JPS6290390A - Paper stock screening apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (7) l A cylindrical porous screening member defining a raw material inflow chamber and a passing stock receiving chamber on both sides in a closed housing, and the screening holes are opened to allow adhesion to the screening surface. Screening devices including a rotor member operating in one of the chambers to eliminate solid materials are widely used in paper mills for cleaning paper stock. Typically, the raw material or feed is transferred to an inlet chamber adjacent one end of the screening cylinder, and material rejected by the screening cylinder is collected and discharged from the opposite end.

Applicants are familiar with U.S. Pat. No. 2.Staege.
No. 347.716, Hartinda
U.S. Pat. No. 2,835,173 to Le), U.S. Pat. No. 3,849,302 to Seifert.
No. 4 and No. 4.105.543, U.S. Pat.
．． No. 155.841 and No. 4,383,918, the company manufactures and sells screens as disclosed in a series of U.S. patents. All such screens manufactured and sold by the applicant, including the construction shown in the Martinzor patent, generate alternating waves of positive and negative pressure acting on the holes of the screening cylinder. The invention is characterized by a rotor including wing bars or vanes that move close to, but not in contact with, the surface of the screening cylinder in order to prevent clogging thereof.

This technique involves changes in the shape and other configurations of the rotor blades, as well as changes in the size, shape and spacing of the holes in the screening cylinder.
This is a comprehensive examination of the detailed changes that occur during the development process. Thus, by the time of Stine's patent in the mid-1940s, steel decks with numerous cylindrical, uniformly drilled holes.
It was being built.

When this perforated flat plate is rolled into a cylinder, the rolling action naturally results in a feed inlet face (inner side) and a through stock receiving face (inner side) of the respectively produced screening cylinder.
Some compression and stretching of the inner and outer edges of the drilled holes (on the outside) occurs. This naturally results in the conical or countersunk hole highlighting the receiving (discharge) end of each cylindrical hole and reducing the possibility of clogging.

More recently, screening cylinder holes have been disclosed in Lamort U.S. Pat. No. 3,617,008.
No. 3,581, Holz, U.S. Pat.
No. 03, the aforementioned Sheetart U.S. Pat. No. 3,849,
No. 302, an elongated slot rather than a circular hole, as in the structure shown in the Czapka Sietsert patent;
Pressure screens of the type generally described above are commercially available.

In both the Ramote and Holtz patents, the slots have sides parallel to the inlet side of the cylinder, but on the receiving side each slot has wide open sidewalls.

Similarly, in the case of Čapka Seetshut, screening
The cylinder is made of wire of triangular cross section with the inlet side of the cylinder as the base of the triangle.

This highlighting of the receiving side of the holes in the screening cylinder of a pressure screen has been practiced consistently since it was first introduced in the paper industry. This method establishes that this step is necessary because the size of fibers and contaminant particles is minimized at the inlet end, thereby reducing the possibility of clogging of the pores. be. In fact, this is so strong that all Holtz claims include the limitation of a "boat-shaped" shape of the screening slot on the receiving side of the screening cylinder.

Another patent issued to the applicant, Lehman U.S. Pat. This indicates that you have found something wrong with your thinking. More specifically, this patent shows that not only does this screen work without clogging when the screening holes are not highlighted on the receiving side of the cylinder, but also, very surprisingly, when the holes are not highlighted on the receiving side of a conventional cylinder. It has been shown that considerably improved results are obtained when the inlet side of the cylinder is highlighted to the same extent as is normally done.

A recent improvement to the Lehmann patent screen is Lambenius U.S. Pat. No. 4,529,
No. 520, in which the inlet side of the screening cylinder is provided with an axially extending groove of trapezoidal cross section, and a cylindrical screening hole is bored in the bottom of this groove. Lambenius claims that the downstream side of the multichannel is at a relatively oblique angle to the direction of flow of the material passing therethrough, preferably at an angle of about 30°; closely follows the disclosure of Canadian Patent No. 972,322 to Fredrickson, in which screening holes are shown upstream of the groove, or slotted holes are provided downstream thereof. Both of these patents emphasize the desirability of reducing the target area on the inlet side of each screening hole that the fibers "look into" in the flow through.

In the screen of the Lehman patent, the screening holes, both slotted and cylindrical, are arranged with their smallest diameters on the receiving face of the screening cylinder. It is shown. This part of the bore or slot has a relatively small or short axial extent, while the other part of the bore or slot increases in diameter or width towards the inflow side of the cylinder. reaches its maximum size.

According to the invention, the part of the matching hole on the inflow side of the cylinder has an outer diameter that is considerably larger than the part with the smallest diameter, and has a narrower diameter, for example, up to twice the smallest diameter or more. It has been found that screening members employing cylindrical screening holes can provide unexpectedly large effects if the holes are kept relatively small or short in axial size. However, this countersunk section has a relatively small tapered corner, e.g., 22.5 degrees, relative to the surrounding surface of the screening member, so that each of the slotted sections is equally shallow. is preferable.

In a preferred embodiment of the invention, the screening holes are arranged in rows in both the axial and circumferential directions of the screening member.
They are also arranged in a spiral row around the cylinder. The depth and angle of the slotted portions of this hole are arranged in one or more directions such that adjacent portions form a number of relatively sharp ridges along the overlapping portions covering most of the surface of the cylinder. Overlapping or close to each other. The other pores may be uniformly cylindrical, but include a relatively short cylindrical portion of minimum diameter near the inlet portion of the pore, with the other pores relative to the centerline of the portion of minimum diameter. Preferably it tapers outwardly at a small angle.

The screening device shown in FIG. 1 of the present invention is generally similar to that of U.S. Pat.
, No. 543. It comprises a main housing 10 on a base 11, with a raw material inlet chamber 12 having a tangential inlet 13 at the upper end of the housing, which can be pressurized as is customary in such screening equipment. The supply will be made accordingly. A cylindrical screening member 15 passes through the interior of the housing below the inlet chamber 12 into a stock receiving chamber 17 having a central supply chamber 16 and an outlet 18.
Divide into.

The bottom wall 20 of the feed chamber 16 is provided with a control valve system @ 23 that is preconfigurable to provide the desired continuous outflow of wasteful materials.
a trough 21 leading to an outlet 22 provided with a trough 21; The heavy particles remaining in the trough 21 fall from this into a heavy waste collection bin 24 by means of a manually controlled valve 25 for intermittent removal.

The rotor 30 is supported by a drive shaft 31 in the center of the supply chamber 16, also mounted on the base 11, and driven by a motor 33 via a suitable gear mechanism or belt. feather or stick 3
5 is attached to the inner surface of the screening member 15 by means of a support rod 36, and an adjustable connection 37 between the inner end of the rod 36 and the outer surface 30 allows the vane 35 to be attached to the inner surface of the screening member 15 according to standard practice. An appropriate interval is set for each.

The vanes 35 span the entire length of the screening surface of the screening member 15, are helically curved, and are arranged such that the upper end of each vane is spaced forward of the lower end in the direction of rotation of the rotor, indicated as clockwise. It is set up. Although two vanes 35 are shown, other numbers may be used, and generally a larger number, for example four, will allow improved operation with greater certainty.

The screening cylinder 15 is provided with a number of screening holes 40 of circular cross section, which are arranged in rows around the circumference and axial direction of the cylinder to facilitate manufacturing, and which are actually It will cover almost the entire area. The holes are drilled or otherwise formed in a flat metal plate, the metal plate is then rolled into a cylindrical shape, and the joining edges are welded together. A typical plate material thickness that is considered sufficient for the practice of this invention is 0.
．． 478z (0,188 inch) stainless steel.

With particular reference to the enlarged view in FIG. 4, the pores 40 include an inner cylindrical portion 41 of a predetermined minimum diameter, an inflow portion 42;
It consists of three concentric parts, the discharge part 43. The inflow section 42 has a diameter that increases rapidly from a minimum value that coincides with the diameter of the cylindrical section 41 to a maximum value at a surface 44 that is significantly larger than this minimum value.

The portion of smallest diameter 41 may extend all the way to the discharge side 45 as in the case of the Lehman patent, but the discharge portion 43 may be slightly outward to reduce the axial length of the cylindrical portion 41. A tapering in the opposite direction is preferred, and good results have been obtained with a portion 43 tapering outwardly at an angle of 7° to the centerline of the cylindrical portion 41.

For the invention to be successful, each inlet section 42 should have an axial dimension that is significantly smaller than the largest diameter on the inlet side 44 of the screening member, such that it has a relatively thick but relatively prominent outer circumference. is known to be important. This condition is easily established with a conventional slotted hole with a relatively flat taper angle, as shown in Figure 4, and good results were obtained with a taper angle of 22.5° relative to the plane of the flat plate. There is.

As shown, the axial dimensions of the three individual sections 41-43 are such that the combined axial dimension of sections 41 and 42 is less than the dimension of the evacuation section 43. For example, the thickness is 0.478 mm so that the discharge end 43 is twice or more the axial length of the parts 41 and 42 combined.
α (0,188 inch) steel deck from 0.102 to 0
．． Very good results have been obtained with this combined axial length in the range of 152α (0.040 to 0.060 inches).

The diameter and depth of each inlet 42 depend in particular on the size of the corresponding cylindrical section 41 and the spacing of adjacent holes 40 . For preferred results in the practice of the present invention, the relative spacing of adjacent holes and the maximum size of the inflow portion 42 are such that the combined area of the surfaces of the slots is a large portion of the total surface 44 of the screening member. Should. The result of this condition will be that adjacent inlets will closely fit or overlap each other in at least one direction so as to form a plurality of relatively sharp ridges 46 that are arcuate in profile over the entire surface 44.

For example, in one embodiment of the present invention, the minimum diameter of the pores 40 is 0.127aR (0.050 inches), with adjacent holes extending 0.3 mm in the circumferential direction of the screening member on the centerline.
18cIR (0,125 inches), 0.691 axially
There was a spacing of cfR (0,272 inches). Then the maximum radius ('r) at each inlet with a maximum depth of 0.0510 (0,020 inches) is 0.186a (0,07
33 inches), but this is 0 in the circumferential direction of the cylinder.
．． 056cIR (0,022 inches), 0.056cIR (0.022 inches) in the helical direction.
It gave a maximum overlap of 0.025c (0.010 inches). This combined size means that the total area of the pores (πr2 x total number of pores n) exceeds 80% of the surface 44, and the area of other planes is discontinuous and consists of individual small sizes. .

In another example, the holes 4G have a minimum diameter of 0.1571 (0,062 inches) and the circumferential and axial spacing of the screen members are each 0.635 cm.
ffi (0°250 inch) and 0.556CI+ (
0,219 inches). Each inlet is 0.0 on the inner circumference
and an outside diameter of each inlet of 0.568 cIM (0,224 inches) at a depth of 761 (0,030 inches);
This is 0.259 cm in the helical direction of the screening member.
(0.102 inches) and a maximum overlap of 0.013α (o, oos in.) in the circumferential direction of the screening member. The combined area of all the pores (πr271) would theoretically exceed the area of surface 45, excluding overlap.

In another example, the hole 40 is 0.318αm (0,12
5 inches), and the circumferential and axial spacing of their screen members is 0.6353 (0.6353 inches), respectively.
0.250 inch) and 0.953 value (0.375 inch). Each inlet has an inner circumference of 0.076 (:I
(0.030 inches), the outer circumference of each inlet is 0.68601 (0.2 inches), which is 0.68601 (0.2 inches) in the axial direction of the screening member between adjacent inlets.
0.051 υ (0.020 in.) with an overlap of 0.1141 (0.045 in.) in the helical direction of the screening member and 0.0250 (0.10 in.) in the axial direction of the screening member between adjacent inlets. The ridge 46 has the minimum width. The total area of the pores (πT271.) would theoretically exceed the area of surface 45, again excluding the overlap.

Analysis of these examples shows that in each case the area of the slot covers most of the inflow side of the screening member and provides a large number of relatively sharp arcuate edges or ridges. It will be. Testing of some such examples has shown that the combination of irregular flushes caused by the hydraulic action of the vanes or foils on the rotor results in close proximity to the inlet for each screening hole. This produces an irregular vortex pattern, which greatly facilitates an effective screening action.

Although the device configurations described herein constitute preferred embodiments of the invention, the invention is not limited to these device configurations per se, and may be modified in various ways without departing from the scope of the invention. You will see what can be done.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of a pressure screening device according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the inlet side of the screening cylinder of FIG. 1, prior to forming the cylinder from a flat metal sheet. FIG. 3 is a partial cross-sectional view taken along line 3--3 in FIG. FIG. 4 is a further enlarged partial view taken along line 4--4 of FIG. 10... Housing 12... Raw material inflow chamber 15... Screening cylinder 16... Supply chamber 17... Passage stock receiving chamber 30... Rotor 35... Vane 40... Screening Hole 42...Inflow part 43
...Discharge department (5 people outside)

Claims (1)

[Claims] 1. A pressure housing, and a cylindrical screen having a uniform predetermined thickness, the interior of the housing being divided into a raw material inflow chamber and a passing stock receiving chamber, with a number of screening holes passing through. and a rotor including vane means mounted for rotation in said housing to prevent clogging of said holes, wherein: (a) each of said holes is circular in cross-section and of a predetermined minimum diameter; (b) a concentric frustoconical inlet end, each of the holes having a maximum diameter in the plane of the screening member that is substantially greater than both the minimum diameter and the axial dimension of the inlet; (c) the axial size of the inflow end is such that the thickness of the screening member and the maximum diameter of the inflow portion are a fraction of the maximum diameter of the screening member; Device. 2. The screening device according to claim 1, wherein the frustoconical inflow portion forms a relatively small angle with respect to the surrounding surface of the screening member. 3. The screening device according to claim 2, wherein the angle is about 22.5°. 4. The relative spacing of the adjacent holes and the maximum diameter of the inflow end of each of the holes are such that the adjacent inflow ends form a ridge on the inflow side surface of the screening member. A screening device according to claim 1. 5. The screening device according to claim 4, wherein the size is such that at least a portion of the adjacent inflow portions overlap. 6. The holes are arranged in rows in the axial, circumferential, and helical directions of the screening member, and the size is such that adjacent holes in the rows extending in at least one of the directions overlap. A screening device according to claim 4. 7. Each of the inlets has a maximum radius (r), such that the total number of holes (n) multiplied by πr^2 is greater than 1/2 of the total surface area of the screening member. A screening device according to claim 1. 8. Each of the inlets has a maximum radius (r), and the total number of holes multiplied by πr^2 is greater than 3/4 of the total surface area of the screening member. The screening device according to item 1. 9. Each of the inlets has a maximum radius (r), and the total number of holes (n) multiplied by πr^2 is greater than the total surface area of the screening member. The screening device according to scope 1. 10. The screening device of claim 1, wherein each of said holes includes a discharge end having a diameter greater than said minimum diameter over its entire axial length. 11. The screening device of claim 1, wherein the smallest diameter portion of each of the holes has an axial dimension that is a fraction of the thickness of the screening member. 12. The screening according to claim 11, wherein the overall axial size of the inflow portion and the predetermined minimum diameter portion is less than 1/2 of the thickness of the screening member. Device.