Patent Publication Number: US-4370112-A

Title: Method and apparatus for molding articles from agglomerated particles

Description:
This is a division of application Ser. No. 756,000 filed Jan. 3, 1977, now U.S. Pat. No. 4,165,353 issued Aug. 21, 1979. 
    
    
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a method of molding articles from agglomerated particles and especially for molding the articles from agglomerated wood particles, preferably particles which are elongated in the direction of the fiber of which they are composed. 
     The invention also relates to a device for carrying out this process. 
     There is a known process for manufacturing articles from agglomerated wooden particles with a small quantity of binder or resin which process consists in preparing batches of particles impregnated with binder, delivering these batches to a press having a compression chamber and a plurality of pistons acting in different directions which compress the particles of the batch, said chamber having an open face which is temporarily blocked by an intermediate mold which receives the compressed batch, after which the mold with its batch is brought to the rear end of a row of intermediate molds, the molds being so positioned that the rear surface of the preceding mold compresses the material contained in the succeeding mold while polymerization is carried out in the entire row of molds. Each time that a new mold is brought to the rear end of the row, the first mold of the row is evacuated and the article removed from the mold. 
     This process is particularly appropriate to the rapid manufacture of objects of relatively small size, especially elongated wooden particles, since it permits very rapid operation of the press itself while leaving all the time necessary for setting or polymerization. 
     The present invention proposes to improve this process so as to permit simplification of the necessary apparatus in order to facilitate complete automation of the apparatus and assure the permanence of the necessary pressures in a simple way even if these have a high value, without the consumption of large quantities of energy. 
     It is an object of the present invention to provide a process for manufacturing articles from agglomerated particles and particularly agglomerated wooden particles, using a small quantity of binder, in which process batches of particles are prepared, delivered one by one to a press having a preferably vertical chamber, and one or more pistons capable of penetrating into the chamber to produce the compression. The chamber has an open face against which one temporarily maintains the front face of an intermediate mold destined to receive the article and a rear face which may or may not bear directly on the front face of the article. Compression is effected and then one brings the intermediate mold containing its article to the rear end of a row of molds and holds the articles in the molds of the row under pressure during setting or polymerization. The process is characterized by the fact that in order to put the last intermediate mold in place the row of molds is held in position, said intermediate mold is pushed against the last intermediate mold of the row by exerting a sufficient pressure thereagainst, and the last mold is positively attached to the preceding mold. Preferably the first mold is also removed from the row after having separated it from the second. 
     Preferably the row of molds subjected to polymerization is spaced from the press and means independent of the press are used to insure the compression of the material during the attachment of the last mold. 
     In an advantageous manner this compression is brought about by pushing the row of molds backwardly against abutment means and the recoil movement thus created is used to eliminate the connection between the first and second molds. 
     It is also an object of the invention to provide a device for carrying out this process in an installation comprising a press, means for feeding the press, and a recycling circuit for a plurality of intermediate molds, said circuit including means for forming a row of molds in which the material is maintained under pressure during polymerization said device being characterized by the fact that each mold has attaching means holding it in contact with the preceding mold, means being provided on the one hand to actuate these attaching means and to initiate attachment of the last mold of the row to the preceding mold and, on the other hand, to disconnect the first mold from the row with the succeeding mold, said device comprising also means for temporarily compressing the last mold against the row of molds. 
     Preferably said connecting or attaching means comprise one or more pivotally attached hooks carried by one of the molds and adapted to penetrate into a complementary part of an adjacent mold, and in this case the means for bringing about the attachment and detachment may advantageously comprise jacks, abutments, or ramps cooperating with the hooks. 
     The device according to the invention preferably includes, mounted on a frame, means for supporting a straight row of molds, a power jack mounted at the front of the frame to push the piston of the jack backwardly, an abutment situated at the rear of the frame to receive the rear face of the last mold, a second less powerful jack for pushing the row of molds forwardly, the frame also comprising different means for attaching and detaching the molds. 
     In an advantageous manner, the power jack may be adapted to travel along a substantial path at low pressure to push back the row of molds and then travel over a final path providing high pressure compression. 
     In an advantageous manner, the piston of the jack may have gripping means capable of gripping the first mold of the row to move this first mold of the column forwardly during the return movement of the jack toward the front. In this embodiment means are provided to cause the detachment of the first mold from the second during the movement of the row toward the rear under the pressure of the jack. In this case one may advantageously provide other gripping means cooperating for example with the free hook of the last mold of the row to hold the row stationary during the return movement to the front of the power jack and surely separate the first mold from the rest of the row. 
     In an advantageous manner the means for assuring the attachment and detachment may cooperate with rollers carried by the hooks to permit pivotal movement of the hooks about their axes. 
     The intermediate molds used may be of any type having a front part receiving the molded object and a rear part adapted to cooperate with the front part of the next mold to receive the front surface of the object but the device may advantageously be applied to the circulation of complex molds, for example in an installation making it possible to mold crates for vegetables or fruits in a single operation. Such intermediate molds advantageously comprise an outer cage and an inner core capable of being pushed through the chamber of the press to emerge before the front of the cage, the material being then compressed about the core and pushed with the core, into the cage. 
     In such an embodiment the device according to the invention may still comprise, downstream of the row, mold-emptying means comprising, for example, a jack capable of pushing, and preferably of drawing back, the core toward the outside of the cage and article gripping means fixed to the other side of the mold to grip the article so that during the return of the core into the cage the article is released. 
    
    
     Other advantages and characteristics of the invention will appear from a reading of the following description, given purely by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic view of an installation comprising the device according to the invention; 
     FIG. 2 is a top plan view of a part of the device according to the invention; 
     FIG. 3 is an elevational view of the part shown in FIG. 2; 
     FIG. 4 is a top plan view of the piston of the power jack gripping an intermediate mold; 
     FIG. 5 is a top plan view of a row of molds with the means for attaching them to each other; 
     FIGS. 6-9 are schematic views illustrating different stages of the process according to the invention; 
     FIG. 10 is a top plan view of a mold emptying station according to the invention; and 
     FIG. 11 is a front view of this station. 
    
    
     Referring first to FIG. 1, the installation comprises a press schematically indicated by reference numeral 1, for example of the type described in French Certificate of Addition No. 95386. This press makes it possible to successively supply a plurality of molds 2 the inner configuration of which is shown in greater detail on FIG. 10. The mold represented on FIG. 10 has a cage having substantially the form of a parallelopiped open at one of its ends. In this cage a core 3 can slide. The front face 4 of this core corresponds to the inner face of a vegetable crate 5. When the core has entered into the cage, it occupies the position shown in broken lines and it will be understood that, in this position, there is, toward the front, between the four internal lateral faces of the cage and the external lateral faces of the core 3 a space sufficient to contain the lateral walls 6 of the crate. 
     The different molds 2, only one of which is shown on FIG. 1, circulate along a closed circuit comprising a first pair of rails 7 permitting translational movement of the mold 2 in the press 1, a second pair of rails permitting movement of the mold 2 perpendicularly to the rails 7, a third pair of rails 9 parallel to the rails 7 and passing a mold-emptying station, and a fourth pair of rails 11 to return the mold to the rails 7. 
     The row of molds rests during the polymerization on the pair of rails 8 and FIG. 1 shows schematically at the rear end of the rails 8 an abutment 12, and at the front end of the rails 8 the piston of a hydraulic jack carrying a plate 13. 
     Referring now to FIGS. 2 and 3 these figures show in a more detailed manner the part of the path of travel which takes place over the rails 8, on which polymerization takes place. 
     The device comprises at this level a strong frame comprising particularly the longitudinal members 14 and transverse members 15. At the rear end, behind the rails 8, is the abutment 12. The frame has at its front part a jack 16 having a very high power, the rod 17 of which supports the plate 13 which is seen in detail on FIG. 4. The device also comprises, beneath the rails 8, a weaker jack 18 the rod 19 of which is connected to a carriage 20 sliding on a rail 21 and having a movable catch 22. Finally the figure shows that the head 13, by reason of its weight, is supported by a carriage 23 which slides on a short rail 24. Moreover, the plate 13 has two gripping hooks 25 capable of pivoting about vertical axes when actuated by jacks 26 carried by the head 13. 
     Referring more particularly to FIG. 5 this shows that each mold has a lateral hook 27 capable of pivoting about vertical axes and having a projecting arm with a roller 28 while the arm which carries the hook itself has a roller 29. These hooks are capable of catching behind extensions 30 carried at each side by the upper part of the mold so that when these hooks are in place the two adjacent molds are firmly held against each other. 
     Means for attaching the hooks to or detaching them from the molds comprise firstly, on opposite sides of the rails 8, hooking arms 31 capable of being driven by a pivotal jack 32 to act under the pressure of the jack against the roller 29 to urge the hook 27 into contact with the rear face of the extension 30. These means also comprise, on opposite sides of the row, a rail 33 which prevents inopportune opening of the hook 27 bearing against the extension 30. Finally on opposite sides of the rail 8 are catches 34 movable about a horizontal axis, these catches being capable of being swung out of the way when the mold 2 travels forwardly. When they return to their rest position they resist the return to the rear of the hooks of the mold and if this return movement to the rear continues the catches 34 immobilized against their abutments 35 act on the rollers 29 to open the hook and cause detachment. 
     Finally at the rear part there is a hooking arm 36 capable of pivoting about a pin 37 under the influence of a suitable jack (not shown). This hooking arm 36 is capable of gripping the hook 27 when the latter is in open position to prevent forward movement of the mold 2. 
     The operation, which is best shown on FIGS. 6-9 is as follows. While a mold 2d is positioned at the level of the press 1, three molds 2a, 2b, 2c are situated on the rails 8 and undergoing polymerization. The three molds 2a, 2b, 2c are attached to each other and are situated in the position shown on FIGS. 6 and 7, that is to say, with the mold 2a  resting against the face of the plate 13, the jack 16 being in retracted position. There is thus a large space between the rear face of the mold 2c and the abutment 12. When the mold 2d has received the agglomerated article, it is displaced the length of the rails 7 so as to come into position above the rails 8 in the position shown in FIGS. 6 and 7. In this position this mold 2d is slightly spaced from the abutment 12. The jack 16 is then actuated and in a first rapid path of travel at low pressure the plate 13 drives the three molds 2a, 2b, 2c toward the rear in the direction of the arrow F, into contact with the mold 2d and it will be understood that the rear part of the mold 2c comes into contact with the front surface of the material contained in the mold 2d. This pressure brings the rear surface of the mold 2d into contact with the abutment 12 as shown on FIG. 8 and at this moment the jack is placed under high pressure and presses the mold 2c against the mold 2d while compressing the material contained inside the mold 2d. 
     The molds 2c and 2d being thus in direct contact, the jack 32 is actuated and the hooks 27 of the mold 2c are positioned against the extension 30 of the mold 2d which is thus locked in place. Moreover, during the movement provoked by the jack moving toward the rear, the hook 27 of the mold 2a is brought by its roller 29 into abutment against the movable catches 34 as may be seen on FIG. 5 and the catch 34 opens the hook of the mold 2a, which is no longer attached to the mold 2b, but is urged against it by the pressure of the jack. Simultaneously the hooks 25 of the plate 13 are brought into place against the projections 30 of the mold 2a. During this time the hooks 27 of the mold 2b are prevented from opening by the presence of the corresponding rails 33. 
     Finally the jack which controls the hooking arm 36 is actuated and this hooking arm reaches the position shown on FIG. 5. 
     From the position on FIG. 8 one now reverses the direction of movement of the jack 16 which moves rapidly at low pressure toward the front. In this return movement the plate 13 only drives the mold 2a through the gripping hooks 25 since the three molds 2b, 2c, 2d are locked together. Moreover the mold 2d is hooked to the arm 36 and thus cannot move when the mold 2a is separated from the adjacent mold and returned to the front. At this moment the arm 25 separates and the mold 2a is removed on the rails 9 to be brought to the mold-emptying station 10. The jack 18 is then actuated. This jack is in the position shown on FIG. 3 and the catch 22 which bears against a suitable part of the mold 2c drives the column formed by the molds 2b, 2c, 2d frontward until the front face of the mold 2b comes into contact with the plate 13 in the position shown for the mold 2a on FIG. 6. A new mold may then be brought in front of the abutment 12 and this cycle is recommenced. 
     Please refer now to FIGS. 10 and 11. 
     The mold 2a which has been brought to the station 10 is immobilized on the rails 9. It is then opposite a transverse jack 36 the rod of which carries a magnetic head 37. When the jack 36 is actuated, the head 37 penetrates through an orifice located in the front face of the cage of the mold to bear against the core 3 which, from its internal position shown in broken lines, is returned to an emerging position shown in solid lines. The core brings with it the crate 5 and when the core has arrived in its advanced position two pivoting arms 38 are brought toward each other by a pivotally mounted jack 39 said arms carrying vertical bars 40 which come into position against the lateral vertical faces of the core behind the sides of the cage 6. The jack 36 is then actuated in the opposite direction and the magnetic head 37 returns the core to the inside of the cage of the mold while the arms 38 with their bars 40 prevent the crate from following this movement and the crate is then removed from the mold and may be evacuated. 
     Of course the invention is not limited to the particular embodiment described and various modifications or variations thereof may be made. 
     Moreover, it is obvious that instead of using rails on which the intermediate molds roll, through intermediate rollers, other means of transport such as belts or carriages may be used. 
     It will also be understood that the polymerization of the molds when they are on the rails 8 in a row hooked to each other may be carried out by various means, such for example as a heating tunnel, or by means of direct resistances incorporated in the various intermediate molds.