JPS6135397B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a synthetic resin blower having a metal boss inserted therein.

As a prior art, for example, a synthetic resin blower is proposed in Japanese Utility Model Publication No. 12725/1983. This blower is made by inserting a metal insert boss that is connected to the rotating shaft into a mold, then injecting a synthetic resin into the mold and molding the ribs and blades with this resin. It is manufactured as an integrated product.

During such manufacturing, if the boss is not inserted tightly into the boss mold, there is a risk that the boss will be misaligned and become eccentric with respect to the hub, and the injected synthetic resin material may leak from the gap between the boss and the mold. Because of leakage, the only way to manufacture the boss is by lathe cutting, which has particularly high processing accuracy.Therefore, it has been common practice in the past to use the boss as it is, with a cylindrical shape that necessarily has a perfectly circular outer shape.

However, the boss is made of aluminum or brass material, which is more expensive than synthetic resin material, and if it is made thinner than the specified thickness, the tap hole for screwing in the rotating shaft becomes shallower, forcing Since there is a risk of twisting due to the driving force transmitted from the rotating shaft and the wind pressure applied to the blades, there is a limit to the reduction of materials such as aluminum and brass materials, and the manufacturing cost of the blower is unavoidably high. The reality is that it continues to this day.

Therefore, as a countermeasure, the tap hole should be made deep.
In addition, in order to reduce material consumption, we proposed a boss structure with a triangular cross section, for example, with this hole as the apex, and when we studied this structure, we found that machining with a triangular cross section was impossible with lathe cutting due to its shape, so we decided to use this lathe machining. Since the only processing methods available are extrusion or extraction molding, which are extremely less precise, the outer dimensions of this boss molded product are non-uniform, and therefore, when inserting this molded boss into a resin mold, I couldn't do it〓〓〓〓〓
On the other hand, there is a risk that the connector may be inserted in a loosely loose fit, resulting in misalignment and leakage of the synthetic resin material, which is not satisfactory.

As a means for solving the above-mentioned problems, the present invention has a shaft hole for inserting a rotating shaft, and has an outer circumferential surface formed by a plurality of arcuate surfaces concentric with the shaft hole and the circumferential edges of the arcuate surfaces. A metal insert boss is formed by connecting a flat part and a tap hole communicating with the shaft hole is formed in this arcuate part, and this boss is inserted into a mold for resin molding. By injecting a synthetic resin material into the space surrounded by the flat surface and making the outer peripheral surface of the fan boss formed by the resin molded surface and the circular arc surface into a circular shape, the material of the expensive metal insert boss can be reduced. Synthetic resin with good precision allows the fan boss to have sufficient tightening strength with the rotating shaft despite the reduction in the amount of materials required, and the metal insert boss is aligned with the axis of the fan boss. This is to obtain a manufactured blower. As an embodiment of the present invention, a method for manufacturing an axial flow type synthetic resin blower will be described below based on the drawings.

Fig. 1 is a perspective view of an axial flow type synthetic resin blower manufactured by the method of the present invention, seen from the back (windward side). The rib 3, hub plate 4, and auxiliary boss 5 are formed by molding a synthetic resin material, and a metal insert boss 6, which will be described later, is integrally embedded therein.

The method for manufacturing the metal insert boss 6 is as shown in FIG. After forming a long material 11 of approximately triangular cross section and several meters in length, which has a connecting plane part and a fitting groove 10 formed in one row on the plane part, it is cut into a predetermined length ₁ as shown in FIG. 3, and then rotated. A tap hole 12 for screwing in a screw (not shown) for tightening a shaft (not shown) is formed, and then a circular arc surface portion 7, a shaft hole 13 for inserting the rotating shaft, and a groove 14 for preventing slippage are formed. It is cut and shaped using secondary processing using a lathe.

That is, as an example, the radius ₂ of the circular arc surface portion 7 is made 22.4± by primary processing by seizure or extraction molding.
0.2mm, and this radius is obtained by secondary processing using lathe processing.
₃ dimensions were cut to 22 ± 0.05 mm, and material 11, which could only obtain an accuracy of ± 0.2 mm in the primary processing, was processed to a tolerance of ± 0.05 mm and 10 in the secondary processing, including the remaining wall thickness of 0.4 mm. The shaft hole 13 is cut and finished with twice as high precision, and at the same time, the shaft hole 13 is cut with a lathe to achieve concentric precision with the arcuate surface portion 7.

Therefore, as shown in FIGS. 4 and 5, when manufacturing an axial flow type synthetic resin blower, the metal insert boss 6 processed with high precision as described above is first inserted into the lower mold 15. When the boss is inserted into the mold, the arcuate surface 7 of the boss comes into uniform contact with the inner circular wall 16 of the mold, so when the upper mold 17 is overturned and the synthetic resin material is injected and compressed from the injection port 18 as shown by the arrow, The resin material is press-fitted into the space 19 surrounded by the inner circular wall 16 and the flat part 9 of the mold 15, and further into the fitting groove 10, without leaking to the surface of the arcuate surface part 7 and going around. The blade 1, the inner and outer hubs 2a, 2
b. The above-mentioned auxiliary boss 5, together with the reinforcing rib 3 and hub plate 4, is now formed as a molded product made of synthetic resin, and the circular arc surface 7 of the metal insert boss 6 shown in FIG. The outer peripheral surface of the fan boss formed with the resin molded surface 20 is circular.

By manufacturing the fan boss using this method, the fan boss has a higher tightening strength against the rotating shaft than a conventional cylindrical metal boss having the same radius dimension ₃ as the circular inner wall surface 16 of the mold 5. The material of the metal insert boss 6 is reduced by the combined volume of the space 9 filled with synthetic resin material and the fitting groove 10, while ensuring that the tap hole 12 has the same depth dimension that can be sufficiently obtained. This can contribute to weight reduction, and the manufacturing cost is 27% in the above example.
It was confirmed that it can be done % cheaper.

In addition, during such a manufacturing process, especially during secondary processing by lathe cutting, as shown in FIG.
Even if this occurs, no problem will occur because the synthetic resin material will be pushed out into the space 19 into which it is injected, and when manufacturing is completed, the synthetic resin material will be press-fitted into the retaining groove 14. Therefore, the metal insert boss 6 does not come off in the axial direction, and since the synthetic resin material is embedded in the fitting groove 10, the auxiliary boss 5 is pulled out of the metal insert boss 6 by centrifugal force during air blowing operation. It doesn't peel off from the skin, and it doesn't peel off.
Since the fan boss consisting of both bosses 5 and 6 is circular, it does not cut the wind and cause noise like the conventional cylindrical metal boss, making it an extremely suitable axial flow synthetic resin blower. can be obtained.

In order to reduce the material used for the metal insert boss 6, as another embodiment, as shown by the two-dot chain line in FIG. If the metal insert boss 6 is formed in the material 11, the manufacturing cost can be further reduced, and the cross-sectional shape of the metal insert boss 6 may be made into a polygonal shape such as a substantially rectangular or pentagonal shape, although the material consumption cannot be reduced as much as in the above-mentioned embodiment. , at least the amount of material used can be reduced compared to the conventional cylindrical metal boss.

It goes without saying that the manufacturing method according to the present invention can also be applied to centrifugal blowers made of synthetic resin.

As described above, according to the method of the present invention, the manufacturing cost can be reduced by reducing the material used for the expensive and heavy metal insert boss, and the blower can also be made lightweight. Since it has sufficient depth to reach the shaft hole, it can be tightened with sufficient strength to the rotating shaft.

Moreover, since the arcuate surface of the metal insert boss and the inner wall surface of the mold are joined during resin molding, the metal insert boss is manufactured with good precision so that it coincides with the axis of the fan boss, and this arcuate surface portion Since the outer circumference of the fan boss, which is continuously formed by the molded surface and the resin molded surface, is circular, the fan boss will not cut through the wind and cause noise.
An excellent synthetic resin blower can be obtained.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; Fig. 1 is a perspective view of an axial flow type synthetic resin blower seen from the back, Fig. 2 is a perspective view of the material, and Fig. 3 is a metal insert boss. FIG. 4 is a cross-sectional view of a main part showing the molding process, and FIG. 5 is a cross-sectional view of FIG. 4. 6...Metal insert boss, 7...Outer circumferential circular surface part,
9...Plane part, 10...Fitting groove, 13...Shaft hole, 15...
Mold, 19... Space, 20... Resin molding surface. 〓〓〓〓〓

Claims (1)

[Scope of Claims] 1. It has a shaft hole through which a rotating shaft is inserted, and its outer circumferential surface is composed of a plurality of circular arc surfaces concentric with the shaft hole, and a flat surface connecting the circumferential edges of the circular arc surfaces. A metal insert is provided in which a tapped hole communicating with the shaft hole is formed in the arcuate surface portion, and the boss is inserted into a mold for resin molding and inserted into the space surrounded by the mold and the flat portion. 1. A method for manufacturing a synthetic resin blower, characterized in that a synthetic resin material is injected, and the outer circumferential surface of a fan boss formed by the resin molded surface and the circular arc surface portion is made into a circular shape. 2. The synthetic resin blower according to claim 1, wherein the metal insert boss circular arc surface portion and flat surface portion are formed by primary processing of press molding, and the shaft hole and the circular arc surface portion are formed by secondary processing by lathe cutting. manufacturing method.