Work holders – Relatively movable jaws – Means to actuate jaw
Reexamination Certificate
2000-06-30
2001-10-02
Hail, III, Joseph J. (Department: 3723)
Work holders
Relatively movable jaws
Means to actuate jaw
C269S172000, C269S182000
Reexamination Certificate
active
06296241
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to C-clamps and more particularly, to an adjustable C-clamp which is characterized by a generally C-shaped clamp frame having a top frame segment, an intermediate frame segment and a bottom frame segment, which top and bottom frame segments are fitted with top and bottom clamp seats, respectively. A clamp cylinder is threaded in the top clamp seat substantially parallel to the intermediate frame segment. The clamp cylinder slidably receives a slotted cylinder which is secured in place typically by means of an alien screw, fitted in an allen screw receptacle approximately one-half of which extends through the clamp cylinder and the other half through the slotted cylinder. The slotted cylinder is characterized by a pair of parallel, diametrically-opposed longitudinal cylinder slots each of which communicates with a corresponding set of multiple, vertically spaced-apart, peripheral pin slots. A clamp rod is slidably extended through the bore of the slotted cylinder and is fitted with a pin opening for receiving a clamp rod pin. A clamp nut fitted to the extending end of the clamp rod faces the bottom clamp seat of the clamp frame. Manipulation of a clamp rod grip provided on the opposite end of the clamp rod from the clamp nut facilitates slidably adjustment of the clamp rod inside the slotted cylinder and the clamp cylinder as the clamp rod pin traverses the parallel longitudinal cylinder slots to align with a selected pair of pin slots. Twisting of the clamp rod typically in the clockwise direction as viewed from the clamp rod grip end facilitates movement of respective ends of the clamp rod pin into the pin slots and engagement of the clamp rod pin with the slotted cylinder. Accordingly, the clamp nut can be quickly positioned at a selected spacing from the bottom clamp seat to accommodate a workstock of selected width and thickness between the clamp nut and bottom clamp seat. Continued clockwise rotation of the clamp rod in the slotted cylinder facilitates threaded extension of the clamp cylinder through the top clamp seat of the clamp frame and incremental advancement of the clamp nut against the workstock to secure the workstock between the clamp nut and the bottom clamp seat. In another embodiment, the slotted cylinder is omitted and the longitudinal cylinder slots and respective sets of pin slots are milled, casted or otherwise provided in the bore wall of the clamp cylinder.
One of the problems inherent in conventional C-clamps is the frequent requirement that the threaded rod element be adjusted through the full range of threads in order to accommodate a fairly thick workstock and then adjusted through the same range of movement to accommodate a relatively thin workstock. There is no facility in the conventional C-clamp for quickly effecting an adjustment between a thin workstock and a thick workstock, and vice-versa.
C-clamps are extremely useful tools for various purposes in wood and metal work as they are quite easily used to clamp workstock of varying thicknesses to a workbench, work table or other fixed object and are commonly used for a variety of other purposes. However, the time and effort required to adjust from the thin workstock to the thick workstock and vice-versa, is objectionable and there exists a need in the art for an adjustable C-clamp for quickly and easily effecting this adjustment.
DESCRIPTION OF THE PRIOR ART
One of the adjustable C-clamps known in the art is the “Pressure Unit”, detailed in U.S. Pat. No. 2,755,681, dated Jul. 24, 1956, to Merriman. The clamp is characterized by a bushing threaded in the bottom frame member of a C-shaped clamp frame. A clamp rod which is terminated by a pressure foot for engaging a workstock and fitted with multiple teeth is slidably mounted in the bushing. The clamp rod can be slidably extended through the bushing to locate the pressure foot a selected spacing from the top frame member of the clamp frame, and locked in place by inserting a detent in the bushing and between a pair of teeth on the clamp rod. Subsequent rotation of the clamp rod in the bushing threads the bushing through the bottom frame member and gradually advances the pressure foot toward the top frame member. Another adjustable C-clamp is the “Quick Acting C-Clamp” described in U.S. Pat. No. 2,812,789, dated Nov. 12, 1957, to Hutson. The Hutson clamp is characterized by a C-shaped frame having an elongated sleeve which is slidably extendible through one of the parallel frame members of the frame. A threaded shaft terminated by a clamp head for engaging a workstock extends through the sleeve. The sleeve can be adjusted to accommodate a workstock of selected thickness by sliding the sleeve through the frame member and then engaging pawls on the frame with ratchet teeth on the sleeve. The threaded shaft is then rotated to gradually extend the shaft from the sleeve and the clamp head against the workstock. U.S. Pat. No. 3,245,676, dated Apr. 12, 1966, to Floren, et al., discloses a “Quick Acting Plastic Service T Clamp” having a C-shaped frame fitted with an interiorly-threaded sleeve adjustably mounted in one of the parallel frame members at one end of the frame by means of a set screw. A rod fitted with a workstock-engaging member is provided with a threaded collar which engages the interior threads of the sleeve. The workstock engaging member is adjusted with respect to the workstock by sliding the rod and sleeve through the frame member and securing the sleeve at the desired position in the frame member by means of the set screw. The engaging member is then gradually advanced toward the workstock by rotating the rod and threaded collar in the threaded sleeve. A “Screw Clamp” is disclosed in U.S. Pat. No. 3,403,901, dated Oct. 1, 1968, to Servadio. The screw clamp includes a C-shaped frame, a clamping jaw fitted on a first leg and a shaft screw provided on the facing parallel second leg of the frame. A sleeve provided with a slot for accommodating the second leg of the frame is slidably mounted on the shaft screw and a handle screw is threaded on the shaft screw for slidably advancing the sleeve on the shaft screw and toward the workstock. U.S. Pat. No. 3,704,014, dated Nov. 28, 1972, to Keene, describes a “Quick-Adusting C-Clamp” having a C-shaped frame including a pair of arms at respective ends thereof, one of the arms having a stationary clamp jaw. The other arm is provided with a shaft seat and an elongated slot for accommodating a threaded screw terminated by a movable clamp jaw. A nut is threaded on the middle portion of the screw and disengages the shaft seat as a workstock is positioned between the movable and stationary clamp jaws. The shaft is extended through the elongated slot toward the workstock, the nut is seated in the shaft seat and the shaft is rotated in the nut to gradually advance the movable clamp jaw toward the workstock. A “Terminal Clamp” is disclosed in U.S. Pat. No. 4,083,624, dated Apr. 11, 1978, to Timmer. A bearing pad is provided at one end portion of a C-shaped clamp frame, and a tubular member which slidably receives a clamping rod is threadibly mounted in the other end portion of the clamp frame. A one-way rotatable interlock is provided between the clamping rod to induce movement of the tubular member toward the bearing pad. A brake is provided for restraining rotation between the tubular member and the frame. U.S. Pat. No. 4,627,604, dated Dec. 9, 1986, to Choi, describes an “Adjustable Clamp” characterized by a C-shaped frame having a first frame segment fitted with multiple ratchet teeth and a second frame segment provided with a clamp jaw and provided with a handle-operated ratchet for engaging the ratchet teeth and advancing the second frame segment on the first frame segment. A rod provided with a handle and terminated by a movable clamp jaw threadibly engages the first rod segment, and fine adjustment of the movable clamp jaw with respect to the fixed clamp jaw is effected by rotation of the handle. Gross adjustment of the clamp j
Hail III Joseph J.
Harrison John M
Shanley Daniel
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