EP2055431A1 - Hand Operated Gripping Tool - Google Patents
Hand Operated Gripping Tool Download PDFInfo
- Publication number
- EP2055431A1 EP2055431A1 EP08167998A EP08167998A EP2055431A1 EP 2055431 A1 EP2055431 A1 EP 2055431A1 EP 08167998 A EP08167998 A EP 08167998A EP 08167998 A EP08167998 A EP 08167998A EP 2055431 A1 EP2055431 A1 EP 2055431A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- jaw unit
- workpiece
- jaw
- hand operated
- gripping tool
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B7/00—Pliers; Other hand-held gripping tools with jaws on pivoted limbs; Details applicable generally to pivoted-limb hand tools
- B25B7/06—Joints
- B25B7/10—Joints with adjustable fulcrum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B7/00—Pliers; Other hand-held gripping tools with jaws on pivoted limbs; Details applicable generally to pivoted-limb hand tools
- B25B7/12—Pliers; Other hand-held gripping tools with jaws on pivoted limbs; Details applicable generally to pivoted-limb hand tools involving special transmission means between the handles and the jaws, e.g. toggle levers, gears
Definitions
- the invention relates to hand operated gripping tools and particularly to hand operated gripping tools that are adjustable to any size of workpiece within the range of the jaws of the tool.
- One form of hand operated gripping tool to which the invention is particularly applicable is pliers of the type generally referred to as water pump pliers or slip joint pliers.
- Existing water pump pliers have the common characteristic of jaws offset at an angle to the pliers handles and a pivot post, in the form of a bolt or rivet, mounted in the area rearward of the jaw on one of the handles and projecting through an elongate slot on the other handle.
- means for enabling selective spacing of the distance between the jaws may take the form of spaced apart ridges or teeth provided along the inside long edge of the slot and adapted for incremental selective binding engagement with the pivot post.
- Another well known way of providing distance adjustment between the jaws in such pliers is to provide spaced apart arcuate ridges on the facing surfaces of the slot for engagement by the pivot post.
- All such tools require a two-handed operation to adjust the jaw spacing the size of a workpiece to be gripped between the jaws. This adjustment involves pulling the handles apart to permit the pivot post to slide along the slot to move the movable one of the jaws to a position that provides a jaw spacing approximating to the size of the workpiece that is to be gripped.
- pliers are adapted to slideably close upon a workpiece in response to manual closing of the handles and, in response to contact with the workpiece, automatically lock against further sliding action by engaging suitable teeth and thereby shift from a sliding to a pivoting mode whereby continued exertion of manual force on the handles increases the gripping action upon the workpiece.
- the gripping action of the known pliers is a function of the relationship between the length of the operating handles and the length of the jaws from the pivot post, which is typically in a ratio of around 5:1.
- the result is that a considerable portion of the torque applied to the operating handles is required to grip the workpiece, meaning there is often insufficient torque available to shift a tight workpiece.
- the invention provides a hand operated gripping tool comprising a first jaw unit having a workpiece engaging portion, a second jaw unit having a workpiece engaging portion and movable relative to said first jaw unit such that a variable size workpiece receiving space is defined between said workpiece engaging portions and a handle for applying a force to said second jaw unit, said second jaw unit being engageable with a reaction surface such that, in use, in response to a said force applied by said handle the workpiece engaging portion thereof is forced against a workpiece received in said workpiece receiving space, at least one of said first and second jaw units comprising a bend promoting portion configured to promote limited bending of the jaw unit in a direction away from the other jaw unit in response to a reaction force generated by engagement with a said workpiece disposed between said first and second jaw units.
- the hand operated gripping tool may comprise a camming device connected with said pivotal handle for causing said second jaw unit to engage said reaction surface.
- the hand operated gripping tool may comprise a fixed handle connected with said first jaw unit and a pivotal link pivotally connected to each said handle and provided with a slide pin that is slideable in a slot defined by one said handle.
- the hand operated gripping may have a locking member that is engageable with said pivotal link for locking said second jaw unit.
- the locking member may be provided with formations for cooperably engaging formations provided on said pivotal link.
- the hand operated gripping tool may comprise a biasing device arranged to bias said locking member to an operative position.
- the invention also includes a hand operated gripping tool comprising a first jaw unit, a second jaw unit, a first cam associated with said first jaw unit, a pivotal handle for applying an operating force to said first jaw unit and a second cam associated with said pivotal handle, said first and second jaw units being cooperable to define a variable size space for receiving a workpiece and said first and second cams being operable in response to a said operating force to cause said first and second jaw units to grip a said workpiece that is positioned in said variable size space, at least one of said first and second jaw units comprising a flexure promoting portion configured to promote flexure of the jaw unit away from said variable size space in response to a reaction force generated by a workpiece gripped between said first and second jaw units in said variable size space.
- the first jaw unit may comprise a connection portion between said first cam and said pivotal handle and said flexure promoting portion may be defined by said connection portion, said flexure promoting portion defining a fulcrum about which said first jaw unit can flex away from said variable size space.
- the second jaw unit may comprise a said flexure promoting portion, said flexure promoting portion comprising a recess provided in an outer side surface of said second jaw unit that faces away from said variable size space
- the invention also includes a hand operated gripping tool comprising first jaw means, second jaw means cooperable with said first jaw means to define an variable size workpiece receiving space, support means on which said first jaw means is slideable for varying the size of said workpiece receiving space and a pivotable lever means, said first jaw means and said pivotable lever means each being provided with engagement means for engaging respective parts on said support means such that pivoting movement of said lever means in one direction causes said first jaw means to move against a workpiece that is positioned in said workpiece receiving space at least substantially in contact with said first and second jaw means so as to grip said workpiece and said first jaw means being configured to permit limited bending movement away from said workpiece receiving space in response to a reaction force generated by a workpiece gripped between said first and second jaw units in said variable size space.
- the engagement means and respective parts on the support means may be arranged such that over a range of said pivoting movement in said one direction said movement generates a progressively increasing gripping force.
- At least one of said engagement means may be arranged to cooperate with the respective said part on said support means such that pivoting movement in said one direction beyond said range of said movement locks said first jaw means in position against a workpiece received in said workpiece receiving space.
- the hand operated gripping tool may comprise automatic locking means for locking said first jaw means independently of engagement between said engagement means and the respective parts on said support means when, in use, said lever means is moved in said one direction beyond a locking position.
- the automatic locking means may be selectively positionable in an inoperative position.
- the first jaw means may comprise corrugation means for permitting said bending movement.
- the corrugation means may comprise at least one arch formed in said first jaw means, said arch arching in the plane of the first jaw means and generally towards said workpiece receiving space.
- FIGs 1 to 4 illustrate a first embodiment of a hand operated gripping tool in the form of pliers 1.
- the pliers 1 comprise a fixed jaw unit 2a, a movable jaw unit 2b, a fixed handle 3 and a pivotal handle 4.
- Each jaw unit 2a, 2b has a workpiece engaging portion provided with jaw gripping profiles 2g, 2f.
- the movable jaw unit 2b can be moved relative to the fixed jaw unit 2a by operation of the pivotal handle 4 to provide a variable size workpiece receiving space between the jaw gripping profiles 2g, 2f.
- the jaw units 2a, 2b, fixed handle 3 and pivotal handle 4 can be laminate structures.
- the uppermost (as viewed in the drawings) laminations have been removed to reveal internal features of the pliers 1.
- the fixed jaw unit 2a is connected with a support member 3a for the movable jaw 2b.
- the support member 3a extends transverse to the fixed jaw unit 2a (in this embodiment the jaw support member extends approximately perpendicular to the fixed jaw unit).
- the movable jaw unit 2b is able to slide along the support member 3a to vary the size of the workpiece receiving space.
- the support member 3a defines a first clamp, or reaction, surface 3b and a second clamp, or reaction surface 3c.
- the first and second clamp surfaces 3b, 3c are disposed in oppositely facing spaced apart relation.
- the fixed handle 3 is connected with an end of the support member 3a such that the support member extends between and connects the fixed handle 3 to the fixed jaw unit 2a.
- the movable jaw unit 2b is a laminate structure comprising a jaw centre member 2h and an extension portion comprising two elongate link members 5e.
- the uppermost link member 5e (as viewed in the drawings) has been removed to reveal internal features of the pliers 1.
- the movable jaw unit 2b comprises a cam surface 2c, which is defined by the jaw centre member 2h and is engageable with the first clamp surface 3b.
- the link members 5e are attached to the sides of a jaw centre member 2h such that the jaw centre member is sandwiched between the link members.
- the portions of the link members 5e that are attached against the sides of the jaw centre member 2h are shaped to correspond to the profile of the jaw centre member and so include jaw gripping profiles 2f, 2g.
- the link members 5e extend from the jaw centre member 2h and are disposed in opposed spaced apart relation to define a gap therebetween.
- the support member 3a extends through the gap defined between the link members 5e.
- a pivotal handle 4 is pivotally connected with movable jaw unit 2b by means of a pivot pin 6 at a connection location adjacent the respective free ends of the link members 5e.
- the link members 5e comprise a bend, or flexure, promoting portion 5f.
- the bend promoting portion 5f is disposed between the first clamp surface 3b and the connection location at which the pivotable handle 4 is connected to the movable jaw unit 2b by the pivot pin 6.
- the bend promoting portion 5f extends between the cam surface 2c and second clamp surface 3c.
- the bend promoting portion 5f comprises a bowed, or corrugated, section that is bowed in the general direction of the fixed jaw unit 2a.
- the bowing is in the plane of the link members 5e.
- the pivotal handle 4 is provided with a toothed pivotal handle cam 4at, which is positioned on the pivotal handle adjacent the pivot pin 6 such that when the pivotal handle pivots on the pivot pin, the cam 4at pivots about the axis of the pivot pin.
- the teeth of the toothed pivotal handle cam 4at engage a toothed slip shoe 17t that engages and is slideable along the second clamp surface 3c.
- a pivotal link 12 extends between the fixed handle 3 and pivotal handle 4.
- the pivotal link 12 is pivotally connected to the fixed handle 3 by a pivot pin 12b that is slideably received in a slot 3e defined in the fixed handle 3.
- the slot 3e extends in the lengthways direction of the fixed handle 3 and when the uppermost (as viewed in the drawing) lamination of the handle is in place, cannot be seen.
- the pivotal link 12 is pivotally connected to the pivotal handle 4 by a pivot pin 12a.
- a biasing member in the form of a tension spring 8 is connected to the pivot pin 12a and a location on the pivotal handle 4 and is arranged to bias the pivotal handle to the position shown in Figure 1 .
- the pliers are shown in a fully open condition in which the workpiece receiving space defined between the jaw units 2a, 2b is at its maximum extent.
- the pliers 1 are provided with an automatic locking device that comprises teeth 22 provided on the end of the pivotal link 12 adjacent the pivot pin 12a and a locking member 24.
- the locking member 24 is pivotally mounted on the pivotal handle 4 on a pivot pin 26.
- the pivot pin 26 is fixed to the pivotal handle 4 and extends through a lengthways extending slot 27 ( Figure 2 ) provided in the locking member 24.
- the locking member 24 has a thumb tab 28 for actuation by a user of the pliers 1. When the uppermost lamination of the pivotal handle 4 is in place, the thumb tab 28 is the only portion of the locking member 24 that is visible.
- the side of the member facing away from the pivotal handle pin 6 is provided with teeth 30 for engaging the teeth 22 on the pivotal link 12.
- teeth 30 On the other side of the locking member 24 opposite the teeth 30, there is a recess that houses an end of a resilient member, which in this embodiment is compression spring 32.
- the opposite end of compression spring 32 is held in a recess 34 provided in the pivotal handle 4.
- the toothed end of the locking member 24 is provided with a nose-like projection 36 that engages in recesses 38, 40 provided in the pivotal handle 4 to locate the locking member 24 in its inoperative and operative positions respectively.
- the compression spring 32 biases the locking member 24 to the operative position shown in Figures 1 and 2 in which the projection 36 engages in the recess 40 and the member is able to automatically engage the teeth 22 provided on the end of the pivotal link 12.
- the locking member is held in a withdrawn position in which it cannot engage with the pivotal link 12.
- the locking member 24 can be locked in a withdrawn inoperative position.
- the thumb tab 28 is used to slide the locking member 24 outwardly with respect to the pivotal handle 4 to withdraw the projection 36 from the recess 38.
- the compression spring 32 acts against the toothed end of the locking member to move the locking member to the operative position shown in Figures 1 and 2 in which it is ready to automatically engage the pivotal link 12.
- the teeth 30 on the locking member 24 are shown engaging the teeth 22 on the pivotal link 12, thereby locking the jaw units 2a, 2b in the position shown.
- the teeth 22, 30 are shaped such that as the pivotal link 12 pivots from the position shown in Figure 1 to the position shown in Figure 2 , they automatically engage in the manner of a ratchet.
- the biasing force provided by the compression spring 32 presses the teeth 30 into the teeth 22, thereby ensuring that locking engagement is maintained.
- the lock can be released by pushing down (as viewed in Figure 2 ) on the thumb tab 28 to cause the toothed end of the locking member 24 to pivot clockwise to release the pivotal link 12 and allow free movement of the pivotal handle 4 relative to the fixed handle 3.
- the thumb tab 28 is released, the toothed end of the locking member 24 is returned to the position shown in Figure 1 so that the locking member is ready to automatically engage the teeth 22 of the pivotal link 12.
- the bend or flexure promoting portion 5f has been found to provide advantages in the operation of the pliers 1. It will be appreciated that when the movable jaw unit 2b engages a workpiece trapped between the jaw gripping profiles 2f, 2g, it can require a considerable force input from the user to force the moveable jaw unit hard 2b into the workpiece so that the teeth 22 on the pivotal link 12 fully engage the teeth 30 on the locking member 24. This is particularly so if the jaw units 2a, 2b and workpiece are made of a hard material and are rigid. Where the respective parts are hard and rigid, there is a risk of the teeth 22, 30 not fully engaging and the lock slipping.
- an optional recess, or cut-out, 2m is shown provided in the fixed jaw unit 2a. This allows additional flexure of the jaw units 2a, 2b to further reduce the user input force needed to lock the jaw units 2a, 2b in firm engagement with a workpiece.
- the configuration of the bend promoting portion 5f and, when provided, the recess 2m can be varied considerably to provide the degree of flexure required.
- the bend promoting portion of 5f comprises a single bow or arch directed in the general direction of the workpiece receiving space. It is envisaged that further arches, undulations or corrugations in the plane of the link members 5e could by provided.
- the degree of allowed bending should be relatively small, otherwise, the pliers 1 will not be able to provide a satisfactory gripping action. The degree of flexure required and allowable for satisfactory operation on the pliers 1 can readily be determined by experiment.
- first and second clamp surfaces 3b, 3c provided on the support member 3a are not parallel. Instead, the first clamp surface 3b tapers towards the second clamp surface 3c as the two surfaces approach the fixed jaw 2a.
- This tapering of the support member 3a is shown in Figure 4 .
- the wedge effect this provides causes the movable jaw unit cam 2c to act more quickly and to lock better. This also allows the jaw angle to be less likely to result in a partial closure when gripping a thin workpiece as the thinning of the support member 3a towards the fixed jaw unit 2a can cancel out the effect of any rotation of the toothed pivotal handle cam 4at against the toothed shoe 17.
- Figure 5 illustrates a second embodiment of a hand operated gripping tool in the form of pliers 1.
- the pliers 1 are shown in a closed condition gripping a fastener-type workpiece between the jaw units 2a, 2b.
- the uppermost (as viewed in the drawing) link member 5e has been omitted to reveal internal parts of the pliers 1.
- the support member 3a extends generally perpendicular to the first jaw unit 2a and has first and second clamp surfaces 3b, 3c that are disposed in substantially parallel spaced apart relation.
- a slot 3d extends in the lengthways direction of the support member 3a.
- a slide pin 7 extends through the slot 3d generally perpendicular to the plane of the support member 3a and is held in respective bushes provided in the link members 5e. The slide pin 7 is able to slide along the slot 3d as the second jaw unit 2b slides along the support member 3a.
- a resilient member in the form of a tension spring 8 is housed within the slot 3d. One end of the spring 8 is secured to the fixed jaw 2a by a spring post 9. The opposite end of the resilient member 8 is secured to the slide pin 7. The spring 8 pulls the second jaw unit 2b towards the first jaw unit 2a such that that pliers 1 are biased towards a closed condition and will provide a light clamping force on the workpiece 11a prior the application a force F to the pivotal handle 4.
- the pivotal handle 4 is provided with an integral cam 4a that acts against the second clamp surface 3c of the support member 3a to cause rotation of the cam 2c of the second jaw unit 2b against the first clamp surface 3b.
- the pivotal arm 4 is also provided with respective stop surfaces 4d arranged to be engageable with stops 5d that project from the link members 5e and serve to limit movement of the pivotal handle 4 away from the fixed handle 3.
- Figures 5 and 6 shows a third embodiment of a hand operated gripping tool in the form of pliers 1 with the uppermost (as viewed in the drawing) link arm 5e removed in order to show internal parts of the tool.
- the slip shoe 17 is shown to be in the form of a cross.
- the slip shoe 17 is held between the cam 4a on the pivotal handle 4 and the second clamp surface 3c by the arms 17a of the slip shoe engaging in respective slots (not shown) in the link members 5e.
- the slip shoe 17 is thus constrained to move with the movable jaw unit 2b as it slides on the support member 3a.
- the cam-to-cam distance D2 between the cams 4a, 2c is indicated.
- Figure 7 shows the third embodiment with the pivotal handle in the fully closed position and the jaws units 2a, 2b clamping a workpiece 11c in the form of two plate-like members.
- the movement of the pivotal handle 4 to the fully closed position has rotated the cam 4a past the slip shoe to bring a locking surface 4b has into firm contact with the second clamp surface 3c via the slip shoe 17.
- the operation of the clamp 4a on the pivotal handle has moved the movable jaw unit 2b on the cam surface 2c to bring a locking portion 2d of the movable jaw unit 2b into engagement with the first clamp surface 3b above the centre of the pivot pin 6 a distance D1.
- This arrangement prevents the pivotal handle 4 from moving outwards with respect to the fixed handle 3 unless manually moved in that way. This locks the pliers 1 in the closed position gripping the workpiece 11c.
- Figure 8 is a plan view of the fourth embodiment of a hand operated gripping tool in the form of pliers 1. Again, an uppermost (as viewed in the drawing) link member 5e of the movable jaw unit 2b has been omitted to show internal features of the pliers 1.
- the fixed handle 3 is joined directly to the fixed jaw unit 2a.
- the resilient member 8 is not within an elongate slot in the support arm 3a. Instead, it is held between respective spring posts 9 fitted to the fixed jaw unit 2a and movable jaw unit 2b.
- the resilient member 8 is arranged to bias the movable jaw unit 2b towards the fixed jaw unit 2a and position the cam 4a on the pivotal handle 4 against the second clamp surface 3c when the pliers 1 is in a rest position. In this embodiment, there is no slip shoe, so the cam 4a bears directly against the second clamp surface 3c.
- Figures 9 to 11 show a fifth embodiment of a hand operated gripping tool in the form of pliers 1.
- the fixed handle top laminate 3g, pivotal handle top laminate 4e and top link member 5e are shown removed.
- FIG 9 the pliers 1 are shown at rest.
- the resilient member 8 is acting on the pivotal handle 4 and pivotal link 12 to urge the movable jaw unit 4b down the support member 3a away from the fixed jaw unit 2a. This moves the cam surface 2c off the first clamp surface 3b to open a gap Ga.
- a stop 4d on the pivotal handle 4 acts against a stop 5d on the link member 5e to limit the movement of the pivotal handle.
- the cam 4a on the pivotal handle 4 is off of the second clamp surface 3c.
- FIG 11 the pivotal handle 4 and pivotal links are shown in a fully operated position causing the jaw units 2a, 2b to clamp on a tubular workpiece 11b.
- the force F applied to the pivotal handle 4 has caused the pivot pin 12b to travel down the slot 3e in the fixed handle 3, thereby extending the resilient member 8.
- This action rotates the movable jaw unit 2b on the cam surface 2c driving the locking portion 2d towards the first clamp surface 3b further improving the gripping action of the jaw units 2a, 2b on the workpiece 11b.
- This allows considerable torque to be applied to the rotation of the workpiece 11b, whilst a reduced force F is required to ensure the jaw units 2a, 2b continue to grip the workpiece 11b.
- Figures 12 and 13 illustrate a sixth embodiment of a hand operated gripping tool in the form of pliers 1.
- the uppermost (as viewed in the drawings) link member 5e is shown removed to reveal internal parts of the pliers 1. In this embodiment, there is no fixed handle 3.
- the jaw units 2a, 2b are shown opened by applying an axial force F to the support member 3a to move the fixed jaw unit away from the movable jaw unit 2b.
- the axial force F acts against the biasing force of the resilient member 8, which is held between respective spring posts 9 fixed to the jaw units 2a, 2b.
- the resilient member 8 pulls the jaw units 2a, 2b to lightly clamp a workpiece 11a between the jaw units.
- a force F applies a torque to the pivotal handle 4 to cause the cam 4a on the pivotal handle to act on the second clamp surface 3c via a slip shoe 17. This causes the movable jaw unit 2b to pivot on the cam surface 2c to provide a firm grip on the workpiece 11 a.
- the embodiments shown in Figures 5 to 8 have a fixed jaw unit 2a that is attached to a fixed handle 3 via an elongate support member 3a and a movable jaw unit 2b that is attached via one or more link members 5e to a pivotal handle 4 such that it can slide and pivot relative to the fixed jaw 2a.
- the support member 3a is an elongate bar with parallel oppositely facing clamp surfaces 3b, 3c, although, as shown in Figure 4 , the support member may taper towards the fixed jaw unit. With the pivotal handle 4 in the open position, the movable jaw unit 2 band pivotal handle 4 are free to slide to and fro along the support member 3a.
- an elongate slot 3d within the support member 3a containing a resilient member in the form of an extension spring 8 that has one end attached to the movable jaw unit 2b by a slide pin 7 and the other end attached to the fixed jaw unit 2a by a spring post 9 a.
- the extension spring 8 acts to urge the two jaw units 2a, 2b towards a closed position.
- the pivotal handle 4 is manually moved away from the fixed handle 3 and propelled along the elongate bar 3a to allow a workpiece 11 to enter between the jaw units 2a, 2b. Releasing the pivotal handle 4 allows the spring 8 to close the jaw units 2a, 2b on the workpiece 11.
- the pivotal handle 4 has a cam locking portion 2d that can be moved into engagement with the support member 3a at a location positioned above the cam surface 2c (ie nearer to the fixed jaw unit 2a).
- the grip between the jaw units 2a, 2b and the workpiece 11 is increased as the cam 4a is rotated against the second clamp surface 3c causing the movable jaw unit 2b to rotate towards the fixed jaw unit until the locking portion 2d comes into contact with the first clamp surface 3b.
- the cam 4a on the pivotal handle 4 is suitably proportioned and has sufficient force exerted upon it by the actuation of the pivotal handle 4 towards the fixed handle 3, the workpiece 11 will be firmly clamped between the jaw units 2a, 2b.
- the degree of clamping action on the workpiece 11 will be directly related to the gripping action angle Ga or movable jaw 2b rotation on the cam surface 2c until the locking portion 2d is clamped against the first clamp surface 3b. In use, this can result in additional force being exerted outwardly upon the jaw units 2a, 2b.
- the pliers 1 can be manually operated by the operation of the pivotal handle 4 only.
- the grip on the workpiece 11 can be increased by manually increasing the force F applied between the pivotal and fixed handles 3, 4.
- the gripping function can be released by reversing the operating direction of the pivotal handle 4 (ie moving it away from the fixed handle 3) until gripping force of the jaw units 2a, 2b on the workpiece 11 is approximately that of the extension spring 8. This makes it possible to reposition the pliers on the workpiece in a manner similar to a ratchet wrench.
- a further locking function can be incorporated in the pliers 1 by the provision of a generally flat locking portion or portions 4b adjacent to the cam 4a on the pivotal handle 4 such that movement of the cam 4a past the second clamp surface 3c brings the locking portion or portions 4b into engagement with the clamping surface.
- a slip shoe 17 can be provided.
- the slip shoe 17 can be retained within apertures in the link members 5e to ensure it is correctly positioned between the cam 4a and the second clamp surface 3c. In use the cam 4a then slips on the smooth surface of the slip shoe 17.
- FIG. 9 to 11 incorporates a pivotal link 12 between the fixed and movable handles 3, 4.
- a resilient member 8 pulls the pivotal link 12 to a position in which its movable end and the associated pivot pin 12a are at the end of the slot 3e in the fixed handle that is closest to the jaw units. This holds the jaws in the open position shown in Figure 9 .
- Initial operation of the handles 3, 4 from the position shown in Figure 9 results in the pivotal handle 4 pivoting around the pivot link and pivot pin 12a, rapidly closing the jaw units 2a, 2b onto the workpiece 11 until the jaw units 2a, 2b abut the workpiece 11.
- pivotal handle 4 forces the movable end of the pivotal link 12 and the associated pivot pin 12b along the slot 3e against the return force generated in the resilient member 8. This allows the pivotal handle 4 to rotate further towards the fixed handle 3. Moving the pivotal handle 4 towards the fixed handle 3 causes the cam 4a to act on the second clamp surface 3c. The movable jaw unit 2b then pivots on the cam surface 2c, further closing the jaw units 2a, 2b onto the workpiece 11 and ensuring the workpiece is sufficiently gripped prior to using the pliers on the workpiece.
- a fixed handle 3 is not necessarily required, provided the resilient member 8 is strong enough to ensure closure of the jaw units 2a, 2b against a workpiece 11 during the initial actuation of the pivotal handle 4 until the cam 4a has sufficient grip on the second clamp surface 3c to allow movable jaw unit 2b to pivot on the cam surface 2c.
- the geometrical proportions of the pliers 1 can be varied to suit many different applications and gripping forces.
- each jaw unit that is provided with a bend promoting portion should be made of a material (typically a steel) that is sufficiently resilient to cope with the bending without being permanently deformed or otherwise damaged by it.
- Embodiments of the invention include a set of pliers for applying a torque to rotate fasteners, pipes/tubes and the like and especially for the operation of plumbing-type fittings.
- the pliers preferably include a locking function.
- the locking function can be used to provide a 'vice grip' type clamping action that can be used for the purpose of gripping or clamping in a locking manner many differing shapes, materials or fasteners.
- gripping mechanism of the invention is not limited to pliers as shown in the embodiments.
- present invention could be advantageously applied to the clamping and locking mechanism of bar clamps used in such fields as carpentry.
Abstract
Description
- The invention relates to hand operated gripping tools and particularly to hand operated gripping tools that are adjustable to any size of workpiece within the range of the jaws of the tool. One form of hand operated gripping tool to which the invention is particularly applicable is pliers of the type generally referred to as water pump pliers or slip joint pliers.
- Existing water pump pliers have the common characteristic of jaws offset at an angle to the pliers handles and a pivot post, in the form of a bolt or rivet, mounted in the area rearward of the jaw on one of the handles and projecting through an elongate slot on the other handle. In such pliers, means for enabling selective spacing of the distance between the jaws may take the form of spaced apart ridges or teeth provided along the inside long edge of the slot and adapted for incremental selective binding engagement with the pivot post. Another well known way of providing distance adjustment between the jaws in such pliers is to provide spaced apart arcuate ridges on the facing surfaces of the slot for engagement by the pivot post. All such tools require a two-handed operation to adjust the jaw spacing the size of a workpiece to be gripped between the jaws. This adjustment involves pulling the handles apart to permit the pivot post to slide along the slot to move the movable one of the jaws to a position that provides a jaw spacing approximating to the size of the workpiece that is to be gripped.
- Other known types of pliers are adapted to slideably close upon a workpiece in response to manual closing of the handles and, in response to contact with the workpiece, automatically lock against further sliding action by engaging suitable teeth and thereby shift from a sliding to a pivoting mode whereby continued exertion of manual force on the handles increases the gripping action upon the workpiece.
- The gripping action of the known pliers is a function of the relationship between the length of the operating handles and the length of the jaws from the pivot post, which is typically in a ratio of around 5:1. The result is that a considerable portion of the torque applied to the operating handles is required to grip the workpiece, meaning there is often insufficient torque available to shift a tight workpiece.
- In certain circumstances it would be a considerable advantage to be able to lock pliers upon a workpiece. The known pliers are unable to include this function.
- Another drawback of the known pliers is that the pivot post fixing action, whether by spaced apart ridges, teeth or arcuate ridges in the slot, is such that the jaws/handles are seldom in an optimum position prior to the shift from sliding to a pivoting mode. This results in a variable gripping action upon the workpiece.
- The invention provides a hand operated gripping tool comprising a first jaw unit having a workpiece engaging portion, a second jaw unit having a workpiece engaging portion and movable relative to said first jaw unit such that a variable size workpiece receiving space is defined between said workpiece engaging portions and a handle for applying a force to said second jaw unit, said second jaw unit being engageable with a reaction surface such that, in use, in response to a said force applied by said handle the workpiece engaging portion thereof is forced against a workpiece received in said workpiece receiving space, at least one of said first and second jaw units comprising a bend promoting portion configured to promote limited bending of the jaw unit in a direction away from the other jaw unit in response to a reaction force generated by engagement with a said workpiece disposed between said first and second jaw units.
- The hand operated gripping tool may comprise a camming device connected with said pivotal handle for causing said second jaw unit to engage said reaction surface.
- The hand operated gripping tool may comprise a fixed handle connected with said first jaw unit and a pivotal link pivotally connected to each said handle and provided with a slide pin that is slideable in a slot defined by one said handle.
- The hand operated gripping may have a locking member that is engageable with said pivotal link for locking said second jaw unit.
- The locking member may be provided with formations for cooperably engaging formations provided on said pivotal link.
- The hand operated gripping tool may comprise a biasing device arranged to bias said locking member to an operative position.
- The invention also includes a hand operated gripping tool comprising a first jaw unit, a second jaw unit, a first cam associated with said first jaw unit, a pivotal handle for applying an operating force to said first jaw unit and a second cam associated with said pivotal handle, said first and second jaw units being cooperable to define a variable size space for receiving a workpiece and said first and second cams being operable in response to a said operating force to cause said first and second jaw units to grip a said workpiece that is positioned in said variable size space, at least one of said first and second jaw units comprising a flexure promoting portion configured to promote flexure of the jaw unit away from said variable size space in response to a reaction force generated by a workpiece gripped between said first and second jaw units in said variable size space.
- The first jaw unit may comprise a connection portion between said first cam and said pivotal handle and said flexure promoting portion may be defined by said connection portion, said flexure promoting portion defining a fulcrum about which said first jaw unit can flex away from said variable size space.
- The second jaw unit may comprise a said flexure promoting portion, said flexure promoting portion comprising a recess provided in an outer side surface of said second jaw unit that faces away from said variable size space
- The invention also includes a hand operated gripping tool comprising first jaw means, second jaw means cooperable with said first jaw means to define an variable size workpiece receiving space, support means on which said first jaw means is slideable for varying the size of said workpiece receiving space and a pivotable lever means, said first jaw means and said pivotable lever means each being provided with engagement means for engaging respective parts on said support means such that pivoting movement of said lever means in one direction causes said first jaw means to move against a workpiece that is positioned in said workpiece receiving space at least substantially in contact with said first and second jaw means so as to grip said workpiece and said first jaw means being configured to permit limited bending movement away from said workpiece receiving space in response to a reaction force generated by a workpiece gripped between said first and second jaw units in said variable size space.
- The engagement means and respective parts on the support means may be arranged such that over a range of said pivoting movement in said one direction said movement generates a progressively increasing gripping force.
- At least one of said engagement means may be arranged to cooperate with the respective said part on said support means such that pivoting movement in said one direction beyond said range of said movement locks said first jaw means in position against a workpiece received in said workpiece receiving space.
- The hand operated gripping tool may comprise automatic locking means for locking said first jaw means independently of engagement between said engagement means and the respective parts on said support means when, in use, said lever means is moved in said one direction beyond a locking position.
- The automatic locking means may be selectively positionable in an inoperative position.
- The first jaw means may comprise corrugation means for permitting said bending movement.
- The corrugation means may comprise at least one arch formed in said first jaw means, said arch arching in the plane of the first jaw means and generally towards said workpiece receiving space.
- In order that the invention may be well understood, some embodiments thereof, which are given by way of example only with reference to the drawings in which:
-
Figure 1 shows a first embodiment of a hand operated gripping tool with certain laminations removed and an automatic locking device of the tool in an operative, but unlocked condition; -
Figure 2 shows the first embodiment with certain laminations removed and the automatic locking device in a locking condition; -
Figure 3 shows the first embodiment with certain laminations removed and the automatic locking device in withdrawn non-operative condition; -
Figure 4 is an enlargement of a portion ofFigure 3 showing a movable jaw unit in greater detail; -
Figure 5 shows a second embodiment of a hand operated gripping tool gripping a fastener-type workpiece with a lamination of a jaw unit removed to reveal internal parts of the tool; -
Figure 6 shows a third embodiment of a hand operated gripping tool in a relaxed open condition loosely holding a fastener-type workpiece with a lamination of a jaw unit removed to reveal internal parts of the tool; -
Figure 7 shows the third embodiment in a locked condition with a top lamination of a link arm removed in order to reveal the internal parts of the tool; -
Figure 8 shows a fourth embodiment of a hand operated gripping tool clamping two plates together and with a link member removed to reveal internal parts of the tool; -
Figure 9 shows a fifth embodiment of a hand operated gripping tool with link member removed in order to reveal internal parts of the tool; -
Figure 10 shows the fifth embodiment partially operated with its jaw units coming against a workpiece; -
Figure 11 shows the fifth embodiment in an other operating position and gripping a different workpiece; -
Figure 12 shows a sixth embodiment of a hand operated gripping tool opened to receive a fastener and with a link member removed to reveal internal parts of the tool; -
Figure 13 is a view of the sixth embodiment corresponding toFigure 13 but showing the tool clamped onto a workpiece; - In the following description of the illustrated embodiments of a hand operated gripping tool, like parts of the tool will be referred to by the same reference numbers.
-
Figures 1 to 4 illustrate a first embodiment of a hand operated gripping tool in the form ofpliers 1. Thepliers 1 comprise afixed jaw unit 2a, amovable jaw unit 2b, afixed handle 3 and apivotal handle 4. Eachjaw unit jaw gripping profiles movable jaw unit 2b can be moved relative to thefixed jaw unit 2a by operation of thepivotal handle 4 to provide a variable size workpiece receiving space between thejaw gripping profiles jaw units fixed handle 3 andpivotal handle 4 can be laminate structures. InFigures 1 to 4 , the uppermost (as viewed in the drawings) laminations have been removed to reveal internal features of thepliers 1. - The fixed
jaw unit 2a is connected with asupport member 3a for themovable jaw 2b. Thesupport member 3a extends transverse to thefixed jaw unit 2a (in this embodiment the jaw support member extends approximately perpendicular to the fixed jaw unit). Themovable jaw unit 2b is able to slide along thesupport member 3a to vary the size of the workpiece receiving space. Thesupport member 3a defines a first clamp, or reaction,surface 3b and a second clamp, orreaction surface 3c. The first andsecond clamp surfaces fixed handle 3 is connected with an end of thesupport member 3a such that the support member extends between and connects thefixed handle 3 to thefixed jaw unit 2a. - The
movable jaw unit 2b is a laminate structure comprising ajaw centre member 2h and an extension portion comprising twoelongate link members 5e. InFigures 1 to 3 , theuppermost link member 5e (as viewed in the drawings) has been removed to reveal internal features of thepliers 1. Themovable jaw unit 2b comprises acam surface 2c, which is defined by thejaw centre member 2h and is engageable with thefirst clamp surface 3b. Thelink members 5e are attached to the sides of ajaw centre member 2h such that the jaw centre member is sandwiched between the link members. The portions of thelink members 5e that are attached against the sides of thejaw centre member 2h are shaped to correspond to the profile of the jaw centre member and so includejaw gripping profiles link members 5e extend from thejaw centre member 2h and are disposed in opposed spaced apart relation to define a gap therebetween. Thesupport member 3a extends through the gap defined between thelink members 5e. Apivotal handle 4 is pivotally connected withmovable jaw unit 2b by means of apivot pin 6 at a connection location adjacent the respective free ends of thelink members 5e. - As best seen in
Figure 4 , thelink members 5e comprise a bend, or flexure, promotingportion 5f. When themovable jaw unit 2b is assembled to thesupport member 3a, thebend promoting portion 5f is disposed between thefirst clamp surface 3b and the connection location at which thepivotable handle 4 is connected to themovable jaw unit 2b by thepivot pin 6. Specifically, in the illustrated embodiment thebend promoting portion 5f extends between thecam surface 2c andsecond clamp surface 3c. - The
bend promoting portion 5f comprises a bowed, or corrugated, section that is bowed in the general direction of the fixedjaw unit 2a. The bowing is in the plane of thelink members 5e. - As best seen in
Figure 1 , thepivotal handle 4 is provided with a toothed pivotal handle cam 4at, which is positioned on the pivotal handle adjacent thepivot pin 6 such that when the pivotal handle pivots on the pivot pin, the cam 4at pivots about the axis of the pivot pin. The teeth of the toothed pivotal handle cam 4at engage atoothed slip shoe 17t that engages and is slideable along thesecond clamp surface 3c. - A
pivotal link 12 extends between the fixedhandle 3 andpivotal handle 4. Thepivotal link 12 is pivotally connected to the fixedhandle 3 by apivot pin 12b that is slideably received in aslot 3e defined in the fixedhandle 3. Theslot 3e extends in the lengthways direction of the fixedhandle 3 and when the uppermost (as viewed in the drawing) lamination of the handle is in place, cannot be seen. Thepivotal link 12 is pivotally connected to thepivotal handle 4 by apivot pin 12a. A biasing member in the form of atension spring 8 is connected to thepivot pin 12a and a location on thepivotal handle 4 and is arranged to bias the pivotal handle to the position shown inFigure 1 . InFigure 1 , the pliers are shown in a fully open condition in which the workpiece receiving space defined between thejaw units - The
pliers 1 are provided with an automatic locking device that comprisesteeth 22 provided on the end of thepivotal link 12 adjacent thepivot pin 12a and a lockingmember 24. The lockingmember 24 is pivotally mounted on thepivotal handle 4 on apivot pin 26. Thepivot pin 26 is fixed to thepivotal handle 4 and extends through a lengthways extending slot 27 (Figure 2 ) provided in the lockingmember 24. The lockingmember 24 has athumb tab 28 for actuation by a user of thepliers 1. When the uppermost lamination of thepivotal handle 4 is in place, thethumb tab 28 is the only portion of the lockingmember 24 that is visible. - Referring particularly to
Figures 2 and4 , at the end of the lockingmember 24 opposite thethumb tab 28, the side of the member facing away from thepivotal handle pin 6 is provided withteeth 30 for engaging theteeth 22 on thepivotal link 12. On the other side of the lockingmember 24 opposite theteeth 30, there is a recess that houses an end of a resilient member, which in this embodiment iscompression spring 32. The opposite end ofcompression spring 32 is held in arecess 34 provided in thepivotal handle 4. As best seen inFigure 4 , the toothed end of the lockingmember 24 is provided with a nose-like projection 36 that engages inrecesses pivotal handle 4 to locate the lockingmember 24 in its inoperative and operative positions respectively. Thecompression spring 32 biases the lockingmember 24 to the operative position shown inFigures 1 and2 in which theprojection 36 engages in therecess 40 and the member is able to automatically engage theteeth 22 provided on the end of thepivotal link 12. When theprojection 36 is engaged in therecess 38, the locking member is held in a withdrawn position in which it cannot engage with thepivotal link 12. Thus, the lockingmember 24 can be locked in a withdrawn inoperative position. This means that when desired thepliers 1 can be used without the automatic locking device. When a user wishes to activate the automatic locking device, thethumb tab 28 is used to slide the lockingmember 24 outwardly with respect to thepivotal handle 4 to withdraw theprojection 36 from therecess 38. Once theprojection 36 is clear of therecess 38, thecompression spring 32 acts against the toothed end of the locking member to move the locking member to the operative position shown inFigures 1 and2 in which it is ready to automatically engage thepivotal link 12. - In
Figure 2 , theteeth 30 on the lockingmember 24 are shown engaging theteeth 22 on thepivotal link 12, thereby locking thejaw units teeth pivotal link 12 pivots from the position shown inFigure 1 to the position shown inFigure 2 , they automatically engage in the manner of a ratchet. The biasing force provided by thecompression spring 32 presses theteeth 30 into theteeth 22, thereby ensuring that locking engagement is maintained. - The lock can be released by pushing down (as viewed in
Figure 2 ) on thethumb tab 28 to cause the toothed end of the lockingmember 24 to pivot clockwise to release thepivotal link 12 and allow free movement of thepivotal handle 4 relative to the fixedhandle 3. When thethumb tab 28 is released, the toothed end of the lockingmember 24 is returned to the position shown inFigure 1 so that the locking member is ready to automatically engage theteeth 22 of thepivotal link 12. - The bend or
flexure promoting portion 5f has been found to provide advantages in the operation of thepliers 1. It will be appreciated that when themovable jaw unit 2b engages a workpiece trapped between thejaw gripping profiles teeth 22 on thepivotal link 12 fully engage theteeth 30 on the lockingmember 24. This is particularly so if thejaw units teeth movable jaw unit 2b away from the workpiece, as additional force is applied to thepivotal handle 4 by the user, sufficient additional movement of the handle is available to ensure full engagement of theteeth - Referring to
Figure 4 , an optional recess, or cut-out, 2m is shown provided in the fixedjaw unit 2a. This allows additional flexure of thejaw units jaw units - It will be appreciated that the configuration of the
bend promoting portion 5f and, when provided, therecess 2m can be varied considerably to provide the degree of flexure required. For example, the bend promoting portion of 5f comprises a single bow or arch directed in the general direction of the workpiece receiving space. It is envisaged that further arches, undulations or corrugations in the plane of thelink members 5e could by provided. It will also be appreciated that the degree of allowed bending should be relatively small, otherwise, thepliers 1 will not be able to provide a satisfactory gripping action. The degree of flexure required and allowable for satisfactory operation on thepliers 1 can readily be determined by experiment. - Optionally, the first and
second clamp surfaces support member 3a are not parallel. Instead, thefirst clamp surface 3b tapers towards thesecond clamp surface 3c as the two surfaces approach the fixedjaw 2a. This tapering of thesupport member 3a is shown inFigure 4 . The wedge effect this provides causes the movablejaw unit cam 2c to act more quickly and to lock better. This also allows the jaw angle to be less likely to result in a partial closure when gripping a thin workpiece as the thinning of thesupport member 3a towards the fixedjaw unit 2a can cancel out the effect of any rotation of the toothed pivotal handle cam 4at against thetoothed shoe 17. -
Figure 5 illustrates a second embodiment of a hand operated gripping tool in the form ofpliers 1. Thepliers 1 are shown in a closed condition gripping a fastener-type workpiece between thejaw units link member 5e has been omitted to reveal internal parts of thepliers 1. - In the second embodiment, the
support member 3a extends generally perpendicular to thefirst jaw unit 2a and has first andsecond clamp surfaces slot 3d extends in the lengthways direction of thesupport member 3a. Aslide pin 7 extends through theslot 3d generally perpendicular to the plane of thesupport member 3a and is held in respective bushes provided in thelink members 5e. Theslide pin 7 is able to slide along theslot 3d as thesecond jaw unit 2b slides along thesupport member 3a. A resilient member in the form of atension spring 8 is housed within theslot 3d. One end of thespring 8 is secured to the fixedjaw 2a by aspring post 9. The opposite end of theresilient member 8 is secured to theslide pin 7. Thespring 8 pulls thesecond jaw unit 2b towards thefirst jaw unit 2a such that thatpliers 1 are biased towards a closed condition and will provide a light clamping force on theworkpiece 11a prior the application a force F to thepivotal handle 4. - The
pivotal handle 4 is provided with anintegral cam 4a that acts against thesecond clamp surface 3c of thesupport member 3a to cause rotation of thecam 2c of thesecond jaw unit 2b against thefirst clamp surface 3b. Thepivotal arm 4 is also provided with respective stop surfaces 4d arranged to be engageable with stops 5d that project from thelink members 5e and serve to limit movement of thepivotal handle 4 away from the fixedhandle 3. - There now follows a description of five further embodiments of a hand operated gripping tool in the form of
pliers 1 that in each case comprise a bend, or flexure, promoting feature in one or both of the two jaw units. These embodiments show how the flexure promoting concept can be incorporated into various configurations of hand operated gripping tool and the description of them will provide further illustration of the functioning of the first embodiment. -
Figures 5 and6 shows a third embodiment of a hand operated gripping tool in the form ofpliers 1 with the uppermost (as viewed in the drawing)link arm 5e removed in order to show internal parts of the tool. - In
Figure 4 , thepivotal handle 4 is shown in a fully opened position. In this position thecam 4a on thepivotal handle 4 has been moved out of engagement with theslip shoe 17 and thecam surface 2c is spaced from thefirst clamp surface 3b (see the gap Ga). In this condition of thepliers 1, it is only necessary to overcome the tension of theresilient member 8 in order to rotate thejaw units jaw gripping profiles workpiece 11a. - The
slip shoe 17 is shown to be in the form of a cross. Theslip shoe 17 is held between thecam 4a on thepivotal handle 4 and thesecond clamp surface 3c by the arms 17a of the slip shoe engaging in respective slots (not shown) in thelink members 5e. Theslip shoe 17 is thus constrained to move with themovable jaw unit 2b as it slides on thesupport member 3a. - The cam-to-cam distance D2 between the
cams -
Figure 7 shows the third embodiment with the pivotal handle in the fully closed position and thejaws units workpiece 11c in the form of two plate-like members. The movement of thepivotal handle 4 to the fully closed position has rotated thecam 4a past the slip shoe to bring alocking surface 4b has into firm contact with thesecond clamp surface 3c via theslip shoe 17. The operation of theclamp 4a on the pivotal handle has moved themovable jaw unit 2b on thecam surface 2c to bring alocking portion 2d of themovable jaw unit 2b into engagement with thefirst clamp surface 3b above the centre of the pivot pin 6 a distance D1. This arrangement prevents thepivotal handle 4 from moving outwards with respect to the fixedhandle 3 unless manually moved in that way. This locks thepliers 1 in the closed position gripping theworkpiece 11c. -
Figure 8 is a plan view of the fourth embodiment of a hand operated gripping tool in the form ofpliers 1. Again, an uppermost (as viewed in the drawing)link member 5e of themovable jaw unit 2b has been omitted to show internal features of thepliers 1. - In this embodiment the fixed
handle 3 is joined directly to the fixedjaw unit 2a. Theresilient member 8 is not within an elongate slot in thesupport arm 3a. Instead, it is held betweenrespective spring posts 9 fitted to the fixedjaw unit 2a andmovable jaw unit 2b. Theresilient member 8 is arranged to bias themovable jaw unit 2b towards the fixedjaw unit 2a and position thecam 4a on thepivotal handle 4 against thesecond clamp surface 3c when thepliers 1 is in a rest position. In this embodiment, there is no slip shoe, so thecam 4a bears directly against thesecond clamp surface 3c. - In
Figure 8 , thepivotal handle 4 is shown moved fully towards the fixedhandle 3, resulting in a lockingportion 4b of thepivotal handle 4 being brought into full contact with thesecond clamp surface 3c so that thejaw units workpiece 11c. -
Figures 9 to 11 show a fifth embodiment of a hand operated gripping tool in the form ofpliers 1. InFigures 10 and11 the fixedhandle top laminate 3g, pivotalhandle top laminate 4e andtop link member 5e are shown removed. - In
Figure 9 thepliers 1 are shown at rest. Theresilient member 8 is acting on thepivotal handle 4 andpivotal link 12 to urge themovable jaw unit 4b down thesupport member 3a away from the fixedjaw unit 2a. This moves thecam surface 2c off thefirst clamp surface 3b to open a gap Ga. Astop 4d on thepivotal handle 4 acts against a stop 5d on thelink member 5e to limit the movement of the pivotal handle. Thecam 4a on thepivotal handle 4 is off of thesecond clamp surface 3c. - In
Figure 10 thepivotal handle 4 is shown pushed towards the fixedhandle 3 by a force F that causes it to pivot around thepivotal link 12 against the resistance of theresilient member 8 until the movement is arrested by thejaw units workpiece 11a. During this part of the movement the initial engagement of thecam 4a on thepivotal handle 4 with thesecond clamp surface 3c causes no effective clamping action on thefastener 11a. - In
Figure 11 thepivotal handle 4 and pivotal links are shown in a fully operated position causing thejaw units tubular workpiece 11b. The force F applied to thepivotal handle 4 has caused thepivot pin 12b to travel down theslot 3e in the fixedhandle 3, thereby extending theresilient member 8. This allows thepivotal handle 4 to rotate around thepivot pin 6 causing thecam 4a on the pivotal handle to act on thesecond clamp surface 3c. This action rotates themovable jaw unit 2b on thecam surface 2c driving the lockingportion 2d towards thefirst clamp surface 3b further improving the gripping action of thejaw units workpiece 11b. This allows considerable torque to be applied to the rotation of theworkpiece 11b, whilst a reduced force F is required to ensure thejaw units workpiece 11b. -
Figures 12 and 13 illustrate a sixth embodiment of a hand operated gripping tool in the form ofpliers 1. The uppermost (as viewed in the drawings)link member 5e is shown removed to reveal internal parts of thepliers 1. In this embodiment, there is nofixed handle 3. - As illustrated in
Figure 12 thejaw units support member 3a to move the fixed jaw unit away from themovable jaw unit 2b. The axial force F acts against the biasing force of theresilient member 8, which is held betweenrespective spring posts 9 fixed to thejaw units resilient member 8 pulls thejaw units workpiece 11a between the jaw units. - Referring to
Figure 13 , a force F applies a torque to thepivotal handle 4 to cause thecam 4a on the pivotal handle to act on thesecond clamp surface 3c via aslip shoe 17. This causes themovable jaw unit 2b to pivot on thecam surface 2c to provide a firm grip on theworkpiece 11 a. - The embodiments shown in
Figures 5 to 8 have a fixedjaw unit 2a that is attached to a fixedhandle 3 via anelongate support member 3a and amovable jaw unit 2b that is attached via one ormore link members 5e to apivotal handle 4 such that it can slide and pivot relative to the fixedjaw 2a. Thesupport member 3a is an elongate bar with parallel oppositely facingclamp surfaces Figure 4 , the support member may taper towards the fixed jaw unit. With thepivotal handle 4 in the open position, themovable jaw unit 2 bandpivotal handle 4 are free to slide to and fro along thesupport member 3a. There is be anelongate slot 3d within thesupport member 3a containing a resilient member in the form of anextension spring 8 that has one end attached to themovable jaw unit 2b by aslide pin 7 and the other end attached to the fixedjaw unit 2a by a spring post 9 a. Theextension spring 8 acts to urge the twojaw units jaw units pivotal handle 4 is manually moved away from the fixedhandle 3 and propelled along theelongate bar 3a to allow a workpiece 11 to enter between thejaw units pivotal handle 4 allows thespring 8 to close thejaw units pivotal handle 4 towards the fixedhandle 3 then brings thecam 4a on the pivotal handle into contact with thesecond clamp surface 3c on thesupport member 3a to cause themovable jaw 2b to pivot on thecam surface 2c of themovable jaw unit 2b against thefirst clamp surface 3b. Thepivotal handle 4 has acam locking portion 2d that can be moved into engagement with thesupport member 3a at a location positioned above thecam surface 2c (ie nearer to the fixedjaw unit 2a). The grip between thejaw units cam 4a is rotated against thesecond clamp surface 3c causing themovable jaw unit 2b to rotate towards the fixed jaw unit until the lockingportion 2d comes into contact with thefirst clamp surface 3b. Providing thecam 4a on thepivotal handle 4 is suitably proportioned and has sufficient force exerted upon it by the actuation of thepivotal handle 4 towards the fixedhandle 3, the workpiece 11 will be firmly clamped between thejaw units movable jaw 2b rotation on thecam surface 2c until the lockingportion 2d is clamped against thefirst clamp surface 3b. In use, this can result in additional force being exerted outwardly upon thejaw units movable jaw unit 2b,cam surface 2c, lockingportion 2d,cam 4a and the lockingportion 4b and will correspondingly increase the clamping action upon the clamp surfaces 3b, 3c of thesupport member 3a. Givenappropriate handle jaw unit cam - The
pliers 1 can be manually operated by the operation of thepivotal handle 4 only. The grip on the workpiece 11 can be increased by manually increasing the force F applied between the pivotal andfixed handles jaw units extension spring 8. This makes it possible to reposition the pliers on the workpiece in a manner similar to a ratchet wrench. - A further locking function can be incorporated in the
pliers 1 by the provision of a generally flat locking portion orportions 4b adjacent to thecam 4a on thepivotal handle 4 such that movement of thecam 4a past thesecond clamp surface 3c brings the locking portion orportions 4b into engagement with the clamping surface. Providing the lockingportion 4b engages thesecond clamp surface 3c past a point equivalent to a right angle from theclamp surface 3c through the centre point of the pivot pin 6 (the cam lock distance D1), thejaw units pivotal handle 4 is manually operated away from the fixedhandle 3. - In some embodiments, in order to minimise the overall size of the
pliers 1, the layout of thehandles cam 4a on thepivotal handle 4 acting upon theouter clamp surface 3c possibly causing thejaw units slip shoe 17 can be provided. Theslip shoe 17 can be retained within apertures in thelink members 5e to ensure it is correctly positioned between thecam 4a and thesecond clamp surface 3c. In use thecam 4a then slips on the smooth surface of theslip shoe 17. - The embodiment shown in
Figures 9 to 11 incorporates apivotal link 12 between the fixed andmovable handles resilient member 8 pulls thepivotal link 12 to a position in which its movable end and the associatedpivot pin 12a are at the end of theslot 3e in the fixed handle that is closest to the jaw units. This holds the jaws in the open position shown inFigure 9 . Initial operation of thehandles Figure 9 results in thepivotal handle 4 pivoting around the pivot link andpivot pin 12a, rapidly closing thejaw units jaw units pivotal handle 4 forces the movable end of thepivotal link 12 and the associatedpivot pin 12b along theslot 3e against the return force generated in theresilient member 8. This allows thepivotal handle 4 to rotate further towards the fixedhandle 3. Moving thepivotal handle 4 towards the fixedhandle 3 causes thecam 4a to act on thesecond clamp surface 3c. Themovable jaw unit 2b then pivots on thecam surface 2c, further closing thejaw units - As shown in
Figures 12 and 13 , a fixedhandle 3 is not necessarily required, provided theresilient member 8 is strong enough to ensure closure of thejaw units pivotal handle 4 until thecam 4a has sufficient grip on thesecond clamp surface 3c to allowmovable jaw unit 2b to pivot on thecam surface 2c.. - The geometrical proportions of the
pliers 1 can be varied to suit many different applications and gripping forces. - It will be appreciated that convention hand operated gripping tools are designed to rigid and strong and, in particular, the jaw units are not designed to flex away from the workpiece. By providing a designed weakening of one or both jaw units that actually promotes a limited bending away from the workpiece, and so away from the other jaw unit, it is possible to ensure that a locking function of the tool fully engages, even when the tool is being clamped onto a hard rigid workpiece. Thus a reliable clamping action can be achieved.
- It will be appreciated that the or each jaw unit that is provided with a bend promoting portion should be made of a material (typically a steel) that is sufficiently resilient to cope with the bending without being permanently deformed or otherwise damaged by it.
- Embodiments of the invention include a set of pliers for applying a torque to rotate fasteners, pipes/tubes and the like and especially for the operation of plumbing-type fittings. The pliers preferably include a locking function. Preferably, the locking function can be used to provide a 'vice grip' type clamping action that can be used for the purpose of gripping or clamping in a locking manner many differing shapes, materials or fasteners.
- It will be appreciated that the gripping mechanism of the invention is not limited to pliers as shown in the embodiments. For example the present invention could be advantageously applied to the clamping and locking mechanism of bar clamps used in such fields as carpentry.
Claims (15)
- A hand operated gripping tool comprising a first jaw unit having a workpiece engaging portion, a second jaw unit having a workpiece engaging portion and movable relative to said first jaw unit such that a variable size workpiece receiving space is defined between said workpiece engaging portions and a handle for applying a force to said second jaw unit, said second jaw unit being engageable with a reaction surface such that, in use, in response to a said force applied by said handle the workpiece engaging portion thereof is forced against a workpiece received in said workpiece receiving space, at least one of said first and second jaw units comprising a bend promoting portion configured to promote limited bending of the jaw unit in a direction away from the other jaw unit in response to a reaction force generated by engagement with a said workpiece disposed between said first and second jaw units.
- A hand operated gripping tool as claimed in claim 1, wherein said second jaw unit comprises an elongate extension portion extending from said workpiece engaging portion, said lever arm being connected with said elongate extension portion at a connection location and said extension portion having a said bend promoting portion disposed between said workpiece engaging portion and said connection location.
- A hand operated gripping tool as claimed in claim 2, wherein said bend promoting portion comprises a section that is bowed transverse to a lengthways direction of the extension portion.
- A hand operated gripping tool as claimed in claim 3, wherein said extension portion comprises at least one planar member and said bowed section is bowed in a plane of the extension portion.
- A hand operated gripping tool as claimed in claim 3 or 4, wherein said bowed section arches generally towards said first jaw unit.
- A hand operated gripping tool as claimed in any one of claims 2 to 5, wherein said extension portion comprises two elongate members disposed in opposed spaced apart relation, each said elongate member comprising a said bend promoting portion.
- A hand operated gripping tool as claimed in any one of the preceding claims, wherein said second jaw unit has a said bend promoting portion and said bend promoting portion is disposed adjacent said reaction surface.
- A hand operated gripping tool as claimed in any one of the preceding claims, comprising a support member for said second jaw unit, said support member extending transversely with respect to said first jaw unit and said second jaw unit being slideable with respect to said first jaw unit on said support member for varying the size of said workpiece receiving space.
- A hand operated gripping tool as claimed in claim 8, wherein said support member defines said reaction surface.
- A hand operated gripping tool as claimed in claim 8 or 9, wherein said support member includes a first side surface facing into said workpiece receiving space and a second side surface disposed opposite and spaced from said first side surface, the spacing between said first and second side surfaces decreasing as said first and second side surfaces approach said first jaw unit.
- A hand operated gripping tool as claimed in any one of the preceding claims, comprising an locking device for locking said second jaw unit to fix the size of said workpiece receiving space, said locking device comprising a locking member movable to a withdrawn non-operative position.
- A hand operated gripping tool as claimed in claim 11, wherein said locking device is moveable between an operative position in which it provides an automatic locking action and a withdrawn position in which it is inoperative.
- A hand operated gripping tool as claimed in any one of the preceding claims, wherein said first jaw unit comprises a said bend promoting portion, said bend promoting portion comprising a recess provided in an outer side surface of said first jaw unit that faces away from said workpiece receiving space.
- A hand operated gripping tool as claimed in claim 1, wherein said second jaw unit comprises corrugations for permitting said limiting bending movement.
- A hand operated gripping tool as claimed in claim 1, wherein said bend promoting portion is disposed between said workpiece engaging portion of the second jaw unit and a location at which a force is applied to said second jaw unit by said handle, said bend promoting portion defining a fulcrum.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0721292A GB0721292D0 (en) | 2007-10-30 | 2007-10-30 | Hand operated gripping tool |
Publications (1)
Publication Number | Publication Date |
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EP2055431A1 true EP2055431A1 (en) | 2009-05-06 |
Family
ID=38834529
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP08167998A Withdrawn EP2055431A1 (en) | 2007-10-30 | 2008-10-30 | Hand Operated Gripping Tool |
Country Status (3)
Country | Link |
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EP (1) | EP2055431A1 (en) |
GB (1) | GB0721292D0 (en) |
RU (1) | RU2484942C2 (en) |
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Publication number | Priority date | Publication date | Assignee | Title |
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CA2877806C (en) * | 2012-07-10 | 2020-07-07 | Gustav Klauke Gmbh | Pressing tool |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2072081A (en) * | 1980-03-19 | 1981-09-30 | Toolema Ab | Tool having two working jaws particularly for use in crimping |
DE29816558U1 (en) * | 1997-11-27 | 1998-12-10 | Wang Kuang Pin | Pliers |
WO2007099349A2 (en) * | 2006-03-03 | 2007-09-07 | Buchanan, Nigel, Alexander | Hand operated gripping tool |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SU1315284A1 (en) * | 1986-01-24 | 1987-06-07 | Б.Н.Балашев, А.Я.оглы Ахмед-заде, Г. В. Валенцев, В.П.Лукин и А.И.Шаповал | Hand tool |
WO2000013856A1 (en) * | 1998-09-07 | 2000-03-16 | Knipex-Werk C. Gustav Putsch | One-hand actuated, self-closing pliers |
TW547267U (en) * | 2002-12-03 | 2003-08-11 | Wang Bang Jung | Locking pincer with sheath |
-
2007
- 2007-10-30 GB GB0721292A patent/GB0721292D0/en not_active Ceased
-
2008
- 2008-10-30 EP EP08167998A patent/EP2055431A1/en not_active Withdrawn
- 2008-10-30 RU RU2008143059/02A patent/RU2484942C2/en not_active IP Right Cessation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2072081A (en) * | 1980-03-19 | 1981-09-30 | Toolema Ab | Tool having two working jaws particularly for use in crimping |
DE29816558U1 (en) * | 1997-11-27 | 1998-12-10 | Wang Kuang Pin | Pliers |
WO2007099349A2 (en) * | 2006-03-03 | 2007-09-07 | Buchanan, Nigel, Alexander | Hand operated gripping tool |
Also Published As
Publication number | Publication date |
---|---|
RU2008143059A (en) | 2010-05-10 |
GB0721292D0 (en) | 2007-12-12 |
RU2484942C2 (en) | 2013-06-20 |
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