Mounting device for cutting tools

Abstract: The invention provides a simplified mounting device for the connection of a cutting tool to a machine spindle. The mounting device is of two-piece structure, one piece consti­ tuting an arbor (10) connectable to the spindle, the other constituting a tool holding adapter (11). The adapter (11) is connected to the arbor (10) by means of a clamping bolt (13). An accurate centering and rigidity is attainable at the mounting of the tool due to the provision of a cylindrical extension (16) on said adapter, which comprises two cylin­ drical portions having slightly different diameters and being adapted to engage corresponding surfaces in a bore (12) in the arbor (10).

Description: The present invention relates to a mounting device for the connection of a rotary cutting tool to a machine spindle comprising a conical arbor for connection to the spindle, an adapter for connecting the cutting tool to the arbor and having a cylindrical extension extending from its main portion, the adapter being directly clampable in use to the arbor by means of a clamping bolt such that a radial flange at the junction between main portion and cylindrical extension is clamped in axial abutment to a front face of the arbor, thus constituting an assembly attachable in operation as a single unit to a machine spindle, the adapter having an internal thread portion located within said cylindrical extension for engagement in use with an exterior threaded portion of the bolt at its tool-oriented end portion. The invention also relates to an adapter designed to be used in the mounting device. A mounting device of the above type is previously known from DE-A 25 41 123. Said device offers extensive interchangeability of cutting tools between machining centers regardless of spindle specifications. By matching the arbor to the individual machine spindle, any adapter for a specific operation can be used in any machine, thereby effectively reducing or eliminating the need to purchase and stock duplicate tools for each machine. DE-U-78 27 203, whilst describing a cylindrical extension having two surface portions of slightly different diameter, carries an external thread for direct engagement with a corresponding thread on the arbor. The object of the invention is to provide a connection between the arbor and the adapter which is as strong as possible. Another object of the invention is to ensure positive drive of the adapter as well as correct orientation of the cutting edge. These and other objects of the invention are attained by giving the invention the characterizing features stated in the appending claims 1 and 3 respectively. The invention is described in detail in the following with reference to the accompanying drawings in which one embodiment is shown by way of example. It is to be understood that this embodiment is only illustrative of the invention and that various modifications thereof may be made within the scope of the claims. In the drawings, Fig. 1 is an axial sectional view of the arbor member of the mounting device, and Fig. 2 is an axial section view of the adapter showing also a rotary cutting tool entered thereinto. Referring now to Figs. 1-2 of the drawing, there is shown an arbor 10 and a tool adapter 11 as described in our parent patent EP-B-015 248. The arbor 10 has a bore 12 extending centrally therethrough, the upper portion of which is connectable with the machine spindle by means of a threaded bolt (not shown). The lower portion of the bore 12 is enlarged and receives a clamping bolt 13 which at its lower end portion has an external thread 14 adapted to engage a corresponding internal thread 15 of an axially extending cylindrical centering portion 16 of the adapter 11, which is to be received in a corresponding portion of the bore 12 upon clamping. The internally threaded portion 15 of the adapter 11 provides the upper portion of a central bore extending through the adapter, the lower portion 17 of said bore being adapted to receive a rotary cutting tool 18 which is a drill. The clamping bolt 13 is axially fixed in the bore 12 by the provision of an annular abutment surface 20 on the underneath side of the head 19 of the bolt oriented perpendicular to the axis of said bolt and intended for abutment against the upper end surface 21 of a sleeve member 23, that is threadably engaged at 22 into the above related enlarged portion of the bore 12. The lower end portion of said sleeve member 23 is a flange portion 24 adapted to engage with a correspondingly shaped shoulder abutment 25. The axially extending centering portion 16 of the adapter 11 is provided with two cylindrical portions 27 and 28 of differing diameters intended to be used as peripheral guiding surfaces. The upper surface 27 in Fig. 2 has a slightly less diameter than the axially rear surface 28, both said surfaces being intended upon mounting to slide with a close interfit against corresponding guide surfaces 29 and 30 respectively provided at the lower portion of the bore 12. The upper or distal surface 27 serves as a guide for inserting the adapter 11 in the bore 12 in the arbor. The clamping bolt 13 serves to clamp the adapter 11 directly to the arbor 10 so as to form a unit separable from the spindle. The end surface 31 of the axial centering portion 16 is radially extending. The adapter 11 is furthermore provided with a radial flange 32 located behind said centering portion 16 which is adapted to abut against the lower end surface of the arbor 10 in order to reach an axially fixed position. The dimensioning and formation of the centering portion 16 is such that the internal threaded portion 15 thereof and correspondingly threaded portion 14 of the clamping bolt 13 extend in length substantially in excess of the total length of guiding surfaces 27, 28. This improves the moment stability when mouning the adapter 11 into the arbor 10, at the same time as the centrally located clamping bolt 13 gives a high claimping force in the mounting which stabilizes the conditions. The function of the centering portion 16 is to achieve a tool mounting without play caused by clearances, minimize radial off-setting of the cutting tool, and to provide a strong connection between the arbor and the adapter. The maintenance of these conditions requires that the resulting interfit is made rather accurate which hitherto has caused jamming conditions for the cutting tools upon the mounting thereof. Due to the provision of a centering portion composed of sections of slightly various diameters it has been found that any jamming can be almost entirely avoided. According to the invention the adapter 11 may be secured against rotation relative to the arbor by means of a wedge 34 receivable in the radial flange portion 32, said wedge being connected to the adapter by means of a radial bolt 35 and adapted to be received in a complementary wedging slot 36 within the arbor 10. The wedge 34 may be arranged radially outwardly of the rear surface portion 28 on only one side of the adapter and extends toward the arbor from a surface abutting a surface on the arbor. The advantage of providing a wedge 34 that is mounted on the tool that is being rotated i.e. the adapter 11, instead of mounted on the member that causes rotation, i.e. the arbor, is the fact that the wedge supporting member is the member that can be easiest damaged if the tooling structure collapses. Usually the adapter is provided with wedge means also at its tool oriented end portion which also are susceptible to damages. If the wedge 34 is provided in the adapter 11 those members easiest susceptible to damages will be located on the same member. This substantially lessens the risk of tool failure and enables reduction of costs. The adapter 11 is furthermore provided with only one wedge 34 which enables mounting of the arbor to be effected in only one manner which is an advantage since working with single cutting tools in tooling centre is absolutely necessary for exact knowledge of the position of the cutting edge in relation to the keying members of the machine spindle.

Claims: A mounting device for the connection of a rotary cutting tool (18) to a machine spindle, comprising a conical arbor (10) for connection to the spindle, an adapter (11) for connecting the cutting tool (18) to the arbor (10) and having a cylindrical extension (16) extending from its main portion, the adapter (11) being directly clampable in use to the arbor (10) by means of a clamping bolt (13) such that a radial flange at the junction between main portion and cylindrical extension (16) is clamped in axial abutment to a front face of the arbor, thus constituting an assembly attachable in operation as a single unit to a machine spindle, the adapter (11) having an internal thread portion (15) located within said cylindrical extension (16) for engagement in use with an exterior threaded portion (14) of the bolt (13) at its tool-oriented end portion, characterized in that the cylindrical extension (16) has two cylindrical surface portions (27,28) of slightly different diameters, the distal surface portion (27) having a slightly smaller diameter than the other surface portion (28), the bore (12) of the arbor (10) having two guide surfaces (29,30) which upon mounting slide with close interfit against the two cylindrical surface portions (27,28), said distal surface portion serving as a guide for detachably inserting the adapter in the bore (12) in the arbor, and that the internal thread portion (15) in the cylindrical extension of the adapter extends through both cylindrical surface portions (27,28). Mounting device according to claim 1, comprising a wedge (34) on the adapter (11) for preventing relative rotation between the arbor (10) and said adapter, said wedge being arranged radially outwardly of said other surface portion (28) on only one side of said adapter and extending toward said arbor from a surface abutting a surface on said arbor, whereby the wedge is positively receivable in a corresponding recess (36) in the front face of the arbor (10). Adapter for use in a mounting device according to claims 1 and 2 in connecting a cutting tool (18) to an arbor (10) receivable in a machine spindle, the adapter (11) being connectable to the cutting tool (18) and having a cylindrical extension (16) extending from its main portion in a direction opposed to the cutting tool, an internal thread portion (15) being located within said cylindrical extension (16), characterized in that the cylindrical extension (16) has two cylindrical surface portions (27,28) of slightly different diameters, the distal surface portion (27) having a slightly smaller diameter than the other surface portion (28), the bore (12) of the arbor (10) having two guide surfaces (29,30) which upon mounting slide with close interfit against the two cylindrical surface portions (27,28), said distal surface portion serving as a guide for detachably inserting the adapter in the bore (12) in the arbor, the internal thread portion (15) in the cylindrical extension of the adapter extends through both cylindrical surface portions (27,28) and the adapter is further provided with a wedge (34) for preventing relative rotation between an arbor and the adapter, said wedge being arranged radially outwardly of said other surface portion (28) on only one side of the adapter and extending away from a surface of the adapter abutting in use a surface on the arbor. Adapter according to claim 3, wherein the internal thread portion (15) of the adapter has an axial length in excess of the total length of the cylindrical extension of the adapter.

Inventors: ANDERSON KEN GOETE ESKIL, ANDERSON, KEN GOETE ESKIL, Anderson, Ken Göte Eskil
Applicants: SANDVIK AB, SANDVIK AKTIEBOLAG
Application year: 1980
Main classification: B23B31
IPC codes: B23B51, B23C5, B23B31, B23Q3