CA1132327A - Apparatus for the pressing of mats of pressable material, especially for the production of particle board and a method of operating same - Google Patents
Apparatus for the pressing of mats of pressable material, especially for the production of particle board and a method of operating sameInfo
- Publication number
- CA1132327A CA1132327A CA345,926A CA345926A CA1132327A CA 1132327 A CA1132327 A CA 1132327A CA 345926 A CA345926 A CA 345926A CA 1132327 A CA1132327 A CA 1132327A
- Authority
- CA
- Canada
- Prior art keywords
- movable
- press
- bed
- mat
- platen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B1/00—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen
- B30B1/32—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen by plungers under fluid pressure
- B30B1/34—Presses, using a press ram, characterised by the features of the drive therefor, pressure being transmitted directly, or through simple thrust or tension members only, to the press ram or platen by plungers under fluid pressure involving a plurality of plungers acting on the platen
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/007—Means for maintaining the press table, the press platen or the press ram against tilting or deflection
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Control Of Presses (AREA)
- Dry Formation Of Fiberboard And The Like (AREA)
- Press Drives And Press Lines (AREA)
- Presses And Accessory Devices Thereof (AREA)
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A platen press, and a method of operating same, for the planar and parallel pressing of particle board and like materials comprises a press bed and a press plate, one of which is movable and is provided with a hydraulic system for developing the pressing force. A pair of spacer bars are provided on the press bed to flank the particle board and set of bearing cylinders urges the movable press member to clamp the movable member against the spacers, thereby imparting a bend or distortion to the movable press member. This distortion is measured and the measured value is used to operate the main press cylinders to eliminate the distortion and ensure parallel compression of the particle-board mass.
A platen press, and a method of operating same, for the planar and parallel pressing of particle board and like materials comprises a press bed and a press plate, one of which is movable and is provided with a hydraulic system for developing the pressing force. A pair of spacer bars are provided on the press bed to flank the particle board and set of bearing cylinders urges the movable press member to clamp the movable member against the spacers, thereby imparting a bend or distortion to the movable press member. This distortion is measured and the measured value is used to operate the main press cylinders to eliminate the distortion and ensure parallel compression of the particle-board mass.
Description
APPARATUS FOR THE PRESSING OF MATS OF
PRESSABLE MATERIAL, ESPECIALLY FOR THE PRODUCTION
OF PARTICLE BOARD, AND A METHOD OF OPERATING SAME
My present invention relates to an apparatus for the compression of mats of pressable material, especially mats of wood, cellulosic or like materials for the production of pressed board. The invention also relates to a method of operating such a press and, more particularly, to improvements in the parallel compression of pressed board, i.e. the formation of pressed board with a high degree of regularity and planarity or parallelity of its surfaces.
In the production of pressed board it is known to provide platen presses or the like in which a mat of a material capable of fusion to form the pressed board is compressed between two planar surfaces, generally forming the bedplate and headplate of a pla~en press.
Typical of the systems provided for this purpose is that of my U.S. patent 3,860,831 and the earlier systems described or referenced in that patent.
113~2~Z7 ~89 The term "pressed board" is gen~rally referred to in its most generic sense to identify hardboard, i.e. material of high structural strength, low flu~d permeability and excellent surface characteristics, as well as to less dense and highly porous boards which may be used as thermal or acoustical insulation, for interior finishing, or the like. The term is generic to any relatively rigid generally flat board structure, forn~ed by compression utiliz-ing both heat and pressure, to bond fibers, chips or dust of wood or some other material, e.g. a cellulosic material, with intrinsic 10 ~ thermally activatable binder or an added binder, the board being pressed from a structure which, for convenience, will be defined as a mat.
The ter~ "mat" is used herein likewise in its most generic and general sense to refer to a layer of more or less coherently interrelated particles and the binder.
The aforementioned publications describe how such materials may be introduced into a platen press and how thP finished board may be carried away for further processing.
It is known to provide a platen press for the compaction of particle board mats, i.e. for the production of chi?board, fiberboard and sawdust board, which comprises a press frame or support structure, a fixed press plate or bed, a movable press plate or bed, and a multiplicity of working cylinder arrangements which are disposed symmetrically with respect to a vertical median longitudinal plane through the press. The working cylinder arrange-ments will each be understood to include at least one cyllnder and at least one piston, either the cylind~r or the piston being con-nected to the press support or frame while the other of these member~
is connected to the movable press plate.
113~2~7 ~89 Such systems have also been provided here~ofore wlth a plurality of auxiliary piston-and-cylinder arrangements which can be used to modify the orientation of the movable press ~ember so as to ensure generally parall,el pressing of the board.
Naturally, control systems can be provided for the hydraulic piston-and-cylinder arrangements.
The movable and stationary press beds are generally formed with pressing plates which can be heated, e.g. electrically or by fluid heating techniques, the movable and/or stationary beds each including, in addition to the resp~ctive press plate, a plurality of beams which generally extend transversely of the longitudinal a~is oE the press and serve as points of attack for the hydraulic cylinder arrangements.
Naturally, for high quality pressed board, it is desirable that the compression be of the parallel type. The term "parallel compression" is used herein to indicate that the upper and lower faces of the pressed board, at least as the latter emerges from the press, are as close to parallel to one another as possible.
Since these surfaces are also usually planar, reference may also be made to plane-paràllel surfaces.
Plane-parallel surfaces of a pressed board indicate that neither surface has bulges which can be considered as deviations from planarity, furthermore the parallel requirement specifies that the board is of uniform thickness throughout its length and breadth.
Obvlously, for plane parallel compression of the pressed--material mat~ it is essential to compensate for any elastic deformation of the pressing beams, the beds or the pressing plates.
1~8 3, ~ z,7 A pressing frame, as here described is intended to include any type of press support commonly in use. For example, the press support may be a post structure carrying the bed and upon which the upper member of the press is mounted, e.g. a headplate, or a row of portal frames spaced apart in the longitudinal dimension of the press. A system of the latter type is shown for the platen press of U S. patent 3,8~0,381.
The movable press member or bed can be either the upper or the lower bed.
The movable press bed is ge~erally lighter than the fixed press bed and, when the deformation of the press beds is con-s~dered, is the more readily deformed member.
~ f parallel compression of the mat and the boards is desired without compensation by the prior-art techniques, ~ne must either resort to extraordinarily massive press beds, încapable of any deformation during the pressing operation, or must accept a certain degree of convex or concave curvature resulting from the distortion of the movable press bed.
It is possible, following the pressing operation, to remove the convex or concave curvat~re in the pressed board by expensive an~ time-consuming shaping, material-removal or like aftertreatments.
The principles here described are applicable to the single-stage or single-level platen presses of the type describPd in the afore-mentioned patent as well as to double-level or two-stage presses as likewise have been illustrated therein. In the latter case, ~89 the fixed press bed is the intermediate bed, the upper and lower plates being movable. me principles are also apDlicable to multilevel presses in which the press plates between the stages are movable. In this case, of course, the parallel compression must be dealt with as a sum so that the individual distortions of the intervening plates as well as the upper or lower movable plate can be compensated. Finally, the system described will be understood to be applicable as well to the compression of asbestos cement plates or boards and the like.
The prior-art apparatus, represented for example in German patent document (open application - Offenlegungsschrift~
DE-OS 15 02 042, is shown as a single-level press. In this apparatus, the working piston-and-cylinder arrangements are disposed outwardly, as seen in plan view, of the longitudinal median plane of the press and their respective points of attack lie inwardly of the spacer bars which are provided between the press plates to establish the thickness of the pressed board to be formed in the press.
The auxiliary piston-and-cylinder arrangements, provided primarily to equalize or compensate for distortion of the movable press plate, are disposed generally in the region of the longi-tudinal vertical median plane of the press. These auxiliary cylinders thus act as compensating cylinder arrangements which are intended to level the aforementioned deformations of the movable press member under the control o a control arrangement or device.
3Z'~
~89 The movable press member, in the operation of the con-ventional apparatus, is inltially displaced by actuating all or individual ones of the compensating cylinder arrange~ents downward-ly until the press plate comes to lie on the mat to be compressed.
During this step, the working cylinders are merely entrained.
The respective pressurizable compartments behind the pistons o these cylinders are, of course, filled with fluid, e.g. from an accumu-lator or sto~age vessel, although an ele~ted pressure is not generated in these compartments during the entrainment phase.
When the press plate contacts the mat, the working cylinders are actuated so that their pistons apply the full pressure to the plate and are driven by the full hydraulic pressure in the compression mode. ~his, of course, forces the upper or movable press plate downwardly to compact the ma-.
As already implied, the working cylinders are disposcd relatively far from the spacer bars. As a consequence, upon com-pression of the mat, depending upon the nature of the material pressed and the height of the layer forming the mat, the movable press plate deforms or bulges to a greater or lesser extent together with the pressing beam.
When the pressing plate of the movable bed engages the spacer bars, the pressure in the working cylinders increases markedly, Pressure-sensing devices respond to this pressure increase and generate a control pulse which cuts o~f the main cylinders and, in some cases, relieves them. By contrast, the compensating cylinders generally remain under the working pressure to compensate for the bulging or deformation of the movable press bed.
1132~7 If the bulge is in the direction of the fixed bed, the corresponding compensating cylinder is relieved. Conversely, if the bulge is in the direction opposite the fixed bed, the compen-sating rylinder may be additionally pressurized. Naturally, the compensating operati~ns must be determined experimentally for each type o mat, for each board-producing program, for the varlous pressure levels and pressing periods operatin~ in the press.
Even with these empirical derivations of the response to be made by the compensating cylinders, one cannot complet~ly exclude significant variations resulting from changes in the nature of the mat or the like. The same applies for the si~nificant variations in the counterpressure generated in the mat and opposing ad~ance of the movable press plate during the pressing operation and resulting from premature hardening of ~he binder or variations in the moisture level in the particle material of the mat under the effect of heat from the heatin~ plates.
As a consequence, the response of the movable press plate to the particular pressing operation cannot always be determined in advance an~ even when determined in advance, is not necessarily constant or reproducible.
As a consequence, the control method of the prior art is extremely complicated and must permit relatively large tolerances.
It is, therefore, practically impossible with the prior-art system to provide plane parallelity of the pressed boards with extremely narrow or small tolerances.
~323~7 ~8 9 Another disadvantage of ~he prior-art system is that signlficant moments are generated betr~een the main cylinders and the spacer bars in the press plates so that the press plates can impart to the boards a substantially corrugated surface which must be sanded down or otherwise treated. This is especially the case when the movable press bed is ma~e relatively light to save material and hence is especially bendable.
Reference may be had to German patent document (printed application - Auslegeschrif~ DE-AS 17 03 297 in which si~ilar problems may arise although spacer bars are avoided and the working cylinders or main cylinders are provided at the outer edges of the movable press bed or plate.
Another system, represented by German patent document (utility model - Gebrauchsmuster) DE - GBM lg 24 142 in which the main cylinder arrangements are disposed along the edge of the movable press bed and the press plates are so arranged that these main cylinders lie directly above the spacer bars. This, however, precludes a proper compensating operation to cvercome deformation of the movable press bed or plate.
It is the principal object of the present disclosure to provide a press, particularly a platen press, for the pressing of particle-board mats whereby the finished product can be of high planar parallelity and with limited tolerances, while avoiding disadvantages of earlier systems as enumerated above.
1~L3;2327 68 ~
It is another object o~ ~is disclosure to provide an improved method of operating a platen~press so as to eliminate the drawbacks of the earlier systems described.
Still another object of the presént disclosure is to provide a press for the purposes described in which a movable press bed can be given a statically determined position for each pressing operation so that compensation of the deformation of ~he press plate can be effected simply and read;ly.
Yet another object of the disclosure is to provide an improved method of pressing mats to produce pressed board of high plane parallelity.
These objects and others which will become apparent here-inafter are attained, in a platen press for the compaction of particle-board mats which comprises a fixed plate, a movable plate, main fluid-operated cylinders ef-fective to generate the pressure required to convert the mat into pressed board and acting upon the movable plate.
The mat is flanked by spacer bars which rest upon the fixed plate and the auxiliary cylinders are formed as bearing cylinders,positioned over the spacer bars, so as to press the movable plate against these bars and thereby retain the movable plate against these bars during the subsequent operation of the main cylinders.
Means is pro-vided to respond to deformation of the movable plate, such means _9_ 113~3Z7 6~
forming part of the control system for the main cylinders so that the latter are actuated in re~ponse to deformation to the movable plate to level such deformation and ensure parallel compression of the mat.
During this latter operative step, the movable plate acts as a beam supported at two spaced-apart l~tions of pedestals, corresponding to the spacer bars against which the beam or platen is held.
The term "plate" has been used above to refer to the movable p~aten and thus is utilized in its most general sense to mean the movable press member which compacts the mat and which can be heated as described previously. Naturally this movable platen can include any beams or bed structure to which the cylinders are connected and an~ plate or the li~e attached to such bed structures or actual engagement with the mat and the spacer bar. The bed structure may be formed by anothex plate or by an array of girders, crossbeams, spars or the li~e. Since the spacer bars are dis-posed outwardly of the ~ats to flank the latter, the auxiliary or bearing cylinders likewise are disposed outwardly of the main cylinders.
The term "cy-linders" as used above and subsequently herein is intended to refer to fluid-operated ram or jack structureS
which may also be described as piston-and-cylinder arrangements.
In such arrangements, a piston is telescopically slidable in a cylinder chamber or cylinder proper, being displaced by pres-surization of a compartment behind the piston, generally with a liquid medium. While the cylinder prefereably bears upon a fixed support structure, e.g. a portal frame as described above and the piston then acts upon the movable press bed, a reverse ~23~
kinematic constructi~n is also possible whereby the piston is affixed to the stationary support whi~e the cylinder acts upon the movable bed.
Thus the system disclosed dlstinguishes from the state of the art mentioned presiously by utilizing the auxiliary piston-and-cylinder arrangements as bearing cylinder units which apply force directly to the mcvable bed in line with the spacer bars to clamp the spacer bar between the bearing 10 cylinder and the fixed bed of the press, while the control means for the main cylinders includes the deformation-measuring device which reeponds to deforma~ion of the movable press bed and con-trols the main cylinders in response to the measured deformation to displace the movable bed so as to level the deformat~on and 15 ensure parallel compression.
From elementary statistics, the statically determined problem in analy~ing the response of beams on two supports is well know. Correspondingly, a plate of platen which rests upon two spaced-apart supports and is held thereagainst at its edges, 20 presents a statically determined problem.
Thus, the vress plate of the movable press bed is initially brought to bear upon the mat to be compressed, either with the bearing cylinder ar-rangements or with the main cylinder arrangements or both~
Generally it is more convenient to advance the movable bed with the bearing cylinders and to simply entrain the working or main cylinders with the movement of this bed.
Z~327 .
Next, the bearing cylinders forcibly apply the ~ovable bed to the spacers to form the statically determined structure of a plate mounted upon the supports in the manner described. In general this wlll result in a convex deformati~n of the movable S press bed and its plate,which deformation can be readily measur-ed and determined.
When reference is made to deformation measurement of the movable bed it should be understood that the deformation measure-ment can be made upon the press beams or upon the plate proper since deformation of the one is followed or produces deformation of the other.
The operation of the main cylinders is so controlled that this deformation is compensated and hence a parallel compression is applied to the mat which is automatically maintained during any further compression-In order to exclude the tapering of the pressed board duringthe pressing to one edge, a preferred embodiment of the invention provides that the auxiliary or bearing cylinders are pivotally connected to the support and to the movable bed. This, of course, means that the piston is hinged to either the frame or the movable bed while the cylinder proper is hinged to the other.
According to another feature, the spacer bars can have a width such that the bearing force, i.e. the force ap-plied by the bearing cylinders, is spread by the bars and perma-nent (plastic or inelastic) deformation of the beds and the re-spective plates of the press are avoided.
1~32;3~7 116~
Indeed, German patent document (printed application- Aus-legeschrift) DE-AS 16 53 187 describes relatively wide spacer bars, although not in an equivalent relationship to bearing cylinders or the liXe.
~he movable press bed herein described is advan-tageously comparatively light and preferably is so designed as to be elastically deformable but not compressible under the standard pressing forces which are used. Naturally, this means that both the beams of the movable bed and the press plate there-of should be elastically deformable. This guarantees light--weight construction of the movable platen and makes the system more responsive to the control operation described above.
While the deformation measurement can be effected by any conventional means it is preferred to provide the deformation--measuring device as a strain gauge whose strips are mounted upon the beams or the plates of the movable bed.
-The output of the strain gauge can be used by applying it to a conventional control circuit to operate the hydraulic system by techniques well known in the control arts.
The system here described has the advantage that it utilizes a statically determined position for the press plate at the beginning of the deformation-compensation operation and hence also ma~es use of statically determined responses of the disadvantages described previously. A relatively simple control system can be provided for this purpose~
.
i~3;~2~
More particularly in accordance with a first aspect of the invention there is provided a platen press for the compression of a mat to produce a board, comprising:
a support;
a rigid fixed hed mounted on said support and adapted to receive said mat;
at least two spacer bars disposed on said fixed bed and flanking sald mat;
a deformable movable bed ~uxtaposed with said fixed bed;
main cylinder means including a plurality of main piston-and-cylinder arrangements disposed between said support and said movable bed for displacing said movable bed to compress said mat against said fixed bed;
auxiliary cylinder means including at least two bearing cylinders along with said spacer board and disposed between said movable bed and said support for clamping said movable bed against said spacer bar to effect deformation of said movable bed; and control means including a deformation-measuring device responsive to the deformation of said movable bed for operating said main piston-and-cylinder arrangements to level deformation of said bed and thereby parallel compression of said mat.
In accordance with a second aspect of the invention there is provided a method of operating a platen press for the compression of a particle-board mat to produce particle board, comprising the steps of:
disposing a particle-board mat between a fixed platen and a deformable movable platen of said press and flanking said mat with a pair of spacer bars resting upon said fixed platen;
urging said movable platen along outward edges thereof into bearing contact with said spacer bars, thereby deforming said movable platen between said spacer bars in contact with said mat;
measuring the degree of deformation of said movable platen; and l~Z~7 11689 applying pressure to said movable platen to compress said mat in response to the measurement to level deformation of said movable platen and ensure parallel compression of said mat.
Specific embodiments of the invention will now be described having reference to the accompanying drawings in which :
FIG. 1 is a diagrammatic elevational view of a platen press according to the invention at the beginning of the press-clos-ing operation;
FIG. TA is a detail view, drawn to an enlarged scale, 4 the portion IA of FIGo 1;
FIG. 2 is an elevational view of a portion of the press shown in FIG. 1 upon closing of the press to the statically de-termined position of the movable press bed on the spacer bars; and FIG. 3 is a view similar to FIG. 2 but showing the press in its positlon for parallel pressing.
In the drawing I have shown a single-ievel platen press for ~he compaction of particle-board mats 1 in the manufacture o~
chipboard, fiberboard, asbestos board or the like.
The press comprises a support 2 in the form of a number of spaced-apart portal frames, only one of which has been illustrated but others of which can be provided as shown in U.S. patent 3,860,381. A rigid fixed press bed 3 is mounted on this support and is juxtaposed with a movable press bed 4.
A plurality of worXing cylinder arrangements S are provided symmetrically with respect to a longitudinal vertical medium plane 6 thxough the press.
-l~a ~3~327 More particularly, each of the main cylinder-arrangements 5, of which two are provided in each frame, can include a cylinder proper 5a, a piston 5h axially shiftable in this cyl-inder Sa and a pedestal Sc, bearing upon the respective beam 4a to which the press plate 10 of the movable bed 4 is attached.
Similarly, a plurality of symmetrically disposed auxiliary cylinder arrangements 7 can be provided outwardly of the main cylinders 5. Two such auxiliary cylinder arrangements, each in-cludiny a cylinder proper 7a and a piston 7b can be mounted in each frame.
The hydraulic control for the cylinders 5 is shown at 8 and can include a hydraulic servomechanical system as described in SERVOMECHANISM PRACTICE, McGraw-Hill Book Company, New York, New York, 1960 (pages 390 ff).
Naturally, a retraction system can be provided, if the cylinders are not double-acting, to raise the movable platan into the position shown in FIG. 1, Furthermore, although this cannot be seen from the drawing, each cylinder 5 or 7 represents a row of corresponding cylinders disposed one behind the other along the length of the press.
Furthermore, the press plates 9 and 10 can be heated, e.g. by electrical means of a fluid system.
The press plates 9 and 10 cooperate with spacer bars 11 dis-posed along the longitudinal edges of the plates 9 and 10. Accord-ing to the invention, the cylinders 7 serve as bearing cylindersand apply force to the movable bed 4 in axial alignment with the centerlines 13 of the spacer bars 11.
1132.3Z~
The control arrangement 8 is provided with an input from a deformation ~asuring device such as a strain gauge system 14 (pages 343 ~f. of SERVOMECH~IS~1 P~ACTICE) which measures the deformation of the movable press bed. Pickups for the strain gauge system 14 have been represented diagrammatically at 16.
From the position shown in FIG. 1, the movable bed 4 is brought into contact with the mat 1 and then the bearing cylinders 7 are actuated to bring about contact between the bed 4 and the spacer bars 11 which thereupon support the movable bed in a statically determined starting position. The strain gauge 14 measures the deformation of the platen (FIG. 2) and provides an input to the control system 8 to power the main cylinders 5 to remove the deformation and ensure parallel compression. Further compressing is effected in parallelity (FIG. 3).
Hinges`or pivots 15 are provided between the cylinders 7 and the support 2 on the one hand and the movable bed 4 and the width B of the spacer bars 11 is selected so that the app~ica-tion of the bearing pressure does not cause permanent deforma-tion of the movable bed.
PRESSABLE MATERIAL, ESPECIALLY FOR THE PRODUCTION
OF PARTICLE BOARD, AND A METHOD OF OPERATING SAME
My present invention relates to an apparatus for the compression of mats of pressable material, especially mats of wood, cellulosic or like materials for the production of pressed board. The invention also relates to a method of operating such a press and, more particularly, to improvements in the parallel compression of pressed board, i.e. the formation of pressed board with a high degree of regularity and planarity or parallelity of its surfaces.
In the production of pressed board it is known to provide platen presses or the like in which a mat of a material capable of fusion to form the pressed board is compressed between two planar surfaces, generally forming the bedplate and headplate of a pla~en press.
Typical of the systems provided for this purpose is that of my U.S. patent 3,860,831 and the earlier systems described or referenced in that patent.
113~2~Z7 ~89 The term "pressed board" is gen~rally referred to in its most generic sense to identify hardboard, i.e. material of high structural strength, low flu~d permeability and excellent surface characteristics, as well as to less dense and highly porous boards which may be used as thermal or acoustical insulation, for interior finishing, or the like. The term is generic to any relatively rigid generally flat board structure, forn~ed by compression utiliz-ing both heat and pressure, to bond fibers, chips or dust of wood or some other material, e.g. a cellulosic material, with intrinsic 10 ~ thermally activatable binder or an added binder, the board being pressed from a structure which, for convenience, will be defined as a mat.
The ter~ "mat" is used herein likewise in its most generic and general sense to refer to a layer of more or less coherently interrelated particles and the binder.
The aforementioned publications describe how such materials may be introduced into a platen press and how thP finished board may be carried away for further processing.
It is known to provide a platen press for the compaction of particle board mats, i.e. for the production of chi?board, fiberboard and sawdust board, which comprises a press frame or support structure, a fixed press plate or bed, a movable press plate or bed, and a multiplicity of working cylinder arrangements which are disposed symmetrically with respect to a vertical median longitudinal plane through the press. The working cylinder arrange-ments will each be understood to include at least one cyllnder and at least one piston, either the cylind~r or the piston being con-nected to the press support or frame while the other of these member~
is connected to the movable press plate.
113~2~7 ~89 Such systems have also been provided here~ofore wlth a plurality of auxiliary piston-and-cylinder arrangements which can be used to modify the orientation of the movable press ~ember so as to ensure generally parall,el pressing of the board.
Naturally, control systems can be provided for the hydraulic piston-and-cylinder arrangements.
The movable and stationary press beds are generally formed with pressing plates which can be heated, e.g. electrically or by fluid heating techniques, the movable and/or stationary beds each including, in addition to the resp~ctive press plate, a plurality of beams which generally extend transversely of the longitudinal a~is oE the press and serve as points of attack for the hydraulic cylinder arrangements.
Naturally, for high quality pressed board, it is desirable that the compression be of the parallel type. The term "parallel compression" is used herein to indicate that the upper and lower faces of the pressed board, at least as the latter emerges from the press, are as close to parallel to one another as possible.
Since these surfaces are also usually planar, reference may also be made to plane-paràllel surfaces.
Plane-parallel surfaces of a pressed board indicate that neither surface has bulges which can be considered as deviations from planarity, furthermore the parallel requirement specifies that the board is of uniform thickness throughout its length and breadth.
Obvlously, for plane parallel compression of the pressed--material mat~ it is essential to compensate for any elastic deformation of the pressing beams, the beds or the pressing plates.
1~8 3, ~ z,7 A pressing frame, as here described is intended to include any type of press support commonly in use. For example, the press support may be a post structure carrying the bed and upon which the upper member of the press is mounted, e.g. a headplate, or a row of portal frames spaced apart in the longitudinal dimension of the press. A system of the latter type is shown for the platen press of U S. patent 3,8~0,381.
The movable press member or bed can be either the upper or the lower bed.
The movable press bed is ge~erally lighter than the fixed press bed and, when the deformation of the press beds is con-s~dered, is the more readily deformed member.
~ f parallel compression of the mat and the boards is desired without compensation by the prior-art techniques, ~ne must either resort to extraordinarily massive press beds, încapable of any deformation during the pressing operation, or must accept a certain degree of convex or concave curvature resulting from the distortion of the movable press bed.
It is possible, following the pressing operation, to remove the convex or concave curvat~re in the pressed board by expensive an~ time-consuming shaping, material-removal or like aftertreatments.
The principles here described are applicable to the single-stage or single-level platen presses of the type describPd in the afore-mentioned patent as well as to double-level or two-stage presses as likewise have been illustrated therein. In the latter case, ~89 the fixed press bed is the intermediate bed, the upper and lower plates being movable. me principles are also apDlicable to multilevel presses in which the press plates between the stages are movable. In this case, of course, the parallel compression must be dealt with as a sum so that the individual distortions of the intervening plates as well as the upper or lower movable plate can be compensated. Finally, the system described will be understood to be applicable as well to the compression of asbestos cement plates or boards and the like.
The prior-art apparatus, represented for example in German patent document (open application - Offenlegungsschrift~
DE-OS 15 02 042, is shown as a single-level press. In this apparatus, the working piston-and-cylinder arrangements are disposed outwardly, as seen in plan view, of the longitudinal median plane of the press and their respective points of attack lie inwardly of the spacer bars which are provided between the press plates to establish the thickness of the pressed board to be formed in the press.
The auxiliary piston-and-cylinder arrangements, provided primarily to equalize or compensate for distortion of the movable press plate, are disposed generally in the region of the longi-tudinal vertical median plane of the press. These auxiliary cylinders thus act as compensating cylinder arrangements which are intended to level the aforementioned deformations of the movable press member under the control o a control arrangement or device.
3Z'~
~89 The movable press member, in the operation of the con-ventional apparatus, is inltially displaced by actuating all or individual ones of the compensating cylinder arrange~ents downward-ly until the press plate comes to lie on the mat to be compressed.
During this step, the working cylinders are merely entrained.
The respective pressurizable compartments behind the pistons o these cylinders are, of course, filled with fluid, e.g. from an accumu-lator or sto~age vessel, although an ele~ted pressure is not generated in these compartments during the entrainment phase.
When the press plate contacts the mat, the working cylinders are actuated so that their pistons apply the full pressure to the plate and are driven by the full hydraulic pressure in the compression mode. ~his, of course, forces the upper or movable press plate downwardly to compact the ma-.
As already implied, the working cylinders are disposcd relatively far from the spacer bars. As a consequence, upon com-pression of the mat, depending upon the nature of the material pressed and the height of the layer forming the mat, the movable press plate deforms or bulges to a greater or lesser extent together with the pressing beam.
When the pressing plate of the movable bed engages the spacer bars, the pressure in the working cylinders increases markedly, Pressure-sensing devices respond to this pressure increase and generate a control pulse which cuts o~f the main cylinders and, in some cases, relieves them. By contrast, the compensating cylinders generally remain under the working pressure to compensate for the bulging or deformation of the movable press bed.
1132~7 If the bulge is in the direction of the fixed bed, the corresponding compensating cylinder is relieved. Conversely, if the bulge is in the direction opposite the fixed bed, the compen-sating rylinder may be additionally pressurized. Naturally, the compensating operati~ns must be determined experimentally for each type o mat, for each board-producing program, for the varlous pressure levels and pressing periods operatin~ in the press.
Even with these empirical derivations of the response to be made by the compensating cylinders, one cannot complet~ly exclude significant variations resulting from changes in the nature of the mat or the like. The same applies for the si~nificant variations in the counterpressure generated in the mat and opposing ad~ance of the movable press plate during the pressing operation and resulting from premature hardening of ~he binder or variations in the moisture level in the particle material of the mat under the effect of heat from the heatin~ plates.
As a consequence, the response of the movable press plate to the particular pressing operation cannot always be determined in advance an~ even when determined in advance, is not necessarily constant or reproducible.
As a consequence, the control method of the prior art is extremely complicated and must permit relatively large tolerances.
It is, therefore, practically impossible with the prior-art system to provide plane parallelity of the pressed boards with extremely narrow or small tolerances.
~323~7 ~8 9 Another disadvantage of ~he prior-art system is that signlficant moments are generated betr~een the main cylinders and the spacer bars in the press plates so that the press plates can impart to the boards a substantially corrugated surface which must be sanded down or otherwise treated. This is especially the case when the movable press bed is ma~e relatively light to save material and hence is especially bendable.
Reference may be had to German patent document (printed application - Auslegeschrif~ DE-AS 17 03 297 in which si~ilar problems may arise although spacer bars are avoided and the working cylinders or main cylinders are provided at the outer edges of the movable press bed or plate.
Another system, represented by German patent document (utility model - Gebrauchsmuster) DE - GBM lg 24 142 in which the main cylinder arrangements are disposed along the edge of the movable press bed and the press plates are so arranged that these main cylinders lie directly above the spacer bars. This, however, precludes a proper compensating operation to cvercome deformation of the movable press bed or plate.
It is the principal object of the present disclosure to provide a press, particularly a platen press, for the pressing of particle-board mats whereby the finished product can be of high planar parallelity and with limited tolerances, while avoiding disadvantages of earlier systems as enumerated above.
1~L3;2327 68 ~
It is another object o~ ~is disclosure to provide an improved method of operating a platen~press so as to eliminate the drawbacks of the earlier systems described.
Still another object of the presént disclosure is to provide a press for the purposes described in which a movable press bed can be given a statically determined position for each pressing operation so that compensation of the deformation of ~he press plate can be effected simply and read;ly.
Yet another object of the disclosure is to provide an improved method of pressing mats to produce pressed board of high plane parallelity.
These objects and others which will become apparent here-inafter are attained, in a platen press for the compaction of particle-board mats which comprises a fixed plate, a movable plate, main fluid-operated cylinders ef-fective to generate the pressure required to convert the mat into pressed board and acting upon the movable plate.
The mat is flanked by spacer bars which rest upon the fixed plate and the auxiliary cylinders are formed as bearing cylinders,positioned over the spacer bars, so as to press the movable plate against these bars and thereby retain the movable plate against these bars during the subsequent operation of the main cylinders.
Means is pro-vided to respond to deformation of the movable plate, such means _9_ 113~3Z7 6~
forming part of the control system for the main cylinders so that the latter are actuated in re~ponse to deformation to the movable plate to level such deformation and ensure parallel compression of the mat.
During this latter operative step, the movable plate acts as a beam supported at two spaced-apart l~tions of pedestals, corresponding to the spacer bars against which the beam or platen is held.
The term "plate" has been used above to refer to the movable p~aten and thus is utilized in its most general sense to mean the movable press member which compacts the mat and which can be heated as described previously. Naturally this movable platen can include any beams or bed structure to which the cylinders are connected and an~ plate or the li~e attached to such bed structures or actual engagement with the mat and the spacer bar. The bed structure may be formed by anothex plate or by an array of girders, crossbeams, spars or the li~e. Since the spacer bars are dis-posed outwardly of the ~ats to flank the latter, the auxiliary or bearing cylinders likewise are disposed outwardly of the main cylinders.
The term "cy-linders" as used above and subsequently herein is intended to refer to fluid-operated ram or jack structureS
which may also be described as piston-and-cylinder arrangements.
In such arrangements, a piston is telescopically slidable in a cylinder chamber or cylinder proper, being displaced by pres-surization of a compartment behind the piston, generally with a liquid medium. While the cylinder prefereably bears upon a fixed support structure, e.g. a portal frame as described above and the piston then acts upon the movable press bed, a reverse ~23~
kinematic constructi~n is also possible whereby the piston is affixed to the stationary support whi~e the cylinder acts upon the movable bed.
Thus the system disclosed dlstinguishes from the state of the art mentioned presiously by utilizing the auxiliary piston-and-cylinder arrangements as bearing cylinder units which apply force directly to the mcvable bed in line with the spacer bars to clamp the spacer bar between the bearing 10 cylinder and the fixed bed of the press, while the control means for the main cylinders includes the deformation-measuring device which reeponds to deforma~ion of the movable press bed and con-trols the main cylinders in response to the measured deformation to displace the movable bed so as to level the deformat~on and 15 ensure parallel compression.
From elementary statistics, the statically determined problem in analy~ing the response of beams on two supports is well know. Correspondingly, a plate of platen which rests upon two spaced-apart supports and is held thereagainst at its edges, 20 presents a statically determined problem.
Thus, the vress plate of the movable press bed is initially brought to bear upon the mat to be compressed, either with the bearing cylinder ar-rangements or with the main cylinder arrangements or both~
Generally it is more convenient to advance the movable bed with the bearing cylinders and to simply entrain the working or main cylinders with the movement of this bed.
Z~327 .
Next, the bearing cylinders forcibly apply the ~ovable bed to the spacers to form the statically determined structure of a plate mounted upon the supports in the manner described. In general this wlll result in a convex deformati~n of the movable S press bed and its plate,which deformation can be readily measur-ed and determined.
When reference is made to deformation measurement of the movable bed it should be understood that the deformation measure-ment can be made upon the press beams or upon the plate proper since deformation of the one is followed or produces deformation of the other.
The operation of the main cylinders is so controlled that this deformation is compensated and hence a parallel compression is applied to the mat which is automatically maintained during any further compression-In order to exclude the tapering of the pressed board duringthe pressing to one edge, a preferred embodiment of the invention provides that the auxiliary or bearing cylinders are pivotally connected to the support and to the movable bed. This, of course, means that the piston is hinged to either the frame or the movable bed while the cylinder proper is hinged to the other.
According to another feature, the spacer bars can have a width such that the bearing force, i.e. the force ap-plied by the bearing cylinders, is spread by the bars and perma-nent (plastic or inelastic) deformation of the beds and the re-spective plates of the press are avoided.
1~32;3~7 116~
Indeed, German patent document (printed application- Aus-legeschrift) DE-AS 16 53 187 describes relatively wide spacer bars, although not in an equivalent relationship to bearing cylinders or the liXe.
~he movable press bed herein described is advan-tageously comparatively light and preferably is so designed as to be elastically deformable but not compressible under the standard pressing forces which are used. Naturally, this means that both the beams of the movable bed and the press plate there-of should be elastically deformable. This guarantees light--weight construction of the movable platen and makes the system more responsive to the control operation described above.
While the deformation measurement can be effected by any conventional means it is preferred to provide the deformation--measuring device as a strain gauge whose strips are mounted upon the beams or the plates of the movable bed.
-The output of the strain gauge can be used by applying it to a conventional control circuit to operate the hydraulic system by techniques well known in the control arts.
The system here described has the advantage that it utilizes a statically determined position for the press plate at the beginning of the deformation-compensation operation and hence also ma~es use of statically determined responses of the disadvantages described previously. A relatively simple control system can be provided for this purpose~
.
i~3;~2~
More particularly in accordance with a first aspect of the invention there is provided a platen press for the compression of a mat to produce a board, comprising:
a support;
a rigid fixed hed mounted on said support and adapted to receive said mat;
at least two spacer bars disposed on said fixed bed and flanking sald mat;
a deformable movable bed ~uxtaposed with said fixed bed;
main cylinder means including a plurality of main piston-and-cylinder arrangements disposed between said support and said movable bed for displacing said movable bed to compress said mat against said fixed bed;
auxiliary cylinder means including at least two bearing cylinders along with said spacer board and disposed between said movable bed and said support for clamping said movable bed against said spacer bar to effect deformation of said movable bed; and control means including a deformation-measuring device responsive to the deformation of said movable bed for operating said main piston-and-cylinder arrangements to level deformation of said bed and thereby parallel compression of said mat.
In accordance with a second aspect of the invention there is provided a method of operating a platen press for the compression of a particle-board mat to produce particle board, comprising the steps of:
disposing a particle-board mat between a fixed platen and a deformable movable platen of said press and flanking said mat with a pair of spacer bars resting upon said fixed platen;
urging said movable platen along outward edges thereof into bearing contact with said spacer bars, thereby deforming said movable platen between said spacer bars in contact with said mat;
measuring the degree of deformation of said movable platen; and l~Z~7 11689 applying pressure to said movable platen to compress said mat in response to the measurement to level deformation of said movable platen and ensure parallel compression of said mat.
Specific embodiments of the invention will now be described having reference to the accompanying drawings in which :
FIG. 1 is a diagrammatic elevational view of a platen press according to the invention at the beginning of the press-clos-ing operation;
FIG. TA is a detail view, drawn to an enlarged scale, 4 the portion IA of FIGo 1;
FIG. 2 is an elevational view of a portion of the press shown in FIG. 1 upon closing of the press to the statically de-termined position of the movable press bed on the spacer bars; and FIG. 3 is a view similar to FIG. 2 but showing the press in its positlon for parallel pressing.
In the drawing I have shown a single-ievel platen press for ~he compaction of particle-board mats 1 in the manufacture o~
chipboard, fiberboard, asbestos board or the like.
The press comprises a support 2 in the form of a number of spaced-apart portal frames, only one of which has been illustrated but others of which can be provided as shown in U.S. patent 3,860,381. A rigid fixed press bed 3 is mounted on this support and is juxtaposed with a movable press bed 4.
A plurality of worXing cylinder arrangements S are provided symmetrically with respect to a longitudinal vertical medium plane 6 thxough the press.
-l~a ~3~327 More particularly, each of the main cylinder-arrangements 5, of which two are provided in each frame, can include a cylinder proper 5a, a piston 5h axially shiftable in this cyl-inder Sa and a pedestal Sc, bearing upon the respective beam 4a to which the press plate 10 of the movable bed 4 is attached.
Similarly, a plurality of symmetrically disposed auxiliary cylinder arrangements 7 can be provided outwardly of the main cylinders 5. Two such auxiliary cylinder arrangements, each in-cludiny a cylinder proper 7a and a piston 7b can be mounted in each frame.
The hydraulic control for the cylinders 5 is shown at 8 and can include a hydraulic servomechanical system as described in SERVOMECHANISM PRACTICE, McGraw-Hill Book Company, New York, New York, 1960 (pages 390 ff).
Naturally, a retraction system can be provided, if the cylinders are not double-acting, to raise the movable platan into the position shown in FIG. 1, Furthermore, although this cannot be seen from the drawing, each cylinder 5 or 7 represents a row of corresponding cylinders disposed one behind the other along the length of the press.
Furthermore, the press plates 9 and 10 can be heated, e.g. by electrical means of a fluid system.
The press plates 9 and 10 cooperate with spacer bars 11 dis-posed along the longitudinal edges of the plates 9 and 10. Accord-ing to the invention, the cylinders 7 serve as bearing cylindersand apply force to the movable bed 4 in axial alignment with the centerlines 13 of the spacer bars 11.
1132.3Z~
The control arrangement 8 is provided with an input from a deformation ~asuring device such as a strain gauge system 14 (pages 343 ~f. of SERVOMECH~IS~1 P~ACTICE) which measures the deformation of the movable press bed. Pickups for the strain gauge system 14 have been represented diagrammatically at 16.
From the position shown in FIG. 1, the movable bed 4 is brought into contact with the mat 1 and then the bearing cylinders 7 are actuated to bring about contact between the bed 4 and the spacer bars 11 which thereupon support the movable bed in a statically determined starting position. The strain gauge 14 measures the deformation of the platen (FIG. 2) and provides an input to the control system 8 to power the main cylinders 5 to remove the deformation and ensure parallel compression. Further compressing is effected in parallelity (FIG. 3).
Hinges`or pivots 15 are provided between the cylinders 7 and the support 2 on the one hand and the movable bed 4 and the width B of the spacer bars 11 is selected so that the app~ica-tion of the bearing pressure does not cause permanent deforma-tion of the movable bed.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A platen press for the compression of a mat to pro-duce a board, comprising:
a support;
a rigid fixed bed mounted on said support and adapted to receive said mat;
at least two spacer bars disposed on said fixed bed and flanking said mat;
a deformable movable bed juxtaposed with said fixed bed;
main cylinder means including a plurality of main piston--and-cylinder arrangements disposed between said support and said movable bed for displacing said movable bed to compress said mat against said fixed bed;
auxiliary cylinder means including at least two bearing cylinders along with said spacer board and disposed between said movable bed and said support for clamping said movable bed against said spacer bar to effect deformation of said movable bed;
and control means including a deformation-measuring device responsive to the deformation of said movable bed for operating said main piston--and-cylinder arrangements to level deformation of said bed and thereby parallel compression of said mat.
a support;
a rigid fixed bed mounted on said support and adapted to receive said mat;
at least two spacer bars disposed on said fixed bed and flanking said mat;
a deformable movable bed juxtaposed with said fixed bed;
main cylinder means including a plurality of main piston--and-cylinder arrangements disposed between said support and said movable bed for displacing said movable bed to compress said mat against said fixed bed;
auxiliary cylinder means including at least two bearing cylinders along with said spacer board and disposed between said movable bed and said support for clamping said movable bed against said spacer bar to effect deformation of said movable bed;
and control means including a deformation-measuring device responsive to the deformation of said movable bed for operating said main piston--and-cylinder arrangements to level deformation of said bed and thereby parallel compression of said mat.
2. The press defined in claim 1, further comprising pivot means connecting said bearing cylinders to said support and to said movable bed respectively.
3. The press defined in claim 1 wherein said spacer bars have a width selected to prevent permanent deformation of said movable bed upon the clamping of said movable bed there-against.
4. The press defined in claim 1, claim 2, or claim 3 wherein said movable bed is constructed and arranged so as to be elastically deformable by said mat upon the pressing of said bed against said spacer bars by said bearing cylinder.
5. The press defined in claim 1, claim 2 or claim 3 wherein said device includes a strain gauge.
6. A method of operating a platen press for the com-pression of a particle-board mat to produce particle board, comprising the steps of:
disposing a particle-board mat between a fixed platen and a deformable movable platen of said press and flanking said mat with a pair of spacer bars resting upon said fixed platen;
urging said movable platen along outward edges thereof into bearing contact with said spacer bars, thereby deforming said movable platen between said spacer bars in contact with said mat;
measuring the degree of deformation of said movable platen; and applying pressure to said movable platen to compress said mat in response to the measurement to level deformation of said movable platen and ensure parallel compression of said mat.
disposing a particle-board mat between a fixed platen and a deformable movable platen of said press and flanking said mat with a pair of spacer bars resting upon said fixed platen;
urging said movable platen along outward edges thereof into bearing contact with said spacer bars, thereby deforming said movable platen between said spacer bars in contact with said mat;
measuring the degree of deformation of said movable platen; and applying pressure to said movable platen to compress said mat in response to the measurement to level deformation of said movable platen and ensure parallel compression of said mat.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2906422.0-15 | 1979-02-20 | ||
| DE2906422A DE2906422C2 (en) | 1979-02-20 | 1979-02-20 | Press for the pressing of Preßgutmatten in the production of chipboard, fibreboard and the like. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1132327A true CA1132327A (en) | 1982-09-28 |
Family
ID=6063373
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA345,926A Expired CA1132327A (en) | 1979-02-20 | 1980-02-19 | Apparatus for the pressing of mats of pressable material, especially for the production of particle board and a method of operating same |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS55156043A (en) |
| CA (1) | CA1132327A (en) |
| DE (1) | DE2906422C2 (en) |
| FI (1) | FI793503A (en) |
| FR (1) | FR2449528A1 (en) |
| IT (1) | IT1127677B (en) |
| PL (1) | PL121366B1 (en) |
| SE (1) | SE8000785L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3101616C2 (en) * | 1981-01-20 | 1983-02-10 | G. Siempelkamp Gmbh & Co, 4150 Krefeld | Holmverformungsmeßeinrichtung for plate presses for the production of chipboard, fiberboard, laminate panels and the like. |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1653187A1 (en) * | 1951-01-28 | 1971-09-09 | Dieffenbacher Gmbh Maschf | Spacer element for hot plate presses |
| DE1502142A1 (en) * | 1964-11-04 | 1969-05-29 | Baehre Metallwerk Kg | Process for pressing plates and a press for carrying out the process |
| DE1924142U (en) * | 1965-07-27 | 1965-09-23 | Dieffenbacher Gmbh Maschf | HYDRAULIC PRESS. |
| FR1586274A (en) * | 1967-10-10 | 1970-02-13 | ||
| DE1703297A1 (en) * | 1968-04-29 | 1972-02-17 | Freudenberg Carl Fa | Hot plate press with self-compensating cylinder piston arrangements |
| DE1777088A1 (en) * | 1968-09-04 | 1971-04-01 | Schlieper Guenter | Hydraulic construction with self-regulating compensation piston |
-
1979
- 1979-02-20 DE DE2906422A patent/DE2906422C2/en not_active Expired
- 1979-11-08 FI FI793503A patent/FI793503A/en not_active Application Discontinuation
- 1979-11-29 IT IT27700/79A patent/IT1127677B/en active
- 1979-12-20 PL PL1979220563A patent/PL121366B1/en unknown
-
1980
- 1980-01-31 SE SE8000785A patent/SE8000785L/en not_active Application Discontinuation
- 1980-02-18 FR FR8003482A patent/FR2449528A1/en not_active Withdrawn
- 1980-02-18 JP JP1795280A patent/JPS55156043A/en active Granted
- 1980-02-19 CA CA345,926A patent/CA1132327A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| SE8000785L (en) | 1980-08-21 |
| JPS5654222B2 (en) | 1981-12-24 |
| FI793503A (en) | 1980-08-21 |
| JPS55156043A (en) | 1980-12-04 |
| IT7927700A0 (en) | 1979-11-29 |
| DE2906422A1 (en) | 1980-08-21 |
| PL121366B1 (en) | 1982-04-30 |
| DE2906422C2 (en) | 1983-12-08 |
| FR2449528A1 (en) | 1980-09-19 |
| PL220563A1 (en) | 1980-09-22 |
| IT1127677B (en) | 1986-05-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4289467A (en) | Apparatus for the pressing of mats of pressable material, especially for the production of particleboard | |
| US4098109A (en) | Bending press or similar machine tool | |
| US4711111A (en) | Forming press mat utilizes trays formed of thin bottom plates and separate annular frames | |
| US4311091A (en) | Rapid-separation mounting arrangement for rollers of a calendering machine | |
| CA1132327A (en) | Apparatus for the pressing of mats of pressable material, especially for the production of particle board and a method of operating same | |
| US4128376A (en) | Pressing arrangement for compressing ceramic and refractory materials into tile preforms | |
| US4909719A (en) | Heated platen press of window frame-like construction | |
| US3205551A (en) | Double toggle-lever press | |
| JPH1067004A (en) | Production of chipboard | |
| JPS592569B2 (en) | flat plate bending press | |
| US3526188A (en) | Arrangement in single storey presses for chipboard,fibreboard or the like | |
| KR102218090B1 (en) | Presser using gravity | |
| US4504207A (en) | Pressing apparatus for making particleboard | |
| GB664425A (en) | Improvements in and relating to method and apparatus for making laminated articles | |
| US3511177A (en) | Presses | |
| JPS6334753Y2 (en) | ||
| JPH0239622Y2 (en) | ||
| CN220126152U (en) | Outer frame for hexahedral top press | |
| RU2226152C2 (en) | Press for cardboard production | |
| CN220742409U (en) | Honeycomb composite board cold press | |
| DE19633289C1 (en) | Heated press for production of plastic coated thin laminated panels | |
| SU1810220A1 (en) | Cardboard pressing machine | |
| CN220162149U (en) | Quick pressing mechanism of grinding machine | |
| CN211744546U (en) | Scanner | |
| KR950009212Y1 (en) | Pressing device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |