US20060151904A1 - Molding apparatus and method for making a cutting tool - Google Patents
Molding apparatus and method for making a cutting tool Download PDFInfo
- Publication number
- US20060151904A1 US20060151904A1 US11/328,797 US32879706A US2006151904A1 US 20060151904 A1 US20060151904 A1 US 20060151904A1 US 32879706 A US32879706 A US 32879706A US 2006151904 A1 US2006151904 A1 US 2006151904A1
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- Prior art keywords
- bag
- sleeve
- end cap
- mold
- exterior
- 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.)
- Abandoned
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/02—Compacting only
- B22F3/04—Compacting only by applying fluid pressure, e.g. by cold isostatic pressing [CIP]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
- B23P15/28—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools
- B23P15/32—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools twist-drills
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
- B22F2005/001—Cutting tools, earth boring or grinding tool other than table ware
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/32—Component parts, details or accessories; Auxiliary operations
- B29C2043/3205—Particular pressure exerting means for making definite articles
- B29C2043/3238—Particular pressure exerting means for making definite articles pressurized liquid acting directly or indirectly on the material to be formed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/32—Component parts, details or accessories; Auxiliary operations
- B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
- B29C43/3642—Bags, bleeder sheets or cauls for isostatic pressing
- B29C2043/3649—Inflatable bladders using gas or fluid and related details
Definitions
- the present invention relates to cutting tools, and more particularly, to a mold and method for making a sintered carbide cutting tool.
- Machine cutting tools can be produced from a variety of materials, including but not limited to carbon steel, high-speed steel, cobalt high-speed steel, tungsten carbide, and the like. Cutting tools made from cobalt and/or carbide can withstand higher operating temperatures and can thus be run at higher cutting speeds and feeds than tools made from carbon steel or high-speed steel. Cutting tools containing cobalt and/or carbide, however, may be more time consuming and costly to produce than tools made from carbon steel or high-speed steel due to the increased hardness of the materials.
- the process of producing a twist drill from carbon steel may involve rough milling a cylindrically-shaped blank to produce drill flutes in a straight line along the length of the blank.
- the milled blank can then be heated and twisted to form the flutes into a desired helix.
- the twist drill can then be semi-finished milled and ground to size.
- the manufacturing process generally becomes more complex and time consuming when producing cutting tools made from cobalt and/or carbide.
- manufacturing twist drills from carbide may require more extensive and complex machining operations to produce than tools made from carbon steel of high-speed steel.
- a preferred embodiment of a molding apparatus for making a cutting tool includes a cylindrically shaped elastic bag having an internal cavity for receiving a granulated material, such as a mixture of cobalt and carbide.
- the profile of the interior cavity substantially corresponds to the shape of the cutting tool being produced.
- the ends of the bag are open to provide access to the interior cavity of the bag.
- a further aspect of the invention includes a substantially rigid tubular-shaped pressure sleeve that encloses an outer circumference of the elastic bag.
- Yet another aspect of the invention includes a pair of end caps that operate to seal the open ends of the elastic bag and are engageable with the ends of the pressure sleeve.
- the granulated material can be formed into a solid coherent structure by placing the assembled mold containing the granulated material into a hydrostatic press for applying a substantially uniform compressive load to the outer periphery of the elastic bag. After forming, the cutting tool blank can be removed from the mold and may be subjected to further processing.
- FIG. 1 is an exploded perspective view of a preferred embodiment mold of the present invention for manufacturing a cutting tool
- FIG. 2 is a cross-sectional view of a flexible bag employed in the preferred embodiment mold, taken along line 2 - 2 of FIG. 1 ;
- FIG. 3 is longitudinal cross-sectional view of the flexible bag employed in the preferred embodiment mold
- FIG. 4A is a side elevational view of an end cap incorporating a straight core pin employed in the preferred embodiment mold
- FIG. 4B is a top elevational view of the end cap incorporating a straight core pin
- FIG. 5A is a side elevational view of a second end cap employed in the preferred embodiment mold:
- FIG. 5B is a top elevational view of the end cap shown in FIG. 5A ;
- FIG. 6A is a side elevational view of an exemplary cutting tool that can be formed using the mold and method of the present invention.
- FIG. 6B is a side elevational view of the exemplary cutting tool shown in FIG. 4A , viewed perpendicular to the cutting flutes;
- FIG. 7 is a perspective view of the flexible bag employed in the preferred embodiment mold shown with an end cap attached to one end of the bag;
- FIG. 8 is a side elevational view of certain components of the preferred embodiment mold shown being filled with a carbide mixture while resting on a mechanical vibrating plate, with certain components shown in cross-section;
- FIG. 9 is side perspective view of a pressure sleeve employed with the preferred embodiment mold.
- FIG. 10 is a side perspective view of the mold with certain components shown disassembled from the mold;
- FIG. 11 is a side elevational view of a exemplary installation tool
- FIG. 12 is a side elevational view of the flexible bag showing the exemplary cutting tool of FIGS. 6A and 6B being separated from the bag;
- FIG. 13 is a diagrammatic representation of a method for forming a cutting tool using the preferred embodiment mold.
- FIG. 14 is a side elevational view of an end cap incorporating a helical core pin employed in the preferred embodiment mold.
- the cutting tool may have one or more internal passages. Mold 20 can be used to form a variety of differently configured cutting tools, such as end mills, reamers, twist drills, straight flute drills, and the like.
- the cutting tools may be formed from materials known to be used in the production of cutting tools, such as powdered carbide mixtures.
- One such carbide mixture consists of finely ground carbide and cobalt combined with one or more binder materials, such as wax.
- the binder material operates to hold the particles of material together when forming the carbide mixture into a desired shape.
- the carbide mixture may include, for example, 90% carbide, 9% cobalt, and 1% other trace elements by volume.
- a wax binder may also be added to the mixture in an approximate ratio of one (1) part wax binder to forty-nine (49) parts carbide mixture.
- Straight flute drill 22 that can be produced using mold 20 and the method of the present invention.
- Straight flute drill 22 is merely one example of the various types of cutting tools that can be produced using the mold and method of the present invention.
- Straight flute drill 22 is shown to have a generally cylindrical shape.
- a pair of diameterally opposed recessed channels 24 extend lengthwise over a portion of straight flute drill 22 .
- Channels 24 define edges of a pair of flutes 26 forming a cutting surface of straight flute drill 22 .
- Straight flute drill 22 includes an elongated internal passage 28 oriented along a central longitudinal axis of straight flute drill 22 for supplying a fluid to an end 36 of straight flute drill 22 .
- Cooling passage 28 includes an inlet port 30 located in an end 32 of straight flute drill 22 opposite flutes 26 .
- An end 34 of passage 28 opposite inlet 30 terminates short of end 36 of straight flute drill 22 so as to not penetrate end 36 .
- a pair of opposing discharge passages 38 extend from passage 28 and have an exit port 40 located within recessed channel 24 .
- passage 28 is shown to have a substantially linear tube-like configuration, it shall be appreciated that differently configured cooling passages may also be produced using mold 20 , including but not limited to, helical shaped passages and passages having multiple inlet and exit ports.
- mold 20 includes a generally cylindrical-shaped bag 42 having a first end 47 and a second end 49 .
- Bag 42 has a hollow interior cavity 44 .
- bag 42 is shown to have an interior profile corresponding to straight flute drill 22 . It shall be appreciated, however, that bag 42 may also include a different interior profile depending on the particular cutting tool being produced. It shall also be understood the dimensions and/or profile of the cutting tool formed using bag 42 may differ from those of interior cavity 44 . The dimension of interior cavity 44 may be larger than the resulting cutting tool due to compacting of the carbide material used to produce the cutting tool during the forming process.
- Bag 42 preferably has a generally cylindrical shape with a circular cross-section. Other cross-sectional shapes, however, may also be used with satisfactory results, such as octagonal, hexagonal, and the like.
- Inner cavity 44 includes a pair of elongated ribs 46 protruding inward toward a center of cavity 44 . Ribs 46 are positioned opposite one another at 180 degree intervals and correspond to recessed channels 24 of straight flute drill 24 .
- Bag 42 is preferably made from a resilient elastic material having a Durometer hardness of approximately 35-40, such as urethane, silicone, or another material having similar physical characteristics. It is preferable the bag material be capable of withstanding multiple compression cycles involving compressive loads in excess of 30,000 psi without incurring any appreciable degradation of the physical properties of the material. Its also preferable the bag material not incur a permanent set as a result of the compressive loads.
- mold 20 includes a first end cap 48 for sealing end 47 of bag 42 .
- End cap 48 has a generally circular disk-shaped portion 50 having an end surface 52 engagable with end 47 of bag 42 when end cap 48 is attached to the bag.
- An L-shaped notch 54 extends around an entire circumference 56 of disk portion 50 .
- a first surface 58 of notch 52 is oriented substantially parallel to a center axis of disk portion 50 and intersects end surface 52 of disk portion 50 .
- a second surface 60 of notch 52 is oriented substantially perpendicular to the center axis of disk portion 50 and intersects outer circumference 56 of disk portion 50 .
- Surface 58 preferably has a diameter larger than the diameter of bag 42 .
- disk portion 50 may also be configured to have other shapes, such as hexagonal, octagonal, and the like.
- shape such as hexagonal, octagonal, and the like.
- bag 42 has a hexagonal cross-sectional shape
- notch surface 58 also have a hexagonal shape
- outer circumference 56 also have a hexagonal shape.
- a cylindrically-shaped boss 62 Extending from end surface 52 of disk portion 50 is a cylindrically-shaped boss 62 having an outer circumference surface 64 .
- a center axis of boss 62 substantially coincides with the center axis of disk portion 50 .
- Boss 62 may be integrally formed with disk portion 50 , or may be fixedly attached using any suitable method, such as brazing, welding, gluing, and the like.
- boss 62 With end cap 48 attached to bag 42 , boss 62 extends into cavity 44 , wherein circumference 64 engages the interior periphery of cavity 44 .
- the outer diameter of circumference 64 is preferably larger than the diameter of cavity 44 adjacent end 47 of bag 42 to produce an interference fit between bag 42 and boss 64 when attaching end cap 48 to bag 42 .
- core pin 68 Attached to an end surface 66 of boss 62 opposite disk portion 50 is a core pin 68 for forming passage 28 of straight flute drill 22 .
- core pin 68 is: shown to have a rod-like shape, it shall be appreciated that core pin 68 may also be configured to produce a passage having a different shape, such as helical core pin 69 shown in FIG. 14 .
- Core pin 68 may be permanently attached to boss 62 using any suitable means, such as welding, brazing, adhesives, and the like. Alternatively, core pin 68 may be removably attached to boss 62 , such as by threading, to enable differently configured core pins to be readily interchanged.
- First transition member 70 provides an elastic transition between rigid boss 70 and interior cavity 44 of bag 42 to minimize possible flaring of the end of the cutting tool formed using mold 20 .
- a center axis of first transition member 70 substantially coincides with the center axis of boss 62 and disk portion 50 .
- First transition member 70 includes a bore 74 oriented along the longitudinal center axis of first transition member 70 . Bore 74 is engageable with core pin 68 .
- first transition member 70 extends into cavity 44 enabling circumference 72 of the first transition member to engage the interior periphery of cavity 44 .
- the outer diameter of circumference 72 preferably is larger than the diameter of cavity 44 adjacent end 47 of bag 42 so as to produce an interference fit between bag 42 and first transition member 70 when attaching end cap 48 to bag 42 .
- First transition member 70 is preferably made of a resilient material, such as rubber, but may also be made of another material having similar properties.
- End cap 48 can be attached to bag 42 by guiding core pin 68 , first transition member 70 , and boss 62 into cavity 44 of bag 42 until end surface 52 of disk portion 50 contacts end surface 47 of bag 42 .
- Bag 42 may be secured to end cap 48 using a strap 112 a. Strap 112 a is preferably placed around bag 42 and in alignment with boss 62 . Strap 112 a can then be tightened to secure bag 42 to end cap 48 .
- Mold 20 further includes a second end cap 76 for sealing end 49 of bag 42 to prevent fluid from entering cavity 44 from the exterior of bag 42 .
- End cap 76 has a generally circular disk-shaped portion 78 having an end surface 80 that is engageable with end 49 of bag 42 when end cap 76 is attached to bag 42 .
- An L-shaped notch 82 extends around an entire circumference 84 of disk portion 78 .
- a first surface 86 of notch 82 is oriented substantially parallel to a center axis of disk portion 78 and intersects end surface 80 of disk portion 78 .
- a second surface 88 of notch 82 is oriented substantially perpendicular to the center axis of disk portion 78 and intersects outer circumference 84 of disk portion 78 .
- Surface 86 preferably has a diameter larger than the outer diameter of bag 42 .
- disk portion 78 may also be provided with a different shape, such as hexagonal, octagonal, and the like, so as to substantially mirror the shape of the outer periphery of bag 42 .
- a different shape such as hexagonal, octagonal, and the like.
- notch surface 86 likewise have a hexagonal shape.
- outer circumference 84 of disk portion 78 also have a hexagonal shape.
- a cylindrically-shaped boss 90 Extending from end surface 80 of disk portion 78 is a cylindrically-shaped boss 90 having an outer circumference surface 92 .
- a center axis of boss 90 substantially coincides with the center axis of disk portion 78 .
- Boss 90 may be integrally formed with disk portion 78 , or may be fixedly attached using any suitable method, such as brazing, welding, gluing, and the like. With end cap 76 attached to bag 42 , boss 90 extends into cavity 44 so that circumference 92 engages the interior periphery of cavity 44 of bag 42 .
- the outer diameter of circumference 92 of boss 90 is preferably larger than the interior diameter of cavity 44 of bag 42 to produce an interference fit between bag 42 and boss 90 when engaging end cap 76 with bag 42 .
- Mold 20 further includes a washer-shaped seal 94 .
- Seal 94 is positionable between end cap 76 and bag 42 when end cap 76 is attached to bag 42 .
- a first surface 96 of seal 94 is engagable with surface 80 of end cap 76
- an opposite surface 98 of seal 94 is engageable with end surface 49 of bag 42 .
- Seal 94 includes a circular-shaped aperture 100 that is engagable with circumference 92 of boss 90 .
- Aperture 100 preferably has a diameter smaller than the diameter of circumference 92 to produce an interference fit between seal 94 and boss 90 when the two components are assemble together.
- Seal 94 is preferably made from an resilient elastic material, such as rubber, or another material having similar physical properties.
- a second transition member 102 having an outer circumference 104 is insertable within interior cavity 44 of bag 42 .
- Second transition member 102 can be engaged with inner cavity 44 of bag 42 and operates to accomplish the same general function as first transition member 70 by providing an elastic transition between rigid boss 90 and interior cavity 44 of bag 42 to minimize possible flaring of the end of the cutting tool formed using mold 20 .
- a threaded bore 106 is provided in one end of second transition member 102 for engaging a correspondingly threaded insertion tool 108 (see FIG. 11 ) that can be used for inserting second transition member 102 into cavity 44 .
- outer circumference 104 of second transition member 102 engages the inner periphery of cavity 44 .
- the outer diameter of circumference 104 preferably is larger than the inner diameter of cavity 44 adjacent end 49 of bag 42 to produce an interference fit between bag 42 and second transition member 102 .
- Second transition member 102 is preferably made of a resilient material, such as rubber, or alternatively, another material having similar properties.
- Second transition member 102 can be installed in cavity 44 of bag 42 by engaging a threaded end 110 of installation tool 108 with threaded bore 106 of second transition member 102 . With second transition member 102 attached to installation tool 108 , second transition member 106 can be inserted into cavity 44 of bag 42 , after which installation tool 108 can be detached from second transition member 102 .
- Seal 94 can be positioned adjacent end surface 49 of bag 42 with aperture 100 substantially aligned with the opening to cavity 44 in end 49 of bag 42 .
- End cap 76 can be attached to bag 42 by guiding boss 90 into cavity 44 of bag 42 until end surface 80 of disk portion 78 contacts end surface 49 of bag 42 .
- Bag 42 may be secured to end cap 76 using a strap 112 b. Strap 112 b is preferably positioned around bag 42 and in alignment with boss 90 . Strap 112 b can then be tightened to secure bag 42 to end cap 48 .
- Mold 20 may also include a fill sleeve 114 and a pressure sleeve 118 .
- the two sleeves are not used simultaneously, with each serving a separate function.
- fill sleeve 114 can be positioned over bag 42 prior to filling bag 42 with a powdered carbide mixture 115 , or a like material having properties suitable for producing cutting tools.
- Filling bag 42 with carbide mixture 115 may cause bag 42 to expand due to the bag's elastic nature.
- Fill sleeve 114 operates to limit the amount of expansion that may occur during the filling process.
- Fill sleeve 114 has a generally hollow tubular shape with an inner diameter sufficiently large to allow fill sleeve 114 to be slid over bag 42 .
- Fill sleeve 114 and bag 42 preferably are substantially the same length.
- An end 116 of fill sleeve 114 is engageable with surface 52 of end cap 48 when fill sleeve 114 is placed over bag 42 .
- Bag 42 can be filled with a predetermined quantity of powdered carbide mixture 115 .
- Fill sleeve 114 can be removed from bag 42 once cavity 44 is suitably filled with carbide mixture 115 .
- mold 42 may also include a cylindrically-shaped pressure sleeve 118 .
- Pressure sleeve 118 can be positioned over bag 42 so as to enclose at least a portion of the exterior periphery 120 of bag 42 .
- Pressure sleeve 118 provides support for bag 42 and helps maintain proper alignment of the bag during the pressure forming processes.
- a first end 122 of pressure sleeve 118 is engageable with notch 54 formed in end cap 48 and a second end 124 is engageable with notch 82 formed in end cap 76 .
- the diameter of an inner circumference 121 of first end 122 of pressure sleeve 118 is larger than the diameter of surface 58 of notch 54 to enable pressure sleeve 118 to slide over surface 58 and engage surface 60 of notch 54 .
- the diameter of inner circumference 121 of end 124 of pressure sleeve 118 is larger than the diameter of surface 86 of notch 82 to enable pressure sleeve 118 to slide over surface 86 and engage surface 88 of notch 82 .
- the inside diameter of circumference 121 of pressure sleeve 118 is also preferably larger than the diameter of the exterior periphery 120 of bag 24 to produce a circumferential gap 126 between inner circumference 121 of pressure sleeve 118 and exterior periphery 120 of bag 42 .
- Each end 122 and 124 of pressure sleeve 118 includes a notched region 128 and 130 , respectively. Notched regions 128 and 130 provide access to straps 112 a and 112 b, and allow fluid to enter gap 126 formed between pressure sleeve 118 and bag 42 during the forming process.
- One or more apertures 132 extend through a wall 134 of pressure sleeve 118 for fluidly connecting the exterior region of pressure sleeve 118 with the interior region of the pressure sleeve.
- a cutting tool such as straight flute drill 22
- Strap 112 a is not used to attach bag 42 to end cap 48 at this time.
- Fill sleeve 114 can be slid over bag 42 and end 116 of fill sleeve 114 can be engaged with end surface 52 of end cap 48 .
- Bag 42 can then be filled with a predetermined quantity of powdered carbide mixture 115 .
- end cap 48 , fill sleeve 114 , and bag 42 can be placed on a mechanical vibrating plate 134 , or another similar device.
- Vibrating plate 134 includes a plate 135 that can made to vibrate at a predetermined frequency. Vibrating the end cap/fill sleeve/bag assembly ( 48 , 114 , 42 ) helps to eliminate voids that could form in carbide mixture 115 and prevent cavity 44 from being filled with the desired quantity of carbide mixture 115 . Sleeve 114 can be removed from bag 42 after the bag is filled with the desired quantity of carbide mixture 115 .
- end 47 of bag 42 may be secured to end cap 48 using strap 112 a.
- Pressure sleeve 118 is then slid over bag 42 and end 122 of pressure sleeve 118 is engaged with notch 54 of end cap 48 .
- Second strap 112 b is initially loosely installed around end 49 of bag 42 .
- End cap 48 may be secured to pressure sleeve 118 by releasably engaging a pair of clips 131 with a pair of pockets 133 formed in an end surface 135 of end cap 48 .
- Second transition member 102 can be attached to installation tool 108 and inserted into cavity 44 of bag 42 to the point where end surface 136 of second transition member 102 contacts carbide mixture 115 .
- End 49 of bag 42 is sealed to prevent fluid from entering cavity 44 from the exterior region of bag 42 by positioning seal 94 adjacent end 49 of bag 42 .
- End cap 76 is then attached to end 49 of bag 42 by guiding boss 92 of end cap 76 into cavity 44 of bag 42 until notch 82 of end cap 76 engages end 124 of pressure sleeve 118 .
- End cap 76 can be secured to end 49 of bag 42 by tightening second strap 112 b around bag 42 .
- End cap 76 may also be secured to pressure sleeve 118 by releasably engaging a pair of clips 137 with a pair of pockets 139 formed in an end surface 139 of end cap 76 .
- carbide mixture 115 can be pressed into a solid form using a known isostatic press 140 , or a similar device. Mold 20 containing carbide mixture 115 is placed in isostatic press 140 , whereupon the isostatic press is activated (see step 142 ).
- Isostatic press 140 utilizes a high pressure liquid, preferably operating at a pressure in excess of 20,000 psi, to apply a generally uniform compressive load to at least a portion of the exterior of mold 20 .
- the high pressure fluid flows through orifice 132 and notched regions 128 and 130 of pressure sleeve 118 into gap 126 formed between bag 42 and pressure sleeve 116 .
- the high pressure fluid present in gap 126 exerts a substantially uniform pressure along at least a portion of exterior surface 120 of bag 42 .
- the high pressure fluid causes bag 42 to compress radially, compacting carbide mixture 115 into a cohesive structure.
- Rigid pressure sleeve 118 prevents carbide mixture 115 from being compressed axially.
- the high pressure fluid surrounding mold 20 is discharged and mold 20 is removed from isostatic press 140 .
- Bag 42 containing the compressed carbide mixture can be separated from mold 20 by first disengaging clips 131 from end cap 48 and clips 137 from end cap 76 . Straps 112 a and 112 b can then be released to allow end caps 76 and 48 to be detached from bag 42 . Bag 42 can then be withdraw from pressure sleeve 118 . Transition member 102 can be removed from cavity 44 of bag 42 using installation tool 108 . Referring to FIG. 12 and step 144 of FIG. 13 , a “green state” straight flute drill 22 a, being of substantially the same configuration as straight flute drill 22 (see FIGS. 6A and 6B ) can be extracted from bag 42 by applying a force 141 to the fluted end 32 a of straight flute drill 22 a to force straight flute drill 22 a out through the access opening to cavity 44 located in end 47 of bag 42 .
- cooling passages 38 are drilled in straight flute drill 22 a using a drill press 148 , or another suitable tool.
- straight flute drill 22 a may be placed in a suitably configured fixture 149 .
- the cooling passages be drilled while straight flute drill 22 a is in a “green state” prior to undergoing heat treatment.
- the cooling passages may be formed at any other desired stage of the forming process.
- straight flute drill 22 a can be placed in a pre-sintering furnace 150 preheated to a predetermined temperature, for example 600° F. Heating straight flute drill 22 a causes the wax binder to be removed from straight flute drill 22 a. Straight flute drill 22 a is maintained at the elevated temperature for a predetermined period of time after which it is removed from pre-sintering furnace 150 and allowed to cool to approximately room temperature.
- the heat treated straight flute drill is identified by reference number 22 b.
- an outer circumference 152 of straight flute drill 22 b may be ground to achieve a desired surface finish and diameter using a conventional centerless grinder 154 , or another suitable apparatus (see step 151 ).
- Straight flute drill 22 b can then be heated in a high temperature sintering furnace 156 preheated to a predetermined temperature in step 155 .
- Sintering furnace 156 is preferably capable of performing a known heating cycle so as to cause the individual particles in carbide mixture 115 to bind together and form a unitary solid straight flute drill 22 c having certain desirable physical properties that enable straight flute drill 22 c to function as a cutting tool.
- straight flute drill 22 c may undergo further processing in step 158 after being removed from sintering furnace 156 , such as grinding cutting flutes on an end 36 c of straight flute drill 22 c using conventional grinding methods in step.
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Abstract
A molding apparatus for making a cutting tool includes a cylindrically shaped elastic bag having an internal cavity for receiving a granulated material, such as a mixture of cobalt and carbide. The profile of the interior cavity substantially corresponds to the shape of the cutting tool being produced. The ends of the bag are open to provide access to the interior cavity of the bag. A substantially rigid tubular-shaped pressure sleeve encloses an outer circumference of the elastic bag. A pair of end caps operate to seal the open ends of the elastic bag and are engageable with the ends of the pressure sleeve. The granulated material can be formed into a solid coherent structure by placing the assembled mold containing the granulated material into a hydrostatic press for applying a substantially uniform compressive load to the outer periphery of the elastic bag.
Description
- This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 60/642,635 filed Jan. 10, 2005, which is hereby incorporated in its entirety.
- The present invention relates to cutting tools, and more particularly, to a mold and method for making a sintered carbide cutting tool.
- Machine cutting tools can be produced from a variety of materials, including but not limited to carbon steel, high-speed steel, cobalt high-speed steel, tungsten carbide, and the like. Cutting tools made from cobalt and/or carbide can withstand higher operating temperatures and can thus be run at higher cutting speeds and feeds than tools made from carbon steel or high-speed steel. Cutting tools containing cobalt and/or carbide, however, may be more time consuming and costly to produce than tools made from carbon steel or high-speed steel due to the increased hardness of the materials.
- There exists a variety of known manufacturing methods for producing cutting tools. For example, the process of producing a twist drill from carbon steel may involve rough milling a cylindrically-shaped blank to produce drill flutes in a straight line along the length of the blank. The milled blank can then be heated and twisted to form the flutes into a desired helix. The twist drill can then be semi-finished milled and ground to size. The manufacturing process generally becomes more complex and time consuming when producing cutting tools made from cobalt and/or carbide. For example, manufacturing twist drills from carbide may require more extensive and complex machining operations to produce than tools made from carbon steel of high-speed steel. The time and cost of producing cutting tools from cobalt and/or carbide could be reduced by producing a cutting tool blank that more nearly approximates the finished shape of the cutting tool. Accordingly, there is a need to develop an apparatus and method for manufacturing a cutting tool that more closely approximates the finished shape of the cutting tool being produced.
- In accordance with the present invention, a preferred embodiment of a molding apparatus for making a cutting tool includes a cylindrically shaped elastic bag having an internal cavity for receiving a granulated material, such as a mixture of cobalt and carbide. The profile of the interior cavity substantially corresponds to the shape of the cutting tool being produced. The ends of the bag are open to provide access to the interior cavity of the bag. A further aspect of the invention includes a substantially rigid tubular-shaped pressure sleeve that encloses an outer circumference of the elastic bag. Yet another aspect of the invention includes a pair of end caps that operate to seal the open ends of the elastic bag and are engageable with the ends of the pressure sleeve. The granulated material can be formed into a solid coherent structure by placing the assembled mold containing the granulated material into a hydrostatic press for applying a substantially uniform compressive load to the outer periphery of the elastic bag. After forming, the cutting tool blank can be removed from the mold and may be subjected to further processing.
- The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
-
FIG. 1 is an exploded perspective view of a preferred embodiment mold of the present invention for manufacturing a cutting tool; -
FIG. 2 is a cross-sectional view of a flexible bag employed in the preferred embodiment mold, taken along line 2-2 ofFIG. 1 ; -
FIG. 3 is longitudinal cross-sectional view of the flexible bag employed in the preferred embodiment mold; -
FIG. 4A is a side elevational view of an end cap incorporating a straight core pin employed in the preferred embodiment mold; -
FIG. 4B is a top elevational view of the end cap incorporating a straight core pin; -
FIG. 5A is a side elevational view of a second end cap employed in the preferred embodiment mold: -
FIG. 5B is a top elevational view of the end cap shown inFIG. 5A ; -
FIG. 6A is a side elevational view of an exemplary cutting tool that can be formed using the mold and method of the present invention; -
FIG. 6B is a side elevational view of the exemplary cutting tool shown inFIG. 4A , viewed perpendicular to the cutting flutes; -
FIG. 7 is a perspective view of the flexible bag employed in the preferred embodiment mold shown with an end cap attached to one end of the bag; -
FIG. 8 is a side elevational view of certain components of the preferred embodiment mold shown being filled with a carbide mixture while resting on a mechanical vibrating plate, with certain components shown in cross-section; -
FIG. 9 is side perspective view of a pressure sleeve employed with the preferred embodiment mold; -
FIG. 10 is a side perspective view of the mold with certain components shown disassembled from the mold; -
FIG. 11 is a side elevational view of a exemplary installation tool; -
FIG. 12 is a side elevational view of the flexible bag showing the exemplary cutting tool ofFIGS. 6A and 6B being separated from the bag; -
FIG. 13 is a diagrammatic representation of a method for forming a cutting tool using the preferred embodiment mold; and -
FIG. 14 is a side elevational view of an end cap incorporating a helical core pin employed in the preferred embodiment mold. - The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
- Referring to
FIG. 1 , there is shown amold 20 for producing a cutting tool in accordance with the present invention. The cutting tool may have one or more internal passages. Mold 20 can be used to form a variety of differently configured cutting tools, such as end mills, reamers, twist drills, straight flute drills, and the like. The cutting tools may be formed from materials known to be used in the production of cutting tools, such as powdered carbide mixtures. One such carbide mixture consists of finely ground carbide and cobalt combined with one or more binder materials, such as wax. The binder material operates to hold the particles of material together when forming the carbide mixture into a desired shape. The carbide mixture may include, for example, 90% carbide, 9% cobalt, and 1% other trace elements by volume. A wax binder may also be added to the mixture in an approximate ratio of one (1) part wax binder to forty-nine (49) parts carbide mixture. - Referring to
FIGS. 6A and 6B , there is shown an exemplarystraight flute drill 22 that can be produced usingmold 20 and the method of the present invention.Straight flute drill 22 is merely one example of the various types of cutting tools that can be produced using the mold and method of the present invention. -
Straight flute drill 22 is shown to have a generally cylindrical shape. A pair of diameterally opposed recessedchannels 24 extend lengthwise over a portion ofstraight flute drill 22.Channels 24 define edges of a pair offlutes 26 forming a cutting surface ofstraight flute drill 22. -
Straight flute drill 22 includes an elongatedinternal passage 28 oriented along a central longitudinal axis ofstraight flute drill 22 for supplying a fluid to anend 36 ofstraight flute drill 22. Coolingpassage 28 includes aninlet port 30 located in anend 32 ofstraight flute drill 22opposite flutes 26. Anend 34 ofpassage 28opposite inlet 30 terminates short ofend 36 ofstraight flute drill 22 so as to not penetrateend 36. A pair of opposingdischarge passages 38 extend frompassage 28 and have anexit port 40 located within recessedchannel 24. Althoughpassage 28 is shown to have a substantially linear tube-like configuration, it shall be appreciated that differently configured cooling passages may also be produced usingmold 20, including but not limited to, helical shaped passages and passages having multiple inlet and exit ports. - Referring to
FIGS. 1-3 ,mold 20 includes a generally cylindrical-shapedbag 42 having afirst end 47 and asecond end 49.Bag 42 has a hollowinterior cavity 44. For purposes of illustration,bag 42 is shown to have an interior profile corresponding tostraight flute drill 22. It shall be appreciated, however, thatbag 42 may also include a different interior profile depending on the particular cutting tool being produced. It shall also be understood the dimensions and/or profile of the cutting tool formed usingbag 42 may differ from those ofinterior cavity 44. The dimension ofinterior cavity 44 may be larger than the resulting cutting tool due to compacting of the carbide material used to produce the cutting tool during the forming process. -
Bag 42 preferably has a generally cylindrical shape with a circular cross-section. Other cross-sectional shapes, however, may also be used with satisfactory results, such as octagonal, hexagonal, and the like.Inner cavity 44 includes a pair ofelongated ribs 46 protruding inward toward a center ofcavity 44.Ribs 46 are positioned opposite one another at 180 degree intervals and correspond to recessedchannels 24 ofstraight flute drill 24. -
Bag 42 is preferably made from a resilient elastic material having a Durometer hardness of approximately 35-40, such as urethane, silicone, or another material having similar physical characteristics. It is preferable the bag material be capable of withstanding multiple compression cycles involving compressive loads in excess of 30,000 psi without incurring any appreciable degradation of the physical properties of the material. Its also preferable the bag material not incur a permanent set as a result of the compressive loads. - Referring also to
FIGS. 4A-5B ,mold 20 includes afirst end cap 48 for sealingend 47 ofbag 42.End cap 48 has a generally circular disk-shapedportion 50 having anend surface 52 engagable withend 47 ofbag 42 whenend cap 48 is attached to the bag. An L-shapednotch 54 extends around anentire circumference 56 ofdisk portion 50. Afirst surface 58 ofnotch 52 is oriented substantially parallel to a center axis ofdisk portion 50 and intersectsend surface 52 ofdisk portion 50. Asecond surface 60 ofnotch 52 is oriented substantially perpendicular to the center axis ofdisk portion 50 and intersectsouter circumference 56 ofdisk portion 50.Surface 58 preferably has a diameter larger than the diameter ofbag 42. Although shown as having a generally circular-shaped outer perimeter,disk portion 50 may also be configured to have other shapes, such as hexagonal, octagonal, and the like. For example, ifbag 42 has a hexagonal cross-sectional shape, it may be preferable thatnotch surface 58 also have a hexagonal shape. Similarly, it may also be desirable thatouter circumference 56 also have a hexagonal shape. - Extending from
end surface 52 ofdisk portion 50 is a cylindrically-shapedboss 62 having anouter circumference surface 64. A center axis ofboss 62 substantially coincides with the center axis ofdisk portion 50.Boss 62 may be integrally formed withdisk portion 50, or may be fixedly attached using any suitable method, such as brazing, welding, gluing, and the like. Withend cap 48 attached tobag 42,boss 62 extends intocavity 44, whereincircumference 64 engages the interior periphery ofcavity 44. The outer diameter ofcircumference 64 is preferably larger than the diameter ofcavity 44adjacent end 47 ofbag 42 to produce an interference fit betweenbag 42 andboss 64 when attachingend cap 48 tobag 42. - Attached to an
end surface 66 ofboss 62opposite disk portion 50 is acore pin 68 for formingpassage 28 ofstraight flute drill 22. Althoughcore pin 68 is: shown to have a rod-like shape, it shall be appreciated thatcore pin 68 may also be configured to produce a passage having a different shape, such ashelical core pin 69 shown inFIG. 14 .Core pin 68 may be permanently attached toboss 62 using any suitable means, such as welding, brazing, adhesives, and the like. Alternatively,core pin 68 may be removably attached toboss 62, such as by threading, to enable differently configured core pins to be readily interchanged. - A resilient cylindrically-shaped
first transition member 70 having anouter circumference 72 adjoinsend surface 66 ofboss 62opposite disk portion 50.First transition member 70 provides an elastic transition betweenrigid boss 70 andinterior cavity 44 ofbag 42 to minimize possible flaring of the end of the cutting tool formed usingmold 20. A center axis offirst transition member 70 substantially coincides with the center axis ofboss 62 anddisk portion 50.First transition member 70 includes abore 74 oriented along the longitudinal center axis offirst transition member 70.Bore 74 is engageable withcore pin 68. - With
end cap 48 attached tobag 42,first transition member 70 extends intocavity 44 enablingcircumference 72 of the first transition member to engage the interior periphery ofcavity 44. The outer diameter ofcircumference 72 preferably is larger than the diameter ofcavity 44adjacent end 47 ofbag 42 so as to produce an interference fit betweenbag 42 andfirst transition member 70 when attachingend cap 48 tobag 42.First transition member 70 is preferably made of a resilient material, such as rubber, but may also be made of another material having similar properties. -
End cap 48 can be attached tobag 42 by guidingcore pin 68,first transition member 70, andboss 62 intocavity 44 ofbag 42 untilend surface 52 ofdisk portion 50 contacts endsurface 47 ofbag 42.Bag 42 may be secured to endcap 48 using astrap 112 a.Strap 112 a is preferably placed aroundbag 42 and in alignment withboss 62.Strap 112 a can then be tightened to securebag 42 to endcap 48. -
Mold 20 further includes asecond end cap 76 for sealingend 49 ofbag 42 to prevent fluid from enteringcavity 44 from the exterior ofbag 42.End cap 76 has a generally circular disk-shapedportion 78 having anend surface 80 that is engageable withend 49 ofbag 42 whenend cap 76 is attached tobag 42. An L-shapednotch 82 extends around anentire circumference 84 ofdisk portion 78. Afirst surface 86 ofnotch 82 is oriented substantially parallel to a center axis ofdisk portion 78 and intersectsend surface 80 ofdisk portion 78. Asecond surface 88 ofnotch 82 is oriented substantially perpendicular to the center axis ofdisk portion 78 and intersectsouter circumference 84 ofdisk portion 78.Surface 86 preferably has a diameter larger than the outer diameter ofbag 42. - Although shown as having a generally circular outer perimeter,
disk portion 78 may also be provided with a different shape, such as hexagonal, octagonal, and the like, so as to substantially mirror the shape of the outer periphery ofbag 42. For example, if the outer periphery ofbag 42 has a hexagonal shape, it may be desirable thatnotch surface 86 likewise have a hexagonal shape. Similarly, it may also be desirable thatouter circumference 84 ofdisk portion 78 also have a hexagonal shape. - Extending from
end surface 80 ofdisk portion 78 is a cylindrically-shapedboss 90 having anouter circumference surface 92. A center axis ofboss 90 substantially coincides with the center axis ofdisk portion 78.Boss 90 may be integrally formed withdisk portion 78, or may be fixedly attached using any suitable method, such as brazing, welding, gluing, and the like. Withend cap 76 attached tobag 42,boss 90 extends intocavity 44 so thatcircumference 92 engages the interior periphery ofcavity 44 ofbag 42. The outer diameter ofcircumference 92 ofboss 90 is preferably larger than the interior diameter ofcavity 44 ofbag 42 to produce an interference fit betweenbag 42 andboss 90 when engagingend cap 76 withbag 42. -
Mold 20 further includes a washer-shapedseal 94.Seal 94 is positionable betweenend cap 76 andbag 42 whenend cap 76 is attached tobag 42. Afirst surface 96 ofseal 94 is engagable withsurface 80 ofend cap 76, while anopposite surface 98 ofseal 94 is engageable withend surface 49 ofbag 42.Seal 94 includes a circular-shapedaperture 100 that is engagable withcircumference 92 ofboss 90.Aperture 100 preferably has a diameter smaller than the diameter ofcircumference 92 to produce an interference fit betweenseal 94 andboss 90 when the two components are assemble together.Seal 94 is preferably made from an resilient elastic material, such as rubber, or another material having similar physical properties. - A
second transition member 102 having anouter circumference 104 is insertable withininterior cavity 44 ofbag 42.Second transition member 102 can be engaged withinner cavity 44 ofbag 42 and operates to accomplish the same general function asfirst transition member 70 by providing an elastic transition betweenrigid boss 90 andinterior cavity 44 ofbag 42 to minimize possible flaring of the end of the cutting tool formed usingmold 20. A threadedbore 106 is provided in one end ofsecond transition member 102 for engaging a correspondingly threaded insertion tool 108 (seeFIG. 11 ) that can be used for insertingsecond transition member 102 intocavity 44. Withsecond transition member 102 inserted incavity 44 ofbag 42,outer circumference 104 ofsecond transition member 102 engages the inner periphery ofcavity 44. The outer diameter ofcircumference 104 preferably is larger than the inner diameter ofcavity 44adjacent end 49 ofbag 42 to produce an interference fit betweenbag 42 andsecond transition member 102.Second transition member 102 is preferably made of a resilient material, such as rubber, or alternatively, another material having similar properties. -
Second transition member 102 can be installed incavity 44 ofbag 42 by engaging a threadedend 110 ofinstallation tool 108 with threadedbore 106 ofsecond transition member 102. Withsecond transition member 102 attached toinstallation tool 108,second transition member 106 can be inserted intocavity 44 ofbag 42, after whichinstallation tool 108 can be detached fromsecond transition member 102.Seal 94 can be positionedadjacent end surface 49 ofbag 42 withaperture 100 substantially aligned with the opening tocavity 44 inend 49 ofbag 42.End cap 76 can be attached tobag 42 by guidingboss 90 intocavity 44 ofbag 42 untilend surface 80 ofdisk portion 78 contacts endsurface 49 ofbag 42.Bag 42 may be secured to endcap 76 using a strap 112 b. Strap 112 b is preferably positioned aroundbag 42 and in alignment withboss 90. Strap 112 b can then be tightened to securebag 42 to endcap 48. -
Mold 20 may also include afill sleeve 114 and apressure sleeve 118. The two sleeves are not used simultaneously, with each serving a separate function. Referring also toFIG. 8 , withend cap 76 removed frombag 42, fillsleeve 114 can be positioned overbag 42 prior to fillingbag 42 with apowdered carbide mixture 115, or a like material having properties suitable for producing cutting tools. Fillingbag 42 withcarbide mixture 115 may causebag 42 to expand due to the bag's elastic nature.Fill sleeve 114 operates to limit the amount of expansion that may occur during the filling process.Fill sleeve 114 has a generally hollow tubular shape with an inner diameter sufficiently large to allowfill sleeve 114 to be slid overbag 42.Fill sleeve 114 andbag 42 preferably are substantially the same length. Anend 116 offill sleeve 114 is engageable withsurface 52 ofend cap 48 whenfill sleeve 114 is placed overbag 42.Bag 42 can be filled with a predetermined quantity ofpowdered carbide mixture 115.Fill sleeve 114 can be removed frombag 42 oncecavity 44 is suitably filled withcarbide mixture 115. - Referring also to
FIGS. 9 and 10 ,mold 42 may also include a cylindrically-shapedpressure sleeve 118.Pressure sleeve 118 can be positioned overbag 42 so as to enclose at least a portion of theexterior periphery 120 ofbag 42.Pressure sleeve 118 provides support forbag 42 and helps maintain proper alignment of the bag during the pressure forming processes. Afirst end 122 ofpressure sleeve 118 is engageable withnotch 54 formed inend cap 48 and asecond end 124 is engageable withnotch 82 formed inend cap 76. The diameter of aninner circumference 121 offirst end 122 ofpressure sleeve 118 is larger than the diameter ofsurface 58 ofnotch 54 to enablepressure sleeve 118 to slide oversurface 58 and engagesurface 60 ofnotch 54. Similarly, the diameter ofinner circumference 121 ofend 124 ofpressure sleeve 118 is larger than the diameter ofsurface 86 ofnotch 82 to enablepressure sleeve 118 to slide oversurface 86 and engagesurface 88 ofnotch 82. The inside diameter ofcircumference 121 ofpressure sleeve 118 is also preferably larger than the diameter of theexterior periphery 120 ofbag 24 to produce acircumferential gap 126 betweeninner circumference 121 ofpressure sleeve 118 andexterior periphery 120 ofbag 42. - Each
end pressure sleeve 118 includes a notchedregion regions straps 112 a and 112 b, and allow fluid to entergap 126 formed betweenpressure sleeve 118 andbag 42 during the forming process. One ormore apertures 132 extend through awall 134 ofpressure sleeve 118 for fluidly connecting the exterior region ofpressure sleeve 118 with the interior region of the pressure sleeve. - A cutting tool, such as
straight flute drill 22, can be formed usingmold 20 by assemblingbag 42 to endcap 48.Strap 112 a is not used to attachbag 42 to endcap 48 at this time.Fill sleeve 114 can be slid overbag 42 and end 116 offill sleeve 114 can be engaged withend surface 52 ofend cap 48.Bag 42 can then be filled with a predetermined quantity ofpowdered carbide mixture 115. To helpcompact carbide mixture 115 present incavity 44 ofbag 42,end cap 48, fillsleeve 114, andbag 42 can be placed on a mechanical vibratingplate 134, or another similar device. Vibratingplate 134 includes aplate 135 that can made to vibrate at a predetermined frequency. Vibrating the end cap/fill sleeve/bag assembly (48,114,42) helps to eliminate voids that could form incarbide mixture 115 and preventcavity 44 from being filled with the desired quantity ofcarbide mixture 115.Sleeve 114 can be removed frombag 42 after the bag is filled with the desired quantity ofcarbide mixture 115. - After
bag 42 has been filled withcarbide mixture 115, end 47 ofbag 42 may be secured to endcap 48 usingstrap 112 a.Pressure sleeve 118 is then slid overbag 42 and end 122 ofpressure sleeve 118 is engaged withnotch 54 ofend cap 48. Second strap 112 b is initially loosely installed aroundend 49 ofbag 42.End cap 48 may be secured topressure sleeve 118 by releasably engaging a pair ofclips 131 with a pair ofpockets 133 formed in anend surface 135 ofend cap 48.Second transition member 102 can be attached toinstallation tool 108 and inserted intocavity 44 ofbag 42 to the point whereend surface 136 ofsecond transition member 102contacts carbide mixture 115. -
End 49 ofbag 42 is sealed to prevent fluid from enteringcavity 44 from the exterior region ofbag 42 by positioningseal 94adjacent end 49 ofbag 42.End cap 76 is then attached to end 49 ofbag 42 by guidingboss 92 ofend cap 76 intocavity 44 ofbag 42 untilnotch 82 ofend cap 76 engagesend 124 ofpressure sleeve 118.End cap 76 can be secured to end 49 ofbag 42 by tightening second strap 112 b aroundbag 42.End cap 76 may also be secured topressure sleeve 118 by releasably engaging a pair ofclips 137 with a pair ofpockets 139 formed in anend surface 139 ofend cap 76. - Referring to
FIG. 13 ,carbide mixture 115 can be pressed into a solid form using a knownisostatic press 140, or a similar device.Mold 20 containingcarbide mixture 115 is placed inisostatic press 140, whereupon the isostatic press is activated (see step 142).Isostatic press 140 utilizes a high pressure liquid, preferably operating at a pressure in excess of 20,000 psi, to apply a generally uniform compressive load to at least a portion of the exterior ofmold 20. The high pressure fluid flows throughorifice 132 and notchedregions pressure sleeve 118 intogap 126 formed betweenbag 42 andpressure sleeve 116. The high pressure fluid present ingap 126 exerts a substantially uniform pressure along at least a portion ofexterior surface 120 ofbag 42. The high pressure fluid causesbag 42 to compress radially, compactingcarbide mixture 115 into a cohesive structure.Rigid pressure sleeve 118 preventscarbide mixture 115 from being compressed axially. After compressingcarbide mixture 115 for a predetermined period of time, the high pressurefluid surrounding mold 20 is discharged andmold 20 is removed fromisostatic press 140. -
Bag 42 containing the compressed carbide mixture can be separated frommold 20 by first disengagingclips 131 fromend cap 48 andclips 137 fromend cap 76.Straps 112 a and 112 b can then be released to allowend caps bag 42.Bag 42 can then be withdraw frompressure sleeve 118.Transition member 102 can be removed fromcavity 44 ofbag 42 usinginstallation tool 108. Referring toFIG. 12 and step 144 ofFIG. 13 , a “green state”straight flute drill 22 a, being of substantially the same configuration as straight flute drill 22 (seeFIGS. 6A and 6B ) can be extracted frombag 42 by applying aforce 141 to thefluted end 32 a ofstraight flute drill 22 a to forcestraight flute drill 22 a out through the access opening tocavity 44 located inend 47 ofbag 42. - Continuing to refer to
FIG. 10 , instep 146 cooling passages 38 (seeFIGS. 6A and 6B ), are drilled instraight flute drill 22 a using adrill press 148, or another suitable tool. To ensure proper orientation ofcooling passages 38,straight flute drill 22 a may be placed in a suitably configuredfixture 149. To facilitate machining ofcooling passages 38, it is preferable the cooling passages be drilled whilestraight flute drill 22 a is in a “green state” prior to undergoing heat treatment. Alternatively, the cooling passages may be formed at any other desired stage of the forming process. - After machining
cooling passages 38,straight flute drill 22 a can be placed in apre-sintering furnace 150 preheated to a predetermined temperature, for example 600° F. Heatingstraight flute drill 22 a causes the wax binder to be removed fromstraight flute drill 22 a.Straight flute drill 22 a is maintained at the elevated temperature for a predetermined period of time after which it is removed frompre-sintering furnace 150 and allowed to cool to approximately room temperature. The heat treated straight flute drill is identified by reference number 22 b. - After straight flute drill 22 b has sufficiently cooled, an
outer circumference 152 of straight flute drill 22 b may be ground to achieve a desired surface finish and diameter using aconventional centerless grinder 154, or another suitable apparatus (see step 151). Straight flute drill 22 b can then be heated in a hightemperature sintering furnace 156 preheated to a predetermined temperature instep 155.Sintering furnace 156 is preferably capable of performing a known heating cycle so as to cause the individual particles incarbide mixture 115 to bind together and form a unitary solidstraight flute drill 22 c having certain desirable physical properties that enablestraight flute drill 22 c to function as a cutting tool. If desired,straight flute drill 22 c may undergo further processing instep 158 after being removed from sinteringfurnace 156, such as grinding cutting flutes on anend 36 c ofstraight flute drill 22 c using conventional grinding methods in step. - While various aspects of the mold have been disclosed, it will be appreciated that many other variations may be incorporated without departing from the scope of the present invention. It is intended by the following claims to cover these and any other departures from the disclosed embodiments that fall within the true spirit of the invention. The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
Claims (32)
1. A mold for forming a cutting tool from one or more granulated materials, the mold comprising:
a bag having an internal cavity for receiving a predetermined amount of the granulated material, the internal cavity having a profile substantially corresponding to a shape of the cutting tool;
a first passage connecting the internal cavity to an exterior of the bag; and
a first end cap removeably engageable with the elastic bag for preventing fluidic communication between the exterior of the bag and the interior cavity through the first passage.
2. The mold of claim 1 further comprising:
a cylindrically shaped sleeve enclosing at least a portion of the exterior of the bag, the sleeve having a first end and a second end, the first end being engageable with the first end cap.
3. The mold of claim 2 further comprising:
a second passage connecting the internal cavity of the bag to the exterior of the bag; and
a second end cap removeably engageable with the bag to prevent fluidic communication between the interior cavity and the exterior of the bag through the second passage, and wherein the second end of the sleeve is engageable with the second end cap.
4. The mold of claim 2 further comprising:
a second passage connecting the internal cavity of the bag to the exterior of the bag;
a second end cap engageable with the second end of the bag for preventing fluidic communication between the interior cavity of the bag and the exterior of the bag through the second passage, and wherein the second end of the sleeve is engageable with the second end cap; and
a seal disposed between and adjoining the second end of the bag and the second end cap.
5. The mold of claim 1 , wherein the first end cap further comprises a boss engageable with the interior cavity of the bag.
6. The mold of claim 1 further comprising a first transition member engagable with the internal cavity.
7. The mold of claim 2 , wherein the first end cap includes a notched region for receiving the first end of the sleeve.
8. The mold of claim 1 further comprising a strap for connecting the bag to the first end cap.
9. The mold of claim 5 further comprising a core pin connected to an end surface of the boss and extending therefrom for producing an internal passage in the cutting tool.
10. The mold of claim 5 further comprising a transition member engageable with an end surface of the boss.
11. The mold of claim 2 , wherein the sleeve includes at least one notched region adjoining one of the first and second ends of the sleeve.
12. The mold of claim 2 , wherein a wall of the sleeve defines at least one orifice for fluidically connecting an exterior region of the sleeve with an inner cavity of the sleeve.
13. The mold of claim 2 , wherein an interior surface of the sleeve and an exterior surface of the bag define an annulus for receiving a high-pressure fluid.
14. The mold of claim 1 , wherein the mold is made from a resilient elastic material.
15. The mold of claim 14 , wherein the resilient elastic material is urethane.
16. A molding apparatus for producing a cutting tool from one or more granulated materials, the molding apparatus comprising:
an elongated cylindrically shaped bag defining a hollow internal cavity for receiving a predetermined quantity of the granulated materials, the internal cavity having a profile configured to substantially mirror an external profile of the cutting tool, the bag having a first end surface defining a first passage and a second end surface defining a second passage, the first and second passages connecting an exterior region of the bag with the internal cavity of the bag;
a first end cap having an end surface engageable with the first end surface of the bag for preventing fluid communication between the interior cavity of the bag and the exterior region of the bag;
a second end cap having an end surface engageable with the second end surface of the bag for preventing fluid communication between the interior cavity of the bag and the exterior region of the bag; and
a sleeve enclosing at least a portion of the exterior of the bag, the pressure sleeve having a first end engageable with the first end cap and a second end engageable with the second end cap.
17. The molding apparatus of claim 16 further comprising:
a core pin connected to the first end cap for forming a passage in the cutting tool, wherein the core pin extends into the interior cavity of the bag when the first end is engaged with the first passage of the bag.
18. The molding apparatus of claim 17 , wherein the core pin has a substantially linear rod-like configuration.
19. The molding apparatus of claim 17 , wherein at least a portion of the core pin is configured as a spiral.
20. The molding apparatus of claim 16 , wherein an end of the sleeve is engagable with the end surface of one of the first and second end caps.
21. The molding apparatus of claim 16 , wherein the first end cap includes a notch adjoining the end surface of the first end cap and a circumferential edge surface of the first end cap, and further wherein a first end of the sleeve is engageable with the notch in the first end cap.
22. The molding apparatus of claim 21 , wherein the second end cap includes a notch adjoining the end surface of the second end cap and circumferential edge surface of the second end cap, and further wherein a second end of the sleeve is engageable with the notch in the second end cap.
23. The molding apparatus of claim 1 , wherein the sleeve includes at least one notched region adjoining one of a first and second ends of the sleeve.
24. The molding apparatus of claim 1 , wherein a wall of the sleeve defines at least one orifice for fluidically connecting an exterior region of the sleeve with an inner cavity of the sleeve.
25. The molding apparatus of claim 16 , wherein an inner surface of the sleeve is displaced from an external peripheral surface of the bag, the inner surface of the sleeve and the external peripheral surface of the bag defining a annulus capable of receiving a fluid under high pressure.
26. The mold of claim 16 , wherein the mold is made from a resilient elastic material.
27. The mold of claim 26 , wherein the resilient elastic material is urethane.
28. A method for forming a cutting tool from a granulated mixture of one or more materials, the method comprising the steps of:
assembling a mold by attaching a first end cap having a core pin to a first end of an elastic bag having an interior cavity;
placing a fill sleeve over the bag and engaging an end of the fill sleeve with the first end cap;
filling the interior cavity of the bag with a predetermined quantity of the granulated mixture; and
vibrating the bag, end cap, and fill sleeve assembly while filling the interior cavity of the bag with the granulated mixture.
29. The method of claim 28 further comprising the steps of:
disengaging the fill sleeve from the first end cap and removing the fill sleeve from around the bag;
and wherein the step of assembling the mold further comprises the step of placing a pressure sleeve over the bag and engaging a first end of the fill sleeve with the first end cap, and attaching a second end cap to a second end of the bag, wherein the end cap engages a second end of the pressure sleeve.
30. The method of claim 29 further comprising the step applying a predetermined pressure load substantially uniformly over at least a portion of an exterior of the assembled mold so as to compress the granulated materials into a substantially solid unitary piece.
31. The method of claim 30 , wherein an isostatic press is used to apply the pressure load to the exterior of the assembled mold.
32. The method of claim 29 further comprising the steps of:
disassembling the mold by disengaging the first end cap form the first end of the pressure sleeve and the first end of the bag, and disengaging the second end cap from the second end of the pressure sleeve and the second end of the bag; and
extracting the cutting tool from the bag.
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US12/639,386 US8147736B2 (en) | 2005-01-10 | 2009-12-16 | Molding apparatus and method for making a cutting tool |
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US11/328,797 US20060151904A1 (en) | 2005-01-10 | 2006-01-10 | Molding apparatus and method for making a cutting tool |
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US12/639,386 Expired - Fee Related US8147736B2 (en) | 2005-01-10 | 2009-12-16 | Molding apparatus and method for making a cutting tool |
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JP2020534432A (en) | 2017-09-22 | 2020-11-26 | ラミナ テクノロジーズ ソシエテ アノニムLamina Technologies S.A. | Processes and equipment for manufacturing cutting tools by press |
EP4046751A1 (en) * | 2021-02-22 | 2022-08-24 | Comadur S.A. | Method for manufacturing a cutting tool with lubrication holes with complex shapes and cutting tool with lubrication holes with complex shapes |
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US4655984A (en) * | 1984-10-15 | 1987-04-07 | Champion Spark Plug Company | Method of and apparatus for isostatically pressing a body from particulate material |
US4934919A (en) * | 1987-04-27 | 1990-06-19 | Inax Corporation | Dry-type rubber pressing apparatus |
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Cited By (4)
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US20090274923A1 (en) * | 2008-03-04 | 2009-11-05 | Kenneth Hall | Tools Having Compacted Powder Metal Work Surfaces, And Method |
US20110289736A1 (en) * | 2010-05-25 | 2011-12-01 | High Concrete Group Llc | Method and apparatus for covering an end of a cable extending from a form during the manufacture of molded structural members |
CN111907109A (en) * | 2020-09-03 | 2020-11-10 | 山西金开源实业有限公司 | Dry bag type isostatic pressing machine |
CN114888287A (en) * | 2022-04-08 | 2022-08-12 | 镇江力航新材料科技有限公司 | Pressed compact equipment for processing high-strength beta titanium alloy and using method thereof |
Also Published As
Publication number | Publication date |
---|---|
US20100090362A1 (en) | 2010-04-15 |
US8147736B2 (en) | 2012-04-03 |
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