MANUFACTURING METHOD THEREOF

Technical Field The present invention relates to a ceramic/carbide socket cutting insert with high toughness and the manufacturing method thereof, which is used in lathe and milling machines, wherein its cutting parts are made of ceramic or carbide, its body is made of steel material and/or metallic intermediate layer used to unite two materials in between.

The present invention particularly relates to a socket cutting insert that performs the machining process over all kinds of metallic, wood, polymeric material by being fixed to tool holders using in the lathe or milling machines.

State of the Art

The process of giving a cylindrical or rotational shape to the part by machining over a workpiece that makes a rotational movement is called turning. In the turning process, the machining process is carried out with the rotation of workpiece and the proceeding movement of tool. The proceeding movement of tool can be along the axis of the workpiece, on the other hand, this means that the diameter of the part will be reduced to a smaller size. The cutting tools to be used in the turning process are instruments forging an industrial product by being fixed to a machine tool. This shaping process usually are carried out by machining on the material. Cutting tools, which are used for manufacturing various machine and machine parts, must meet high stresses arising from the machining process. Cutting tool equipment are classified based on their inner structure, lifetime, type of manufacturing, mechanical and physical properties. Carbon steels and tool steels, high-speed steels, carbide-tipped cutting tools, ceramics and diamonds can be given as an example of this classification.

In the machining process, either continuous cutting treatment with single-point tools as in turning and drilling process, or non-continuous cutting treatment with multipoint tools as in milling process is carried out. During the continuous cutting treatment, high temperatures occur on the cutting insert, while major changes of strength and temperature appear during the non-continuous cutting treatment since the cutting inserts are subjected to impact loads. To minimize these negativities, appropriate rotation and cutting speeds should be given according to the desired surface quality and the internal structure of the material. The tool must have sufficient impact resistance to overcome the heating and chilling effect, which also occurs in the continuous rotation cycle. If this impact resistance of the cutting tool is low, the tool insert is broken quickly.

Considering all of these problems, cutting tools must have some features. Cutting tools must be resistant against flank wear and deformation, must have toughness against breakage, should not constitute a chemical reaction with the workpiece material, must be chemically balanced against oxidation and diffusion, should have high resistance to sudden thermal changes and must be low-cost.

However, due to both cost and production difficulties, it is very difficult to find a cutter with all these features. Because these features may conflict with each other. The development of technology has necessitated to develop different cutting tools. Eventually, in order to have higher toughness, to have better wear resistance, to have higher temperature resistance, carbide tool materials have been developed.

Carbide cutting inserts are temperature-resistant tool materials and are produced by sintering of hard carbide powders with cobalt or nickel. These materials were firstly developed since the usage of diamonds were expensive and for the purpose of producing sufficient wear-resisting mold material. However, it was observed that it was a rough structure with many faults and was not found satisfactory as a cutting tool and mold material. With the advancing technology, it was pressed by mixing thin tungsten carbide powders with a small amount of iron, nickel or cobalt powders through the powder metallurgy technique. It was then sintered at about 1300-1500°C temperature. From that time, WC-Co-based cutting tools have been manufactured in different types for different materials and cutting operations. Approximately 50% of carbide production is used in the machining process. These materials are also called“sintered carbide”. Since they exhibit a good wear resistance, they can be used effectively at cutting speeds from 40 m/min to 350 m/min without losing its hardness and sharpness.

Carbide-based cutting inserts exhibit a high performance up to 800°C. However, the hardness decreases with the higher temperature increases. Considering the resistance to high temperatures, ceramics perform much better performances. Because these cutters can maintain their hardness up to about 1200°C. However, since ceramic cutters are harder and therefore have more fragile structures than other cutters, these cutters are preferred in the final finishing passes of the hard metals where there is a continuous machining process.

The cutting inserts used in the present art are produced by the powder metallurgy method after being pressed into the powdered tungsten carbide material mold and then being sintered; and used by being attached to a tool chuck in a mount-demount manner. Tungsten carbide cutting inserts are used for machining of difficult-to-machine materials and cast irons, except for iron. Both the cutting parts and the body of these cutters are manufactured in a single piece from a single material (WC-Co) through the powder metallurgy.

The patent application in the state of art numbered US7153562B2 relates to, in general, the coated cemented carbide cutting tool with a cutting insert for processing steel in applications with high requirements on wear resistance and toughness behavior of shear edge. The tool is particularly suitable for turning stainless steels. The patent document in the prior art numbered EP1 103635A2, on the other hand; relates to a coated ceramic- carbide insert (cutting tool) which is particularly useful for wet and dry machining of low and medium-alloy steels and stainless steels. Another patent application numbered US6000312A relates to a coated ceramic-carbide cutting insert. The ceramic-carbide cutting insert is tungsten carbide-based and has a surface zone with enriched cobalt binder phase.

The cutting edges of these cutting inserts in the present art are easily worn and when worn, the entire socket is disposed as a single piece. For single-piece cutting inserts, they are disposed when the cutting parts are worn 0,2-0, 3 mm. In other words, although the cutting inserts produced in the present art are not resistant to breakage and abrasion; since they are rigid and have a high temperature of melting, their recycling is quite difficult.

Since the socket cutting inserts used in the state of art are generally produced in a single piece from ceramic/carbide material, their impact absorption capabilities are also low because they are rigid and have a low toughness. These inserts are easily broken under light impacts and vibration problems occur during the machining process. The resulting vibration affects the surface roughness in the same time.

B Cost of the socket cutting inserts used in the state of art increases due to the expensive carbide material and since they are produced by pressing with the powder metallurgy, the design limitations occur due to the failure to produce the desired geometry.

The invention relates to a ceramic/carbine socket insert, wherein it overcomes the disadvantages in the state of art, has a higher toughness, is more resistant and the less carbide/ceramic material are used, and therefore it is low-cost.

Brief Description and Objects of the Invention

In the present invention, it is disclosed a ceramic/carbide socket cutting insert with high toughness. One of the important objects of the invention is that the ceramic/carbide socket cutting insert with high-toughness is resistant to impacts since its toughness would be higher than single piece ceramic and carbide cutters by the usage of steel in its body section. The socket cutting insert, thus, becomes resistant to instantaneous breakages and its life span extends. Another object of the invention is to reduce the usage of ceramic or carbide material that is expensive due to the fact that the cutting part of the insert belonging to the socket cutter having a high-toughness is ceramic/carbide and its body is steel.

One of the objects of the invention is to manufacture a socket cutting insert that is resistant to impacts. Another object of the invention is to manufacture a long-lasting socket cutting insert and to prevent the dispose of the material.

Because the body of the inventive socket insert is steel, the cost decreases as the ceramic/carbide material will be used less.

Another object of the invention is to manufacture socket cutter with high-toughness by powder injection molding method. Thus, by means of powder injection molding method, since any shape can be given by this kind of molding, design limitations are eliminated, grinding and sharpening durations and labor processes are reduced. Another object of the invention is to make the mass production rate quite high and easy by means of manufacturing the socket insert by using a multi-span mold.

Brief Description of the Figures Disclosing the Invention

In order to structure the present invention and understand its advantages with additional elements in the best manner, it should be evaluated together with the figures explained below.

Figure 1 : Flow chart of the manufacturing method of the inventive ceramic/carbide socket cutting insert with high-toughness.

Figure 2: The inventive ceramic/carbide socket cutting insert with high-toughness. Description of the Elements/Components/Parts Forming the Invention

In order to better explain the ceramic/carbide socket cutting insert with high-toughness developed by this invention, the parts and components in the figures are numbered, and the equivalent of each number is given below:

10. Socket cutting insert 11. Cutting part

12. Body

20. Carbide feedstock

21. Carbide powder

22. Binder 30. Injection Machine

31. Mixer

32. Injection Bench 40. Insert

50. Solvent

5

SUBSTITUTE SHEETS (RULE 26) 60. Sintering Furnace

Description of the Invention

The inventive ceramic/carbide socket cutting insert with high-toughness (10) used in the lathe and milling machines enables to perform the machining process over all kinds of metallic, wood, polymeric material by being fixed to tool holder or tool chuck in the lathe and milling machines.

The socket cutting insert (10) with high-toughness consists essentially of tungsten carbide-cobalt alloy cutting parts (11 ), a body made of steel (12) and a metallic intermediate layer used for joining cutting parts (1 1 ) and body (12) materials. Steel body (12) is placed in the mold after being coated with metallic intermediate layer material and ceramic or carbide feedstock is injected into only its cutting parts (1 1 ) by means of the powder injection molding method, and afterwards, binder removal and sintering, which are the processes of powder injection molding, are performed, thus, ceramic/carbide socket cutting inserts (10) with high-toughness are produced. In the invention, ceramic-carbide tungsten used in the cutting part (1 1 ) is carbide-cobalt mixture.

In order to obtain the inventive socket cutting insert (10), in general, carbide feedstock (20), injection machine (30), insert (40), solvent (50), and sintering furnace (60) is used.

The carbide feedstock (20) is achieved by the mixture of carbide powder (21 ) and binder (22). The injection machine (30) consists essentially of a mixer (31 ) that enables the mixture of carbide powder (21 ) and binder (22) and the injection bench (32) that enables to inject the feedstock (20) obtained from the mixture to the insert (40).

The corners of the insert (40) has a hollow structure. Carbide feedstock (20) is injected into these hollow structures and thus the cutting part (1 1 ) is gained. The solvent (50) takes some components within the carbide feedstock (20) on the corners of insert (40). The sintering furnace (60) enables the vaporization of binder (22) inside the ceramic/carbide feedstock (20) and the sintering of ceramic/carbide feedstock (20).

The inventive socket cutting insert (10) is manufactured through the powder injection molding method. Some process steps are applied for the socket cutting insert manufacturing method. First, the carbide (WC-Co) powders (21 ) are placed into the mixer (31 ) for being mixed with the binder (22). The mixture mixed in the mixer (31 ) becomes injectable into the mold on the injection bench (32). The carbide feedstock (20), which is ready for injection, is injected into the corners of the steel insert (40) by means of the injection machine (30). For the injection process, the insert (40) with the hollow corners is placed into the injection machine (30) and ceramic/carbide feedstock (20) is injected into these hollows. Following the injection process, the insert (40) with ceramic/carbide feedstock (20) in its corners is rested in the solvent (50). By means of this resting process, some components in the feedstock (20) is taken. The insert (40) with the feedstock (20), whose components are taken, is sintered in the sintering furnace (60) under favorable conditions. At the end of the sintering process, the binder (22) vaporizes and sintered ceramic/carbide is gained. At the end of the sintering process, metallic cobalt (Co) powders are spread well among the tungsten carbide powders (WC) and form a rigid structure. The resulting rigid structure generates a socket cutting insert (10) with a steel body (12), having cutting part (1 1 ) with rigid-structured corners. The inventive socket cutting insert (10) can be manufactured in the geometries specified in the ISO tool codification system (S, T, C, D, W, R, A, B, etc.). The geometry of said socket cutting insert (10) may be triangular, rectangular or polygonal, besides, it may also have a trapezoidal geometry depending on the usage area. In addition to all these, again according to the usage area, the geometry of the said socket cutting insert (10) may also be circular. If the socket cutting insert (10) has a triangular, rectangular, polygonal or trapezoidal geometry, at least one cutting part (11 ) or cutting parts (11 ) are located on at least one corner or edge of the socket insert (10). Flowever, if the socket cutting insert (10) has a circular geometry, the cutting part (1 1 ) is located on anywhere or entire of the outer wall of the circle. The inventive socket cutting insert (10) is used for performing the machining process over all kinds of metallic, wood, polymeric materials.