Patent Grant
8469199
The present invention relates to a screen element adapted to be arranged in a screen frame, which has longitudinal sides adapted to be arranged in a longitudinal direction of the screen frame and transverse sides adapted to be arranged in a transverse direction of the screen frame. The invention also relates to a screen, which has a screen frame and screen elements arranged in the screen frame, the screen elements having longitudinal sides arranged in a longitudinal direction of the screen frame and transverse sides arranged in a transverse direction of the screen frame.
Screen elements and screens of the above type are known, for instance, from EP-A-26 961 and US-RE 38,303 E which disclose different types of screens with screen elements arranged in a screen frame.
These screens have several advantages compared with those of earlier generations since individual screen elements can be exchanged when worn out, and since this exchange is a relative simple procedure which can be performed without requiring much work and equipment.
Since screen decks of the type above are subjected to longitudinal forces and also have screen elements arranged on a frame comprising longitudinally oriented bars, the screen elements must be locked somehow in the longitudinal direction to prevent sliding. A conventional way of achieving this is screwing into the side walls of the screen frame.
The screen elements should have an active surface that is as large as possible. The active surface is normally limited by the rigidity of the screen element since a screen element of lower strength requires supporting sections arranged at shorter intervals, which results in an increased dead surface of the screen element. Nevertheless, letting the entire screening surface consist of a single screen element and reducing the number of supporting points to a minimum does not constitute a convenient alternative. Such a method would certainly provide a maximum surface, but at the price of very high operating expenses since it would be necessary to exchange the entire screen deck also in case of local wear.
Consequently it is desirable to have a screen deck with a large active surface and high stability, on which it would be easy to exchange individual elements.
WO 89/08509 discloses what is referred to as a step deck, i.e. a screen where the successively arranged screen elements overlap each other to form a stepped screening surface.
The present invention intends to satisfy the above criteria and solve the above-mentioned problems by providing a new screen element and a new screen of the type stated by way of introduction.
These objects are achieved by means of a screen element according to claim 1. Preferred embodiments are defined in claims 2-12.
The above-mentioned objects are also achieved by a screen according to claim 13, preferred embodiments being defined in claims 14-20.
The transverse sides of the inventive screen element are provided with at least one projection and/or at least one recess. As a result, neighbouring screen elements can engage each other lockingly in a direction transversely to the plane of the screen element. Neighbouring elements are thus held together in the vertical direction and the risk of forming gaps between the short sides of neighbouring screen elements is reduced, which in turn reduces the need for a support frame in the transverse direction.
It is preferred for the screen element to have on its underside an undercut groove, which simplifies the snap locking to the screen frame.
Preferably, the undercut groove extends in the longitudinal direction of the screen frame to be attached to a longitudinal attachment section of the screen frame.
An inventive screen element is further made of elastomeric material and preferably of elastomeric material with two different hardnesses. This provides stability and rigidity while at the same time great abrasion resistance is ensured.
According to a characteristic feature, the upper side of the screen element has a lower hardness than the underside of the screen element so as to provide a stable and rigid structure with an abrasion-resistant surface.
The elastomeric material adjacent to the undercut groove preferably has two different hardnesses, so that the material on one groove side adapted to face another screen element has a lower hardness than on the opposite side of the groove. With snap locking to the screen frame, this results in bulging of the softer side of the groove facing another element, which in turn establishes an improved seal between neighbouring elements.
The elastomeric material mentioned above preferably is polyurethane (PU), since screen elements of this material are suitable for the technical purpose and also cost-effective to manufacture.
The polyurethane screen element has, if required, a reinforcement of polycarbonate resin (PC). Polycarbonate resin has been found to bond excellently to polyurethane in manufacture and ensures excellent reinforcing properties. Moreover a PC-reinforced PU material has the advantage, compared with a PU material reinforced with, for instance, steel, that it is easy and inexpensive to degrade once it is worn out.
An inventive screen element preferably has at least one projection and/or at least one recess which are arranged in the long side thereof. They allow locking engagement with a corresponding projection and recess in the long sides of neighbouring screen elements. The engagement ensures that the screen elements do not slide relative to each other.
The projection/projections and recess/recesses of the screen element is/are preferably arranged in such a manner that the screen element when rotated half a turn about an axis in the normal direction of the screening surface has the same circumferential shape. This symmetry makes it possible to turn over an individual screen element, for instance in case of uneven wear on the surface of the screen element.
According to a characteristic feature, the underside of the screen element is cambered at the short sides. Camber increases the rigidity of the screen element in the transverse direction and, together with the locking engagement of the short sides, results in the screen frame not requiring any supporting devices in the trans-verse direction, even when subjected to high loads.
A screen according to the present invention has a screen frame and comprises screen elements which are arranged in the screen frame with longitudinal sides in the longitudinal direction of the screen frame and trans-verse sides in the transverse direction of the screen frame. Moreover the short sides of the screen elements are provided with at least one projection and/or at least one recess for locking engagement with a corresponding projection and/or recess on neighbouring screen elements arranged in the screen frame. The engagement locks the screen elements to each other in the thickness direction of the screen elements.
In one embodiment, the screen elements of the screen engage the screen frame by means of an undercut groove formed in the underside of the screen elements. The undercut groove allows simple and easily mounted snap locking and also each individual element to be safely held.
The screen frame preferably comprises a longitudinally extending attachment section, to which the screen elements are fastened by snap locking by means of their undercut groove. The attachment section makes it possible to individually adjust the shape of the screen deck without structurally modifying the underlying frame structure.
In one embodiment, the attachment section is stepped in the longitudinal direction of the screen frame, whereby the screen elements fastened to the attachment section form a stepped screening surface. A stepped screening surface turns the material that is being screened and thus improves screening efficiency.
Moreover the attachment section is preferably symmetrical in the transverse direction to allow turning of the attachment section, which provides a longer life.
The screen elements of the screen are on their long sides preferably provided with at least one projection and/or at least one recess for locking engagement, in the longitudinal direction of the screen frame, with a corresponding projection and/or recess on neighbouring screen elements arranged in the screen frame. This gives the screen additional stability since the screen elements are not only supported by the attachment section but also locked to each other by the engagement between the projections/recesses on their short and long sides.
According to a characteristic feature, said at least one projection and/or recess on the longitudinal sides and the transverse sides, respectively, are arranged so that the screen element when rotated half a turn about an axis in the normal direction of the screen surface has the same circumferential shape. This property increases the flexibility and cost-efficiency of the screen since local wear on an individual screen element can be alleviated by turning of the individual screen element.
Furthermore the at least one projection and the at least one recess on the outer long sides of the transversely outermost screen elements engage a corresponding projection and/or recess in the wall guard of the screen frame, whereby these screen elements and thus the entire screening surface are locked. Due to the snap locking and the locking engagement, the screening surface cannot be moved, either transversely or longitudinally.
The invention will in the following be described by way of example based on two embodiments and with reference to the accompanying drawings, in which
a-f are sectional views of attachment sections for attachment of the screen elements according to the invention.
The screen 1 shown in
The screen element 2 has, as is more clearly to be seen in
The longitudinally oriented long side of the screen element 2 further has projections 8 and recesses 9, which lockingly engage corresponding recesses 9 and projections 8 on neighbouring screen elements 2.
The recesses 7, 9 and the projections 6, 8 are arranged along the circumference of the screen element 2 in such a manner that the screen element can be rotated half a turn about an axis in the normal direction of the screening surface and then again be positioned in the screen 1. If the screen element 2 is worn at one point on its surface, it can thus be rotated half a turn, instead of being exchanged.
In this first embodiment, the screen element 2 has on its underside cambers 13 to increase its rigidity.
The screen frame wall guard 10, which is screwed to the screen frame wall (not shown), has projections 11 and recesses 12 which engage the projections 8 and the recesses 9 on the outer long sides of the transversely outermost screen elements 8, thereby locking these screen elements and thus also the entire screening surface. The snap locking and the locking engagement prevent the screening surface from being moved, either transversely or longitudinally.
Deflectors 14 and blocking strips 15 are mounted in recesses formed on the screen 1 in the screen elements 2.
a-c show examples of cross-sections of the attachment section 4. The attachment sections used in the screen 1 in
According to a second embodiment of the inventive screen as shown in
The projections 106 and the recesses 107 of the screen elements 102 here ensure increased tightness in the joint between successively arranged screen elements 102 compared with prior-art step decks.
The stepped attachment section 104 ensures an alternative way of providing a step deck. In prior-art step decks, the section has been straight and the screening elements have instead been placed overlapping each other.
d-f show examples of cross-sections of the attachment section 104.
A person skilled in the art should realise that a large number of modifications of the here described embodiments of the invention are conceivable within the scope of the invention which is defined in the appended claims.
For example, the hardnesses of the material of which the screen elements are made can be varied depending on how the screen is to be used. Suitable hardnesses of the material in the upper side of the screen elements are in many cases 30-90° Shore A and in the underside 35-75° Shore D. The abrasion resistance of the screening surface can also be improved by means of ceramic elements.
Standard components, such as blocking strips and deflectors, can be mounted in other configurations and can also be completely excluded.
The shape of the attachment section can be appropriately designed; for instance the thickness of material and the distribution of material can be adjusted to the loads exerted, without deviating from the object of the invention.
In the two embodiments described, the elastomeric material of the screen elements can be reinforced with polycarbonate resin, when needed.
In the embodiments illustrated, the screening surface is an integral part of the screen elements, but this screening surface can be replaced by, for example, metal wire mesh or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0402219 | Sep 2004 | SE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/SE2005/001303 | 9/9/2005 | WO | 00 | 5/21/2008 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/031176 | 3/23/2006 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4141821 | Wolff | Feb 1979 | A |
| 4265742 | Bucker et al. | May 1981 | A |
| 4661245 | Rutherford et al. | Apr 1987 | A |
| 4839045 | Wildner | Jun 1989 | A |
| 4885040 | Wolff | Dec 1989 | A |
| 4892767 | Freissle | Jan 1990 | A |
| 5049262 | Galton et al. | Sep 1991 | A |
| 5735409 | Malmberg | Apr 1998 | A |
| RE38303 | Askew | Nov 2003 | E |
| 7063214 | Schulte et al. | Jun 2006 | B2 |
| 7296685 | Malmberg | Nov 2007 | B2 |
| 7717269 | Bacho et al. | May 2010 | B2 |
| Number | Date | Country |
|---|---|---|
| 2754044 | Apr 1979 | DE |
| 2754374 | Jun 1979 | DE |
| 4136898 | May 1993 | DE |
| 0026961 | Mar 1980 | EP |
| 0167999 | Jan 1986 | EP |
| 0669170 | Aug 1995 | EP |
| 2104089 | Oct 1993 | ES |
| 2245191 | Jan 1992 | GB |
| 2001701 | Oct 1993 | RU |
| 2101100 | Oct 1998 | RU |
| 8402290 | Jun 1984 | WO |
| WO 8909509 | Mar 1989 | WO |
| WO 9833604 | Aug 1998 | WO |
| Entry |
|---|
| Examiners Report of the Intellectual Property Office of Canada dated Dec. 19, 2011, in counterpart Application No. 2,579,136. |
| Office Action of the Argentina National Administration of Patents dated Nov. 25, 2011 in counterpart Application No. AR 054708. |
| Number | Date | Country | |
|---|---|---|---|
| 20090050539 A1 | Feb 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60609980 | Sep 2004 | US |
