Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
  • B24B3/02—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of milling cutters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
  • B24B3/18—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of taps or reamers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
  • B24B3/24—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of drills
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
  • B24C1/02—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for sharpening or cleaning cutting tools, e.g. files
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
  • B24C1/08—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for polishing surfaces, e.g. smoothing a surface by making use of liquid-borne abrasives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C5/00—Devices or accessories for generating abrasive blasts
  • B24C5/02—Blast guns, e.g. for generating high velocity abrasive fluid jets for cutting materials
  • B24C5/04—Nozzles therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
  • B24C1/10—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C3/00—Abrasive blasting machines or devices; Plants
  • B24C3/18—Abrasive blasting machines or devices; Plants essentially provided with means for moving workpieces into different working positions
  • B24C3/20—Abrasive blasting machines or devices; Plants essentially provided with means for moving workpieces into different working positions the work being supported by turntables
  • B24C3/22—Apparatus using nozzles

Definitions

• the current invention relates to a treatment machine.
• it relates to a treatment machine and a method of adjusting the K factor of a cutting edge.
• the reliability and performance of cutting tools has become a more understood and controllable aspect in recent years.
• the microgeometry of cutting edges influences tool life, stability of the cutting process, chip formation, surface quality as well as head and force loads on the tool. It is known that creating a radius on the cutting edge (often referred to as honing the edge) can improve the life of the edge. It has also been shown that the shape of the hone cross section is important.
• This hone cross section shape can be from a constant radius to an increasing or decreasing radius.
• the symmetry of this is currently known as the K factor.
• K is defined as: where Sy is the distance from the apex of the chipping (or rake) surface and clearance (or flank) surface to the end of rounding on the chipping surface and Sa is the distance from the apex to end of rounding on the clearance surface.
• a symmetrical cutting edge microgeometry has a K factor of 1, whilst a larger factor of K > 1 indicates more rounding on the rake face or chipping surface, whilst a K factor of K ⁇ 1 indicates more rounding on the flank face or clearance surface.
• Different sized and radius shapes can be achieved by blasting, brushing, magnet or drag finishing, or by laser. Focussing on blasting, one method of creating an edge radius is by wet blasting. In wet blasting abrasive blast material is combined with a liquid to create a blast slurry, which is then passed through a nozzle of a blast gun or the like at high pressures. The impact of the pressurised slurry or treatment material cleans and ablates the surface to create the desired finish. The amount of material removed is controlled by several variables: the blast pressure of the gas, the angle of the blast stream to the cutting edge, and the size, shape and density of the abrasive particles being used.
• the K factor is more difficult to control and has up to now been attempted by adjusting the angle of the blast stream in relation to the rotational axis of the tool.
• the present invention aims to at least ameliorate the aforementioned disadvantages by providing a more controllable method of adjusting the K factor on cutting edges.
• a treatment machine for adjusting a K factor of a cutting edge of a worktool, said treatment machine comprising: a blast gun for directing a pressurised blast stream slurry of abrasive particles in a blast direction; mounting means for securing the worktool such that a rotational axis of the worktool is radially offset from the blast direction by an offset distance, and wherein control of the offset distance between the blast direction and the rotational axis adjusts the K factor of the cutting edge.
• the present invention provides a more controllable machine for adjusting K factor of cutting edges. As opposed to conventional techniques, which focus on adjusting a blast pitch angle relative to the rotational axis of the worktool, the present invention focusses on the offset distance between the blast stream and the rotational axis worktool.
• the blast direction may comprise a blast axis, which may or may not be perpendicular to the longitudinal axis of the worktool.
• the blast gun is positioned a blast distance from the worktool at a blast angle.
• the blast direction or blast axis is then the direction in which the blast stream slurry is incident against the worktool. It may be considered that the centre of the blast stream incident on the worktool is an origin and the blast gun is positioned a blast distance r at blast angle Q, where r and Q are polar coordinates describing the position of the blast gun relative to the worktool.
• a radial offset distance that aligns the blast direction of the blast stream to be symmetric about the cutting edge provides a K factor of approximately 1. If the offset of the blast stream is offset towards the chipping surface then the K factor can be controlled to be >1. Alternatively, if the offset is away from the chipping surface a K factor can be controlled to be ⁇ 1.
• a blast pattern (being a broad cross-sectional shape of the blast stream) of the blast stream may be non-circular. In an embodiment rectangular blast patterns may be used. This arrangement can aid control of the offset distance between the blast stream compared to when using a circular blast pattern due to the non-linear blast profde presented by such a blast pattern to the worktool.
• the blast pattern may be substantially rectangular such that the long edge of the pattern is directed at the cutting edge.
• the blast pattern may have an aspect ratio of at least 2:1, or may be 5:2, 3:1, 4: 1 or greater.
• the blast pattern comprises a sharp edge. Such sharp edge may be incident against the cutting edge.
• the blast gun of the treatment machine comprises a nozzle for ejecting the pressurised blast stream of abrasive particles in the blast direction.
• the nozzle comprises a slot having a sharp edge, said sharp edge providing a corresponding sharp edge in the blast pattern.
• the long edge of the pattern is the sharp edge.
• the worktool may be a drill bit, end mill, thread tap or slot mill.
• the cutting edge may be the edges of the flute of the drill bit.
• the cutting edge may also refer to the edges of the point angle (end cutting edges).
• the worktool often comprises a round shank, however it can be appreciated that hexagonal, square, trigonal, triangle or other cross-sectional shanks may be used.
• the abrasive particles comprise one or more of particle types such as glass beads, metal shot or aluminium oxide particles. Mixtures or combinations of abrasive particles may be used, with such mixture being tailored to the required finish and materials used. These blends of different abrasive materials can have opposing or complimentary properties - one example blend is glass beads and virgin white aluminium oxide. Virgin aluminium oxide is often used in applications where the worktool may be liable to rusting due to the low iron content of this type of aluminium oxide.
• the pressurised slurry is a wet blast slurry comprising a mixture of the abrasive particles and compressed gas with a liquid to form a pressurised slurry, lubricating the abrasive particles in a buffer of liquid (typically water, although additives may be used to prevent rusting, prevent organic build-up, or the like).
• a buffer of liquid typically water, although additives may be used to prevent rusting, prevent organic build-up, or the like.
• a method of improving a cutting edge of a work tool comprising the steps of: securing the worktool within a blasting chamber, said blasting chamber comprising a wet blast gun for ejecting a stream of abrasive particles suspended in a slurry, out of a nozzle of the blast gun; directing the stream of abrasive particles at a cutting edge of the work tool; and adjusting a radial distance between the nozzle of the blast stream and the rotational axis; wherein the blast nozzle is configured to produce a substantially non-circular cross-section blast stream and wherein the nozzle is aligned substantially perpendicular to the rotational axis.
• Example of K factor control using the present invention will allow the K factor to be adjusted to within an accuracy of 0.02, with a range of K factor values of between 0.4 and 1.9 achievable, with typical control at the accuracy quoted at K factor values of between 0.5 and 1.8. This can be achieved whilst creating a radius of ⁇ 50 microns.
• Figure 1 shows an illustration of how to determine a K factor of a cutting edge
• Figure 2 shows a treatment machine comprising a blast gun according to the present invention, and focussed towards a worktool;
• Figure 3 shows the treatment machine of Figure 2 arranged in a configuration according to the present invention, where the worktool is aligned perpendicular to a blast stream of the blast gun and with a radial offset;
• Figure 4 shows a semi-stylised view of how a blast pattern of the blast stream is directed towards the worktool
• Figure 5a shows a nozzle for the blast gun of Figure 2 according to an embodiment of the present invention
• Figure 5b shows an exploded view of Figure 5a; and Figure 5c shows a cross-sectional view of Figure 5a.
• Figures are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of the Figures have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar feature in modified and different embodiments.
• Figure 1 shows how a K factor of a cutting edge for a worktool (or indeed for any cutting edge) is determined.
• the cutting edge 10 comprises a chipping surface 12 or rake face and a clearance surface 14 or flank face.
• an edge 16 has an edge radius that is an approximation of the radius of a circle 20.
• Sy is the distance from the intersection of the chipping (or rake) surface and clearance (or flank) surface to the end of rounding on the chipping surface, distance 22
• Sa is the distance from the aforesaid intersection to the end of rounding on the clearance surface , distance 24.
• FIG. 2 shows a blasting machine 40 according to a present embodiment of the current invention.
• the blasting machine broadly comprises a blast gun 50 having a first inlet 52 through which a slurry of abrasive particles, such as glass beads, sand, metal shot, aluminium oxides or any suitable blasting media, including mixtures of such abrasive particles, mixed with a fluid, typically water to form a slurry, is combined with compressed gas from a second inlet 54.
• This forms a pressurised blast stream that is directed at a worktool 60.
• the worktool has a rotational axis 62 and is shown as a drill bit, having spiral flutes (which can also be side cutting edges) 64 and end cutting edges 66.
• the blast axis, or blast direction 72 of the blast gun 50 is aligned a blast distance 74 from the worktool at a blast angle 76.
• the intent is to utilise the blast pattern of the blast stream to peen and / or hone the side cutting edges 64 and the end cutting edges 66.
• Prior efforts have focussed on adjusting the blast distance 74 and the blast angle 76 to create the desired K factor for the cutting edges.
• FIG. 3 shows the blasting machine 40 arranged in a configuration according to embodiments of the present invention.
• the blast axis 72 is arranged perpendicular to the rotational axis 62 of the worktool 60.
• the blast axis 72 is offset from the rotational axis 62 by a radial offset distance 80.
• a radial offset of 0 provides a K factor of approximately 1. If the offset of the blast stream is offset towards the chipping surface then the K factor can be controlled to be >1. Alternatively, if the offset is away from the chipping surface a K factor can be controlled to be ⁇ 1..
• a range of K factor values of between 0.4 and 1.9 is possible, with an accuracy of 0.02.. This corresponds to an accuracy of the edge radius of ⁇ 50 microns. Accordingly, by adjusting the offset distance the K factor of the cutting edge to be selected with a high degree of accuracy. It can be appreciated that the blasting machine may still be arranged at a blast angle 76, however in this embodiment the offset distance 80 is varied to adjust the K factor accordingly.
• Figure 4 shows the worktool 60 when subjected to a directed blast stream from the blasting machine of figure 3.
• the effect of blast stream pattern or shape can be seen.
• the blast media is difficult to align at the cutting edges of the flutes 64 or the end cutting edge 66 - this leads to either wasted blast media, or more likely to an inaccurate finish, making control of the K factor of cutting edges difficult.
• an attempt to adjust the K factor of middle flutes 64 is likely to also affect already treated lower flutes leading to inconsistent results.
• embodiments of the present invention utilise a non-circular blast pattern 90, such as a rectangular blast pattern.
• a non-circular blast pattern 90 such as a rectangular blast pattern.
• the use of such a blast pattern, particularly with the above described configuration allows for a greater control and adjustment of the K factor of the cutting edges.
• Typical non-circular blast patterns are rectangular, although square or elliptical patterns may also be used depending on the shape of the cutting edge to be honed.
• Typical aspect ratios for such non-circular blast patterns are 2: 1, although 5:3, 3: 1, 4: 1 may also be used.
• the use of a thin blast pattern with this blasting machine configuration allows the K factor to be adjusted in a finer manner than previously.
• FIG. 5a to 5c An exemplary embodiment of a nozzle 100 for producing a non-circular blast pattern 90 is shown in Figures 5a to 5c.
• Such nozzle 100 has a substantially rectangular or square shaped slot or end nozzle 110 from which the slurry of abrasive particles may be ejected.
• Said nozzle 100 comprises a base portion 120 having a sloped base surface 122. It can be appreciated that the end nozzle 110 has a sharp edge.
• the sloped base portion extends into a flat base portion 124.
• Said flat base portion 124 extends into the nozzle 100.
• An air guide 130 is connected above the base of the nozzle past the flat base portion 124.
• the air guide 130 is a broadly flat surface having a chamfered end surface 131 that meets the end of the slot 110 as the slot opens out into a larger slurry chamber .
• the air guide 130 is secured by screws 140.
• the air guide 130 is secured above the base of the nozzle base surface 124 to allow a channel 139 through which air can pass via an air inlet 138.
• a slurry guide 132 is provided in addition to the air guide 130.
• the slurry guide 132 is co-located opposite the air guide but is located opposite the sloped base surface 122 and the flat base portion 124 within the slot 110.
• a chamfered edge 133 is also provided.
• the slurry guide is secured to a top plate 134 of the nozzle using screws 142.
• the top plate caps the nozzle, leaving an exposed rectangular opening at the slot 110.
• the top plate comprises a slurry entry point or hole 136 through which slurry may be injected.
• the top plate secures the air guide 130, slurry guide 132 and the top plate 130 to the base portion 120 using screws 148, washers 146 and nuts 144.
• air is injected into the nozzle at inlet 138.
• the air passes along channel 139 before exiting opposite the air guide 132.
• a slurry of abrasive particles enter via slurry inlet 136.
• the slurry is guided by the slurry guide 130, down chamfer 131 and against chamfer 133 of the air guide. At this point it mixes with the pressurised air from the air inlet 136.
• the pressurised air/slurry mixture is then guided via the air guide towards the nozzle end slot 120 where the pressurised blast stream exits.
• the sloped base portion 122 of the base portion 120 and the shape of the slot create a substantially rectangular shaped blast stream. It can be appreciated that rectangular (or square, or other non-circular) shaped blast stream formed by the correspondingly shaped end nozzle slot 112 provide a sharp edge to the blast stream, rather than a traditional funnel shaped blast stream from a conventional circular nozzle.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Applications Claiming Priority (2)

Publications (3)

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ID=69527879

Family Applications (1)

Country Status (6)

Families Citing this family (2)

Family Cites Families (19)

• 2020
  • 2020-01-07 GB GB2000195.4A patent/GB2590936B/en active Active
• 2021
  • 2021-01-11 US US17/791,491 patent/US20230037473A1/en active Pending
  • 2021-01-11 WO PCT/EP2021/050414 patent/WO2021140255A1/en not_active Ceased
  • 2021-01-11 EP EP21700533.9A patent/EP4087705B1/de active Active
  • 2021-01-11 KR KR1020227026874A patent/KR20220126291A/ko not_active Withdrawn
  • 2021-01-11 JP JP2022542042A patent/JP7731142B2/ja active Active

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