JPS643038Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protective cap that is fitted to the end of a tube to protect the painted surface applied to the inner surface of the tube.

Ductile cast iron pipes whose inner surfaces are powder-coated with epoxy resin, etc. are commonly used, but in order to protect the inner coating, a protective cap is fitted to the end of the pipe body to close the end of the pipe. are doing.
Conventionally, as shown in Fig. 1, for example, a bottomed cylindrical protective cap a is used, and its inner periphery is dimensionally regulated by a core with respect to the socket end of the pipe body P, so that tolerances cannot be met. Since it is small, it is fitted internally, and the outer periphery of the socket end is sized and regulated by a metal frame, and the tolerance is small, so it is fitted externally. Protective cap a is the second
As shown in the figure, it consists of a slightly tapered cylindrical part b and a closing plate part c that connects the small diameter side end part,
Projections d and inclined projections e are provided at a plurality of locations in the circumferential direction on the inner periphery of the cylindrical portion b so as to absorb dimensional tolerances. By the way, for convenience when carrying the tube p, there is a third
It is desired that a protective cap be fitted inside the tube body on the insertion side as shown in FIGS. However, the inner periphery of the insertion port must be able to absorb large dimensional tolerances since dimensional errors in the tube wall thickness are added to the outer diameter tolerances of the tube p. However, in the case where the cylindrical portion b is provided with protrusions or inclined protrusions as shown in FIG. 2, it is difficult to accommodate large dimensional tolerances, and it is not possible to satisfy such demands with a structure similar to the conventional one.

In view of the above-mentioned problems, the object of the present invention is to provide a protective cap that can be fitted inside the inner periphery of a tube end having large dimensional tolerances, and embodiments thereof will be described below with reference to FIGS. 3 to 8.

In Fig. 3, a protective cap a with protrusions similar to the conventional one is fitted into the socket of a tube body p, which has a socket and an inlet formed at both pipe ends, and a protective cap a according to the present invention is fitted to the socket. Cap 1 is fitted inside. The protective cap 1
As shown in FIG. 4, it consists of a slightly tapered fitting cylinder part 2, and a closing plate part 3 is provided at the end on the small diameter side.
are formed continuously and have a bottomed structure. An engaging portion 4 consisting of an annular collar with an L-shaped cross section that engages the end surface of the tube body P and the outer periphery of the tube end is continuously formed at the open end on the large diameter side of the fitting tube portion 2. Furthermore, on the outer surface of the fitting cylinder portion 2, a plurality of hemispherical protrusions 5 are provided protrudingly located approximately at the center in the axial direction and spaced at appropriate intervals in the circumferential direction. Height x of the hemispherical protrusion 5
is determined to be approximately equal to the radial error around the inner circumference of the tube. That is, in FIG. 5, the standard outer diameter of the tube p is D, the outer diameter tolerance on the larger diameter side is Δ ^D ₁ , the outer diameter tolerance on the smaller diameter side is Δ ^D ₂ , and the maximum wall thickness of the tube is t _nax , if the minimum wall thickness is t _nio , the maximum radius error x on the inner circumference of the tube is:
It is half the difference between the inner diameter at the maximum outer diameter and minimum wall thickness, shown by the broken line in Figure 5, and the inner diameter at the minimum outer diameter and maximum wall thickness, shown by the solid line in Figure 5, and therefore x = ^ΔD ₁ + ^ΔD ₂ /2+t _nax −t _nio .

When the protective cap 1 having the above structure is fitted into the tube end of the tube body p as shown in FIG. The portion 2 is deformed as shown by the imaginary line in FIG. 4, and the fitting is completed. At this time, the protrusions 5 are located at a location away from both the closing plate part 3 that restrains the deformation of the fitting cylinder part 2 and the engaging part 4, and have a hemispherical shape and are arranged at intervals in the circumferential direction. Since it is set up,
The fitting cylindrical portion 2 is elastically easily deformed, making it easy to fit and securely fit.

In addition, although FIG. 3 shows the case where the protective cap 1 is fitted to the insertion end of the tube body P, which has a socket and an insertion port formed at each end of the tube, the applicable locations are not limited to this. For example, as shown in FIG. 6, there is a use row in which protective caps 1 are fitted into both ends of a tube body p having a joining flange f at one or both ends.

7 and 8 show the structures of protective caps for small diameter pipes and for medium and large diameter pipes, respectively. In the case of a small diameter, three hemispherical protrusions 5 are provided, but in the case of a large diameter (for example, 200 mm or more in diameter), a large number (for example, six) are provided.

According to the protective cap of the present invention, as is clear from the above description, when the protective cap is fitted into the end of the tube, the protrusion provided on the resin fitting cylinder is pressed against the inner surface of the tube. Since the fitting cylinder is elastically deformed, it is possible to obtain a large amount of deformation, and even if there is a large error in the inner diameter of the tube end, it can be easily followed and fitted inside. The elasticity of this fitting cylinder allows it to be reliably attached to and held at the tube end. In addition, since the engaging portion engages both the end surface of the tube and the outer periphery of the end, the engaging portion can also prevent the tube from falling off from the tube end, and can be attached to the tube end. Not only can retention properties be improved, but also the end surface and outer circumferential surface of the tube end can be protected by the engaging portion. Furthermore, since the tube end can be closed by the closing plate, it is possible to prevent dust, dirt, etc. from entering the tube and reliably protect the powder coating on the inner surface of the tube. Since the tubes are placed at a distance from each other, it is possible to place hands or engage the inside of the tube end with a jig, making it easy to carry the tube, and to join the tube and insert it into the tube. Removal work before water flow is also easy.

[Brief explanation of the drawing]

Fig. 1 is a half-cut vertical cross-sectional view showing a conventional tube end closed state, Fig. 2 is a partially broken longitudinal cross-sectional view of a conventional protective cap, and Fig. 3 is a tube body using the protective cap according to the present invention. FIG. 4 is a partially enlarged vertical sectional view of the protective cap according to the present invention; FIG. 5 is an explanatory diagram of the height setting of the hemispherical protrusion;
Fig. 6 is a half-cut vertical sectional view showing another example of use of the protective cap according to the present invention, Fig. 7 shows the specific structure of the protective cap for small diameter pipes, a is a longitudinal sectional front view, b is a left side view, The figures show the specific structure of a protective cap for medium and large diameter pipes, in which a is a longitudinal sectional front view, b is a half-cut right side view, and c is a half-cut left side view. 1...Protective cap, 2...Mating cylinder part, 3...
Closing plate portion, 4...engaging portion, 5... hemispherical protrusion.

Claims (1)

[Scope of utility model registration request] A fitting tube that fits into the inner periphery of the tube end, a closing plate that has a bottom at one end of the fitting tube, and a fitting tube that is spaced apart from the closing plate in the axial direction. an annular flange-shaped engagement part formed on the other end opening side of the fitting part to engage with the end surface of the tube body and the outer periphery of the end part; and a plurality of circumferential positions approximately at the axial center of the outer peripheral surface of the fitting cylinder part and a protrusion that is formed in a solid hemispherical shape and is pressed by the inner surface of the tube to elastically deform the fitting tube inward in the radial direction when the fitting tube is fitted into the inner circumference of the tube. A protective cap with a painted inner surface of the tube body, characterized by being made of resin.