JP2843357B2 - Non-slip type manhole cover and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cast iron manhole cover for covering an opening on a road surface, in particular, a non-slip type manhole cover provided with a slip prevention function at a predetermined portion of its surface, It relates to a method for producing it advantageously.

(Background Art) At present, cast iron manhole covers are generally installed at openings formed for sewers, drainage holes, various burial facilities, etc. on road surfaces made of asphalt, concrete, and the like. .

In such a manhole cover, when there is a difference between the frictional resistance of the manhole cover and the frictional resistance of the road surface on which the manhole cover is arranged, for example, in rainy weather, a slip occurs when the vehicle is running, and an accident occurs. Because of this danger, usually, consideration is made to provide a predetermined uneven pattern or pattern on the surface of the manhole cover to make the frictional resistance of the manhole cover surface close to that of the road surface.

However, when such a manhole cover is made of cast iron, if it is in an as-cast state, its surface is uneven, and its frictional resistance is large. However, if the surface of the manhole cover is worn out and smoothed by the traffic of a car or a person, the resistance is lost, and the difference in the frictional resistance with the road surface is increased, and there is a risk that the slip is promoted.

On the other hand, as a manhole cover considering slip prevention,
Although it is considered that the surface of the cast iron lid is filled with resin containing sand particles, etc., this is because the resin is a form that wraps the sand particles, so the bonding force between the sand particles and the resin is low. It was weak and had poor durability.

(Solution problem) Here, the present invention has been made in view of such circumstances, and the problem to be solved is to provide an arbitrary frictional resistance according to the road surface to be deployed. An object of the present invention is to provide a non-slip type manhole cover made of cast iron, which is excellent in wear resistance and durability, and a method for advantageously producing the same.

(Solution) In order to solve the above problems, the present invention provides a cast iron manhole cover for covering an opening on a road surface, wherein a cast iron structure of a surface layer of the manhole cover includes:
The gist of the present invention is a non-slip type manhole cover characterized in that solid particles having more wear resistance than cast iron are distributed and a particle distribution layer is formed at a predetermined depth.

Further, in the present invention, when manufacturing such a manhole cover, in the casting cavity of the mold, so as to be located at a predetermined portion of the surface of the formed manhole cover,
The pouring is performed by disposing a porous insert having a predetermined thickness in which solid particles having higher wear resistance than the cast iron are bonded, pouring the molten cast iron into the casting cavity, and allowing the mold to be suctioned under reduced pressure. The gist of the present invention is that the molten cast iron is introduced into the porous insert so that a layer in which the solid particles are distributed in the structure of the cast iron is formed on the surface of the manhole cover.

(Specific Configurations / Examples) In order to clarify the present invention more specifically,
Embodiments of the present invention will be described in detail with reference to the drawings.

First, as shown in FIGS. 1 (a) and 1 (b), a manhole cover 2 according to one embodiment of the present invention has a disc-shaped manhole cover main body 4 made of cast iron and a predetermined depth on an upper surface thereof. And a particle distribution layer 6 provided at
When the manhole cover 2 is disposed on a road surface, the particle distribution layer 6 forms substantially the same surface as the road surface. In addition,
Reference numeral 8 denotes a reinforcing rib formed on the back surface of the manhole cover 2.

The particle distribution layer 6 is composed of solid particles 26 having better wear resistance and higher durability than the cast iron constituting the manhole cover main body 4, and examples of the solid particles include alumina, zirconia, and the like. High-hardness, angular particles such as ceramic sand and sand particles are appropriately employed. And the particle size of these solid particles is appropriately set according to the desired wear coefficient of the manhole cover, but generally a particle size of about 0.1 to 3 mm is used,
Also, the shape thereof is appropriately selected so as to obtain a desired frictional resistance. Further, the depth of the particle distribution layer 6 is appropriately set according to the frictional resistance of the road surface such as Alfalt or concrete or the thickness of the manhole cover 2 where the manhole cover 2 is to be provided. Is desirable.

In the manhole cover 2 having such a configuration, the particle distribution layer 6 formed on the surface of the manhole cover 2 has a desired friction due to the kind, size, shape, etc. of the solid particles 26 constituting the particle distribution layer 6 being selected in advance. Since the particles have a resistance, the friction coefficient of the manhole cover 2 provided with the particle distribution layer 6 on the surface thereof can be made closer to the frictional resistance of the road surface on which the manhole cover 2 is provided. Even if it is arranged at a predetermined position to cover, no slip is caused due to the difference in frictional resistance between the road surface and the surface of the manhole cover 2, and the particle distribution layer 6 is formed with a predetermined depth. Therefore, even if the surface is worn, there is no problem in the frictional resistance of the particle distribution layer 6.

By the way, when manufacturing the manhole cover 2 according to the present invention as described above, it is performed using a mold as shown in FIG.

That is, first, using a green mold sand, or a self-hardening molding sand using a resin as a curing medium, and the like, using a mold composed of an upper mold 10 and a lower mold 12 produced by a commonly used casting method, A porous insert 16 having a predetermined thickness for forming a particle distribution layer (6) of the manhole cover (2) is formed in a casting cavity 14 formed by the inner surface and having the outer shape of the target manhole cover (2). And the manhole cover (2). In addition, if necessary, the upper mold 10 and the lower mold 12 are subjected to a predetermined coating on the inner surface of the casting cavity 14 according to a conventional method.

By the way, the porous insert 16 is made to have a predetermined shape (here, solid particles such as sand particles and ceramic particles), which is more wear-resistant than cast iron, by using an inorganic binder such as water glass or a phenol resin. Then, a disk shape smaller in diameter than the manhole cover)
It is a porous material in which the gap between each particle is a communication space. The solid particles may be bonded so that the solid particles do not fall from the porous insert 16 to be formed and that the desired shape can be maintained.

Then, in a state where the porous insert 16 is supported at a predetermined position in the cavity 14 by appropriate means such as a predetermined support member (not shown),
The molten cast iron is poured into the cavity 14 through the gate 20 and the runner 22.

At that time, mold (10,12)
In a sealed state by covering with a predetermined film, etc.
The suction is performed under reduced pressure using a means such as a vacuum pump. As a result, the poured cast iron melt sufficiently enters the porous insert 16 and binds the solid particles 26 so that the porous insert 16 maintains a desired shape as shown in FIG. While the binder is lost, the molten cast iron 28 penetrates into the gaps between the solid particles 26. Then, by cooling and solidifying the molten cast iron 28,
Solid particles 26 and molten cast iron 28, ie, manhole cover body (4)
Thus, the target manhole cover (2) having the particle distribution layer 6 formed at a predetermined depth, which is firmly bonded to the cast iron structure constituting by the above, is obtained. In this figure, reference numeral 24 denotes a predetermined coating die applied to the cavity forming surface of the lower die 12.

In this manner, the predetermined distribution layer 6 can be easily provided at a predetermined portion of the surface of the obtained manhole cover (2), and the solid particles 26 are bonded to the cast iron structure by physical bonding by baking. Therefore, the manhole cover (2) having extremely excellent durability can be obtained.

Further, another embodiment of the present invention is shown in FIGS. 4 (a) and 4 (b). In this case, the manhole cover 32 as another embodiment of the present invention has a manhole cover main body 34 and particles formed of solid particles having good abrasion resistance as described above, which are distributed in a predetermined pattern on the surface thereof. Distribution layer 3
, And such a particle distribution layer 36
Are formed so as to have depths set in accordance with the intended frictional resistance of the manhole cover 32, respectively.
Reference numeral 38 denotes a reinforcing rib formed on the back surface of the manhole cover main body 34. In this embodiment, the particle distribution layer 36 projects from the surface of the manhole cover main body 34 at a predetermined height, but there is no problem with the projection height as to the flushness with the road surface. It will be selected appropriately to the extent.

When the manhole cover 32 is manufactured, the upper mold 40 and the lower mold 42 are used in the same manner as in the above-described mold.
As shown in the figure, the lower mold 42 has a recess 40a for positioning so that the porous insert member 46 serving as the particle distribution layer 36 can be arranged at a predetermined position.
They are provided according to the desired pattern and shape.
In addition, a predetermined coating mold 44 is applied to the casting cavity 48 forming surfaces of the upper mold 40 and the lower mold 42 in the same manner as described above.

In the cavity 48 formed by the inner surfaces of the upper mold 40 and the lower mold 42, a porous insert member 46 having a shape corresponding to the recess 40a is disposed in each of the recesses 40a, In the same state as described above, the molten cast iron is poured in a state of being fixed by a supporting member or the like, and the molds (40, 42) are suctioned under reduced pressure using ordinary means, and then cooled and solidified. The intended manhole cover 32 is obtained.

In the manhole cover 32 thus obtained, the particle distribution layer 36 made of wear-resistant solid particles is distributed in a desired pattern and at a predetermined depth in the cast iron structure of the manhole cover body 34. Therefore, similarly to the above, the particle distribution layer 36 is formed at a predetermined depth even if it is disposed on the road surface and the surface thereof is worn out, as well as having excellent wear resistance and durability. Thus, the area occupied by the particle distribution layer 36 exposed on the surface of the manhole cover 32 does not change, so that the frictional resistance can be effectively prevented without any reduction.

In addition, in the present embodiment, since the pattern of the particle distribution layer 36 exposed on the manhole cover surface can be easily set, the shape of the manhole cover surface is adjusted so as to have a frictional resistance corresponding to the road surface. Can be formed.

As mentioned above, the specific configuration and the embodiment of the present invention have been described in detail. However, the present invention is not to be construed as being limited by the above description, and those skilled in the art may use the same unless departing from the spirit of the present invention. Various changes based on the knowledge of
Modifications, improvements and the like can be made.

For example, in the above embodiment, when manufacturing a non-slip type manhole cover according to the present invention, the mold is suctioned under reduced pressure according to a normal vacuum casting method, but in the present invention, the vacuum suction of the entire mold is performed. Alternatively, it is also possible to vacuum-suction only at least the side where the porous insert member is arranged.

Further, in the present invention, in addition to the production by the reduced pressure casting method, it is also possible to adopt a casting method by a combination of a normal reduced pressure molding method and a full molding method. That is, in such a case, on the upper surface of the vanishing model, which is made of a predetermined resin and has the outer shape of the target manhole cover main body, at a portion where a particle distribution layer is formed, a porous material of a predetermined shape made of the same solid particles as above. After placing the pliable insert, a film (thin film) is brought into close contact with the surface of the model, and is buried in mold sand such as self-hardening mold sand. It is. Next, a predetermined molten cast iron is poured into the model portion to eliminate the inorganic binder binding the model and the solid particles, and a particle distribution layer is formed at a predetermined portion by the molten metal filled in the disappeared portion. Thus, a manhole cover having a desired shape is obtained.

(Effects of the Invention) As is clear from the above description, in the non-slip type manhole cover according to the present invention, a solid portion having better wear resistance than cast iron constituting the manhole cover main body is provided at a predetermined portion of the surface. Since it has a particle distribution layer composed of particles at a predetermined depth, it has excellent wear resistance, and even if its surface is worn, the frictional resistance does not decrease, and the road surface on which the manhole cover is disposed. Can be effectively prevented from slipping.

Further, according to the present invention, when manufacturing such a non-slip type manhole cover, the porous insert forming the particle distribution layer is arranged at a predetermined position in the cavity of the mold, and the molten cast iron is poured, and the mold is poured. By suction under reduced pressure, the poured cast iron molten metal is allowed to enter the porous insert, and the solid particles constituting the porous insert are well distributed in the cast iron structure. Are firmly bonded to each other, so that a manhole cover having good wear resistance and excellent durability can be advantageously obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) and 1 (b) are a plan view and an A-A cross-sectional view, respectively, showing an embodiment of a non-slip type manhole cover according to the present invention. FIG. 2 is a sectional explanatory view in which a porous insert is arranged in a mold used for manufacturing the manhole cover shown in FIG. 1 according to the present invention, and FIG. 3 is a view showing the porous insert during casting. FIG. 4 is a partially enlarged explanatory view showing a combined state of a molten iron and a cast iron to be poured. FIGS. 4 (a) and 4 (b) are a plan view and a sectional view taken along line BB, respectively, showing another embodiment of the present invention, and FIG. 5 is shown in FIG. FIG. 3 is an enlarged partial cross-sectional view showing a state in which a porous insert is arranged in a mold used for manufacturing a manhole cover. 2,32: Manhole cover 4,34: Manhole cover body 6,36: Particle distribution layer 10,40: Upper mold, 12,42: Lower mold 14,48: Cavity 16,46: Porous insert 24,44: Paint Mold layer, 26: solid particles

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) E02D 29/14 B22D 19/00

Claims (2)

(57) [Claims] 1. A cast iron manhole cover for covering an opening in a road surface, wherein solid particles having wear resistance more than cast iron are distributed in a cast iron structure of a surface layer of the manhole cover. A non-slip type manhole cover, wherein a particle distribution layer having a predetermined depth is formed. 2. A porous insert having a predetermined thickness in which solid particles that are more wear-resistant than cast iron are bonded so as to be located at a predetermined position on the surface of a manhole cover formed in a casting cavity of a mold. By disposing the cast iron in the casting cavity and pouring the mold under reduced pressure, the poured molten cast iron enters the porous insert, and the solid particles enter the cast iron structure. A method for manufacturing a non-slip type manhole cover, wherein a distributed layer is formed on a surface portion of the manhole cover.