JPH0623375Y2 - End mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an end mill that imparts rotary motion to cut an outer periphery of a workpiece, a groove, or the like.

[Prior Art] Conventional end mills use high-speed tool steel such as high-speed steel such as high-speed steel and microalloy, and cemented carbide.
This is because when a material having low toughness is used, chipping or chipping occurs at the cutting edge.

In order to prevent such chipping and chipping, it has been proposed to coat the cutting edge with a hard substance such as ceramics, or to perform honing processing on the edge of the cutting edge to be coated (Japanese Patent Laid-Open Publication No. Sho. 60-48211).

[Problems to be Solved by the Invention] However, end mills made of light-velocity tool steel and cemented carbide have short wear due to rapid wear.

Further, a work piece cut by an end mill that is worn out has a problem that the finished surface is poor (the surface roughness is large). It should be noted that this problem of surface roughness has hardly been solved even with an end mill coated with a hard substance.

Therefore, an end mill using a cermet having excellent wear resistance can be considered. However, since cermet has low toughness, even if the cermet having the highest toughness is used, chipping and chipping of the cutting edge occur more frequently than in the case of using cemented carbide. Therefore, the end mill using the cermet has not been realized.

An object of the present invention is to provide an end mill having excellent wear resistance and a beautiful finished surface.

[Means for Solving the Problems] In order to achieve the above object, the end mill of the present invention comprises:
The following technical measures are adopted.

The end mill has an end face cutting edge where the rake face and the bottom blade face intersect, an outer peripheral face cutting edge where the rake face and the outer peripheral face intersect, and a corner portion where the end face cutting edge and the outer peripheral face cutting edge intersect each other. It consists of a cermet. The removal amount in the rake face direction removed by the chamfer is about 0.06 mm, the removal amount in the bottom blade face direction removed by the chamfer is about 0.03 mm, and the outer peripheral surface removed by the chamfer The removal amount in the direction is about 0.03
mm.

[Operation] The cutting edge is chamfered within the scope of the present invention,
The cutting edge strength is improved. Thereby, even if a cermet is used for the end mill, the fracture resistance of the cutting edge is improved.

[Effects of the Invention] As described above, the present invention improves the fracture resistance of the cutting edge, so that the end mill can be formed by a cermet. Therefore, the wear resistance of the end mill can be improved as compared with the conventional one.

Further, since it has excellent wear resistance, it is less likely that cutting will be performed by an end mill that has been worn away as in the conventional case. Therefore, the finished surface becomes more beautiful than the conventional one.

[Embodiment] Next, an end mill of the present invention will be described based on an embodiment shown in the drawings.

(Structure of Embodiment) FIG. 1 is a side view of an end mill, and FIG. 2 is a front view of the end mill.

The end mill 1 shown in this embodiment is a multi-blade end mill having four cutting edges, and is made of a cermet, which is made by sintering and joining a metal such as titanium carbonitride and a ceramic with a combined body.

Each blade of the end mill 1 is provided with a rake face 2 directed in the rotation advancing direction, a bottom blade face 3 serving as an end face of the end mill 1, an outer peripheral face 4 facing the outer periphery, and a back face 5 behind the rake face 2.
An end surface cutting edge 6 is formed at a portion where the rake surface 2 and the bottom blade surface 3 intersect, and an outer peripheral surface cutting edge 7 is formed at a portion where the rake surface 2 and the outer peripheral surface 4 intersect.

The end surface cutting edge 6, the outer peripheral surface cutting edge 7, and the corner portion 8 where the end surface cutting edge 6 and the outer peripheral surface cutting edge 7 intersect are chamfered by the honing process described below. The removal amount by this chamfering is almost the same for both the end face cutting edge 6 and the outer peripheral surface cutting edge 7, and as shown in FIG. 3 and FIG.
The removal amount a removed from the ends of the cutting edges 6 and 7 in the rake face 2 direction is the same as the removal amount b removed in the bottom blade face 3 direction or the removal amount c removed in the outer peripheral face 4 direction. There are also many. Preferably, the removal amount a is the removal amount b and the removal amount c.
It is provided about 1 to 2 times. Specifically, the removal amount a
Is between 0.05 and 0.08 mm, the removal amount b and the removal amount c are
It is provided at about 1/2 of the removal amount a.

Furthermore, the chamfering performed on the end face cutting edge 6, the outer peripheral surface cutting edge 7, and the corner portion 8 is such that the intersecting surfaces (rake surface 2, bottom blade surface 3,
It is continuous with the outer peripheral surface 4) with a smooth curve.

Next, honing processing for chamfering the end mill 1 will be described with reference to FIG.

First, in a plurality of holes 10 formed on the upper surface around the rotating disk body 9, the bottom blade surface 3 faces upward, and at least the end face cutting edge 6 and the outer peripheral surface cutting edge 7 project from the hole 10 in the end mill. 1 and each end mill 1 is installed in each hole 10.
To hold.

Next, an annular brush 11 impregnated with oil mixed with diamond powder is made to cross the upper end portion of each end mill 1 held by the disk body 9 by about 0.1 mm. Then, while rotating the disc body 9, the brush 11 is rotated in a direction different from that of the disc body 9. During this rotation, the brush 11 remains in a state of intersecting the end portion of the end mill 1.

By rotating the disk body 9 and the brush 11 for a predetermined time, the end face cutting edge 6 of the end mill 1, the outer peripheral surface cutting edge 7,
The corner portion 8 is subjected to honing and chamfered in the shape shown in FIGS. 3 and 4.

(Effects of Examples) Next, effects of the present invention will be described based on experimental examples.

The end mills of the present invention (developed product 1) and the end mills used for comparison (comparative products 1, 2, 3, 4, 5) were used for a predetermined time to compare the defect rates. The machining conditions used in the experiment were that the device 1 and the comparative products 1, 2, 3, 4, 5 all had the same shape and the same size (4 blades, diameter 12
mm), the number of revolutions is 3600 rpm, the number of cuts is 3 mm × 3 mm × 36 times per work piece, the feed is 0.1 mm / blade, and the material of the workpiece used for processing is SCr420 (hardness HB180 or so).

Inventive product 1 is made of cermet, and the removal amount a in the rake face direction in chamfering is about 0.06 mm, the removal amount b in the bottom blade face direction is about 0.03 mm, and the removal amount c in the outer peripheral face direction is about 0.
This is a 03 mm end mill 1 (shown in the above embodiment).

Comparative product 1 is an end mill made of cermet and having a removal amount a of about 0.04 mm and removal amounts b and c of about 0.04 mm in chamfering.

Comparative product 2 is an end mill that is made of cermet and has a removal amount a of about 0.06 mm and removal amounts b and c of about 0.06 mm in chamfering.

Comparative product 3 is an end mill made of cermet and not chamfered.

Comparative product 4 is an end mill made of cemented carbide and not chamfered.

Comparative product 5 is made of cemented carbide and has T at the cutting edge.
An end mill that is coated with iN and has a removal amount a of about 0.06 mm in the rake face direction, a removal amount b of about 0.03 mm in the bottom blade face direction, and a removal amount c of about 0.03 mm in the outer peripheral face direction in chamfering. .

Next, the experimental results are shown. Device 1 has a defect rate of 8%, Comparative product 1 has a defect rate of 45%, Comparative product 2 has a defect rate of 12%, Comparative product 3 has a defect rate of 75%, and Comparative products 4 and 5 have a defect rate of 0. %Met. The above contents are shown in Table 1 below.

As can be seen from the above experimental results,
Inventive product 1 having 0.06 mm, removal amount b and removal amount c set to 0.03 mm is superior in fracture resistance to other comparative products and can have a longer life.

Further, FIG. 6 shows a graph showing the relationship between the processing number and the surface roughness (frequency representing the beauty of the finished surface) between the device 1 and the comparative products 4 and 5.

As can be seen from this graph, conventional end mills made of cemented carbide (comparative product 4 → solid line A, comparative product 5 → solid line B)
In the initial stage, the surface roughness is similar to that of the device 1 of the present invention, but since the wear progresses quickly thereafter, the surface roughness increases as the number of machining increases. Then, the surface roughness deteriorates considerably when the number of processed pieces is around 300, which is the time to replace the comparative products 4 and 5. That is, in the conventional end mill, a processed product having a poor finished surface is generated.

However, the end mill 1 of the present invention (device 1 → solid line C)
Even if the number of machining reaches the replacement time of 600, the surface roughness is
Almost no deterioration. Therefore, the end mill 1 of the present invention
A processed product produced by using has an effect that the finished surface is always beautiful.

That is, the end mill 1 of the present invention has a very excellent effect that a beautiful finished surface can be applied to a workpiece for a long period of time.

(Modification) The cermet is preferably made of a material having high toughness such as titanium carbonitride, but a cermet having low toughness may be used to form the end mill.

Although an end mill having four blades is shown, the present invention can be applied regardless of the number of blades.

If there is a portion of the outer peripheral surface cutting edge 7 where the workpiece is not cut, the cutting edge at that portion need not be chamfered.

[Brief description of drawings]

Fig. 1 is a side view of the end mill, Fig. 2 is a front view of the end mill, Fig. 3 is an enlarged sectional view of the end face cutting edge, Fig. 4 is an enlarged sectional view of the outer peripheral cutting edge, and Fig. 5 is a honing machine for the end mill. FIG. 6 is a schematic explanatory view of the main part of FIG. In the figure, 1 ... end mill, 2 ... rake face 3 ... bottom edge face, 4 ... outer peripheral face 6 ... end face cutting edge, 7 ... outer peripheral face cutting edge 8 ... corner part a ... in the rake face direction Amount of removal b …… Amount of removal in the direction of the bottom blade c …… Amount of removal in the direction of the outer peripheral surface

Claims (1)

[Scope of utility model registration request] 1. An end face cutting edge where a rake face and a bottom blade face intersect, an outer peripheral face cutting edge where the rake face and an outer peripheral face intersect, and a corner portion where the end face cutting edge and the outer peripheral face cutting edge intersect, respectively. An end mill comprising a chamfered cermet, wherein the removal amount in the rake face direction removed by the chamfer is about 0.06 mm, and the removal amount in the bottom blade face direction removed by the chamfer is about 0.03 mm, An end mill having a removal amount of about 0.03 mm in the outer peripheral surface direction removed by the chamfering.