Patent Grant
9126344
The present invention relates to a precision tool and particularly to precision cutting nippers and to a process for making the same.
Precision tools and particularly precision cutting nippers and pliers are generally intended for particular application fields, such as horology, electronics, jewelry, medicine, where it is often required to be able to handle and cut wires which may be very thin—e. g. of the size of a human hair or smaller—with a very high quality of the cut, which substantially does not leave marks on the sheared surface.
The precision degree of these cutting nippers may be for example determined by the rake and, based on the cutting precision, is usually identified by three different designations, which correspond to three different cutting precisions, namely flush, semi-flush and ultra-flush.
The tool portion intended for cutting is made of a special material, such as a hard material, e.g. widia, also known as cemented carbide.
The Applicant has observed that, because of the costs, in the known systems only the tool portion intended for cutting is made of a special material, whereas the remaining portion is made of a less expensive material. The two portions are joined together by means of braze welding, after which the blades are sharpened by grinding for obtaining the quality and cutting precision desired for the tool.
The Applicant has further observed that the braze welding operation deserves great care and any error, even minimal, in this operation results in a not perfect alignment of the tool blades and thus in an item to be scrapped.
The Applicant has further observed that the braze welding is time-consuming and expensive.
Finally, the Applicant has noticed that any defect or fracture that arises in any of the tool portions, either after the braze welding or sharpening operations or in use, causes the whole tool to be scrapped.
The Applicant has found that it is possible to overcome the abovementioned problems with a precision tool in which the braze welding operation for coupling the two tool portions can be avoided and the critical aspects of the sharpening operation can be limited.
In a first aspect thereof, the invention thus relates to a precision tool comprising two prongs adapted to be associated with each other;
characterized by comprising coupling means for removably coupling at least one operating portion with at least one support portion.
The precision cutting nippers and pliers are made with a precision approaching 5/1000 of a millimeter.
The tight tolerances required in the manufacture of the tool are an essential condition for the proper operation of the same.
The dimensional accuracy in the construction and in the manufacturing process allows the tool to be defined as a “precision tool”.
The particular application fields, such as horology, electronics, jewelry and medicine, in which the cutting nippers and/or pliers are used involve geometric, functional and efficiency constraints which only precision tools meeting the above definitions can satisfy.
Within the framework of the present invention, by the expression precision tool it is defined, referring to
The present invention, in the abovementioned aspect, may have at least one of the preferred features which are hereinafter described.
Conveniently, the screw-nut system comprises at least one screw and at least one calibrated nut and is adapted to generate a predetermined friction and a substantially constant movement while the cutting or bending portion moves from the working position to the rest position and vice versa.
Preferably, the coupling means comprise at least one clamp screw and at least one threaded seat for receiving the clamp screw.
Advantageously, the threaded seat is formed on the support portion.
Preferably, the coupling means comprise a self-centering device.
Advantageously, the self-centering device is shaped so as to lock into position the operating portion relative to the support portion along three mutually orthogonal directions, when such portions are assembled with each other.
Conveniently, the self-centering device comprises at least one tapered portion formed on the operating portion adapted to mate with a corresponding tapered portion formed on the support portion.
Advantageously, the self-centering device comprises a shoulder, extending substantially at a right angle, formed on the operating portion, and a head element, formed on one end of the support portion; said head element being dimensioned and shaped so as to abut against the shoulder, when the operating portion is coupled with the support portion.
Preferably, the shoulder and the head element are flat.
Conveniently, the operating portion is made of cemented carbide.
According to another aspect, the present invention relates to a process for making a precision tool of the type comprising two prongs adapted to be associated with each other;
the process comprising the following steps:
Preferably, the step of grinding and sharpening the said two operating portions is carried out before the step of removably coupling the two operating portions with the two prongs by means of the said coupling means.
Further features and advantages of the invention shall become more apparent from the detailed description of some preferred, although not exclusive, embodiments of a precision tool according to the present invention.
Such description shall be presented hereinafter with reference to the accompanying drawings, provided only for indicating, and thus non-limiting, purposes, wherein:
Referring to
In particular, the cutting tool 100 is provided with two prongs 2, 2′ adapted to be associated with each other, by means of a precision member 6.
Each prong 2, 2′ comprises a grip portion 4, 4′ and a cutting portion 5, 5′.
Each prong 2, 2′ is associated, by means of a precision member 6, with the other prong.
The precision member is a screw-nut system adapted to generate a predetermined friction and a substantially constant movement while the cutting portion moves from the working position to the rest position and vice versa.
The precision member 6 comprises a slotted screw of the torx type and a calibrated nut.
The precision member 6 separates and defines the grip portion 4, 4′ and the cutting or bending portion 5, 5′ in each prong 2, 2′.
Each prong 2, 2′ is associated, by means of the precision member 6, with the other prong so as to move the cutting portions 5, 5′ from a working position, in which the cutting portions 5, 5′ contact each other, to a rest position (shown in
As better shown in
Each operating portion 7, 7′ comprises at least one cutting blade or cutting edge 8, 8′, i.e. the tool portion adapted to interact with the material to be cut.
Within the framework of the present invention, by the expression precision tool it is defined, referring to
Preferably, the operating portion is made of a special material such as for example widia, also known as cemented carbide, carboloy or hard metal.
Cemented carbide or widia is used in machining and consists of hard particles of tungsten carbide embedded in a metal matrix. Generally, the cemented carbide or widia is made by means of a sintering process, in which, as it is known, fine powders and components are mixed, pressed and then heated in a vacuum furnace at temperatures between 1300° and 1600° C. In the furnace a high pressure is maintained, so that the powder grains aggregate to form an integral piece. The sintering process make the tungsten carbide and the cobalt (matrix) to melt together, producing a dense “hard metal”.
After sintering the strength of the material is such that only diamond machining—a special micro-machining operation which is relatively expensive, since it does not allow to remove large amounts of material—is possible. Widia is used for making tools to be used for applications which require a high hardness material (cutting, crumbling, etc.). Tools made of hard metal or widia have a higher hardness compared to those made of high-speed steel (HV 1500 instead of HV 1000) and withstand higher cutting temperatures (1000° C. instead of 600° C.).
According to an important aspect of the present invention, the tool 100 has coupling means 9 for removably coupling at least one operating portion 7, 7′ with at least one support portion 3, 3′.
An operating portion 7, 7′ is removably coupled with a support portion 3, 3′.
Preferably, the coupling means 9 comprise at least one clamp screw 10, 10′ and at least one threaded seat 11, 11′ for receiving the clamp screw 10, 10′.
This allows the braze welding operation which is performed in the known precision tools to be avoided and the sharpening operation by means of grinding to be performed before assembling.
Referring to the embodiment of
Preferably, the screw is a slotted screw of the torx type.
This choice ensures a greater precision compared to a different coupling system and a large clamp torque.
For obtaining a precise coupling between operating portion and support portion, the precision cutting tool 100 has a self-centering device.
The self-centering device is shaped so as to lock into position the operating portion 7, 7′ relative to the support portion 3, 3′ along three mutually orthogonal directions, as indicated by axes X-X; Y-Y; Z-Z in the figure.
Referring to the embodiment shown in
In the embodiment shown in the figures the tapered portion 12, 12′ has a substantially triangular shape, while the corresponding tapered portion 13, 13′ formed on the support portion 3, 3′ has a dovetail shape, in other words it reproduces in negative the triangular shape of the tapered portion 12, 12′.
The tapered portion 12, 12′ is dimensioned and shaped for coupling substantially perfectly with the corresponding tapered portion 13, 13′ formed on the support portion 3, 3′.
Referring to the embodiment shown in
Referring to
The portions 12, 12′ and thus the portions 13, 13′ could also have other shapes without departing from the scope of protection of the invention.
The tapered portions 12, 12′ as well as the corresponding tapered portions 13, 13′ are ground by means of hi-speed Haas milling machines with precisions approaching 5/1000 of a millimeter.
In order to further increase the precision of the coupling between operating portion 7, 7′ and support portion 3, 3′, the self-centering device comprises a shoulder 14, 14′ extending substantially at a right angle, formed on the operating portion 7, 7′, and a head element 15, 15′ formed on one end of said support portion 3, 3′.
Each head element 15, 15′ is dimensioned and shaped so as to abut against a shoulder 14, 14′ when the operating portion 7, 7′ is coupled with the support portion 3, 3′.
Preferably, the shoulders 14, 14′ and the head elements 15, 15′ are flat.
Still referring to
The shoulders 14, 14′ are ground by means of numerical control sharpening machines especially intended for hard metal machining and the head elements 15, 15′ are as well machined by means of hi-speed Haas milling machines with precisions approaching 5/1000 of a millimeter.
In a coupled condition each operating portion 7, 7′ is partially facing and superimposed to the respective support portion 3, 3′; this kind of coupling prevents a movement of the components with respect to the Z-Z axis, i.e., referring to
In
In detail, on each operating portion 7, 7′ the position of the tapered portion 12, 12′ is swapped with the position of the head elements 15, 15′ so that the head elements 15, 15′ are moved to an inner position and the tapered portions 12, 12′ are moved to a more outer position.
Similarly, on each support portion 3, 3′ the position of the tapered portion 13, 13′ is swapped with the position of the shoulder 14, 14′ so that the latter are moved to an inner position and the tapered portions 13, 13′ are moved to a more outer position.
Referring to the embodiment shown in
The process for making a precision tool according to the present invention comprises the steps of:
making two prongs 2, 2′;
making two operating portions 7, 7′;
grinding and sharpening the blades 8, 8′ of the two operating portions 7, 7′;
providing coupling means 9;
removably assembling the two operating portions with the two prongs 2, 2′ by means of said coupling means 9.
The assembling step is carried out by introducing the clamp screws 10, 10′ in the suitable threaded seats 11, 11′ so as to associate an operating portion 7, 7′ with the respective support portion 3, 3′.
In detail, according to a particularly advantageous aspect of the present invention, the step of sharpening the blades 8 of the two operating portions is carried out before the step of removably coupling the two operating portions 7, 7′ with the two prongs 2, 2′ by means of the coupling means 9.
The present invention has been described with reference to some embodiments thereof. Many modifications can be introduced in the embodiments described in detail, still remaining within the scope of protection of the invention, which is defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0508/11 | Mar 2011 | CH | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 496584 | Taft | May 1893 | A |
| 1168051 | Bernard | Jan 1916 | A |
| 1181871 | Graham | May 1916 | A |
| 1405028 | Stead | Jan 1922 | A |
| 1662108 | Fay | Mar 1928 | A |
| 2677177 | Herckelbout | May 1954 | A |
| 4130938 | Uhlmann | Dec 1978 | A |
| 5987752 | Swanstrom, Jr. | Nov 1999 | A |
| 20110289784 | Jones | Dec 2011 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20120266467 A1 | Oct 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61468185 | Mar 2011 | US |
