Refining plate attached to a head in a pulp refiner

A refiner plate has an outer circumferential edge, a front surface having comminuting projections, and a rear surface. The refiner plate also has and a single mounting opening radially inward from the outer circumferential edge. The refiner plate also includes a radially extending key attached to the rear surface, the key having an end forming a tab that extends past the plate outer circumferential edge.

BACKGROUND OF THE INVENTION

This invention is directed to pulp refiners, and, more particularly, to the mechanism used for attaching a refining plate to its supporting head.

Some refiners for wood pulp or the like, have stationary refining plates that flank rotary refining plates in the chamber of a housing whose inlet admits stock for treatment by comminuting projections (e.g., ribs) on the neighboring surfaces of stationary refining plates and rotary refining plates. Currently, the set of refining plates that are mounted to the rotating and stationary heads use four or more fasteners for each refiner plate. Mounting holes are normally located in the refining area of the plates, thus reducing the useful refining surface. The plates fit against an outer ring at the outside diameter of the head. The outer ring contains the plates in proper location and prevents outward movement due to centrifugal forces. The fasteners are designed to carry all the torsional forces acting on the refiner plates that occur during operation, while the outer ring carries all the centrifugal forces. In setting the plates against the outer ring, the plates are equally spaced around the head in the circumferential direction, with minimal space between each plate. However, due to manufacturing tolerances, openings can be created between the plates, and these openings can result in corrosive or erosive attack on the head mounting surfaces. Installing or replacing plates is very time consuming, and is dependent on the number of fasteners that need to be removed or installed.

SUMMARY OF THE INVENTION

The refiner plate of this invention is designed with a radial key that is attached to the plate's rear mounting surface. This radial key carries all torsional forces that act on the plates. At the outer end of the key, a tab is used to attach the plate to its supporting head. The plates are butted against a lip or ring on the outer circumference of the supporting plate, so that the ring carries all centrifugal forces. Near the inner end of the key, a fastener is installed in an opening passing through the plate and its supporting head. The combination of the fastener and the tab are used to hold the refiner plates in position. The fasteners and tabs are only used to locate the plates. They do not carry any radial or circumferential loads.

The fasteners are located outside the refining area of the plates, resulting in a significant increase in refining surface. Since there is only two fasteners per plate, the time to install and/or replace plates is significantly reduced. The plates are manufactured to tight tolerances, so that when a set of plates is installed, each plate is angled into position without requiring any radial movement. This helps to insure that minimal gap occur between the plates. The tight tolerances increase the cost of the refiner plates, but the savings realized due to fewer holes in the plates and fewer tapped holes in the heads, as well as savings in assembly and disassembly, more than offset the increased costs.

More particularly, the invention comprises a refiner plate having an outer circumferential edge, a front surface having comminuting projections, and a rear surface. The refiner plate also has a mounting opening radially inward from the outer circumferential edge. The refiner plate also includes a radially extending key attached to the rear surface, the key having an end forming a tab that extends past the plate outer circumferential edge.

Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of the construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. Further, it is to be understood that such terms as “forward”, “rearward”, “left”, “right”, “upward” and “downward”, etc., are words of convenience in reference to the drawings and are not to be construed as limiting terms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As illustrated inFIG. 1, the invention provides a disc refiner having a housing10including several bolted-together sections, two of which are shown at12and14. The housing defines a stock chamber16and has an inlet18for admission of pulp, a first outlet20for evacuation of the refined pulp, at least in part under the action of centrifugal force, and a second outlet22that is normally closed by a suitable valve24. The outlet20extends upwardly and the outlet22extends downwardly. The valve24is opened when the attendants wish to drain the liquid carrier for wood chips or the like from the chamber16. Although a particular housing geometry is shown, no particular housing construction is required.

The chamber16accommodates three refining members26,28, and30, here shown as coaxial discs having identical outer diameters. In other embodiments (not shown), two back-to-back discs can be used instead of the single disc28. In still other embodiments (not shown), just two refining members can be used. The disc26is stationary and is fixedly secured to the housing section12by screws (not shown) or analogous fasteners. The disc30also does not rotate. This disc is spaced apart from the disc26and is secured to an axially movable support34by means of screws (not shown) or the like. The support34is mounted in the housing section14and is movable axially of the discs26,28by a reversible electric motor38. The disc28is rotatable relative to and is movable axially between the discs26and30. The means for rotating the disc28comprises a drive shaft50that rotates in a bearing52mounted in the housing section12.

The disc26has a relatively large central opening56that communicates with the inlet18and surrounds the shaft50with a substantial amount of clearance. The end portion of the shaft50that extends beyond the opening56and into the central part of the chamber16drives the disc28in a conventional manner.

The space between the discs26and28and the space between the discs28and30, respectively, define first and second paths along which the pulp can advance from the inlet18toward the first outlet20(the second outlet22is assumed to be sealed when the refiner is in use). The first path is flanked by rib-shaped comminuting projections74,76of the discs26,28, and the second path is flanked by rib-shaped comminuting projections78,80of the discs28,30. The opening56of the disc26admits pulp from the inlet18into the central portion of the first path, and such pulp flows radially outwardly between the projections74and76toward the outlet20.

As best shown inFIG. 2, this invention provides a refining member for the refiner, the refining member, being, for example, the disc28. More particularly, the refining member28comprises a head82having a plurality of radially extending slots84(seeFIGS. 2 and 3), an outer circumferential edge86, and a mounting hole88spaced radially inwardly from the outer circumferential edge86.

The refining member28further includes, as shown inFIGS. 1 and 2, a device90outside of and attached to the head circumferential edge86and extending beyond the head outer circumferential edge in the direction of axial rotation of the head. More particularly, the devices are a plurality of retainers90(seeFIGS. 2 and 7) spaced apart around and attached to the outer circumference of the supporting head82. Although not shown inFIG. 3, which illustrates only the head82, a retainer90is attached to the head82at the end of each of the slots84.

As best seen inFIG. 7, each retainer90includes a top having a central flat and ends that slope downward away from the central flat, and a bottom92(seeFIG. 2). The flat has two spaced apart holes91, that pass through the retainer90, for receiving threaded bolts85that secure the retainer90to the outer circumference of the supporting head82. The retainer90also has two opposed sides, and an opening93that passes between the sides and through the retainer90between and perpendicular to the bolt holes91. The sides of the retainer90extend beyond the head outer circumferential edge in the direction of axial rotation of the head in both the face and rear directions.

As best shown inFIGS. 2,4,5and6, the refining member28further includes a plurality (not shown, but four, in this instance) of refiner plates100, each plate100having an outer circumferential edge104and including comminuting projections. Although the refining member28is described in detail, the discs26and30are similarly constructed (but not shown), with refiner plates100mounted on stationary heads with slots84. On the stationary discs26and30, the head outer circumferential edge is where the outer edges of the refiner plates are located.

More particularly, as shown inFIGS. 1 and 2, the head82supports refiner plates100on both the front and the rear surfaces of the head82. Although, in this embodiment, the head slots85on the rear of the head82are aligned with the slots84on the front of the head82, in other embodiments (not shown), the front slots84can be offset circumferentially from the rear slots85.

For the remainder of this description, the refiner plate100shown on the left inFIG. 2will be described in greater detail. This description is equally applicable to any of the other refiner plates.

As shown inFIGS. 2,4and6, each of the refiner plates100has a main body having a front surface108having comminuting projections76, and a rear surface112. Each refiner plate100also includes a radially extending key116fixedly attached to the plate rear surface112and received in a respective one of the plurality of head slots84and85. For example, the key116can be attached to the plate rear surface by welding, or it can be an integral part of the plate100. Each key116has an end that forms a tab120that extends past the plate outer circumferential edge104. The sides of the retainer90are notched in order to receive the tab120and to surround the head of a fastener107(seeFIG. 2) that releasably secures the tab120to the retainer90. The notched sides of the retainer90also help prevent side-to side movement of the tab120and the plate100relative to the head82.

Each plate100is held against radially outward movement by a lip or ring101(seeFIG. 3) around the outer circumference of the head82. Notches109in the lip108permit the tab120to extend past the outer circumference of the head82. In less preferred embodiments of the invention (not shown), the lip101could be omitted, and the plate outer circumferential edge104could abut the bottom of the sides of the retainer90.

A mounting opening124radially inward from the comminuting projections76in the refiner plate100is aligned with the head-mounting hole88, and a fastener128extends through the plate mounting opening124into the head-mounting hole88to removably secure the refining plate100to the head82.

The refiner plates100are thus attached to the disc head82in the following manner. The four retainers90are secured to the outer circumference of the supporting head82. Then the plates100are placed on the head82, with the keys116being placed in the head slots84. A fastener128is then used to releasably secure each plate100to the head82, and a fastener107is passed through a plate tab120on the front of the head82and into the retainer90. Similarly, a fastener128and a fastener105are used to attach a refiner plate100to the rear of the head82.

Various other features and advantages of the invention will be apparent from the following claims.