CA1082497A - Helical broaching tool for curved surfaces - Google Patents

Helical broaching tool for curved surfaces

Info

Publication number
CA1082497A
CA1082497A CA288,147A CA288147A CA1082497A CA 1082497 A CA1082497 A CA 1082497A CA 288147 A CA288147 A CA 288147A CA 1082497 A CA1082497 A CA 1082497A
Authority
CA
Canada
Prior art keywords
face
recesses
arcuate
broaching tool
broaching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA288,147A
Other languages
French (fr)
Inventor
Sylvester E. Proulx
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JP Tool Ltd
Original Assignee
JP Tool Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by JP Tool Ltd filed Critical JP Tool Ltd
Priority to CA288,147A priority Critical patent/CA1082497A/en
Priority to SE7807174A priority patent/SE439606B/en
Priority to IT24951/78A priority patent/IT1096039B/en
Priority to FR7820066A priority patent/FR2405109A1/en
Priority to GB7829188A priority patent/GB2005170B/en
Priority to AU38048/78A priority patent/AU525815B2/en
Priority to JP8761178A priority patent/JPS5454386A/en
Priority to DE19782832469 priority patent/DE2832469A1/en
Priority to US06/040,377 priority patent/US4277207A/en
Application granted granted Critical
Publication of CA1082497A publication Critical patent/CA1082497A/en
Expired legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23DPLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
    • B23D43/00Broaching tools
    • B23D43/02Broaching tools for cutting by rectilinear movement
    • B23D43/04Broaching tools for cutting by rectilinear movement having inserted cutting edges

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Milling, Broaching, Filing, Reaming, And Others (AREA)
  • Milling Processes (AREA)
  • Food-Manufacturing Devices (AREA)

Abstract

HELICAL BROACHING TOOL FOR CURVED SURFACES

Abstract of the Disclosure A broaching tool is described having an elongated tool body with an arcuate face of preferably half-round configuration. A plurality of recesses are formed on the arcuate face, each having a flat bottom face inclined in-wardly and rearwardly within 1 - 15° of coincidence with the longitudinal axis of the body and an arcuate abutment wall perpendicular to and rearwardly surrounding the flat bottom face. These recesses are arranged in helical paths of increasing diameter in a rearward direction to form a series of spaced helical rows. Each recess contains a rotatably indexable cylindrical cutter disc. This con-figuration of broach has the advantages of providing excellent chip clearance between the cutter and also providing a uniform load on the tool during broaching.

Description

~Q8;~497 BACKG~OUND OF THE INVENTION
1. Field of the invention This invention relates to a novel broaching tool of the type typically used to produce a round hole or a semi-circular hole.
2. Description of the prior art Broaching is a machining process whereby one or more cutters with a series of teeth are pushed or drawn entirely across a workpiece and is analogous to single-stroke filing. Broaching is typically carried out onmanually-operated presses, on pull-screw machines or on hydraulically actuated broaching machines or presses.
The broach has teeth which increase in height towards one end and is typically held in the screw socket of a broaching machine screw or ram by a taper cotter. Usually the first few teeth on the broach are low to permit the small end of the tool to pass through a hole in the work-piece, while the intermediate teeth re ve most of the metal and the last few teeth finish the surface to size.
The typical broaching tool presently in use is in the form of an elongated body having a plurality of spaced annular ribs generally transverse to the longitudinal body of the axis. A series of titanium carbide teeth are , brazed onto ~ide walls of these ribs in a position per-pendicular to the longitudinal body axis. Each of these teeth has a curved upper cutting edge. Of course, when these cutter teeth become worn, it becomes a very expensive proposition to remove the worn teeth and then braze new cutter teeth into position against the ribs. Also, because each cutting edge engages the workpiece at sub-stantially 90, it will be appreciated that immense stresses . ~

are placed on the tool and the cutter teeth particularly when broaching metals.
In Applicants U.S. Patent 3,946,472, issued March 30, 1976, there is described a broaching tool in which cutter teeth in the shape of buttons or discs have been successfully used for the broaching of concave sur-faces. This had the unique feature of being able to make use of the angular positioning of the discs so as to form a smoothly curving contoured surface. Although this re-presented a great improvement over the previous broachingtools, it did have some problems. Thus, for most broaching tools it was necessary to provide chip relief gaps between the rows of cutter discs so that chips formed would be dispersed easily and not become jammed between cutter discs thereby creating difficulties. Moreover, because the cutter discs were arranged in parallel rows, very heavy instantaneous loads were placed on the tool as each row came into engagement with the workpiece.
It is , therefore, the object of the present invention to provide an improved configuration of broaching tool for the broaching of concave surfaces in which the chip dispersal is simplified and the tool is provided with a substantially uniform loading during operation.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a novel broaching tool comprising an elongated tool body having an arcuate face of at least 45. A
, plurality of recesses are formed in this arcuate face, each recess having a flat bottom face inclined inwardly and rearwardly within 1-15 of coincidence with the longitudinal axis of the body and an arcuate abutment wall 108'~497 perpendicular to and rearwardly surrounding the flat bottom face. The recesses are arranged in helical paths of an increasing diameter in a rearward direction about the tool body arcuate face to form a series of spaced helical rows. The recesses of each row are staggered circumferentially with respect to the recesses of the next adjacent row whereby paths of successive recesses partially overlap. Cylindrical cutting discs are mounted in the recesses, each disc having an end face providing a cutting edge disposed about the periphery of the end face and being rotatably indexable about its longitudinal axis to bring successive portions into cutting position.
The arcuate face forms an arc of at least 45 and usually at least 90. For a typical half round broach the arc will be in excess of 180 and it may even ; form a full cylindrical broach. The helical path normally defines an angle of about 5 to 95 with respect to the longitudinal axis of the body and a typical tool has a helical angle in the order of about 15 to 45.
The helical paths are of increasing diameter in a rearward direction so as to produce a progressively larger hole as the broach is moved through the workpiece or the workpiece over the broach. This diameter difference is normally quite small and may typically be in the order of 0.004 ~nch between rows.

The angle of the cutter discs with respect to - the longitudinal axis of the body can be varied within the range of about 1-15. By setting the series of small round cutting discs at a small angle with respect to the longitudinal axis of the body, the cutting edges of the cutter discs thereby form small arcs of a much larger -circle than the diameter of the discs themselves. This, combined with the overlapping of the successive cutters due to the staggering arrangement of cutters in successive rows,results in the depth of grooves formed in the finished surface being very small. Normally, the discs are arranged to broach a hole having a radius at least three times the radius of the individual cutter discs.
Certain preferred embodiments of the present invention will now be illustrated by the attached drawings in which:
Figure 1 is a side elevation of one embodiment of the novel broaching tool;
Figure 2 is a top plan view of the broaching tool shown in Figure l;
Figure 3 is a cross section through row 1 of the tool of Figure l;
Figure 4 is a cross section through row 2 of the tool of Figure l; and Figure 5 is an exploded detailed view of a cutting disc and socket.
The particular broach illustrated in the - drawings is known as a half-round broach. It has an elongated tool holder body portion 20 having a bottom -- spline 21 extending along the length thereof for retaining the tool in a tool holder. The tool is held rigidly in place in the holder by the mounting screws 22.
At the lower edges of the cylindrical surface are provided a series of pockets 23 and these serve as ;, 30 interlocks with adjacent flat broaches which may be used 1, in conjunction with the half-round broach.
_ 5 _ -.

108~497 A series of cutter discs 24 are mounted in sockets 25 in the cylindrical surface. Each of these sockets has a flat bottom face 26 which is inclined at a small angle of typically about 11 to the longitudinal axis of the body portion 20 and the socket also has a semi-circular abutment wall 27 which is perpendicular to the bottom face 26. Extending into the body portion 20 through face 26 is a tapped h~le 32.
Each cutting disc 24 has a cylindrical wall 29 and end faces 28. A hole 31 is formed axially through the insert with a conical countersink 30. The cutting disc is typically made from tungsten carbide. It is held in position by means of a threaded screw 33 which has a conical head portion which mates with the countersink and the cutting disc and the head of the screw includes a -socket 34 for receiving a wrench. When the cutting disc has been placed in position in the socket 25 and the screw tightened, the insert is pressed firmly against the abutment wall 27. Thus, when the broach is in operation the forces on the cutting inserts are fully carried by the abutment walls 27 rather than by the screws themselves.
With this arrangement, it will be seen that only about one-quarter of the cutting edge of the cutter discs is in use at one time. This means that as the portion ~ in use becomes dulled, the screws 33 can be loosened and the cutter discs can then be rotated sufficiently to present fresh cutting edge portions, after which the screws are again tightened. The result is that as many as four cutting edge portions may be available on one face of a cutter disc. Furthermore, it is possible to make the discs reversible so that another four cutting edge portions 108'~497 may be available on the reverse face. In this way as many as eight fresh cutting edge portions may be obtainable from a single cutting disc.
A typical cutter disc may have a diameter in the range of about 3/8 inch to about 1 inch and these are used in cutting holes having a diameter of at least 1 inch.
In Figure 1 eight helical rows of cutting discs are shown and these are indicated as rows one to eight.
1~) Figure 3 shows the positioning of the cutter discs for what are designated as rows 1, 3, 5 and 7 in Figure 1 while Figure 4 is a cross-section showing the position of the cutter discs for the rows designated as 2, 4, 6 and 8 in Figure 1. Particularly from Figures 3 and 4 it becomes evident that the successive rows of cutting inserts are positioned in a circumferentially staggered manner. Thus, the axes of the cutting inserts of row 2 are positioned midway between the axes of the inserts of row 1 while the inserts of row 3 are in alignment with the inserts of row 1. The diameter typically is increased by an amount of about 0.004 inch from one row to the next following row. However, it is also possible to have two or re adjacent rows of the same diameter, followed by two or more rows of increased equal diameter. It is also ~ sometimes desirable to have the last cutting insert of one row at the same elevation as the first cutting insert of the next following row.
One of the advantages of this helical con-figuration is that specific chip gaps are not necessary since the spacing between cutting discs in the helical configuration is increased thereby permitting easier 108;~497 flow of chips between cutters. The second and most im-portant advantage of the helical configuration is that during operation some of the discs will always be under load. This overcomes any tendency of impact as successive rows of cutting discs come into engagement with the work-piece. This feature will be evident from Figures 1 and 2 so that each cuttinq disc of each row comes into engage-ment with the workpiece successively and during engagement with the last cutting disc of one row, the workpiece is already coming into engagement with the first cutting disc of the next row. This greatly decreases the tendency of damage to the broach as well as possible breakage of the workpiece being broached from impact.
While the above preferred embodiment illustrates a screw connection for mounting the cutting inserts in the sockets, it will be readily apparent to those skilled in the art that many other kinds of mounting means are possible. Thus, wedging pins, etc. can be used.
It will also be apparent to those skilled in the art that although a half-round broach is illustrated, , similar types of broaches forming arcs of less than a semi-circle or as much as a full circle are within the scope of the present invention.

Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A broaching tool comprising an elongated tool body having an arcuate face of at least 45°, a plurality of recesses formed in said arcuate face, each said recess having a flat bottom face inclined inwardly and rearwardly within 1 - 15° of coincidence with the longitudinal axis of the body and an arcuate abutment wall perpendicular to and rearwardly surrounding said flat bottom face, said recesses being arranged in a helical path of increasing diameter in a rearward direction about said tool body arcuate face to form a series of spaced helical rows with the recesses of each row being staggered circumferentially with respect to the recesses of the next adjacent row whereby the paths of successive recesses partially overlap and cylindrical cutter discs mounted in said recesses, each disc having an end face providing a cutting edge disposed about the periphery of the end face and being rotatably indexable about its longitudinal axis to bring successive cutting portions into cutting position.
2. A broaching tool according to claim 1 wherein the helical path defines an angle of about 5° to 95° with respect to the longitudinal axis of the tool body.
3. A broaching tool according to claim 2 wherein the arcuate face containing the cutter discs forms an arc of at least 90°.
4. A broaching tool according to claim 2 wherein the arcuate face containing the cutter discs forms an arc of at least 180°.
5. A broaching tool according to claim 2 wherein the arcuate face has an increasing diameter in the rearward direction.
CA288,147A 1977-10-05 1977-10-05 Helical broaching tool for curved surfaces Expired CA1082497A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
CA288,147A CA1082497A (en) 1977-10-05 1977-10-05 Helical broaching tool for curved surfaces
SE7807174A SE439606B (en) 1977-10-05 1978-06-22 SCREW SHAPE BROCHENING TOOL FOR CROCHET SURFACES
IT24951/78A IT1096039B (en) 1977-10-05 1978-06-26 HELICAL PITCHER FOR CURVED SURFACES
FR7820066A FR2405109A1 (en) 1977-10-05 1978-07-05 HELICOIDAL BROACHING TOOL FOR CURVED SURFACES
GB7829188A GB2005170B (en) 1977-10-05 1978-07-07 Helical broaching tool for curved surfaces
AU38048/78A AU525815B2 (en) 1977-10-05 1978-07-14 Broaching tool
JP8761178A JPS5454386A (en) 1977-10-05 1978-07-17 Cutting tool
DE19782832469 DE2832469A1 (en) 1977-10-05 1978-07-24 BROACHING TOOL
US06/040,377 US4277207A (en) 1977-10-05 1979-05-18 Helical broaching tool for curved surfaces

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA288,147A CA1082497A (en) 1977-10-05 1977-10-05 Helical broaching tool for curved surfaces

Publications (1)

Publication Number Publication Date
CA1082497A true CA1082497A (en) 1980-07-29

Family

ID=4109703

Family Applications (1)

Application Number Title Priority Date Filing Date
CA288,147A Expired CA1082497A (en) 1977-10-05 1977-10-05 Helical broaching tool for curved surfaces

Country Status (8)

Country Link
JP (1) JPS5454386A (en)
AU (1) AU525815B2 (en)
CA (1) CA1082497A (en)
DE (1) DE2832469A1 (en)
FR (1) FR2405109A1 (en)
GB (1) GB2005170B (en)
IT (1) IT1096039B (en)
SE (1) SE439606B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7213623B2 (en) * 2004-01-20 2007-05-08 Shinn Rickey D Stump cutting device with load-distributing tooth sockets
DE102007008081A1 (en) * 2007-02-17 2008-08-21 Hartmetall-Werkzeugfabrik Paul Horn Gmbh Impact tool, in particular grooving tool

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2730793A (en) * 1953-10-21 1956-01-17 Nat Broach & Mach Broaching tool
US3262183A (en) * 1964-09-25 1966-07-26 Cincinnati Milling Machine Co Broaching tool
GB1140841A (en) * 1965-01-24 1969-01-22 Production Engineering Res Ass Improved cutting tool
GB1303118A (en) * 1970-07-21 1973-01-17
US3946472A (en) * 1975-01-22 1976-03-30 J. P. Tool Limited Broaching tool

Also Published As

Publication number Publication date
DE2832469A1 (en) 1979-04-12
FR2405109A1 (en) 1979-05-04
JPS5761529B2 (en) 1982-12-24
IT7824951A0 (en) 1978-06-26
GB2005170B (en) 1982-04-15
AU3804878A (en) 1980-01-17
FR2405109B1 (en) 1984-06-29
SE439606B (en) 1985-06-24
SE7807174L (en) 1979-04-06
IT1096039B (en) 1985-08-17
JPS5454386A (en) 1979-04-28
GB2005170A (en) 1979-04-19
AU525815B2 (en) 1982-12-02

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Legal Events

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