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(11) | EP 0 037 673 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Unitary tool mechanism |
| (57) A tool is formed in one piece, suitably from resilient plastics material and comprises
a first head (2) from which extend a pair of divergent handles (12,14) having at their
free ends respective resilient beams (16, 18) extending inwardly towards the head
(2). The beams (16, 18) at their convergent ends are joined with a head (4) spaced
from the head (2), and are arcuately convex towards each other. On pivotal closure
of the tool by bending of the arms (12,14), the beams (16,18) progressively engage
from their upper ends and drive the head (4) towards the head (2). |
[0001] This invention relates to a tool having a pair of arms secured at a head for pivotal movement between open and closed conditions, and a resilient member between the arms arranged to bias them towards an open condition.
[0002] Such tools are commonly used as hand tools or pliers for applying force or a cutting action to a work piece, and are also used as mechanisms in assemblies.
[0003] It is an object of the invention to provide a tool of simple unitary structure which may be made economically, for example by moulding or extrusion.
[0004] According to the present invention a tool having a pair of arms secured at a head for pivotal movement between open and closed conditions and a resilient means between the arms arranged to bias them towards an open condition is characterised in that the head, the arms and the resilient means comprise a unitary structure formed in one piece from resilient material, the arms extending from the head in divergent manner and the resilient means comprising a pair of beams extending from respective portions of the arms spaced from the head, inwardly between the arms towards the head to a second head portion, the beams being adapted, on movement of the arms together, to engage progressively along their lengths from the second head portion.
[0006] The invention will now be described with reference to the accompanying partly diagrammatic drawings, in which:-
Figure 1 is an elevation of a tool for applying force between a pair of jaw members and in an open condition;
Figure 2 is a view similar to that of Figure 1 but with the tool in a partially closed condition;
Figure 3 is a side elevation of the tool of Figure 1;
Figure 4 is a section taken on the line.4 - 4 of Figure 1;
Figure 5 is a sectional elevation of a modified tool mounted on a support rail;
Figure 6 is a fragmentary section taken on the line 6 - 6 of Figure 5;
Figure 7 is a fragmentary elevation of the head portion of a further modified tool;
Figure 8 is a fragmentary section taken on the line 8 - 8 of Figure 7;
Figure 9 is a fragmentary sectional elevation of a yet further modified tool in an open condition; and
Figure 10 is a fragmentary elevation similar to that of Figure 9 but with the tool in a partially closed condition.
[0007] The tool of Figures 1 to 4 comprises a first head 2 defining a lower jaw surface 6 and a second head 4 defining an upper jaw surface 7 spaced below surface 6. The surface 6 is defined at the roof of a cavity in the first head 2 between side walls 8, 10 adapted slidably to receive head 4 between them.
[0008] A pair of arms 12, 14 extend from the head 2 downwardly on opposite sides of the cavity in divergent manner. Initial portions of the arms 12, 14 are of progressively decreasing thickness towards lower thickened end portions 12A, 14A defining handles which can be gripped in a hand in conventional manner.
[0009] The second head 4 is supported from the lower ends of the arias 12, 14 by a pair of arcuate resilient beams 16, 18, convex towards each other and converging upwardly with upper end portions 16B, 18B closely adjacent and integral with the head 4.
[0010] The heads 2, 4, the arms 12, 14, and the beams 16, 18 are integrally formed as a unitary structure, suitably by moulding or by extrusion from a resilient plastics material having a high yield strength. It will be understood that a number of tools may be formed from a single moulding or extrusion having a cross section corresponding to the elevation of Figure 1, and individual tools severed transversely of the length of moulding or extrusion.
[0011] In operation, closure of the handle portions 12A, 14A together effects pivotal movement about the head 2 by bending of the thinner portions of the arms 12, 14. The arcuate beams 16, 18 progressively engage at their upper portions 16B, 18B and are supported against each other as seen in Figure 2, effectively to increase their length in the direction of arrow 20 and drive the head 4 into the cavity of head 2 towards jaw surface 6.
[0012] The sides 8, 10 of the cavity and the engaged portions of beams 16, 18 resist lateral displacement of the head 4 and maintain its orientation. A workpiece, not shown, may be engaged between the jaw faces 6, 7 and subject to compression. The beams 16, 18 are correspondingly subject to compression and the arms 12, 14 to tension. Resilience of the beams and the arms serves to open the tool when the handles are released.
[0013] In the modified tool of Figures 5 and 6, like reference numerals refer to similar parts as described with reference to Figures 1 to 4. The head 4 at its underside between the beams 16, 18 is formed with a cylindrical socket 22 extending through the head 4 transversely of its line of action. The socket has a restricted opening between the beams 16, 18 and receives a complementary cylindrical head 26A of an upright rail 26 which extends downwardly between the beams 16, 18 and is stiffened by a transverse flange 28 at a rear side of the tool.
[0014] In operation of the tool the beams 16, 18 are flattened against the rail 26 as the handles 12, 14 are closed, and the rail serves to support the beams.
[0015] In the embodiment of Figures 7 and 8, in which like reference numerals again refer to similar parts as described with reference to Figures 1 to 4, the head 4 is formed at its rear side with an upwardly directed extension 4A which extends slidably through a recess 2A in a rear side of the head 2.
[0016] The extension 4A at its upper end is formed with a further head portion 4B presenting a lower jaw face 4C spaced from and opposed to a jaw face 2B presented by the upper side of head 2.
[0017] In the embodiment of Figures 7 and 8, a workpiece may be gripped between jaw faces 6 and 7 on closure of the tool or between surfaces 4C, 2B on opening of the tool handles.
[0018] In the embodiment of Figures 9 and 10 in which like reference numerals again refer to similar parts as described in connection with Figures 1 to 4, the head 2 is formed with an upright bore in which the lower, open end of a cylinder 30 is secured. An upright rod 36 is secured to the head 4 and extends coaxially through the lower end of the cylinder 30. A washer type piston 38 is secured at the upper end of the rod 36, and the upper closed end 32 of the cylinder is formed with an outlet 34.
1. A tool having a pair of arms secured at a head for pivotal movement between open
and closed conditions and a resilient means between the arms arranged to bias them
towards an open condition, characterised in that the head (2), the arms (12, 14) and
the resilient means (16, 18) comprise a unitary structure formed in one piece from
resilient material, the arms (12, 14) extending from the head (2) in divergent manner
and the resilient means (16, 18) comprising a pair of beams (16, 18) extending from
respective portions of the arms (12, 14) spaced from the head (2), inwardly between
the arms (12, 14) towards the head (2) to a second head portion (4), the beams (16,
18) being adapted, on movement of the arms (12, 14) together, to engage progressively
along their lengths from the second head portion (4).
2. A tool as claimed in Claim 1, characterised in that the beams (16, 18) are arcuately
convex away from their respective arms (12, 14)..
3. A tool as claimed in Claim 1 or in Claim 2, characterised in that the arms (12,
14) are flexible relative to the head (2) on closure of the arms (12, 14) together
to obtain the pivotal action by bending of the arms (12, 14).
4. A tool as claimed in any preceding claim, characterised in that the first head
(2) is formed with a recess (6, 8, 10) between the arms (12, 14) and adapted slidably
to receive the second head (4) on closure of the arms (12, 14), the second head (4)
being spaced from the first head (2) when the arms (12, 14) are in an open condition.
5. A tool as claimed in any preceding claim, characterised in that the second head
(4) is formed between the beams (16, 18) with a recess (22) having a restricted lower
entry between the beams-(16, 18), a support rail (26) having an enlarged head portion
(26A) engaging the recess (22) with the rail (26) extending between the beams (16,
18) such that on closure of the arms (12, 14) together, the beams (16, 18) progressively
flatten against opposite sides of the rail (26).
6. A tool as claimed in Claim 4, characterised in that the second head (4) is formed
with an extension (4A) slidably overlapping the first head portion (2) and formed
with a third head portion (4B) spaced from the first head portion (2) on a side remote
from the second head portion (4).
7. A tool as claimed in Claim 4, characterised in that the second head portion (4)
is formed with an extension (36) projecting through an aperture (30) in the first
head portion (2).