The present invention relates to a method and a device for manufacturing a tool and a tool made by the method.
It is previously known through for example International Publication WO 98/28455 to press material powder, such as wolfram carbide (WC) together with cobalt (Co), between a punch and a die, and subsequently to sinter the material such that the binder metal is melted and binds the carbides to form tool material for chip removing machining. The known technique brings about a plurality of drawbacks. The powder give off dust and the formed green body (pressed but not sintered material) will not endure handling to any degree. Furthermore the chip flutes must be ground and the method requires time and energy. The problems have partly been solved by the injection molding of hard metal mixed in a carrier such as indicated in U.S. Pat. No. 5,947,660. The method of injection moulding brings a high degree of freedom concerning geometry but brings costly investments in moulds.
Through U.S. Pat. No. 4,779,440 a tool is previously known for forming a blank for a helix drill. An extruded drill blank having chip flutes of constant pitch along the circumference of the blank is obtained by heating a hard metal powder to extrusion temperature, pressing the heated powder blank under high energy consumption through a space defined by a mandrel and a nozzle while rotating the blank. The blank is guided during the extrusion past a helical ridge provided at the inside of the nozzle, to shape helical chip flutes along the blank as the blank rotates. A drawback of the known technique is that the chip flutes are obtained along the entire length of the blank.
One object of the present invention is to provide a method, a device and a tool, whereby the drawbacks of the known technique are eliminated.
Another object of the present invention is to provide a method and a device whereby the lengths of the chip flutes can be determined.
These and other objects have been achieved by a method and apparatus for manufacturing a tool as well as a tool made by the method.
The method of manufacturing a rotary tool for chip removing machining comprises the steps of:
The apparatus is adapted to be mounted to an extrusion machine for shaping a mixture received from the extrusion machine into a rotary tool for chip forming machining. The apparatus comprises a housing which is adapted to be mounted to an extrusion machine and forms a through-passage for conducting the mixture in a feed direction. The through-passage defines a center axis. A nozzle is provided which forms a restriction in the passage. A die is disposed downstream of the nozzle and includes a through-hole. At least one jaw is situated adjacent a downstream end of the die and is movable toward the axis to an inner position in engagement with the mixture received from the die for applying a shape thereto. The die is movable away from the axis to an outer position to avoid applying the shape thereto.
The invention also pertains to a rotary tool made by the above-described method.
The objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment thereof in connection with the accompanying drawings in which like numerals designate like elements and in which:
The preferred embodiment of a tool according to the invention shown in
In
The drill or the milling cutter is manufactured as follows. Hard metal powder having a certain cobalt content and a carrier, for example a polymer or a plastic, is mixed and shaped into pellets or granulates. The content of binder lies within the interval of 1–10 percent by weight. The expression “cobalt” shall here be understood as a metallic binder that alternatively can be exchanged for or include other metals, for example nickel, Ni. Subsequently the mixture or compound is preheated to a temperature suitable for the particular mixture and is inserted in an extrusion machine 50. The machine 50, see
Then the hot compound reaches the core 33 and passes along opposite sides thereof through the two substantially semi-circular openings formed at respective ones of the sides. Rearwardly (downstream) of the core in the feed direction F the compound fuses into a cylindrical body. If the pins 35 are provided in the core, then spaces are formed in the body, which later will constitute flush channels. The pins are made long enough to allow the compound to cool such that fusion within the flush channels is avoided. Subsequently the compound reaches the jaws 40, 41 which are disposed in an inner position. The compound travels through the recesses 42 defined by the jaws 40, 41 whereby the compound, due to the geometries of the ridges 43, travels helically through the jaws and obtains the cross-section of a helix drill. The ridges 43 need not be identical. When the compound comes out from between the jaws it cools quickly due to the surrounding temperature, and the blank continues to extrude until the fluted part is sufficiently long. Subsequently the jaws 40, 41 are radially separated to outer positions away from the compound such that a cylindrical non-fluted shank portion is formed. The length of the shank part is determined either by how long the extrusion is continued or by when the jaws are displaced inwardly such that the formation of a new blank is initiated. In the latter case two or more blanks are continuous. The solidified blank can then be cut or simply be broken, for example by hand, into suitable lengths, e.g., in intervals of 5–10 times its diameter.
Then the blank is heated in a separate furnace such that the carrier is burned off and such that the binder metal melts and binds the carbides. Then further machining takes place, such as grinding for example at edge portions, shank portion and clearance surfaces.
With the present method and device a tool can be produced with or without chip flutes and with or without a shank portion and allows a simple handling to a low cost. This can be done without generating dust. Furthermore unsuccessful blanks can simply be remilled and recycled in the extruder. In addition, at least one jaw could be used to make marks in the shank portion of the blank where a plane is to be ground for chucking. Thereby the grinding volume can be minimized.
The invention is in no way limited to the above described embodiments but can be varied freely within the scope of the appended claims. Thus the invention can be used also for making solid end mills. The tool can be coated with layers of for example A12O3, TiN and/or TiCN.
Number | Date | Country | Kind |
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9902059 | Jun 1999 | SE | national |
This application is a divisional of application Ser. No. 09/586,974, filed on Jun. 5, 2000.
Number | Name | Date | Kind |
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4351631 | Gessner et al. | Sep 1982 | A |
4671763 | Weiler | Jun 1987 | A |
4779440 | Cleve et al. | Oct 1988 | A |
5438858 | Friedrichs | Aug 1995 | A |
5792490 | Geiger | Aug 1998 | A |
5947660 | Karlsson et al. | Sep 1999 | A |
5989482 | Sagawa | Nov 1999 | A |
6176699 | Franjo et al. | Jan 2001 | B1 |
Number | Date | Country |
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0 458 774 | Nov 1991 | EP |
WO9828455 | Jul 1998 | WO |
Number | Date | Country | |
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20020110432 A1 | Aug 2002 | US |
Number | Date | Country | |
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Parent | 09586974 | Jun 2000 | US |
Child | 10128410 | US |