Work material clamp for use with cutting machines

A clamp for use with a cutting machine, the clamp comprising: a clamp frame; a low profile clamp head operatively connected to the clamp frame, wherein the clamp head has a clamping surface for pressing on a work surface of a work piece to hold said work piece; and a fixing element, operatively connectable to the clamp frame, for providing a clamping force to the clamp head by fixing the clamp to a support base for the work piece. In embodiments, the clamp head may have a low profile clamp head, made of plastic to prevent damage to a cutting bit.

FIELD OF THE INVENTION

This invention relates to the field of cutting machines, and in particular, to accessories cutting machines.

BACKGROUND OF THE INVENTION

There are a variety of cutting machines commonly in use. Among them are lathes, mills, routers and grinders. More recently, CNC (Computer Numerical Control) machines, which are computer controlled for high precision have recently risen in popularity. Such machines typically operate continuously, relying on the computer control. Such machines, and other machines, involve a bit or other cutting tool cutting repeatedly into a work piece.

It is typical for the work piece to be clamped in place to permit precision cutting of the work piece. The work piece is, in the example of CNC machines, typically clamped to a wasteboard. A wasteboard is a piece of material under the work piece, to which the work piece is clamped, which may be incidentally cut during cutting of the workpiece. It will be appreciated, however, that the work piece may be clamped in other configurations, to other kinds of support bases.

Two typical kinds of wasteboards are threaded insert wasteboards, and T-track wasteboards. Both kinds of wasteboards are configured to facilitate attachment of clamps to the wasteboards, to provide the clamping force for holding the workpiece on the wasteboard. In the most typical configuration, a clamp is fixed to the wasteboard, and the clamp presses down on the work piece to hold it in a fixed position on the wasteboard.

One problem that sometimes arises with such clamps is that the user misjudges the position of some of the cuts to the workpiece, with the result that the machine bit cuts into the clamp, thus damaging the bit.

SUMMARY

What is desired is a clamp that ameliorates or reduces one or more deficiencies of at least some prior art clamps.

Therefore, according to an aspect of the present invention there is provided a clamp for use with a cutting machine, the clamp comprising: a clamp frame; a clamp head operatively connected to the clamp frame; and a fixing element, operatively connectable to the clamp frame, for providing a clamping force to a work piece by fixing the clamp to a support base; wherein the clamp head is composed of plastic to prevent damage to cutting bits contacting the clamp head. Optionally, the clamp frame comprises a pair of metal pins, and a frame stiffening element connecting the two pins. Optionally, the fixing element comprises a screw, and the support base comprises a threaded insert wasteboard. Optionally, the clamp further comprising a lever operatively coupled to the fixing element for actuating the fixing element. Optionally, the support base comprises a T-track wasteboard, and the fixing element comprises a nut for attaching to a screw that is attached to the T-track wasteboard.

According to another aspect of the invention, there is provided a clamp for use with a cutting machine, the clamp comprising: a clamp frame; a clamp head operatively connected to the clamp frame; and a fixing element, operatively connectable to the clamp frame, for providing a clamping force to a work piece by fixing the clamp to a support base; wherein the clamp head is operatively attachable to and detachable from the clamp frame by hand. Optionally, there is provided a clamp kit comprising this clamp, and a second clamp head, operatively connectable to the clamp frame, for replacing said clamp head. Optionally, the frame comprises a pair of metal pins, and wherein the clamp head is slidable on to and off of the pins. Optionally, the clamp head is composed of plastic.

According to another aspect of the invention, there is provided a clamp for use with a cutting machine, the clamp comprising: a clamp frame; a clamp head operatively connected to the clamp frame, the clamp head having a clamping surface for pressing on a work surface of a work piece to hold said work piece; and a fixing element, operatively connectable to the clamp frame, for providing a clamping force to the clamp head by fixing the clamp to a support base for the work piece; wherein the clamp head is a low profile clamp head. Optionally, the clamp head extends less than 2 centimetres above the work surface. Optionally, the clamp head extends less than one centimetres above the work surface. Optionally, the clamp frame has a profile no higher than the clamp head.

DETAILED DESCRIPTION

The invention will be described in detail with reference to a CNC mill/router. It will be appreciated that the invention is not limited to such a router. The invention is applicable mutatis mutandis to other cutting machines.

Referring now toFIG.1, a support piece for a work piece, in the form of a waste board12is shown. The waste board12is positioned to support a workpiece10. The workpiece10is positioned to facilitate work on the workpiece10by a cutting tool (not shown) associated with a CNC machine (not shown).

The waste board12shown inFIG.1is a threaded insert waste board. Numerous threaded inserts18are shown on the waste board12. In the example waste board shown inFIG.1, threaded inserts18are provided in a grid pattern to provide a wide variety of clamping locations.

Two clamps16are shown inFIG.1. As will be described in greater detail below, clamps16are holding work material10on the waste board12. The clamping force used by clamps16is provided by attachment of clamps16to the waste board12.

In the example shown inFIG.1, the clamps16are attached to waste board12by a fixing element, in the form of a screw being screwed into a threaded insert18in waste board12. However, it will be appreciated that the invention also comprehends use of a T-track waste board12. In T-track waste board12, the attachment would be by means of a screw extending out of the waste board with its head positioned inside the T track, and a nut fixing the clamp16to that screw, thus fixing the clamp to the waste board12.

Referring now toFIGS.2and3, the example clamp16comprises a clamping head20having clamping surface19, a clamp frame22, and a height adjustment assembly. InFIGS.2and3, the height adjustment assembly comprises a jack screw24and a screw receiving socket26within frame stiffening end piece28.

The clamp16further comprises a fixing element. In the embodiment ofFIGS.2-3, the fixing element comprises a screw30, with washer33, configured to fix the clamp16in position against the waste board12. Clamp16ofFIGS.2-3comprises a selectively positionable socket34. As shown in these figures, socket34includes through-hole35for receiving the screw30. Socket34fits into frame22, and is slidable along frame22to facilitate adjustment of the position of screw30. Preferably, socket34fits with a snap fit onto and between pins21, so that it remains attached to them while being slidable along the frame22. Socket34is configured to transmit the clamping force from screw30to frame22, which is turn transmits clamping force to clamping head20to press on work piece10to hold it in place.

It will be appreciated that the socket34being selectively positionable is helpful because there are a limited number of threaded inserts, meaning that there are a limited number of points of connection to the waste board12. The position of the screw30therefore may need to be adjusted.

It will further be appreciated that the invention comprehends the absence of a socket34. Screw30and frame22may be sized, shaped and mutually configured so that screw30acts directly on frame22to provide clamping force to clamp16. Other configurations of fixing element are also comprehended.

In the preferred embodiment, the frame22comprises a pair of spaced metal pins21. Preferably, the metal comprises alloy steel, or stainless steel. It will be appreciated that, since the frame22transmits clamping force from the fixing element to the clamping head20, and since it is desirable to provide high clamping force, it is therefore also preferred that frame22to be made of the material capable of withstanding a high clamping force without bending or otherwise failing. In some embodiments, pins21are inserted into receiving holes in a frame stiffening element, to provide a stiff frame for receiving and transmitting clamping force.

It will be appreciated that, in use, clamping head20is typically positioned on the surface of workpiece10that is being engaged by the cutting tool. In particular, clamping surface19typically presses against that surface of the work piece. As such, if the path of the cutting tool is misjudged by the user, the cutting tool may cut into clamp16, and most likely, clamping head20. In the prior art, such a collision between the cutting tool and the clamp might lead to the cutting tool being seriously damaged. Specifically, in the prior art, clamps and clamping heads are made of metal. Thus, when the cutting tool contacts a mental clamp, it is often damaged beyond repair.

However, in the preferred embodiment, clamping head20is made of plastic. Thus, if the cutting tool contacts the clamping head20of the preferred embodiment, it is much more likely not to be damaged. The reason is that the cutting tool, generally made of metal, can generally cut into the plastic without being damaged by it. It will be appreciated, however, that other materials besides plastic are comprehended. Less preferably, a hard material such as metal may still be used. More preferably, a non-plastic material may be used which, like plastic, is soft enough not to damage the cutting tool when the cutting tool cuts into it.

In the preferred embodiment, the head20includes space for receiving frame22. In the preferred embodiment, this receiving space comprises two slots, each of which receives a pin21of frame22. Preferably, the slots extend only part way into the clamping head20, so that the forward portion of the clamping head20, beyond the pins21, can clamp the workpiece, while the pins21of frame22are positioned off of the workpiece. This lessens the probability that the cutting tool would make contact with the pins of frame22. As can be seen inFIG.2, the preferred clamping head20has viewing holes36that show externally the ends of the pins21. Using these holes, the user can position the head20so that it clamps on to the work piece, while the frame22, including the pins21, are positioned off the work piece, and not positioned at, on or above the work piece.

Referring inter alia toFIG.6, preferably, the clamp head20is slidable on to and off of the pins21comprising frame22. Clamp head20preferably fits on to pins21by a friction fit or pressure fit. Thus, clamp head20can be replaced with a new clamp head20, which is beneficial if clamp head20is damaged by contact with the cutting tool; under these circumstances, damaged clamp head20can be pulled off frame22by hand, and new clamp head20can be slid on to frame22. In this regard, the clamp of the present invention may provided in a kit, with the kit containing the clamp, and at least a second clamp head20as a replacement.

It will be appreciated that other modes of attachment of clamp head20to frame22are comprehended by the invention. Less preferred is a form of attachment and detachment that does not permit easy replacement of head20. More preferable is any form of attachment and detachment permitting the clamp head to be pulled off and pushed on solely by hand, without requiring cutting, breaking, heating, or any other process not done solely by hand.

In the prior art, clamps are bulky and high profile. The clamp head herein preferably has a low profile. It will be appreciated that, in some applications, the cutting tool will be cutting deeply into the work material in the vicinity of the clamp head20. If the clamp head20is high profile—if it extends too far upward from the surface of the work material through which the cutting tool enters—then there is a substantial risk that the spindle carrying the cutting tool will contact clamp head20, particularly on a deep cut. If this happens, then the spindle could be damaged. Also, this undesired contact could deflect or misposition the cutting tool, thus causing the cutting to be incorrectly done. In the prior art, there has not been success in creating a low profile clamp which also clamps consistently effectively, for example, for CNC machines.

In a preferred embodiment, the clamp head20has a profile of 2 centimeters or less above the work piece, when the clamp16is in use. In other words, the highest point of the clamp head20is 2 centimeters or less above the work surface of the workpiece, that is, the surface through which the cutting tool enters. In a more preferred embodiment, the profile is 1 cm or less. In a preferred embodiment, the profile of the frame22is less than or equal to the profile of the clamp head20.

In the example clamp ofFIGS.2and3, the height adjustment assembly operates to adjust the height of the clamp16off of the wasteboard12by spacing the clamp16off of the wasteboard12. It will be appreciated that height adjustment is useful because workpieces can be of different thicknesses. Therefore, effective clamping of a thicker workpiece may require a greater height for the clamp off of the wasteboard, while effective clamping of a thinner workpiece may require a lesser height for the clamp off of the wasteboard.

The height adjustment assembly comprises jack screw24and socket26. The height is adjusted by adjusting the length of screw24outside of socket26. The further the screw24is screwed into socket26, the smaller the length, and the height. The less the screw24is screwed into socket26, the greater the length, and the height. The head of screw24abuts wasteboard12to provide a point of contact for supporting clamp16at the desired height. The height adjustment function of the assembly is shown, for example, inFIG.1. As can be seen, screw24is adjusted in height to position the clamp head20such that it can push down on work piece10to hold it in place.

Referring now toFIG.4, a version of clamp16is shown which operates with T-track wasteboards. The fixing element in this embodiment comprises nut31, which screws onto a screw (not shown) extending upward from the T-track. Preferably, nut31is rotatable by hand, and by screwing nut31onto a screw extending from the T-track, the clamp16is fixed in position, and holds the workpiece in position. Preferably, nut31is selectively positionable, similar to socket34. The reason is the same—t-tracks do not cover the entire wasteboard, and therefore there are a limited number of attachment positions. Therefore, it is beneficial to have adjustability.

FIG.5shows an exploded view of part of clamp16, with the socket34shown apart from the frame22.

FIG.7shows an alternate embodiment of clamp20. In this embodiment, configured for use with a t-track wasteboard, lever38is mounted to socket34and frame22. Lever38is used to rotate socket34so as to cause it to screw onto a screw (not shown) attached to the t-track. This embodiment operates somewhat similarly to the embodiment ofFIG.4, but further includes lever38to make the rotation of socket34, and connection to the t-track screw, easier. When not in use, lever38may be folded down on to clamp16to provide a low profile.

FIG.8shows an alternate embodiment of the invention. This embodiment includes a clamping head that abuts the corner of the workpiece, rather than the top surface of the workpiece, as the embodiment ofFIG.2does. Thus, the clamping head20′ ofFIG.8has a shape designed to receive a squared-off corner of a workpiece.

The embodiment ofFIG.8could also be used to abut the side or edge of a workpiece, with the clamping surface40abutting that side or edge. In such a usage, the corner-receiving shape shown inFIG.8would not be required.

FIG.9shows an alternative embodiment of the clamp. Lever38is pivotally mounted to screw30and attached by screw30to the waste board. Lever38is rotatable relative to screw30. Operatively connected to lever38is a force transmitter sized shaped and positioned to impart a force (generated by rotation of lever38), to frame22to urge clamp16along the wasteboard. The clamp head20can thus be moved to force surface40to firmly abut a side or edge of the workpiece to hold it in place. The clamp can be loosened by rotation in the opposite direction. The force transmitter may comprise, for example, a gear or the like, mating with a gear or teeth or the like on pins21to facilitate the transmission of rotational force from lever38to clamp16.

In the preferred embodiment, the clamp16is modular. Thus, the frame and clamp head can be used with different fixing elements. These would include screws (or any fixing element that operates with threaded insert wasteboards), hand nuts (or any fixing element that operates with t-track wasteboards), a top-positioned cam lever (as shown, for example, inFIG.7), or a side cam lever. Thus, clamp may be provided in a kit that includes the frame, clamp head and two or more fixing elements, possibly including the aforementioned fixing elements.

While the foregoing preferred embodiments of the present invention have been set forth in considerable detail for the purpose of making a complete disclosure of the invention, it will be apparent to those skilled in the art that other embodiments described herein are comprehended by the broad scope of the invention as defined in the appended claims.

The above references to U.S. patents and patent publications in all sections of this application are herein incorporated by references in their entirety for all purposes. Components illustrated in such patents may be utilized with embodiments herein.

Each feature disclosed in this specification (including references incorporated by reference, any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any incorporated by reference references, any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The above references in all sections of this application are herein incorporated by references in their entirety for all purposes.

Although specific examples have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement calculated to achieve the same purpose could be substituted for the specific examples shown. This application is intended to cover adaptations or variations of the present subject matter. Therefore, it is intended that the invention be defined by the attached claims and their legal equivalents, as well as the following illustrative aspects. The above described aspects embodiments of the invention are merely descriptive of its principles and are not to be considered limiting. Further modifications of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention.