Tubular core assemblies for rolls of paper or other sheet material

A stand-alone lug of non-isotropic polymeric or cellulosic material for installation in a recess in a core member of paperboard material for a roll of paper or other sheet material. The lug has a width in the range of from about 0.25 to about 4 inches, a length in the range of from about 0.5 to about 4 inches, and a thickness in the range of from about 0.25 to about 1 inch. The lug also having at least one radially inner surface, the total circumferential width of the inner surface or surfaces being at least about 0.2 inches. The lug may have a recess extending from one end for receiving a key on a stub-chuck. Where the lug is to be used with splined stub-chucks, the lug may have no recess.

FIELD OF INVENTION

This invention relates to tubular core assemblies for rolls of paper or other sheet material.

BACKGROUND OF INVENTION

After manufacture, paper such as newsprint paper is conventionally wound on hollow cylindrical core members of paperboard material which, for winding paper thereon to form a roll and unwinding paper therefrom, are mounted on winding or unwinding equipment which has a pair of spaced stub-chucks which engage in opposite ends of a tubular core member. To prevent the core member itself from being damaged by the stub-chucks, it is also conventional to provide the ends of the tubular core members with some kind of reinforcement. A common type of reinforcement comprises a tubular cap member of sheet metal with a U-shaped section which fits over an end of the core member such that an inner annular wall of the cap member engages the inner wall of the core member and an outer annular wall of the cap member engages the outer wall of the core member.

Particular problems arise when paper is being unwound from a roll and fed to a printing press. To maintain a desired tension in the paper being fed to a printing press, it is necessary to provide means to apply a braking force to the roll. This is usually done by providing a braking force to one of the stub-chucks which transmits the braking force to the core member. At least one stub-chuck at an unwinding station may be provided with one or more keys which engage in one or more notches in an end of the core member and/or cap member or may be provided with axially extending splines which engage the inner surface of a core member which has no end reinforcement.

Unfortunately, a metal cap member being isotropic will assist in transmitting cyclical shocks from a stub-chuck and chuck key to an unwinding paper web, especially after chuck wear has occurred with resultant deterioration in the quality of printing on the paper web. Also, splines on a braking stub shaft tend to damage the inner surface of the core member, with resultant loss of proper braking control and resultant deterioration of print quality.

It is therefore an object of this invention to provide a tubular core assembly which at least substantially overcomes these problems.

SUMMARY OF INVENTION

According to the present invention, a tubular core assembly for a roll of paper or other sheet material has a hollow cylindrical core member formed of paperboard material, said core member having a recess extending axially inwardly from an end thereof and radially outwardly from an inner surface thereof at least partway to an outer surface thereof, and a stand-alone lug of non-isotropic polymeric or cellulosic material fitted in the core member recess, the core member having an outer diameter in the range of from about 3 to about 14 inches and an inner diameter in the range of from about 2 to about 13 inches, the core member recess and the lug each having a circumferential width in the range of from about 0.25 to about 4 inches, an axial length in the range of from about 0.5 to about 4 inches, and a radial thickness in the range of from about 0.25 to about 1 inch, and the lug having at least one radially inner surface, the total circumferential width of the inner surface or surfaces of the lug being at least about 0.2 inches, preferably at least about 0.4 inches.

The lug may have a recess for receiving a key on a stub-chuck, said lug recess extending axially inwardly from an end of the lug adjacent said end of the core member. The lug recess may extend radially outwardly from an inner surface of the lug only partway to an outer surface thereof, whereby the lug has a roof portion over the recess. The lug recess may extend axially inwardly from said end of the lug less than halfway along the length of the lug. The core member recess and the lug recess may be rectangular in plan view. The lug recess may have a circumferential width in the range of from about 0.125 to about 3 inches and an axial length in the range of from about 0.25 to about 3.75 inches.

Alternatively, the lug may have an unrecessed lower surface extending for the circumferential width thereof for engagement by splines on a stub-chuck.

The lug may have an axially extending spline projecting from at least one side surface and digging into a side of the core member recess to assist in positioning the lug therein. The lug may have at least one rear spline projecting therefrom and digging into a rear surface of the core member recess to assist in positioning the lug therein. The lug may have a pair of stabilizers each projecting from the bottom of a respective side wall thereof adjacent an inner surface of the core member to stabilize the lug when engaged by a stub-chuck.

The present invention also provides a stand-alone lug of non-isotropic polymeric or cellulosic material for installation in a recess in a core member of paperboard material for a roll of paper or other sheet material, said lug having a width in the range of from about 0.25 to about 4 inches, a length in the range of from about 0.5 to about 4 inches, and a thickness in the range of from about 0.25 to about 1 inch, and said lug also having at least one radially inner surface, the total circumferential width of the inner surface or surfaces being at least about 0.2 inches, preferably at least about 0.4 inches.

The inner surface or surfaces of the lug preferably engage at least about 2.25% of the periphery of the stub-chuck.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings,FIGS. 1 and 2show a tubular core assembly for a roll of paper having a hollow cylindrical core member12of paperboard material helically wound in known manner. The core member12has a recess14extending axially inwardly from an end16thereof and radially outwardly from an inner surface18partway to an outer surface20thereof.

A stand-alone lug21of non-isotropic polymeric material, for example polycarbonate material, or cellulosic material, for example molded wood, is located in the core recess14. The lug21has a recess24for receiving a key on a stub-shaft (as will be described in more detail later), the lug recess24extending axially inwardly from an end26of the lug21adjacent the end16of the core member12. The lug recess24extends radially outwardly from an inner surface28of the lug22only partway to an outer surface30thereof, whereby the lug21has a roof portion32over the recess24.

The lug recess24extends axially inwardly from the end26of the lug21slightly less than halfway along the length of the lug21so as to provide a substantial solid lug body portion34rearwardly of the recess24. The total circumferential width of the portions of the inner surface28on the opposite sides of the recess24is at least about 0.4 inches.

FIGS. 3 to 5show a lug22which also have axially extending splines40projecting from both sides thereof and at least one rear spline42projecting rearwardly therefrom which dig into the sides and rear of the core recess14to assist in positioning the lug22therein. The lug22is a friction fit in the core recess14and is also secured to the lug22by a suitable adhesive.

The lug22also has a pair of stabilizers44each projecting laterally outwardly from the bottom of a respective side wall adjacent an inner surface of the core member12to stabilize the lug22when engaged by a stub-chuck.

In one particular example of this embodiment, the core member12has an outer diameter of 4 inches, an inner diameter of 3 inches, and the core member recess14and the lug22each have a circumferential width of 1.187 inches, an axial length of 1.2 inches, and a radial thickness of 0.4 inches. The lug recess24has a circumferential width of 0.75 inches and an axial length of 0.875 inches.

FIG. 6shows one end of the tubular core assembly engaged by a stub-shaft50with a key52, the key52being engaged in the lug recess24.FIG. 7shows one end of the tubular core assembly with a lug23which is the same as the lug22except that is does not have a recess24. The tubular core assembly is engaged by a stub-chuck54with splines56, some of which engage the lower surface28of the lug22at its front end, which may be chambered as shown at29. In each case, the inner surface or surfaces of the lug22or23engage at least about 2.25% of the periphery of the stub-chuck50or54.

The advantages of the invention will now be readily apparent to a person skilled in the art from the foregoing description of a preferred embodiment. Other advantages and embodiments will also be readily apparent, the scope of the invention being defined in the appended claims.