HK1142030A

HK1142030A - Multi-piece tool assembly and cutting tool

Info

Publication number: HK1142030A
Application number: HK10108612.9A
Authority: HK
Inventors: Karl-Erik Bergloew; Christer Joensson
Original assignee: 山高刀具公司
Priority date: 2007-07-03
Filing date: 2008-06-10
Publication date: 2010-11-26

Description

Multi-piece tool assembly and cutting tool

Technical Field

The present invention relates generally to multi-piece tools, and more particularly to tools having an arrangement for distributing the fastening force between tool components.

Background

Many modern cutting tools use replaceable cutting inserts that are made of extremely hard materials, such as cemented carbide. The insert may be mounted on a toolholder or shank made of a more common and easier to machine material that is generally less rigid than the insert and less brittle than the insert. In the sense used herein, "brittle" means that the blade may have a young's modulus about six times higher than that of ordinary steel. Care must be taken in using such blades to avoid breakage.

Disclosure of Invention

It is desirable to provide a multi-piece tool assembly, particularly a cutting tool assembly, having a box member and a pin member, wherein the risk of damaging the box member during tightening can be reduced.

According to one aspect of the invention, a multi-piece tool assembly comprises: a pin member having an external thread; and a box member having an opening adapted to receive at least a portion of the pin member to a predetermined depth and an internal thread adapted to mate with the external thread of the pin member. When the pin member is received within the opening to a predetermined depth, substantially all of the force between the external and internal threads is directed along the axis of the box member, and the working portion of the tool assembly is disposed on one of the pin member and the box member.

According to another aspect of the invention, a cutting tool comprises: a box member having an opening adapted to receive at least a portion of a pin member to a predetermined depth and an internal thread adapted to mate with the external thread of the pin member, a force-bearing flank of the internal thread extending substantially perpendicular to an axis of the box member; and a working portion of a tool provided on the female threaded member.

According to another aspect of the invention, a cutting tool comprises: a pin member having an external thread, the pin member adapted to be at least partially received within the opening of the box member to a predetermined depth, the external thread adapted to mate with the internal thread of the box member, the force-bearing flank of the external thread extending substantially perpendicular to the axis of the pin member and the box member; and a working portion of a tool assembly disposed on the male threaded member.

Drawings

The features and advantages of the present invention will be best understood by reading the following detailed description in conjunction with the accompanying drawings, in which like reference characters designate like elements, and in which:

FIG. 1 is a cross-sectional view of a multi-piece tool assembly according to one aspect of the present invention;

FIGS. 2A-2B are top and bottom perspective views of a multi-piece tool assembly according to aspects of the present invention;

FIGS. 3A-3B are side views of a multi-piece tool assembly according to aspects of the present invention; and

FIG. 4 is a cross-sectional view of a multi-piece tool assembly according to another aspect of the invention.

Detailed Description

A multi-piece tool assembly 21 according to one aspect of the present invention is shown in cross-section in fig. 1. The assembly 21 comprises: a male threaded member 23, the male threaded member 23 having an external thread 25; and a box member 27, the box member 27 having an opening 29 adapted to receive at least a portion of the pin member to a predetermined depth and an internal thread 31 adapted to mate with the external thread of the pin member.

One type of cutting tool that is an aspect of the present invention is applied for U.S. patent application publication 2006/0062642, which is incorporated by reference. U.S. patent application publication 2006/0062642 discloses a cutting tool having a replaceable cutting insert or head, wherein the head is provided with internal threads that mate with external threads on the shank to secure the head to the shank. The applicant has noted the risk in such multi-piece tools that use basic thread profiles. With such a thread profile, forces are transmitted between the adjoining flanks of the thread when the tool bit is fastened to the tool shank. The force component of the force is directed radially outward from the axis of the tool due to the angle of the adjoining flanks. This radially outward force component can damage the female component, particularly components such as cemented carbide components that may break when subjected to the force.

When the pin member 23 is received within the opening 29 to a predetermined depth, substantially all of the force between the external thread 25 and the internal thread 31 is directed along the axis AF of the box member. The working portion 33 of the tool assembly 21 is disposed on one of the pin member 23 and the box member 27. In the embodiment shown in fig. 1, the working portion 33 is integrally formed with the box member 27, as also shown in fig. 2A-2B. The male threaded member 23 can form a portion of the shank 35 of the tool assembly 21 or other components of the tool assembly 21.

Substantially all of the force between the external and internal threads 25, 31 is transferred between the flanks 37, 39 of the external and internal threads, respectively, which flanks 37, 39 extend substantially perpendicular to the axes AM and AF of the pin member 23 and the box member 27, respectively. The back or flanks 41, 43 on the opposite side of the pin 25 and box 31 from the substantially perpendicular flanks 37 and 39, respectively, can form a non-zero angle with the substantially perpendicular flanks and the axes AM and AF of the pin member and the box member, and generally do not substantially transmit forces therebetween.

A thread according to one aspect of the invention is in the form of a non-sealing thread having a front face substantially perpendicular to the axis of the thread and a back face at an angle to the axis, so that the thread is more efficient in transferring power and is also stronger.

An abutment surface 45 may be provided on the male threaded member 23 and an abutment surface 47 may be provided on the female threaded member 27. The abutment surfaces 45 and 47 may be arranged to limit the extent to which the male threaded member 23 is adapted to be received within the opening 29 to a predetermined depth. In FIG. 1, the abutment surface 45 on the male threaded member 23 is shown as extending radially outside the outer diameter of the external thread 25. The abutment surface 45 on the male threaded member 23 includes a portion 49 that is substantially perpendicular to the axis AM of the male threaded member, and a portion 51 that is non-perpendicular to the axis of the male threaded member and is generally frustoconical.

The abutment surface 47 on the female threaded member 27 may include a portion 53 that is substantially perpendicular to the axis AF of the female threaded member, and a portion 55 that is not perpendicular to the axis of the female threaded member and is generally frustoconical. When the pin member 23 is received in the opening 29 of the box member 27 to a predetermined depth, the portions 53 and 55 can abut the portions 49 and 51, thereby limiting the extent to which the pin member can be received in the opening. In addition, the provision of the non-perpendicular components 51 and 55 can facilitate proper alignment of the axes AM and AF of the pin member 23 and the box member 27.

The perpendicular portions 49 and 53 and the non-perpendicular portions 51 and 55 can help prevent over tightening of the pin member 23 and the box member 27. The external and internal threads 25, 31 may be disposed relative to the abutment surfaces 45, 47 on the pin member 23 and the box member 27, respectively, such that a predetermined securing force is transmitted between the external and internal threads when the pin and box members are disposed in a predetermined relative axial rotational position. Since the pin member 23 and the box member 27 are tightened with respect to each other, the non-perpendicular portions 51 and 55 can contact each other before the pin member is located in the opening 29 of the box member to a predetermined depth. At this time, the resistance to rotation of the pin member 23 relative to the box member 27 will increase as the pin member extends into the opening closer to the predetermined depth and the axes AM and AF of the pin and box members are properly aligned. By properly forming the external thread 25 and the internal thread 31 relative to the perpendicular components 49 and 53 and the non-perpendicular components 51 and 55, the resistance to rotation of the pin member 23 relative to the box member 27 can be increased by a combination of contact between the non-perpendicular components 51 and 55 and contact between the perpendicular flanks 37 and 39 of the external and internal threads such that the force applied between the perpendicular flanks provides the desired securing force at or near the point where the perpendicular components 49 and 53 abut and prevent further relative axial movement of the pin member 23 relative to the box member 27.

While the abutment of the perpendicular portions 49 and 53 prevents further relative axial movement of the pin member 23 with respect to the box member 27, and the resistance to further tightening rotation of the pin member with respect to the box member is now substantially increased, the abutment need not prevent further rotation of the pin member with respect to the box member. Accordingly, markings may be provided on the pin member 23 and the box member 27 to indicate approximate relative rotational positions of the pin member and the box member when a predetermined securing force between the external thread 25 and the internal thread 31 has been reached. The indicia may be in any suitable form, such as markings 57 and 59 on the sides of the pin member 23 and the box member 27 seen in FIG. 3A, or such as ridges 61 and 63 on the vertical portions 49 and 53 of the abutment surfaces 45 and 47 seen in FIG. 3B, the ridges 61 and 63 being sufficiently sized to effectively prevent further relative rotation of the pin member with respect to the box member.

As can be seen in FIG. 1, the abutment surface 47 on the female threaded member 27 forms a male member, while the abutment surface 45 on the male threaded member 23 forms a female member adapted to receive the male member. Thus, during tightening of the male threaded member 23 relative to the female threaded member 27, as the male abutment surface 47 enters the female abutment surface 45, a radially outwardly directed force component is applied to the female abutment surface 45. Thus, the female abutment surface 45 is typically sized sufficiently to avoid damage during tightening. In the embodiment shown in FIG. 1, the female abutment surface 45 is the portion of the tool assembly 21 not having the working portion 33 and may be, for example, a shank 35. Especially when the portion of the tool assembly 21 having the working portion 33 is made of a brittle material, it is desirable that the female abutment surface 47 be the portion of the tool assembly not having the working portion 33 such that radially directed forces on the working portion are directed radially inward rather than radially outward, which may increase the likelihood of the portion breaking away from the working portion.

FIG. 4 shows an embodiment of the multi-piece tool assembly 121 in which the abutment surface 147 on the male threaded member 123 extends radially inward of the outer diameter of the external thread 125. Likewise, an abutment surface 145 on the female threaded member 127 extends radially inward of the inner diameter of the internal thread 131. As shown in phantom, the abutment surfaces 145 and 147 can have components that are perpendicular and non-perpendicular to the axis of the pin member and the box member and function in a manner similar to the perpendicular and non-perpendicular components described in connection with FIG. 1. Further, the working portion may be provided on the pin member or the box member.

The external thread 25, 125 and the internal thread 31, 131 preferably each comprise only 1 to 3 thread turns in order to have a short tool length. It has also been found to be advantageous to form the external and internal threads slightly conical in fig. 1 with the cone apex pointing downwards. Each cone may have a cone angle of about 2 °. The tool may have one or more flushing channels.

While the invention has been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.

The disclosure of swedish patent application No.0701623-1, from which this application claims priority, is hereby incorporated by reference.

Claims

1. A multi-piece tool assembly (21, 121), comprising:

a pin member (23, 123), the pin member (23, 123) having an external thread (25, 125); and

a box member (27, 127), the box member (27, 127) having an opening (29) adapted to receive at least a portion of the pin member (23, 123) to a predetermined depth and an internal thread (31, 131) adapted to mate with the external thread (25, 125) of the pin member (23, 123),

characterized in that, when the male threaded member (23, 123) is received within the opening (29) to the predetermined depth, substantially all of the force between the external thread (25, 125) and the internal thread (31, 131) is directed along the axis of the female threaded member (27, 127), and a working portion (33) of the tool assembly is disposed on one of the male threaded member (23, 123) and the female threaded member (27, 127).

2. The multi-piece tool assembly (21, 121) as set forth in claim 1, characterized in that, when the pin member (23, 123) is received within the opening (29) to the predetermined depth, substantially all of the force between the external thread (25, 125) and the internal thread (31, 131) is transferred between the external thread (25, 125) and a flank (37, 39) of the internal thread (31, 131), the flank (37, 39) extending substantially perpendicular to the axis of the pin member (23, 123) and the box member (27, 127).

3. The multi-piece tool assembly (21, 121) as set forth in claim 2, characterized in that flanks (41, 43) on opposite sides of the external (25, 125) and internal (31, 131) threads from the substantially perpendicular flanks (37, 39) form a non-zero angle with the substantially perpendicular flanks and with the axis of the pin (23, 123) and box (27, 127) threads when the pin (23, 123) is received in the opening (29) to the predetermined depth.

4. The multi-piece tool assembly (21, 121) as set forth in claim 3, characterized in that the opposing flanks (41, 43) substantially do not transmit forces between the external threads (25, 125) and the internal threads (31, 131) when the male threaded member (23, 123) is received within the opening (29) to the predetermined depth.

5. The multi-piece tool assembly (21, 121) as set forth in claim 2, characterized in that the opposing flanks (41, 43) substantially do not transmit forces between the external threads (25, 125) and the internal threads (31, 131) when the male threaded member (23, 123) is received within the opening (29) to the predetermined depth.

6. The multi-piece tool assembly (21, 121) as set forth in claim 1, characterized in that the tool assembly includes an abutment surface (45, 145) on the male threaded member (23, 123) and an abutment surface (47, 147) on the female threaded member (27, 127), the abutment surfaces being arranged to limit the extent to which the male threaded member (23, 123) is adapted to be received within the opening (29) to the predetermined depth.

7. The multi-piece tool assembly (21, 121) as set forth in claim 6, characterized in that the abutment surface (45) on the male threaded member (23, 123) extends radially outside an outer diameter of the external thread (25, 125).

8. The multi-piece tool assembly (21, 121) as set forth in claim 7, characterized in that the abutment surface (45) on the male threaded member (23, 123) includes a portion (49) that is substantially perpendicular to an axis of the male threaded member (23, 123).

9. The multi-piece tool assembly (21, 121) as set forth in claim 8, characterized in that the abutment surface (45) on the male threaded member (23, 123) includes a portion (53) that is non-perpendicular to the axis of the male threaded member (23, 123).

10. The multi-piece tool assembly (21, 121) as set forth in claim 8, characterized in that the non-perpendicular component (53) is frustoconical.

11. The multi-piece tool assembly (21, 121) as set forth in claim 7, characterized in that the abutment surface (45) on the male threaded member (23, 123) includes a portion (53) that is non-perpendicular to an axis of the male threaded member (23, 123).

12. The multi-piece tool assembly (21, 121) as set forth in claim 11, characterized in that the non-perpendicular component (53) is frustoconical.

13. The multi-piece tool assembly (21, 121) as set forth in claim 11, characterized in that the abutment surface (47) on the female threaded member (27, 127) includes a portion (55) that is non-perpendicular to an axis of the female threaded member (27, 127).

14. The multi-piece tool assembly (21, 121) as set forth in claim 13, characterized in that the abutment surface (47) on the female threaded member (27, 127) defines a male member and the abutment surface (45) on the male threaded member (23, 123) defines a female member adapted to receive the male member.

15. The multi-piece tool assembly (21, 121) as set forth in claim 6, characterized in that the abutment surface (145) on the male threaded member (23, 123) extends radially inward of an outer diameter of the external thread (25, 125).

16. The multi-piece tool assembly (21, 121) as set forth in any of the preceding claims, characterized in that the external thread (25, 125) and the internal thread (31, 131) each comprise only 1 to 3 thread turns.

17. The multi-piece tool assembly (21, 21) as set forth in claim 1, characterized in that one of said pin member (23, 123) and said box member (27, 127) is made of cemented carbide on which said working portion (33) of the tool is disposed.

18. A cutting tool, comprising: a box member (27, 127), the box member (27, 127) having an opening (29) adapted to receive at least a portion of a pin member (23, 123) to a predetermined depth and an internal thread (31, 131) adapted to mate with an external thread (25, 125) of the pin member (23, 123); and a working portion (33) of the tool, the working portion (33) being provided on the box member (27, 127), characterized in that a force-bearing flank (39) of the internal thread (31, 131) extends substantially perpendicular to the axis of the box member (27, 127).

19. A cutting tool, comprising: a male threaded member (23, 123) having an external thread (25, 125), the male threaded member (23, 123) being adapted to be at least partially received within the opening (29) of the female threaded member (27, 127) to a predetermined depth, the external thread (25, 125) being adapted to mate with the internal thread (31, 131) of the female threaded member (27, 127); and a working portion (33) of the tool assembly, the working portion (33) being disposed on the pin member (23, 123), characterized in that the force-bearing flank (37) of the external thread (25, 125) extends substantially perpendicular to the axis of the pin member (23, 123) and the box member (27, 127).