Rotary tool and its cutting part

Abstract

A rotary tool (T) has a rotary segment (10) with an opposed surface opposed to a work surface and a plurality of cutting parts (20) arranged on the opposed surface. Some cutting parts (20) include tips (22a) made of a grinding tool segment obtained by binding abrasive grains by a metal binder and the other cutting parts (20) include tips (24a) made of a sintered material harder than the grinding tool segment, and the respective cutting parts (20) are arranged such that the tips (24a) are located at positions more outward than the tips (22a) with respect to radial directions of the rotary segment.

Description

TECHNICAL FIELD [0001] The present invention relates to a rotary tool and a cutting part thereof for working outer surfaces of walls and floors of buildings, ships, bridges and the like to remove paints, adhesives and the like adhered to the outer surfaces. BACKGROUND ART [0002] A rotary grinder in which a plurality of grinding tool segments are arranged at the outer periphery of a saucer-shaped rotary segment is known as a tool for working surfaces such as floor surfaces and wall surfaces of various structures. The respective grinding tool segments used to form this grinder are obtained by sintering, for example, a mixture of a certain amount of diamond abrasive grains and a metal binder. A work surface can be abraded by bringing the respective grinding tool segments provided on the grinder into contact with the work surface while rotating the entire grinder at high speed. [0003] However, in the case of using the above grinder to remove old films adhered, for example, to floor surf...

AI Technical Summary

Benefits of technology

[0009] In this cutting part, the radially outer part of the tip, i.e. a part thereof performing more cutting work due to its higher peripheral speed, is made of the hard sintered material having a sharp cutting quality. Thus, the surface portion of the work surface can be lightly removed at high speed by this part, thereby preventing an occurrence of heat adhesion. On the other hand, the radially inner part of the tip, i.e. a part thereof performing less cutting work due to its lower peripheral speed, is made of the grinding tool segment (grinding tool segment obtained by binding the abrasive grains by the metal binder) having a relatively dull cutting quality due to its lower hardness than the sintered material. This can prevent the entire tip from cutting in excessively deep.

[0010] Further, by making the radially outer part of the tip performing more cutting work of the sintered material while making the radially inner part thereof performing less cutting work of the grinding tool segment, the wear speed of the tip can be made uniform over the entire radial direction. Thus, unlike the prior technology cutting part whose tool segment is entirely made of the same material, wear of the radially outer part of the tool segment prior to the radially inner part thereof can be prevented from occurring. As a result, the entire tool life can be extended.

[0012] For example, cemented carbide, ceramic, cermet and the like may be used as the hard sintered material. However, a polycrystalline diamond sintered material (PCD) and a polycrystalline cubic boron nitride sintered material (PCBN) are particularly preferable (claim 2). By using such a particularly hard sintered material, adhesion can be more securely prevented from occurring and a longer tool life can be given.

[0021] With this rotary tool, while the tips made of the hard sintered material and having a sharp cutting quality lightly remove the surface portion of the work surface at high speed to prevent an occurrence of heat adhesion, the presence of the tips made of the grinding tool segment having a lower hardness than the sintered material and a relatively dull cutting quality suppresses deep cutting-in of the tips. Further, the removing work by the tips made of the hard sintered material is assisted by the tips made of the grinding tool segment. If the work surface is scratched by the removing work by the tips made of the sintered material, such scratches can be ground off or finished by the tips made of the grinding tool segment.

[0023] Further, if the rotary tool comprises at least first cutting parts having tips made of the sintered material and second cutting parts having tips made of the grinding tool segment, and the second cutting parts are arranged such that the tips thereof are located at positions more inward than the tips of the first cutting parts made of the sintered material with respect to the radial directions of the rotary segment (claim 10), both the backing preventing effect and the excessive cutting-in preventing effect can be enjoyed.

Problems solved by technology

On the other hand, the radially inner part of the tip, i.e. a part thereof performing less cutting work due to its lower peripheral speed, is made of the grinding tool segment (grinding tool segment obtained by binding the abrasive grains by the metal binder) having a relatively dull cutting quality due to its lower hardness than the sintered material.

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