[0001] The present invention relates to work benches, and its object is to provide a work
bench with a clamping device which is particularly adapted to the gripping of articles
of complex shape.
[0002] United States Patent 4,527,786 discloses a work bench having a pair of vice assemblies
mounted on a frame, each vice assembly having a movable jaw and a fixed jaw, one vice
assembly heing movable towards and away from the other, and with the movable jaws
being capable of swivelling.
[0003] The present invention may be regarded as a development of this arrangement, and provides
improved means whereby objects of irregular shape may be securely gripped.
[0004] Attention may also be drawn to U.S. Patent 2,322,380 which discloses a vice with
split jaws mounted for rotation on a turntable.
[0005] The present invention is defined in the claims appended hereto, and an embodiment
of it will now be described with reference to the accompanying drawings, in which:-
Figure 1 is a diagrammatic plan view of the vice portion of a work table top;
Figures 1-1 and 1-2 are sections respectively along the lines AA and BB of Figure
1;
Figure 1-3 is an isometric drawing of the work bench top of Figure 1;
Figures 2 and 3 are sections along the line BB of Figure 1 showing alternative arrangements
of the operating handles;
Figure 4 is a diagrammatic overall view of the framework of a work bench on which
the clamping arrangement of Figure 1 is mounted;
Fiqure 5 shows a detail of a handle suitable for use in operating the clamp of the
present invention;
and
Figures 6A - 6F are diagrams illustrating the manner in which the clamp of the present
invention clamps an irregular shaped object, in comparison with the clamps of the
prior art.
[0006] Referring now to the drawings, a work bench comprises a rectangular frame 10 forming
the workbench top, and supported on legs 12 which may be arranged to fold for storage.
One pair of opposite sides of the rectangular frame are provided with slots 14,16.
A third side carries a slide 18 along which a pair of jaws 20,22 are independently
movable, each being coupled to its respective lead screw 24,26.
[0007] A second movable slide 28 is parallel to the first slide 18 and similarly carries
a pair of jaws 30,32 each independently operable for movement along the slide by its
respective lead screw 34,36. This second slide is movable towards or away from the
first slide 18 by means of a further lead screw 38, heing kept parallel to the first
by means of pairs of pins 40,42, and 44,46 riding in the slots 14,16.
[0008] Each of the vice jaws 20,22,30,32 is freely rotatable about a vertical axis 50,52,54,56.
This enables each jaw to accommodate itself to the shape of an object being gripped
by the clamping arrangement, so that objects of any shape can be securely held. For
the same purpose, it will be noted each of the jaws of each pair is movable independently
of the other.
[0009] In order to obtain this independent movement, it is necessary for sound design that
the two lead screws of each slide i.e. 24 and 26 for slide 18 and 34,36 for slide
28, should be closely adjacent to one another, and this makes it difficult to provide
both of them with operating handles of adequate size. While the operating handles
could be at opposite ends of the slides, as indicated in Figure 3, it is more convenient
in practice that all four of the lead screws 24,26,34,36 should be operable from the
front of the work bench.
[0010] In the Figures, two alternative means of dealing with this problem are shown. The
arrangement of Figure 2 depends on the appreciation that when the two jaws of a slide
are advanced into position and tightened to grip an object it is only the tightening
of the second of the two that requires any appreciable force to be exerted. It is
therefore possible to provide one of the two leading screws with a relatively small
knob, such as the knurled knob 60 of Figure 2 by which the first jaw to be adjusted
can be brought into position to contact the object being gripped quite lightly, and
the second lead screw is provided with a more substantial handle, extending beyond
the knob 60, and which can then be tightened until the object to held is firmly gripped.
[0011] In a second solution, each of the four lead screws 24,26,34,36, ends in a shank of
non-circular, preferably square, section, and a handle of special construction is
provided to engage these shanks. The handle is shown in part section in Fiqure 5 and
comprises a barrel 64 having a deep recess 66 of corresponding section such as to
engage the shanks of the lead screws. A permanent magnet 68 is inserted deeply into
this recess and secured in position, so that when the handle is applied to the shank
of one of the lead screws the magnet secures it temporarily in position.
[0012] Figures 6A - 6F comprise a series of diagrams showing the manner in which an object
of irregular shape is gripped by the clamping jaws of the present invention and, for
comparison, how a similar object would be held by the prior art arrangements acknowledged
above. In each case, the upper diagram represents the operation of the present invention,
and the lower left and right diagrams represent respectively the operation of the
arrangements of U.S. Patent 4,527,786 and U.S. Patent 2,322,380.
[0013] Attention is drawn particularly to diagram E and F which relate to the butt-joining
of separate sections, an operation for which work benches of this kind are frequently
employed.
1. A work bench having a top (10) comprising a rectangular frame and provided with
clamping means comprising a first slide (18) forming or secured to one member of the
frame, and carrying a pair of vice jaws (20,22) movable relatively to one another,
a second movable slide (28) parallel to the first and carrying a second pair of jaws
(30,32) movable relative to one another, and means (38) for moving the second slide
towards or away from the first, and in which at least one of the vice jaws is rotatable,
characterised in that each jaw is independently movable along its slide, and each
jaw is rotatable about an axis (50,52,54,56) so that the jaws can conform to the shape
of a work piece beinq gripped.
2. A work bench according to Claim 1 in which two opposite sides of the rectangular
top are slotted (14,16) to form guides for the movable slide.
3. A work bench according to Claim 1 or Claim 2 in which the two jaws (20,22,30,32)
on each slide (18,28) are each provided with a separate lead screw (24,26,34,36),
the two lead screws being closely adjacent.
4. A work bench according to Claim 3 in which one of the said lead screws of each
slide is provided with a knob (60) small enough to clear the second lead screw, while
the second lead screw is provided with an operating handle (62) extending beyond the
knob.
5. A work bench according to Claim 3 in which each of the lead screws ends in a shank
of non-circular section, and a handle having a barrel (64) with a recess (66) of corresponding
shape is provided with a permanent magnet (68) inserted at the bottom of the recess
so as to secure the handle temporarily on a lead screw shank.