WO1998019814A1

WO1998019814A1 - End face mounted insert

Info

Publication number: WO1998019814A1
Application number: PCT/US1997/020479
Authority: WO
Inventors: Everett D. Hougen; Jeffrey S. Gill
Original assignee: Hougen Everett D; Gill Jeffrey S
Priority date: 1996-11-08
Filing date: 1997-11-07
Publication date: 1998-05-14
Also published as: AU5175898A

Abstract

An annular hole cutter (10) which includes a generally cylindrical cutter body (12) extending between two ends (16, 18) and defining an axis of rotation (14). At one end (16) is a shank (22) which is adapted for attachment to a cutter driving member. At the other end (18), the cutter body (12) has an end face (20) for receiving cutting inserts (28). Flutes (24) extend along the cutter body (12) between the two ends (16, 18) and channel chip material away from the end face (20) during cutting operations. Partially curved recesses (26) extend into the body (12) from the end face (20) and are generally parallel to the axis of rotation (14). The recesses (26) are spaced circumferentially about the end face (20). One cutting insert (28) is mounted in each recess (26) and is held in place by a fastener (30). The fastener (30) prevents the cutting insert (28) from separating from the cutter body (12) and ensures that the cutting insert (28) fits snugly into the recess (26).

Description

END FACE MOUNTED INSERT

BACKGROUND OF THE INVENTION

This application claims the benefit of U.S. Provisional Application No.

60/030,708, filed on 11/08/96.

This invention relates to a unique annular hole cutter utilizing an insert mounted in a recess in an end face of the cutting body.

Annular hole cutters cut holes in a workpiece, preferably a metal workpiece, by cutting an annular groove or kerf into the workpiece with an axial central slug of material remaining after the hole is cut. The cutting teeth of the annular hole cutter continually remove material from the bottom of this kerf in the form of chips which are discharged through flutes formed in the body of the annular cutter, generally in the exterior of the body. Experience has shown that the life and the efficiency of an annular cutter (i.e. the ease and the number of times in which it can cut holes in meatal workpieces and the finish produced by the annular hole cutter in the metal workpiece) are to a very large extent dependent upon the ability of the cutter to discharge the cut material of chips through its flutes or discharge passages. Thus, specially designed arrangements of cutting teeth, such as those in applicant's U.S. Pat. No. 5,145,296, U.S. Pat. Re. No. 33,440, and U.S. Pat. No.4,952, 102 for example, have increased the life of annular cutters by efficiently removing chip material away from the cutting teeth and preventing clogs between the cutting edges and the workpiece. Also important to the life of an annular hole cutter is the strength and durability of the cutting edges. High speed steel inserts have been used to improve the life of cutting edges. Typically, portions of the flutes extending along the cylindrical cutter body are cut away and the inserts are brazed or soldered into these cut out portions. It is difficult to machine these cut outs into the flutes due to the orientation of the flutes along the cutter body length. Thus, it is desirable to provide a cutter body with inserts that do not require the flute faces to be cut.

The cutting inserts provide the cutting edge or teeth for cutting the hole in a workpiece. It is difficult and time consuming to properly align and solder these inserts into the the flutes. An improperly aligned tooth provides an inaccurate cut and often the entire cutter body must be replaced. Thus, it is desirable to provide an annular hole cutter with inserts that are easily and accurately installed.

Once the inserts are soldered into place, they have to be resharpened from time to time during the cutting operation as the cutting edges wear to the point that they no longer are providing an efficient and accurate cut.

Resharpening the teeth on the cutting inserts is time consuming resulting in significant machining down time. Also, if one of the teeth breaks during cutting it is difficult to replace or repair. Thus, it is desirable to provide an annular hole cutter with a removable cutting insert which can quickly be replaced during cutting operations.

A still further problem with inserts soldered into place is the difficulty experienced with resharpening the tool on the jobsite. If the tool dulls, it typically must be sent to an offsite resharpening center. Normally, the jobsite requires a number of cutters to ensure that sharpened cutters are always available when needed. This is relatively expensive and when the jobsite is at a remote location, it is somewhat impractical.

Finally, another disadvantage of soldered inserts is that the number of cutting inserts or teeth is fixed. If a workpiece has several different size holes to be cut requiring cutters with different numbers of teeth, the first cutter body has to be removed and replaced with another cutter body. Thus, it is desirable to provide an annular hole cutter with easily removable cutting inserts which can be quickly removed or added such that various numbers of teeth can be used on a single cutter body. SUMMARY OF THE INVENTION

The annular hole cutter of the present invention has a generally cylindrical body having an end face and defining an axis of rotation. At least one partially curvilinear recess extends into the body from the end face. A cutting insert is mounted in the recess with a fastener. The fastener prevents the cutting insert from separating from the body during the cutting process.

The invention includes a method for replacing a worn out cutting insert with a new cutting insert for an annular hole cutter. The method including the steps of: providing an annular hole cutter having a body with an end face including at least one partially curvilinear recess extending through the body from the end face and having at least one fastener for mounting the cutting insert to the body; unfastening the fastener; removing the worn out cutting insert; and fastening the new cutting insert to the end face of the body to prevent the cutting insert from separating from the body.

The annular hole cutter overcomes the deficiencies of prior art methods by providing partially curved recesses for holding cutting inserts that extend into the end face of the body. These recesses are easily machined because they are cut in respect to the end face as opposed to being cut along the body. The inserts are easily and accurately installed with a fastener and can be quickly removed and replaced minimizing machine down time. Finally, the inserts can be removed easily from or added to the body to provide flexibility in the number of cutting inserts used on a single annular hole cutter.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: Figure 1A is a side view of a annular hole cutter utilizing the subject invention;

Figure IB is a is a top view of the annular hole cutter shown in Figure 1A; Figure 2A is an enlarged side view of the annular hole cutter shown in

Figure 1A;

Figure 2B is an enlarged cutaway showing a recess;

Figure 3A is a magnified side view of a cutting insert and fastener;

Figure 3B is a top view of the cutting insert and fastener shown in Figure 3A;

Figure 4 A is a partial top view of the end face of the body;

Figure 4B is partial side view showing the cutting edges; and

Figure 4C is a partial cut away showing a fastener and an insert in a recess.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

As shown in Figures 1A and IB, an annular hole cutter is generally shown at 10. The annular hole cutter 10 includes a generally cylindrical body 12 which defines an axis of rotation 14 and extends between a first end

16 and a second end 18. Adjacent to the second end 18 of the cutter 10 is an end face 20. The end face 20 defines an end face plane which intersects the axis of rotation 14.

A shank 22 extends outwardly from the first end 16 of the body 12, opposite from the end face 20, for attachment to a cutter driving source (not shown). The cutter driving source is well known in the art and drives the body 12 such that it rotates about its axis of rotation 14 during cutting operations. At least one flute 24 extend along the body 12 between the first 16 and second 18 ends. The flute 24 channels chip material away from the end face 20 during cutting. A plurality of partially curvilinear recesses 26 extend into the body 12 from the end face 20. A cutting insert 28 is mounted in each of these recesses 26 by at least one fastener 30. These recesses 26 and inserts 28 are circumferentially spaced about the end face 20 as shown in Figure IB. The fastener 30 for mounting each of these cutting inserts 28 prevents the insert 28 from separating from the body 12 and fixes the cutting insert 28 with respect to the fastener 30. Although four (4) inserts 28 are shown in Figure IB, it should be understood that the number of cutting inserts 28 can vary depending upon the size of the hole to be cut and the material of the workpiece. As shown in Figures 2A and 2B, each recess 26 is similar to a rounded pocket and is defined by a length L, a depth D, and a width W. The length L of the recess 26 is coplanar with the end face plane. The depth D of the recess 26 is non-coplanar with the end face plane. One of the important characteristics of the recess 26 is that its length L is greater than its depth D. The recess 26 includes a curved back wall 32 which engages a trailing edge 34 of the insert 28 during cutting. Preferably, the the trailing edge 34 is rounded to snugly engage the back wall 32 of the recess 26.. Because the recess 26 is located at the end face 20 of the body 12 with its length L being greater than its depth D, it is easily machined. Also, due to the location of the recess 26, it is easy to fasten and unfasten the removable cutting inserts 28.

The cutting insert 28 includes at least one cutting edge 36 or tooth over which the cutting force is distributed. While a single cutting edge 36 is referenced in this application it should be understood that a tooth on each insert 28 can be comprised of various cutting edges 36 intersecting each other at various angles. This reflects the complex tooth design that exists in this art for efficiently removing chip material away from the cutting edges 36 and preventing clogs between the cutting edges 36 and the workpiece. Thus, while each insert 28 is referenced as having a single tooth or a single cutting edge 36, it should be understood that this tooth can include a plurality of cutting edges 36. As shown in Figures 3 A and 3B, the fastener 30 includes a head portion 38 and a body portion 40 depending from the head portion 38. The head portion 38 has a larger cross sectional area than the body portion 40. The recess 26 includes a first aperture 42 which is sized appropriately to receive the body portion 40 of the fastener 30. Preferably the first aperture

42 and the fastener 30 are threaded such that the fastener 30 can quickly and easily be threaded into the first aperture 42. While a threaded fastener 30 is disclosed, it should be understood that other fasteners and fastening methods can be used to secure the insert 28 to the end face 20. The important feature is that the fastener 30 allows the insert 28 removed and replaced.

The head portion 38 of the fastener 30 is defined by a diameter "d" and a length "1." The length "1" of the head 38 must be less than the depth D of the recess 26 so that the fastener 30 does not interfere with the cutting edge 36 during the cutting operation. Also, the cutting edge 36 must extend outwardly from the recess 26 such that the back wall 32 of the recess 26 does not interfere with the cutting edge 36 during cutting.

As shown in Figures 4A, 4B, and 4C, the cutting insert 28 includes a passage 44 or second aperture through which the body 40 of the fastener 30 extends. This passage 44 has a greater cross sectional area than the body portion 40 of the fastener 30. However, the head portion 38 of the fastener

30 must have a greater cross sectional area than the passage 44 such that the insert 28 is prevented from separating from the body 12. In other words, diameter "d" of the head portion 38 must be greater than the diameter of the passage 44 in the insert 28. The cutting inserts 28 can be classified into two different sets. The first set of cutting inserts 46 includes a first set of grooves 48 while the second set of cutting inserts 50 includes a second set of grooves 48. The grooves 48 are cut into the cutting inserts 46, 50 such that the length of the grooves 48 is coplanar with the end face plane. The first set of grooves 48 has a different orientation than the second set. The orientation of the grooves 48 refers to the spacing and placement of the grooves 48 across the face 52 of the cutting insert 46, 50. In one orientation, grooves 48 are placed toward the outer periphery of the end face 20 while in the other configuration the grooves 48 are additionally placed toward the center of the end face 20. While in the preferred embodiment, two different types of cutting inserts 46, 50 are used, it should be understood that only one type or more than two types of cutting inserts could be used.

The grooves 48 are for splitting chips created during cutting. The first set of grooves 48 is different than the second set of grooves 48 so that the chips will be sufficiently split into smaller pieces such that they do not become jammed between the cutting edge 36 and the workpiece. When material does become jammed, it makes the cutter body 12 and cutting edges 36 work harder which decreases the life of the cutting edges 36. The first 46 and second 50 sets of cutting inserts alternate around the end face 20.

As shown in Figure 4C, the fastener 30 defines a first centerline 54 and the passage 44 defines a second centerline 56. The first centerline 54 is parallel to but not collinear with the second centerline 56 during cutting. The offset between the first 54 and second 56 centerlines ensures that there is a snug fit between the insert 28 and the back wall 32 of the recess and prevents the insert 28 from exerting cutting forces on the fastener 30 as discussed in detail below. Optionally, a cam screw could be used in place of providing an offset such that when cammed, the insert 28 fits snugly against the back wall 32.

When the cutting process is initiated, the cutting edge 36 receives the cutting force or load. This load is transferred to the back wall 32 due to the engagement between the trailing edge 34 of the insert 28 and the back wall 32 of the recess 26. This engagement between the trailing edge 34 and the back wall 32 provides support for the cutting edge 36 during the cutting process.

The passage 44 in the cutting insert 28 includes an inner surface 58 which surrounds the body 40 of the fastener 30. During the cutting process, as the trailing edge 34 of the insert 28 engages the back wall 32 of the recess

26, the inner surface 58 of the passage 44 does not contact the body 40 of the fastener 30. Not only does the engagement between the trailing edge 34 and the back wall 32 provide support for the cutting edge 36, it also prevents the inner surface 58 of the passage 44 from contacting the fastener 30. Thus, there is a small gap 60 between the inner surface 58 of the passage 44 and the fastener 30 when the trailing edge 34 of the insert 28 engages the back wall 32 of the recess 26 during cutting. This means that the fastener 30 is not subject to any of the cutting force or load during the cutting process. Only the cutting edge 36 and the back wall 32 of the recess 26 receive this cutting force. Thus, it is unlikely that the fastener 30 will break or become damaged during cutting operations. This will insure that fasteners 30 can quickly and easily be removed to change out a worn cutting insert 28 and replace it with a new insert 28.

The invention includes a method for replacing a worn out cutting insert 28 with a new cutting insert 28 for an annular hole cutter 10 having a body 12 with an end face 20 including at least one partially curvilinear recess 26 extending through the body 12 from the end face 20 and having at least one fastener 30 for mounting the cutting insert 28 to the body 12. The method includes the steps of: unfastening the fastener 30; removing the worn out cutting insert 28; and fastening the new cutting insert 28 to the end face 20 of the body 12 to prevent the cutting insert 28 from separating from the body 12.

Additional steps include positioning the new cutting insert 28 against a back wall 32 of the recess 26; aligning a first aperture 42 in the recess 26 with a second aperture 44 in the new cutting insert 28; and defining a first centerline 54 of the fastener 30, defining a second centerline 56 for the second aperture 44, and offsetting the first centerline 54 from the second centerline 56, toward the back wall 32 of the recess 26, before fastening the new cutting insert 28 to the end face 20 of the body 12.

Preferably the cutting insert 28 is made from standard 8620 steel material or any other tool steel or high speed steel known in the art. The material is preferably heat treated and case hardened to D30. A preferred embodiment of this invention has been disclosed, however, a worker of ordinary skill in the art would recognize that certain modifications come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims

CLAEVIS

We claim:

1. A method for replacing a worn out cutting insert with a new cutting insert for an annular hole cutter having a body with an end face including at least one partially curvilinear recess extending through the body from the end face and having at least one fastener for mounting the cutting insert to the body; the method including the steps of:

1) unfastening the fastener; 2) removing the worn out cutting insert;

3) fastening the new cutting insert to the end face of the body to prevent the cutting insert from separating from the body.

2. A method as set forth in Claim 1 further including the step of positioning the new cutting insert against a curved back wall of the recess before fastening the new cutting insert to the end face of the body.

3. A method as set forth in Claim 2 further including the step of aligning a first aperture in the recess with a second aperture in the new cutting insert before fastening the new cutting insert to the end face of the body.

4. A method as set forth in Claim 3 further including the steps of defining a first centerline of the fastener, defining a second centerline for the second aperture, and offsetting the first centerline from the second centerline, toward the back wall of the recess, before fastening the new cutting insert to the end face of the body.

5. An annular hole cutter comprising a generally cylindrical body having an end face and defining an axis of rotation; at least one partially curvilinear recess extending into said body from said end face; a cutting insert mounted in said recess; and a fastener for mounting said cutting insert in said recess to prevent said cutting insert from separating from said body.

6. An annular hole cutter as set forth in Claim 5 wherein said recess includes a curved back wall for engaging said insert.

7. An annular hole cutter as set forth in Claim 5 wherein said fastener includes a head portion and a body portion depending from said head portion, said head portion having a larger cross sectional area than said body portion.

8. An annular hole cutter as set forth in Claim 7 wherein said cutting insert includes a passage through which said body of said fastener extends, said passage having a greater cross sectional area than said body portion of said fastener.

9. An annular hole cutter as set forth in Claim 8 wherein said fastener defines a first centerline and said passage defines a second centerline, said first centerline being parallel to but not collinear with said second centerline during cutting.

10. An annular hole cutter as set forth in Claim 5 wherein said recess includes a back wall and said cutting insert includes a curved trailing edge for engaging said back wall during cutting.

11. An annular hole cutter as set forth in Claim 10 wherein said cutting insert includes a passage with an inner surface for surrounding but not NOT TAKEN INTO CONSIDERATION

FOR THE PURPOSES OF INTERNATIONAL PROCESSING

a plurality of partially curved recesses extending into said body from said end face; a cutting insert mounted in each of said recesses; and a fastener for mounting each of said cutting inserts in its respective recess to prevent said cutting insert from separating from said body during cutting while allowing said cutting insert to be removed and replaced after said cutting insert has worn.

19. An annular hole cutter as set forth in Claim 18 wherein each of said recesses includes a curved back wall for engaging said insert.

20. An annular hole cutter as set forth in Claim 18 wherein said fasteners are not subject to any cutting forces.

21. An annular hole cutter as set forth in Claim 18 wherein said cutting inserts include at least one groove for splitting chip material during cutting.

22. An annular hole cutter as set forth in Claim 21 wherein said cutting inserts are comprised of a first set of cutting inserts with grooves and a second set of cutting inserts with grooves, said first set having a different orientation of grooves than said second set.

23. An annular hole cutter as set forth in Claim 22 wherein said first and second sets of cutting inserts alternate around said end face.

24. An annular hole cutter as set forth in Claim 18 wherein said recess is defined by a length, a width, and a depth, said length being greater than said depth.