Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3832115 A
Publication typeGrant
Publication dateAug 27, 1974
Filing dateMay 23, 1972
Priority dateMay 29, 1971
Also published asCA985999A1, DE2126935A1, DE2126935B2, DE2126935C3
Publication numberUS 3832115 A, US 3832115A, US-A-3832115, US3832115 A, US3832115A
InventorsEttel H
Original AssigneeMende & Co W
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for compressing chipboards
US 3832115 A
Abstract
Improved apparatus for the production of chipboard wherein the gap width between two heated pressing members at the commencement of the pressing operation is smaller than the thickness of the chipboard to be manufactured.
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent 1191 Ettel 1451 Aug. 27, 1974 54 APPARATUS FOR COMPRESSTNG 3,278,659 10/1966 Willy 425/224 x I v 3,309,444 3/1967 Schueler 264/122 X CHIPBO S 3,391,233 7/1968 Polovtseff 425/373 x Inventor: Hubert EH91, Telchhute, rm y 3,632,734 1/1972 Haygreen 264/122 Assignee Wilhelm Maude 3,734,669 5/1973 Ettel 425/373 [22] Filed: May 1972 Primary ExaminerJ. Spencer Overholser [21] Appl.'No.: 256,108 Assistant ExaminerJohn E. Roethel A Attorney, Agent, or FirmMo1inare, Allegretti, Newitt 30 Foreign Application Priority Data wtcoff May 29, 1971 Germany 2126935 57 ABSTRACT [52] US. Cl 425/373, 264/109, 425/224 1 [51] Int. Cl B29j 5/08, B30b 5/04 Improved apparatus for the production of chipboard [58] Field of Search 264/ 109, 112, 122; wherein the gap width between two heated pressing 425/224, 335, 373 members at the commencement of the pressing operai tion is smaller than the thickness of the chipboard to [56] References Cited be manufactured. 2 UNITED STATES PATENTS v 3,216,059 11/1965 Voelskow 425/336 x 3 m 1 Drawing f BACKGROUND OF THE INVENTION The invention relates to an apparatus for producing chipboard, in which a layer or bed of wood chips, to which binders are added, is scattered onto a steel band and the chips moved into a gap between two heated pressing components which compress the wood chip layer to produce the chipboard.

In the prior known apparatus for compressing chipboards, wood chips with added binders are scattered on a steel band, which is moved into a gap between two heated pressure plates. The pressure plates are then moved towards one another and compress the wood chips until a mutual spacing is produced. This spacing is determined by spacer elements between the pressure plates. Since the layer of wood chips settles during the pressing operation, its' resistance to the pressing dies is reduced, and as a result, the compressing pressure can be reduced as the pressing time increases. With these known apparatus for compressing wood chipboards, at no instant is there affected a compression of the layer of wood chips to a dimension which is smaller than the thickness of the chipboard which is to be manufactured. Since the spacer element always guarantee a constant spacing, the layer or bed of the'wood chips is held during the pressing operation at a constant thickness, until the curing of the binder has occurred. In this way, there is no springing back, or at most, only a very slight springing back, depending on'the elastic properties of the manufactured and cured chipboard.

In order to produce smooth surfaces which, as far as possible, are free from pores, it is known to first spread or scatter a layer of fine wood chips, which are to form the lower external surface. A usually thicker layer, which is to form the middle layer of the chipboard to be manufactured is then added to be followed by a top layer of fine chips which forms a smooth upper surface layer. The use of very fine chips did, however, present difficulties in connection with the mixing of the fine chips with binders, which requires a device'for scattering that is substantially more complicated. Furthermore, fine wood chips do not contribute to or increase in strength in the board, particularly with respect to bending strength.

SUMMARY OF THE INVENTION An'object of this invention is to provide a simple arrangement for compressing chipboards, whereby it is possible to produce a smoother surface than with the previously known chipboards and, as far as possible, to

- have a greater strength.

This object which forms the basis of this invention, is achieved by maintaining the width of the gap between the two pressing components at the commencement of the pressing operation at a distance smaller than the thickness of the chipboard to be manufactured.

It was found that by an initial, brief, increased compression of the chip layer to a. dimension smaller than the intended final thickness of the chipboard to be manufactured, an extremely strong compression of the chips is produced. This leads to a very rapid penetration of the heat from the pressing dies or pressing cylinders into the outer zones of the compressed layer or bed of chips, particularly when using a continuously operating arrangement. As a consequence, the outside layer is cured particularly quickly and is given the strength required of it. Moreover, by the high degree of compression, a substantially greater freedom from pores is produced. This leads to a better surface quality.

Since the increased compression to a smaller or undersized dimension takes place for only a short period of time with the apparatus of this invention, the inner portion of the chipboard will spring outwardly again, since curing in this portion has still not occurred. The extent the inner portion springs out is determined by the continuing downstream compressive pressure or the width of the following pressure gap, when using a 'continuously operating arrangement, and by the thickness of the heaped layer of chips and the material properties of the chips. The outward springing produces a smaller chip density in the central region of the board, where, as is known, the chips only contribute to a small degree to the strength of the chipboard. By means of the simple construction of this invention, especially a continuously operating arrangement for the manufacture of chipboards, it is possible to produce a board having high surface quality, high strength, and a low consumption of material which results in a lower 1 weight.

With an apparatus for continuously manufacturing chipboards, the teaching of this invention can be achieved in a quite simple manner by adjusting the gap between two pressure cylinders to a distance smaller than the thickness of the chipboard which is to be manufactured. Following the pressing gap, the'pressure cylinder is wrapped or embraced by a steel band under tension, at a spaced apart distance corresponding to the thickness of the chipboard to be manufactured.

The pressure'cylinders can be mounted for movement relative to one another and can be pressed against one another in such a way that the required narrowing or undersize of the pressure gap is produced at the start of the pressing operation. By pretensioning the pressure cylinders relative to one another at a certain force, heat expansions of the heated pressure cylinders scarcely have any effect.

The pressing cylinders can also be fixedly mounted,

however, it is expedient for at least one pressing cylin-- DETAILED DESCRIPTION OF THE INVENTION AND DRAWING The invention is hereinafter to be more fully ex plained by reference to a constructional example shown in the drawing. Chips 2, to which a binder is added, are scattered by means of a scattering or broadcasting machine 1, on a band 3, which runs continuously in the direction of arrow 4 over a table 5. In this way, a constant layer or bed 6 of chips is formed.

This bed of chips travels on the band 3, which is preferably made of steel, into a gap 7 formed between a large heated pressure cylinder 8 and a small heated pressure cylinder 9. The band 3 wraps around the major part of the pressure cylinder 8 following the gap 7 and then runs around a guide roller 10. In the wrapping region of the pressure cylinder 8, a gap 11 is formed between the cylinder and the band 3. This gap is filled by the compressed wood chips or, strictly speaking, the already partially cured chipboard.

The width of the gap 7 between the pressure cylinders 8 and 9 is smaller than the thickness of the chipboard which is to be manufactured. For example, the width of gap 7 is 3.8 mm when the thickness of the chipboard to be manufactured is 4.2 mm. In turn, the width of the gap 11 is approximately the same as the thickness of the chipboard to be manufactured, i.e., about 4.2 mm.

By the excessive compression in the narrowed gap 7, a particularly intimate thermal contact is produced between the surface of band 3 which rests on the heated pressure cylinder 9, the adjacent region of the layer 6, the surface of the heated pressure cylinder 8 and the opposite surface region of layer 6. This produces a rapid curing of the binder in the chips. Preferably the curing in the region of the gap 7 occurs in at least the surface regions. This curing takes place with a high degree of compression in the gap 7, so that a high density is guaranteed in the surface region of the chipboard to be manufactured.

After leaving the gap 7, the'partially cured chipboard springs out again in the middle region of the board. This is because no curing or only a slight curing has occurred, and as a result, the middle region of the chipboard is no longer as strongly compressed. As a result, in regards to strength, the chipboard has a lower density in the less significant central region. Hence, wood is saved and a lower weight is produced. The curing of the central region of the chipboard then occurs in the gap 11 between the band 3 and the pressing cylinder 8. To "produce a uniform temperature transversely of the chipboard in the region of the gap 11, it may be expedient to additionally heat the band 3 in the wrapping region of the pressing cylinder 8.

In the example as shown, the pressing cylinder 9 is provided with bearings 12,- which are displaceably mounted on a guide 13 substantially in the direction towards the pressing cylinder 8. In this way, the gap 7 between the pressure cylinders 8 and 9 is readily adjustable. The adjustment of gap 7 can be made by appropriate establishment of a certain pressure on the bearing 12 in the direction of the pressure cylinder 8. The width of the gap 7 also depends on the thickness of the layer 6. Layer 6, however, can very easily be kept constant, so that a constant width in the gap 7 is produced.

It is also possible to move the bearings 12 by a con trol mechanism, is not shown. This movement depends on the width of the gap 11 and thus on the thickness of the chipboard to be manufactured.

I claim as my invention:

1. In an apparatus for producing chipboard from a layer of wood chips and binders, said chipboard having a predetermined thickness, said apparatus including a first and second heated pressure member and a steel band, said steel band carrying said layer between said first and second heated pressure members, the improvement comprising means for producing high chip density outer regions and a low chip density intermediate region in said chipboard, said producing means including means for positioning said first heated pressure member relative to said second heated pressure member to initially compress said layer to a thickness less than said predetermined thickness.

2. An improvement as claimed in claim 1 wherein said first heated pressure member is a first pressure cylinder and'said second heated pressure member is a second pressure cylinder, said first and second pressure cylinders defining a gap therebetween, said gap being less than said predetermined thickness.

3'. An improvement as claimed in claim 2 wherein said steel band wraps around a portion of said first pressure cylinder to define a second gap between said steel band and said portion of said second pressure cylinder and downstream from said gap between said first and second pressure cylinders, said second gap being substantially equal to said predetermined thickness.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3216059 *Sep 27, 1962Nov 9, 1965Voelskow PeterApparatus for producing fiberboard sheets
US3278659 *Feb 26, 1963Oct 11, 1966Specialty ConvertersMethod and apparatus for casting foam plastic sheets on a curved casting surface
US3309444 *May 31, 1963Mar 14, 1967Schueler George Berthol EdwardMethod of producing particle board
US3391233 *Jan 16, 1967Jul 2, 1968Boris PolovtseffManufacture of particle board
US3632734 *Jul 28, 1969Jan 4, 1972Univ MinnesotaReduction of springback in particle-board by resin treatment of green particles
US3734669 *Oct 26, 1971May 22, 1973Mende & Co WApparatus for continuous manufacture of chipboard
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3938927 *Apr 22, 1975Feb 17, 1976Hermann Berstorff Maschinenbau GmbhApparatus for the continuous manufacture of chipboard panels, fibre panels or the like
US4011034 *Apr 9, 1976Mar 8, 1977Karl Kroyer St. Anne's LimitedProduction of fibrous sheet material
US4784816 *Sep 16, 1987Nov 15, 1988Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V.Method for continuous manufacture of inorganically bonded materials, especially material slabs
US4882114 *Mar 16, 1989Nov 21, 1989The Wiggins Teape Group LimitedMolding of fiber reinforced plastic articles
US4957805 *Jul 11, 1988Sep 18, 1990The Wiggins Teape Group LimitedConsolidation using heat and pressure
US4964935 *Aug 3, 1989Oct 23, 1990The Wiggins Teape Group LimitedMethod of making fibre reinforced thermoplastics material structure
US4978489 *May 31, 1989Dec 18, 1990The Wiggins Teape Group LimitedProcess for the manufacture of a permeable sheet-like fibrous structure
US4981636 *Mar 11, 1988Jan 1, 1991The Wiggins Teape Group LimitedFibre reinforced plastics structures
US5053449 *Nov 29, 1988Oct 1, 1991The Wiggins Teape Group LimitedPlastics material
US5215627 *Jul 14, 1992Jun 1, 1993The Wiggins Teape Group LimitedMethod of making a water laid fibrous web containing one or more fine powders
US5242749 *Aug 7, 1990Sep 7, 1993The Wiggins Teape Group LimitedFibers and unconsolidated particles of non-crosslinked elastomer bonded togather
US5558931 *Jul 9, 1990Sep 24, 1996The Wiggins Teape Group LimitedFibre reinforced thermoplastics material structure
US5639324 *Jul 2, 1990Jun 17, 1997The Wiggins Teape Group LimitedMethod of making laminated reinforced thermoplastic sheets and articles made therefrom
Classifications
U.S. Classification425/373, 264/109, 425/224
International ClassificationB27N3/08, B30B3/00, B27N3/26, B27N3/24
Cooperative ClassificationB27N3/26
European ClassificationB27N3/26