CN210548365U

CN210548365U - End milling cutter

Info

Publication number: CN210548365U
Application number: CN201921500182.3U
Authority: CN
Inventors: 王弢; 杨路; 陈刚; 刘健
Original assignee: Suzhou Ahno Precision Cutting Technology Co ltd
Current assignee: Suzhou Ahno Precision Cutting Technology Co ltd
Priority date: 2019-09-10
Filing date: 2019-09-10
Publication date: 2020-05-19
Anticipated expiration: 2029-09-10

Abstract

the utility model relates to an end mill, it is made by zirconia ceramic, including the stalk portion that connects according to the preface, toper transition portion, neck and cutting part, wherein, the cutting part includes two at least excircle sword, all carry out the spiral around the lateral wall of this cutting part and extend, and helix angle α control 25 ~ 42 the week sword anterior angle β control of excircle sword is controlled at 5 ~ 10, week sword posterior angle gamma control is 12 ~ 18, the excircle sword is until extending to the terminal surface of cutting part in order to form the end sword, and its posterior angle delta control is 10 ~ 18 in addition, the external diameter of cutting part is D₁D is 65 to 70% D when the core thickness diameter is D₁. Thus, in the actual cuttingIn the cutting process, the end milling cutter has lower cutting vibration quantity, and the cutting edge is not easy to generate oxidation chemical reaction, thereby effectively ensuring the processing precision and the service life. In addition, the end milling cutter rarely has edge breakage in the specific use process, so that the fineness of the cutting edge is ensured.

Description

End milling cutter

Technical Field

The utility model belongs to the technical field of the cutting tool makes technical field, especially, end milling cutter.

Background

At present, graphite is widely used in the mold manufacturing industry by virtue of its good physical and chemical properties, for example, in the prior art, graphite is used as a material for manufacturing a 3D glass hot bending mold, i.e., graphite is used by virtue of its characteristics of high hardness, good electrical conductivity, radiation resistance, corrosion resistance, good heat conductivity, low cost, high temperature resistance, and the like. However, the following problems are involved in the mechanical forming process of the mold: graphite and metals have opposite properties when heated, specifically: the higher the temperature, the harder the structure. And the graphite has good strength and lower thermal expansion coefficient at high temperature, thereby invisibly increasing the difficulty of machining the die and causing the milling cutters such as the conventional hard alloy and the like to be quickly worn and have short service life. In addition, at present, a hard alloy or diamond coating milling cutter is mainly adopted to carry out a finish machining process, the surface roughness after general forming can only reach Ra0.4 and can not meet the use requirement far away, manual polishing needs to be added subsequently, the labor input is greatly increased, and the production efficiency is reduced. Thus, a skilled person is urgently needed to solve the above problems.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to provide a structural design is simple, and the machining precision is high, and long service life's end mill.

in order to solve the technical problem, the utility model relates to an end mill, it is formed by the grinding of zirconia ceramics, including the stalk portion that connects according to the preface, toper transition portion, neck and cutting part, wherein, cutting part includes two at least excircle sword, all carry out the spiral around the lateral wall of this cutting part and extend, and helix angle α control is at 25 ~ 42₁D is 65 to 70% D when the core thickness diameter is D₁。

As a further improvement of the present invention, the length of the cutting portion is assumed to be L, and then L is 3 to 5D₁。

As the technical scheme of the utility model the further improvement, the radial run-out and the axial run-out of cutting portion are all controlled within 0.005.

According to a further improvement of the present invention, the diameter of the neck is assumed to be D₂Then D is₂Is less than D₁0.1～0.2mm。

Root conduct the utility model discloses technical scheme's further improvement, end milling cutter has still seted up central cooling hole, and it runs through stalk portion, toper transition portion, neck and cutting portion according to the preface.

As a further improvement of the technical proposal of the utility model, the end milling cutter also comprises a reinforcing sleeve which is sleeved and fixed in the central cooling hole. The reinforcing sleeve and the central cooling hole are in interference fit.

Root as the utility model discloses technical scheme's further improvement, around the circumferencial direction of cutting part, each excircle sword is non-equidistance and distributes.

The root is as the utility model discloses technical scheme's further improvement still includes the damping cover, and its cover is located on the lateral wall of stalk portion. The damping sleeve is made of shape memory alloy.

As the utility model discloses technical scheme's further improvement is provided with spacing sand grip at the stalk portion, and its quantity is 2 at least, and carries out the circumference equipartition around the lateral wall of stalk portion, correspondingly, set up the spacing recess with spacing sand grip looks adaptation around the inside wall of damping cover.

Compare in the end mill of traditional design the utility model discloses an among the technical scheme, end mill is made by zirconia ceramic, so, has following advantage in actual mould machine-shaping in-process:

1) the cutting edge has low thermal conductivity, low friction coefficient and low chemical affinity, so that the cutting edge is not easy to generate oxidation chemical reaction, thereby effectively ensuring the processing precision and the service life.

2) The zirconia ceramic end mill has lower fracture toughness, thereby ensuring the fineness of the cutting edge and ensuring the surface roughness after molding.

3) The excircle edge and the end edge of the special design structure effectively reduce the cutting vibration quantity and ensure the processing precision. In addition, the core thickness ratio is improved to a certain extent, and the rigidity of the end mill is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a first embodiment of the neutral milling cutter of the present invention.

Fig. 2 is an enlarged view of a portion I of fig. 1.

Fig. 3 is a partial cross-sectional view of an outer circular edge of a first embodiment of the end mill of the present invention.

Fig. 4 is a partial cross-sectional view of an end blade in a first embodiment of the end mill of the present invention.

Fig. 5 is a left side view of fig. 1.

Fig. 6 is a schematic structural diagram of a neutral milling cutter according to a second embodiment of the present invention.

Fig. 7 is a partial enlarged view II of fig. 6.

Fig. 8 is a schematic structural view of a third embodiment of the neutral milling cutter of the present invention.

3 fig. 3 9 3 is 3 a 3 sectional 3 view 3 a 3- 3 a 3 of 3 fig. 3 8 3. 3

Fig. 10 is a schematic structural view of a fourth embodiment of the neutral milling cutter of the present invention.

Fig. 11 is a sectional view B-B of fig. 10.

1-a handle; 11-limiting convex strips; 2-a conical transition; 3-neck part; 4-a cutting portion; 41-outer circular edge; 42-end edge; 43-a damping surface; 5-central cooling holes; 6-reinforcing sleeve; 7-damping sleeve; 71-limiting groove.

Detailed Description

In the description of the present invention, it is to be understood that the terms "left", "right", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings only for convenience of description of the present invention and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

the present invention will be described in detail with reference to the following embodiments, and fig. 1 shows a schematic structural diagram of a first embodiment of a neutral milling cutter of the present invention, which includes a shank 1, a tapered transition portion 2, a neck 3 and a cutting portion 4, and are connected in sequence from right to left as a whole, wherein the cutting portion 4 includes at least two outer circular blades 41, both extending spirally around the outer side wall of the cutting portion 4, and a helix angle α is controlled to be 25-42 °, a circumferential blade rake angle β of the outer circular blades 41 is controlled to be 5-10 °, a circumferential blade relief angle γ is controlled to be 12-18 °, the outer circular blades 41 extend to the end surface of the cutting portion 4 to form an end blade 42, and the relief angle δ is controlled to be 10-18 ° (as shown in fig. 2, 3 and 4).

In view of the smoothness of the chip removal, in the prior art, the ratio of the core thickness to the cutting part is controlled to be approximately 60%, so that the vibration quantity of the end mill is easily exceeded in the actual machining process, and the final forming precision is further influenced. However, in the process of machining and molding the graphite mold, the graphite cutting chips are crushed, so that the requirement on the size of the chip discharge groove is not high, and the ratio of the core thickness can be increased properly as follows: the outer diameter of the cutting part 4 is assumed to be D₁D is 65 to 70% D when the core thickness diameter is D₁(as shown in fig. 5).

In order to reduce the amount of vibrations during machining, a damping surface 43 (as shown in fig. 2) may also be provided in the transition region between the outer circular edge 41 and the end edge 42. Of course, the outer circular blades 41 may also be distributed in a non-equidistant manner, that is, the angle interval between the outer circular blades 41 around the cutting portion 4 in the circumferential direction has a certain value, so as to effectively avoid the occurrence of resonance phenomenon in the machining process.

In addition, zirconia ceramics have superior physical and chemical properties compared to cemented carbides, as shown in table 1:

TABLE 1

The fracture toughness of the zirconia ceramic is lower than that of the hard alloy, but the friction coefficient is only 1/4-1/5 of that of the hard alloy, so that the chip removal performance of the ceramic milling cutter during high-speed cutting can be improved, the abrasion of the cutter is reduced, and the service life of the cutter is prolonged. In addition, in terms of thermal characteristics, the thermal conductivity of zirconia ceramics is extremely low, and extremely high cutting heat at the time of high-speed cutting is hardly transmitted to the zirconia ceramic cutter body. In addition, since zirconia ceramics have a lower chemical affinity and a sharp and smooth edge than cemented carbide materials, zirconia ceramics are less likely to be oxidized and to be worn by diffusion when graphite materials are machined at high speed, and the tool life is longer.

Table 2 lists the machining conditions and the forming parameters of the conventional cemented carbide tool and the zirconia ceramic end mill disclosed in this embodiment, respectively, and it can be found that the surface roughness of the workpiece machined by the zirconia ceramic end mill is only ra0.1, and it is completely unnecessary to add a manual polishing process, so that the machining efficiency is improved, and the production cost is reduced. On the other hand, the abrasion loss of the zirconia ceramic end mill after processing is lower, and the service life of the cutter is 30-40% longer than that of the diamond coating coated on the hard alloy milling cutter. Fully explain the utility model discloses nonmetal material for the super-finishing whole milling cutter reasonable in design can greatly improve the precision of graphite material processing, reduction in production cost guarantees simultaneously that the cutter life-span obtains further improvement.

TABLE 2

In addition, in order to improve the strength of the end mill in high-speed cutting of graphite and to improve the service life thereof, it is necessary to limit the axial-to-radial ratio of the cutting portion 4, and the following is specifically recommended: assuming that the length of the cutting portion 4 is L, L is 3-5D₁Here, D₁Representing the outer diameter of the cutting portion 4 (as shown in fig. 2).

In order to further improve the machining accuracy of the end mill and to improve the surface roughness of the formed surface, it is also possible to control the total run-out in the radial direction and the total run-out in the axial direction of the cutting portion 4 to be within 0.005, and it is preferable to perform forming by the spark method.

The neck 3 is used for avoiding a workpiece in the actual cutting process, and the diameter of the neck is usually slightly smaller than the outer diameter of the cutting part 4 by 0.1-0.2 mm.

It is known that zirconia ceramics are poor thermal conductors, which are not beneficial to the progress of heat dissipation at the processing position, therefore, fig. 6 shows a schematic structural diagram of a second embodiment of the milling cutter, which is different from the first embodiment: a central cooling hole 5 is formed along the longitudinal direction of the end mill, and sequentially penetrates the shank 1, the tapered transition portion 2, the neck 3, and the cutting portion 4. The central cooling hole 5 extends up to the end edge 42 and is fed with a low temperature inert gas (e.g. nitrogen, etc.) to form an air cooling port (as shown in fig. 7). In addition, as a further optimization of the above technical solution, independent air cooling ports are provided on each of the end blades 42.

Fig. 8 shows a schematic structural diagram of a third embodiment of the neutral milling cutter of the present invention, which is different from the second embodiment in that: a reinforcing sleeve 6 (shown in fig. 9) is fitted inside the central cooling hole 5 to offset the weakening of the structural strength of the end mill itself by machining the central cooling hole 5. Generally, the reinforcing sleeve 6 is preferably made of a metal having a high tensile strength and a high yield strength, and is preferably assembled with the central cooling hole 5 in an interference fit manner. In actual operation, the reinforcing sleeve 6 can be placed into liquid nitrogen in advance for extreme cooling, and then inserted into the central cooling hole 5 to be restored to normal temperature.

Fig. 10 shows a schematic structural diagram of a fourth embodiment of the neutral milling cutter of the present invention, which is different from the third embodiment in that: the outer side wall of the handle part 1 is sleeved and fixed with a damping sleeve 7. It should be noted that the damping sleeve 7 is made of a shape memory alloy. Shape memory alloys are known to have the following characteristics: the shape memory effect of shape memory alloys results from a thermoelastic martensitic transformation, which, once formed, continues to grow as the temperature decreases and, if the temperature increases, decreases, disappearing in the exact opposite process. The difference between the two free energies is used as the driving force for phase transition. The temperature T0 at which the two free energies are equal is called the equilibrium temperature. The martensitic transformation occurs only when the temperature is below the equilibrium temperature T0, whereas the reverse transformation occurs only when the temperature is above the equilibrium temperature T0. In the shape memory alloy, martensite phase transformation is not only caused by temperature but also caused by stress, the martensite phase transformation caused by the stress is called stress-induced martensite phase transformation, and the transformation temperature and the stress are in a linear relation, so that the deformation phenomenon that the mechanical force action and the related crystal phase transformation are reversible and lagged on the prestress of the martensite phase transformation occur, the mechanical energy is dissipated, and the vibration quantity of the end mill in the actual machining process is reduced.

Of course, as a further optimization of the above technical solution, the shank 1 may be further provided with at least 2 limiting convex strips 11, and the limiting convex strips are circumferentially and uniformly distributed around the outer side wall of the shank 1, and correspondingly, limiting grooves 71 (as shown in fig. 11) adapted to the limiting convex strips 11 are formed around the inner side wall of the damping sleeve 7, so as to ensure that deformation amounts of regions around the circumference of the damping sleeve 7 tend to be consistent as much as possible, thereby ensuring that the end mill has good vibration resistance.

Finally, as a further optimization of the above technical solution, the cross section of the limiting convex strip may be designed to be a trapezoid with a small top and a large bottom (as shown in fig. 11) in view of the convenience of assembling the damping sleeve 7.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. an end mill is characterized in that the end mill is formed by grinding zirconia ceramics and comprises a handle part, a conical transition part, a neck part and a cutting part which are connected in sequence, wherein the cutting part comprises at least two outer circular cutting edges, each outer circular cutting edge spirally extends around the outer side wall of the cutting part, the helix angle α is 25-42 degrees, the peripheral cutting edge front angle β of each outer circular cutting edge is 5-10 degrees, the peripheral cutting edge rear angle gamma is 12-18 degrees, the outer circular cutting edges extend to the end face of the cutting part to form end cutting edges, the rear angle delta is 10-18 degrees, and the outer diameter D of the cutting part is D₁D is 65 to 70% D when the core thickness diameter is D₁。

2. The end mill according to claim 1, wherein the length of the cutting portion is L, and L is 3-5D₁。

3. The end mill according to claim 2, wherein the cutting portion has a full radial run out and a full axial run out both controlled to within 0.005.

4. The end mill according to claim 1, characterized in that the neck diameter is D₂Then D is₂Is less than D₁0.1～0.2mm。

5. The end mill according to any one of claims 1-4, further comprising a central cooling hole extending through the shank portion, the tapered transition portion, the neck portion, and the cutting portion in that order.

6. The end mill according to claim 5, further comprising a reinforcing sleeve disposed over and secured within the central cooling bore; and the reinforcing sleeve and the central cooling hole are in interference fit.

7. The end mill according to any one of claims 1-4, wherein the outer circular edges are distributed non-equidistantly around the circumference of the cutting portion.

8. The end mill according to any one of claims 1-4, further comprising a damping sleeve fitted over an outer side wall of the shank; the damping sleeve is made of shape memory alloy.

9. The end mill according to claim 8, wherein the shank portion is provided with a plurality of limiting ribs, the number of the limiting ribs is at least 2, the limiting ribs are circumferentially and uniformly distributed around the outer side wall of the shank portion, and correspondingly, limiting grooves matched with the limiting ribs are formed around the inner side wall of the damping sleeve.