Cam actuated clamp apparatus

[0001] The present disclosure relates to clamps, and more particularly to a spring clamp that can be used to clamp two work pieces together through a single motion with one hand.

[0002] Clamping mechanisms are used in a wide variety of applications to clamp two or more work pieces together during various types of manufacturing and assembly operations. One such clamp is often used in the assembly of various components used in commercial and military aircrafts. For example, the construction of interior panels used in commercial aircraft often requires the use of a plurality of clamps to hold two or more panels together during an assembly or manufacturing operation. The clamps often have to be taken off and then placed on work pieces a number of times during the construction process. Thus, with conventional clamps a significant degree of physical effort is often expended by workers simply placing numbers of clamps on to work pieces, and then being required to remove the clamps from the work pieces, then repeating this operation a number of times. The physical effort required to place and remove clamps from the work piece also can add to the overall manufacturing time.

[0003] One clamp developed to overcome the above drawbacks is disclosed in U.S. Pat. No. 6,832,416, assigned to the Boeing Company. These clamps make use of a living hinge and a camming number that allows the clamp to be quickly and easily attached to an edge of one or more work pieces with a minimal degree of physical effort by the user.

[0004] Nevertheless, it would further be highly desirable to provide a spring clamp that can be opened quickly and easily by the user and placed over the edges of one or more work pieces with a minimal degree of physical effort by the user, and can further accommodate work pieces of significantly varying thicknesses.

[0005] The present disclosure is related to a clamp apparatus that can be easily opened by a user with a single hand, and which can also be placed into a clamped position over one or more work pieces with a single motion of a component on the clamp. The clamp further can accommodate a work piece, or work pieces, having significantly varying thicknesses.

[0006] In one form, the clamp includes a first jaw having a fulcrum, and a second jaw having a projecting arm. When the clamp is in a closed configuration without a work piece placed between the jaws, the projecting arm contacts the fulcrum and the first jaw can be rotated about the projecting arm relative to the second jaw. An actuating lever is pivotally coupled to one of the jaws and includes a manually graspable portion and a camming portion. At least one biasing spring is coupled between the two jaws under tension. The clamp may be opened by the user simply grasping the manually engageable proportion and lifting the clamp, in which the weight of the clamp itself enables the jaws to be moved into an open configuration. The jaws may be clamped over one or more work pieces placed there between by the operator simply moving the actuating lever, via the manually graspable portion, into a second position. Since the jaws are not physically coupled together at the area where the projecting arm contacts the fulcrum, the jaws being held to one another only by the biasing spring, the jaws can be separated away from one another to a greater degree to accommodate work pieces having significantly varying thickness. The amount of effort required to move the actuating lever between its first and second positions is relatively small, thus enabling the user to place the clamp in its clamped and unclamped orientations with a minimal degree of physical effort.

[0007] In one embodiment the actuating lever includes a plurality of spaced apart camming lobes. In another embodiment the jaws include jaw portions that have a common arcuate shape so as to be able to engage one or more arcuately shaped work pieces.

[0008] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating various preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

[0019] The following description of various embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0020] Referring to FIGS. 1-3, there is shown an embodiment of a clamp 10. The clamp 10 includes a first jaw 12, a second jaw 14, and at least one spring 16 coupled under tension to the jaws 12 and 14 via end portions 16a and 16b of the spring that extend through holes 17a and 17b in the jaws 12 and 14. In this example a pair of springs 16 are illustrated, but it will be appreciated that a single spring could be included with only minor modifications to the embodiments shown in FIG. 1. Such modifications would involve locating the spring along a mid point of the jaws 12 and 14 and selecting a spring constant necessary to provide the biasing force needed for the anticipated clamping operations.

[0021] The first jaw 12 of the clamp 10 also includes a fulcrum 18 that contacts a distal end 20 of a projecting arm 22 of the second jaw 14. The projecting arm 22 is also shown in FIG. 5. Jaw 12 further includes a jaw portion 24 and an end portion 26, while the second jaw 14 includes jaw portion 28 and second end portion 30. An actuating lever 32 has a manually graspable portion 34 and a cam lobe 36. The actuating lever 32 is positioned partly within a notched area 38 (shown also in FIG. 4) of the first jaw 12 and is pivotally coupled to the first jaw 14 via a pivot pin 40 that extends through portions of the first jaw 12 and through the actuating lever 32. The actuating lever 32 is coupled to the first jaw 12 such that the manually graspable portion 34 projects outwardly from the first jaw 12, and such that the cam lobe 36 is positioned generally between the end portions 26 and 30 of the jaws 12 and 14, respectively, and such that the cam lobe 36 is in contact with an inner surface 42 of the second jaw 14.

[0022] Referring to FIG. 3, clamp 10 is shown in a closed position but without a work piece, or work pieces, positioned between the jaws 12 and 14. Since the springs 16, which in this example are coil springs, are coupled under tension between the jaws 12 and 14, the distal portion 20 of the projecting arm 22 is held in contact with the fulcrum 18. The fulcrum 18 essentially forms a groove extending along the width of an inner surface 43 of the jaw 12, while the projecting arm 22, in this embodiment extends along the full width of the second jaw 14. The springs 16 are coupled at longitudinal points along each of the jaws 12 and 14 that are in between the fulcrum 18 and the end portion 26, and in between the projecting arm 22 and the end portion 30, but adjacent the fulcrum 18. Cam lobe 36 is shaped such that a slight over center action occurs when the actuating lever 32 is moved between a closed position, shown in FIG. 3, and an open position shown in FIG. 6. The springs 16 provide a small degree of force to urge the end portions 26 and 30 towards one another, to thus hold the actuating lever 32 in the position shown in FIG. 6, once a predetermined point of travel is moved past when the user is rotating the actuating lever 32 in a counter-clockwise direction in the drawing of FIG. 6. Optionally, a pin 37 could be inserted through the jaw 1 adjacent to the fulcrum 18. This would effectively “deepen” the fulcrum and limit any tendency of the jaw 12 to slide forwardly, relative to jaw 14, when the fulcrum 18 is out of contact with the distal end 20 of the projecting arm 22 while clamping a thick workpiece.

[0023] Referring further to FIG. 6, to move the clamp 10 into an open position, the user merely grasps the manually graspable portion 34 and lifts the clamp 10. The weight of the jaws 12 and 14, taken with the coupling of the actuating lever 32 at the end portion 26 of the first jaw 12, enables the springs 16 to help assist moving the jaws 12, 14 into an open configuration as the actuating lever 32 is rotated in a counter-clockwise direction in FIG. 6, relative to the jaws 12 and 14. Thus, the operation of opening the clamp 10 is extremely easy for the user, since the clamp opens essentially automatically due to its own weight when the operator lifts the clamp while holding the manually graspable portion 34.

[0024] Referring to FIG. 7, the clamp 10 is illustrated in a clamped configuration holding a pair of work pieces 44 clamped against one another. The user places the clamp 10 in the orientation shown in FIG. 7 by initially placing the work piece, or work pieces 44, between the jaw portions 24 and 28. The length of the projecting arm 22 is such that at least a minimum predetermined width opening is provided when the clamp 10 is in its open configuration (FIG. 6). However, since the upper and lower jaws 12, 14 are not positively coupled together via a fixed link or fixed component, the jaws 12 and 14 may still be spread apart from one another if a work piece or work pieces having an overall thickness that is greater than the spacing between the jaws needs to be clamped. Essentially, the first jaw 12 can be viewed as “floating” relative to the second jaw 14 because of the abutting contact of the distal portion 20 and the fulcrum 18. This enables an even wider degree of adjustability of the clamp 10 to accommodate an even wider range of thicknesses of work pieces that require clamping.

[0025] Referring further to FIG. 7, the clamp is secured to the work piece by placing the work piece between the jaws 12 and 14 and then merely rotating the actuating lever 32 clockwise in the drawing of FIG. 7. This essentially is a pushing motion which rotates the actuating lever 32 to cause the cam lobe 36 to spread apart the end portions 26 and 30 of the jaws 12 and 14, respectively. The springs 16 provide a biasing force that not only helps to hold the actuating lever 34 in the position shown in FIG. 7, but also jaws 12 and 14 under tension over the opposite surfaces of the work pieces 44. The shape of the cam lobe 36, taken in connection with the tension force provided by the springs 16, enables an on-center, or slightly over-center action to be achieved when moving the actuating lever 32 into the position shown in FIG. 7. When the actuating lever 32 is moved counter-clockwise in the drawing of FIG. 3 past a predetermined point, the spring 16 begins to assist opening of the jaws 12 and 14. When the actuating lever 32 is moved in a clockwise direction to, or just slightly past, a predetermined point, the springs 16 then operate to assist in holding the actuating lever 32 in the position shown in FIG. 6.

[0026] The degree of clamping force provided can be controlled by selecting springs 16 having desired spring constants. The shape of the cam lobe 36 and the spring constant selected can be such to enable the clamp 10 to be unclamped from the workpiece(s) 44 simply by shaking the work piece(s) slightly, or even by holding the workpiece(s) at an angle that allows gravity to pull the actuating lever 32 into the open position. In this manner, a plurality of the clamps 10 can be quickly removed simultaneously from the workpiece(s) 44. Of course, if a high degree of clamping force is required, then a suitable spring constant can be selected to achieve the needed clamping force.

[0027] The jaw portions 12 and 14 may be made of any suitable material such as aluminum, steel, high strength plastic, etc. The actuating lever 32 may be made from similar materials.

[0028] Referring to FIGS. 8 and 9, a clamp 100 in accordance with an alternative embodiment is illustrated. The clamp 100 is constructed along the same principles as the clamp 10 but includes an actuating lever 102 having an elongated shaft 104 with a plurality of spaced apart camming portions 106 affixed thereto. Jaw portions 108 and 110 are also elongated, and the camming portions 106, due to being spaced apart, enable a uniformed force to be applied to end portions 112 and 114 of jaws 108 and 110 during opening and closing movements of the clamp 100. In this embodiment, multiple springs 116 may also be incorporated to provide a uniform clamping force.

[0029] With further reference to FIG. 9, the jaws 108 and 110 have a common arcuate shape that better allows the jaws to grasp onto a work piece having an arcuate shape. Thus, if the curvature of the work piece is known in advance, the jaws 108 and 110 could be formed with a similar or identical curvature to even more effectively clamp the work piece (or work pieces) between the jaws 108 and 110. Also while the jaws 12 and 14 of the clamp 10 have been illustrated as having flat surfaces along the jaw portions 24 and 28, it should be appreciated that the jaw portions 24 and 28 could also be formed with a common arcuate shape, or even a different non-planar shape, to even more effectively clamp a work piece.

[0030] The various embodiments described herein all provide a clamp that can be opened automatically simply by the user grasping a portion of an actuating lever and lifting the clamp into position to be placed on a work piece or work pieces that need to be clamped together. The clamps described herein can also be closed through a single rotational movement of the actuating lever with a single hand of the user once the work piece, or work pieces, have been placed between the jaws of the clamp. This enables the clamp to be quickly and easily secured over a work piece, as well as quickly and easily removed from the work piece with a minimal effort in both the clamping and unclamping movements performed by the user. This enables each of the clamps described herein to be more quickly and easily attached to a work piece, as well as more quickly removed from the work piece.

[0031] While various embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.