Cast refiner plate segment with blunt edges and corners for safe handling

Abstract

A cast metal plate segment for a refiner of lignocellulosic material or a disperser of comminuted paper or packaging products, the plate segment including a front side with a front surface configured to refine the lignocellulosic material or disperge the comminuted paper or packaging products, and a back side, opposite to the front side, including a corner or edge, wherein the corner or edge comprises a casted surface between machined planar surfaces adjacent the corner or edge.

Claims

1. A refiner plate segment configured to produce pulp by refining lignocellulosic material, the refiner plate segment comprising: a front side having a surface configured to refine the lignocellulosic material; and a back side having a cast blunt surface at a junction between a first machined surface and a second machined surface, wherein the first machined surface is substantially perpendicular to the second machined surface.

2. The refiner plate segment of claim 1, wherein the cast blunt surface is a cast chamfer surface.

3. The refiner plate segment of claim 2, wherein the cast blunt surface extends along a perimeter on the hack side of the refiner plate segment and the first machined surface forms the perimeter on the back side of the refiner plate segment.

4. The refiner plate segment of claim 2, wherein the cast blunt surface is on a body junction, and wherein the first machined surface and the second machined surface are surfaces of a rib.

5. The refiner plate segment of claim 1, wherein the cast blunt surface is a cast rounded surface.

6. The refiner plate segment of claim 5, wherein the cast blunt surface is on an outer junction and wherein the first machined surface is at a perimeter of the refiner plate segment.

7. The refiner plate segment of claim 5, wherein the cast blunt surface is on a body junction and the first machined surface and the second machined surface are surfaces of a rib.

8. The refiner plate segment of claim 1, wherein the cast blunt surface is at least one of a cast chamfer surface and a cast rounded surface.

9. The refiner plate segment of claim 1, wherein the cast blunt surface is on a perimeter rib of the refiner plate segment and wherein the first machined surface and the second machined surface are surfaces of the perimeter rib.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a conventional large rib with flat machined surfaces of a refiner plate segment.

(2) FIG. 2 shows an exemplary large rib with a chamfer surface of a novel refiner plate segment.

(3) FIG. 3 shows an exemplary large rib with a rounded surface of a refiner plate segment.

(4) FIG. 4 shows an exemplary back side of a refiner plate segment with chamfer surfaces used throughout the back side of the refiner plate segment.

(5) FIG. 4a shows the detail in the circle shown in FIG. 4 of an exemplary refiner plate segment back side where casted chamfer surfaces are used on the junctions on the back side of the refiner segment.

(6) FIG. 5 depicts an exemplary casting mold for a refiner plate segment having rounded blunt surfaces at portions of the casting mold that can form outer junctions of the back side of the refiner plate segment.

DETAILED DESCRIPTION OF THE INVENTION

(7) The foregoing will be apparent from the following more particular description of example embodiments of the disclosure, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating embodiments of the disclosed device.

(8) It is desirable to provide a refiner or disperser plate segment with cast blunt surfaces, especially the back side of the refiner plate segment, to reduce the hazardous sharp edges and corners created when the cast refiner plate segment is precision machined.

(9) FIG. 1 shows a rib 100 with flat machined surfaces, as currently produced when the cast refiner plate segment is precision machined. The rib 100 has bars 111 and grooves 112 at the bottom. These bars 111 and grooves 112 are found on the working surface of the refiner plate segment. In current refiner plate segments, the underside of the segment may have sharp, square edges and corners, wherein the edges and corners are collectively referred to as junctions. The cast top surface 140 (shown by the dotted lines) and the cast side surface 130 (shown by the dotted lines) intersect to form the cast sharp, square edge 151.

(10) Once cast, the refiner plate segment can be precision machined. During machining, approximately 1 mm of material is ground from the cast surfaces to produce flat metal surfaces, such as a machined top surface 110 and machined side surface 120. The junctions between intersecting metal surfaces form sharp machined metal-to-metal junctions. Junction 150 is an example of a sharp edged junction formed by the intersection of machined top surface 110 and machined edge surface 120. These sharp machined metal-to-metal junctions 150 have been and continue to be the source of injuries to personnel handling the refiner plate segments.

(11) FIG. 2 shows an exemplary embodiment where the cast blunt surface is a cast chamfer surface 225. A rib 200 is depicted with a cast chamfer surface 225 along the edge of the rib 200. The rib 200 has bars 211 and grooves 212 at the bottom. As with the bars 111 and grooves 112 of FIG. 1, these bars 211 and grooves 212 can be found on the working surface of the refiner plate segment. The cast top surface 240 (shown by the dotted lines), the cast side surface 230 (shown by the dotted lines) and a diagonal cast surface 226 (shown by dotted lines) intersect. The diagonal cast surface 226 may be sized to be large enough so the precision machining of the cast refiner plate segment results in a cast chamfer surface 225 forming an angle with the horizontal cast top surface 240, the angle being between 105 degrees and 165 degrees, desirably 120 degrees to 150 degrees.

(12) Once cast, the refiner plate segment may be precision machined. Approximately 1 mm of material can be ground from the cast top surface 240 and the cast side surface 230, to produce a machined top surface 210 and a machined side surface 220. The diagonal cast surface 226 is large enough not to be fully removed by machining the cast top surface 240 and cast side surface 230. After machining, a portion of the diagonal cast surface that remains. The remaining portion of the diagonal cast surface is the cast chamfer surface 225. The cast chamfer surface 225 is between the machined top surface 210 and machined side surface 220. Because of the cast chamfer surface 225, the precision machining of the machined top surface 210 and machined side surface 203 does not form sharp edges and corners. The cast chamfer surface 225 generally does not cut the hands of persons handling the plate segments.

(13) The precision machining of the rib 200 can be accomplished to allow multiple cast chamfer surfaces 225. For example, cast chamfer surfaces may be machined on each side of the rib 200. In an alternative embodiment, only one cast chamfer surface 225 may be produced on one side of the rib 200.

(14) FIG. 3 shows an exemplary embodiment in which the cast blunt surface is a cast rounded surface. This figure depicts a rib 300 with a cast rounded surface 325 along the rib 300. The rib 300 has bars 311 and grooves 312 at the bottom. As with the bars 111 and grooves 112 of FIG. 1, these bars 311 and grooves 312 can be found on the working surface of the refiner plate segment. The cast top surface 340 (shown by the dotted lines), the cast side surface 330 (shown by the dotted lines), and a rounded cast surface 326 (shown by dotted lines) intersect. The rounded cast surface 326 is sized to have a radius of curvature sufficiently long to ensure that the machining of the cast top surface 340 and the cast side surface 330 do not fully remove the rounded cast surface 326. The portion of the rounded cast surface 326 that remains after machining is the cast rounded surface 325.

(15) During precision machining, approximately 1 mm of material is ground from the cast top surface 340 to produce the machined top surface 310 and approximately 1 mm of material can be removed from the cast side surface 330 to produce the machined side surface 320. Because the cast rounded surface 325 is not fully removed by the precision machining, sharp edges and corners are generally not formed by the intersection of the machined top surface 310 and the machined side surface 320.

(16) The precision machining of the rib 300 can be accomplished to allow multiple cast rounded surfaces 325 (on each side of the large rib 300) as shown. In another exemplary embodiment, only one cast rounded surface 325 may be produced.

(17) FIG. 4 shows the back side of an exemplary refiner plate segment 400 with cast chamfer surfaces 425 used throughout the back side of the refiner plate segment 400. Cast chamfer surfaces 425 can be used on the outer junctions 425a and body junctions 425b of the refiner plate segment back side. Although this exemplary embodiment depicts chamfer surfaces 425 used throughout most ribs 401 on the back side of the refiner plate segment 400, in other embodiments chamfer surfaces 425 may be used mostly on select ribs 401 such as the perimeter ribs 402.

(18) FIG. 4a shows the detail x of FIG. 4. FIG. 4a depicts the back side of an exemplary refiner plate segment 400. In exemplary embodiments, the cast chamfer surfaces 425 can be between machined surfaces (see 210 and 220 of FIG. 2) that are substantially orthogonal to machined surfaces.

(19) FIG. 5 depicts an exemplary casting mold 500 in which blunt surfaces are chamfer blunt surfaces 515. In other exemplary embodiments, the blunt surfaces may be rounded blunt surfaces. The casting mold may be a positive mold of the final refiner plate segment. Sand or other such suitable material is generally poured into the casting mold 500 and sealed to form a sand mold (not pictured) that is a negative mold of the refiner plate segment. Molten metal is generally poured into this mold to create the cast refiner plate segment (see FIG. 4). The chamfer blunt surfaces 515 are at portions of the casting mold that would otherwise form a junction between machined metal surfaces on the refiner plate. These junctions may be formed by substantially orthogonal machined surfaces (see 210 and 220 of FIG. 2). In other exemplary embodiments, these junctions may be formed by machined surfaces that form acute or obtuse angles relative to adjacent machined surfaces.

(20) While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.