WO2009157606A1

WO2009157606A1 - Adjustable double head cutting tool

Info

Publication number: WO2009157606A1
Application number: PCT/KR2008/003906
Authority: WO
Inventors: Chul-Ho Lee
Original assignee: Taegutec. Ltd.
Priority date: 2008-06-26
Filing date: 2008-07-02
Publication date: 2009-12-30
Also published as: KR100982788B1; KR20100001098A

Abstract

A cutting tool assembly according to the present disclosure comprises a cutting tool and a tool holder, wherein the cutting tool comprises two cutting heads each provided with a cutting edge or a cutting insert pocket and a shank extending between the two cutting heads. The shank is provided with a chip flute formed on an outer peripheral surface thereof. The tool holder is comprised of a housing and a limit screw. The housing is provided with a socket extending axially inward from the front end surface for receiving the cutting tool and is provided with an internally-threaded axial hole extending axially inward from the rear end surface and communicating with the socket. The socket is provided with an internal ledge extending axially on inner wall thereof, and the limit screw is threaded into the internally-threaded axial hole. The cutting tool of the present disclosure has an extended service life and reduced vibrations.

Description

Description ADJUSTABLE DOUBLE HEAD CUTTING TOOL

Technical Field

[1] The technology described herein relates generally to cutting tools, and more particularly to a double head cutting tool, a tool holder, and a cutting tool assembly wherein the cutting tool is adjustably combined with the tool holder.

[2]

Background Art

[3] In conventional cutting tools, only one head is available for machining a cylindrical work-piece. When conventional tools are combined in a tool holder, the maximum depth of cut is fixed. Therefore, since the overhang of the tool is often unnecessarily long, even in cases with a small cutting depth, the tools are vulnerable to vibration because of the long overhang. In addition, conventional cutting tools have a cylindrical shank and the radial angle of the cutting edge of the tools should be carefully aligned when the tools are inserted in the socket of a tool holder.

[4]

Disclosure of Invention Technical Problem

[5] The cutting tools according to the various embodiments of the present disclosure are part of a tool assembly which is easy to assemble, has an adjustable hangover, and has a service life double that of conventional cutting tools.

[6]

Technical Solution

[7] A cutting tool assembly according to the present disclosure comprises a cutting tool and a tool holder, wherein the cutting tool has two cutting heads, each provided with a cutting edge or a cutting insert pocket and a shank extending between the two cutting heads. The shank is provided with a chip flute formed on the outer peripheral surface thereof so that the shank has a transversal cross section of a partial circle. The chip flute is formed by a pair of internal surfaces facing each other, and a cutting edge or cutting insert pocket is formed on the side of one internal surface at one cutting head while another cutting edge or cutting insert pocket is formed on the side of the other internal surface at the other cutting head. The tool holder is comprised of a housing and a limit screw, the housing being provided with a socket extending axially inwardly from the front end surface for receiving the cutting tool and provided with a internally- threaded axial hole extending axially inwardly from the rear end surface and communicating with the socket, wherein the socket is provided with an internal ledge extending axially on inner wall thereof such that the internal ledge is shaped to fit snugly into the chip flute of the cutting tool, and the limit screw threaded into the internally-threaded axial hole.

Advantageous Effects

[8] Since the cutting tool according to the present invention has two cutting heads which could be used in turn, the service life of the cutting tool could be doubled compared to that of a conventional tool with a single cutting head. [9] The cutting tool assembly according to the present invention has an adjustable plug to define the depth to which the cutting tool can be inserted into the socket. This allows the overhang of the cutting tool to be minimized in the case of a small cutting depth in a work piece so as to reduce vibrations. [10] The cutting tool assembly according to the present invention has an engagement structure by which the driving torque of the tool holder is delivered to the cutting tool.

This also allows easy alignment of the relative radial angle between the cutting tool and the tool holder. [11] The cutting tool assembly according to the present invention has an internal flow path through which a coolant is supplied to the cutting edge. [12]

Brief Description of the Drawings [13] FIG. 1 is a perspective view of one embodiment of a cutting tool according to the present invention, with the tool holder housing shown in phantom. [14] FIG. 2 is a perspective view of another embodiment of a cutting tool according to the present invention. [15] FIG. 3 is an exploded perspective view of one embodiment of a cutting tool assembly according to the present invention. [16] FIG. 4 is a partial cross sectional view showing an embodiment of the cutting tool assembly fully assembled according to the present invention. [17] FIG. 5 is a partial cross sectional view showing an embodiment of the cutting tool assembly comprising a back adaptor. [18] FIG. 6 is a perspective view showing an embodiment of the back adaptor and the limit screw. [19] FIG. 7 is a side view showing an embodiment of the back adaptor interposed between the cutting tool and the limit screw.

[20] FIG. 8 illustrates an embodiment of the coolant channel within the cutting tool.

[21] FIG. 9 illustrates another embodiment of the cutting tool assembly according to the present invention. Best Mode for Carrying Out the Invention

[23] Hereinafter, a cutting tool and a cutting tool assembly comprising the same according to an example embodiment of the present disclosure are described. The figures attached to the present disclosure are for the convenience of explanation and the shapes and the relative scales may be exaggerated or abridged.

[24] A cutting tool assembly 900 comprises a cutting tool 100 secured in a tool holder

200.

[25] FIG. 1 is a perspective view of one embodiment of a cutting tool according to the present invention, with the tool holder housing 210 shown in phantom.

[26] The cutting tool 100 shown in FIG. 1 comprises two cutting heads 110, 120 each provided with a cutting edge 112, 122 and a shank 130 extending between the two cutting heads 110, 120. The shank 130 has a rotational axis S therethrough and is provided with a chip flute 140 formed on the outer peripheral surface 132 thereof so that the shank has an approximately three-quarter circular transversal cross section. The transversal cross section of the shank may be a partial circle which is greater or less than three-quarters of a circle.

[27] The chip flute 140 may be generally formed by approximately symmetric a pair of internal surfaces 141, 142 of an arbitrary shape facing each other, and the internal surfaces may be curved surfaces. FIG. 1 shows an example of a chip flute 140 formed by two radial plane surfaces 141, 142 intersecting at the rotational axis S and facing each other at a right angle, so that the chip flute makes a v-shaped groove.

[28] A cutting edge 112 is formed on the side of one internal surface 141 at one cutting head 110 and another cutting edge 122 is formed on the side of the other internal surface 142 at the other cutting head 120.

[29] FIG. 2 is a perspective view of another embodiment of a cutting tool according to the present invention. The cutting tool of FIG. 2 is provided with cutting insert pockets 115, 117 instead of cutting edges on both cutting heads 110, 120. A cutting insert 113 may be mounted in one of the pockets 115,117. The cutting tool of FIG. 2 is usually called an indexing type, while the cutting tool of FIG. 1 is called a solid type. Generally, the indexing type cutting tool with insert pockets has a larger diameter than the solid type cutting tool. The cutting head 120 not mounted with a cutting insert is inserted in the socket of a tool holder in a cutting tool assembly, which is described hereinafter.

[30] Since the cutting tool according to the present invention has two cutting heads which could be used in turn, the service life of the cutting tool could be doubled compared to a tool with a single cutting head.

[31] The cutting tool 100 is secured in a tool holder 200 comprising a housing 210 and a limit screw 400, making a cutting tool assembly 900. The tool holder 200 may further comprise one or more side set screws 500 to be threaded into the tool holder housing 210.

[32] FIG. 3 is an exploded perspective view of one embodiment of a cutting tool assembly

900 according to the present invention. FIG. 4 is a partial cross sectional view, showing an embodiment of the cutting tool assembly fully assembled according to the present invention. The cross section of FIG. 4 is cut through the rotational axis S and the internal ledge 230.

[33] The housing 210 is provided with a socket 220 extending axially inward from the front end surface 221 for receiving the cutting tool, and is also provided with an internally-threaded axial hole 240 extending axially inward from the rear end surface 241. The socket 220 and the internally-threaded axial hole 240 communicate with each other in a longitudinally aligned manner. The socket is provided with an internal ledge 230 extending axially on the inner wall thereof such that the internal ledge is shaped to fit snugly into the chip flute 140 of the cutting tool. The maximum diameter of the socket 220 is preferably smaller than the diameter of the internally-threaded axial hole 240.

[34] As shown in FIGs. 3 and 4, the cutting tool 100 is assembled with the tool holder 200 by inserting one head 120 of the cutting tool 100 into the socket of the tool holder housing 210 until it makes contact with the tip of the limit screw 400 which is threaded into the internally-threaded axial hole 240. The limit screw 400 functions as an adjustable plug to define the depth to which the cutting tool 100 can be inserted into the socket 220. This function allows minimal overhang (protruded distance) of the cutting tool in the case of a small cutting depth in a work piece so as to reduce vibrations. The head end of the limit screw 400 has a hexagonal recess into which the end of a hexagonal wrench can be inserted to turn the screw when it is necessary to change the overhang of the cutting tool. The hexagonal recess may be replaced with a straight or cross form of driver groove.

[35] When the cutting tool 100 is guided into the socket 220, the chip flute 140 of the cutting tool 100 engages with the internal ledge 230. This engagement between the chip flute 140 and the internal ledge 230 prevents the independent rotation of the cutting tool 100 within the socket of the tool holder 200. Therefore, the driving torque of the tool holder 200 can be delivered to the cutting tool 100 by this engagement structure therebetween without additional clamping means. Also, when the cutting tool is coupled to the tool holder, the chip flute 140 of the cutting tool is guided by the internal ledge 230 of the tool holder housing. This allows easy alignment of the relative radial angle between the cutting tool and the tool holder.

[36] The tool holder housing 210 may also be provided with one or more threaded radial through holes 250 extending through the side wall of the housing at a radial position opposite to the internal ledge 230 and communicating with the socket. In this case, the tool holder 200 further comprises one or more side set screws 500 threaded into the threaded radial through hole 250. The side set screw 500 is turned down until it seats firmly against the outer peripheral surface 132 of the cutting tool. The secure seating of the side set screw 500 against the outer peripheral surface 132 holds the cutting tool 100 firmly inside tool holder 200, preventing axial movement of the cutting tool 100 out of the socket of the tool holder.

[37] The cutting tool assembly 900 may further comprise a back adaptor 300 as shown in

FIG. 5. The back adaptor 300 is cylindrically-shaped with a substantially partially- circular (Lg., three-quarter) cross section, which corresponds to that of the shank of the cutting tool, and preferably extends axially over the region between the socket 220 and the internally-threaded axial hole 240 so that the back adaptor is received at least partly inside the socket 220. FIG. 6 shows a perspective view of an embodiment of the back adaptor. The back adaptor is interposed between the cutting tool 100 and the limit screw 400 to prevent direct contact therebetween. The back adaptor is especially useful for the solid type cutting tool which has cutting edges on both heads as shown in FIG. 1, because direct contact between the cutting tool 100 and the limit screw 400 may cause damage to the support surface of the limit screw 400 as well as the cutting edge of the cutting tool 100. Therefore, as shown in FIGs. 6 and 7, the front end face of the back adaptor is shaped so as to make contact with the opposite end face of the cutting tool at a relatively flat portion, and not the sharp edge portion, so that a sufficiently rigid axial support is provided by the portional contact.

[38] The cutting tool is preferably provided with at least one coolant channel 150 for guiding a coolant flow from an opening 151,153 on a cutting head 110 to the opposite opening 152 on the other cutting head 120 such that each opening is disposed substantially at the same position relative to the cutting edge at each cutting head. For this positioning of the openings, the central straight part of the coolant channel is preferably machined within the cutting tool in a slanted orientation relative to the rotational axis S as shown in FIG. 8. In the embodiment of FIG. 8, the openings on both end faces of the cutting tool are blocked and other openings are bored in communication with the central straight part of the channel at the spots adjacent to the cutting edges for better cooling efficiency.

[39] As shown in FIG. 6, the limit screw 400 preferably has a central hole extending therethrough axially along the rotational axis, and the back adaptor 300 preferably has a central hollow extending axially along the rotational axis.

[40] The coolant flows from the rear side of the assembly, to the internally-threaded axial hole 240, through the central hole of the limit screw 400, through the central hollow of the back adaptor 300, and through the coolant channel of the cutting tool in order, and is then supplied onto the cutting edge.

[41] FIG. 9 illustrates another embodiment of the cutting tool assembly according to the present invention. In this embodiment, the tool holder housing 210 is provided with a slit 260 extending through the side wall of the housing at the radial position opposite to the internal ledge 230, and with side holes facing each other across the slit. The cutting tool is held in the tool holder by threading side tightening screws 510 down into the side holes of the tool holder housing. Mode for the Invention

[42] The disclosed cutting tool and the assembly comprising the same may have various modifications without departing from the basic concept of the present disclosure. Accordingly, all of the disclosed embodiments must be understood as being exemplary only and must not be construed to be the limit of the present disclosure. Accordingly, the range of protection for the present disclosure must be determined not by an embodiment described hereinabove, but by the attached claims. An alternative that is equivalent to the attached claims is included in the range of protection of the attached claims.

[43]

Claims

[1] A cutting tool 100 comprising two cutting heads 110, 120, each provided with a cutting edge 112, 122 or a cutting insert pocket 115,117, and a shank 130 extending between the two cutting heads; wherein the shank 130 is provided with a chip flute 140 formed on an outer peripheral surface 132 thereof so that the shank has a transversal cross section substantially that of a partial circle; and the chip flute 140 is formed by a pair of internal surfaces 141, 142 facing each other, and a cutting edge 112 or cutting insert pocket 115 is formed on the side of one internal surface 141 at one cutting head 110, while another cutting edge 122 or cutting insert pocket 117 is formed on the side of the other internal surface 142 at the other cutting head 120.

[2] The cutting tool of claim 1, wherein the pair of internal surfaces is two radial plane surfaces 141, 142 intersecting at the rotational axis S and facing each other at an angle.

[3] The cutting tool of claim 1, wherein the cutting tool is provided with a coolant channel 150 for guiding a coolant flow from an opening 151,153 on a cutting head 110 to the opposite opening 152 on the other cutting head 120 such that each opening is disposed substantially at the same position relative to the cutting edge or the cutting insert pocket at each cutting head with the central straight part of the coolant channel within the cutting tool machined in a slanted orientation relative to the rotational axis S.

[4] A cutting tool assembly 900 comprising a cutting tool 100 and a tool holder 200, wherein the cutting tool 100 comprises two cutting heads 110, 120 each provided with a cutting edge 112, 122 or a cutting insert pocket 115,117 and a shank 130 extending between the two cutting heads; the shank 130 is provided with a chip flute 140 formed on an outer peripheral surface 132 thereof so that the shank has a transversal cross section substantially that of a partial circle, wherein the chip flute 140 is formed by a pair of internal surfaces 141, 142 facing each other, and a cutting edge 112 or cutting insert pocket 115 is formed on the side of one internal surface 141 at one cutting head 110 while another cutting edge 122 or cutting insert pocket 117 is formed on the side of the other internal surface 142 at the other cutting head 120; the tool holder 200 comprises a housing 210 and a limit screw 400; the housing 210 is provided with a socket 220 extending axially inward from the front end surface 221 for receiving the cutting tool and provided with a in- ternally-threaded axial hole 240 extending axially inward from the rear end surface 241 and communicating with the socket 220, wherein the socket is provided with an internal ledge 230 extending axially on inner wall thereof such that the internal ledge is shaped so as to fit snugly into the chip flute 140 of the cutting tool; and the limit screw 400 is threaded into the internally-threaded axial hole 240.

[5] The cutting tool assembly of claim 4, wherein the tool holder housing 210 is further provided with one or more threaded radial through holes 250 extending through the side wall of the housing at the radial position opposite to the internal ledge 230 and communicating with the socket; and the tool holder 200 further comprises one or more side set screws 500 threaded into the threaded radial through hole 250.

[6] The cutting tool assembly of claim 4, wherein the cutting tool assembly 900 further comprises a back adaptor 300 having a transversal cross section substantially that of the partial circle, positioned between the cutting tool 100 and the limit screw 400, and axially extending over the region between the socket 220 and the internally-threaded axial hole 240 so that the back adaptor is received at least partially inside the socket 220.

[7] The cutting tool assembly of claim 6, wherein the maximum diameter of the socket 220 is smaller than the diameter of the internally-threaded axial hole 240.

[8] The cutting tool assembly of claim 4, wherein the tool holder housing 210 is further provided with a slit 260 extending through the side wall of the housing at the radial position opposite to the internal ledge 230, and has side holes facing each other across the slit, and the tool holder 200 further comprises at least one side tightening screw 510 seated into the side holes.

[9] The cutting tool assembly of claim 4, wherein the limit screw 400 has a central hole extending therethrough axially along the rotational axis.

[10] The cutting tool assembly of claim 6, wherein the back adaptor 300 has a central hollow extending axially along the rotational axis.