WO1993020972A1

WO1993020972A1 - Arcuate seat tool holders and inserts

Info

Publication number: WO1993020972A1
Application number: PCT/AU1993/000155
Authority: WO
Inventors: George Nagy Horty
Original assignee: Minister Trading Co. Pty. Ltd.
Priority date: 1992-04-16
Filing date: 1993-04-07
Publication date: 1993-10-28
Also published as: AU1494392A

Abstract

The invention is a cutting tool insert and carrier assembly whereby a cutting insert (3) is releasably mounted to carrier (2) by insertion and subsequent rotation of a part circular mounting formation of insert (3) into a complementary recess (9) of carrier (2).

Description

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TITLE: ARCUATE SEAT TOOL HOLDERS AND INSERTS

TECHNICAL FIELD

This_^ invention relates to cutting tools for metal and wood. Although the invention has been developed primarily for applications where cutting tools are used in a relatively narrow groove, such as in the case of metal cutting, parting off tools, wood cutting chain saws, circular saw blades and the like but is also applicable in applications such as in metal cutting side and face cutters and large ripping cutters as used in tunnel boring and mining industry.

BACKGROUND ART

A wide variety of cutting tools for metal, wood and other materials utilise hardened cutting tips formed from materials such as tungsten carbide and the like. Whilst these tools have excellent properties as cutting edges, they are normally too expensive or unsuitable for use in forming the body of the cutting tool, For this reason a small insert of hardened material is usually secured to a holder or other carrier made from a suitable material such as high speed steel. Examples include parting off tools where a cutting tool insert is fitted into a holder, chain saw blades and circular saw blades where hardened inserts are brazed to each link of chain or tooth of saw respectively, metal side and face cutters which use a removeable insert normally held in place by a locking screw or the like and tunnel boring and mining cutters and rippers. The present art involves having a large segment provided with holes suitable for bolting onto cutter body, the said segment is further provided with a pad onto which large carbide teeth are silver soldered. The worn out carbide tips are taken off their respective pads by heating process and new carbide tips are silver soldered onto pads. All of these applications suffer certain disabilities. In the case of tunnel boring and mining cutters or rippers, this invention eliminates the time consuming process of bolting large segments onto and off the cutter bodies, by having segments provided with suitable seating arrangements for the secure holding of an exchangeable cutting or ripping insert allowing the said segment to be permanently bolted onto cutter body.

At present the only carbide tipped chain saws on the market are the so called brazed carbide chain saws in which carbide tips are permanently brazed to the chain saw segments. The drawback of the above type of chain saw chains is that they have to be resharpened in a specialist shop and if one tooth breaks or chips it has to be replaced by brazing another carbide tip into its place. Generally at least one spare chain is needed if work is to be carried on without interruption. A similar exercise is needed in the case of carbide tipped circular saws.

This invention is directed to the elimination of brazing the carbide tips to the chain or the need of replacing the entire chain when it is worn by enabling the operator to change one or all the cutting teeth, by changing out the worn inserts (cutting teeth) and inserting new ones, generally by the simple turn of an inserting tool .

The most widely used parting off tools used at present, are those which use a so called throw away carbide insert. The insert in one size is typically 3.5mm thick, 12mm long, measures approximately 9mm wide at front end (the cutting edge) and approximately 6mm wide at the other end. Thus the long sides form an included angle of approximately 12 degrees. Along the surfaces which form the 12 degree angle run angular grooves, central to the 3.5mm thickness.

The parting off tool holder is of approximate rectangular shape, typically 3mm by 25mm by 130mm long. At one end the slot is cut through the side of this blade coinciding in shape to the 12 degree included angled sides of the previously described carbide insert and generally sloping downwardly at approximately 15 degrees to the longitudinal extent of the holder. The above slot is 4-5mm longer than the carbide insert. The top and bottom surfaces are of a shape complementary to the angular grooves in the carbide insert. When the carbide insert is offered to the slot in the blade, it will go into the slot approximately 10mm before it stops by wedging itself in longitudinally and laterally. It is recommended that after inserting the carbide in insert into the slot in the blade by hand pressure, a slight knock be applied to the front of the insert so that it will wedge itself into its seat more firmly. This additionally movement into the slot is approximately 1mm, and is allowed by the virtue of the elasticity of the metal above the slot, which is much narrower in section than the metal below the slot. Thus the section of metal immediately above the carbide insert acts as a clamp, forcing the insert downwards into its seat.

The problem, although rare, with the above described tool is, that they require a slight knock at the front face to urge it deeper into a mating position secure enough for cutting. Since all carbide materials are brittle by nature the inserts may be chipped or damaged when knocking it into working position.

Regarding chain saws and circular saws there is a considerable safety concern about removable inserts since any such insert must be effectively incapable of being displaced during operation of the saw.

It is an object of this invention to provide a cutting tool insert and carrier assembly which will overcome one or more of the foregoing disadvantages. As used in the specification a "carrier" is intended to refer to any holder, saw blade, or other item used to carry a hardened cutting tip.

DISCLOSURE OF THE INVENTOR

The invention consists in a cutting tool insert and carrier assembly comprising: an open sided mounting recess of a part circular cross-section formed in said carrier, the cross-section being substantially defined by the major arc of a circle, said arc subtending more than 180 degrees such that the dimension of the open side is less than the diameter of the circle; and a complementary mounting formation on said insert, said mounting formation including a first portion adapted to engage the recess and being of complementary part circular cross-section and an adjacent second portion defining a surface less than a radius distant from the centre of said circle to provide a cross-sectional dimension of said mounting formation less than the dimension of the open side of said mounting recess to facilitate insertion of said mounting formation into said recess and subsequent engagement of said first portion with the recess surface by rotation.

Preferably, the major arc of the circle subtends an angle of between 200 degrees and 250 degrees.

More preferably, the major arc of the circle subtends an angle of between 225 degrees and 232 degrees.

It is also preferred that the radius of the part circular first portion of the mounting formation is slightly greater than that of the recess so as to provide an interference fit. Most preferably, the interference is approximately l/500th to 1/lOOOth of the diameter of the recess.

In a preferred configuration, the second adjacent portion of the mounting forms a chord to the part circular cross-section.

Because the mounting formation has a cross-sectional dimension which is less than the opening in the recess the tool can be readily presented to the recess and then driven into engagement by rotation by any suitable means. In one preferred configuration, an Allen key aperture is provided in the insert for this purpose. Alternatively, other purpose built tools can be used.

It will further be apparent that because configuring the assembly such that rotation of the insert corresponds to the normal force exerted on the tool during cutting, a simple stop is sufficient to accurately locate the cutting tip of the insert. The insert is preferably held in position laterally by complimentary profiles of the recess and mounting formation. This can, for example, take the form of a complementary part circular groove and ridge arrangement. Alternatively, angular configurations are possible.

In one preferred configuration the stop can be formed by any suitable protruberance on either the mounting formation or recess so as to provide a limit to the amount of rotational engagement that is possible.

BRIEF DESCRIPTION OF THE FIGURES

Three embodiments of this invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 shows a side elevation of a two tooth section of a circular saw assembly;

Figure 2 shows a side elevation of a section of carrier including an open sided mounting recess major arcuate recess, of the embodiment shown in Figure 1;

Figure 3 shows a cross section of Figure 2 in direction of lines 3-3;

Figure 4 is a side elevation of an insert, of the embodiment shown in Figure 1 ;

Figure 5 is a front elevation of Figure 4; Figure 6 is a top view of Figure 4;

Figure 7 shows a side elevation of an assembly of a one tooth section of a circular saw, substantially similar to the embodiment shown in Figure 1;

Figure 8 shows end elevation of an inserting tool;

Figure 9 is a side elevation of Figure 8;

Figure 10 is a sectional view of Figure 8 in direction of lines 10-10;

Figure 11 is a side view of an insert carrying a segment of a chain saw;

Figure 12 is a front view of Figure 11;

Figure 13 is a top view of Figure 11;

Figure 14 is a side view of an insert, suitable for the embodiment shown in Figure 11;

Figure 15 is a front view of Figure 14;

Figure 16 is a top view of Figure 14;

Figure 17 is a rear view of Figure 14;

Figure 18 is a side view of a parting off tool assembly;

Figure 19 is a front view of Figure 18;

Figure 20 is a top view of Figure 18; _ Figure 21 is a side view of a parting off tool holder, of the embodiment shown in Figure 18;

Figure 22 shows an end view of Figure 21;

Figure 23 is a top view of Figure 21;

Figure 24 is a cross sectional view of Figure 21 in direction of lines 24-24; Figure 25 is an enlarged view of section 25 of Figure 21;

Figure 26 shows a side view of a parting off tool insert, of the embodiment shown in Figure 18;

Figure 27 shows front view of Figure 26;

Figure 28 shows top view of Figure 26.

BEST MODE

Referring to Figures 1-10, Figure 1 shows a two-tooth section of a circular saw assembly comprising carrier 2 and cutting insert 3. Carrier 2 is generally made of carbon steel, spring steel or other suitable materials. Cutout 4 provides access for insert 3 to be introduced into open sided recess or major arcuate recess 9 shown on Figure 2, and by broken lines on Figure 1. Line 5 represents the radial clearance angle, line 6 forms the angular side of cutout 4, blending into arcuate formation 7 at the bottom of cutout 4. Curve 7 forms a peak 8 with the lower end of major arcuate recess 9, which extends over an angle of 225 degrees. Point 10 represents the intersection of wall 11 with the upper end of major arcuate recess 9. Figures 5 and 6 show groove 12, forming a major arc of about 225 degrees, in the first portion of the mounting formation of insert 3 being of cylindrical cross section and extending along the broken lines, as shown on Figure 4. Groove 12 is formed between sides 13. Cutting tooth portion 14 is outlined by leading face or rake angle 15, top rake 16, back face 17 containing groove 12 (groove 12 may be omitted from back face 17 if preferred) and base line 18. Laterally the said tooth section is bordered by sides 19 forming the side clearances of tooth 14. The intersection of leading face 15 and top rake 16 forms cutting edge 20 of the tooth. The intersection of groove 12 in back face 17 and groove 12 in major arcuate formation is point 21, as shown in Figures 4 and 6. Leading face 22 extends from base line 18 to the lower end of major arcuate sides 13 and forms point 23 with the lower end of groove 12.

As may be observed from Figure 1, forces acting on cutting edge 20 of insert 3 urge tooth portion 14 and groove 12 into closer abutment with wall 11 and centrifugal force acting on cutting insert 3 is effectively resisted by the major arc configuration of the mating surfaces. Lateral dislodgement of cutting insert 3 is prevented by sides 13 of groove 12. Cutting insert 3 is provided with 2 cylindrical apertures 24 extending through cutting insert 3 for engagement with a suitable torque key. Other means may be provided such as a slot or a hexagonal aperture.

In case of a sudden stop of the rotating saw due to stalling or jamming, the insert is prevented from rotating away from wall 11 by the considerable friction between the mating formations due to the aforesaid interference fit.

If cutting tooth portion 14 were removed and the arc of groove 12 were extended from point 21 to face 22, it would increase the angular extent of the arc in groove 12 by about 30 degrees to a total of about 255 degrees and the minimum cross sectional dimension or segmental height would be slightly less than the distance between points 8 and 10 in Figure 2, enabling insert 3 to be introduced into major arcuate recess 9 between points 8 and 10 of the 225 degree arc. As may be observed this invention utilises the aforesaid about 30 degree portion of the arc, to provide a cutting tooth 14. Consequently as the arc of arcuate recess 9 increases, it affects the useful cutter area of the insert adversely, and at an extent of 253.7 degrees the opening between the ends of 8 and 10 arcuate recess 9 is about equal to the minimum cross sectional dimension or segmental height of a mounting formation, having the same angular extent, at which point the usefulness of the invention as a cutting insert is greatly diminished but not obviated and the invention becomes useful as a locking means for doors or locking two or more objects together.

For some applications the above described assembly may be provided with locking means to prevent rotation of cutting insert 3 in a direction to extract from the arcual recess ie counterclockwise in Figure 1.

Referring to Figure 7, as the assembly is substantially the same as described in Figures 1 to 6 it will not be described in its entirety. Carrier 2 in this example is provided with a narrow arcuate slot 25 formed after the formation of cutout 4 and major arcuate recess 9 shown on Figure 2. The said slot 25 is formed at about the middle portion of major arcuate recess 9 and so positioned as to form a tapered narrow section of metal or pawl 26. The free end of pawl 26 is then deformed towards the centre of major arcual recess 9 so as to attain a natural state with its free end somewhat protruding into recess 9. The pawl is then hardened and tempered to a resilient state. In the afore described example the carrier 2 would be constructed of spring steel or other resilient metal. Insert 3 is provided with a complementary engagement formation. In this example, insert 3 is provided with an open ended semicircular cutout 27 at its periphery and said cutout 27 is so placed that when insert 3 is inserted, as shown in Figure 7, the lower side of cutout 27 is fractionally distanced from free end of pawl 26. When insert 3 in the afore described example is in the process of insertion and is rotated clockwise, the bottom surface of groove 12 in the lower portion of insert 3 displaces the free end of pawl 26 into slot 25 allowing rotation of insert and, upon insert 3 attaining its inserted position, resilient end of pawl 26 springs back into the lower side of cutout 27, beyond surface 12 of groove thus preventing anticlockwise rotation of insert 3.

An alternative to forming a pawl integrally in carrier 2 is to provide an inserted pa l, formed from a plate of spring steel. In this embodiment the major arcuate recess 9, shown on Figure 7, is provided with an arcuate cutout of the approximate length of slot 25, with substantially square ends and into this cutout the said spring steel plate, containing a pawl is inserted and secured against displacement. In the afore described assemblies, insert 3 can only be extracted from its seat with the aid of a purpose made inserting tool, as shown on Figures 8, 9 and 10. Figure 8 shows the circular end of inserting tool body 28 and within said circular end are contained two pins 29 and pin 30, spaced apart to form a mating engagement with apertures 24 and cutout 27 respectively. A portion of pin 30, protruding from body 28, is of generally semicircular form with its outer surface 31 formed in an arc to coincide with the arcuate surface and diameter of groove 12. Pin 30 is further provided with chamfer 32 extending in an arc at end of pin and surface 31, providing a lead in for pin 30, as best shown in Figure 10.

When extracting insert 3 with the afore described inserting tool , pins 29 and pin 30 are brought into partial engagement with apertures 24 and cutout 27 respectively with chamfer 32 engaging the inner edge of pawl 26. The inserting tool is then forced into full engagement and in the process displaces the free end of pawl 26 to the arcuate plane of groove surface 12 thus facilitating counterclockwise rotation and extraction of insert 3 when torsion force is applied to lever 33 shown on Figures 8 and 9.

Referring to Figure 7, in this example face 15 of insert 3 is extended to the approximate mid section of the insert forming a depression with face 22, to enable the inserting tool to be used, if desired with pin 30 occupying said depression when inserting an insert. Other methods of providing a retaining pawl are possible, but all forms need the application of an inserting tool substantially as afore described.

Referring to Figures 11 to 17, Figure 11 shows the segment 32 of a chain saw provided with an open sided or arcuate recess 33 of a major arc proportion, extending over an angle of about 225 degrees and being of cylindrical cross section. Arcuate protrusion 34 is the so called rake as known in the art and is generally 0.6mm below the height of the cutting edge. Cutout 35 between rake 34 and recess 33 is to provide partial and temporary accommodation for wood shavings. Segment 32 is bordered by front face 36 blending into arcuate formation 37. At mid section of base line 38 is cutout 39, serving as clearance for the drive. End face 41 and base line 38 blend into arc 40. Arc 42 blends into face 41 at one end with other end ending in stop formation 43. Forming a peak with lower end of arcuate recess 33 is angular wall 44. Segment 32 is provided with two riveting holes 90 spaced as is normal in the art. Figure 11 shows with broken lines, three stages of the inserting process of insert 46 into recess 33. Figures 12 and 13 show the parallel sides 45 of segment 32 and broken lines show the silhouettes of insert 46. Segment 32 as shown in Figures 11, 12 and 13 is substantially of same configuration as presently applied or known to the art, excepting features 33, 42, 43 and 44.

Referring to Figures 14 to 17, Figure 14 shows a side view of a left handed insert 46, suitable for insertion into recess 33 of Figure 11. Groove 47 being of a configuration of a major arc, extends along broken lines as shown on Figure 14. Groove surface 47 is cut into major arcuate surface 48. Groove 47 intersects with a small arc into face 59. Top clearance 49, and the rake angle 50 form cutting edge 51. Faces 54 and 56 form point 55. Sides 52 and 53 form the side clearances of cutting edge 51. The insert 4 is provided with two cylindrical cavities 57 and 58, extending somewhat beyond the mid section of insert 46, for engagement with suitable torque key.

Referring to Figure 11, at first stage of insertion, insert 46 is placed into cutout 35 in a substantially horizontal position and introduced into major arcual recess 33. At this stage point 55 of insert 46 is adjacent to peak of wall 44 of chain segment 32. At the second stage of insertion, cutting edge 51 is raised in an arc and insert 46 moves slightly deeper into major arcuate recess 33, engaging major arcuate groove 47 with cylindrical surface of recess 33, creating a narrow crescent shape aperture between groove 47 and major arcuate recess 33. The diameter of the major arcuate groove surface 47 being of an interference fit relative to that of major arcuate recess 33, insert 46 is driven into full engagement, with an appropriate torque key engaged in cavities 57 and 58 and prevented from further rotation by angular rear face 59, on Figure 14, abutting angular face of backstop 43 of segment 32 as shown on Figure 1.

Forces acting on edge 51 urge angular wall 59 to a more forceful abutment with the coincidentally formed angular face of stop 43, causing a tendency of said portion 43 to move downwardly and thus coming into a more forceful frictional engagement with arcuate groove 47. Lateral displacement of insert 46 is prevented by the close fitting sides of jnajor arcual protrusion 48 to sides 45 of segment 32.

Referring to Figures 18 to 28, Figure 18 shows a parting off tool assembly, comprising a carrier 62, with an exchangeable carbide insert 63 mounted at one end. Figures 19 and 20 show end view and top view of Figure 18, with parallel sides 71 and 72. Carrier 62 is described in more detail in Figures 21 to 25. Referring to Figure 21 carrier 62 is provided with recesses 64, in the configuration of a major arc extending over an angle of 232 degrees. Recesses 64 being identical, only one will be described. Recess 64 contains a groove of angular cross section 65, as shown in Figure 24. Carrier 62 is outlined by line 66 forming the top edge of carrier between the upper end of arcuate recess 64, line 67 forms the base of carrier 62. Extending from either end of base line in substantially vertical direction, are clearance faces 68. Angular surfaces 69 form a tool rest or stop for insert 63, as shown on Figure 21 and 25. Figure 25 shows the arcuate intersection 70 of face 69 and lower arcuate end of recess 64. Figures 22 and 23 show parallel sides 71 and 72 of carrier 62. Major arcuate recess 64 extends 52 degrees above a centre line drawn horizontally from point 70 through centre of arc, to provide a greater retaining capacity to insert 63, as shown on Figure 21.

Referring to Figures 26 to 27, Figure 26 shows a side view of insert 63. The lower portion of insert 63 is outlined by protruding major arcuate mating surfaces 73 complementary to groove surfaces 65 on Figure 24. Mating surfaces on insert 63 may be formed as a groove and conversely a protrusion in carrier 62 as in any other applications of the invention. Mating surfaces or protrusion 73 extend over an angle of over 232 degrees forming a major arcuate segment with broken lines 74 as shown on Figure 26. Top face 75 of the insert 63 extends horizontally from upper end of arcs 73 to cutting edge 71. Face 77 extends downwardly from edge 71 at a slight angle inclined towards the centre of insert 63 and forming a lower clearance face. From the end of face 77 extends face 78 inclined upwardly at an angle to coincide with face 69 as seen in Figure 18. Face 78 intersects with lower arcuate end of surfaces 73 at an arc 79. Extending through the centre of insert 63 is hexagonal aperture 80. The width of insert 63, measured from side 81 to 82 is substantially the same as the distance between sides 71 and 72 of carrier 62 as shown on Figures 22 and 23. Line 83 represents the line of intersection of side 82 and clearance angle 84. Clearance angle 85 forms a similar line to 83 on other side of insert 63. The upper portion of arcuate protrusion 73 extends upwardly from a line drawn horizontally to an extent of 52 degrees as shown on Figure 26. The diameter of protrusion 73 is slightly greater than angular groove 65 shown on Figure 21 and 24, so as to constitute an interference fit. Insert 63 may be formed in one piece or two parts joined together substantially along line 74 in Figure 26. In the case when it is preferred that various cutting, ripping or other inserts of this invention are made of two parts, it is preferred that the major arcuate mating formation portion of an insert is made of high speed steel or other hardenable metals and that cutting or ripping carbide tips be silver soldered onto said major arcuate mating formation. The angle of location — face 78 and stop face 69 is widely variable, including the ^~~ respective faces of all inserts and carriers afore described. In some applications where mounting and mating surfaces are of cylindrical cross section, one member may be provided with one or more grooves and the other with one or more pins to engage with the said grooves in said first member as a means to prevent lateral displacement of cutting insert. The insertion of insert 63 into recess 64, is similar to the afore described procedures. The insert is lowered into recess 64 with face 75 approximately 25 degrees from vertical. Major arcuate mating surfaces 73 and 65 partially engaged and insert is driven to a stop with an appropriate torque key. Forces acting on cutting edge 76 downwardly and axial ly along carrier, will urge the insert into closer engagement with mounting surfaces, resisting abovesaid forces acting in a straight line. Laterally the insert is firmly held by the groove and protrusion formations on mating and mounting surfaces.

If it is elected to have major arcuate mounting and mating formations extending over an angle of about 189 degrees, then a radially intruding stop may be formed at the end of major arcuate recess where the 52 degree arc is shown on Figure 21 and the stop should preferably extend towards the centre of the arc by an amount such that the dimension of the open side of the recess is equal to the chord length of a major arc subtending about 232 degrees. A suitable insert would be complimentary to the afore described recess.

Claims

CLAIMS:

1. A cutting tool insert and carrier assembly comprising: an open sided mounting recess of part circular cross- section formed in said carrier, the cross-section being substantially defined by a major arc of a circle, said arc subtending more than 180 degrees such that the dimension of the open side is less than the diameter of the circle; and a complementary mounting formation on said insert, said mounting formation including a first portion adapted to engage the recess and being of complementary part circular cross-section and an adjacent second portion defining a surface less than a radius distant from the centre of said circle to provide a cross-sectional dimension of said mounting formation less than the dimension of the open side mounting recess to facilitate insertion of said mounting formation into said recess and subsequent engagement of said first portion with the recess surface by rotation.

2. An assembly as defined in claim 1, wherein the major arc of the circle subtends an angle of between 190 degrees and 255 degrees.

3. An assembly as defined in claim 2, wherein the major arc of the circle subtends an angle of between 225 degrees and 232 degrees.

4. An assembly as defined in claim 1, wherein the radius of the part circular first portion of the mounting formation is slightly greater than that of the recess so as to provide an interference fit.

5. An assembly as defined in claim 4, wherein the interference is between l/500th to 1/lOOOth of the diameter of the recess.

6. An assembly as defined in claim 1, wherein the second adjacent portion of the mounting formation forms a chord to the part circular cross-section.

7. An assembly as defined in claim 1, wherein rotation of said mounting formation in said recess is limited by a protruberance mounted on either the carrier or the insert.

8. An assembly as defined in claim 1, wherein the insert is held in position laterally by complementary profiles of the recess and mounting formation.

9. An assembly as definedin claim 8, wherein the complementary profiles are a groove and ridge arrangement.

10. An assembly as defined in claim 9, wherein the ridge is discontinuous and is composed of at least one pin.

11. An assembly as defined in claim 1, wherein the angular extent of the first portion of the mounting formation substantially corresponds with the angular extent of the recess.

12. - An assembly as defined in claim 1, wherein the recess is provided with a resilient pawl, said pawl adapted to be yieldably received in an engagement formation provided on said first portion of said mounting formation.

13. An assembly as defined in claim 12, wherein said pawl is integrally formed from the body of the carrier.

14. An assembly as defined in claim 12, wherein said pawl is inserted into the recess.

15. An assembly as defined in claim 1, wherein the cutting insert is formed of two parts, the mounting formation being one part and made of high speed steel or other hardenable metal, and the other part containing a cutting formation made of tungsten carbide or other hard material, said two parts being joined.

16. An assembly as defined in claim 1, wherein the major arc of the circle subtends about 190 degrees and a radially intruding stop is provided at an end of the arc, said stop extending towards the centre of the arc by an amount such that the dimension of the open side of the recess is equal to the chord length of a major arc subtending about 232 degrees.