JP4645943B2 - Carbide broach made of surface-coated cemented carbide with excellent wear resistance due to lubricated amorphous carbon coating - Google Patents

Description

  The present invention is particularly applicable to the surface of a broach body (hereinafter referred to as a carbide broach body) made of tungsten carbide-based cemented carbide, such as by drawing holes in workpieces such as various Ti alloys, Al alloys, and Cu alloys. The present invention relates to a surface-coated cemented carbide broach (hereinafter referred to as a coated cemented carbide broach) in which a lubricated amorphous carbon-based film deposited on the surface exhibits excellent wear resistance.

In general, a general tool called a broach illustrated in a schematic front view in FIG. 3 is used, and the broach is inserted into a prepared hole made of various Ti alloys, Al alloys, Cu alloys, and the like in a downward direction. A broaching method is known in which a complicated hole having a cross-sectional shape is finished at once by drawing.
In the above broaching method, as shown in FIG. 3, the cutting edge portion formed in the central portion of the broach, which gradually changes from the lower rough blade to the upper finishing blade, cuts the workpiece little by little by the downward movement of the broach. And finished to a predetermined dimension.

As the broach described above, a broach made of a tungsten carbide-based cemented carbide (hereinafter referred to as a cemented carbide broach) is known.
JP 59-205215 A

  In recent years, the performance and output of broaching machines have improved dramatically. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for broaching. Accordingly, broaching has a tendency to further increase in speed. However, in the above conventional carbide broach, when it is used under high-speed machining conditions, the wear progresses rapidly, so that the service life is reached in a relatively short time.

Therefore, the present inventors, from the viewpoint as described above, paying particular attention to the above conventional carbide broach, and as a result of conducting research to improve the wear resistance thereof,
(A) As a cathode electrode (evaporation source) on one side of the vapor deposition apparatus shown in the schematic plan view and schematic front view in FIGS. A sputtering apparatus provided with a Ti target, a sputtering apparatus provided with a WC target as a cathode electrode (evaporation source) on the other side, and a vapor deposition apparatus provided with an electromagnetic coil in each of the sputtering apparatuses were used. The conventional carbide broach (hereinafter referred to as a carbide broach main body) is mounted in a ring shape on a rotary table in the apparatus at a predetermined distance in the radial direction from the central axis of the rotary table. A magnetic field is formed, and the magnetic flux density in the carbide broach body mounting portion in the center of the apparatus is set to 100 to 300 G (Gauss And then, in the state was 300 to 500 ° C. The heating temperature in the apparatus, and as a reaction gas into the apparatus, for example, hydrocarbons, nitrogen and Ar, such as _C 2 _{H 2,} preferably _C 2 _{H 2} flow rate: 25 ˜100 sccm, nitrogen flow rate: 200 to 300 sccm, Ar flow rate: 150 to 250 sccm, and the reaction atmosphere is, for example, a 1 Pa C ₂ H ₂ decomposition gas and a mixed gas of nitrogen and Ar. For example, sputtering power of output: 1 to 3 kW (frequency: 40 kHz) is applied to the cathode electrode (evaporation source) of the WC target of the magnetron sputtering apparatus, and sputtering of output: 3 to 8 kW (frequency: 40 kHz) is applied to the Ti target, for example. When an amorphous carbon-based film is formed on the surface of the cemented carbide broach body under the condition that power is simultaneously applied, this results in formation. The structure of the amorphous carbon-based film thus obtained was observed with a transmission electron microscope (magnification: 2.5 million times). FIG. 1 shows the amorphous carbon-based film of the coated carbide broach 3 according to the present invention. ), A fine particle of a crystalline titanium carbonitride compound having a maximum diameter of 10 nm (nanometer) or less [hereinafter referred to as “crystalline Ti (C, N ) System compound fine particles ”have a distributed structure.

(B) When forming the amorphous carbon-based film of (a), the flow rates of hydrocarbon, nitrogen, and Ar as reaction gases introduced into the vapor deposition apparatus, the WC target of the magnetron sputtering apparatus, and Ti Adjusting the sputtering power applied to the target, the amorphous carbon-based film is measured with an Auger spectroscopic analyzer,
W: 5 to 20 atomic%,
Ti: 5 to 20 atomic%,
Nitrogen: 0.5-18 atomic%,
And the remainder has a composition composed of carbon and inevitable impurities, the resulting amorphous carbon-based film has excellent lubricity due to the carbon-based amorphous body of the substrate, and With the dispersion distribution effect of the crystalline Ti (C, N) -based fine particles in the base made of the carbon-based amorphous body, and the fine graining effect in the magnetic field film formation by the electromagnetic coil, the hardness is remarkably improved, The coating strength is further improved by the inclusion of the W component. Therefore, the coated carbide broach formed by forming this amorphous carbon-based coating (hereinafter referred to as a lubricious amorphous carbon-based coating) is processed at high speed. However, it should exhibit excellent wear resistance over a long period without chipping (small chipping) at the cutting edge.

(C) Prior to the formation of the lubricious amorphous carbon-based coating film of (b) above, the vapor deposition apparatus of (a) above is also used, and both of the magnet coils of the magnetron sputtering apparatus disposed opposite to the vapor deposition apparatus are used. For example, it is applied under conditions of voltage: 50 V and current: 10 A to form a magnetic field with a magnetic flux density of 140 G (Gauss) in the mounting portion of the cemented carbide broach body, and a heating temperature in the vapor deposition apparatus is, for example, 400 ° C. In this state, nitrogen and Ar are introduced as reaction gases at a rate of, for example, nitrogen flow rate: 300 sccm and Ar flow rate: 200 sccm, and a reaction atmosphere consisting of a mixed gas of 1 Pa of nitrogen and Ar, or C ₂ H as the reaction gas. ₂ and nitrogen and Ar, e.g., _C 2 _{H 2} flow rate: 50 sccm, flow rate of nitrogen: 300 sccm, Ar flow rate: introduced at a rate of 230sccm A reaction atmosphere of a mixed gas of decomposition gas and nitrogen and Ar of _C 2 _{H 2} of 1 Pa, the cathode electrode of the Ti target (evaporation source), for example, output: 12 kW (Frequency: 40 kHz) was applied to the sputter power, On the other hand, in the cemented carbide broach body, for example, a glow discharge is generated under a condition where a bias voltage of −100 V is applied, so that either or both of the TiN layer and the TiCN layer are laminated on the surface of the cemented carbide broach body. The TiN layer and the TiCN layer formed as a result of the above are extremely firmly adhered to both the above-described carbide broach body and the lubricious amorphous carbon-based film, and the lubricity is maintained even under high-speed broach processing conditions. Acting as an adhesive bonding layer for preventing the amorphous carbon-based coating from peeling from the surface of the cemented carbide broach body.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results, and on the surface of the carbide broach main body,
(A) In a magnetron sputtering apparatus, a Ti target is used as a cathode electrode (evaporation source), and a film is formed in a magnetic field in a reaction atmosphere composed of a mixed gas of nitrogen and Ar, or a mixed gas of hydrocarbon decomposition gas and nitrogen and Ar. Through a tight junction layer comprising either a TiN layer or a TiCN layer, or a laminate of both, and having an average layer thickness of 0.1 to 3 μm,
(B) Similarly, in a magnetron sputtering apparatus, a WC target and a Ti target are used as a cathode electrode (evaporation source), and a film is formed in a magnetic field in a reaction atmosphere composed of a hydrocarbon decomposition gas and a mixed gas of nitrogen and Ar. Measured with a spectroscopic analyzer,
W: 5 to 20 atomic%,
Ti: 5 to 20 atomic%,
Nitrogen: 0.5-18 atomic%,
And the remainder of the composition is composed of carbon and inevitable impurities, and the crystalline Ti (C, N) compound fine particles are dispersed and distributed on the base of the carbon-based amorphous body by observation with a transmission electron microscope. Demonstrated by depositing a lubricious amorphous carbon-based film with a texture and an average layer thickness of 1 to 3 μm, especially in high-speed broaching, the lubricating amorphous carbon-based film exhibits excellent wear resistance The coated carbide broach is characterized.

Next, in the coated carbide broach of the present invention, the reason why the adhesive bonding layer and the lubricious amorphous carbon-based film constituting the same are limited as described above will be described.
(A) Average layer thickness of tight junction layer The tight junction layer comprising either or both of the TiN layer and TiCN layer is between the carbide broach body and the lubricious amorphous carbon-based coating, and both Tightly bonded and bonded to the cemented carbide broach body is further improved by film formation in a magnetic field. However, if the average layer thickness is less than 0.1 μm, the desired excellent bonded bonding is ensured. On the other hand, if the average layer thickness exceeds 3 μm, it becomes easy to cause thermoplastic deformation particularly in high-speed broaching, which causes chipping in the lubricating amorphous carbon-based film. The layer thickness was determined to be 0.1 to 3 μm.

(B) W content of lubricious amorphous carbon-based coating W component forms the base of the above-mentioned lubricous amorphous carbon-based coating and has the effect of improving the strength of the coating. If it is less than 5 atomic%, the desired high strength cannot be ensured, which causes wear promotion. On the other hand, if its content exceeds 20 atomic%, the lubricity is drastically reduced and chipping occurs at the cutting edge. Since it becomes easy to generate | occur | produce, the content was defined as 5-20 atomic%.

(C) Ti and N contents of lubricating amorphous carbon-based film Ti component, N component, and C (carbon) component are combined under film formation of magnetic field, and crystalline Ti (C, N) is formed in the film. ) It exists as system compound fine particles and has the effect of remarkably improving the hardness of the film and improving the wear resistance, but its content is less than 5 atomic% for Ti component and less than 0.5 atomic% for N component. In this case, the ratio of Ti (C, N) -based fine particles present in the coating is too small, and the desired high hardness cannot be ensured, while the content thereof is 20 atomic% Ti component, and N When the component exceeds 18 atomic%, the strength and lubricity are drastically reduced and chipping occurs at the cutting edge, so the content is Ti: 5 to 20 atomic% and N: 0.5, respectively. It was defined as ˜18 atomic%.

(D) Average layer thickness of lubricating amorphous carbon-based coating If the average layer thickness is less than 1 μm, the desired lubricity and wear resistance effect cannot be ensured, while the average layer thickness exceeds 3 μm. Then, since chipping is likely to occur in the cutting edge portion, the average layer thickness was determined to be 1 to 3 μm.

  The coated carbide broach of the present invention is dispersed in a state where the hardness of the lubricating amorphous carbon-based coating film constituting the same is superfine by magnetic field film formation on the carbon-based amorphous body. Combined with the fact that the crystalline Ti (C, N) -based compound fine particles that are distributed are significantly improved, and the base of the carbon-based amorphous body has high strength due to the action of the W component. In particular, high-speed broaching of workpieces such as various Ti alloys, Al alloys, and Cu alloys exhibits excellent wear resistance over a long period of time without occurrence of chipping.

  Next, the coated carbide broach of the present invention will be specifically described with reference to examples.

As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder all having an average particle diameter of 0.8 to 3 μm are prepared. Blended into the composition shown in Table 1, added with wax, ball milled in acetone for 72 hours, dried under reduced pressure, pressed into various compacts of a predetermined shape at a pressure of 100 MPa. The powder is heated to a predetermined temperature within a range of 1370 to 1470 ° C. at a heating rate of 7 ° C./min in a 6 Pa vacuum atmosphere, held at this temperature for 1 hour, and then sintered under furnace cooling conditions. Then, a round bar sintered body for forming a carbide broach main body having a diameter: 50 mm × length: 1000 mm is formed, and further, from the round bar sintered body, a cutting blade portion maximum diameter: 40 mm × by grinding. Cutting edge length: 600 mm x total length: 80 Carbide broach bodies A-1 to A-10 having a size of 0 mm and a shape shown in FIG. 2 and having rough blades at the cutting edge portion: 25 blades and finishing blades: 25 blades were produced.

Next, each of the above-mentioned carbide broach main bodies A-1 to A-10 is ultrasonically cleaned in acetone and dried, and then the central axis of the main body is placed on the rotary table in the vapor deposition apparatus shown in FIG. Is mounted in a ring shape at a predetermined distance in the radial direction, and the cathode electrode (evaporation source) of the magnetron sputtering apparatus on one side is a Ti target having a purity of 99.9% by mass, the cathode of the magnetron sputtering apparatus on the other side As an electrode (evaporation source), a WC target having a purity of 99.6% by mass is disposed opposite to the rotary table,
(A) First, the inside of the apparatus is evacuated and kept at a vacuum of 0.01 Pa, and the inside of the apparatus is heated to 200 ° C. with a heater, and then Ar gas is introduced into the apparatus and Ar at a pressure of 0.5 Pa is introduced. In this state, a bias voltage of −800 V is applied to the carbide broach body rotating while rotating on the rotary table in this state, and the surface of the carbide broach body is cleaned with Ar gas bombardment for 20 minutes,
(B) Next, the magnetic flux density in the mounting part of the carbide broach body is 140 G by applying the voltage to the electromagnetic coils of both magnetron sputtering apparatuses opposed to the vapor deposition apparatus under the conditions of voltage: 50 V and current: 10 A. In addition to forming a magnetic field (Gauss) and heating temperature in the vapor deposition apparatus at 400 ° C., nitrogen and Ar are introduced as reaction gases at a rate of nitrogen flow rate: 300 sccm, Ar flow rate: 200 sccm, A reaction atmosphere composed of a mixed gas of nitrogen and Ar of 1 Pa, or C ₂ H ₂ , nitrogen and Ar as reaction gases are introduced at a rate of C ₂ H ₂ flow rate: 50 sccm, nitrogen flow rate: 300 sccm, Ar flow rate: 230 sccm. , the reaction atmosphere of a mixed gas of 1Pa of _C 2 decomposed gas of _{H 2} and nitrogen and Ar, cathodic electrodeposition of Ti target (Evaporation source) is applied with a sputter power of 12 kW (frequency: 40 kHz), while the super-hard broach body is subjected to glow discharge under the condition that a bias voltage of −100 V is applied. On the surface of the hard broach body, a tight junction layer composed of either a TiN layer or a TiCN layer having a target layer thickness shown in Tables 3 and 4 or a laminate of both is formed,
(C) Furthermore, assuming that the conditions to be applied to the electromagnetic coil are predetermined values in the range of voltage: 50 to 100 V and current: 10 to 20 A, the magnetic flux density in the mounting portion of the carbide broach body is 100 to 300 G ( The heating temperature in the vapor deposition apparatus is 400 ° C., the bias voltage of the carbide broach body is −100 V, and C ₂ H is used as a reactive gas in the vapor deposition apparatus. ₂ (hydrocarbon), nitrogen, and Ar are introduced at a predetermined flow rate within a range of C ₂ H ₂ flow rate: 25-100 sccm, nitrogen flow rate: 200-300 sccm, Ar flow rate: 150-250 sccm, While using a 1 Pa C ₂ H ₂ decomposition gas and a mixed gas of nitrogen and Ar, the cathode electrode (evaporation source) of the WC target of both the magnetron sputtering devices Is, for example, output: 0.5 to 3.5 kW (frequency: 40 kHz) in a predetermined sputtering power, and the same Ti target has an output: 2.5 to 8.5 kW (frequency: 40 kHz). The coated carbide broaches 1 to 10 of the present invention are formed by vapor-depositing a lubricating amorphous carbon-based film having a target composition and a target layer thickness shown in Tables 2 and 3 under the condition that a predetermined sputtering power is simultaneously applied. And comparative coated carbide broaches 1-12, respectively.
The comparative coated carbide broaches 1 to 12 are formed by forming a lubricating amorphous carbon-based film in which the content of at least one of the constituent components is out of the scope of the present invention.

Next, using the coated carbide broaches 1 to 10 and the comparative coated carbide broaches 1 to 12 of the present invention, the outer diameter: 80 mm × the diameter of the central through hole (center hole): 40 mm × the total length: 40 mm For workpieces with dimensions of
(A) Workpiece material: Ti alloy (JIS TB340PbH) having a composition of Ti-0.15% Pb in mass%,
Drawing speed: 40 m / min.
Number of machining: High-speed drilling of the workpiece center hole under the condition of 5000 pieces (referred to as drawing condition A) (normal drawing speed is 25 m / min.),
(B) Workpiece material: pure Al (JIS A1050),
Drawing speed: 90 m / min.
Number of processing: 15000
High-speed drilling of the center hole of the workpiece under the conditions (drawing condition B) (normal drawing speed is 70 m / min.),
The maximum flank wear width on the rough and finished blades after processing was measured. The measurement results are shown in Tables 2 and 3.

  As a result, the composition of the present invention coated carbide broaches 1 to 10 and comparative coated carbide broaches 1 to 12 of the lubricating amorphous carbon-based film is determined by the Auger spectroscopic analyzer and the layer thickness by the scanning type. When measured using an electron microscope, both showed the same composition and average layer thickness (average value of five cross-sections) as the target composition and target layer thickness, and the structure was measured using a transmission electron microscope. When observed (magnification: 2.5 million times), both the coated carbide broaches 1 to 10 of the present invention and the comparative coated carbide broaches 1 to 10 were formed of crystalline Ti (C, N) on the base of the carbon-based amorphous body. ) A structure in which system compound fine particles are dispersed and distributed is shown.

From the results shown in Tables 2 and 3, the lubricating amorphous carbon-based coating has a structure in which crystalline Ti (C, N) -based compound particles are dispersed and distributed on a carbon-based amorphous body. The invention coated carbide broaches 1 to 10 all exhibit excellent wear resistance even when broaching is performed under high-speed conditions, while the components of the lubricating amorphous carbon-based coating are In the comparative coated carbide broaches 1 to 12 in which the content of at least one of them is out of the present invention, in the high-speed broaching process, when the progress of wear of the lubricious amorphous carbon-based coating is extremely fast, It is clear that chipping may occur in the part, and as a result, the service life is reached in a relatively short time.
As described above, the coated carbide broach of the present invention has excellent wear resistance not only when broaching under normal conditions, but also when broaching various workpieces under high speed conditions. Therefore, it can fully satisfy the labor saving and energy saving of broaching, and further cost reduction.

It is a schematic diagram which shows the result (magnification: 2.5 million times) which carried out the structure | tissue observation of the lubricous amorphous carbon type | system | group film of this invention coated carbide broach 3 using the transmission electron microscope. The vapor deposition apparatus used for forming the adhesion bonding layer of the present invention coated carbide broaches 1 to 10 and the comparative coated carbide broaches 1 to 12 and the lubricating amorphous carbon-based film is shown, (a) is a schematic plan view. (B) is a schematic front view. It is a schematic front view which illustrates a broach.

Claims (1)

On the surface of the broach body made of tungsten carbide base cemented carbide,
(A) In a magnetron sputtering apparatus, a Ti target is used as a cathode electrode (evaporation source), and a film is formed in a magnetic field in a reaction atmosphere composed of a mixed gas of nitrogen and Ar, or a mixed gas of hydrocarbon decomposition gas and nitrogen and Ar. Through a tight junction layer consisting of a laminate of either or both of a titanium nitride layer and a titanium carbonitride layer and having an average layer thickness of 0.1 to 3 μm,
(B) In a magnetron sputtering apparatus, a tungsten carbide target and a Ti target are used as a cathode electrode (evaporation source), and a film is formed in a magnetic field in a reaction atmosphere composed of a hydrocarbon decomposition gas and a mixed gas of nitrogen and Ar. Measured with a spectroscopic analyzer,
W: 5 to 20 atomic%,
Ti: 5 to 20 atomic%,
Nitrogen: 0.5-18 atomic%,
And the balance is composed of carbon and inevitable impurities, and a structure in which fine particles of crystalline titanium carbonitride compound are dispersed and distributed on the base of the carbon-based amorphous body by observation with a transmission electron microscope. Made of a surface-coated cemented carbide alloy that exhibits excellent wear resistance, and has a lubricious amorphous carbon-based coating formed by vapor deposition of a lubricating amorphous carbon-based coating having an average layer thickness of 1 to 3 μm brooch.

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