Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Separating means
Reexamination Certificate
1999-09-13
2001-05-22
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Separating means
C209S668000, C209S517000, C209S659000, C209S660000, C209S670000, C209S671000, C209S672000
Reexamination Certificate
active
06234322
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a device with rollers to separate chips and particles of wood or material similar to wood of different gradings, and also the forming machine employing the said roller device, as set forth in the respective main claims.
The invention is applied in machines employed to select chips and particles according to their grading from a loose mass in the form of chips, shavings, fibres, granules etc., in order to then use the material, separated according to the different gradings, in the same machines.
To be more exact, the invention is applied to a separating device with a bed of rollers employed as a screen for chips, particles or fibres, of wood or material similar to wood, to be used by the said machine or to be sent to other processing, for example to refining processes for those parts not suitable for gravimetric selection, to gluing processes or other desired processes.
The invention is also applied to forming machines suitable to select the material according to its grading size and deposit it in super-imposed layers, each having its own range of different gradings; the layered mat thus formed is then generally sent to a pressing process to produce panels of wood or material similar to wood.
BACKGROUND OF THE INVENTION
For some time the state of the art has included screening devices to separate and select chips and particles according to their gradings from a loose or fibrous mass, whether it be dry or wet, generally but not exclusively of wood-based material.
Although the state of the art covers separating devices incorporating rollers, comprising adjacent rollers which rotate in the same direction and which define a bed on which the material to be selected is fed, in the past, and in the industrial field there was a large-scale preference to use screens of the type with a vibrating or oscillating netting, or also with rotary disks.
Within the range of these devices, screens with netting or with disks have been developed with one or more levels or orders of selecting elements; screens with netting or with disks using respectively meshes or gaps where the passage area is progressively increased, or also screens with netting or a disk with transverse bands, where the opening distance is progressively increased in order to discharge particles with a progressively increasing grading.
It is only in recent times that the use of screens and forming machines incorporating rollers has become of considerable importance in the industrial field, especially since materials which are highly resistant to wear, such as special steels, high resistance linings, etc., have become available at a reasonable cost.
The availability of these materials with very high surface resistance and hardness has made it possible, in recent years, to produce and employ separating devices with rollers, which have a great efficiency of production, a long life, and limited or no maintenance; this has made the applications of these machines, both simple screens on one or more levels, and also forming machines, extremely advantageous.
Although the technology of roller screens has been known to the state of the art for many years, it is only in recent years that it has found a real, large-scale industrial application, for the reasons given above.
In the light of these developments, linked to the increasingly evolved types of material available, there have been trials and experimentations in the field on solutions which substantially reproduce the effects and the functions of screens with netting and with disks, though their efficiency has been increased, thanks to the natural functionality of roller devices.
The natural functionality of roller devices is shown particularly in the selection of the fine particles, since the use of rollers instead of, for example, disks mounted on disk-bearing shafts, makes it possible to accurately gauge the gaps to an extremely reduced size which is both continuous and constant.
When disks are used, in fact, the discharge gap is of a substantially rectangular shape, where the distance between the surfaces of the adjacent disk-bearing shafts determines the length of the particles to be selected, while the distance between two adjacent disks mounted on the same shaft determines the thickness of the particles to be selected.
It should however be noted that neither netting screens nor disk screens normally allow the discharge gap in the individual sections of the selection bed to be varied during the operating cycle.
The natural functionality of roller devices has the following direct, resulting advantages:
the preferential choice of the reliefs on the surfaces of the rollers in order to obtain a more coherent screening with the chips, particles and fibres available, and with the specific desired result;
the possibility to distance the rollers reciprocally, both on the horizontal and vertical plane, so as to vary the discharge gap even during the operating cycle, and also to adjust, if so required, the speed of rotation of the rollers, also during the operating cycle.
These features have been the object of a multitude of patents, filed at different times and at long intervals, and therefore their solutions must be considered according to what technology was available at that specific time, with particular reference to the materials available and usable in the industrial field.
For example, U.S. Pat. No. 1,424, published in 1839, already discloses a separating device, in this case for the screening of lead oxide, including adjacent rollers equipped with grooves and penetrating peaks.
U.S. Pat. No. 292,656 also discloses rollers, with mating V-shaped threads on the surface, with a sloping and substantially helical development.
However, this embodiment has the disadvantage that it progressively displaces the material to be selected in a transverse direction with respect to the direction of feed.
U.S. Pat. No. 1,173,737, published in 1916, includes a screener with parallel rollers where the rollers include grooves cooperating with the mating tapered peaks of the adjacent rollers, and where the grooves are not penetrated by the peaks but together define a constant gap through which the particles can pass, the gap being substantially perpendicular to the direction of feed of the material.
U.S. Pat. No. 4,452,694 describes a selection device consisting of a plurality of disks arranged in a line in a plurality of parallel axes forming all together a conveyor bed for the material to be selected, the material being transported in a direction substantially at a right angle to the axis of the disks.
This conveyor bed includes a feeder end on one side and a discharge end at the other.
According to this document, the peripheral surface of the disks includes disks with protrusions or tapered peaks which position themselves in a mating position with tapered recesses or grooves on the adjacent disks.
According to this document, moreover, the rotary speeds of the disk-bearing shafts can be different.
WO 86/01580 refers to selection devices used in incinerator plants. It uses rollers which have on their surfaces protruding ribs with a development substantially parallel to the axis of the relative roller; the walls of the ribs are substantially perpendicular to the roller.
The ribs of one roller face the ribs of the other roller, but do not mutually penetrate each other, so that the discharge gap is substantially linear.
U.S. Pat. No. 3,387,795 discloses a device to process fibrous material comprising a plurality of adjacent rollers which include on their circumferential surface pyramid-shaped tapered protrusions, separated by tapered grooves, the protrusions penetrating at least partly into the tapered grooves of the adjacent roller.
EP-B-328.067 discloses a roller device where the outer circumferential surface of the rollers has individual tapered pyramid-shaped protuberances, developing substantially in a spiral around the surface of the rollers and extending lengthwise, separated by tapered grooves.
The tips of the protuberances of two adjacent rollers fac
Antonelli Terry Stout & Kraus LLP
Beauchaine Mark J
PAL Srl
Walsh Donald P.
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