JP2006159339A - Cutting method for steel and cutting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method for steel and its device capable of improving machinability of free-cutting steel and extending tool life even in cutting the free-cutting steel at high speed. <P>SOLUTION: In the cutting method for steel, the workpiece is cut with the cutting tool 30 while the workpiece 10 mounted on a device body 60 is being rotated. The workpiece 10 is the free-cutting steel containing at least B, N, and Al, and a section between the device body 60 and the cutting tool 30 is kept to be an electrically insulating state, and cutting work is performed by applying a predetermined current to the section in between the cutting tool 30 and the free-cutting steel 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steel cutting method and a cutting apparatus for cutting a work material using a cutting tool, and more particularly to a steel cutting method capable of reducing wear during cutting and extending the life of the tool, and the cutting method thereof. The present invention relates to a cutting device.

  Conventionally, as a cutting device for cutting steel as a work material, a cutting device 50 as shown in FIG. 6 is exemplified. The cutting apparatus 50 includes a grounded apparatus main body 60, a rotating chuck 61, and the like. The chuck 61 is configured to be able to attach the work material 100. The work material 100 is rotated by rotating the chuck 61 by a motor (not shown) disposed in the apparatus main body 60 and is pressed by pressing the cutting tool 30 attached to one end of the apparatus main body 60. It has come to be.

  For example, as an example of such an apparatus configuration, the cast iron (work material) attached to the apparatus main body is electrically insulated from the apparatus main body, and a predetermined current is passed between the cutting tool and the cast iron while A cutting device for cutting cast iron using a cutting tool has been proposed as an experimental device (see Non-Patent Document 1).

H. S. Shan, P.A. C. Pandey. Thermoelectric compensation in metal cutting, Microtechnic, 1970, 24, 1, 30-32.

  By the way, when cutting the work material 100 using the cutting apparatus 50 as shown in FIG. 6, the cutting tool 30 and the work material 100 are dissimilar metals, and both are in a high temperature contact state during cutting. Therefore, a voltage depending on the Zeibeck coefficient is generated between the two. As a result of this voltage generation, as shown by the broken line in FIG. 6, a current flows with the tool 30-the work material 100-the device main body 60 as an electrical closed circuit, and the current in this circuit is an electrical resistance (mainly a device). It depends on the resistance of the main body 60 and flows very little (less than about 1 mA). The current that flows due to the Zeibeck effect varies depending on the electrical resistance, cutting conditions, and the like of the cutting device 50, which shortens the tool life and causes variations in the tool life.

  In addition, as described in Non-Patent Document 1, it has been experimentally attempted to actively flow an electric current between a cutting tool and a work material that is steel. However, no results have been obtained that the machinability is improved and the tool life is prolonged.

  On the other hand, when cutting steel, which is a work material, using a cutting tool such as a bite, conventionally, an internal inclusion of the steel material as the work material is used to improve the machinability of the work material. As a result, various free-cutting steels have been developed and put to practical use. In particular, such free-cutting steel is used for many parts that require cutting among automobile parts.

  However, the free-cutting steel developed as described above is intended for machinability and long tool life. However, emphasis is placed on the control of the internal inclusions and the structure of the steel material as the work material. Oita development, the machinability (machinability) of the free-cutting steel and the wear resistance of the cutting tool are combined with the material of the steel (internal inclusions and its structure) and the actual cutting method. In other words, it was not developed by associating the material of free-cutting steel with the cutting state of free-cutting steel at the time of cutting.

  Further, as one of the free-cutting steels, B, N and Al elements are included, and during cutting, N and Al contained in the free-cutting steel react to form a coating made of AlN on the surface of the cutting tool. Free-cutting steel (for example, BN free-cutting steel manufactured by NKK Steel Co., Ltd.) that forms a film and improves the tool life has been developed.

  However, in order to further improve the machinability and wear resistance of the cutting tool, the free-cutting steel is also required to improve the cutting method and improve the productivity of the machined product. That is a major issue in the future.

  The present invention has been made in view of such problems. The object of the present invention is to provide a free-cutting steel even if a free-cutting steel containing at least B, N and Al is cut at a high cutting speed. An object of the present invention is to provide a steel cutting method and a cutting apparatus capable of improving the machinability of the steel and extending the life of the cutting tool.

  The present inventors have conducted many experiments and studies to solve the above-mentioned problems. As a result, when a specific type of free-cutting steel is cut, a protective film called verak is formed on the surface (cutting surface) of the cutting tool due to the elements contained in the free-cutting steel, and stably. In order to form the protective film, it is necessary to cut a current of a specific magnitude between the cutting tool and the free-cutting steel as a work material, and this stable protective film is formed. As a result, it was found that wear of the cutting tool was suppressed, the thickness of the chips during cutting was reduced, and the cutting resistance was reduced.

  The present invention is based on the above-mentioned new knowledge obtained by the present inventors, and the steel cutting method according to the present invention rotates a work material attached to the apparatus main body and cuts it with a cutting tool. A steel cutting method, wherein the cutting material is free-cutting steel containing at least B, N, and Al, and the cutting tool and the free tool are electrically insulated between the apparatus main body and the cutting tool. It is characterized by cutting by passing a current of a predetermined value between the cutting steel.

  In the present invention, the free-cutting steel containing at least B, N, and Al is a metal material containing Fe as a main material, hexaboron nitride, and a simple substance of Al. In addition, it is a material capable of forming a protective film made of AlN. Then, electrical insulation is performed between the apparatus main body and the cutting tool so that an electric current in which the work material, the apparatus main body, and the cutting tool are electrically closed circuit, that is, unstable current due to the Zeibeck effect does not flow. Is. As described above, when the free cutting steel is cut with the cutting tool while a predetermined current is passed between the cutting tool and the free cutting steel in an electrically insulated state between the apparatus main body and the cutting tool, the tool life is extended. The machinability of free-cutting steel is also improved.

  As a preferred embodiment, the steel cutting method of the present invention is characterized in that the current is allowed to flow in a range of 5 mA to 10 mA, and by performing a cutting while flowing a minute current in such a range, The machinability (machinability) of the work material is further improved, and the wear of the tool is further reduced. That is, when this current value is smaller than 5 mA, flank wear is suppressed, but rake wear cannot be effectively suppressed. Further, when the current value is larger than 10 mA, the wear of the flank proceeds and the tool life is reduced.

  As a preferred embodiment, the steel cutting method is characterized in that the cutting speed at the time of cutting is in the range of 100 m / min to 300 m / min. When cutting is performed based on the above conditions, a protective film of AlN is efficiently formed on the surface (cutting surface) on which the cutting tool is worn. That is, when the cutting speed is lower than 100 m / min, the protective film of AlN cannot be efficiently formed on the cutting surface of the cutting tool. Similarly, when it is higher than 300 m / min, the protective film of AlN cannot be efficiently formed on the cutting surface of the cutting tool.

  As a device capable of effectively carrying out the cutting method, a steel cutting device according to the present invention includes a power source for generating the current and a current adjusting means for adjusting a current flowing from the power source. Yes. As a more preferable aspect, the steel cutting device according to the present invention further includes a cutting tool mounting body that is electrically insulated from the device main body. By using the cutting tool mounting body as described above, the cutting tool can be attached to the apparatus main body, and the apparatus main body and the cutting tool can be electrically insulated.

  Furthermore, as a device capable of effectively carrying out the steel cutting method, the steel cutting device according to the present invention is a steel cutting device in which a work material attached to the device main body is rotated and cut with a cutting tool. The cutting device includes an electrical insulator disposed between the device main body and the cutting tool, a power source for generating a current, and adjusting the current from the power source to adjust the cutting tool and the workpiece. Current adjusting means for passing a current between the cutting material, and the current adjusting means forms a protective film on the cutting surface of the cutting tool by an element contained in the work material during cutting. It is characterized in that a current of a predetermined value that is optimum for the current flows.

  When cutting with the steel cutting apparatus of the present invention, a free cutting steel as shown above is used as a work material to form a protective film on the cutting tool during cutting. Attach to. And in this attachment, an electrical insulator is arrange | positioned between an apparatus main body and a cutting tool so that the electric current which made the work material, the apparatus main body, and the cutting tool the electrical closed circuit may not flow. As a result, unstable current does not flow between the work material and the cutting tool, so that wear of the cutting tool during cutting is suppressed.

  Furthermore, in this electrical insulation state, at the time of cutting, the cutting surface of the tool (specifically, the cutting tool, and by cutting while passing a current adjusted to a predetermined value between the work material and the cutting tool, Since the protective film is formed on the flank and rake face of the tool that wears in contact with the work material, wear of the rake face and flank face is suppressed, and the machinability of the tool is also improved.

  According to the steel cutting method and the cutting apparatus according to the present invention, in cutting of a specific work material that can form a protective film on the cutting tool during cutting, a slight current is passed between the cutting tool and the work material. While cutting, the protective film is surely formed on the cutting surface of the cutting tool, so that wear of the rake face and flank face of the cutting tool can be suppressed, and the tool life can be extended. Further, the cutting resistance is reduced, the thickness of the chips is reduced, and the machinability of free-cutting steel is improved. And since the said effect is acquired with a slight electric current, cutting can be implemented cheaply.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a schematic view for explaining an embodiment of a steel cutting apparatus that can suitably carry out the steel cutting method of the present invention, and FIG. 2 is a current adjusting means 40 shown in FIG. FIG. Hereinafter, parts common to the cutting apparatus 50 of FIG. 6 described above are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 1, the cutting device 1 of this embodiment further includes an electrical insulator 20, a current adjusting means 40, a power source 41, and a rotary connector 80, as compared with the conventional cutting device 50 as shown in FIG. ing.

  The electrical insulator 20 includes a cutting tool attachment body (not shown) of the apparatus main body 60 and the cutting tool 30 so that the cutting tool 30 attached to the apparatus main body 60 and the apparatus main body 60 are electrically insulated. It is arranged between. The electrical insulator 20 is not particularly limited as long as it is an electrically insulating material such as rubber and is a non-conductive material. Moreover, if the material of the cutting tool attachment body is a non-conductive material, the electrical insulator 20 may not be disposed.

  Thus, by providing the electrical insulator 20, it is possible to prevent a current from flowing through the work material 10-the apparatus body 60-the cutting tool 30 as an electrical closed circuit. The electrical insulator 20 is disposed between the work material 10 and the apparatus main body 60 (specifically, the chuck 61) to electrically close the work material 10-the apparatus main body 60-the cutting tool 30. It is also possible to prevent the circuit current from flowing.

  The current adjusting means 40 is a means for adjusting the current by flowing between the work material 10 and the cutting tool 30, and one end of the wiring 40 a is connected to the power source 41. It is connected to the work material through a rotary connector 80 attached to the workpiece. Further, one end of the wiring 40b is connected to the cutting tool 30, and the work material 10 can be energized from the cutting tool 30.

  As shown in FIG. 2, the current adjusting unit 40 includes resistors 42 to 46, a 3 WAY switch 47, and an ammeter 48. The resistors 43 and 46 are variable resistors, and the current flowing between the work material 10 and the cutting tool 30 can be adjusted by variably adjusting the resistance value while viewing the display of the current value of the ammeter 48. Adjustments are made.

  As a specific current adjustment method, first, the variable resistance is connected to the contact 47a of the 3WAY switch 47, an electrical closed circuit is formed in the current adjustment means 40, and the current value display of the ammeter 48 is viewed. The current to be passed between the work material 10 and the cutting tool 30 is set by adjusting at 43. When the adjustment of the current value is completed, by connecting to the contact 47b of the 3WAY switch 47, the electric current adjustment means 40-rotary connector 80-workpiece 10-cutting tool 30 as shown by the broken line in FIG. A closed circuit is formed, and a regulated current can flow between the work material 10 and the cutting tool 30. The fine adjustment of the current is performed by the variable resistor 46.

  In such an apparatus configuration, the cutting tool 30 attached to the apparatus main body 60 and the apparatus main body 60 are electrically insulated, and a predetermined current is passed between the cutting tool 30 and the work material 10. However, the workpiece 10 is cut using the cutting tool 30 under predetermined cutting conditions.

  Further, the work material 10 of the present embodiment is a free-cutting steel containing at least B, N, and Al, and is a metal material containing Fe as a main material and hexaboron nitride and a simple substance of Al. . By using such a material, a protective film made of AlN can be formed on the surface of the cutting tool 30 during cutting.

  Examples of the material for the cutting tool include cemented carbide, cermet, and the like. In particular, a cutting tool containing AlN is more suitable because of its good affinity with the protective film of AlN.

  At the time of cutting this free-cutting steel (BN free-cutting steel), the wear is suppressed by the protective film made of AlN formed on the surface where the tool is worn, but a predetermined amount is provided between the free-cutting steel and the cutting tool. By forming an AlN protective film on the cutting surface of the tool that wears when the free-cutting steel and the cutting tool come into contact with each other, the wear of the flank and rake surface of the tool is reduced and the tool length is reduced. Life can be extended.

Hereinafter, Examples 1 and 2 of the present invention will be described in comparison with Comparative Examples 1 and 2.
Example 1
Example 1-1: S45C-BN steel shown in Table 1 was used as a work material, and a carbide tool P30 (SNMN120408) was used as a cutting tool. As in the above-described embodiment, the cutting tool and the apparatus main body were electrically insulated, and a constant current was passed from the cutting tool to the work material (this direction being positive). In this state, cutting was performed under conditions of a dry state (no coolant used) at a cutting speed of 200 m / min, a cutting depth of 0.5 mm, a feed rate of 0.1 mm / rev, a cutting time of 10 minutes. Further, cutting was performed in a current value range of 0 mA to 20 mA.

  Example 1-2: Different from Example 1-1 in that the direction of current flow was changed from the work material to the cutting tool (negative direction), and the others were cut under the same conditions as Example 1-1. .

(Comparative Example 1)
Comparative Example 1-1: S45C shown in Table 1 was used as the work material, and the current value was adjusted in the range of 0 mA to 10 mA. Other than that, cutting was performed under the same conditions as in Example 1-1. It was.

  Comparative Example 1-2: Different from Comparative Example 1-1 in that the direction of current flow was changed from the cutting tool to the work material (positive direction), and the others were cut under the same conditions as Comparative Example 1-1. .

  In Example 1 and Comparative Example 1, the flank wear VB and the maximum crater depth KT were measured for each adjusted current value. The results are shown in FIGS. 3 (a) and 3 (b). Here, the flank wear VB indicates the length of wear in the cutting direction on the flank of the tool, which is worn by contact between the cutting tool 30 and the work material 10, as shown in FIG. Further, the maximum crater depth KT indicates the maximum depth of the crater formed when the tool rake face is worn by the chips 10a on the tool rake face.

  As shown in FIG. 3B, in the case of Example 1-1 (▲) and Example 1-2 (▽), when a current of 5 mA or more flows between the work material and the cutting tool, The maximum crater depth KT has decreased. Further, when the current flowing between the work material and the cutting tool is 10 mA or less, as shown in FIG. 3A, the value of the flank wear VB decreases, and the flank wear is suppressed. However, when the current value exceeded 10 mA, the value of flank wear VB increased. Further, the values of the flank wear VB and the maximum crater depth KT of Example 1-1 (（) and Example 1-2 (▽) were comparable.

  On the other hand, in the case of Comparative Example 1-1 (●), when the current value was increased, the value of the flank wear VB decreased, but the maximum crater depth KT increased. In Comparative Example 1-2 (◯), when the current value was increased, the maximum crater depth KT decreased, but the value of the flank wear VB increased.

(Evaluation 1)
From the above results, when S45C-BN steel was used as the work material and current was passed between the work material and the cutting tool as in Example 1, the current direction was any direction. However, it has been found that the life of the cutting tool is improved. In particular, it has been found that when the current value is adjusted in the range of 5 mA to 10 mA, the flank wear VB and the maximum crater depth KT are both reduced, and the tool life is improved.

  However, as in Comparative Example 1, when S45C was used as the work material and a current was passed between the work material and the cutting tool, the flank wear and the maximum crater depth were larger than those of Example 1. At the same time, only the flank wear VB or the maximum crater depth KT wear is suppressed with respect to the current direction, and it cannot be understood that the life of the cutting tool is improved.

  The reason why the wear of the tool is suppressed in Example 1 is that when a current of a specific value flows, the elements of Al and N contained in the work material cause a chemical reaction, and the work material comes into contact. It is considered that the protective film of AlN is formed on the rake face and the flank face (cutting surface) of the cutting tool which is easily worn, and the formation of the protective film is not affected by the direction of the current. Understandable.

(Example 2)
Example 2-1: A current of 5 mA was passed from the cutting tool to the work material (in the positive direction), and the other cutting conditions were the same as in Example 1-1, and cutting was performed by changing the cutting speed.

  Example 2-2: A current of 5 mA was passed from the work material to the cutting tool (in the negative direction), and other cutting conditions were the same as in Example 2-1, and cutting was performed.

(Comparative Example 2)
Comparative Example 2: Unlike Example 2-1, the cutting tool and the apparatus main body were not electrically insulated, and no current was passed between the cutting tool and the work material. The cutting was performed in the same manner as in Example 2-1.

  In Example 2 and Comparative Example 2, the shear angle φ and cutting resistance were measured for each cutting speed. The results are shown in FIGS. 5 (a) and 5 (b). The shear angle φ is an angle formed by the chips 10a and the work material 10, as shown in FIG. Incidentally, it is shown that the greater the shear angle φ, the smaller the chip thickness and the better the machinability.

  As shown in FIG. 5, in the case of Example 2-1 (▲) and Example 2-2 (▼), the shear angle φ is larger than that of Comparative Example 2 (Δ), and the cutting speed is 100 m / The cutting resistance was smaller than that in Comparative Example 2 between min and 300 m / min.

(Evaluation 2)
From these results, in Example 2, the cutting tool and the apparatus main body are electrically insulated, and an electric current is passed between the work material and the cutting tool, so that the protective film of AlN on the surface of the cutting tool is obtained. As a result, it is considered that as a result, the shear angle φ increases, the chip thickness decreases, the cutting resistance decreases, and the machinability improves.

  Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention described in the claims. Design changes can be made. In the present embodiment, an electrical insulator is provided so as to prevent a current from flowing in the form of an electrical closed circuit of the work material, the apparatus main body, and the cutting tool. An electrical insulator or the like may be provided inside the main body.

  In this embodiment, a DC power supply is provided in the voltage adjusting means in order to flow the current flowing between the cutting tool and the work material in a stable manner. A power source may be used.

  Furthermore, in this embodiment, the free-cutting steel including at least B, N, and Al has been described as the free-cutting steel. However, a protective film can be formed during cutting by the elements contained in the work material. If it is such steel, steel will not be specifically limited.

The schematic diagram for demonstrating the cutting device which concerns on one Embodiment of this invention. FIG. 2 is an electric circuit diagram of the current adjusting means shown in FIG. 1. It is a graph for demonstrating the experimental result of Example 1 which concerns on one Embodiment of this invention, and the comparative example 1, (a) is the figure which showed the relationship between an electric current value and flank wear, b) The relationship between the current value and the maximum crater depth. The figure for demonstrating the evaluation parameter of Example 1 and Comparative Example 1 of FIG. It is a graph for demonstrating the result of the experiment of Example 2 which concerns on embodiment of this invention, and the comparative example 2, (a) is the figure which showed the relationship between cutting speed and a shear angle, (b ) Is a diagram showing the relationship between cutting speed and cutting resistance. The schematic diagram for demonstrating the conventional cutting device.

Explanation of symbols

  1: Cutting device, 10: Work material, 20: Electrical insulator, 30: Cutting tool, 40: Current adjusting means, 41: DC power supply, 42-46: Resistance, 47: 3WAY switch, 48: Ammeter, 60 : Device main body, 80: Rotary connector

Claims (6)

A steel cutting method in which a workpiece attached to the apparatus body is rotated and cut with a cutting tool,
The work material is free-cutting steel containing at least B, N, and Al,
A steel cutting method, wherein an electrical insulation state is provided between the apparatus main body and the cutting tool, and a current of a predetermined value is passed between the cutting tool and the free-cutting steel for cutting.   The steel cutting method according to claim 1, wherein the current is in the range of 5 mA to 10 mA.   The steel cutting method according to claim 1 or 2, wherein a cutting speed during the cutting is in a range of 100 m / min to 300 m / min. A cutting apparatus for executing the steel cutting method according to any one of claims 1 to 3,
The steel cutting device comprises: a power source that generates the current; and a current adjusting unit that adjusts a current flowing from the power source.   The steel cutting device according to claim 4, wherein the cutting device further includes a cutting tool mounting body that is electrically insulated from the device main body. A steel cutting device that rotates a work material attached to the device body and cuts it with a cutting tool,
The cutting apparatus includes an electrical insulator disposed between the apparatus main body and the cutting tool, a power source that generates a current, and a current from the power source that is adjusted between the cutting tool and the work material. Current adjusting means for causing current to flow through,
The current adjusting means is configured to flow a current having a predetermined value optimum for forming a protective film during cutting by an element contained in the work material on a cutting surface of the cutting tool. Steel cutting device.

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