JPH09253934A - Screw processing tool and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw processing tool with high screw precision and long life in which the discharge of chip is facilitated by providing a land and a groove spirally formed around a central axis. SOLUTION: A groove 4 spirally turned around a central axis is machined on a tap material to form a land 6. The capacity portion of a super abrasive particle sintered body 7 to be fixed to the front surface of the land 6, and the super abrasive particle sintered body 7 manufactured separately is fixed thereto by brazing. In the case of screw machining tool having a relatively small diameter, the whole screw part mat be formed of the super abrasive particle sintered body. As the super abrasive particle, diamond abrasive grain or CBN abrasive particle is used. The land 6 and the groove 4 are spirally formed around the central axis, whereby the discharge of chip is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw processing tool and a method for manufacturing the same. More specifically, the present invention relates to a screw such as a spiral tap having a superabrasive grain sintered body at a cutting edge, in which a land and a groove are spirally formed around a central axis, and which has a high processing accuracy and a long life. Processing tool and
The present invention relates to a method for manufacturing a screw machining tool by die-sinking electric discharge machining using a thread-shaped forming electrode.

[0002]

2. Description of the Related Art A threading tool is a tool that is widely used in machining, and it is screwed into a prepared hole that has already been drilled and tapped. FIG. 1 is a perspective view of a typical example of a screw processing tool. Screw processing tools
It comprises a screw portion 1, a shank 2, and a shank square portion 3.
By providing a plurality of grooves 4 in the screw portion, a plurality of lands 6 having cutting edges as discontinuous threads 5 are provided.
Is formed. Conventionally, cemented carbide and high speed tool steel have been often used as materials for screw working tools.
In the screw machining tool made of such a material, the chemical affinity between the work material and the tool material is large, and the viscosity of the work material is high, so that a large machining allowance per turn cannot be taken. There is a problem that the screw accuracy is deteriorated due to the attachment of cutting chips as the process becomes long. The inventors of the present invention previously proposed a screw machining tool having a superabrasive grain sintered body at the cutting edge in Japanese Patent Laid-Open No. 7-60547, and as a method of manufacturing the screw machining tool, the surface of each land is provided along the axial circumference. A method of forming a cutting edge in a spiral shape of a thread by wire electric discharge machining has been disclosed. According to this screw processing tool, the cutting resistance is small, and the chips are unlikely to adhere to the cutting edge. As a result, the screw accuracy is improved and the screw processing tool has a long life. It is known that, in a thread processing tool, the land and groove are spirally formed around a central axis to facilitate discharge of chips and improve cutting performance. FIG.
[FIG. 4] is a side view of a screw portion having a land and a groove that are spirally swung. However, in the wire electric discharge machining, although the screw machining tool having the shape of FIG. 1 in which the land and the groove are parallel to the central axis can be easily manufactured, the land and the groove are spirally rotated around the central axis. It was difficult to manufacture a screw processing tool in the shape of. Further, there is a problem that it is impossible to perform round land relief processing, so-called hacking processing, depending on the wire electric discharge machining.

[0003]

DISCLOSURE OF THE INVENTION The present invention has a superabrasive grain sintered body at the cutting edge, and lands and grooves are spirally formed around a central axis so that chips can be easily discharged. The object of the present invention is to provide a screw processing tool having high screw accuracy and a long life, and a method for manufacturing the same.

[0004]

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that a material having a superabrasive sintered body in the cutting edge portion is provided with a thread-shaped forming electrode. It was found that by performing die-sinking electric discharge machining using the screw, it is possible to easily produce a screw machining tool in which a land and a groove are spirally swung around a central axis, and the present invention is based on this finding. It came to completion. That is, the present invention is (1) a screw working tool having a superabrasive grain sintered body at the cutting edge, wherein the land and the groove are formed by spirally turning around a central axis. Screw processing tools,
(2) Super abrasive grains are diamond or CBN (1)
The thread processing tool described in paragraph (3), and (3) a super-abrasive sintered body is fixed to a portion of the material for the thread processing tool, which is a cutting edge, and the thread for the thread processing tool is rotated around the central axis, The screw machining according to item (1) or (2), wherein the shape of the shaped electrode is transferred to a material for a screw machining tool by performing die-sinking electric discharge machining to form a screw shape. A method for manufacturing a tool is provided.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 3 is a perspective view of an aspect of the screw machining tool of the present invention. The screw machining tool of the present invention has the same overall shape as a known screw machining tool, and is composed of a screw portion 1, a shank 2, and a shank square portion 3, and a land 6 and a groove 4 of the screw portion have a central axis. A spiral cutting edge is formed around the land, and a cutting edge is formed as a discontinuous thread 5 on the land, but a superabrasive grain sintered body 7 is provided on the cutting edge located on the front surface of the land. In the screw processing tool of the present invention, diamond abrasive grains or CBN abrasive grains can be used as the superabrasive grains for forming the superabrasive grain sintered body. Mixing metal or ceramic as a sintering aid into diamond abrasive grains or CBN abrasive grains, and applying high temperature and high pressure conditions (1,300 to 1,500).
A sintered body can be obtained by sintering at a temperature of 5 to 6 × 10 ⁴ atm). In the present invention, there is no particular limitation on the method of fixing the superabrasive sinter to the cutting edge portion of the screw machining tool material, for example, the cylindrical metal edge portion that is the raw material of the screw machining tool. , A recess corresponding to the thickness and depth of the superabrasive grain sintered body is processed, the mixture of the superabrasive grain and the powder for sintering is filled in the recess, and the superabrasive grain is directly filled in the recess. A sintered body can be produced and fixed to a material for a screw processing tool. Alternatively, a groove for spirally turning around the central axis is processed in the material for a screw processing tool to form a land, and the volume of the superabrasive sintered body to be fixed to the front surface of the land is scraped off and separately cut. The superabrasive grain sintered body produced in step 1 can be fixed by brazing or the like. With a screw processing tool having a relatively small diameter, the entire screw portion can be made into a superabrasive sintered body. In the thread processing tool of the present invention, the material of the thread portion other than the superabrasive grain sintered body is not particularly limited, and includes, for example, WC-Co type and WC-TiC.
-Co-based cemented carbide, W, Co, low C-high Co, low W,
Mo high speed steel or the like can be used. The material of the shank and the shank square portion is not particularly limited, and, for example, an iron-based metal such as SK material can be used.

FIG. 4 is an explanatory view showing a cross-sectional shape of a screw portion of the screw processing tool of the present invention. The screw machining tool of this figure has four lands 6 and four grooves 4 in the threaded portion. A super abrasive grain sintered body 7 is attached to the front surface of each land. Since the cutting edge 8 of the screw thread 5 is made of a super-abrasive grain sintered body, the work material is first contacted with the super-abrasive grain sintered body portion of the cutting edge of the screw thread when the screw is machined, and extremely excellent cutting performance is exhibited. . The screw thread of the thread processing tool is equidistant from the shaft center to the margin 9, that is, on the same circumference, but the distance from the shaft toward the rear end of the blade becomes shorter, Enter the inside to form a round land relief 10. In this figure, the circumference is indicated by a broken line for easy understanding.
It is indispensable for the screw processing tool to have a relief for the round land, and when there is no relief for the round land, the cutting resistance is remarkably large, and practicality as a screw processing tool is almost lost. According to the conventional wire electric discharge machining method, in the screw machining tool, it was impossible to machine the relief of the round land when the land and the groove spirally swivel around the central axis. On the other hand, according to the method of the present invention, even if the land and the groove are spirally swiveled around the central axis, the relief of the round land can be processed very easily. Further, according to this method, a screw machining tool having a land and a groove parallel to the central axis, or a screw machining tool having no groove can be manufactured more easily than the conventional wire electric discharge machining method. Needless to say. FIG.
FIG. 4 is an explanatory diagram of a rough machining process of the screw machining tool of the present invention. The formed electrode 11 has a large number of threads having the same pitch as that of the screw machining tool. The material 12 for a screw processing tool and the forming electrode 11 are rotated in the same direction at the same rotation speed,
While maintaining the positional relationship in which the central axes are parallel to each other, electric discharge machining is performed in a direction in which the axes approach each other, and the shape of the forming electrode is transferred to the material for a screw machining tool. When an electrode having a groove having a thread cross section parallel to the central axis is used as the forming electrode, the forming electrode moves in the axial direction by a pitch for each rotation while rotating. There is no particular limitation on the material of the thread-shaped forming electrode to be used, and an electrode made of a known material for electric discharge machining can be used, and examples thereof include CuW. At the time of electric discharge machining, a known machining liquid can be jetted if necessary.

FIG. 6 is an explanatory view of the finishing process of the screw machining tool of the present invention. In the finishing process, the relief of the round land is further processed for each mountain in the screw processing tool to which the screw shape is transferred in the roughing process. The screw forming tool material 14 having the screw shape transferred around the periphery of the screw-shaped forming electrode 13 having two ridges that rotate in the direction of arrow A, that is, one groove, maintains a positional relationship parallel to the electrode, and While rotating in the direction of B, it moves upward or downward and discharges between the electrode and the material for screw processing tools to release the round land for each crest of the material for screw processing tools to which the screw shape is transferred. To process. There is no particular limitation on the material of the thread-shaped forming electrode to be used, and an electrode made of a known material for electric discharge machining can be used, and examples thereof include CuW. At the time of electric discharge machining, a known machining liquid can be jetted if necessary. FIG. 7 is an explanatory diagram of relief processing of a round land. This drawing is a view of the electric discharge machining state of FIG. 6 observed from below. For the screw processing tool material 14 on which the screw shape that rotates in the direction of arrow B is transferred,
Since the thread-shaped forming electrode 13 moves along the arrow C while rotating in the direction of the arrow A, even if the land and the groove spirally rotate around the central axis, the round land is released. Can be processed on the threads of the material for screw processing tools. FIG. 8: is explanatory drawing of one aspect of the manufacturing method of the screw machining tool by the conventional wire electric discharge machining method. The material 12 for a screw processing tool rotates at a fixed position in the direction of the arrow D, and an electric discharge is generated between the material 12 for the screw processing tool and the wire 15 running in the vicinity thereof in the direction of the arrow E to process the thread. FIG. 9 is an explanatory diagram of one mode of a method for manufacturing a screw machining tool by a conventional wire electric discharge machining method, and is a drawing in which the state of electric discharge machining in FIG. 8 is observed from the left side. Electric discharge is generated between the material 12 for a screw processing tool which rotates in the direction of arrow D and the wire 15 which runs in the direction of arrow E, but when the land and the groove spirally rotate around the central axis. Has a shape in which the outer peripheral end of the screw thread 5 is on the same circumference from the cutting edge to the rear end, and the escape of the round land cannot be formed. If a round land relief is to be machined in a screw machining tool of such a shape manufactured by wire electric discharge machining, it is extremely complicated process to grind the screw threads one by one with a grindstone. According to the method of the present invention, the shape of the thread-shaped forming electrode is transferred while rotating the material for a screw processing tool, so that even if the land and the groove spirally rotate around the central axis. It can be manufactured. Also, compared with the conventional wire electric discharge machining method, the machining time has been shortened by half,
The processing accuracy is improved, the runout is reduced to about 1/5, and the surface roughness is also improved.

[0008]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 Four diamond abrasive grain sintered bodies were fixed in a spiral shape on the outer peripheral portion of a cemented carbide having a diameter of 30 mm, and tap processing was performed using this as a material. As an electrode, a thread-shaped copper tungsten material CuW having a diameter of 29 mm, 12 threads with a pitch of 1.5 mm and a valley depth of 1.6 mm [Nihon Tungsten]
Manufactured by K.K.] was used for roughing, and a shaped electrode having the same size and material and two screw threads was used for finishing. The rough machining electrode and the tapping material are arranged so that their center axes are parallel to each other, and the electrode is rotated at 200 min ^-1 and the tapping material is rotated at 1 mm ^-1 with a rotation pitch of 2 mm in the state shown in FIG. Then, electrical discharge machining was performed while jetting Vitele V2 (manufactured by KHS Co., Ltd.) as a machining fluid at 1.0 kg / cm ² , and rough machining was performed for 2 hours and 30 minutes. The screw shape of the formed electrode was accurately transferred to the tap material. Next, electric discharge machining was performed in the state shown in FIG. 6 by using the finishing electrode, the round land was released for each mountain, and the finishing process was completed in 2 hours. Further, the groove and the land are processed to have a superabrasive sintered body on the cutting edge, M30 × P
A 1.5- and 4-blade spiral tap was obtained. Using this tap, screw cutting was performed on an automobile part made of ADC-12 under the conditions of a rotation speed of 190 min ^-1 , a cutting speed of 18 m / min and a feed rate of 1.5 mm / rev. It was possible to process 1,500,000 pieces with one tap. Comparative Example 1 Using a commercially available cemented carbide M30 × P1.5, 4-blade spiral tap, under the same conditions as in Example 1, Example 1
The same automobile parts as above were cut with screws. The total number of processing with one tap was 100,000. Comparative Example 2 A M30 × P1.5, 4-blade straight-shaped tap having a superabrasive grain sintered body at the cutting edge was produced by wire electric discharge machining. Using this tap, the same automobile parts as in Example 1 were subjected to screw cutting under the same conditions as in Example 1. 1
The total number of machining with taps of the book was 90,000. Example 2 In the same manner as in Example 1, a cemented carbide having a diameter of 20 mm in which four diamond abrasive grain sintered bodies were fixed in a spiral shape on the outer periphery was used as a material, and screw-shaped transfer and round land relief were performed by electric discharge machining. Processing, further processing grooves and lands, and having a superabrasive sintered body on the cutting edge, M20 × P1.5,
A 4-blade spiral tap was obtained. With this tap,
Rotation speed 190min ^-1 , cutting speed 12m / min, feed amount 1.
Under the condition of 5 mm / rev, a screw was cut on an automobile part made of ADC-10. With one tap,
It was possible to process, 000,000 pieces. Comparative Example 3 Using a commercially available cemented carbide M20 × P1.5, 4-blade spiral tap, under the same conditions as in Example 2, Example 2
The same automobile parts as above were cut with screws. The total number of processing with one tap was 100,000. Comparative Example 4 A M20 × P1.5, 4-blade straight-shaped tap having a superabrasive grain sintered body at the cutting edge was produced by wire electric discharge machining. Using this tap, the same automobile parts as in Example 2 were subjected to screw cutting under the same conditions as in Example 2. 1
The total number of taps processed was 450,000. The results of Examples 1 and 2 and Comparative Examples 1 to 4 are summarized in Table 1.

[0009]

[Table 1]

From the results in Table 1, Example 1 and Example 2
The spiral-shaped tap of the present invention having a superabrasive grain sintered body at the blade edge thereof is superior in sharpness to the conventional cemented carbide spiral-shaped taps of Comparative Example 1 and Comparative Example 3, and is 10 to 15 times as sharp. It has a long life, and is excellent in the chip discharge property as compared with the straight tap having the superabrasive sintered body on the cutting edge of Comparative Example 2 and Comparative Example 4, and has a life of 1.6 to 2.2 times. It turns out that

[0011]

EFFECTS OF THE INVENTION The screw processing tool of the present invention is excellent in sharpness, discharges chips easily, has high screw precision, and has a long life. In addition, the screw machining tool can be manufactured accurately in a short time by the method of the present invention utilizing die-sinking electric discharge machining.

[Brief description of drawings]

FIG. 1 is a perspective view of a typical example of a screw machining tool.

FIG. 2 is a side view of a screw portion having a spirally-wound land and groove.

FIG. 3 is a perspective view of an embodiment of the screw machining tool of the present invention.

FIG. 4 is an explanatory view showing a cross-sectional shape of a screw part of the screw processing tool of the present invention.

FIG. 5 is an explanatory diagram of a rough machining process of the screw machining tool of the present invention.

FIG. 6 is an explanatory diagram of a finishing process of the screw machining tool of the present invention.

FIG. 7 is an explanatory diagram of relief processing of a round land.

FIG. 8 is an explanatory diagram of one mode of a method for manufacturing a screw machining tool by a conventional wire electric discharge machining method.

FIG. 9 is an explanatory diagram of one mode of a method for manufacturing a screw machining tool by a conventional wire electric discharge machining method.

[Explanation of symbols]

 1 Screw Part 2 Shank 3 Shank Square Part 4 Groove 5 Screw Thread 6 Land 7 Super Abrasive Sintered Body 8 Cutting Edge 9 Margin 10 Relief of Round Land 11 Groove Shaped Electrode with Many Screw Threads 12 Screw Processing Tool Material 13 Screw-shaped forming electrode having 2 screw threads 14 Material for screw processing tool with transferred screw shape 15 Wire

Claims (3)

[Claims] 1. A screw processing tool having a superabrasive grain sintered body at a cutting edge, wherein a land and a groove are spirally formed around a central axis and formed. 2. The screw machining tool according to claim 1, wherein the superabrasive grains are diamond or CBN. 3. A shape of a thread-shaped forming electrode while a superabrasive sintered body is fixed to a portion of a material for a screw processing tool, which is a cutting edge, and the material for a screw processing tool is rotated around a central axis. To
The method for manufacturing a screw machining tool according to claim 1 or 2, wherein the screw machining tool is transferred to a material for a screw machining tool to form a screw shape by die-sinking electric discharge machining.