JPH01169099A - Casing for centrifugal projector - Google Patents

Abstract

PURPOSE:To obtain a centrifugal projector having excellent wear resistance at a low cost by a method in which a hard layer formed metallurgically from a mixture composed of wear-resistant particles, wax, and synthetic resin is formed on the face to be touched by a projecting material of a cast steel casing body. CONSTITUTION:A casing 5 with a hard layer 7 is supported by a side plate 8 on a carbon-steel tubular casing body 6 with an opening 9, and a rotor 2 having projecting blades 3 to give projecting speeds to a projecting material composed of ready-mixed concrete and a quick setter on its inner surface is set on the inside of the casing 5. A projecting section 10 is formed by inserting and connecting an oil-pressure motor 1 to turn the rotor 2 with high speeds, and the layer 7 is metallurgically formed by using a mixture composed of superhard wear-resistant particles such as WC particles, a braze such as Ni alloy or Fe alloy, and synthetic resin such as polytetrafluoroethylene, etc. Excellent wear resistance can thus be obtained and the number of exchange processes can also be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] For example, when carrying out concrete lining work in a tunnel, the present invention is capable of directing a shot material such as ready-mixed concrete to a target object using the rotational energy of a rotating blade. The present invention relates to a casing for a centrifugal projector that has excellent abrasion resistance and is used to project projecting material to the outside from an opening at high speed in a centrifugal projector.

[Prior Art] Conventionally, concrete lining has been constructed on the excavated surface of a tunnel or a steep slope, etc., for the purpose of preventing the collapse of earth, sand, rock, etc.

In this type of concrete lining construction, the key to the entire work is to harden the concrete early so that it can sufficiently protect the excavated surface, etc. Soda aluminate or Z A common method is to use a quick-setting agent such as cement, and after uniformly mixing and distributing the fresh concrete and quick-setting agent, the mixed material is projected and lined onto the tunnel wall using a centrifugal projector using the rotational energy of a rotating blade. It is being

Here, as shown in Fig. 5, the centrifugal projector consists of a rotor 2, which has projection blades 3 implanted on its inner surface for giving a projection speed to the projector, which is a mixture of ready-mixed concrete and a quick-setting agent. 2, a casing 5 provided with an opening 9 for controlling the projection direction of the projection material, a side plate 8 supporting the casing 5, It is composed of a supply section 11. After the mixture of fresh concrete and quick-setting agent is introduced into the casing 5 of the centrifugal projector, it is scraped up by a large number of projecting blades 3 installed on the inner surface of the outer circumference of the rotor 2. The lining receives high-speed rotational energy and is projected from the opening 9 of the casing 5 toward the target tunnel wall surface in the tangential direction of the outer circumference of the rotor 2 while exerting a frictional effect on the inner surface of the casing 5.

Here, the ready-mixed concrete used as the blasting material is, for example, ordinary Portland cement at 413 kg/cape, fine aggregate such as silica sand or sand (generally with a specific gravity of 2.60, F,
) 1.2.80) to 1069 kg/rri', coarse aggregate such as gravel (generally, specific gravity 2.63, F, H, 6,
85) to 538 ksr/d, water to cement ratio W/C5
It is blended at a ratio of 2%. The silica sand included in the formulation is a hard material with a Vickers hardness of 1100, and the sand has a Vickers hardness of 800. Therefore, conventionally, cast steel such as low alloy steel or high alloy steel, steel-based materials, high chromium cast iron, high chromium molybdenum cast iron, etc. have been used as the casing matrix. Methods used include forming a hardened layer on the inner surface of the casing by overlay welding, or bonding pre-sintered wear-resistant tiles to the inner surface of the casing by brazing.

[Problems to be solved by the invention] However, the entire casing is made of cast steel, steel, or
When forming a hardened layer using cast iron-based wear-resistant materials, these materials themselves are inferior in terms of wear resistance and durability, and forming a hardened layer by overlay welding requires a large number of man-hours and is difficult to form a uniform hardened layer. Furthermore, the method of brazing pre-sintered tiles to the inner surface of the casing has a high risk of peeling during use due to uneven adhesive strength, and there is a risk of peeling between each tile. There were problems such as increased contact resistance with the shot material at the stepped portion, leading to increased tile abrasion, and an effective solution was needed in terms of extending the life of the casing.

[Means for Solving the Problems] As a result of various studies aimed at solving the above-mentioned problems and obtaining a casing for a centrifugal projector that is low cost and has excellent wear resistance, the present inventors have developed a casing made of cast steel. The present invention has been completed based on the discovery that the object can be achieved by providing a casing with a special hard layer arranged on the surface of the casing base that contacts the projection material. That is, in the present invention, wear-resistant particles,
This is a casing for a centrifugal projector in which a hard layer metallurgically bonded by a mixture of brazing filler metal particles and a synthetic resin is arranged.

The casing base in the present invention conforms to JIS G 344
5 Manufactured from cast steel such as carbon #A steel pipe for machine structures.

In addition, the hard layer is metallurgically bonded by a mixture of wear-resistant particles such as tungsten carbide, brazing filler metal such as nickel alloy or iron alloy, and synthetic resin such as polytetrafluoroethylene. For example, it is preferable that the hard layer contains 50 to 75% by volume of tungsten carbide and 25 to 50% by volume of nickel alloy or iron alloy. For each combination of wear particles and synthetic resin, and brazing material particles and synthetic resin, the weight ratio of synthetic resin is 0.5.
~2.0% each was mixed separately and press-molded to form a highly flexible sheet-like product. After stacking these on the inner surface of the casing base at a predetermined blending ratio, 950%
A metallurgically bonded hard layer is formed by heat treatment at ~1250° C. for 30-90 minutes.

In the present invention, since the hard layer constructed on the inner surface of the casing is mainly composed of ultra-hard wear-resistant particles such as tungsten carbide, it is more resistant to the abrasive action of the shot material that comes into contact with it than conventional materials such as cast steel, cast iron, etc. It shows a remarkable effect in terms of wear resistance compared to steel, or to steel with a built-up welding layer of cobalt alloy or the like applied thereto.

In addition, brazing filler metals such as nickel alloys and iron alloys exhibit an excellent welding function for metallurgically bonding ultra-hard wear-resistant materials such as tungsten carbide particles to the casing matrix, as well as buffering impact effects on the hard layer. It is a combination of abilities.

Furthermore, synthetic resins mainly made of polytetrafluoroethylene are made flexible as mentioned above so that they can be placed on the construction surface of the casing with an even distribution of ultra-hard wear-resistant material and brazing material. It acts as a medium to make a rich sheet-like product.

An example of a casing for a centrifugal projector in which such a hard layer is arranged will be explained based on the attached drawings.

FIG. 1 is a perspective view showing an embodiment of the casing of the present invention;
FIG. 2 is a cross-sectional view taken along the line I--I in FIG. It is a sectional view on line -■.

The casing 5 of the present invention is constructed by forming the hard layer 7 on the casing base 6 made of, for example, a carbon steel pipe and having an opening 9 formed therein.

The casing 5 is supported by a side plate 8, and inside the casing 5, a projection blade 3 is fixed to the inner surface by bolts, etc., for giving a projection speed to the projection material, which is a mixture of fresh concrete and a quick setting agent. A projection section 10 is formed by connecting and inserting a large number of rotors 2 to, for example, a hydraulic motor 1 for high-speed rotation.

Note that it is also possible to form the projection vane 4 of the projection blade 3 with the same hard layer 7 as that applied to the casing 5 of the present invention, which is preferable from the viewpoint of improving the wear resistance of the projection blade 3.

[Example] Next, examples of the present invention will be described.

Example I JIS G 3445 carbon steel pipe for mechanical structures is used as the base material, inner diameter 400 m, wall thickness 16 mm, depth 228 mm
The inner surface of the casing base 6 for a centrifugal projector is coated with tungsten carbide particles and polytetra 1% by weight so that the hard layer 7 has 70% by volume of tungsten carbide and 30% by volume of nickel alloy. A sheet press-formed by mixing fluoroethylene and nickel brazing alloy particles containing boron (composition double weight %; C = 0.064, Cr
=16.0. Fe=1.95, Si<0.1, B=
3.5, N1=Ba1. ) with 1% by weight of polytetrafluoroethylene mixed and press-molded, and then heat-treated at 1150°C for 1 hour to form a 2.5 mm thick sheet metallurgically bonded to the inner surface. A casing 5 for a centrifugal projector having a hard layer 7 was manufactured.

This product was attached to a centrifugal projector, and as a result of projecting 10-millimeter fresh concrete at a projecting speed of 14.7 m/sec, the average abrasion loss on the inner surface of the casing 5 was 0.02 mm in the thickness direction. It was recognized that the wear life of the casing could be significantly extended compared to the conventional example.

Example 2 Brazing filler metal was made of iron alloy particles (composition double weight %: C = 3.91, C
r=0.42, Hn=0.29, HO=10.11,
N1=0.37, P=0.022, S=0.010.
5i=0.54, Fe=Ba1. ) except that a centrifugal projector casing 5 having a hard layer 7 with a thickness of 2.5 ymn was manufactured in the same manner as in Example 1, and the ready-mixed concrete was projected in the same manner as in Example 1. , the average wear loss of the inner surface of the casing 5 is 0.012 m in the thickness direction.
It was recognized that the results showed only m.

Comparative Example 1 Using the same base material as Example 1, the inner surface was c=o in weight%,
ao%, Mn=1.24%, 5i=1.65%, Cr=
3.82.

%, W=2.42%, B=0.28%, P=0.009
%, S=0.005%, Fe=Ba1. A casing with the same inner diameter as in Example 1 was manufactured by overlay welding with an alloy having the following composition and a coating layer with a thickness of 6W11 was provided,
As a result of projecting 10 m' of fresh concrete at a projecting speed of 14.7 m/sec, the average wear loss on the inner surface of the gauging was 79 mm in the thickness direction, approximately 40 times that of the casing of the present invention. It was also recognized that this has been achieved.

Comparative Example 2 Using the same base material as in Example 1, the inner surface was C=0.
25%, Hn=1.38%, 5i=o, a9%, Cr=
1.16%, P=0.010%, S=0.008%, F
e=Ba1. A casing with the same inner diameter as in Example 1 was manufactured by overlay welding with an alloy having the following composition and a coating layer with a thickness of 6 m was provided, and the casting work of ready-mixed concrete was carried out in the same manner as in Comparative Example 1. As a result, it was found that the average abrasion loss on the inner surface of the casing was as much as 3.1 in the thickness direction, indicating that 172 or more of the coating layers were worn.

[Effects of the invention] ' Since the present invention is a casing for centrifugal projectors in which a special hard layer is arranged on the inner surface of the nlA iron casing base, the average wear loss is less than 1/40th of that of conventional casings, that is, the use It has been recognized that it has extremely excellent effects, such as the lifespan being more than 40 times longer, the wear resistance being extremely excellent, and the number of replacements required being reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the casing of the present invention;
FIG. 2 is a cross-sectional view taken along the line I--I in FIG. 5 is a side sectional view showing an example of a conventional centrifugal projector. DESCRIPTION OF SYMBOLS 1... Motor, 2... Rotor, 3... Projection blade, 4... Projection vane, 5... Casing, 6...
- Casing base, 7... Hard layer, 8... Side plate, 9... Opening, 10... Projection part, 11...
・Supply Department Patent Applicant Sumitomo Metal Mining Co., Ltd. Japan Land Development Co., Ltd. Agent Osaka Welding Industry Co., Ltd.

Claims (1)

[Claims] A casing for a centrifugal projector, characterized in that a hard layer metallurgically bonded with a mixture of wear-resistant particles, brazing filler metal particles, and synthetic resin is arranged on the surface of the cast steel casing base that comes into contact with the projectile material. .