JPS61136747A - Surface treatment of cutting-tool holding part - Google Patents

Abstract

PURPOSE:To obtain a uniform thickness of a covered layer in the part far from an equal distance by carrying-out evaporation-deposition treatment in the state where the evaporation center of the metal such as titanium as evaporated substance and the center line of a treated article, i.e., the main shaft are allowed to coincide with each other. CONSTITUTION:Inside a vacuum container 10, glow electric discharge (plasma) is generated between an evaporation container 12 on a positive-electrode side and a holding tool 16 on a negative-electrode side thermion beams 15 vaporize titanium. Titanium atoms after evaporation are inonized together with nitrogen 11 during the passing through the glow electric-discharge region. Then, the atoms are accelerated by the negative voltage of the main shaft 1 on the negative electrode side, and collide with the main shaft 1 as treated article by the high kinetic energy, and evaporation-deposited as titanium nitride onto the surface of the main shaft 1. At this time, the treated article simultaneously collides with argon ions, and sputter etching state is formed, and an avaporation- deposited film, i.e., covered layer is formed with a strong adhesion force onto the surface of the treated article, in particular on a tapered hole 4 in purification.

Description

Detailed Description of the Invention Technical Field of the Invention The present invention is directed to forming a wear-resistant and corrosion-resistant cemented carbide metal compound coating aWg on the surface of the main spindle of a machine tool and the tool holding part of a tool holder by ion plating. Regarding the method.

Prior Art The main spindle of a conventional machine tool is made of special steel, a tapered hole is machined at its tip, the surface is hardened and tempered, and the outer and inner diameters are finished by grinding. When a tool holder holding an end mill or the like is attached to the taper hole of this spindle and cutting is performed, frenoting (fine movement) wear and red rust due to oxidation occur on the conical surface of the tool holder or the holding surface of the spindle. Occur. When a machine tool is used for a long period of time, the fretting wear progresses and the shape of the fitting portion between the spindle and the tool holder deteriorates, resulting in a decrease in machining accuracy during cutting.

Such a fretting phenomenon can be prevented to some extent by forming a coating layer of a hard metal compound on the surface 1 to impart wear resistance and corrosion resistance to the surface.

However, when forming such a hard metal compound coating layer, high-temperature heat is applied to the tool holder and spindle, resulting in thermal deformation of the material of the tool holder and spindle, which causes damage to the parts. On the contrary, this causes a decrease in machining accuracy.

For example, in a forming method using plasma spraying, the sprayed metal is heated to its melting point, so that the metal layer on the surface of the tool holder or spindle is tempered.

In addition, with this plasma spraying method, it is difficult to form a uniform coating layer with an appropriate thickness, so after forming a deposited layer of 50 μm or more, grinding work is required to reduce the film thickness to 1 to 10 μm again. In addition, mechanical etching of the surface of the tool holder or spindle is required before deposition.

On the other hand, according to the inventor's experiments, the fretting phenomenon described above tends to occur locally on the open end side of the taper hole of the spindle and the corresponding outer peripheral surface of the tool holder. The reason for this is presumed to be that the rigidity at the open end side of the spindle is relatively low, and a gap is formed at the open end side of the spindle when the tool holder is attached.

That is, as shown in FIG. 1, when the tool holder 2 is attached to the spindle I, the open end of the spindle 1 is fixed by the acting force F, which is the sum of the holding force in the axial direction and the fluctuating load in the axial direction during cutting. At the side, the main shaft 1 is deformed in the direction of radial expansion, and as a result, a gap is formed at that part. Therefore, when a vibration load in the tangential direction is applied between the spindle 1 and the tool holder 2 due to minute vibrations during cutting, a stuck area will appear on the contact surface between the spindle 1 and the tool holder 2, as shown in Figure 2. A and a slip area B occur. This slip area B is a part where the contact pressure between the spindle 1 and the tool holder 2 is low, and the rough surface causes relative soaking, which is the main cause of the flexo-ch phenomenon.

Therefore, the fretting phenomenon can be effectively prevented by preventing the generation of gaps in this sliding region B and increasing the wear resistance and corrosion resistance of the relative sliding portion.

OBJECT OF THE INVENTION The object of the present invention is to use titanium nitride or titanium carbide as metals, and chromium, silicon, and zirconium, which are effective in preventing fresotting without causing thermal deformation to the surface of the spindle or tool holder. , forming a hafnium nitride or carbide (hereinafter referred to as titanium compound, etc.) coating layer.

SUMMARY OF THE INVENTION Therefore, the present invention utilizes a physical vapor deposition process, that is, an ion plating process, to coat the holding surface of the main shaft of a machine tool, the conical surface of a tool holder, or both of the holding surface and the conical surface of the tool holder, thereby forming a metallic compound. In other words, a coating film made of a titanium compound or the like is formed thickly on the open end side of the spindle, thereby imparting wear resistance and corrosion resistance to areas where fretting is likely to occur, thereby effectively preventing fretting. . In this ion plating process, the temperature of the workpiece is below the high-speed steel tempering temperature, for example 500°C.
Since the material can be vapor-deposited in the following manner, thermal deformation of the material does not occur even after the processing, and therefore processing accuracy is improved.

Configuration of Processing Target The configuration of the processing target will be specifically explained below based on the drawings.

First, Fig. 3 shows the main shaft 1, and Fig. 4 shows the main shaft 1.
A tool holder 2 is shown. The tool holder 2 is
The cutting tool 3 is held at the tip.

When this cutting tool 3 is installed in the tapered hole 4 of the main spindle 1 and receives rotation of the main spindle 1 from the key 9 to cut the workpiece, the holding surface 5 of the tapered hole 4 of the main spindle 1 and the tool holder An alternating load of minute vibrations is generated between the conical surface 6 of No. 2 and the conical surface 6 of No. 2. As a result, as described above, a sticking region A and a slipping region B are generated on the contact surface between the conical holding surface 5 and the conical surface 6, and the portion of the slipping region B, that is, the taper of the main shaft 1, is generated. A fretting phenomenon occurs on the open end side of the hole 4, and red rust occurs due to the resulting oxidation phenomenon.

Therefore, the present invention, as shown in FIGS. 3 and 4,
At the stage of pre-machining, the apex angle θ1 of the cone of the holding surface 5 as a tool holder is set to be larger than the final apex angle θ, and the apex angle θ2 of the conical surface 6 as a tool holder is set to be larger than the final apex angle θ. When the tool holder 2 is installed in the taper hole 4 of the spindle 1, a large gap is formed on the open end side of the spindle 1 by setting the titanium compound coating layer 7 to be smaller than 7. 8 is formed on the holding surface 5 and the conical surface 6.

Therefore, the titanium compound coating layer 7.8 is thicker on the open end side of the spindle 1, in other words, it is thicker on the tapered bottom portion of the tool holder 2, that is, in the sliding region B. In this way, the surface in areas where flefting is likely to occur is strengthened by the coating layer 7.8 made of a titanium compound or the like.

Surface Treatment Method of the Present Invention Next, FIG. 5 shows the surface treatment method of the present invention using ion plating treatment.

Nitrogen 11 is fed into the vacuum container 10 .

Titanium 13 as a vapor deposition material is placed inside the evaporation container 12 on the anode side. On the other hand, a thermionic beam 15 is emitted toward the titanium 13 by the cathode gun 14 .

Then, hold the holder 16 on the cathode side as an object to be treated, for example, with the main axis 1 facing downward with the taper hole 4 and with the axis aligned with the center line of the evaporation container 10, that is, the evaporation center of the titanium 13. is held in A high voltage is applied between this holder 16 and the evaporation container 12 by a power source 17. Note that a power source 18 is separately connected to the cathode gun 14.

A glow discharge (plasma) is generated inside the vacuum container 10 between the evaporation container 12 on the anode side and the holder 16 on the cathode side, and the thermionic electron beam 15 evaporates the titanium 13. The atoms of titanium 13 after evaporation are ionized together with nitrogen 11 while passing through this glow discharge region, are accelerated by the negative voltage of the main axis 1 on the cathode side, and collide with the main axis l as the object to be processed with high kinetic energy. Then, titanium nitride is deposited on the surface. At this time, the object to be processed is simultaneously bombarded with argon ions and enters a state of sputter etching, so that a vapor deposited film, that is, a coating layer 7, is formed on the surface of the object with strong adhesion while being cleaned in the taper hole 4. Ru.

In particular, since the vapor deposition container 12 and the main shaft 1 as the object to be processed are located on the same axis, and the opening end side of the holding surface 5 is located closest to the titanium 13 of the vapor deposition material,
The thickness of the deposited layer is thick at that part, and gradually becomes thinner as it moves away from the area. As a result, the coating layer 7 has 1 to
It is formed to a thickness in the range of 10 μm to fill the gap. Since such an ion plating process is a so-called low-temperature process, the object to be processed does not undergo thermal deformation or strain after the process, and is therefore thermally stabilized.

Note that similar processing is performed for the tool holder 2 as well.

Moreover, such a coating layer 7.8 is sufficiently effective if it is formed only on one of the spindle 1 and the tool holder 2.

Effect of the invention The present invention provides the following effects.

First, since the ion plating process can be performed at a low processing temperature, no thermal deformation or thermal stress strain remains on the spindle or tool holder after the process, and thermal deformation can be minimized.

In addition, in this ion plating process, the kinetic energy of the vapor deposition material is higher than that of other vapor deposition methods, so
Stable hard coating with excellent wear and corrosion resistance! , a layer can be formed after strong bonding force.

In particular, since the evaporation process is performed with the evaporation center of the metal such as titanium as the evaporation substance and the center line of the workpiece, ie, the main axis or tool holder, the coating layer has a uniform thickness at the same distance. Furthermore, a thick film is formed at the part closest to the deposited material, that is, a part where fretting is likely to occur, and becomes thinner inversely as the distance increases. The sliding part due to vibration is further strengthened.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view showing the fitting surface between the conventional spindle and tool holder, Fig. 2 is an enlarged sectional view showing the fitting surface between the main spindle and the tool holder, and Fig. 3 is the process of the present invention. FIG. 4 is a partially broken side sectional view of a tool holder also according to the processing method of the present invention, and FIG. 5 is a schematic sectional view of an apparatus for ion plating processing. ■・・Spindle, 2・・Tool holder 3・・Cutting tool, 4・・
・Tapered hole, 5... Holding surface, 6... Conical surface, 7.8...
Layer 5.

Claims (1)

[Claims] A titanium compound is applied to the surface of the cutting tool holder of the workpiece by ion plating, with the axis of the main shaft or tool holder as the workpiece aligned with the evaporation center of titanium, etc. as the vapor deposition material, in a vacuum. A method for surface treatment of a cutting tool holder, characterized by depositing a metal coating layer such as .