Supports – Pipe or cable – Brackets
Reexamination Certificate
1999-04-26
2001-02-27
King, Anita M. (Department: 3632)
Supports
Pipe or cable
Brackets
C248S074400
Reexamination Certificate
active
06193195
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to the field of devices used to secure metal tubing, and in particular thin-walled metal tubing, during end forming operations such as flaring, beading, upsizing and downsizing. More particularly, the invention relates to such devices which involve a clamping bar having one or more tube receiving bores, where the bar is divided into two members on a plane passing through the bore axis or axes, so that the bar halves may be separated for insertion of a metal tube into the bore. The two bar halves are then pressed together to tightly clamp the metal tube to prevent movement of the tube relative to the clamp in the axial direction.
There are numerous cold-forming operations which must be performed on relatively thin-walled metal tubes in order to provide a tube having a properly configured end segment for a particular application. Thin-walled tubes of aluminum, steel, or equivalent metals or alloys are well known and are used in thousands of different applications where a specific end configuration is required, such as to join the tubes to fittings or other components in an equipment fluid line. The tubes are created by taking a stock tube having a constant outer and inner diameter and altering the end of the tube by pressing a die onto the tube end in the axial direction, the die deforming the metal into the desired configuration. For example, the tube end may need to be flared into a conical or bell-shaped configuration, or an annular bead may need to be created about its circumference, or the tube end may need to be downsized or upsized. Because the force is applied in the axial direction, typically by a hydraulic press, and must be sufficient to deform the metal of the tube wall into the desired shape, the tube must be securely clamped to prevent movement of the tube in the axial direction. At the same time, because the tube is thin-walled, the clamping device must prevent any bending, folding or crimping during the cold forming operation.
A known clamping device for securing thin-walled metal tubes to prevent movement in the axial direction during cold forming operations comprises a base member and a removable clamping member, each having a mating surface having a substantially semi-circular channel cut therein, such that when the base and top members are joined the channels align to define a generally circular bore to receive the metal tube. A tube having an outer radius matching or slightly exceeding the channel radii is placed into the semi-circular channel of the base member with its end extending a short distance beyond the forward edge of the base member, and the semi-circular channel of the top member is positioned to encompass the tube. Force is then applied to the base and top member, thereby securely clamping the tube between the base and top members. The width of the base and top members in the axial direction must be sufficient to provide enough frictional resistance to secure the tube against the axial pressures encountered in the cold forming operation.
To improve the gripping ability of such clamps, it is known to provide the semi-circular channels with annular grooves in the plane perpendicular to the central axis by removing material to form V-shaped, U-shaped or rectilinearly walled grooves at spaced intervals along the main axis. When the top and base members are clamped together, the grooves allow the clamping device to grip the tube more securely than if the walls were smooth.
It is an object of this invention to provide for an improved clamping device for thin-walled metal tubes which precludes movement in the axial direction when cold forming pressure is applied against the tube end by providing annular grooves which are cold formed into the walls of the semi-circular channels rather being formed by a cutting or material-removing operation, such that each groove comprises a pair of raised shoulders which extend slightly out of the channel wall. The raised shoulders more securely grip the outer wall of the tube to create greater resistance to movement in the axial direction, allowing for a reduction in dimension for the clamp in the axial direction and allowing for application in the radial direction of a smaller clamping force against the tube itself. It is a further to provide such a clamping device wherein a simple cam mechanism is used to provide the clamping pressure so that the clamping operation can be performed easily and quickly without the need for securing and releasing threaded bolts. These and other objects not expressed in this section will be achieved by and apparent from the disclosure which follows.
SUMMARY OF THE INVENTION
The invention comprises in general a clamping device for securing thin-walled metal tubes to preclude axial movement when the end of the tube is being cold formed to alter its shape, and is particularly designed to restrain the tube against force directed against the tube end in the axial direction. The clamping device has two major components, a base member and a clamping member, each having a mating surface with at least one tube receiving channel, and preferably multiple tube receiving channels of different sizes positioned laterally so that one clamping device is operative for a plural number of particular tube outer diameters, whereby the tube to be secured is encircled by a bore defined by the paired tube receiving channels of the base and clamping members when the mating surfaces are properly positioned facing each other. Force application means to compress the base and clamping members together is provided to securely grip the tube within the bore. The forward portion of each of the tube receiving channels at the front wall may be provided with forming portions of various configurations so as to impart a desired configuration to the tube end when a cold forming die is coaxially advanced against the tube end by hydraulic or other powered means. The rear wall of the base and clamping members is abutted against a backstop member of the cold forming equipment, or the clamping device may be secured to a fixed component of the cold forming equipment, to preclude movement of the device during the cold forming operation.
The tube receiving channels, which are generally semi-circular in shape, are provided with a plural number of axially-spaced, annular grooves to better grip the outer walls of the tube. The grooves are preferably created by cold forming techniques, as opposed to machining or cutting techniques, such that each groove comprises a recess extending into the channel wall and a pair of raised edges or shoulders extending a relatively short distance out from the channel wall, the shoulders being formed from material shifted from the area of the recess. The raised shoulders bite into the outer wall of the metal tube when the base and clamping members are pressed together, thereby securing the tube against axial movement.
In a simple embodiment, the force application means may comprise threaded bolts which extend through the base and clamping members, such that the base and clamping members are pressed together by turning the bolts. In a preferred embodiment, the force application means comprises a cam mechanism having a bracket which encircles the base and clamping members. A handled lever is pivotally mounted to the bracket in a manner whereby pivoting the lever moves a roller member from a recessed position to an abutting position against the clamping member, thereby pressing the clamping member against the base member and securing the tube within the tube receiving bore.
REFERENCES:
patent: 1834404 (1931-12-01), Koch
patent: 2338660 (1944-01-01), Morehouse
patent: 2354919 (1944-08-01), Lockwood
patent: 2355742 (1944-08-01), Morehouse
patent: 2361943 (1944-11-01), Issoglio et al.
patent: 3592427 (1971-07-01), Misuraca
patent: 4037810 (1977-07-01), Pate
patent: 4744535 (1988-05-01), Patenaude
patent: 4919372 (1990-04-01), Twist et al.
patent: 5060810 (1991-10-01), Jones
patent: 5160105 (1992-11-01), Miller
patent: 5794897 (1998-08-01), Jobin et
King Anita M.
Saitta Thomas C.
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