Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Making composite or hollow article
Reexamination Certificate
2000-12-12
2003-05-13
Jenkins, Daniel J. (Department: 1742)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Making composite or hollow article
C419S009000, C419S011000, C425S078000
Reexamination Certificate
active
06562288
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cutting blade, and in particular, to a method and an apparatus for manufacturing high speed cutting blades used for cutting stones, metal, concrete, asphalt, bricks, earthen pipes, etc., and a cutting blade manufactured by the same.
2. Description of the Related Art
In a building site or a civil engineering site, cutting blades of a disk shape are generally used as cutting tools for cutting stones, metal, concrete, asphalt, bricks, earthen pipes, etc. Each of those cutting blades comprises a disk-shaped steel core with a predetermined thickness made of a high speed tool steel such as carbon tool steel, low carbon tool steel or the like, and a plurality of cutting segments made of a diamond-metal powder mixture, usually, by mixing diamond particles and metal powder of a specific ingredient, forming the mixture into a predetermined shape and sintering the same at a high temperature. The cutting segments are fixedly attached to the periphery of the disk-shaped steel core at regular intervals, usually by welding.
As shown in
FIG. 1
, the conventional method for manufacturing those cutting blades mainly comprises the steps of: preparing a diamond-metal powder mixture by mixing diamond particles having a predetermined size with metal powder having a predetermined ingredient and size; forming the diamond-metal powder mixture into cutting segments of a predetermined shape by pressing the mixture in a forming pattern of a forming die using pressurized punching means; sintering the formed cutting segments in a separate sintering furnace; and welding the sintered cutting segments to the periphery of the disk-shaped steel core at regular intervals using a separate welding apparatus. Each manufacturing step of the conventional method is independently performed in a separate station, respectively.
In addition, before welding the sintered cutting segments to the periphery of the steel core, the conventional method for manufacturing the cutting blades further comprises the steps of: barrel-finishing to remove burrs or flashes undesirably formed at the peripheral edges of the cutting segments in the forming step; and radius grinding to conform the inner curvature of the sintered cutting segments to the outer curvature of the periphery of the steel core to which those cutting segments are to be welded.
In general, upon completion of the manufacturing process by completely welding the cutting segments throughout the periphery of the disk-shaped steel core at regular intervals, further steps of dressing the surfaces of the cutting segments, and painting or marking on the surface of the cutting blade may optionally be performed.
According to the conventional method, each step of manufacturing is independently performed using separate apparatus, equipments or devices, such as forming die, sintering furnace, barrel-finishing machine, radius grinder, and welding machine, which are separately installed in different places.
FIG. 2
schematically illustrates a typical forming die for forming the cutting segments in a conventional apparatus for manufacturing the cutting blades. Referring to
FIG. 2
, in general, the forming die comprises: an upper press having an upper punch assembly
11
consisting of a plurality of vertically reciprocating punches
12
; a lower press having a lower punch assembly
13
consisting of a plurality of vertically reciprocating punches
14
; and a die assembly
18
having forming patterns
15
of a cross-sectional shape corresponding to that of the punches of the upper and lower presses. On the upper surface of the die assembly
18
, forming material filling feeders
16
are placed at left and right sides, respectively, so as to be movable in horizontal direction by hydraulic cylinders
17
. The forming material filling feeders
16
are connected to separate powder material supplying sources (not shown).
In addition to the forming die as described above, the conventional apparatus for manufacturing the cutting blades also comprises a sintering furnace, a barrel-finishing machine, a radius grinder, a welding machine and so on, which are separately installed in different places and perform independent functions. All of them are commercially available in the field of the present invention and therefore no drawings and detailed description will be provided herein.
In manufacturing cutting blades according to the conventional method and the conventional apparatus, first, diamond-metal powder mixture is prepared by mixing diamond particles of a predetermined size and metal powder of a predetermined ingredient and size. The diamond-metal powder mixture is filled into the forming patterns
15
of the die assembly
18
of the forming die by the forming material filling feeders
16
horizontally reciprocating on the upper surface of the die assembly
18
, and then formed into cutting segments of a predetermined shape by pressing the mixture in the forming pattern
15
with the vertically reciprocating punches
12
by moving down the upper punch assembly
11
of the upper press. At this time, the vertically reciprocating punches
14
of the lower punch assembly
13
of the lower press are maintained in a stationary state at a desired position.
Moving upwardly the upper punch assembly
11
apart from the forming pattern
15
, and then moving upwardly the lower punch assembly
13
with a predetermined distance, the cutting segments formed as described above are released out of the forming pattern
15
by the upwardly moving punches
14
of the lower punch assembly. The formed and released cutting segments are then moved to a sintering station from the forming die, and put into a separately installed sintering furnace (not shown) and sintered under a predetermined temperature for a predetermined time period. The sintered cutting segments are then moved to a welding station and welded to the periphery of the disk-shaped steel core at regular intervals using a separate welding machine (not shown).
However, prior to welding the sintered cutting segments to the periphery of the disk-shaped steel core, it is necessary to perform barrel-finishing in a separate station so as to remove burrs or flashes undesirably formed at the peripheral edges of the cutting segments in the forming step, and radius grinding in a separate station so as to conform the inner curvature of the sintered cutting segments to the outer curvature of the periphery of the steel core to which those cutting segments are to be welded.
In the conventional method for manufacturing the cutting blades, as described above, the step of forming the cutting segments of a predetermined shape by pressing the diamond-metal powder mixture, the step of sintering the formed cutting segments, and the step of welding the sintered cutting segments to the periphery of the disk-shaped steel core are independently performed in separate stations. Furthermore, prior to welding the sintered cutting segments to the periphery of the disk-shaped steel core, the step of barrel-finishing to remove the burrs or flashes formed at the peripheral edges of the cutting segments in the forming step, and the step of radius grinding to conform the inner curvature of the sintered cutting segments to the outer curvature of the periphery of the steel core should also be independently performed in separate places. Therefore, the conventional method requires to move half-finished or intermediate products in every step of manufacturing and to perform all the steps of manufacturing at separate stations using separate apparatus, equipments or devices, and as a result, the conventional method not only consumes a long period of time for manufacturing but also incurs a considerable amount of loss in materials, energy and manpower.
The conventional manufacturing apparatus also requires, in every step of manufacturing, to use separate apparatus, equipments or devices separately installed in different stations, which results in requiring a large space or separated places to install the en
Dickstein , Shapiro, Morin & Oshinsky, LLP
Jenkins Daniel J.
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