of a centrifugal impeller with the thickness of specified dimensions.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for integrally molding a resin by injection molding using an alloy that can be eluted and removed, such as a low melting point metal, as a core. The present invention relates to a method for integrally molding an impeller for a centrifugal fluid machine (hereinafter simply referred to as a centrifugal impeller) and a mold used in the method.

[Conventional technology]

Conventionally, when designing a mold for resin molding a centrifugal impeller using a core made of a low melting point alloy, there were five stages as shown in Figure 3.
A baseboard part (core holding part) 2 of 5K is integrally formed to protrude the center part of a core molded product 1 having a shape corresponding to the internal fluid passage (space) part of an impeller. A positioning ring 3 is embedded integrally with the baseboard portion 2 to ensure a tight fit between the baseboard portion 2 and the mold.

The positioning ring 3 of the core molded product 1 is tightly fitted into a gap (recess) 4aK corresponding to the baseboard of the lower mold 4, and the inner surface of the lower mold 4 has an impeller side plate. (shroud) 15 is also formed in the upper mold 5.
A void 5a corresponding to the impeller main plate 16 is formed on the inner surface of each of the impeller main plates 16.

When injection molding a resin impeller (product) 6, after clamping the upper and lower molds 5.4 as shown in the figure, when molten resin is injected into the mold from the injection lower, the sprue 8 and runner f
- 9, the molten resin enters the gap SaK on the main plate side of the impeller, then passes through the gap 1a in the part corresponding to the blade of the core 1, and flows into the gap 4bK in the part corresponding to the side plate 15, as shown by the arrow. Filling is completed: At this time, the baseboard part 2 of the core 1 is tightly fitted and supported by the inner surface of the cavity 4a of the lower mold 4, and the peripheral part 1b is sandwiched by the opposing surfaces of both upper and lower molds 5.40. and is supported.

[Problem to be solved by the invention]

As mentioned above, the core molding machine set in the mold 4.5 is moved from the discharge side 11 of the impeller to the suction side 13 as shown in FIG. 2a. ) is strong, and because the space between adjacent blades 14 is narrow, pressure is first applied from the main plate 16 (Fig. 3) side, which is filled with resin.
Easy to deform.

Furthermore, the temperature of the core molded product 1 rises due to the influence of the resin temperature, which causes the core molded product 1 to deform itself, resulting in the main plate of the manufactured impeller 6, as shown in FIG. 4(a). 6 is thick, side plate 1
5 will result in a thin molded product.

Furthermore, the gap in the main plate is mainly filled with resin and the side plate comes later, so in the event of a short circuit, the side plate will be insufficiently filled.

As a result, variations occur in the thickness dimensions of the main plate 16 and the side plates 15, and if they do not fall within the specified allowable limit dimensions,
(Trouble) has occurred.

In addition, since there is a large variation in dimensions, there is a problem in that a lot of time and effort is required for molding conditions and all inspections of the molded product.

The present invention solves the above problems, stabilizes the quality of the impeller, which is a molded product, reduces inspection man-hours by making molded product inspection into a sampling inspection, and improves the quality of the molded product. The object of the present invention is to provide a method and a mold for use in the method.

[Means to solve the problem]

In order to achieve the above object, the resin molding method of the present invention involves setting a core molded product having a shape corresponding to the internal fluid passage of an impeller in a mold of an injection molding machine, and after clamping the mold.
In an impeller forming method for a centrifugal fluid machine in which molten resin is injection molded into the mold, the molten resin that has passed through the sprue and gate begins to flow simultaneously from the mouth ring and boss of the impeller, filling the gap between the main plate and the side plate. It is characterized by filling the parts evenly and in a well-balanced manner.

It is characterized in that the molten resin begins to flow from the mouth ring and the boss at the same time through the same number of pins as the number of impeller blades provided on the mouth ring and the boss, respectively.

The mold of the injection molding machine used for the above molding method is
It is characterized by having the same number of pin gates as the number of impeller blades on the mouth ring and boss part of the impeller.

[Effect]

Since the present invention is constructed as described in 5 above, when injection molding a resin impeller, the core and When injected, the molten resin passes through a sprue (injection path) and a launch corresponding to the distribution path, and simultaneously flows out from pin gates with the same number of blades to the boss part and mouth ring part, and fills the gap corresponding to the main plate and side plate. The area is evenly filled with the resin.

As a result, an unreasonable force that deforms the core molded product is not applied, resulting in well-balanced molding, and a centrifugal impeller molded product having a prescribed thickness dimension can be obtained.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a mold die of an injection molding machine for molding a centrifugal impeller made of resin, and in the figure,
The same reference numerals as those shown in FIG. 3 indicate the same or similar items.

In the figure, the core molded product 1 has a shape corresponding to the internal fluid passage (gap) trap of a centrifugal impeller, and is formed to protrude forward (to the left in the figure), as also shown in FIG. A positioning ring 3 made of ordinary steel, special steel, particularly stainless steel, or aluminum alloy is integrally embedded in the baseboard portion (core valve) 2.

As shown in FIG. 1, the positioning ring 3 of the core molded product 1 has a gap (recess) 5a corresponding to the baseboard of the upper mold 50.
K is tightly fitted, and the inner surface of the upper mold 5 has a gap 5b corresponding to the impeller side plate 15.
However, on the inner surface of the lower mold 4, gaps 4a corresponding to the impeller main plate 16 are formed.

The upper surface of the upper mold 5 is provided with a sprue 8 communicating with the molten resin injection lower and a runner 21 connected to the sprue 8. Inject the same number of pins as the number of blades? −
1 (in injection molding, the diameter or maximum dimension provided where material flows from the sprue into the cavity -0.76+w
Refers to the following orifice. ) 22 and pin gates 23 of the same number as the number of blades (wings) for injecting molten resin into the mouth ring 15a at the inlet of the side plate 15 are connected to each other. In the figure, 18 is an extrusion pin for taking out the core molded product 1 from the resin solidification firefly.

When injection molding a resin impeller (product) 6, after clamping the upper and lower molds 5.4 as shown in the figure, when molten resin is injected into the mold from the injection lower, the sprue 8, runner 21
After that, each pin arranged in the same number as the number of blades -) 22.2
3, the impeller boss portion 17 and the mouth ring 1 of the side plate 15
At the same time, the molten resin flows out to part 5a, and the voids 4a and 5b corresponding to the main plate 16 and side plate 15 are evenly filled with the K resin.

Note that the impeller boss portion 17 and the mouth ring 15 of the side plate 15
When flowing to part a at the same time, the relationship between the volume difference between the main plate 16 and the side plate 15 and the injection pressure ensures that the main plate 16 and the side plate is #! in a well-balanced manner. C.Boss part and mouth ring for injection and filling? -) It goes without saying that the dimensions must be adjusted.

This prevents the application of excessive force that would deform the core molded product 1, resulting in well-balanced molding, resulting in a centrifugal impeller molded product 6 having the specified thickness as shown in Figure 4 (■). Obtainable.

The core 1 is made of a low-melting point metal, for example, a substance mainly consisting of lead and tin, and the resin injected from the injection lower is usually ? Liamide, polypropylene, ABS (
Acrylonitrile/tutadiene black ethylene resin), polyethylene, precarbonate, etc. are often used.

After being molded at 5Kt as described above, the core 1 is heated to a predetermined temperature (above the melting point of a material that can be eluted and removed, such as a low melting point metal).
(temperature below the thermal deformation temperature of the impeller resin) is heated, melted and removed.

Note that the present invention can be implemented using a mold other than a mold using a positioning ring as in this embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, the molten resin injected into the mold starts flowing from the mouth ring and the boss at the same time. The gaps between the main plate and side plates are filled evenly and in a well-balanced manner. Furthermore, by providing pin gates at multiple points and in the same number of spaces between the blades, distortion and deformation can be reduced when manufacturing molded products that are easily deformed.
It will flow in a well-balanced manner around the entire circumference. This cancels out the forces that deform the core and prevents undue force from being applied from both sides of the core, making it possible to produce a centrifugal impeller molded product with a specified thickness.

Therefore, it is possible to stabilize the quality of the centrifugal impeller, which is a molded product, to reduce the number of inspection steps by conducting sampling inspections for molded product inspection, and to improve the quality of the centrifugal impeller.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of a mold used for molding the resin centrifugal impeller of the present invention, Fig. 2 (ω and (b) are a plan view and a sectional view of a core molded product, Fig. 3 is a cross-sectional view of a molding die showing a conventional example, Fig. 4 (b) is a cross-sectional view of a centrifugal impeller molded by the conventional method, and Fig. 4(b) is a cross-sectional view of a centrifugal impeller molded by the method of the present invention. It is a sectional view of a car. 1... Core molded product, 3... Positioning ring, 4
．． 5... Mold, 6... Centrifugal impeller (product), 8...
... Sprue, 15... Side plate, 15a...
Liner ring, 16...Main plate 1.21...Runner, 22.23...Pin gate. Figure 4

Claims (1)

[Claims] 1. A core molded product having a shape corresponding to the internal fluid passage of an impeller is set in a mold of an injection molding machine, and after the mold is clamped, molten resin is injected into the mold. In a method for forming an impeller of a centrifugal fluid machine, the molten resin that has passed through the sprue and gate begins to flow simultaneously from the mouth ring and boss of the impeller, filling the gap between the main plate and side plate evenly and in a well-balanced manner. A method for forming an impeller for a centrifugal fluid machine, characterized by: 2. Install the same number of pin gates as the number of impeller blades on the mouth ring and boss part of the impeller, and through these pin gates, the molten resin starts flowing from the mouth ring and boss part at the same time, and flows into the gap between the main plate and the side plate. 2. The method of forming an impeller for a centrifugal fluid machine according to claim 1, wherein the impeller is filled evenly in a well-balanced manner. 3. A mold for an injection molding machine for forming an impeller of a centrifugal fluid machine, characterized in that the same number of pin gates as the number of blades of the impeller are provided on the mouth ring and boss portion of the impeller, respectively.