The invention relates to an adapter used with a swiveled clamp head to clamp workpieces together in a direction transverse to the clamp direction.
With respect to woodworking apparatuses such as cutting devices (i.e., table saws, routers and band saws), clamps may be used to secure workpieces directly to worktable tops. Conventionally, clamps that work in conjunction with a tabletop will clamp in a direction normal to the upper surface of the table top, thereby clamping the workpiece down to the table (or onto another workpiece disposed on the table etc.) An example clamp of this type is an F-type clamp.
A first prior art F-type clamp 10 and an identical second prior art F-type clamp 10, are illustrated in
Each clamp 10 can secure a respective workpiece (not shown) between the swivel clamp head 24 and the surface 38 of the tabletop 32. The clamps 10 clamp in a clamp direction 40 that is essentially parallel to the normal direction 36. The clamp direction 40 may deviate from the normal direction 36 slightly due to flex of the first post 14, the second post 16, the guide arm 18, and/or a loose fit between the second post 16 and the slot 30 in response to clamping force. However, the majority of the clamping force seen by the workpiece is normal to the surface 38. Consequently, when two workpieces are to be clamped together side-by-side on the worktable 32, since the majority of the clamping force is normal to the surface 38, friction is essentially the only force holding the parts to each other.
Certain procedures require relatively high side-to-side (e.g. lateral) holding forces so that the workpieces do not move relative to each other. To achieve these relatively high forces, the clamps may be tightened enough that the surface of the workpiece is damaged, or the clamp is stressed. In certain instances, the F-type clamp simply cannot be tightened enough to provide the normal clamping force necessary to achieve the required lateral clamping force. Other clamp configurations have been devised to address this. For example, a separate linear clamp oriented horizontally may be applied to the workpieces. However, in such an arrangement the workpieces may lift off the worktable 32. A stable clamping arrangement may then require several clamps at various orientations and locations. Consequently, there is room in the art for improvement.
The invention is explained in the following description in view of the drawings that show:
The Inventor has devised a clamp head adapter that can be placed on a swivel clamp head of a clamp used to clamp a workpiece to a worktable. The innovative clamp head adapter enables the lone clamp to provide not only a normal clamping force to the workpiece, but also a lateral clamping force. The normal clamping force clamps the workpiece to the worktable and the lateral clamping force can be used to clamp the workpiece laterally to one or more additional workpieces. This reduces the number of clamps necessary to perform many operations on the workpieces, thereby simplifying and speeding the process.
As can be seen in
In an embodiment, a first side 160 of the groove 110 extends from the vertex 130 to the first corner 138 and includes a straight portion. However, the first side 160 need not be straight but could be concave instead. In an embodiment, the first bevel angle 132 is sixty (60) degrees. Other angles are acceptable so long as they are in accord with the teachings disclosed herein. In an embodiment, a second side 162 of the groove extends from the vertex 130 to the second corner 154 and includes a straight portion.
In an embodiment, the groove 110 is asymmetric, meaning that the first bevel angle 132 does not equal the second bevel angle 150. In various embodiments, the second bevel angle 150 will be less than the first bevel angle 132. In an embodiment, the second bevel angle 150 is less than forty-five (45) degrees. In an embodiment, the second bevel angle 150 is less than thirty (30) degrees. In an embodiment, the first bevel angle is sixty (60) degrees, the second bevel angle 150 is twelve (12) degrees, and the resulting groove angle 156 is seventy-two (72) degrees. In an alternate embodiment, the second side 164 (shown as a dashed line) of the groove 110 extends from the vertex 130 to the second corner 154 and is concave.
The second groove 116 includes a vertex 166, a first bevel angle 168 between a normal line 170 normal to the body surface 112 and a first side 172 between the vertex 166 and a first corner 174 of the second groove 116. The second groove 116 further includes a second bevel angle 176 between the normal line 170 and a second side 178 between the vertex 166 and a second corner 180 of the second groove 116. The first bevel angle 168 and the second bevel angle 176 form the second groove angle 182. In an embodiment, the second groove 116 is symmetric, meaning that the first bevel angle 168 and the second bevel angle 176 are equal. In an embodiment, the second groove angle 182 is one hundred twenty (120) degrees. Other groove angles known to the Artisan are possible. Moreover, the second groove angle 182 may be asymmetric in accord with the teachings related to the groove angle 156. When both the groove 110 and the second groove 116 are asymmetric, they may be the same or different from each other. The second groove 116 may be oriented transverse to the groove 110 at any angle, including perpendicular.
In
Once the second corner 154 contacts the side surface 216, the second corner continues to move downward along the side surface 216 as the first workpiece 184 moves to the left. When the second corner 154 moves downward along the side surface 216 as the first workpiece 184 moves, the first corner 138 begins to move back toward the initial contact point 200. Where the first corner 138 comes to rest depends on when the first workpiece 184 contacts the fixed workpiece 186, at which time the configuration becomes interlocked in place. For example, if the gap 204 is very small and the first workpiece 184 abuts the fixed workpiece 186 right away, the first corner 138 may not travel as for to the right as it traveled to the left. In this instance, the first corner 138 will be to the left of the initial contact point 200 as is shown in
This results in the first clamping configuration 210 shown in
The first side 160 of the groove 110 may become flush with the upper surface 202 of the first workpiece 184 at the moment the first workpiece 184 abuts the fixed workpiece 186. In such a scenario, further lowering of the swivel clamp head 24 may be unnecessary and/or detrimental in that further lowering could over rotate the clamp head adapter 100 and perhaps damage an apex 224 of a top right corner region 226 of the first workpiece 184, or even damage more of the corner region 226. However, in this scenario the normal clamping force 218 and the lateral clamping force 220 will be minimal.
Alternately, the first side 160 of the groove 110 may not yet be flush with the upper surface 202 of the first workpiece 184 at the moment the first workpiece 184 abuts the fixed workpiece 186, or the first side is concave as shown by dashed line 160A. If the swivel clamp head 24 is lowered farther, (optionally until the first side 160 rests flush atop the upper surfaced 202), the second corner 154 will want to continue moving to the left due to the rotation of the swivel 190. In an embodiment suitable for soft materials such as wood, the second corner 154 may yield to the unmoving side surface 216 to avoid damaging the side surface 216. Accordingly, in an embodiment, at least one of the second corner 154, a region around the second corner 154, and the entire clamp head adapter 100 is made of the resilient material such as plastic or rubber etc. In
Alternately, for applications where damage is less of a concern, such as if the workpiece is composed of a metal or the like, the clamp head adapter 100 may not be composed of a resilient material. In such embodiments, the clamp head adapter 100 may be composed of a rigid material such as a metal or the like.
Accordingly, the clamp head adapter 100 may stop rotating for one of several reasons. In a first instance, the clamp head adapter 100 stops rotating when the first side 160 comes to rest flush on the upper surface 202 of the first workpiece 184. The clamp head adapter 100 may stop rotating before this if the second corner 154 can no longer yield. Depending on the swivel clamp head 24 selected, the clamp head adapter 100 may stop rotating when the swivel clamp head 24 reaches its maximum swivel angle.
The above illustrates an advantage of the asymmetry of the groove 110. By way of comparison, a conventional groove may include a symmetric groove where each bevel angle is the same, for example, forty-five (45) degrees. This yields a groove with a groove angle of ninety (90) degrees. The first side and the second side of such a groove are perpendicular to each other. As can be seen in
Stated another way, in the embodiments disclosed above the groove angle 156 is acute because if the first side 160 and the second side 162 are straight, then any groove angle of ninety (90) degrees or more will result in the corner region 226 contacting the first side 160 or the second side 162 before sufficient rotation takes place to create the lateral clamping force 220. As the clamp head adapter 100 is lowered onto the first workpiece 184, the corner region 226 would simply nest into the groove 110. In such an instance, the second corner 154 would not contact the second side 216 until the first side 160 came to rest flush on the upper surface 202. Hence, there would be no lateral movement of the second corner 154 nor any associated lateral clamping force 220.
An asymmetric groove angle was chosen to create a desired leverage and associated lateral clamping force 220. However, the groove angles need not be asymmetric to create the lateral clamping force 220. Moreover, the lateral clamping force 220 can also be created using a nonlinear groove surface.
In a broad sense, the groove 110 must at a minimum be configured to receive the ninety (90) degree corner region 226 of the first workpiece 184 when the first corner 138 and the second corner 154 contact the first workpiece 184 while the groove sides 160, 162 are set apart from the corner region 226 of the first workpiece 184 that is received/disposed in the groove 110. So long as the groove sides 160, 162 are set apart from the corner region 226 to some degree, the first corner 138 and the second corner 154 can slide along the upper surface 202 and the side surface 216 respectively due to the above-described rotation of the clamp head adapter 100 without geometric interference between the corner region 226 and the groove 110. This, in turn, enables the establishment of the lateral clamping force 220 under the principles disclosed above. This set-apart spacing between the corner region 226 and the first side 160 and the second side 162 is most visible in
Since sometimes a larger lateral clamping force 220 is desired, a first bevel angle 132 that is larger than the second bevel angle 150 is selected (e.g. an asymmetric groove angle 156) as disclosed in
In the alternate embodiment disclosed above, the first side 160A may be arcuate to enable more rotation and associated lateral clamping force 220.
In another alternate embodiment, there may not be a distinct first side and second side. Instead, a groove surface 160C may comprise any continuous or segmented shape that permits the disclosed rotation. An example groove surface 160C is arcuate and terminates on one end at the first corner 138C and at the other end at second corner 154C. The groove 110 can clearly receive the 90 degree corner region 226 of the first workpiece 184 while the first corner 138C and the second corner 154C move along the upper surface 202 and the side surface 216 through a wide range of positions. Any shape of the groove surface 160C between the first corner 138C and the second corner 154C that permits this movement is permissible and within the intended scope of this disclosure.
In addition, for embodiments of the clamp head adapter 100 with a straight first side 160 and a straight second side 162, an acute angle (e.g. less than ninety (90) degrees) is necessary because the first workpiece 184 has a ninety (90) degree corner region 226. If the workpiece has a corner region with a different angle, a different groove angle could be used. For example, if the workpiece corner region was one hundred twenty (120) degrees and the first side 160 and the second side 162 are straight, then the groove angle could be any angle less than one hundred twenty (120) degrees. The reason for this is the same reason an acute groove angle 156 is selected for a workpiece with a ninety (90) degree corner region 226. So long as the groove angle is less than the angle of the corner region of the workpiece, the lateral clamping force will be established. Making the groove angle asymmetric will simple increase the leverage and lateral clamping force. Symmetric ninety (90) degree and greater grooves are known in the art. However, the asymmetric ninety (90) degree and greater grooves disclosed herein appear to represent an improvement in the art.
As before, the second clamping configuration 230 generates a normal clamping force 218 and a lateral clamping force 220. However, by virtue of the flex and slack in the clamp 10, the lateral clamping force 220 may be greater. This is because the clamp is now angled relative to the vertical reference line 194 such that the force it creates has a horizontal (e.g. lateral) component not present when the clamp is aligned with the vertical reference line 194. Moreover, the flex of the clamp also contributes to the lateral clamping force 220. The amount of lateral clamping force 220 that can be generated thereby depends on several factors, including (but not limited to) the initial relative position of the clamp 10 to the workpiece, the mechanical characteristics of the clamp 10, the amount the swivel clamp head 24 is lowered onto the first workpiece 184, the values selected for the first bevel angle 132 and second bevel angle 150, and a resilience of the material selected for the clamp head adapter 100.
The above examples of how the clamp head adapter 100 and the first workpiece 186 are initially positioned are not meant to be limiting. The clamp may be positioned in a variety of locations and the clamp head adapter 100 may likewise be initially positioned in a variety of ways relative to the first workpiece 184. For example, the clamp head adapter 100 may be initially positioned such that the first corner 138 and the second corner 154 are in contact with the first workpiece 184 before the clamp is tightened. Further, the first workpiece 184 may or may not initially abut the fixed workpiece 186.
The above-described principles are understood to apply but are not intended to limit the principles under which the clamp head adapter may be used.
As disclosed above, the Inventor has devised an innovative yet simple clamp head adapter that can be used to simplify how workpieces can be secured together. This can save time and effort and thereby reduce costs associated with securing the workpieces. Consequently, the clamp head adapter represents an improvement in the art.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
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