US2952059A - Apparatus for pressing plastic masses, particularly ceramic masses - Google Patents

Description

Sept. 13, 1960 cREMER ETAL 2,952,059

APPARATUS F OR PRESSING PLASTIC MASSES. PARTICULARLY CERAMIC MASSES Filed April 15, 1955 2 Sheets-Sheet 1 l wvewroaa I Gait med creme.

A ud WIJ BP/(ow 14? rd fi'rers Sept. 13, 1960 G. CREMER ET AL APPARATUS FOR PRESSING PLASTIC MASSES. PARTICULARLY CERAMIC MASSES Filed April 13, 1955 910% Lac! WI Azfred fiv 2 Sheets-Sheet 2 .l/VVE/VTURS -He.d Creme YEW United States PatentQ P APPARATUS FOR PRESSING PLASTIC MASSES, PARTICULARLY CERAMIC MASSES Gottfried Cremer, 6 'Steyrerweg, Koln-Junkersdorf, Germany; Ludwig Biilkow, 26 Meistersingerweg, Stuttgart- Degerloch, Germany; and Alfred Evers, 17 Silcherstrasse, Stuttgart-Vaihingen, Germany Filed Apr. 13, 1955, Ser. No. 501,112

'4 Claims. (CI. 25-82) This invention relates to an apparatus for pressing plastic masses and particularly ceramic masses between relatively movable press dies.

Generally speaking, plastic masses, and particularly ceramic masses, are pressed by pressing a suitably prepared cake into its final form between press dies, both of which are movable or one of which is movable and the other fixed. v

This operation is carried out mechanically, hydraulically, pneumatically, magnetically or in like fashion, if desired with the superimposition of vibrations or with the use of heat, electric charges or electric currents. In the methods of pressing plastic, and particularly ceramic masses known heretofore the press dies are arranged to be parallel to one another and to maintain this parallelism during the pressing operation. In numerous cases considerable effort is made carefully to maintain this parallelism of the press dies during the pressing operation. However, 'in a pressing operation of this character there arises the difficulty of eliminating the air imprisoned in the prepared press cake, particularly the air bubbles or air-filled spaces formed during the pressing operation. Without the elimination of these hollow spaces or air bubbles the production of a pressed article of a satisfactory nature is practically impossible.

It has accordingly been attempted to remove in various ways the air from the mass during the pressing operation. One known proposal consists in first moving the press dies towards each other and then once or several times first away from and then towards one another, in order in this manner to permit escape of air upon each pressing movement. In the invention a completely new procedure is adopted and a departure is made from the hitherto customary practice of arranging the press dies parallel to one another and of maintaining this parallelism of the dies during the pressing operation.

The apparatus according to the invention functions to carry out the pressing operation with such a relative movement between the upper and lower press dies that the relative speed of one end of the dies differs from that of the other end of the dies. For example, the pressing operation may take place by a surface rolling action of the top die over the lower die which receives the material to be pressed. It is also possible in accordance with the invention to superimpose in known manner a vibra- 'tory movement on the novel relative movement of the press dies. It is also possible to perform the pressing operation under the influence of heat which may be elfected by induction currents.

Typically the apparatus of the invention consists, for example, in the provision of the press dies in the form 2,952,059 Patented Se t. 13, 1960 ICC of a pair of tongs, so that they can be moved towards one another along an arc.

The fundamental idea according to the invention may be applied with particular advantage to rotary presses for the production of ceramic articles or the like.

It has already been proposed in the case of rotary presses for roofing tiles to mechanize to a large extent or even to render completely automatic the work of these presses. However, in carrying this into efiect it has been necessary in the known presses to accept as inevitable an increase in the diameter of the turret and accordingly an increase in the number of moulds on the turret, i.e. to increase the number of moulds from five to from nine to eleven. A further improvement in the mechanization or conversion to automatically of these rotary presses was envisaged by the change over from a horizontal turret to a rotary table having horizontal or tiltable moulds or to rotary table presses of truncated form.

However, in the latter case it is necessary to dispense with the main advantage of a turret, viz., the fact that the article being pressed moves automatically upon rotation of the turret into a position for delivery for further treatment and particularly for removal of the finished article without the moulds collapsing and without the necessity for auxiliary tools. 1 A further disadvantage resulting from an increase in the diameter of the turret for the purpose of obtaining automatic operation consists in the fact that, owing to the construction of the supporting structure, access to the sides of the turret and accordingly to the individual moulds, is rendered extremely difficult. If in such a construction automatic delivery of the clay cake, automatic removal of the burr, automatic smoothing, auto matic removal of the finished article, and so forth, were contemplated, access to the moulds and accordingly the possibility of cleaning them and maintaining them under observation would be completely prevented.

These disadvantages may be avoided by use of the principles of the invention as applied to rotary presses, there being possible not only a complete mechanization of the pressing operation but also adequate elimination of the hollow spaces or air bubbles in the article being pressed. 3

In the rotary press according to the invention the turret is mounted in cantilever fashion, making use of the principle of diiferent relative speeds of the two ends of the top and bottom dies, so that despite the lever mechanism, etc., necessary to mechanize the pressing operation the turret is well accessible from the side. All operation on the rotary press according to the invention can be readily observed and controlled. Replacement of the dies may be performed from the side much simpler and quicker than in the case of rotary presses with turrets supported on both sides as known heretofore. i In the press according to the invention the principle of different relative speeds of the two ends of the top and bottom dies is preferably eifected by constructing the ram of the press as a pivoted element having a toggle-lever drive adapted to the pressure characteristic of clay materials. The toggle-lever drive consists of a pressure and tension lever system by which it is possible to locate the entire drive towards the rear behind the bearing for the spindle of the turret, so that additional space for the turret is obtained, and the drive is not effected from above as heretofore. A pivoted element for the ram of the press, which is mounted and driven in the manner described, also has the can be adjusted simply. For example, the toggle-lever mechanism may be driven, by means of a crank drive, al-. I

though any other mechanical drive or a pneumatic, hy-

, draulic or other drive is also possible- When employing advantage that. the extent of movement of the press die a crank drive it is possible, for example, by varyingthe length of the connecting rod, to exceed the dead centre position and accordingly to achievea double stroke, i.e.

a two fold pressing operation, with one revolution of the crank. It is a pressing operation of this nature which is admirably suited for. many ceramic substances, as it is eccentric, again assumes theposition necessary for initia- I tion of the first movement.

Should a further adjustability of the stroke be desired, for example for adaptation to the consistency of 1 the material being processed and to progressive wear on the dies of the press, this may advantageously be effected in accordance with the invention by adjustment of the tension bearing for the toggle lever in the pivoted element. In contradistinctionto known constructions .thisfadjustment may be effected extremely simply; for. example by j the adjustment of aneccentric, without it being neces sary to removeany partsfrom themachiueor touse at 'tachmentsor the like. a i i An additional advantage of the construction according to the invention is that thepivoted elementforming the ram of thepress enables a turningof the turret to be a avoided and complete relief'of the turret drive, for ex-. j

ample a Geneva mechanism, to be obtained during the action of the powerful forces occurring during the pressing operation. p

In the accompanying drawings: j

Figure 1 is a diagrammatical view illustrating the prin- K ciple of the invention; I V I Figure 2 is an elevational view of a rotary press i structed according to the invention, .aud

FigureS is an endview of the press asseen from'the left ofFigure 2. A

According to Figure 1 the two press dies 1, 2 are mounted on arms 3, 4 respectively of atongs-like mem her, for example by means of screwsS, 6. The arms-3 and 4 are pivotally mounted on a shaft 7' and may be moved towards one another.

In the pressing operation the inner end 8 of the upper press die 2 first entersfinto contact with the material lo cated on the lower press die 1, so thatithe fpressingoperation commences at' this point and 'the'n progresses to ployed in similar fashion 'usinglumpy or granular s'ub stances; also-a dry pressing operation may be utilised in place of the pressing of plastic substances as described.

In the rotary press illustrated in Figures 2 and 3 the turret lluis mounted on bearings 13 whichlare indicated diagrammatically and which in turn are mounted on, a journal 12. This journal 12 is supported in the casing 14- of the rotary press at the points 16 and 17 constituting cantilever-like supporting or bearing surfaces. The drive of the turret 11 is eflected by means of the shaft 18 through the medium of the Geneva mechanism 19 and the driving wheel 20. On a pivoted member 21 is mounted and the lower dies 23 are provided. on the turret. As can be seen from Figure 2,. the upper die 22 may be readily removed towards the left, no obstruction being encountered by reason of 1 bearing structures or the like.

The member 21 pivots about the pivot 24 and is driven by a toggle-lever system 25 which comprises the toggle" levers 26, 27. The toggle lever 26is a tension lever and. the lever. 27 is a pressurelever. The bearing 28 in the casing 14 may begadjusted eccentirically. The tension bearing '29in1the pivoted member 21 isalso eccentrically adjustable, so that adjustment of the toggle-lever mechanism is possible both by Way of the eccentric mounting ofthe bearing 28 as well as the eccentric mounting of the tension bearing 29. The connecting rod30 is secured to the crank 31 and is adjustable in its length, so that if necessary the toggle-lever system 25 may be moved beyond its dead. centre position indicated at 32, the pivoted memher. "21.v andwwith it the upper die 22 being somewhat lifted. 1

i For the member is furnished with a guide bolt 33 engaging in slideways 34 on the frame 14 of the machine. Upon furtherdownwardmovemcnt the. projection 35 on they .guideboltengages in slideways in the turret. 'In this 3 way there. is established during the pressing out opera the other end 9 of the upper die until finally the desiredr end position is reached, in which the two dies are located practicallyparallel to one another. In this} mannerthe' mass being pressed undergoesa' general flowing move;

ment In the direction from the first towards the subse quently contacting end; This: general direction of flow may naturally have superimposed thereon local currents.

tion a rigid connection between the turret 11, the casing 14 and thepivotcd member 21 against forcesoccurring vertically to the plane of Figure 2. I i

i We claim:

a LA rotary'press for plastiemasses comprising a frame,

a turret having a plurality of dies, at cantilever-like support I in one end of theframe for one end of said turret, an arm pivotally mounted on said frame with the pivot remote from said turret carrying frame end, a die carried by said arm for recurrent cooperation with said turret dies respec- I tively, means comprising a toggle lever mechanism including lever means" pivotally interconnected betweensaid 7 frame and said arm for imparting rocking movementto I said. arm, whereby pressureis applied to a plastic mass first at oneend of the respective dies and then progressing along the mass to the other'ejnds of the dies, means I, to impart step-by-stepturning movement tosaidturret',

guide means on said frame adjacent saidturret, and means on saidarnt cooperating with said guide means for milidependent on the particular form of the article being A pressed. It has been found that when carrying out operations with a pressthus constructed the air imprisoned in the material is expelled practically in'its' entirety.

If desired, the pressing operation according to the into show the principle of the invention. i

' vention may also be 'carricd outwith a preliminary or subsequent pressing of thematerial or with repeated pressing. The embodiment illustrated ismerely intended For the sake ofsimplicity the drawings illustrate as an example apressing operation making use of prepared press cakes. The improved method may also be emrating against lateral displacement between said turret and pivoted arm during the pressing operation.

2. A rotary press'as claimed in claim 1 in which said last mentioned means comprises a guide bolt depending from :said pivoted arm, and said'guide means comprises a 'rigidguide on said frame into which saidbolt slides.

3." Arotary press as claimed in claim 2 comprising a projection on said guide bolt, and, slidewayson said Y turret into which, said projection extends thereby to'establish a; rigid connection between said turret, frame, and

pivotedarm against vertical forces. 1

'4. Arotary press as claimed in claim 1 including hear ing means for said toggle-lever mechanism, and eccentric the upper die 22 purposeiof relieving the Geneva mechanism 19=for the turret'there is provided in accordance withan additionalfeature of the'inventionadevice which-enters into operation upon the lowering of the pivoted member 21 and takes up the considerable lateral forces which may occur during thepressing out by the die. The pivoted 5 means for adjusting at least one of said bean'ngs there- 1,654,198 Whitlock Dec. 27, 1927 by to regulate the stroke of said toggle mechanism. 1,673,108 Ellery June 12, 1928 2,433,013 Ziegler Dec. 23, 1947 References Cited in the file of this patent 2,496,609 Antwerpen Feb. 7, 1950 UNITED STATES PATENTS 5 FOREIGN PATENTS 776,577 Welling Dec. 6, 1904 415,408 France Apr. 30, 1910 984,933 Klay Feb. 21, 1911 159,648 Germany Apr. 7, 1905

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