JPS6299080A - Metal grain for grinding/polishing/cleaning - Google Patents

Abstract

PURPOSE:To improve anticorrosion and grinding/polishing/cleaning performance by forming crushed grains containing specific weight % of Cr, C and Si in grain size of 210-2,000mu. CONSTITUTION:A bowl-shaped metal chip, which has composition consisting of Cr: 16-20%, C: below 2% and Si: 1-7% by weight together with residual Fe and unavoidable impurity, is placed between a percussion ring 9 and a cylindrical block 10 in the vessel 8 of a disk mill and a lid 11 is attached thereto. Then, said mill is vibrated in the horizontal direction so as to crush the bowl- shaped metal chip by impulse force caused by collision of the ring 9 to the cylindrical block 10 in the vessel 8, so that metal grains for grinding/polishing/ cleaning is to be obtained in grain size of 210-2,000mu.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to abrasive metal particles, and the abrasive metal particles according to the present invention have corrosion resistance and can be used for aluminum die casting, zinc die casting, casting, etc. It is used as an abrasive for shot blasting casting surfaces, and also for air blasting molds and other metal surfaces.

(Prior Art) Stainless steel cut wires and stainless steel beads have conventionally been used as corrosion-resistant abrasive metal particles.

(Problems to be Solved by the Invention) Stainless steel cut wires have a minimum particle size of around 300 microns due to difficult cutting techniques;
There was a problem in that it was difficult to supply particles smaller than 0 microns, and the price increased significantly as the particle size became smaller. In addition, stainless steel beads are more expensive than cut wires, and they have a short lifespan as an abrasive because they have cavities inside. The present invention solves the problems of the conventional abrasive materials mentioned above, and provides inexpensive metal particles with a particle size of 210 to 2000 microns that have corrosion resistance and a lifespan equal to or longer than that of stainless steel cut wire. purpose.

(Means for Solving the Problems) The present inventors have focused on mechanically crushing thin metal chips with a thickness of about 0.3 mm as a means of manufacturing metal particles at low cost. Such a thin metal chip can be manufactured at a relatively low cost, for example, by the method described in the specification of Japanese Patent Application No. 59-60384 entitled ``Flat Metal Chip, Method and Apparatus for Manufacturing the Same''.

However, when a conventional crushing test was conducted on Fe-Cr metal chips having corrosion resistance, it was almost impossible to crush them. Therefore, as a result of testing the grindability by changing the chemical composition, Figure 1 shows the content of C and Si in the metal chips and the percentage of particles passing through a 63-micron sieve when the metal chips are ground for 5 minutes in a disc mill. As shown in the relationship between C and Si, it was found that both C and Si have the effect of improving the crushability of metal chips.

Furthermore, Table 1 shows the relationship between the chemical components and the time until induction when the particles obtained in the crushing test were left immersed in an aqueous solution with a chloride ion concentration of 11,000 pp.

As is clear from Table 1, it was found that St 2 and Cr improve corrosion resistance, and in the range of Si 1.0% or more and Cr 16% or more, C does not occur up to 2.0%.

The present invention was made based on these new findings, and the abrasive metal particles according to the present invention have Cr:
16-20χ, C: 2% or less, Si: 1-7χ,
The pulverized particles have a composition consisting of residual Fe and unavoidable impurities, and are characterized by having a particle size of 210 to 2000 microns.

Next, the reason for the limit on the component range of metal particles according to the present invention will be explained.

Based on the knowledge that Cr does not induce up to 0.2% in the range of 16% or more, the lower limit was set at 16%, and the upper limit was set at 22% from the economic point of view.

The upper limit of C was set to 2% based on the knowledge that Cr of 16% or more does not induce C in a range of 2% or less.

Si is in the range of 1% or more, Cr is 16% or more, 02%
The lower limit was set at 1% in order to reduce the risk of induction and to facilitate pulverization, and the upper limit was set at 7% from the economic point of view.

Next, a method for producing metal particles for polishing according to the present invention will be briefly explained.

Molten metal having the above composition is melted and placed in the melting tank 1 of the apparatus shown in FIG. The tip of a bowl-shaped protrusion 3 provided on the outer periphery of a rotating drum 2 made of high-quality copper and having a diameter of about 300 fins is inserted into the molten metal 4.
The temperature of the molten metal is adjusted by the heating element 5, and the level adjustment block 6 is raised and lowered into the molten metal 4 to adjust the molten metal level, and the rotating drum 2 is rotated at 200 to 300 rpm.
The molten metal adhering to the tip of the protrusion 3 is at least partially solidified by rotating at a rotational speed of approximately rn, and is peeled off from the protrusion to form, for example, a bowl having a thickness of Q and approximately 3 m as shown in Fig. 3. A shaped metal chip 7 is manufactured.

The flaky metal chip 7 thus produced was placed between the striking ring 9 and the cylindrical block IO in the vessel 8 of a hard high manganese steel disc mill shown in FIG.
After installing the ll, vibrate it horizontally, thereby
The bowl-shaped metal chips are crushed by the impact force caused by the collision between the ring 9 and the cylindrical block 10 in the vessel 8, and
After passing through a 0 micron sieve, it can be passed through a 210 micron sieve to obtain abrasive metal particles according to the present invention on the sieve.

The metal particles according to the present invention are not limited to the manufacturing method described above, and can of course be manufactured using other suitable methods and devices. For example, rotary ball mill, vibration mill,
A hammer mill, stamp mill, etc. can be used, and metal particles of a desired particle size can be easily obtained depending on the mechanical grinding time.

The grinding time of the abrasive metal particles according to the present invention is, for example, 3.6.
Examples A, B, and C of the particle size structure after 9 hours are shown in FIG.

As shown in FIG. 5, the particle size of the particles can be freely selected by selecting the grinding time. Therefore, according to the present invention, it is possible to easily supply metal particles finer than 300 microns, which was difficult to supply using a stainless steel cant wire.

Example SOS 430 scrap material, Fe-5i, Fe-C
Using R5 carbon powder, the composition was adjusted and a molten metal having the composition shown in Table 2 was produced using a high frequency induction furnace.

Table 2 This molten metal was heated to a diameter of 1 to 2 f using the equipment shown in Figure 2.
A bowl-shaped metal chip with a thickness of 0.3 mm was used.

Next, the metal chips were ground for 1 to 24 hours using a disk mill shown in FIG. 4, and the resulting particles were sieved.

An example of the particle size structure of the obtained metal particles is shown in Table 3.

Table 3 As is clear from Table 3, the metal particles according to the present invention have uniform particle sizes and fully satisfy S40 of JIS G5903.

Table 4 shows the results of a comparison test of the life of the obtained metal particles as an abrasive with commercially available stainless steel beads. The test method was to continuously project the test sample at a projecting speed of 63 m/sec, and calculate the number of projections until the residual rate on the sieve of a predetermined sieve (1/2 of the particle size of the test material) reached 45χ, which was determined as the life value.

Table 4 The metal particles according to the present invention were able to provide an abrasive life three times longer than commercially available stainless steel beads.

Table 5 shows the results of a comparative test of the surface finish when the metal particles according to the present invention were used as an abrasive in aluminum die casting with a commercially available stainless steel cut wire. The test method was to project the sample material at a projection speed of 50 m/sec,
The surface roughness of polished aluminum die-casting is determined by JISB-06.
Measured based on 01.

As is clear from Table 5, the metal particles of the present invention can obtain the same surface roughness as the stainless steel cant wire of the same particle size under the same projection test conditions, and have the same cleaning effect. was recognized.

(Effects of the Invention) As explained above, the metal particles for polishing according to the present invention can be easily obtained by freely selecting the particle size up to 210 micron particle size, which was difficult to obtain with conventional stainless steel cut wires. Moreover, it has a particle size structure that satisfies JIS, is corrosion resistant, has a life span as an abrasive material several times longer than that of stainless steel beads, and can be easily manufactured and provided at low cost.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the C and Si contents in Fe-Cr metal chips and pulverization properties, and Fig. 2 shows an example of the equipment used to produce the metal pulverization for shots of the present invention. 3 is a perspective view of a metal chip produced by the apparatus shown in FIG. 2, FIG. 4 is a vertical cross-sectional view of a disc mill used to crush the metal chips, and FIG. 5 is a grinding machine according to the present invention. It is a graph showing the relationship between grinding time and particle size of sweeping metal particles. 1... Melting tank 2... Rotating drum 3...
・Protrusion 4... Molten metal 5... Heating element 6... Level adjustment block 7... Metal chip 8... Disc mill vessel 9... Hitting ring 10... Cylindrical block 1
1... Lid patent applicant: Nippon Yakin Kogyo Co., Ltd. Representative Patent Attorney: Akira Sugimura, Patent Attorney: Oki Sugimura Figure 1 Si% Figure 2 Moxibustion

Claims (1)

[Claims] 1. By weight, Cr: 16-20%, C: 2% or less, Si
Metal particles for polishing, characterized in that they are pulverized particles having a composition of: 1 to 7%, residual Fe and unavoidable impurities, and have a particle size of 210 to 2000 microns.