Cutter tool attachment for milling machines particularly useful to enable cutting sharp (or rounded) interior corners

Abstract

A cutter tool for a milling machine head, includes a conical cutter member defining a cone angle of substantially 70°. In one embodiment, the conical cutter member has a pointed apex, and in another embodiment, it has a rounded apex. Also described is an attachment for a milling machine head, wherein the conical cutter member is coupled at an angle of substantially 55° with respect to the axis of the milling machine head.

Description

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to cutter tool attachments for milling machines particularly useful to enable cutting sharp (or rounded) internal corners. The invention is therefore described below with respect to such an application, but it will be appreciated that various aspects of the invention could be used in other applications as well.

Milling machines, both the vertical type and horizontal type, are used for machining workpieces according to a large number of complex operations, such as slotting, planing, drilling, rebating, routing, etc. However, the conventional milling machine is not capable of making certain types of cuts, such as keyways and slots having sharp interior corners. Therefore when these types of cuts are required to be made, a conventional milling machine is generally used to cut the workpiece in an unfinished form, and then another working operation is performed on the workpiece, such as a laser machining or a chemical etching operation, in order to finish the workpiece with the desired sharp internal corners.

OBJECT AND BRIEF SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide a cutter tool for a milling machine head particularly useful for cutting sharp internal corners, but which may also be used for other cutting operations, such as for cutting rounded internal corners.

According to a broad aspect of the present invention, there is an attachment for a milling machine head comprising a conical cutter member defining a cone angle of substantially 70°.

In one described preferred embodiment, the conical cutter member has a pointed apex, and in a second described embodiment, it has a rounded apex.

The invention also provides such an attachment for a milling machine head wherein the attachment further comprises a shaft attachable to the milling machine head coaxial with the longitudinal axis of the milling machine head; and a coupling coupling the cutter tool to the shaft, with the rotary axis of the conical cutter member at a predetermined angle with respect to the longitudinal axis of the shaft. When the attachment is to be used for cutting interior corners, the predetermined angle is preferably substantially 55°.

As will be shown below, the cone angle of the conical cutter member mentioned above as being substantially 70°, is more precisely 70.52° (70° 31′ 12″); and the angle of the conical cutter member to the milling machine head longitudinal axis, mentioned above as being substantially 55°, is more precisely 54.74° (54° 44′ 24″).

Such an attachment may be constructed for attachment to a conventional milling machine in order to adapt it to perform various types of special cutting operations, such as cutting sharp internal corners, heretofore not possible or practicable by conventional milling machines.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a broken-away three-dimensional view illustrating one form of attachment for a milling machine head constructed in accordance with the present invention;

FIG. 2 a is an exploded view illustrating the attachment of FIG. 1;

FIG. 2 b is a sectional view illustrating the attachment of FIG. 1;

FIGS. 3 a, 3b and 3c are diagrams illustrating the external cutting surface of the conical cutter member of the attachment of FIG. 1; and, FIG. 3d illustrates the manner of computing the optimum angle of the conical cutter member rotary axis with respect to the longitudinal axis of the milling machine head;

FIG. 4 illustrates one manner of using the attachment of FIG. 1 for cutting a sharp interior corner in a workpiece;

FIG. 5 illustrates a modification in the attachment of FIG. 1, and the manner of using such an attachment for cutting sharp internal corners in a workpiece;

FIG. 6 illustrates the workpiece produced by using the attachment of FIG. 5 in the manner described;

FIG. 7 illustrates another use of the attachment of FIG. 5 for cutting various types of slots in the inner surface of a cylindrical workpiece;

FIG. 8 more particularly illustrates the conical cutter member of the cutter tool with a pointed apex; and

FIG. 9 more particularly illustrates the conical cutter member of the cutter tool with a rounded apex.

DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is described below with respect to a number of attachments constructed in accordance with the invention for attachment to a conventional milling machine head having a longitudinal axis about which a cutter tool is normally rotated when working a workpiece, in which the cutting operations are controlled by either moving the cutter tool with respect to the workpiece, or the workpiece with respect to the cutter tool. It will be appreciated that the constructions described below merely represent several preferred embodiments of the invention, and that the features of the invention, as defined in the appended claims, may be implemented in many other attachment constructions.

FIGS. 1, 2 a and 2b illustrate the basic components of one form of attachment constructed in accordance with the present invention for attachment to a milling machine head, schematically indicated at MMH, having a longitudinal axis LA about which a cutter tool is normally rotated when working a workpiece WP. As indicated above, the cutting operations may be controlled by either moving the cutter tool secured to the milling machine head MMH with respect to the workpiece WP, or vice versa.

The illustrated attachment includes a rotary shaft 2 couplable to the rotary drive of the milling machine head with the longitudinal axis of the shaft coaxial with the longitudinal axis LA of the milling machine head; and a conical cutter member 3 having an external cutting surface of a conical configuration. Conical cutter member 3 is coupled to rotary shaft 2 so as to be rotated thereby about a cutter member rotary axis RA (FIG. 2b) at a predetermined angle with respect to the longitudinal axis LA of the shaft. For this purpose, the illustrated attachment includes a coupling sleeve 4 attachable to shaft 2 with the longitudinal axis of the sleeve coaxial with the longitudinal axis LA of shaft 2, as well as of the milling machine head MMH. Coupling sleeve 4 thus couples the rotary cutter member 3 to rotate about the rotary axis RA (FIG. 2b). As will be described more particularly below, coupling sleeve 4 also permits angular adjustment of the rotary axis RA of the rotary cutter member 3 around the longitudinal axis LA of the shaft 2 and of the coupling sleeve 4. Coupling sleeve 4 is formed with an opening 5 with which cutter member 3 is aligned.

Coupling sleeve 4 is preferably of a hexahedral configuration. It is constructed of six walls 4a-4f perpendicular to each other, with opening 5 aligned with conical cutter member 3 being at the intersection of three of such perpendicular walls, two side walls 4a, 4b, and bottom wall 4f. A further embodiment however, is described below (FIG. 14) wherein the coupling sleeve may be of a cylindrical configuration.

Where the attachment is to be used for cutting sharp internal corners, the cone angle defining the external cutting surface of the conical cutter member is substantially 70°, more precisely 70.52° (70° 31′ 12′), and the rotary axis RA of the conical cutter member is substantially 55°, more precisely 54.74° (54° 44′ 24″). The latter is illustrated in FIG. 8 and by the diagrams of FIGS. 3a-3d.

FIG. 3 a is a three-dimensional diagram illustrating at 3a the external cutting surface of the conical cutter member 3; FIG. 3b is a side view illustrating at 3b the most-preferred cone angle of the conical cutter member; FIG. 3c is a plan view illustrating at 3c the large-diameter end of the conical cutter member 3; and, FIG. 3d illustrates the manner of computing the optimum angle of the conical cutter member rotary axis with respect to the longitudinal axis of the shaft.

As seen particularly in FIGS. 3a and 3b, when the conical cutter member 3 is formed with a pointed apex 3d, and its cone angle is precisely 70.52° (70° 31′ 12″), the conical cutter member 3 can cut sharp interior corners at the intersection lines of the three planar surfaces A, B, C. As seen in FIG. 3d, when the cone angle (α) of the conical cutter member is 70.52°, its rotary axis defines an angle (β), with the line normal to the longitudinal axis LA of shaft 2, of substantially 35.26° (35° 15′ 36″), whereby the angle (γ) defined by the rotary axis RA of the conical cutter member (being complementary to β) is 54.74° (54° 44′ 24″).

FIGS. 2 a and 2b more particularly illustrate the construction of the attachment of FIG. 1. In addition to the rotary cutter member 3 carried by coupling sleeve 4 with respect to shaft 2, the attachment includes: a clamping sleeve 10 clamping the rotary shaft 2 of the attachment to the rotary drive of the milling machine head MMH to rotate shaft 2 about its longitudinal axis; a bevel gear 11 at one end of rotary shaft 2: and a bevel gear 12 meshing with bevel gear 11 and coupled to the conical cutter member 3 to rotate it about its rotary axis RA, which at a predetermined angle with respect to the longitudinal axis LA of shaft 2. The illustrated attachment further includes a pair of bearings 13a, 13b for rotatably mounting shaft 2 with respect to sleeve 10; and further bearings 14 and 15 for rotatably mounting bevel gear 12 and cutter member 3 with respect to coupling sleeve 4. Bevel gear 12 is coupled to conical cutter member 3 by a chuck 16 receiving shank 17 of the conical cutter member 3.

As indicated earlier particularly with respect to the diagram of FIG. 3a, cutter member 3 is formed with a sharply-pointed apex (3d) aligned with opening 5 in coupling sleeve 4 and flush with the outer surface of the coupling sleeve in order to permit the cutter member to cut sharp interior corners in the workpiece. An attachment constructed in accordance with the present invention, however, may be used in other applications as will be described more particularly below, e.g., wherein the conical cutter member 3 need not have a sharply-pointed apex (e.g., see FIG. 9), and/or need not be flush with the outer surface of the coupling sleeve. For this purpose, FIG. 2a illustrates the chuck 16 of the attachment as including a threaded pin 18 which permits the conical cutter member 3 to be axially adjusted with respect to opening 5 in coupling sleeve 4. Threaded pin also permits a conical cutter member having a sharply-pointed apex, as shown at 3 in FIG. 8, to be replaced by a cutter member having another apex, e.g., a rounded apex (as shown at 3′ in FIG. 9), or a relatively flat apex.

As indicated earlier, coupling sleeve 4 is preferably of a hexahedral configuration, including four sides walls 4a-4d, a top wall 4c, and a bottom wall 4f, all perpendicular to each other. Opening 5 for the conical cutter member 3 is formed in the intersection of two side walls 4a, 4b, and bottom wall 4f; the top wall 4c is formed with an opening for receiving the rotary shaft 2 to be coupled to the rotary drive of the milling machine head.

FIG. 4 more particularly illustrates how the attachment of FIGS. 1, 2a, 2b may be used for cutting sharp interior corners in a workpiece WP formed with a wall 20. Thus, as shown in FIG. 4, by locating coupling sleeve 4 of the attachment within a slot 21 in the workpiece wall 20, the rotary cutter member 3 will cut sharp interior corners between surfaces 20a, 20b, 20f, engageable by surfaces 4a, 4b, 4f, respectively, of the attachment coupling sleeve 4.

FIGS. 5 and 6 illustrate one manner in which the above-described attachment may also be used for cutting, in a wall of workpiece 20, an internal slot 22 having sharp interior corners. For this purpose a guiding element, in the form of a spline 30 (FIG. 5), may be fixed to the outer surface of coupling sleeve 4 to extend parallel to its longitudinal axis and that of its rotary shaft 2. Spline 30 may be provided with an external configuration corresponding exactly to that of the finished slot 22 to be formed in workpiece 20. Thus, such a slot may be initially produced by any conventional attachment such that it would not have sharp internal corners. When the slot is to be finished with sharp internal corners, the attachment of FIG. 6 would be applied to the workpiece with spline 30 received within the unfinished slot 22. Since the outer surface of spline 30 exactly conforms to the inner surface of the slot 22 to be formed, it will be seen that the spline includes two sharp outer corners exactly conforming to the two sharp interior corners to be formed in the slot.

When using the attachment in the manner described with respect to FIG. 5, the apex of the conical cutter member 3 would be projected outwardly of opening 5 in coupling sleeve 4 to be flush with the outer surface of one corner of spline 30, and thereby to cut one sharp interior corner in slot 22. Spline 30, when so used, not only guides the movement of the conical cutter member parallel to the rotary axis of shaft 2, but also prevents rotation of the coupling sleeve 4 by the rotating conical cutter when the conical cutter member is moved out of contact with the workpiece.

After one sharp interior corner of slot 22 has thus been cut, the attachment is removed from the workpiece, and sleeve 40 is rotated slightly to align the apex of the conical cutter member 3 with the other external corner of spline 30. The attachment is then reintroduced into the slot whereupon the spline guides the movement of the conical cutter member 3 to cut the other sharp interior of the slot. During the latter movement, spline 30 also guides the movement of the conical cutter member parallel to the rotary axis of shaft 2 to cut the respective interior corner, and also prevents rotation of the coupling sleeve 4 when the conical cutter member is moved out of contact with the workpiece.

It will be appreciated that the illustrated attachment could be used without spline 30, but with other guiding and/or rotational-blocking arrangements, such as may be provided in CNC milling machines, for guiding the movement of the attachment with respect to the workpiece and for blocking the rotation of the coupling sleeve when the cutter member is cutting the respective interior corner in the workpiece.

FIG. 7 more particularly illustrates the manner of using the above-described attachment, including the spline 30, for cutting sharp internal corners in a rectangular slot 23 in the inner surface of a hollow shaft. Thus, as described above, when so using the attachment, its conical cutter member 3 would be properly located with its apex in axial alignment with one corner of spline 30, and then in alignment with the other corner of the spline.

FIG. 7 also illustrates how the attachment may also be used to cut V-slots 24 and rounded slots 25 in the inner face of the hollow shaft. When a rounded slot 25 is to be cut, this may be conveniently done by replacing the conical cutter member 3 with one having a rounded apex as shown at 3′ in FIG. 9.

While the invention has been described with respect to several preferred embodiments, it will be appreciated that many other variations and modifications may be made.

Many other variations, modifications and applications of the invention will be apparent.

Claims

1. An attachment for a milling machine head, comprising a cutter tool having a conical cutter member defining a cone angle of substantially 70°.

2. The attachment according to claim 1, wherein said conical cutter member has a pointed apex.

3. The attachment according to claim 1, wherein said conical cutter member has a rounded apex.

4. The attachment according to claim 1, wherein said attachment further comprises: a shaft attachable to the milling machine head coaxial with the longitudinal axis of the milling machine head; and a coupling the cutter tool to said shaft with the rotary axis in the conical cutter member at a predetermined angle with respect to the longitudinal axis of the shaft.

5. The combination according to claim 4, wherein said predetermined angle is substantially 55°.

6. The combination according to claim 4, wherein said coupling includes meshing bevel gears.