This application claims the benefit of priority to international patent application number PCT/FI2019/050449, filed on Jun. 11, 2019, which claims the benefit of Finland patent application No. 20185661, filed on Jul. 27, 2018, the complete disclosures of which are hereby incorporated by reference for all purposes.
The present disclosure relates to shearing tools, and particularly to hand operated shearing tools, such as scissors.
The cutting capacity of traditional scissors intended for cutting fabric, leather etc. is limited by the force keeping the blades together. When this force is not high enough, the blades are forced apart and the material to be cut will be squeezed between the blades. If the blades are rigid enough and the geometry of the insides of the blades allows, this can be overcome by tightening the blades against each other at the pivot to allow a high cutting capacity, but then the “idle” cutting force will be great and the scissors awkward to use.
Document U.S. Pat. No. 3,460,251 A discloses a hand tool such as a pair of shears comprises a pair of pivotally-connected blades, a first handle rigid with a first blade and a second handle connected to a second blade through a coupling comprising rolling elements, e.g. balls resting in recesses in the coupling parts, the coupling being effective, when the tool is cutting or shearing a piece of material, to bias the blades towards one another in a direction perpendicular to the direction of their relative movement with a force which is related to the resistance offered by the material. In one embodiment, the coupling between a blade and its handle, comprises balls resting partly in recesses formed in a plate secured to the handle and partly in recesses formed in the blade, relative movement of the handles causing the balls to ride partially out of the recesses and thereby generate a force in a direction normal to the direction of the relative movement to bias the blades towards one another. In another embodiment, a blade is rigid with a handle and carries a pivot on which the blade is pivoted. The blade is movable relative to the blade by a coupling comprising balls nesting in frusto-conical recesses in a plate and in the upper face of the blade, the plate having a shoulder engageable by a finger on a plate carried by a movable handle pivoted to the handle.
Document GB 431240 A discloses scissors, in which the cutting edges are forced together on the application of increased force at the handles during cutting.
An object of the present disclosure is to provide a shearing tool so as to provide an alternative way to improve the cutting capacity of a shearing tool.
The object of the disclosure is achieved by a shearing tool which is characterized by what is stated in the independent claim. The preferred embodiments of the disclosure are disclosed in the dependent claims.
The disclosure is based on the idea of providing a hand operated shearing tool, comprising a first unit comprising a first blade, the first blade comprising a first cutting edge; and a second unit comprising a second blade and a second handle connected to the second blade at a proximal end of the second blade, the second blade comprising a second cutting edge. The second unit is connected rotatably to the first unit about a first rotational axis defined by a first pivot, the first pivot comprising a first pin penetrating the first blade and the second blade. The first pin is connected to the first blade so that displacement of the first blade in relation to the first pin in a direction parallel with the first rotational axis is prevented. The second unit is arranged to be rotated in relation to the first unit about the first rotational axis between an open position of the shearing tool and a closed position of the shearing tool. The second handle is connected to the second blade so that rotational movement of the second handle in relation to the second blade about a second rotational axis is allowed. The second rotational axis is defined by a second pivot interacting with the second blade and the second handle and being arranged at a distance from the first rotational axis in a direction away from the cutting edge contact point. The first pin is arranged to penetrate the second handle through a through hole arranged in the second handle. The diameter of the through hole is greater than the diameter of the first pin for allowing movement of the second handle in relation to the second blade in a direction transversal to the first rotational axis. The through hole has a frusto-conical shape at the end of the through hole opening in the direction away from the second blade. The first pivot comprises a frusto-conical shape arranged coaxially with the first pin for interacting with the frusto-conical shape of the through hole. As a result, the second handle is arranged to exert a compressive force to the second blade due to a shearing force between the second handle and the second blade when the shearing tool is moved from the open position towards the closed position. Due to the compressive force, the second blade is driven towards the first blade at the cutting edge contact point for increasing the cutting capacity of the shearing tool.
An advantage of the shearing tool of the disclosure is that its structure is simple requiring only a few parts, resulting in easier manufacturing. It is also a more efficient way to increase the cutting capacity of a shearing tool.
In the following the disclosure will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which
The disclosure relates to a hand operated shearing tool. For example, the hand operated shearing tool is a pair for scissors or a pair of shears, such as a pair of fabric scissors or sewing scissors, grass shears, hedge shears or plate shears.
The hand operated shearing tool comprises a first unit 1 comprising a first blade 11. The first blade 11 comprises a first cutting edge 112. Optionally the first unit 1 comprises also a first handle 12 fixed to the first blade 11 at a proximal end 111 of the first blade 11.
The hand operated shearing tool comprises a second unit 2 comprising a second blade 21 and a second handle 22 connected to the second blade 21 at a proximal end 211 of the second blade 21. The second blade 21 comprises a second cutting edge 212.
The second unit 2 is connected rotatably to the first unit 1 about a first rotational axis R1 defined by a first pivot 3. The first pivot 3 comprises a first pin 31 penetrating the first blade 11 and the second blade 21. The first pin 31 is connected to the first blade 11 so that displacement of the first blade 11 in relation to the first pin 31 in a direction parallel with the first rotational axis R1 is prevented. Preferably the first pin 31 is attached to the first blade 11. For example, the pivot 3 is formed by a screw that is screwed to a hole in the first blade 11. The second unit 2 is arranged to be rotated in relation to the first unit 1 about the first rotational axis R1 between an open position of the shearing tool and a closed position of the shearing tool. In the open position, the first cutting edge 112 and the second cutting edge 212 are in an angle of at least 45°. In the closed position, the first blade 11 and the second blade 21 are essentially parallel.
At least one of the first blade 11 and the second blade 21 is curved and the first blade 11 and the second blade 21 are biased against each other so that the first cutting edge 112 and the second cutting edge 212 are in constant contact at a cutting edge contact point P when the hand operated shearing tool is moved between the open position and the closed position. The object to be cut is cut at the cutting edge contact point P. As the hand operated shearing tool is moved from the open position to the closed position, the cutting edge contact point P moves along the first cutting edge 112 and the second cutting edge 212. The first blade 11 and the second blade 21 exert a cutting edge force towards each other at the cutting edge contact point P. The cutting capacity of the shearing tool is directly proportional to the cutting edge force.
The proximal end 111 of the first blade 11 is located on one side of the first pivot 3 away from the cutting edge contact point P. The proximal end 211 of the second blade 21 is located on one side of the first pivot 3 away from the cutting edge contact point P.
The second handle 22 is connected to the second blade 21 so that rotational movement of the second handle 22 in relation to the second blade 21 about a second rotational axis R2 is allowed. The second rotational axis R2 is defined by a second pivot 4 interacting with the second blade 21 and the second handle 22. According to an embodiment, the second pivot 4 comprises a second pin 41 penetrating the second blade 21 and the second handle 222, as illustrated in
The first pin 31 is arranged to penetrate the second handle 22 through a through hole 221 arranged in the second handle 22. The diameter of the through hole 221 is greater than the diameter of the first pin 31 for allowing movement of the second handle 22 in relation to the second blade 21 in a direction transversal to the first rotational axis R1. The through hole 221 has a frusto-conical shape at the end of the through hole 221 opening in the direction away from the second blade 21. In other words, the diameter of the through hole 221 increases towards the end of the through hole that is in the direction away from the second blade 221. For example, the angle of the frusto-conical shape of the through hole 221 is 40° to 50°, preferably 42° to 48°, more preferably 45°. The first pivot 3 comprises a frusto-conical shape arranged coaxially with the first pin for interacting with the frusto-conical shape of the through hole 221. In other words, the diameter of the first pivot 3 increases in the direction away from the second handle 22. According to an embodiment, the frusto-conical shape of the first pivot 3 is integral with the head 32. According to an alternative embodiment, the frusto-conical shape of the first pivot 3 is provided by a frusto-conical washer 33 arranged coaxially with the first pin 3, as illustrated in
According to an embodiment of the disclosure, the second handle 22 comprises a frusto-conical shape arranged coaxially with the through hole 221 at the opposite side of the second handle 22 in relation to the second blade 21 for forming, together with the frusto-conical shape of the through hole 221, an annular protrusion 222. The formed annular protrusion 222 has an annular ridge where the frusto-conical shape of the through hole 221 and the frusto-conical shape of the second handle 22 meet. For example, the angle of the ridge of the annular protrusion 222 is 80° to 100°, preferably 84° to 96°, more preferably 90°. The first pivot 3 comprises an annular groove 34 arranged coaxially with the first pin 31 and corresponding to the shape of the annular protrusion 222 for receiving the annular protrusion 222 in the annular groove 34. In other words, the annular groove 34 is formed by two coaxial frusto-conical sections, the outer of which is inverted. This embodiment has been illustrated in
According to an alternative embodiment of the disclosure, the second handle 22 comprises an annular groove 223 arranged coaxially with the through hole 221 at the opposite side of the second handle 22 in relation to the second blade 21, and the first pivot 3 comprises an annular groove 34 arranged coaxially with the first pin 31. The annular groove 223 of the second handle 22 and the annular groove 34 of the first pivot 3 are formed by two coaxial frusto-conical sections, the outer of which is inverted. According to an embodiment, the annular groove 34 of the first pivot 3 is integral with the head 32. According to an alternative embodiment, the annular groove 34 of the first pivot 3 is provided by a washer 35 arranged coaxially with the first pin 31, as illustrated in
The second handle 22 is arranged to exert a compressive force F2 to the second blade 21 due to a shearing force F1 between the second handle 22 and the second blade 21 when the shearing tool is moved from the open position towards the closed position. In other words, the frusto-conical shape of the through hole 221 and the first pivot 3, the shearing force F1 between the second handle 22 and the second blade 21 is converted into the compressive force F2. Due to the compressive force F1, the second blade 21 is driven towards the first blade 11 at the cutting edge contact point P for increasing the cutting capacity of the shearing tool.
Number | Date | Country | Kind |
---|---|---|---|
20185661 | Jul 2018 | FI | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FI2019/050449 | 6/11/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2020/021159 | 1/30/2020 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
1005661 | Shirt | Oct 1911 | A |
1100876 | Henderson | Jun 1914 | A |
2239851 | Lincoln | Apr 1941 | A |
2290203 | Nikonow et al. | Jul 1942 | A |
2696045 | Blodgett | Dec 1954 | A |
2856687 | Beckmann et al. | Oct 1958 | A |
3460251 | Somervell et al. | Aug 1969 | A |
4074430 | Sugiyama | Feb 1978 | A |
4133107 | Vogel | Jan 1979 | A |
4715122 | Linden | Dec 1987 | A |
4982500 | Ramani | Jan 1991 | A |
5440813 | Roskam | Aug 1995 | A |
5628116 | Kohno | May 1997 | A |
5689888 | Linden | Nov 1997 | A |
5694694 | Roskam | Dec 1997 | A |
7810242 | Lynch | Oct 2010 | B1 |
D700029 | Roberts | Feb 2014 | S |
10695921 | Wong | Jun 2020 | B2 |
20150375385 | Nix et al. | Dec 2015 | A1 |
20220126466 | Adachi | Apr 2022 | A1 |
Number | Date | Country |
---|---|---|
2832459 | Nov 2006 | CN |
101605637 | Jul 2012 | CN |
102922542 | Feb 2013 | CN |
106660217 | May 2017 | CN |
43 02 921 | Aug 1994 | DE |
29910126 | Sep 1999 | DE |
2 540 459 | Jan 2013 | EP |
124699 | Dec 2012 | FI |
0 431 240 | Jul 1935 | GB |
0 431 240 | Jul 1935 | GB |
0 924 741 | May 1963 | GB |
S5357583 | May 1978 | JP |
H08-257259 | Oct 1996 | JP |
M524776 | Jul 2016 | TW |
WO-2019239008 | Dec 2019 | WO |
WO-2020021159 | Jan 2020 | WO |
Entry |
---|
International Search Report and Written Opinion for International Application No. PCT/FI2019/050449, dated Aug. 30, 2019, 10 pages. |
Search Report for Finnish Application No. 20185661, dated Feb. 25, 2019, 1 page. |
Extended European Search Report for EP Application No. 19842341.0, dated Apr. 11, 2022, 5 pages. |
Number | Date | Country | |
---|---|---|---|
20210308883 A1 | Oct 2021 | US |