JP4414977B2 - Regeneration method for tools made of high-speed tool steel - Google Patents

Description

  The present invention relates to a method for regenerating a tool made of high-speed tool steel such as a hob, a pinion, an end mill, a drill, and a tap.

  The technique of increasing the surface hardness by nitriding the surface of steel has been practiced for a long time, but in recent years, in order to further increase the surface hardness of tools made of high-speed tool steel, a ceramic coating is applied after nitriding. Processing may be performed. A ceramic film (titanium-based film) formed by this ceramic coating treatment is very excellent in wear resistance, and is therefore often used particularly for dry processing tools. General examples of the ceramic film include TiC, TiN, TiCN, TiAlN, and the like.

In addition, as a prior art regarding a nitriding process and a ceramic coating process, patent document 1 is mentioned, for example, As a prior art regarding a ceramic film | membrane, patent document 2 is mentioned, for example.
JP 2004-131820 A JP 2001-234366 A

  When the rake face of the blade is worn with long-term use, tools made of high-speed tool steel are particularly expensive. . FIG. 5 is an external perspective view of a hob H used for hobbing, for example, a spur gear. As the blade G is enlarged in cross section with long-term use, the rake face F of the blade is mainly used. It will be worn out.

  FIG. 4 shows an example of a hob regeneration method when the rake face F of the blade is worn. FIG. 4 is a cross-sectional view of the arbitrary blade G shown in FIG. 5, in which the surface layer portion is formed as a nitride layer 1 by nitriding treatment and the ceramic film 2 is formed on the surface by ceramic coating treatment. This is shown schematically. FIG. 4A shows a state in which the rake face F is worn. From this state, as shown in FIG. 4B, the ceramic film 2 and the nitride layer 1 on the rake face F are first removed in order to remove the worn portion. Remove. Next, as shown in FIG. 4C, the ceramic film 2 remaining on the flank J or the like is peeled off. Specifically, the step of FIG. 4C is performed by immersing the entire hob H in a solution for removing the ceramic film, as shown in FIG. 6C. Next, as shown in FIG. 4D, the regeneration of the hob H is completed by applying a ceramic coating process to the entire blade G. Specifically, the step of FIG. 4D is performed by placing the hob H in a ceramic film processing apparatus such as a PVD apparatus, as shown in FIG. 6B.

  However, according to this reproduction method, as is apparent from the drawing of FIG. 4D, the ceramic film 2 is formed directly on the rake face F without the nitride layer 1 being interposed. There is a problem in that the hardness of the rake face F is lowered by the amount not interposed. At first glance, this problem seems to be solved if a nitriding step is inserted between the step of FIG. 4C and the step of FIG. 4D. This causes another problem that the nitrided layer 1 on the flank J side is subjected to nitriding again. It is well known that when the nitrided layer 1 formed to a predetermined hardness is nitrided again, the amount of nitrogen is excessive and the material easily becomes brittle. 4 (d) is performed without performing nitriding treatment. Note that, after the step of FIG. 4C, it may be possible to perform nitriding only on the rake face F by separately performing a masking process or the like on the flank J, but it is extremely difficult to implement this method. is there.

  The present invention was devised to solve the above-mentioned problems, and is a method for regenerating a tool made of high-speed tool steel that is simple and excellent in economic efficiency, and can obtain the hardness of a rake face equivalent to that of a new product. It is intended to provide.

  In order to solve the above-mentioned problems, the present invention relates to a tool made of high-speed tool steel that has been subjected to nitriding treatment and ceramic coating treatment, and is a method for regenerating a rake face of a worn blade, and (A) blade rake The step of removing the ceramic film and nitride layer on the surface, and then (B) the entire tool is placed in a nitriding atmosphere while leaving the ceramic film on the portion other than the rake face of the blade, and only the rake face of the blade is nitrided A method for regenerating a tool made of high-speed tool steel, characterized in that the step is performed.

  According to this regeneration method, first, in the step (A), only the rake face is exposed to the surface of the high-speed tool steel that has not been surface-treated. In this state, when the tool is placed in the nitriding atmosphere in the step (B), the nitriding layer remaining on the portion other than the rake face is prevented from being nitrided again by the ceramic film formed on the surface. The Therefore, only the rake face of the tool is nitrided.

  Further, in the present invention, after the step (B), (C) the step of removing the ceramic film of the entire tool, and then (D) the entire tool is placed in a ceramic coating treatment atmosphere to perform the ceramic coating treatment. The step of applying is a method for regenerating a tool made of high-speed tool steel.

  According to this reproduction method, the nitrided layer and the ceramic film of the tool after the reproduction are formed in the same manner as when new. Thereby, the service life of the tool can be extended.

  In addition, the present invention provides a ceramic coating treatment by placing the entire tool in a ceramic coating treatment atmosphere after leaving the ceramic membrane in a portion other than the rake face of the blade (E) after the step (B). The step of applying is a method for regenerating a tool made of high-speed tool steel.

  According to this regeneration method, the formation mode of the nitride layer and the ceramic film on the rake face after regeneration becomes equivalent to that of the new one, and the service life of the hob H can be extended.

  Further, the present invention provides a method for regenerating a tool made of high-speed tool steel, wherein the step (A) is performed by grinding.

  According to this regeneration method, the nitride layer on the rake face can be removed easily and reliably.

  Further, the present invention provides a method for regenerating a tool made of high-speed tool steel, wherein the tool is a hob.

  According to this regeneration method, the service life of the hob can be extended.

  According to the present invention, it is a tool regeneration method that is simple and excellent in economic efficiency and that can obtain the hardness of a rake face equivalent to that of a new article.

  Hereinafter, a mode for reproducing the hob H shown in FIG. 5 will be described. FIG. 1 is an explanatory diagram showing the appearance of the nitride layer 1 and the ceramic film 2 of the blade G in the main steps of the regeneration method according to the present invention.

  In FIG. 1, the leftmost figure shows a state where the central portion of the rake face F of the blade G is worn. From this state, the present invention (A) removes the ceramic film 2 and the nitrided layer 1 on the rake face F of the blade, and then (B) leaves the ceramic film 2 in a portion other than the rake face F of the blade. The main feature is that the entire hob H is placed in a nitriding atmosphere and only the rake face F of the blade is nitrided.

  By the step (A), only the rake face F is exposed to the surface of the high-speed tool steel that is not surface-treated. In this state, that is, in a state where the ceramic film 2 is left in a portion other than the rake face F, the hob H is placed in the nitriding atmosphere. Specifically, as shown in FIG. 6A, the hob H is placed in the nitriding apparatus. The thickness of the ceramic film 2 is about 3 to 5 microns.

  Here, in general, the Vickers hardness of the high-speed tool steel that has not been surface-treated is about 780 Hv, and can be increased to about 1000 Hv by performing nitriding, and further by applying a ceramic coating such as TiAlN. The hardness can be increased to about 3000 Hv. Thus, the hardness when the ceramic film is formed is much larger than the hardness when only the nitriding treatment is performed. This is because the molecular bond in the ceramic film is denser than that of the nitride layer. It is presumed to be caused. Therefore, in the step (B), nitrogen hardly penetrates the ceramic film 2, and the ceramic film 2 has a function of preventing renitridation of the nitride layer 1 at the flank J. Thereby, the hob H is nitrided only on the rake face F. Strictly speaking, the corner portion between the rake face F and the flank face J is renitrided, but the thickness of the nitride layer 1 is about 100 microns, and the range is extremely small. Therefore, the effect of the present invention is not significantly affected.

  As described above, according to the regeneration method in which the steps (A) and (B) are performed, the rake face F can be nitrided while preventing nitridation on the flank J or the like. Thereby, for example, the rake face F can be raised to a hardness equivalent to that at the time of a new article by performing a ceramic coating process in a later step. Since the process (B) is realized simply by putting the hob H into the nitriding apparatus, it is simple and economical.

  As the step (A), the surface layer of the rake face F may be removed by chemical treatment. However, if the nitride layer 1 (and the ceramic film 2) is removed by grinding, nitriding is simple and reliable. Layer 1 (and ceramic membrane 2) can be removed.

  The dimension of the grinding width needs to be equal to or greater than the thickness of the nitrided layer 1 so that a portion to be nitrided again on the rake face F does not remain. However, it should be noted that if the size of the grinding width is increased more than necessary, the size of the blade to be ground is limited, so that the number of times it can be regenerated is reduced and it becomes uneconomical.

  In the present embodiment, as described above, since the thickness of the nitride layer 1 is approximately 100 microns, it is preferable that the grinding width is in the range of 0.1 mm to 0.5 mm. Among these, a more preferable grinding width is 0.3 mm, which is a grinding width that achieves both reliable removal of the nitride layer 1 and economical efficiency in terms of the number of regenerations.

  Next, the case where the ceramic coating process is performed after the step (B) will be described with reference to two examples. FIG. 2 is an explanatory view showing a first example in the case of performing a ceramic coating process after the step shown in FIG. In the first example, after the step (B), (C) the step of removing the ceramic film 2 of the entire hob H, and then (D) the entire hob H is placed in the ceramic coating treatment atmosphere, thereby performing the ceramic coating treatment. The process of giving is performed.

  The step (C) is performed by immersing the hob H in a solution for removing the ceramic film, as shown in FIG. The step (D) is performed by placing the hob H in a ceramic film processing apparatus as shown in FIG.

  Thus, if it is the reproduction | regenerating method which performs the process of (C) and (D) after the process of (B), the formation aspect of the nitride layer 1 and the ceramic film | membrane 2 in the blade G will become equivalent to the thing at the time of a new article. Thereby, the service life of the hob H can be extended.

  FIG. 3 is an explanatory view showing a second example in the case of performing a ceramic coating process after the step shown in FIG. In this second example, after the step (B), (E) the entire hob H is placed in the ceramic coating treatment atmosphere while leaving the ceramic film 2 in the portion other than the rake face F of the blade, thereby providing a ceramic coating. A process of applying a treatment is performed. That is, in the first example, all the ceramic films 2 remaining after the step (B) are once removed and then the ceramic coating process is performed, whereas in the second example, the ceramic films 2 are formed. Without removing, the ceramic coating is performed immediately after the step (B).

  The step (E) is performed by placing the hob H in a ceramic film processing apparatus as shown in FIG. 6 (b). Also according to the second example, the formation mode of the nitride layer 1 and the ceramic film 2 on the rake face F becomes equivalent to that of the new one, and the service life of the hob H can be extended. In the second example, the removal process of the ceramic film 2 is not required, and therefore, the regeneration method is simpler and more economical than the first example. However, since the ceramic film 2 is formed by polymerization on the flank J or the like, it is necessary to pay attention to the dimension management of the blade G.

"Example"
As a verification that the ceramic film 2 has a function of preventing renitridation of the nitride layer 1, a comparative test as shown in FIG. 7 was performed. (A) is a case where the nitride layer 1 is formed with an excessive amount of nitrogen than usual by nitriding the blade G of the new hob H not subjected to nitriding treatment or ceramic coating treatment 10 times. (B) shows that a new hob H is put in a ceramic film processing apparatus to perform ceramic film processing (TiAlN), and then the rake face F is ground to form the ceramic film 2 only on the flank J. This was nitrided 10 times under the same conditions as in (a). The thickness of the ceramic film 2 is about 3 to 5 microns. With each of these nitridized hobbs H, the same number of shots for removing polishing burrs from the gear to be processed were performed. The state of the edge part of the blade G at that time is shown in FIG. 8A and 8B show the results of FIGS. 7A and 7B, respectively.

  When the hob H in which the ceramic film 2 is not formed as shown in (a) is repeatedly nitrided a plurality of times, the re-nitridation portion weakens, and even the shot processing such as removal of polishing burrs can cause minute peeling of the edge portion. Although it occurred, in the case of (b), almost no peeling of the edge portion was confirmed. This is presumed to be a result of preventing the edge portion from being weakened because at least the nitride layer that would cause an excessive amount of nitrogen was not formed on the flank J. From the above, it can be easily estimated that the ceramic film 2 has a function of suppressing permeation of nitrogen and preventing renitridation of the nitride layer 1.

  The preferred embodiments of the present invention have been described above. The present invention is not limited to a hob, and can be applied to any tool made of high-speed tool steel having a rake face (surface that is a main body for cutting), such as a pinion, an end mill, a drill, a tap, and a milling cutter.

It is explanatory drawing which shows the mode of the nitrided layer of a hob blade, and the ceramic film | membrane in the main processes of the reproduction | regenerating method based on this invention. It is explanatory drawing which shows the 1st example in the case of performing a ceramic film process after the process shown in FIG. It is explanatory drawing which shows the 2nd example in the case of performing a ceramic coating process after the process shown in FIG. It is process explanatory drawing which shows the reproduction | regenerating method of the conventional hob. It is an external appearance perspective view which shows an example of a hob. (A)-(c) is explanatory drawing which shows a mode that the hob was put in the nitriding processing apparatus, the mode which was put in the ceramic film processing apparatus, and the state immersed in the solution for ceramic film peeling, respectively. It is a figure which shows the conditions of the comparative test for verifying that a ceramic film | membrane has the function to prevent renitridation of a nitride layer. (A) is a case where a nitrided layer is formed with an excessive amount of nitrogen than usual by nitriding a new hob blade not subjected to nitriding treatment or ceramic coating treatment 10 times. In (b), a new hob is put in a ceramic film processing apparatus to perform ceramic film processing, and then the rake surface is ground so that a ceramic film is formed only on the flank surface. ) And nitriding 10 times under the same conditions. The state of the edge part of a blade is shown as an external appearance photograph. (A) and (b) correspond to (a) and (b) of FIG. 7, respectively.

Explanation of symbols

1 Nitrided layer 2 Ceramic film H Hob (tool)
F Blade rake face G Blade

Claims (5)

Regarding a tool made of high-speed tool steel subjected to nitriding treatment and ceramic coating treatment, a method for regenerating a rake face of a worn blade,
(A) removing the ceramic film and the nitride layer on the rake face of the blade;
Next, (B) a step of nitriding only the rake face of the blade, placing the entire tool in a nitriding atmosphere while leaving the ceramic film in a portion other than the rake face of the blade,
A method for regenerating a tool made of high-speed tool steel. After the step (B),
(C) removing the ceramic film from the entire tool;
Next, (D) placing the entire tool in a ceramic coating treatment atmosphere to perform ceramic coating treatment,
The method for regenerating a tool made of high-speed tool steel according to claim 1, wherein: After the step (B),
(E) A step of applying a ceramic coating by placing the entire tool in a ceramic coating treatment atmosphere while leaving a ceramic membrane in a portion other than the rake face of the blade;
The method for regenerating a tool made of high-speed tool steel according to claim 1, wherein:   The method for regenerating a tool made of high-speed tool steel according to any one of claims 1 to 3, wherein the step (A) is performed by grinding.   The method for regenerating a tool made of high-speed tool steel according to any one of claims 1 to 4, wherein the tool is a hob.