WO1995035179A1

WO1995035179A1 - Boring bar and holder

Info

Publication number: WO1995035179A1
Application number: PCT/US1995/006828
Authority: WO
Inventors: Gregory S. Antoun
Original assignee: Antoun Gregory S
Priority date: 1994-06-22
Filing date: 1995-05-23
Publication date: 1995-12-28
Also published as: AU2657295A

Abstract

A boring bar (12) and a boring bar holder (14). The boring bar (12) has a cylindrical body (16) having a tool end (20) with two flat surfaces (24, 26) adjacent the tool end (20) and disposed at ninety degrees to each other and at forty-five degrees to a center line of the cylindrical body (16). A journal member (28) makes line contact with the cylindrical body (16) along a line passing through the center line of the cylindrical body (16).

Description

BORING BAR AND HOLDER

BACKGROUND OF THE INVENTION This invention relates to boring bars, threading bars, grooving bars, holders for boring bars and the like, referred to herein as "boring bars", boring bar holders and more particularly, to a tool and holder that greatly increases rigidity due to its design. The tool always locates the cutting edge on the center of the applied forces. Three force vectors: vertical, horizontal and lateral, affect a tool in boring. The current practice is to use a round boring bar holder that holds the boring bar in place with set screws. The problem is that the round bar is forced to one side of the boring bar holder and because the bar is round and the holder is round, there is contact only along a line. In some cases, a flat surface is formed on the bar that causes two lines of contact. The use of set screws to hold the bar from turning in the holder also limits the torque that can be applied to the tool. When a tool, smaller than the receiving opening in the holder is used, a precision bushing is required to maintain alignment. The manufacturer generally supplies a precision bushing with a round boring bar. The outside diameter of each bushing must be slightly smaller than the outside diameter of the holder and slightly larger than the inside diameter of the bar. The major disadvantages of the current practice in conventional tool holders are: 1. There is a very small area of contact between the bar and the holder. 2. There is no positive stop for length. The tool must be set to its appropriate position and, a scale used to set the tool. The cutting edge is frequently misaligned. 3. The direction of pressure used to hold the tool in conventional tool holders are not correct. Set screws push the tool against the side of the holder at 90 degrees to the largest force vector. 4. The alignment of the tool is changed by differences in torque applied to the set screws. 5. The total amount of torque that can be applied to hold the tool in conventional tool holders is relatively small compared to the V-Bar structure of the present invention. In addition, the conventional tool holder exerts a force in the wrong direction. For example, with three 5/16" set screws torqued at 13.3 foot-pounds equals 39.9 foot-pounds. Six 3/8" socket head bolts torque at 48.3 foot¬ pounds at each end is equal to 289.8 foot-pounds. 6. The set screws of the conventional tool holder must be set in from the edge of the standard tool holder causing the actual unsupported length of the boring bar to be longer and therefore, inherently less rigid than in the present invention. 7. Conventional tool holders and boring bars are subject to major problems with harmonic vibration (chatter) due to a lack of rigidity. 8. Each size of boring bar requires an individual holder or bushing. Separate inventories must be maintained for all metric and inch sizes. With conventional tool holders, each time a tool size is changed, the tool holder must be replaced on the machine, thereby increasing set up time and increasing the potential for human error.

SUMMARY OF THE INVENTION The system described in this application greatly reduces the problems associated with the three axis of the forces on the tool and provides a positive location of the tool radially. The boring bar is located by flat surfaces on the bar at a ninety degree angle to each other and forty-five degrees from the boring bar's center line. Journals hold the bar in the V formed by the flat surfaces and larger bolts eliminate any movement of the boring bar. As a result, the tool is capable of greater extension and is less prone to harmonics, commonly called chatter than in conventional tools.

The major advantages of applicant's V-Bar system are: 1.

The V-Bar system aligns the boring bar and clamps on two flat surfaces giving it a large contact area. 2. Applicant's force of clamping is in the direction of the major detrimental force vector, greatly enhancing rigidity. 3. Applicant's system is self aligning with the center, but can easily and accurately be adjusted above or below center with the simple insertion of a standard shim under one of the flats. 4. Applicant's boring bar is supported and clamped to the face of the tool holder effectively minimizing overhang and effectively increasing the rigidity of the bar. 5. Applicant's holder is equipped with a stop system so that the bars can not be pushed out of its end position and all tooling can be quickly changed. 6. Because applicant's tool is self-aligning and is clamped against flat surfaces at ninety degrees to each other, one V- Bar holder can hold any size of boring bar without removal of the holder from the machine or the need for bushings.

Therefore set up time, and cost of tooling machines are reduced. 7. A thin sheet of elastomer can be clamped between applicant's V-Bar and tool holder to additionally damp vibration in the V-Bar system. This is possible in the V-Bar system because clamping pressure deforms the elastomer evenly maintaining the alignment of the centerline of the boring bar.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawing and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention. BRIEF DESCRIPTION OF THE DRAWING (S)

FIGURE 1 is an isometric view of the boring bar and boring bar holder according to the invention.

FIGURE 2 is a front view of a boring bar and boring bar holder according to another embodiment of the invention. FIGURE 3 is a front view of the boring bar and boring bar holder similar to Figure 2.

FIGURE 4 is a side view of the bar and holder similar to Figures 2 and 3.

FIGURE 5 shows a schematic view of a boring bar showing the force vectors encountered in normal operation.

FIGURE 6 shows a lateral cross sectional view of a boring bar according to the invention.

FIGURE 7 is a cross sectional view taken on line 7-7 of Figure 8 with the boring bar removed. FIGURE 8 shows a side view of a conventional boring bar and boring bar holder. DESCRIPTION OF THE PREFERRED EMBODIMENT (S )

Now with more particular reference to the drawings, Figure 1 shows a combination tool 10 made up of boring bar 12 and a boring bar holder 14. Boring bar 12 has elongated generally cylindrical body 16. First flat surface 24 and second flat surface 26 are formed on the outside of boring bar 12 and extend axially thereon. First flat surface 24 and second flat surface 26 of boring bar 12 are arranged in relation to each other in the form of a "V". First flat surface 24 and second flat surface 26 of boring bar 12 are disposed at forty-five degrees to a vertical center line of boring bar 12 and disposed at ninety degrees to each other. Boring bar 12 also has cylindrical surface 32 that joins flat surfaces 24,26.

Boring bar holder 14 has two flat surfaces disposed in "V" relation to each other which engage surfaces 24,26 of boring bar 12 and are disposed at ninety degrees.

A suitable cutting tool 25 will be attached to tool end 20 of boring bar 12 in a conventional manner familiar to those skilled in the art. Journal member 28 has cylindrical surface 31 which engages boring bar 12. Cylindrical surface 31 of journal member 28 has a larger radius of curvature than the radius of cylindrical surface 32 of boring bar 12. Since cylindrical surface 31 has a larger radius than cylindrical surface 32, cylindrical surface 31 makes line contact with cylindrical surface 32 Now with reference to the embodiments of the invention shown in Figures 2 and 3, tool 10 in each case is made up of boring bar 12 and boring bar holder 14.

The embodiment of the invention shown in Figures 2 and 3 have boring bar 12 having cylindrical body 16 which is generally cylindrical in cross section having first flat surface 24 and second flat surface 26 disposed at ninety degrees to each other. A suitable cutting insert will be fixed to tool end 20 in a conventional manner. Journal member 28 will be held to boring bar holder 14 by a suitable fastening means. Journal member 28 is in the form of a bar having a flat lower surface 29 which engages the cylindrical body of boring bar 12 making line contact thereby exerting a force that will be transmitted evenly to surfaces 24,26, thereby holding boring bar 12 in positive alignment.

The embodiment of Figure 3 differs from Figure 2 by recess 36 in clamping bars 30. Recess 36 has flat bottom 34 which engages cylindrical surface 32 of boring bar 12.

The embodiment shown in Figure 4, is a side view of boring bar 12 and boring bar holder 14. Boring bar 12 may be generally cylindrical like the boring bar in the other embodiments. Boring bar 12 is supported on boring bar holder 14. Cutting tool 25 is supported on tool end 20 of boring bar 12. First end 18 of boring bar 12 is received in boring bar holder 14 and clamping bars 30 are held by studs 33 to clamp boring bar 12 in boring bar holder 14. Boring bar 12 will be made with flat surfaces like first flat surface 24 and second flat surface 26 in the embodiment of Figures 1, 2 and 3. Clamping bars 30 will be made like clamping bars 30 in Figures 1, 2 and 3.

Figure 5 shows a diagram of forces x, y and z on boring bar 12 showing vector in the x, y and z planes. The vertical vector x is considerably greater than y and z vectors.

Figure 6 shows a cross sectional view of the boring bar according to the invention showing flat surfaces 25,26 being disposed t ninety degrees to each other. Figure 7 shows boring bar holder 14 of a type according to the prior art having cylindrical bore 46 to receive cylindrical boring bar 12 with boring bar holder 14 clamped on boring bar 12 by suitable set screw 42.

Figure 8 shows a side view of boring bar holder 14 according to the invention.

The foregoing specification sets forth the invention in its preferred, practical forms but the structure shown is capable of modification within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A boring bar and a boring bar holder; said boring bar comprising a cylindrical body having a first end and a tool end; a cutting tool is supported on said tool end; a first flat surface and a second flat surface are formed on said cylindrical body between said first end and said tool end; said first flat surface and said second flat surface being disposed at substantially ninety degrees to each other; said boring bar holder having a first flat surface and a second flat surface disposed at ninety degree to one another engaging said flat surfaces on said boring bar; a journal member engaging said boring bar with line contact on a side of said boring bar opposite said first flat surface and said second flat surface; and, a center line of said boring bar being disposed at forty- five degrees from said first flat surface and forty-five degrees from said second flat surface.

2. The boring bar and boring bar holder recited in claim 1 wherein said boring bar has a generally cylindrical surface and said journal member has a generally cylindrical surface.

3. The boring bar holder and boring bar recited in claim 1 wherein said journal member has a generally cylindrical body having said flat surfaces adjacent one end thereof.

4. A boring bar and boring bar holder comprising said boring bar holder having a "V" shaped groove therein; said groove being defined by a first flat surface and a second flat surface disposed at substantially ninety degrees to each other; said boring bar having two elongated flat surfaces disposed at substantially ninety degrees to each other forming said "V" shaped groove; said flat surfaces on said boring bar engaging said flat surfaces on said boring bar holder and a journal member engaging said boring bar with substantially line contact on a radial line passing through said center of said boring bar and through a central axis of said "V" shaped groove by said flat surfaces toward said flat surface on said boring bar support; force means for urging said bar toward said boring bar support; and, said flat surfaces on said boring bar support.

5. The boring bar and boring bar holder recited in claim 4 wherein said journal member has a cylindrical surface having a radius of curvature greater than the radius of curvature of said cylindrical body of said boring bar.