JPS6322273A - Sintered abrasive body - Google Patents

Abstract

PURPOSE:To prevent a failure in abrasive grain uniform distribution and an omission of abrasive grains from occurring, by molding and sintering a flat, curled fine metallic short fiber, to be obtained out of grinding a parent metal together with abrasive grains as a binding material. CONSTITUTION:A parent metal (for example, nodular graphite cast iron) is ground by a grinding stone, securing a curled, namely, bent flat striplike the metallic fiber 1. Abrasive grains 2 including the specified quantity of diamond or the like are mixed in this short fiber 1, and when they are mixed and dispersed by a stirrer or the like, as in illustration, each short fiber 1 gets intertwined so complicatedly and contacted with each other whereby a very fine mesh multilayer reticulate skeletal body 3 is formed, and these abrasive grains 2 are dispersed and charged in the fine void 4, forming a mixture 5 of the short fiber 1 and the abrasive grain 2. This mixture 5 is charged in a metal mold, and when it is pressurized, each abrasive grain 2 is firmly wrapped and held in an inner part, where a binding material is curved and bent, in this fine void 4, thus these abrasive grains are dispersed and set up in a state of being uniformly distributed. Next, they are taken out of the metal mold and sintered, thus these abrasive grains 2 are strongly deposited to the skeletal body 3 as one body.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an abrasive body such as a grinding wheel used in grinding work to process a workpiece into a required shape and size, and in particular, it relates to an abrasive body such as a grinding wheel used for grinding a workpiece into a desired shape and size, and in particular, The present invention relates to a sintered abrasive body using fine short metal fibers as a binder, which is used for grinding of brittle materials.

(Prior art) Generally, as an abrasive body for processing a workpiece into the required shape and dimensions and finishing the surface with a good smooth surface, abrasive grains such as diamond, CBN, fused alumina, and silicon carbide are used. It is formed by solidifying with a suitable binding material such as a binding material, a synthetic resin binding material, a metal binding material, etc. Among these, metal binders made of metal powders such as iron metals or copper alloy metals such as bronze and brass are mainly used as binders for high-performance abrasive grains such as diamond and CBN due to their bonding strength. There is. The abrasive body made of these powdered metal binders is
Although it is manufactured by electrodeposition or sintering with the addition of appropriate auxiliary agents as necessary, the content of abrasive grains is limited, making it difficult to improve polishing performance, and the dispersion of abrasive grains The polishing properties and retention are not good, and the abrasive body wears, mechanical strength,
There were problems with grinding resistance, etc. Therefore, recently, the aspect ratio of the base material manufactured by chatter vibration cutting is approximately 4 to 70.
The development of a fine metal short fiber sintered abrasive body using fine metal short fibers as a bonding material and using a sintered Mi weave of the fine metal short fibers as a skeleton to disperse and embed abrasive grains is underway. In this case, the production of fine short metal fibers by chatter vibration cutting involves rotating a base metal block in the shape of a column or rod, or rotating an elastic tool with a high natural frequency around the base metal. It actively generates chatter vibration while applying a predetermined amount of minute feed, and for each chatter cycle, the surface layer of the base material is forcibly divided into fibers, and the number and cutting width correspond to the vibration frequency. Fine short metal fibers with uniform dimensions and physical properties are produced. The fine metal short fibers produced by chatter vibration cutting have a strength greater than that of the base material due to work hardening, and since they are separated directly from the block in a dry process, they have high surface bonding activity and are free from oxides and other substances. There are few foreign substances. The cross section has a substantially triangular shape consisting of a smooth surface, a fractured surface, and a rough surface, and has a large surface area. However, the fine metal short fibers produced by chatter vibration cutting have lower fluidity than particles, so if they are long and thin, the fibers will become too entangled, forming a lump called a fiber ball, and the abrasive grains will Effective dispersion and encapsulation cannot be achieved. On the other hand, if the thickness is made too short and thick, the moldability and sinterability will decrease because it will become close to particles, and a high content of abrasive grains will not be achieved, so these points should be taken into account. The aspect ratio of the fine short metal fibers produced by chatter vibration cutting is approximately in the range of 4 to 70.

(Problems to be Solved by the Invention) However, with the abrasive body as described above, it is difficult to manufacture fine metal short fibers as a binding material by a chatter vibration cutting method, and chips etc. for chatter vibration cutting are difficult to manufacture. This causes severe tool wear, and the economic limit for using diamond as a metal bonding material for abrasive bodies using diamond as an abrasive is an equivalent diameter of 20 μm or more. In addition, the fine metal short fibers obtained by chatter vibration cutting, for example, each fiber has a linear shape, as shown in the example of the chatter vibration cutting of spheroidal graphite cast iron (FCD 50) shown in Fig. 4. The multilayer network-like skeleton formed by fine short metal fibers is easily collapsed, resulting in poor uniform distribution of abrasive grains in the molded product obtained by mixing with abrasive grains and molding, resulting in abrasive grains falling off and high pressure being required for high-density molding. There are various problems such as.

(Means for Solving the Problems) The present invention was completed with the aim of producing a sintered abrasive body using fine short metal fibers as a binder, which does not have the above-mentioned problems. It is characterized by being formed and sintered with abrasive grains using flat curled fine short metal fibers as a binder.

(Function) A sintered abrasive body using such fine short metal fibers as a binder can be used in the same way as a conventional abrasive body.

(Example) Next, the present invention will be explained in detail together with its manufacturing method with reference to the drawings. Fig. 1 is an enlarged perspective view showing an example of fine metal short fibers when cast iron is ground as a base metal. In the figure, fine short metal fibers (11 are curled, that is, gently curved or bent flat strips as shown in the figure, have an equivalent diameter of 1 to 20 μm, and an arc length of about 0.1 to 1.5 N). This fine short metal fiber (1) has a fibrous shape.
shows different properties by changing the grinding conditions and the grain size of the grinding wheel used for grinding. For example, the base metal is spheroidal graphite cast iron (FCD 50), and the grinding wheel used for grinding it has a diameter of 1501 mm, width of 30 mm, and grain size. In the case of wet grinding using a #80 CBN electrodeposited grindstone at a grinding speed of 1484 m/min, fine short metal fibers (1 ) is obtained. It should be noted that cutting with a cutting tool can also be used to cut into a curled shape.
Fine metal short wA with an equivalent diameter of m! (It is technically and economically difficult to obtain 11, and FIG.
3) shows a state in which abrasive grains (2) are dispersed and encapsulated in fine metal short fibers (1) produced as described above.
After classification using a specified classifier, degreasing and cleaning are performed, followed by reduction and tempering treatment. Thereafter, a predetermined amount of abrasive grains (2) such as diamond or CBN are added to the fine short metal fibers (1), and mixed and dispersed using an appropriate mixer or the like. Through this operation, the fine metal short fibers (1) intertwine and come into contact with each other in a complicated manner, as shown in Figure 2, and are raked to form a thin, multilayered mesh-like skeleton (3), and the mesh Abrasive grains (2) are dispersed and filled in a large number of micro voids (4) shown, and a mixture of fine short metal fibers (1) and abrasive grains (2) is formed.
5). Next, a predetermined amount of the mixture (5) is measured, filled into a required mold, and pressure-molded at a predetermined pressure. The pressure applied at this time is low because the binder is not powder particles but flat curled fine metal short fibers (1), so it is molded into the desired shape with low pressure, and each abrasive grain (2) is Zero-order particles are firmly contained and held in the curved or bent inner part of the bonding material in part (4) and are dispersed in a uniformly distributed state;
The molded product thus formed is demolded from the mold, transferred to a suitable support or container, and then sent into a firing kiln. The strength of the compact is relatively high due to the complex intertwining of the short metal fibers (1), so handling operations such as removal from the mold, transportation, and transfer are easy, and no damage occurs during these handling operations. do not have. When sintering is performed in the firing kiln, the skeleton bodies (3) formed by the short metal fibers +11 are welded to each other, and the abrasive grains (2) uniformly dispersed in the skeleton body (3) are also welded together. 3), and the remaining micro voids (4) between the skeletons (3) become many pores, forming a predetermined sintered structure. The body is finished into a predetermined shape and size as required and used as a product such as a whetstone. In addition, when mixing and dispersing the fine short metal fibers (1) and the abrasive grains (2), an appropriate auxiliary agent may be mixed as necessary. It can also be applied to materials and sour powder composite sintered products.

Next, the performance results of the thus obtained sintered abrasive body according to the present invention and various conventional abrasive bodies are shown in the table below. In this case, the grinding conditions are such that the circumferential speed of the grindstone as a product is 636
m/win, grinding width 3.0, depth of cut 3.0f
i, the feed rate was 42tm/ll1n, and both were ground using diamond abrasive grains, the grain size was SD#100/1, and the concentration was 100.
It is. In addition, the grinding ratio is the value obtained by dividing the removed volume of the processed product by the worn volume of the abrasive body (grinding wheel), that is, the processing removal ability per unit consumption of the grinding wheel.The larger the value, the longer the life of the grinding wheel. It shows that it has grinding ability.

According to this table, I lacks strength and resin seizure occurs under these grinding conditions, making it unusable. Similarly, ■ also lacks strength, and the grinding resistance is low in the early stages of grinding. However, after the abrasive grains wear out, the grinding resistance is large, and re-drenching is more difficult than with the grindstones marked ■ to ■ in the table. It is defective. ■ has good grindstone strength and high grinding efficiency, and has excellent properties as a whole, but ■, which is an example of the present invention, has even higher grindstone strength than ■, excellent formability, and It has good sinterability, good abrasive retention, good sharpness (grinding resistance), and excellent grinding wheel life (grinding ratio).

(Effects of the Invention) As is clear from the above, according to the present invention, flat curled fine short metal fibers obtained by grinding the base metal are used as the binding material, so vibration cutting is possible. The process is much simpler and can be produced in large quantities, making it more economical. In addition, the dimensions are mainly in the range of 1 to 20 μm equivalent diameter, which is finer than in the case of chatter vibration cutting, and the shape is not just a straight fiber but a curled shape, that is, a curved or bent flat band shape. Therefore, when mixed and dispersed with abrasive grains, the fine short metal fibers of the above shape intertwine with each other in a complicated manner and form a multilayer network-like extremely fine skeleton that does not easily separate and collapse by contacting each other, and therefore has poor formability. This makes it easy to take out the molded product, transport it, etc. Furthermore, abrasive grains such as diamond are tightly wrapped inside the curved or bent inner side of the fine short metal fibers and are evenly dispersed and held, and the shrinkage rate is large during sintering, so the abrasive grains are held hard and sintered. Therefore, the abrasive grain retention is high and the abrasive grains do not fall off, so the grinding resistance is low and the sharpness can be maintained for a long time.The grinding ratio is also high, so it is easily economical for heavy grinding such as creep feed grinding. can be used.

[Brief explanation of the drawing]

Fig. 1 is an enlarged perspective view showing an example of curled fine metal short fibers used in the present invention, and Fig. 2 shows abrasive particles attached to a multilayer network skeleton formed by curled fine metal short fibers. FIG. 3 is an enlarged perspective view of a mixture in which . (1) Two-curl fine metal short fibers, (2): Abrasive grains. Patent applicant: Shinto Preku Co., Ltd. Representative: Akira Shima Buma
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Claims (1)

[Claims] A sintered abrasive body characterized by being formed and sintered with abrasive grains using flat, curled fine metal short fibers obtained by grinding as a binding material.