JP2001087929A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill having a small diameter as much as practicable whereby it is possible for its cutting head side to be fastened to the shank very strongly and with good accuracy about the axial and radial directions. SOLUTION: An end mill is composed of a body 3 including a cutting head 1 and a shaft for coupling 2 and a shank 4 to be coupled with the body 3 removably, wherein the shank 4 has a hollow part 10 fitted with a fastening rod 13 having a male threaded portion 12, and a female threaded portion 7 in the shaft 2 is fitted on the male threaded portion 12 of the rod 13, and thereby a fit-in shaft part 6 of the shaft 2 is fitted in a fit-in hole 5 provided in the shank 4, and the peripheral surface 6a of the fit-in shaft part 6 is abutted to the inside surface 5a of the hole 5 and also the end face 8 of the shank 4 is abutted to the abutting surface 9 of the shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill, and more particularly to a so-called throw-away type end mill in which a cutting head provided with a blade portion can be replaced with a shank supporting the cutting head.

[0002]

2. Description of the Related Art A so-called solid type end mill in which a cutting head is fixed to the tip of a shank requires a high cost of re-polishing and a problem with re-polishing accuracy when damaged. Despite such defects, the entire tool must be discarded, and in particular, a solid end mill made of a super-hard alloy is expensive and therefore very uneconomical. Instead of such a solid type end mill, a so-called throw-away type end mill has been proposed in which a cutting head can be replaced with a shank.

[0003] Examples of conventional throw-away type end mills include those described in, for example, JP-A-4-256512 and JP-A-58-164617. The former end mill is provided with a center mounting hole penetrating in the axial direction at one end of a bar-shaped shank, and receives the small shaft portion of the cutting head via a tapered collet at the distal end side of the mounting hole, and centers the tapered collet. By towing with the traction bolt located in the mounting hole,
The cutting head is fixed to the tip of the shank. In the latter end mill, a conical projection or recess is formed at the tip of the shank, and a recess or projection to which the projection or recess is engageable is formed on the rear end face side of the cutting head, and at the center of the shaft. The cutting head is fixed to the shank by forming a through hole and screwing a bolt from the front side of the cutting head into the tip end of the shank through the through hole and tightening.

In the former end mill described in Japanese Patent Application Laid-Open No. 4-256512, a configuration is employed in which the small shaft portion of the cutting head is gripped and fixed by a taper collet. Outer diameter is 20mm
It is technically very difficult to manufacture a small diameter end mill of the following order, and the cost is very high. Further, in the latter end mill described in Japanese Utility Model Application Laid-Open No. 58-164617, a bolt is inserted from the front side of the cutting head and the head is attached to the tip of the shank, and cutting is performed in the central region of the tip of the cutting head. Can not.

In order to solve the above two problems, the applicant of the present invention can manufacture an end mill having an outer diameter as small as 20 mm or less as disclosed in Japanese Patent Application Laid-Open No. Hei 10-249627, and furthermore, a cutting head side. An end mill has been proposed which can be accurately and extremely firmly mounted and fixed to the shank in the axial and radial directions, but this latest prior art is also similar to the above-mentioned Japanese Patent Application Laid-Open No. 4-256512. Since the pulling bolt is provided and the pulling bolt is operated from the rear end of the shank, the operation is slightly troublesome. Especially, the pulling bolt is formed to be long by inserting it through the entire area of the shank. When the cutting head is pulled into the shank side by the pulling force of the long pulling bolt and connected therewith, the bolt is Extends is occurred, this was a disadvantage that coupling strength because insufficient.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an end mill having an outer diameter as small as 20 mm or less can be manufactured by solving the above-mentioned difficulties, and the cutting head side can be axially and radially moved with respect to the shank. It is an object of the present invention to provide a throw-away type end mill of this kind which can be attached and fixed with high precision and extremely firmly, and can firmly connect a cutting rod to a shank.

[0007]

The end mill according to the first aspect of the present invention is provided with a connecting shaft 2 at the rear portion of the cutting head 1 as shown in FIG. An end mill main body 3 formed integrally and a shank 4 detachably connected to the end mill main body 3, and the connecting shaft 2 is provided with a shank 4.
The shank 4 has a fitting shaft portion 6 fitted into the fitting hole portion 5, a screw portion 7 provided concentrically with the shaft portion 6, and a contact surface 9 contacting the end surface 8 of the shank 4. The hollow portion 10 has a tightening rod 13, and the screw portion 7 of the connecting shaft 2 is connected to the tightening rod 1.
3, the fitting shaft 6 of the connecting shaft 2 fits into the fitting hole 5 of the shank 4, and the outer peripheral surface 6a of the fitting shaft 6 and the shank 4 are screwed. Fitting hole 5
And the end surface 8a of the end mill body 3 is connected to the shank 4 while the end surface 8 of the shank 4 and the contact surface 9 of the connecting shaft 2 are in contact with each other. is there.

The end mill according to the invention according to claim 2 is:
The inner peripheral surface (5a) of the fitting hole (5) of the shank (4) and the outer peripheral surface (6a) of the fitting shaft (6) of the connecting shaft (2) fitted into the shank (4) are formed as tapered surfaces. It consists of a structure of.

The end mill according to the third aspect of the present invention comprises:
A slight gap α is provided between the inner peripheral surface 10a of the hollow portion 10 of the shank 4 and the outer peripheral surface 11a of the tightening rod 13 fitted thereto, and a pin insertion provided on the tightening rod 13 is provided. Opposite surface between the inner peripheral surface 14a of the hole 14 and the outer peripheral surface 16a of the support pin 16 to be inserted therein, or opposition between the outer peripheral surface 16a of the support pin 16 and the inner peripheral surface 15a of the pin receiving hole 15 provided in the shank 4. A slight gap β in any of the opposing surfaces
The configuration according to claim 1 or 2 is provided.

According to a fourth aspect of the present invention, the tightening rod 13 has a hollow portion 20 penetrating in the axial direction.

[0011]

FIG. 1 shows a half cross section of an entire embodiment of the present invention, which comprises an end mill body 3 at a tip and a shank 4 detachably connected thereto. Is 91.7 mm, and an example of the cutting diameter D of the end mill body 3 is 8 mm.

The shank 4 is formed in the hollow portion 10 over the entire area in the axial direction, and the fitting hole 5 of the end mill main body 3 is formed at the tip thereof.

FIG. 2 is an enlarged view of the tip portion of FIG. 1, and FIG. 3 is an exploded view of each component.

The end mill body 3 includes a cutting head 1 having a ball-like appearance and a connecting shaft 2 integrally attached to the rear portion of the head 1 by brazing or the like. The cutting head 1 and the connecting shaft 2 may be integrally formed. The connecting shaft 2 includes a main body 17 having substantially the same diameter as the cutting head 1, a fitting shaft 6 protruding concentrically from the main body 17, and a female screw 7 provided at the shaft center of the shaft. And a contact surface 9 described later provided at a boundary portion between the fitting shaft portion 6 and the main body portion 17. An oil supply hole 18 extends radially outward from the cutting head 1 to the connecting shaft 2.

The shank 4 has a fitting hole 5 into which a fitting shaft 6 of the connecting shaft 2 is fitted at an end thereof, and an end surface 8 which is in contact with a contact surface 9 of the connecting shaft 2. In the hollow portion 10 of the shank 4, a tightening rod 13 and a radial support pin 16 for supporting the tightening rod 13 on the shank 4 are provided.

That is, the tightening rod 13 is composed of a rod portion 11 fitted to the hollow portion 10 of the shank 4 and the rod portion 11.
The support pin 16 is inserted into a pin insertion hole 14 penetrating the rod portion 11 in the radial direction, and is coaxial with the pin insertion hole 14. The pin 13 is received by a pin receiving hole 15 penetrating the shank 4, whereby the tightening rod 13 is supported by the shank 4 by the support pin 16. As shown in FIG. 3, a tool mounting surface 19 for screwing the end mill main body 3 into the shank 4 is formed on the main body portion 17 of the connecting shaft body 2 in the end mill main body 3.

While the fitting shaft 6 of the connecting shaft 2 in the end mill body 3 is fitted in the fitting hole 5 of the shank 4, the female screw 7 is fitted to the male thread 12 of the tightening rod 13. As the screw is screwed in, the fitting shaft 6 of the connecting shaft 2 is guided and fitted into the fitting hole 5 of the shank 4, and at the fitting end position, the inner peripheral surface 5a of the fitting hole 5 of the shank 4. The outer peripheral surface 6a of the fitting shaft portion 6 of the connecting shaft 2 comes into contact with the end surface 8 of the connecting shaft 2 with the end surface 8 of the shank 4, so that the end mill body 3 is formed by so-called two-plane restraint. Will be connected to the shank 4 in an accurately positioned state.

According to the present invention, since the end mill body 3 is screwed and connected from the tip end side of the shank 4, the connection work, that is, the replacement work of the throw-away type end mill body 3 can be easily performed. Can be.

The cutting head 1 is connected to the shank 4 by providing a tightening rod 13 only at the tip of the shank 4 and screwing the female screw 7 of the connecting shaft 2 into the male screw 12 provided on the rod 13. As a result, the length of the tightening rod 13 can be reduced, and there is no fear of a decrease in tightening rigidity due to the extension of the tightening rod unlike the related art, so that the connecting rigidity can be significantly increased.

According to another embodiment of the present invention, claim 2 is provided.
As described in the above, the inner peripheral surface 5a of the fitting hole 5 of the shank 4
And the outer peripheral surface 6a of the fitting shaft portion 6 of the connecting shaft body 2 fitted thereto are formed as tapered surfaces, so that there is an effect of increasing the connection strength and concentricity by the wedge effect.

In order to accurately maintain the straightness of the end mill, the shank 4 and the cutting head 1 connected to the tip must be formed exactly concentrically. If the female thread 7 of the connecting shaft 2 on the cutting head 1 side and the tightening rod 13 on the shank 4 side
If one or both of the male screw portions 12 are not formed exactly concentrically, the screwing of the two causes a distortion that is displaced from the axial direction between the shank 4 and the cutting head 1, and the two are accurately removed. They cannot be connected concentrically.

In order to solve the problem, in the embodiment of the present invention, the tightening rod 13 on the male screw portion 12 is supported in the shank 4 in a floating state in the radial direction and the axial direction. That is, as described in claim 3, the shank 4
A slight gap α in micron units is provided between the inner peripheral surface 10a of the hollow portion 10 and the outer peripheral surface 11a of the tightening rod 13 fitted thereto, and a pin fitting provided on the tightening rod 13 is provided. A surface facing the inner peripheral surface 14a of the insertion hole 14 and the outer peripheral surface 16a of the support pin 16 fitted therein or the support pin 16
In the same manner, a slight gap β in micron units is provided on any of the opposing surfaces of the outer peripheral surface 16a and the inner peripheral surface 15a of the pin receiving hole 15 provided in the shank 4.

For this reason, even if one or both of the female thread 7 of the connecting shaft 2 on the cutting head 1 side and the male thread 12 of the fastening rod 13 on the shank 4 are slightly concentric with each other. Even if it is displaced, the tightening rod 13 will be screwed in a floating state in a direction to correct the deviation, and as a result, the shank 4 and the cutting head 1 will be accurately and concentrically connected. Become.

Further, in the embodiment of the present invention, the tightening rod 13 has an oil passage 20 penetrating in the axial direction, and the hollow portion 10 of the shank 4 and the oil supply passage of the cutting head 1. 18 and is characterized in that cutting oil is jetted from these oil passages to the processing surface during the processing operation. Even in the prior art, there is a fastening rod in which a hollow portion for an oil passage is formed in the entire area in the axial direction, but in the prior art, the fastening rod is a long one extending over the entire length of the shank. Therefore, when the hollow portion is provided in the long tightening rod, the tightening rod becomes thinner accordingly, the resistance to elongation at the time of tightening is reduced, and the connection rigidity is further reduced. In the embodiment, since the length of the fastening rod 13 can be very short, even if the fastening rod 13 is provided with the hollow portion 20 which is a passage,
The extension at the time of tightening can be neglected, and does not affect the connection strength.

As described above, according to the present invention, the fitting shaft 6 on the connecting shaft 2 and the fitting hole 5 on the shank 4 are fitted to each other, and the inner and outer surfaces 6a, 5a are in contact with each other, and the contact surface 9 on the connecting shaft 2 side and the end surface 8 on the shank 4 side are pressed against each other, so that the end mill body 3 and the shank 4 are axially and radially restricted. As a result, the two components are coaxially coupled with high precision, and the mounting accuracy is improved. In addition, the connecting shaft 2 and the shank 4
Is directly tightened by screwing the female screw portion 7 on the connecting shaft 2 side with the male screw portion 12 of the tightening rod 13 on the shank 4 side, so that the end mill body 3 and the shank 4 are extremely firmly connected. It becomes a rigid body by being fixed, so that the cutting accuracy when using the end mill can be enhanced. As described above, the connection structure of the end mill includes a fitting structure of the fitting shaft portion 6 and the fitting hole portion 5, a screwing structure of the female screw portion 7 and the male screw portion 12, and a connecting shaft 2 Since the axially and radially abutting surfaces of the shaft side and the shank 4 side are in contact with each other, the structure is extremely simple.
It is possible to easily manufacture a small-diameter end mill having a diameter of less than 1 mm.

[0026]

According to the end mill of the first aspect of the present invention, the fitting shaft portion of the connecting shaft body in the end mill body is fitted into the fitting hole of the shank, and the female screw portion of the tightening rod is fitted. As the screw is screwed into the male thread, the fitting shaft of the connecting shaft is guided and fitted into the fitting hole of the shank, and at the fitting end position, the connecting shaft is fitted on the inner peripheral surface of the fitting hole of the shank. The end surface of the end mill main body can be firmly connected to the shank by so-called two-sided restraint, while the outer peripheral surface of the fitting shaft portion of the body abuts and the abutment surface of the connecting shaft abuts the end surface of the shank.

Further, the connecting shaft and the shank are directly tightened by screwing the female screw on the connecting shaft and the male screw of the tightening rod on the shank. It is extremely rigidly connected and fixed to form a rigid body, and therefore, the cutting accuracy when the end mill is used can be improved. Further, as described above, the connection structure of the end mill includes a fitting structure of the fitting shaft portion and the fitting hole portion, a screwing structure of the female screw portion and the male screw portion, and a connection shaft side and a shank side. Since the structure in which both the axial and radial contact surfaces are in contact with each other is extremely simple, it is possible to easily manufacture a small-diameter end mill having an outer diameter of 20 mm or less.

Furthermore, according to the present invention, since the end mill body is screwed and connected from the tip end side of the shank, the work of attaching and detaching the end mill body, that is, the work of replacing the throw-away type end mill body can be easily performed. it can.

Further, a fastening rod is provided only at the tip of the shank, and the cutting head is connected to the shank by screwing the female thread of the connecting shaft into the male thread provided on the rod. The length of the tightening rod can be shortened, and there is no concern that the tightening rigidity is reduced due to the extension of the tightening rod as in the related art, and the connection rigidity can be significantly increased.

Since the shank and the tightening rod are separate bodies, for example, the shank can be formed of a super-hard material, and a highly rigid end mill can be manufactured.

According to the end mill according to the second aspect of the present invention, the inner peripheral surface of the fitting hole of the shank and the outer peripheral surface of the fitting shaft of the connecting shaft fitted into the shank are tapered from each other. Since it is formed on the surface, there is an effect of increasing the connection strength and concentricity by the wedge effect. That is, the outer peripheral surface of the taper fitting shaft portion and the inner peripheral surface of the taper fitting hole portion are almost completely in close contact with each other, and the coupling rigidity between the two is further increased, and the mounting accuracy between the end mill body and the shank is further improved. become.

According to the third aspect of the present invention, a slight gap is provided between the inner peripheral surface of the hollow portion of the shank and the outer peripheral surface of the tightening rod fitted therein, and a tightening operation is performed. The opposite surface between the inner peripheral surface of the pin insertion hole provided in the rod and the outer peripheral surface of the support pin inserted into the rod, or the opposite surface of the outer peripheral surface of the support pin and the inner peripheral surface of the pin receiving hole provided in the shank. A slight gap is provided on either of the opposing surfaces to support the tightening rod on the male screw portion in a floating state in the radial direction and the axial direction in the shank. Even if the concentric position of one or both of the internal thread and the external thread of the shank side fastening rod is slightly shifted, the fastening rod is screwed in a floating state in the direction to correct the shift. The shank and cutting It will be correctly connected to the concentric to the de.

According to the end mill of the present invention, the tightening rod has an oil passage which penetrates in the axial direction, is connected to the hollow portion of the shank and the oil supply passage of the cutting head, and is used during machining. Since the cutting oil is injected and supplied from these oil passages to the processing surface, it is possible to improve the processing efficiency.

Further, even in the prior art, there is a fastening rod in which a hollow portion for an oil passage is formed in the entire axial direction of the fastening rod, but in the prior art, the fastening rod has a length extending over the entire length of the shank. Since the hollow portion was provided in the long tightening rod, the tightening rod became thinner accordingly,
Although the resistance to the elongation at the time of the tightening is reduced and the connection rigidity is further reduced, in the present invention, since the length of the tightening rod can be very short, even if the tightening rod is provided with a passageway. Even if a certain hollow portion is provided, the extension at the time of tightening can be ignored, and the connection strength is not affected.

[Brief description of the drawings]

FIG. 1 is a half sectional front view showing an entire embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional front view of the essential part.

FIG. 3 is an exploded perspective view of the main part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutting head 2 Connecting shaft 3 End mill main body 4 Shank 5 Fitting hole 5a Inner peripheral surface of fitting hole 5 6 Fitting shaft 6a Outer peripheral surface of fitting shaft 6 7 Female thread 8 End surface 9 Contact Surface 10 Hollow portion 10a Inner peripheral surface of hollow portion 10 11 Rod portion 11a Outer peripheral surface of rod portion 12 Male screw portion 13 Tightening rod 13a Hollow portion of tightening rod 13 14 Pin fitting hole 14a Pin fitting hole 14 Peripheral surface 15 Pin receiving hole 15a Inner peripheral surface of pin receiving hole 15 16 Support pin 16a Outer peripheral surface of support pin 16

Claims (4)

[Claims] An end mill body having a connecting shaft integrally or integrally formed at a rear portion of a cutting head;
The shank is detachably connected to the end mill main body, and the connecting shaft body includes a fitting shaft portion fitted in a fitting hole portion of the shank, a screw portion provided concentrically with the shaft portion, and a shank. The shank has a fastening rod supported by a support pin in a hollow portion of the shank, and has a threaded portion of the connecting shaft body provided concentrically with the fastening rod. The fitting shaft of the connecting shaft fits into the fitting hole of the shank, and the outer peripheral surface of the fitting shaft and the inner peripheral surface of the fitting hole of the shank contact each other. In addition, an end mill in which an end face of the end mill body is connected to the shank by contacting an end face of the shank and a contact surface of the connecting shaft body with each other. 2. The shank according to claim 1, wherein the inner peripheral surface of the fitting hole of the shank and the outer peripheral surface of the fitting shaft of the connecting shaft fitted into the shank are tapered from each other. End mill. 3. A small gap is provided between the inner peripheral surface of the hollow portion of the shank and the outer peripheral surface of the tightening rod fitted therein, and a pin fitting hole provided in the tightening rod is provided. Some of the opposing surfaces of the inner peripheral surface and the outer peripheral surface of the support pin to be inserted into the inner peripheral surface or the inner peripheral surface of the outer peripheral surface of the support pin and the inner peripheral surface of the pin receiving hole provided in the shank may be slightly different. 3. The end mill according to claim 1, wherein a gap is provided. 4. The end mill according to claim 1, wherein the tightening rod has an oil passage that penetrates in an axial direction.