FIELD OF THE INVENTION

This invention relates to clamping and adjustable holding devices such as vices, sash-cramps and the like, and relates particularly to a clamping device for clamping a work piece such as is commonly used for wood-working tasks.

While the clamping device of this invention may be used in any position relative to the horizontal and vertical planes, it will be convenient for the purpose of description to assume that it is disposed so that the jaw movement is in the horizontal plane. No restriction with regard to the device is implied by the use of this convention.

BACKGROUND TO THE INVENTION

Many forms of sash-cramps and vices are known but, in general, sash cramps are portable devices that allow large flat articles to be clamped with moderate force while vices are fixed devices designed to clamp smaller articles more tightly. Sash cramps normally comprise a pair of bolsters slidably mounted on a long bar or rail, at least one of the bolsters having a jack-screw mounted therein. In operation, the bolsters are slid apart along the bar until the article co be clamped can fit there-between then, after the bolsters are fixed to the bar by pins or other means, the jack-screw is operated to exert the desired clamping pressure. The common vice, of course, comprises a combined fixed jaw and body adapted to be bolted to a work-bench and a moving jaw that slides within the fixed jaw, the moving jaw being moved by means of a jack-screw which, again, is used to apply the holding force on a work-piece held between the jaws. A problem common to both sash-cramps and vices is that it is difficult to accurately position a work piece within the device while the jack-screw is tightened, and this is a particular problem with sash-cramps which are not themselves fixed to work-benches. Furthermore, the spacing of the bolsters of many sash-cramps can only be adjusted in

relatively large increments so that it is often necessary to turn the jack-screw for some distance while holding the work in place before the clamping force is applied. On the other hand, vices cannot open sufficiently to accommodate the needs of most wood-working tasks.

Some of these difficulties are addressed by the foot-operated clamping device disclosed in Australian patent No. 653996 by Triton Technologies Pty Ltd. In this device, the moving jaw slides on a beam supported by a tripod frame, it being possible to bring the moving jaw against the work by sliding it along the beam directly by hand, and then clinching it against the work operation of a foot pedal which, upon actuation, brings a pawl into contact with a rack on the underside of the moving jaw to move that jaw forwards by a small distance. While such a device allows quick adjustment of the moving jaw over a much larger distance than in the case of a vice, serving as a sash-cramp for relatively small work pieces. In effect, this type of device serves as a dedicated sawing horse with a built-in vice for holding logs or beams of wood. It's versatility is severely limited. Furthermore the arrangement of the foot pedal and lever arrangement restricts the orientation of the jaws to a substantially horizontal plane.

SUMMARY OF THE INVENTION The present invention was developed with a view to providing a clamping device that can accommodate small or large work pieces and which, preferably, does not require a dedicated bench for the purpose.

The present invention is based upon the realisation that one or more clamping jaws can be slidably mounted on base member so that they can be easily brought into contact with the work-piece and locked in position, whereupon the necessary clamping force can be applied to the work-piece via an actuator or clinching mechanism c----ried by at least one of the jaws.

According to the present: invention there is

provided a clamping device for clamping a work-piece, the device comprising: a support structure including an elongate base member having a first jaw mounted at one end; a slide member adapted to slidably move along said base member in a non-locking condition, and having a second jaw mounted thereon, wherein said second jaw can be brought into engagement with a work-piece placed between the first and second jaws by sliding the slide member in the non- locking condition towards the first jaw; a releasable locking means for preventing sliding movement of said slide member relative to the base member, whereby said slide member remains locked in a stationary position relative to the base member in a locking condition; and, an actuating mechanism provided in connection with at least one of said first and second jaws for moving said at least one jaw towards the other jaw so as to apply a clamping pressure to the work-piece when the slide member is in the locking position.

Preferably said locking means comprises a locking surface provided in connection with said base member and extending lengthwise of said base member, and wherein said slide member is provided with engaging means adapted to engage with said locking surface in the locking condition. Typically said engaging means and the serrations of said locking surface both comprise ratchet-like teeth, and wherein the teeth on the slide member are normally biased into engagement with the teeth of the serrated surface to manually keep the slide member in the locking condition.

Preferably said teeth on the slide member are normally biased into engagement with the teeth of the serrated surface by the force of gravity acting on the mass of the slide member, and wherein means are provided for manually lifting the slide member so that tht teeth can Xe disengaged.

Advantageously said slide member is formed with at

least one arm that extends forwards of the second jaw parallel to said base member and wherein said teeth on the slide member are located at the free end of said at least one arm, said second jaw being located on the slide member intermediate said free end of the at least one arm and the rear end of the slide member near a pivot point of the slide member, whereby when the slide member is pivoted at the pivot point by lifting the rear end of the slide member said teeth on the at least one arm disengage with the teeth of the serrated surface so as to release the slide member to a non¬ locking condition.

The actuating mechanism may take many different forms. It may be a mechanical cam, toggle or eccentric mechanism (incorporated, at least partially, in one of the jaws) ; it may be a pneumatic or hydraulic device; or it may be a motor-driven device. Where one fixed jaw and one moving jaw are used (as will be common) it will be generally convenient to associate the actuating mechanism with the fixed jaw, though it is envisaged that actuating mechanisms can be used on both jaws or on the moving jaw only.

A force indicator or regulator may be associated with the actuating mechanism. A force indicator is of value in indicating the amount of clamping force applied to a work ^¬ piece, while the regulator would ensure that the desired amount of force was always applied. Such indicators or regulars are of value where, as envisaged above, the jaws can be moved toward one another in small fixed increments by hand before the clinching mechanism is activated. A simple pressure regulator for a mechanical actuating drive using an eccentric or cam may be a constant-force spring.

The base member of the clamping device may also take many different forms. It may comprise part of a work¬ bench or it may be secured to its own frame. In the latter case, it is envisaged that the base member may be pivotally or slidably mounted on the frame so that the work-piece can be arranged in many different positions. The base member may be pivoted about a longitudinal horizontal axis, a transverse

horizontal axis, about a vertical axis and/or about any other convenient axis simply by arranging to support the base member from the frame with suitable trunnions or bearings.

BRIEF DESCRIPTION OF THE DRAWINGS Having broadly portrayed the nature of the present invention, particular embodiments of the clamping device will now be described by way of example and illustration only. In the following description, reference will be made to the accompanying drawings in which: Figure 1 is a general perspective view of a preferred embodiment of the clamping device;

Figure 2 is a part section view through the clamping device of Figure 1,-

Figure 3A is similar to Figure 2 and illustrates the slide member in a locking condition;

Figure 3B is similar to Figure 3A and illustrates the slide member in a non-locking condition;

Figure 3C is a side view of the slide member shown in figures 3A and 3B; Figure 4 is a plan view of one embodiment of an actuating mechanism for the clamping device;

Figure 5 is a similar view to that of Figure 2 but depicts an alternative embodiment of the clamping device;

Figure 6 illustrates a bench-mounted configuration of the clamping device;

Figure 7A and 7B illustrate a third embodiment of the clamping device showing how the jaws can be pivoted about a longitudinal axis;

Figure 8 illustrates the embodiment of Figure 7 showing the extent to which the jaws can be opened; and

Figures 9A and 9B are, respectively, a side elevation and a plan view of one of the jaws of the device showing one form of actuating mechanism which may be employed, together with an alternative jaw locking system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A first embodiment of a clamping device in accordance with the present invention, as illustrated in Figures 1 to 4, has a support structure 10 including an elongate base member 12 having a first jaw 14 mounted at one end. In this embodiment, the first jaw is fixed to the base member however in other embodiments it may be moveable. The base member 12 is made of roll-formed or pressed sheet-metal having two longitudinal ribs 16 joined by a central web 18 as can be seen most clearly in Figure 2. A slide member 20 is adapted to slidably move along the base member 12 in a non¬ locking condition and has a second jaw 22 mounted thereon. The second jaw 22 can be brought into engagement with a work piece (not illustrated) placed between the first and second jaws 14, 22 by sliding the slide member 20 in a non-locking condition towards the first jaw 14.

In this embodiment, a carrier member 24 is interposed between the slide member 20 and the base member 12, however this is by no means essential to the operation of the clamping device. If desired, the slide member 20 may be adapted to slide directly on the upper surface of the base member 12. As can be seen in Figure 2, the carrier member 24 is of similar cross sectional shape as the base member 12. The function of the carrier member 24 will be described in more detail below.

The clamping device further comprises a releasable locking means 26 for preventing sliding movements of the slide member 20 relative to the base member 12 so that the slide member 12 remains locked in a stationary position when placed in a locking condition. The clamping device further comprises an actuating mechanism 28, in this embodiment provided in connection with the second jaw 22 for moving the second jaw towards the first jaw so as to apply a clamping pressure to a work piece (not illustrated) when the slide member 20 is in the locking condition. In Figure 1 the actuating mechanism 28 is concealed below a cover plate, however one form of actuating mechanism is illustrated in

plan view in Figure 4.

The actuating mechanism 28 of Figure 4 includes an electric motor 30 which drives first and second threaded spindles 32 rotatably coupled to the second jaw 22. The motor 30 drives the spindles 32 via a gear transmission which includes a gearbox 34, a central drive gear at 35 and first and second gears 36 mounted on thrust bearings 38, all mounted on the slide member 20. Gears 36 are provided with a threaded central bore through which the spindles 32 pass so that rotation of the gears 36 is converted to an axial displacement of the spindles 32 via the threads on the spindles 32. Guides 40 are also provided in connection with the jaw 22 to accommodate any lateral loading of the jaw 22. The pitch of the threads on the spindles 32 and the gear ratio of the gear transmission is selected so that a relatively high clamping pressure is generated at the jaw 22 from a low torque produced by the motor 30. Electric motor 30 may be battery operated, for example, using rechargeable batteries also mounted on the slide member 20 (not illustrated) . Recharging may be by solar power. A manually operated switch 42 is provided on the cover of the slide member 22 for switching on the motor 30 in a forwards or reverse direction when it is desired to apply or release the clamping pressure respectively. In this way, up to one tonne of clamping pressure can be generated between the first and second jaws 14, 22 using a small 6 volt DC electric motor.

In an alternative arrangement (not illustrated) a foot switch may be provided for controlling the operation of the actuating mechanism 28 in a hands-free mode. The actuating mechanism 28 has been omitted from Figures 2 and 3 for clarity.

As can be seen most clearly in Figure 3A carrier member 24 is provided with first and second locking surfaces 44 on respective downwardly-projecting peripheral edges which lie adjacent the rib 16 of the base member 12. Slide member 20 is provided with first and second arms 46 which extend forwardly of the jaw 22 adjacent the locking surfaces 44 on

the peripheral edges of the carrier member 24. Each arm 46 is provided with engaging means in the form of a segment of ratchet-like teeth at the free end thereof for engaging with the respective locking surfaces 44 on the carrier member 24 in the locking condition of the slide member 20. The locking surfaces 44 are in the form of serrations or ratchet-like teeth which extend along substantially the full length of the carrier member 24. The segment of teeth 48 on the arms 46 of the slide member 20 are normally biased into engagement with the teeth of the locking surfaces 44 by the force of gravity acting on the mass of the slide member 20 to place the slide member 20 in the locking condition as shown in Figure 3A.

In order to release the slide member 20 from the locking condition, the slide member is pivoted at a pivot point 50 by lifting the rear end of the slide member 20 as shown in Figure 3B so that the teeth 48 on the arms 46 disengage with the teeth of the locking surfaces 44 to place the slide member 20 in a non-locking condition. In this condition the slide member 20 may be freely slid backwards or forwards along the carrier member 24 so as to place the second jaw 22 in a desired position relative to the first jaw 14. In this way, the locking means 26 operates to allow fine incremental movement of the second jaw 22 towards the first jaw 14 by direct manual operation. Thus, when a work piece is positioned between the jaws, it is possible to easily move the second jaw 22 along the carrier member 24, (and hence along the base member 12), until the second jaw 22 contacts the work piece. In this position the slide member 20 may be returned to the locking condition before the actuating mechanism is activated to apply the desired clamping pressure. The actuating mechanism 28 is thus required to move the jaw no more than the small distance between adjacent teeth of the locking means 26. Thus a work piece can be quickly clamped in position in the clamping device without any time-consuming or laboi ious intermediate steps as in prior art vices and sash-cramps and the like.

Carrier member 24 is itself provided with a second

releasable locking means for preventing sliding movement of the carrier member 24 relative to the base member 12. As can be seen most clearly in Figure 2, the second releasable locking means comprises first and second detents 52 provided on an inner surface of the carry member adjacent the peripheral edge on which the locking surface 44 is provided. The detents 52 are adapted to engage with a pair of lugs 54 provided on an external surface of the ribs 16 of the base member 12. The carrier member 24 is placed in the locking condition by sliding it along the base member 12 until the detents 52 engage with the lugs 54. A plurality of lugs may be provided at spaced intervals along the length of the base member 12 to allow the carrier member 24 to be placed in the locking condition at selected positions along the length of the base member 12. In this way, carrier member 24 can be used to extend the effective length of the base member 12 so as to increase the maximum gap that can be achieved between the first and second jaw 14, 22. The carry member 24 is shown in an extended position in Figure 1. In the embodiment of Figure 1, the support structure 10 includes an adjustable attachment means 60 for pivotally attaching the base member 12 to a stand 62. The base member 12 can thus be pivoted on a longitudinal axis to a desired angular orientation to enable a work piece to be received between the jaws at any desired angle. This is possible because all of the moving parts of the clamping device are located above the base member 12 where they do not interfere with the free pivoting movement of the base member 12 through 90° in either direction from the horizontal orientation shown in Figure 1. The stand of the illustrated embodiment comprises a first pair of legs 62 provided at one end of the base member and a third leg 64 provided at the other end of the base member 12. Each of the legs has a ground engaging foot which can be anchored to the ground if desired. The legs 62, 64 are interconnected with a pair of shelf members 68 provided below the base member 12 which acts as a brace for the legs 62, 64 whilst also providing shelf

space for tools. Shelf members 68 clip onto the leg 62, 64 and may be easily dismantled to disconnect the legs 62, 64 from the base member 12 if necessary. Thus the clamping device may be readily modified to a bench-mounted configuration if desired. Figure 6 illustrates an example of the clamping device in a bench-mounted configuration. For this purpose, the support structure of the clamping device preferably includes a plurality of legs 70 fitted to an underside of the base member 12 to permit bench-mounting. In the embodiment of Figure 6, the actuating mechanism is provided in connection with the first jaw 14 rather than the second jaw 22 as in the embodiment of Figure 1.

A second example of a clamping device is shown in general layout in Figure 5. Here, two moveable jaws 100 and 102 are mounted on a carrier member 104 of similar form to that of the first example. Carrier member 104 in this example is itself mounted on a base member 106 so that it's edges curl around the edges of the frame and so that the carrier member can slide on the base member. Instead of teeth on the edges of the carrier member, rows of holes 106 and 108 in the ribs and web of carrier member 104 are formed to take locking pins (not illustrated) .

Figure 7A and 7B illustrate a third embodiment of the clamping device having a support structure 80 designed for bench-top mounting of an elongate base member 82. A first jaw 84 is fixed to one end of the base member 82. In this embodiment a carrier member 86 is slidable mounted on the base member 82 and it has in turn a slide member 88 slidably mounted thereon supporting a second jaw 90 mounted thereon. Figure 7B illustrates the manner in which the clamping device can be pivoted through 90° of the support structure 80 without in any way adversely affecting the operation of the first and second jaws 84, 90. Figures 8A and 8B illustrate the manner in which the carrier member 86 and slide member 88 can be slidably moved and locked in position to accommodate work pieces of large dimensions between the first and second jaws.

Figures 9A and 9B illustrate an alternative actuating mechanism which may be used in the previous examples. In this case, slide member 110 comprises a central body 112 which is integral with the slide member which is mounted on base member 116. Body 112 is horizontally bored to take a bolster pin 116 on which a bolster plate 118 is mounted, pin 116 being slidable in body 112. Pin 116 and bolster 118 can be forced outwards from body 112 by rotation of an eccentric cam 120 mounted on shaft 122, the cam and shaft being rotated for that purpose by lever 124 and handle 126. Preferably, pin 116 can telescope or be compressed and contains a hydraulic or spring-controlled constant-force device (known in the art) which limits the force which can be applied to the work-piece. Such a device therefore acts to ensure that, as long as slide member 110 is within one tooth or increment of the work-piece, the same force will be applied to the work-piece irrespective of it's exact size.

As illustrated in Figures 9A and 9B, slide member 100 is adapted for mounting on the device of the second embodiment shown in Figure 5, the ribs of bed 116 being provided with rows of holes 128 and locking-pin assemblies 130. It should be noted that a locking-pin assembly is mounted on each side of foot 114 above and in line with the corresponding row of holes 128. Also, it is to be noted that the same type of locking-pin assembly may be mounted on the web of the 104 in line with the central row of holes 108

(Figure 5) . When used on a jaw, assemblies 130 enable the jaw to be locked to the carrier member, and when used with the carrier member, they enable the carrier member to be locked to the base member 106 in Figure 5.

From the above detailed description of several embodiments of the clamping device according to the invention it will be appreciated by those skilled in the mechanical art that numerous variations and modifications may be made to the clamping device, in addition to those already described, without departing from the basic inventive concepts. All such variations and modifications are to be considered within

the scope of the present invention the nature of which is to be determined from the foregoing description and the appended claims.