JP2000135425A - Agitating blade of sand kneading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of the agitating blade of a sand kneading device by selecting a wear resistant material suitable to the agitation of sand and decreasing the wear at a main part at the current price or below. SOLUTION: A sand abutting surface of an agitating blade base material 1 of the agitating blade 13 of a sand kneading device agitating and kneading a material containing the sand is covered with a cermet plate 3. Further, the cermet plate 3 may be applied at the tip part, side surface and rear surface in addition to the sand abutting surface. In this way, excellent wear resistance can be obtained. Moreover, a crack is prevented from being generated by cementing the cermet plate while brazing it at the sand abutting surface of the agitating blade base material and the tip part, side surface and rear surface to cover it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sand kneading apparatus which stirs and kneads a material containing sand such as a molding sand and a binder used for casting, and more particularly to extending the life of stirring blades for kneading. Things.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, a sand kneading apparatus 10 for kneading a molding sand and a binder or the like improves the bonding strength between the molding sand fed from an inlet 14 on the left side of FIG. A kneaded material 17 composed of a heat-resistant binder for improving die-removability and the like is provided around the axis of a kneading shaft 12 which is concentrically arranged in the cylindrical trough 11 and rotated by a power 16. Due to the rotation of the stirring blade 13, the mixture is sent to the right while being kneaded, and is discharged from the discharge port 15.

The agitating blades 13 used in the sand kneading apparatus 10 are constantly abraded due to constant contact with high-hardness sand.
Since the gap with the tip of 3 becomes high pressure due to the biting of sand or the like, the tip of the stirring blade 13 is greatly worn, and the gap tends to gradually widen.

As a result, the material 17 to be kneaded adheres and accumulates on the inner wall of the cylindrical trough 11 over the thickness of the gap without being sufficiently agitated, causing spontaneous hardening. Or peel off by vibration,
When the accumulated thickness is increased due to abrasion of the tip of the stirring blade 13, it does not peel off, and has the drawbacks of reduced kneading efficiency, uneven kneading, and complicated cleaning.

[0005] As a countermeasure, an inexpensive material is used as a base material of the stirring blade, and a flat ceramic plate having abrasion resistance is screw-coated on a surface to be hit most by sand (hereinafter referred to as a contact surface of sand). A stirring blade 13 that replaces when worn is used (see Japanese Patent Application Laid-Open No. 7-100349).

The tip of the stirring blade 13 has a relatively high rotational speed (500 to 1800 rpm), and the friction speed is higher than the other portions, so that the tip portion is greatly worn. It was also found that sand wrapped around and accelerated wear.

The ceramics conventionally used are mainly alumina (hardness: HRA93), which is expected to be durable due to its higher hardness than sand (hardness: HRA83-84). It has been used because there is no alternative material other than expensive and expensive, but a material with better durability was required.

[0008] Further, the mounting of the ceramic plate,
Although screwing was used in consideration of replacement, it was difficult to replace the ceramic plate due to wear of the screw head or clogging of the screw hole with sand.

[0009] Furthermore, relatively high-speed rotation (500-1800
rpm), loosening of screws due to uneven load on the material 17 to be kneaded, cracking of the ceramic plate due to excessive tightening of screws, and collision of solids, etc., are occurring, and measures are required. Was.

[0010]

As described above, the conventional stirring blade has a ceramic plate installed locally and in a replaceable state mainly from the economical point of view. The short contact life of the sand caused by the abrasion wear and the short life of the screw, which was likely to cause cracking due to screwing, and the tip, side, and back surfaces not covered with the ceramic plate were also worn by friction with the sand.

[0011] For this reason, the selection of a wear-resistant material suitable for agitating sand, the prevention of abrasion of a portion of the agitating blade where no abrasion-resistant material is present on the tip, side and back surfaces thereof, and the provision of an inexpensive and crack-free agitating blade. Was an issue.

Accordingly, an object of the present invention is to select a wear-resistant material suitable for agitating sand and to reduce the wear of a main part at or below the current price in order to extend the life of the stirring blade as described above. It is an object of the present invention to provide a stirring blade capable of reducing the number of the blades.

[0013]

A first aspect of the present invention for achieving the above object is a stirring blade of a sand kneading apparatus for stirring and kneading a mixed material of sand and a binder. It is covered with cermet.

According to a second aspect of the present invention, the agitating blade substrate has a sand contact surface and a tip end surface further covered with a cermet.

According to a third aspect of the present invention, the side surfaces and the back surface of the stirring blade substrate are coated with cermet, as well as the sand contact surface and the tip surface.

According to a fourth aspect of the present invention, a flat cermet plate is joined to a sand contact surface of the stirring blade base by a brazing material. Unlike the local joining by screwing, the joining by the brazing material is a joining of the entire surface, so that the force is dispersed, so that the crack is extremely reduced.

According to a fifth aspect of the present invention, a cermet plate having an L-shaped cross section and covering a contact surface and a leading end surface of the stirring blade substrate with sand is joined by a brazing material.

According to a sixth aspect of the present invention, a cermet plate having a U-shaped cross section is joined to a side surface and a back surface of the stirring blade base material covered with an L-shaped cermet plate by a brazing material. The tip portion of the stirring blade substrate is covered with the cermet plate having an L-shaped cross section and the U-shaped cermet plate in a bag shape.

According to the cermet, the wear resistance is greatly improved as compared with the ceramic. In a seventh aspect of the present invention, the composition of the cermet is based on Ni and B: 0.6-3.
% By weight, Si: 0 to 6% by weight, Mo: 3 to 35% by weight,
WC: 10 to 70% by weight.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A stirring blade 1 of a sand kneading apparatus (FIG. 7).
1 and FIG. 2 which is an exploded perspective view of FIG. 1. The stirring blade having a screw 4 attached to a shaft 12 of a sand kneading device (FIG. 7) at the right end. At the left end of the base material 1, a cermet plate 3 as a corrosion-resistant and abrasion-resistant material is laminated with a brazing material 2 interposed on a surface on which the sand directly hits when the sand is agitated, and heated to form the stirring blade base material 1. The cermet plate 3 was joined.

The cermet has a material composition disclosed in Japanese Patent Application Laid-Open No. 8-67937 (Ni: B: 0.6
-3% by weight, Si: 0-6% by weight, Mo: 3-35% by weight, WC: 10-70% by weight), the wear resistance ratio with the ceramic (alumina) conventionally used (alumina wear). The wear amount when the amount is 1) is 0.45 to 0.7
2 (by abrasion test).

In this embodiment, the above-mentioned Japanese Patent Application Laid-Open No.
No. 7937, B: 2.2% by weight, Si: 3.2% by weight, M based on the range of the material composition disclosed in Japanese Patent No. 7937.
o: an alloy of 15% by weight and WC: 30% by weight were used.

The cermet plate 3 shown in FIGS.
The method of manufacturing will be described in detail. First, raw material powder having the above-mentioned alloy composition was blended and mixed and pulverized by a rotary ball mill. The molding was performed by a uniaxial pressure molding method (press molding method) using a mold. First, a powder was filled in a mold and pressurized at about 25 MPa.

Here, when the molding pressure is 20 MPa or less, the strength of the molded body is weak and may be damaged, and the wear-resistant member is greatly distorted by shrinkage during sintering. 40MP
At a molding pressure equal to or higher than a, cracks occurred in the molded body. A sintered cermet plate of the formed compact is shown in FIG. The sintering was performed by setting the compact in a furnace using a vacuum furnace and at a furnace pressure of 4 to 7 Pa and a sintering temperature of 1070 ° C.

Next, the substrate 1 of the stirring blade 13 and the corrosion-resistant
As shown in FIG. 2, a thin plate of the brazing material 2 is put between the cermet 3 after sintering and the joining surface of the base material 1 as shown in FIG. Vacuum brazing was used to prevent air mixing and oxidation.

Since the liquid temperature of the cermet plate 3 is about 980 ° C., it is preferable to use a brazing material which can be bonded at a temperature lower than the liquid temperature. From the above, the contact surface side of the stirring blade substrate 1 against the sand is covered with the cermet plate 3.

In the production, the stirring blade 13 shown in FIG. 1 was produced at 850 ° C. using silver brazing (thickness: 0.1 mm) selected from the viewpoint of strength and cost. The cost was almost the same as the conventional one.

When a built-in test was conducted on an actual machine, the wear resistance ratio was about 0.5 as compared with the conventional wear-resistant material made of ceramics (alumina), and the life was extended about twice. Although the wear-resistant material sometimes cracked, the cermet plate 3 of the present invention did not cause any breakage such as cracking or chipping.

The hardness of the casting sand, the ceramics (alumina) which is the conventional stirring blade material, and the cermet of the present invention are as follows.

・ Casting sand: 83-84 (HRA) ・ Ceramics (alumina): 93 (HRA) ・ Cermet: 85 (HRA)

That is, the hardness of the cermet used in the present invention, whose hardness is almost the same as that of the target casting sand, is at least twice as long in terms of abrasion resistance as the conventional ceramic (alumina) which is harder than the cermet. It can be considered that the cermet has been proved to be compatible with the casting sand in question.

Next, another embodiment to which the present invention is applied will be described. The stirring blades 13 in the cylindrical trough 11 are arranged not only on the circumference of the shaft 12 as shown in FIG. 8 which is a cross section taken along the line AA of FIG. 7, but also in FIG. Are located.

For this reason, in the longitudinal direction, depending on the state of the material to be kneaded, the portions of the stirring blade 13 that require corrosion resistance and abrasion resistance are not only the contact surface of the stirring blade 13 with the sand but also the tip portion, the side surface or the sand. May also be required.

First, a method for coating the contact surface and the tip portion of the sand with the cermet plate in the same manner as described above will be described with reference to FIG. 3 and FIG. 4 which is a perspective view of FIG.

In FIG. 4, the agitating blade substrate 1 is fitted between the sand contact surface side and a cermet plate 6 having an L-shaped cross section via a brazing material 5 bent into an L-shape. What was heated and joined as shown in FIG. 3 is the stirring blade 13A,
As a result, the agitating blade 13A is covered with the cermet plate 6 on the sand contact surface and the tip.

Next, the covering of the side and back surfaces of the stirring blade 13A with the cermet will be described with reference to FIGS. 5 and 6 which is a perspective view of FIG.

In FIG. 6, an assembly composed of the stirring blade base material 1, the brazing material 5 and the cermet plate 6 is the stirring blade 13A of FIG. 3, and the U-shaped brazing material 7 is inserted from the back surface of the stirring blade 13A. C-shaped cermet plate 8
Are fitted and heated and joined according to the above-mentioned production method is the stirring blade 13B of FIG.

Therefore, the agitating blade substrate 1 was covered with the cermet plate 6 having an L-shaped cross section at the contact surface and the tip of the sand, and the cermet plate 8 having a U-shaped cross section at the side and back. The tip of the stirring blade 13B is covered with the cermet plate 6 and the cermet plate 8 in a bag shape.

The cermet plate 6 and the cermet plate 8
The L-shape and the U-shape of the cross section need not necessarily be integral, and may be an L-shape or a U-shape with a plurality of flat plates. Furthermore, although the joining has been described by brazing the cermet plate material, the cermet powder may be sintered using HIP or the like and integrally formed.

[0040]

As described above, according to the present invention,
In the stirring blade of the sand kneading device, the abrasion resistance can be improved as compared with conventional ceramics because the contact surface of the sand and the coating of the tip surface, side surface and back surface are made of cermet. The composition of the cermet is based on Ni and B: 0.6 to
If the composition is 3% by weight, Si: 0 to 6% by weight, Mo: 3 to 35% by weight, and WC: 10 to 70% by weight, excellent wear resistance can be obtained. Further, cracks can be eliminated by joining and covering the cermet plate by brazing to the contact surface of the stirring blade base material, the tip surface, the side surface, and the back surface.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment according to the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a side view showing another embodiment according to the present invention.

FIG. 4 is an exploded perspective view of FIG. 3;

FIG. 5 is a side view showing still another embodiment according to the present invention.

FIG. 6 is an exploded perspective view of FIG. 5;

FIG. 7 is a sectional view of a conventional sand stirrer.

FIG. 8 is a sectional view taken along line AA of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stirring blade base material 2,5,7 Row material 3,6,8 Cermet plate 4 Mounting screw 10 Sand kneading device 11 Cylindrical trough 12 Kneading shaft 13,13A, 13B Stirring blade 14 Input port 15 Discharge port 16 Power 17 Kneading object

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 29/08 C22C 29/08 32/00 32/00 N

Claims (7)

[Claims] 1. A stirring blade of a sand kneading apparatus for stirring and kneading a material containing sand, wherein a contact surface of the sand of the stirring blade base material is covered with a cermet. 2. The stirring blade of the sand kneading apparatus according to claim 1, wherein a tip end surface of the stirring blade base is further coated with a cermet together with a sand contact surface of the stirring blade base material. 3. The stirring blade of the sand kneading apparatus according to claim 1, wherein a side surface and a back surface of the stirring blade substrate are coated with a cermet, as well as a contact surface and a front end surface of the stirring blade substrate. 4. The stirring blade of the sand kneading apparatus according to claim 1, wherein a flat cermet plate is joined to the contact surface of the sand with a brazing material. 5. A cermet plate having an L-shaped cross section covering the contact surface of the sand and the tip end surface of the stirring blade base material,
3. The joint according to claim 2, wherein the joint is formed by a brazing material.
The stirring blade of the sand kneading apparatus according to 1. 6. A U-shaped cermet plate having a U-shaped cross section is joined to a side surface and a back surface of a stirring blade substrate joined with an L-shaped cermet plate by a brazing material. The stirring blade of the sand kneading apparatus according to claim 3, wherein the contact surface of the material, the back surface, the front end surface, and the side surface of the material are covered in a bag shape. 7. The method according to claim 1, wherein the cermet is based on Ni:
0.6-3% by weight, Si: 0-6% by weight, Mo: 3-3
The stirring blade of the sand kneading apparatus according to any one of claims 1 to 6, comprising 5% by weight and WC: 10 to 70% by weight.