JPH10146720A - Cemented carbide solid hob - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cemented carbide-made hob by which a broken piece of an edge is not caused and which is excellent in the cutting quality and whose edge can be easily given and reground and which has the long service life, while making the most of a characteristic of high speed cutting being a characteristic of the cemented carbide hob by integrally forming a hob of cemented carbide, and setting the number of cutting edge grooves to the specific number. SOLUTION: As shown in a drawing, a cemented carbide material is integrally formed, and cutting edges 2 having cutting faces are equally arranged on the circumference by 16 to 30 sheets, in this case, 22 sheets on an outer periphery of an almost cylindrical main body 1 having an arbor hole 12 having a key groove 11 integrally with the main body 1 together with cutting edge grooves 3, and are formed in a spiral shape in the shaft direction. In this way, since a cemented carbide material hob is formed as an integral structure, installation of a cemented carbide tip is obviated, and its equivalent quantity can be alloted to an increase in the number of cutting edge grooves. As a result, a notch sharing quantity per a single cutting edge is reduced by half, and impact force to edges 4 of the cutting edges is also reduced, and even if a conventional broken piece measure is not taken against a cemented carbide cutting edge 2, the occurrence of a broken piece can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hob for forming gear teeth.

[0002]

2. Description of the Related Art Hobbing is the most widely used machining method for cutting gear teeth. The tool used for the hobbing is called a hob, and a high-speed (high-speed tool steel) material hob is often used. FIG. 2 shows a conventional high-speed steel material integrally formed. A cutting blade 14 having a rake face on the outer periphery of a substantially cylindrical main body 13 having an arbor hole 12 provided with a key groove 11 has a circular shape. And is spirally formed in the axial direction. The number of cutting edge grooves 15 is 1
The number of grooves is from 0 to 14, and generally, there are many around 12 grooves as shown in FIG. On the other hand, hobbing of a high-speed material has been conventionally performed by a super hard material hob for higher efficiency (high speed cutting) and a longer life.

[0003] The conventional carbide hob is not economical for reasons of FIG.
As shown in FIG. 1, a carbide tip (carbide plate) 2 serving as a cutting blade is provided on a mounting portion 22 formed on a hob body 21 made of, for example, alloy steel.
3 is fixed by brazing, and is manufactured in the same hob shape and the number of cutting grooves as the high-speed steel hob of FIG. However, since the hob blades 24 are arranged at equal intervals on the outer periphery of the hob due to the cutting edge grooves 25, the cutting motion is interrupted by the rotational movement of the hob, and an impact load is applied to the cutting edge 26. At that time, there was a problem that chipping of the cutting edge, which does not occur with a high-toughness high-speed steel hob, occurs in most of the super hard material hobs.

[0004] Therefore, as shown in FIG.
The cutting edge of the cutting edge 24 of the third cutting edge 24 is intentionally provided with a rounded portion 26, or as shown in FIG. 5, the cutting edge of the cutting edge 24 of the carbide tip 23 is chamfered 27, as shown in FIG. By giving a negative rake angle λ to the rake face 28 of the carbide tip 23, measures have been taken to withstand impact. This has been introduced in many documents, and not only the hob but also a cutting tool using a cemented carbide material requires such a technical measure.

[0005]

However, rounding, chamfering, or making a negative rake angle the cutting edge of such a cemented carbide insert not only requires a lot of man-hours in manufacturing, but also requires re-grinding. This procedure has to be performed every time (re-grinding), and the working time for re-grinding is 4 to 6 in some cases.
It was time consuming and troublesome for manufacturers and users. Further, measures such as rounding the cutting edge of the cutting edge of the cemented carbide tip have a problem that the sharpness is reduced, heat is generated, the life of the carbide hob is shortened, and the precision of the workpiece is reduced.

An object of the present invention is to make use of the characteristics of high-speed cutting, which is the characteristic of a carbide hob, without causing chipping and sharpness, making it easy to apply and re-grind, and furthermore, providing a long life. The purpose is to provide a super hard wood hob.

[0007]

Means for Solving the Problems The present inventor, in order to solve the above-mentioned problems, has found that, as a result of research, a cemented carbide material, which should have better cutting performance than high-speed steel, is vulnerable to impact. Therefore, we thought that the solution would be to increase the number of cutting blades and reduce the maximum impact force applied to the cutting edge of all the blades of the hob. However, in the conventional method of brazing a cemented carbide tip to the mounting portion of the main body of the alloy steel, there is a problem in the strength of the blade and in the discharge of chips, and it has been difficult to increase the number of blade grooves. Therefore, the present inventor has solved the above-mentioned problem by providing a super hard solid hob in which the hob is integrally formed of a super hard material and has 16 to 30 cutting edge grooves, preferably 20 to 24 grooves. .

Since the hob is made of a super hard material and the number of cutting edge grooves is changed from the conventional 10 to 14 grooves to 16 to 30 and the impact at the time of cutting can be reduced, the cutting edge is sharpened ( No rounding, chamfering or negative rake angle) is required. Therefore, it is preferable that the cutting edge is not rounded or chamfered, the rake angle is positive, and the specifications are the same as those of the high-speed steel hob.

[0009]

Embodiments of the present invention will be described. FIG. 1 is a partial side view showing an upper half of a solid carbide hob showing an embodiment of the present invention. As shown in FIG. 1, a superhard material is integrally formed, and a substantially cylindrical main body 1 having an arbor hole 12 provided with a key groove 11 is provided with 22 cutting edges 2 having a rake face on the outer periphery. It is provided equally with the main body together with the cutting groove 3 equally in the shape, and is formed spirally in the axial direction.

Since the hob 1 made of a cemented carbide material has an integral structure, a portion for attaching a cemented carbide tip is not required, and a considerable amount thereof can be allocated to an increase in the number of cutting grooves. As a result, the cutting load per blade is reduced by half, the impact force on the cutting edge 4 is also reduced, and the occurrence of chipping can be suppressed without taking the conventional chipping measures for the carbide cutting blade.

[0011]

Next, an embodiment of a solid carbide hob according to the present invention will be described. The specifications of the gear to be processed are as follows: Module:
5, pressure angle: 17.5 °, number of gears: 68, helix angle: 30 ° left: tooth width: 25mm, material: carburized material, Brinell hardness: HB166, and the various solid carbide hobbs of the present invention used Original, outer diameter: 90mm, total length: 150m
m, hole diameter: 40 mm, number of strips: 3, number of blade grooves: 22 grooves, material is carbide grade P30, and the surface was coated. The processing conditions are as follows: Cutting speed: 320 m / min
(1,132 min ^-1 ), feed: 2.5 mm / rev.
It was done with a climb dry cut.

For comparison, the same gear to be processed was processed by a conventional high-speed steel solid hob. The specifications of the conventional solid high-speed steel hob used are: outer diameter: 97 mm, total length: 150 mm, hole diameter: 40 mm, number of strips: 4, number of blade grooves: 12 grooves, the material is high-speed steel, and the surface is TiN. The coating was applied. The processing conditions were as follows: cutting speed: 1
00 m / min (328 min ^-1 ), feed: 2.5 mm
/ Rev. Cutting was performed by supplying a water-insoluble cutting oil.

As a result, while the conventional high-speed steel hob had a net processing time of 75 seconds, the solid carbide hob of the present invention had a net processing time of 24 seconds and a processing time of 1 / 3. Further, the number of machining steps until re-grinding was 500 for the conventional high-speed steel hob, whereas the solid carbide hob of the present invention could secure a life of 1800, which is more than three times the conventional one. further,
There is little vibration when hobbing.

[0014]

According to the present invention, since the hob is made of a solid carbide material and is made of a solid carbide hob having 16 to 30 cutting edge grooves, the impact at the time of cutting is reduced. While maintaining the characteristics of high-speed cutting, it provides a long-life hob without chipping.

Further, since the number of cutting edge grooves is increased and the impact at the time of cutting is reduced, the cutting edge of the cutting edge does not need to be sharpened (rounded, chamfered or a negative rake angle), and various kinds of materials similar to the high speed steel hob are used. Since the cutting edge is alive, the cutting edge is alive and the sharpness is good and the high heat generation associated with conventional cutting can be suppressed, the service life of the carbide hob is improved, and the effect of dimensional stability of the workpiece is also improved. I was able to get at the same time. In addition, since blade cutting is not required, blade cutting and re-grinding are easy, the work time for re-grinding can be reduced from 4 to 6 hours, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial side view showing an upper half of a solid carbide hob according to an embodiment of the present invention.

FIG. 2 is a partial side view showing the upper half of a conventional high-speed material solid hob.

FIG. 3 is a partial side view showing a cutting blade portion of a conventional carbide hob.

FIG. 4 is a partially enlarged view showing a rounded portion of a cutting edge of a conventional carbide hob.

FIG. 5 is a partially enlarged view showing a chamfered portion of a cutting edge of a conventional carbide hob.

FIG. 6 is a partially enlarged view showing a rake angle of a cutting edge of a conventional carbide hob.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Cutting blade 3 Cutting groove 4 Cutting blade tip

Claims (2)

[Claims] 1. A hob for generating gear teeth, wherein the hob is made of cemented carbide and has 16 cutting grooves.
A solid carbide hob characterized by having up to 30 grooves. 2. There is no rounding or chamfering of the cutting edge,
2. The solid carbide hob according to claim 1, wherein the rake angle is positive.