Patent Grant
6932335
1. Field of the Invention
The present invention relates to clamps generally, and more particularly, relates to a locking manual hold down clamp.
2. Description of Related Art
Toggle and hold down clamps have been used and known in the art for many years. A typical hold down or toggle clamp includes a clamping arm which pivots between a released and clamped position. The clamps are used to hold work pieces in place for processing, for clamping two objects to one another, or for clamping an object to a work table or other surface. Toggle and hold down clamps generally are quickly engageable and disengageable to the work piece or object being held. They also provide a considerable holding and clamping force which enables them to hold the work piece or object securely where needed.
Many of these prior art devices hold the clamp position to a variety of means, these means include maintaining the force applied to the bar or arm of the clamp. Other prior art clamps create a holding force by passing the links of the toggle clamps to an over center position, the over center position subjects the links and the pivot points of the clamp to very high loads resulting in increased wear and potential deformation of the clamp components thereby reducing the life of the clamp.
There have been some problems with some prior art clamps releasing due to vibration and other unforeseen forces during the use of the clamps. Some of these prior art clamps include several bends in their links and power arms. These bends may reduce performance and strength of the clamp by amounts up to 30 to 40 percent. Some of these clamps also include parts that have bends that are not interchangeable and have to be put together in precise positions, thus increasing the cost of labor of assembling the clamps. Also many of these prior art clamps do not include a positive locking mechanism which will ensure the clamp is locked and not capable of being opened when it is in its fully engaged position. The positive locking of the clamp is necessary in manufacturing environments where the unexpected disengagement of a clamp may produce hazards and other down time on manufacturing lines because of such unexpected releases.
Therefore, there is a need in the art for an improved locking hold down action clamp that is more robust, has greater strength and interchangeability than prior art clamps. There also is a need in the art for a locking clamp that has a positive lock that will only disengage upon user interaction with the locking mechanism of the clamp.
One object of the present invention is to provide an improved locking clamp.
Another object of the present invention is to provide a more robust locking clamp.
Still another object of the present invention is to provide a locking hold down clamp with fewer bend in the clamp parts which strengthens the individual parts and reduces their cost.
Still a further object of the present invention is to provide a clamp that has a positive locking mechanism.
Still another object of the present invention is to provide a clamp that reduces the number of different parts stamped in order to build a specific number of locking clamps.
Still a further object of the present invention is to provide a clamp that needs user intervention to disengage the clamp from its locked or fully engaged position.
It is still a further object of the present invention to provide a clamp that eliminates the need for any high cost and complex parts to create an over center stop and to create a clamp that has a locking mechanism for easy use by an operator.
To achieve the foregoing objects the locking clamp, according to the present invention, includes a base member. The clamp also includes a bar pivotally connected to the base member. A handle is pivotally connected to the base member. The clamp also includes a link connected to the handle and the bar. The locking clamp also includes a lever connected to the handle wherein the lever locks the clamp in a fully engaged position.
One advantage of the present invention is that the locking clamp is more robust and removes any bends and replaces them with straight parts in the clamp.
Another advantage of the present invention is that the locking clamp has increased strength.
Still a further advantage of the present invention is that the locking clamp provides for interchangeability of parts.
Another advantage of the present invention is that the locking clamp includes a locking mechanism that positively locks the clamp in its fully engaged position.
Another advantage of the present invention is that the locking mechanism of the locking clamp can only become disengaged with specific action taken by an operator of the clamp.
Still a further advantage of the present invention is that the locking mechanism is capable of use by both right handed and left handed operators of the clamp.
Other objects, features, and advantages of the present invention will become apparent from the subsequent description, and the appended claims, taken in conjunction with the accompanying drawings.
The invention will now be described with reference to the drawings, wherein like numerals in different drawing figures indicate like elements.
Contacting an outside surface of the first and second upright portion 26 of the base member 18, 20 are a first and second power arm or bar member 30, 32. The power arm or bar member 30, 32 is flat and straight along its edge, such that no bends or offsets occur on the bar 30, 32. The bar member 30, 32 includes a first and second orifice 34, 36 and also includes a notch or knob 38 along one surface thereof. On one end of the bar member 30, 32 is a second knob 40 which is used to secure a holder member on the clamp 16. The first and second bar members 30, 32 are pivotally connected to the up right portion 26 of the base members 18, 20 on opposite sides of the base members 18, 20 such that the first and second base members 18, 20 are disposed between the first and second bar members 30, 32. The bar members 30, 32 are connected, via a rivet 42 to the first and second base member 18, 20 at the first orifice 34 of the bar member 30, 32. It should be noted that any other type of fastener may also be used to connect the bar members 30, 32 to the base members 18, 20 such as but not limited to a pole, pin, dowel, screw, or any other known fastener may also be used. The bar member 30, 32 is arranged and connected to the base member 18, 20 such that the notch 38 faces in the direction opposite of the base member 18, 20 when the clamp 16 is in the fully engaged or closed position.
Link members 44, 46 as shown in
The clamp 16 includes first and second handle members 60, 62. The first and second handle members 60, 62 are pivotally connected to the base members 18, 20 via a first orifice 64 in the handle 60, 62. The handle member 60, 62 generally has a body portion 66 and an arm 68 extending from the body portion 66. The body portion 66 and the arm 68 intersect at an off set or bend in the handle member 60, 62. The handle member 60, 62 is the only part of the clamp 16 that includes an off set or bend, within all of the moving parts of the clamp mechanism. The link members 44, 46 and the bar members 30, 32 are straight and therefore increase the strength of the clamp 16, on the order of 30 to 40 percent over prior art clamps. The handle members 60, 62 include the off set such that all moving parts of the clamp 16 are located within the first and second handle members 60, 62, and therefore prevent any pinch points from interacting with the user of the clamp. The handle members 60, 62 are pivotally connected to the base members 18, 20 such that the arms 68 of the first and second handle members 60, 62 contact each other and have a grip 70 made out of a plastic, rubber, cloth or like material, fixed over the ends of the two handle members. The handle members 60, 62 also pivotally connect, via its second orifice 72, to the second orifice 52 of the link member 44, 46. The connection is made via a fastener, preferably a rivet, however it should be noted that any other type of pole, pin, screw, nail, etc., may also be used, that includes a bushing surrounding the rivet. The pivot connection of the handle member 60, 62 to the base member 18, 20 is secured by a fastener. In one embodiment that fastener is a rivet and a bushing, however any other type of fastener, such as a screw, pole, dowel, pin, nail, etc., may also be used.
The first and second handle members 60, 62 also include a leg member 74 which extends from a surface of the body 66. The leg member 74 contacts the flange of the first and second base member 18, 20 when the clamp 16 is in the open/disengaged position. When the leg member 74 is in contact with the base member 18, 20 the arm 68 of the handle 60, 62 is a predetermined angle from the base member 18, 20. This angle provides for increased clearance for the hands and fingers of the operator of the clamp 16. In the preferred embodiment the angle is approximately 30°, however it should be noted that any angle from 10° to 85° may be designed into the clamp 16. The handle member 60, 62 is positioned such that an inside surface of the first and second handle members 60, 62 are adjacent to an outside surface of the first and second bar members 30, 32. The handle members 60, 62 are arranged such that the first and second bar members 30, 32 and the first and second base members 18, 20 along with the first and second link members 44, 46 are all disposed between the first and second handle members 60, 62 within a space provided by the offset of the first and second handle members 60, 62. It should be noted that the first and second handle members 60, 62 are the only members of the clamp 16 to have a specific left hand and right hand part. All other parts of the clamp 16 including the base members 18, 20 are interchangeable and therefore reduce the number of different parts that have to be stamped in assembling a predefined number of clamps. It should further be noted that the link members 44, 46, the bar members 30, 32 and the handle members 60, 62, all may be combined into a single unitary part for each of the above referenced members. Hence, the first and second handle members 60, 62 would become one single piece, the first and second bar members 30, 32 would become one single piece, the first and second link members 44, 46 would become one single piece, etc.
As shown in
A spring 94 is arranged around the fastener that secures the lever 80 to the handle members 60, 62. The spring 94 is a torque spring. However, it should be noted that any other type of known spring may be used for the present invention. The torque spring 94 will have a predetermined number of coils that have a predetermined inner diameter that is capable of being arranged around the rivet or fastener. The spring 94 has a first and second arm 96, 98 extending from the coils thereof. The first and second arms 96, 98 of the torque spring 94 each have a finger 100 extending from an end thereof. One of the torque spring fingers 100 will be in contact with a surface of the handle members 60, 62. The other of the torque spring fingers 100 will be in contact with a surface of the lever 80. The torque spring 94 will urge, via its spring force, the locking lever 80 away from the handle members 60, 62. This will ensure that the locking tab 82 or the locking lever 80 will stay fully engaged with the locking shoulder 58 of the link members 44, 46. When an operator of the clamp 16 squeezes or rotates the locking lever 80 in the direction of the handle members 60, 62 this will compress the spring 94 and allow for the engaged locking tab 82 to disengage from the locking shoulder 58 of the link members 44, 46 thus allowing for the clamp 16 to be opened/disengaged from the object being held. It should be noted that in one embodiment the spring 94 is made of a metal material preferably steel, however any other known metal, ceramic, plastic or composite material may be used for the torque spring 94. It should also be noted that it is contemplated to have the torque spring 94 arranged on an inner surface of the flange of the lever 80, thus having the spring 94 arranged within the clamp 16 to avoid snagging or other damage thereto in the manufacturing environment. It should also be noted that any size coil, arms, and fingers may be used on the torque spring 94. It should be noted that any size or shape may be used for the extension 92 on the locking lever 80 and that the embodiment shown uses the curved surface for ergonomic purposes.
As shown in
In operation the clamp 16 is in an open position when the handle member 60, 62 is pulled fully open and the leg 74 rests on the flange 24 of the base member 18, 20. The handle member 60, 62 is designed such that the arm 68 of the handle member 60, 62 has a predetermined angle from the base member 18, 20 such that there is an increase in clearance from the hands and fingers of the operator. It should further be noted that an increase of clearance occurs between the arm 68 of the handle 60, 62 and the bar member 30, 32 which extends in an up right position when the clamp 16 is in the fully open position. This provides for increased clearance such that the knuckles and fingers of the operator are not engaged with the bar member 30, 32 when operating the clamp 16.
When an operator wants to secure the part being clamped the operator will move the handle member 60, 62 into a vertical position from its open/fully disengaged position into a closed/fully engaged position such that the handle 60, 62 is placed into a nearly upright position. This will in turn allow the locking tab 82 of the locking lever 80 to slide along the link members 44, 46 until the locking tab 82 engages and is secured with one of the locking shoulders 58 of the link members 44, 46. The clamp 16 secures the work piece by having an over center position between the power arm 30, link member 44 and handle members 60 such that an over center force is created. This over center force amplifies the force and holding power of the clamp 16. The over center point is engaged when the buttons or stoppers 54 engage with the notch 38 of the bar members 30 to create the over center or high force position for the clamp 16. This force is created by the link members 44, 46 rotating with respect to the handle member 60, 62 and bar member 30, 32. The notch 38 and over center buttons 54 merely define the over center position which creates the greatest force capable by the toggle link of the clamp 16. The locking tab 82 and locking mechanism will then ensure that the clamp 16 stays in the over center position thus allowing for the clamp 16 to operate at its greatest force capable without disengagement by vibrations or other environmental conditions of the manufacturing environment.
It should be noted that the use of an over center button 54 that is punched or formed into the metal is preferred over the prior art use of welding a pin or other device as an over center stop in clamps. This provides for a more reliable over center point thus increasing the strength and durability of the clamp 16. With regards to the interchangeability of all clamps members, excluding the first and second handle members, the use of the members with a straight or linear parts also increases the strength. Any where a bend or offset is located in prior art clamps created stresses and weakens the clamp, thus reducing the overall life of the clamp. The clamp according to the present invention uses all straight or linear parts. The use of the straight or linear members for the link and bar members increases the strength of the clamp by approximately 30 to 50 percent over prior art clamps thus increasing the life and serviceability of clamps in the field. Furthermore the inclusion of a locking lever 80 and locking shoulder on the link members increases the reliability and cost effectiveness of the clamp in the manufacturing environment.
The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.
Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3924844 | Bachtel, Jr. | Dec 1975 | A |
| 5527024 | Dysktra | Jun 1996 | A |
| 5961109 | Dykstra et al. | Oct 1999 | A |
| 6595507 | Dykstra | Jul 2003 | B2 |
| 6817603 | Kofod | Nov 2004 | B2 |
