US3413395A - Method of making pressed chip plates - Google Patents

Description

Nov. 26, 1968 SCHNITZLER ET AL 3,413,395

METHOD OF MAKING PRESSED cm? PLATES Filed July 12, 1966 10a l N V E NTORS:

Erwin SCHNITZLER y Ulrich SCHNITZLER 11 2. 0.

Attorney United States Patent M 3,413,395 METHOD OF MAKING PRESSED CHIP PLATES Erwin Schnitzler, Kopernikusstr. 16, and Ulrich Schnitzler, Albring 10, both of Karlsruhe-West, Germany Continuation-impart of application Ser. No. 392,803, Aug. 28, 1964. This application July 12, 1966, Ser. No. 564,675 Claims priority, application Germany, Dec. 30, 1965, Sch 38,269 2 Claims. (Cl. 264-120) ABSTRACT OF THE DISCLOSURE A process and a press for fabricating compressed plates out of precut blanks comprising shavings or chips and a known binding or cementing material.

The press includes an upper and lower heated punch and a pair of insulating plates which can be selectively moved between said upper and lower punch.

The process comprises the following steps:

The pre-pressing of a blank between said pair of insulating plates after the latter together with the blank have been positioned between said upper and lower punch. The lower insulating plate may also function as a transport plate for the blank.

Opening the press after the pre-pressing has been completed and removing the pair of insulating plates while leaving the pre-pressed blank on the lower punch.

Closing the press and conventionally compressing the pre-pressed blank.

This is a continuation-in-part application of our copending patent application Ser. No. 392,803, filed Aug. 28, 1964 and now abandoned.

This invention is generally related to an improved method and means for fabricating compressed plates out of precut blanks of shavings or chips. Such blanks are generally formed and held together by means of known binding or cementing material and are, in a first process step, prepressed with the application of little or no external heat application. This is accomplished by inserting between the blank and the press punches a pair of insulating plates during said first process step. Thereafter, the prepressed blank is pressed to its final compressed shape between two preheated punches of a heated press.

In the known processes for this type of pressing operation the shavings or chips are sieved, strained or poured onto a conveyor means in predetermined quantities, i.e. a transport conveyor plate. The blanks are then, with or without pre-pressing, introduced together with the transport plate into the heated press where they are pressed to their final shape. In the aforedescribed known process the transport plates leave the heated press only at the end of the compression process, and then only together with the finished blank.

It is further known to prepress the precut blanks under high compression pressure but without the application of heat. After prepressing, the blank is transported to a second heated press where the blank is compressed into its final shape with the application of heat but without the concomitant transport plate. The aforedescribed process of the prior art has the drawback of requiring two separate press installations. In particular, the press arrangement is relatively large and bulky. Consequently, the additional cost of installation, operation and maintenance becomes quite significant, in particular, in smaller press arrangements of this type.

It is a general object of this invention to provide an improved method for manufacturing composition plates of compressed shavings or chips which requires only a single press installation.

3,413,395 Patented Nov. 26, 1968 It is another general object of this invention to provide an improved pressing machine for compressing composition plates of shavings or chips which dispenses with the usual prepressing installations, thereby considerably reducing the overall dimensions and cost of the machine.

It is another object of this invention to provide means in the machine for preventing the adherence of the chips and shavings to the insulating plates and to facilitate the relatively frictionless removal therefrom.

It is a more specific object of this invention to provide an improved pressing machine in which the active surface of the insulating plates are covered with a layer of material resistant to adhesion so as to prevent the adherence of the blank to the insulating plates after the prepressing thereof.

It is still another specific object of this invention to provide an improved pressing machine, in which the upper insulating plate is movably mounted on supporting rails but in which the upper and lower insulating plates are operatively connected to different coupling means, so that they are movable independently from each other, said pressing machine being further provided with suction cleaning means movably mounted on said rail arrangement.

In the machine and method of our invention the prepressing and fin-al pressing take place between the same punches of the press. A heat insulating plate is, however, placed between each punch and the blank prior to the prepressing process. These insulating plates prevent the transfer of heat from the press into the blank, which is necessary to avoid the hardening of the cementing or binding material of the composition before the blank has been sufficiently compacted. We have for this purpose provided a pair of insulating plates in our novel machine, which are operatively mounted on a rail arrangement and are removed from between the punches prior to the final compression of the blank.

In the method of our invention, in which the prepressing step takes place in the same press as the final compression step, it is important to avoid the adherence of the shavings or chips to the active surfaces of the insulating plates or the heated press punches because (a) an adherence to either the heated press punches or the insulating plates can cause a malfunction of the entire press which, in particular with respect to the heated press punches, is difficult and costly to eliminate and (b) the prepressed blank must be easily deposited between the press punches, that is to say it must be easily slid 01f the insulating plate.

We have found that the adherence of shavings or chips which have been treated with synthetic resin adhesives can be improved, or the splitting off of portions of the prepressed blanks can be effectively reduced or eliminated, by providing the surfaces facing the blank with a coating that is adherence resistant with respect to the blank. Thermoplastic materials are not suitable for such a layer, since they would be affected by the heat energy of the heated press punches. We have found, however, that certain synthetic or silicon-based materials, when condensed in the form of a layer on the insulating plates, will prevent the aforedescribed adherence. These synthetic or silicon-based materials can be brought into a very solid and rigid state in which the layer also becomes heat-resistant. These layers of silicon-based or synthetic material give the working surfaces of the insulating plates the required character for a smooth operation of the prepressing process in the heated press.

The blank is first preformed on a heat-insulated support plate which is inserted into a heated press where the blank is prepressed, which causes the blank to attain a certain cohesiveness. After the prepressing step has been completed the press is reopened and the upper and lower insulated plates are withdrawn from the press, while the blank remains between the heated press punches. Subsequently thereto, the prepressed blank is further compressed in a known manner under the action of pressure and heat while the binding material hardens.

The subject matter of this invention may be incorporated in a single or multiple-story heated press. The heat transfer is at all times prevented by an upper and a lower heat-insulating plate. It is, however, at all times required to remove the insulating plates after the prepressing has been completed. This procedure can be accomplished in two different ways:

(a) The upper insulating plate, i.e. cover plate, is suspended above the blank and the pair of insulating plates together with the blank are then driven jointly between the heated press punches. After the prepressing step, the upper and lower insulating plates are driven by suitable transport means out of the heated press. The latter means may be embodied as a hinged lever. A suitable lifting and lowering mechanism is provided for the upper insulating plate, which first lowers the upper insulating plate onto the blank, and after the pair of insulating plates has been removed from the heated press, returns the upper plate thereof to its rest position where it remains until the operating cycle for the next blank is started. The pair of insulating plates are cleaned by suitable means as, for example, brush means, as they are being removed from the heated press;

(b) In a particularly advantageous arrangement of the machine of this invention the upper insulating plate is mounted on separate guide rails that extend over the level of the blank in the press feeding mechanism. The insulating plates are cooled during the waiting period between operating cycles by suitable cooling means, i.e. fan means. During the feeding operation the blank, which is supported on the lower insulating plate, is transported jointly with the upper insulating plate between the heated punches of the press, whereby the latter plate is moved on transverse guide rails between the heated punches. This arrangement is characterized in that the guide rails for the upper insulating plate are located outside of the physical limits of the reciprocating press punches and that both the upper and lower insulating plates are driven by the same or separate transport mechanisms which are, however, provided with separate coupling means for the upper and lower insulating plates so that the upper plate may remain between the press punches while the lower plate is removed from therebetween. Furthermore, cleaning means are incorporated in the heated press.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description when read in connection with the accompanying drawings in which:

FIG. 1 illustrates schematically the press machine of this invention before the feeding of the blank between the punches;

FIG. 2 illustrates schematically the prepressing step of the blank situated between the two protective heat insulating plates which are illustrated in FIG. 1;

FIG. 3 illustrates schematically the press machine of this invention after the removal of the upper and lower insulating plates;

FIG. 4 is a plan schematic view of the cleaning means illustrated in FIG. 3.

Referring now specifically to the drawing, in which the same reference characters are applied to similar structural components, it should be noted that the first process step comprises conveying the chips or shavings by sieving or spreading means into an insulating plate 6 until the uncompacted mass 7 has reached the desired height. Plate 6, together with another insulating plate 5, are then 4 moved, in a manner to be described below, between the heated punches 2 and 3 of the press machine 1. The press machine 1 is then closed and considerable pressure is applied to the blank 7 via the highly preheated punches 2 and 3 until the blank 7 is sufliciently compacted.

This prepressing step takes place quite rapidly and terminates when the punches 2, 3 are moved apart to the original open position; the lower insulating plate 6 which acts also as a transport and protective plate and the upper insulating plate 5 are then operatively removed from between the punches 2, 3 of the press (FIG. 3). Simultaneously therewith, the prepressed blank '7 remains in position between the punches 2, 3. In the final compaction step the preheated punches 2, 3 of the press are again closed and, during this step, transfer heat to the blank 7. This transfer of heat causes a curing and hardening of the binding and cementing material within the blank 7 and together with the applied pressure causes a further compacting of the blank 7. Thereafter the punches 2, 3 can again be moved apart and the finished blank 7 is then operatively removed. Due to the action of insulating plates 5, 6, the premature curing and hardening of the cementing and binding materials in the blank 7 is prevented. Such premature hardening, if not prevented, would make the prepressing process difficult or impossible. The transfer of heat from preheated press to the blank 7 is prevented or restricted by the insulating plates 5 and 6, the latter also functions as a conveying means. Since the prepressing process takes place quite rapidly, only a relatively small amount of heat is transferred from the preheated punches 2 and 3 of the device and, therefore, the insulating plates 5, 6 can be made of a material that has only relatively moderate heat insulating properties.

It should be noted that in the process of the instant invention, it is, advantageously, not necessary to unduly heat the transport plates 5, 6 by the press. Consequently, the wear normally caused by heat deformations can be eliminated. Furthermore, the device and process of our invention eliminates the necessity for a special separate prepressing installation, because both the prepressing step for initial compaction as well as the final pressing step for curing and hardening the cementing and binding materials takes place in one and the same press. In this manner, considerable savings in maintenance, installation and operating costs are accomplished.

The press machine 1 comprises the two press punches 2 and 3. The guide means for the insulating plate 5 is embodied as a pair of upper guide rails 4 which are always secured to the underside of the press punch 2 but lie outside of the physical limits of the stroke of the press punches 2 and 3. When the press machine 1 is closed during the prepressing step, the :blank 7, resting on insulating plate 6, is lifted by the press punch 3 and bears against insulating plate 5 so as to lift it off the pair of upper guide rails 4 and urges it against press punch 2, thereby the insulating plates preventing the transfer of heat into the blank 7. Thereafter, when the machine press 1 is again opened, insulating plate 5 automatically returns onto the pair of upper guide rails 4 along which plate 5 can be removed from between the press punches 2 and 3. The reciprocating movement of the plate 5 between the punches 2 and 3 and away from them can be done jointly with the plate 6 by means of, for example, a swingable arm arrangement (not illustrated). In such a press, the upper insulating plate 5 lies on the pair of upper guide rails 4 over the insulating plate 6 until the lower plate 6 is grasped by an auxiliary transport mechanism (not illustrated) and is separately removed from the shelf or shelves 8a onto the feeding arrangement 8 in order to receive a new untreated blank 7.

The construction and arrangement of the press machine of this invention is such that by means of separate coupling elements 5a, 6a for the upper protective insulating plate 5 and the lower transport insulating plate 6, only plate 6 is seized by feed arrangement 8 and moved to a feed station (not shown), where plate 6 receives a new blank 7 and then returns to feed the new blank into the press. After the prepressing of the blank 7 has been completed, the latter is removed from the insulating plate 6 and the latter, together with the insulating plate 5, is returned to the feed arrangement 8 for receiving a new uncompressed blank 7 and thereafter the aforedescribed operative cycle is restarted by again transporting the upper and lower plates and 6 together with the blank 7 between the press punches 2 and 3.

During the prepressing of the blank 7 and the subsequent withdrawal of the pair of insulating plates 5 and 6, there sometimes occurs damage to the blank 7 due to its lack of particle cohesiveness when it is slid off the plate 6. The chips of the damaged blank 7 must then be removed. The machine press of this invention is provided with a slide mechanism 9 which selectively moves into the press and removes the damaged blank 7 therefrom. The damaged blank 7, which has been slid off the press, is then received on a conveyor belt, worm gear or suction mechanism (not illustrated) which transports the chips of the destroyed blank back to the sieving and spreading means (not illustrated) for redistribution onto the plate 6.

The aforedescribed slide mechanism 9 comprises the slide surface 10 which extends over the entire width of the plate 6. The slide mechanism 9 may advantageously be provided Wit-h suction means having suction openings 11 along a part or the entire length of the surface It The slide mechanism 9 may also be provided with a pair of angularly shaped projecting slide members 10a which are mounted at an angle with respect to the slide surface 10. The members 10a prevent the falling of any chips onto the guide rails 4 of a lower stage of a multiple press (if the subject matter of this invention is embodied in such a multiple press) during the blank 7 sliding off the plate 6. The slide members 10a can advantageously be provided with auxiliary suction ducts which serve to remove the chips situated at the side of the plate 6 and on the guide rails 4. During the return stroke of the slide mechanism 9 there occurs an additional cleaning action by the aforementioned suction means.

While in accordance with section of the United States Code only best known embodiments of our invention have been illustrated and described in detail, it is to be particularly understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

Having disclosed and described our invention, we claim the following:

1. A process for manufacturing a composition plate out of a blank comprising a conglomerate of shavings and a binding material that hardens with the application of heat, comprising the steps of prepressing said blank in an essentially adiabatic manner in a preheated press by interposing between said preheated press and said blank heat insulating means prior to the prepressing thereof, operatively removing said heat insulating means from said preheated press, and pressing said blank to an essentially final shape by means of said preheated press and simultaneously therewith transferring heat to said blank from said press; and thereafter removing the formed composition plate from said press.

2. The process as set forth in claim 1 wherein said heat insulating means comprises a pair of plates made out of heat insulating material, and said preheated press comprises an upper and lower preheated punch, said pair of plates being interposed between said blank and said upper and lower punches prior to said prepressing step.

References Cited UNITED STATES PATENTS 3,268,642 2/1966 Hutter 264-12O ROBERT F. WHITE, Primary Examiner.

I. R. HALL, Assistant Examiner.

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