US 2512275 A
Description (OCR text may contain errors)
Patented June 20, 1950 OFFICE APPARATUS FOR FORMING coNcAvE SURFACED ARTICLES Elwin A. Hawk, East Rochester, Ohio Application October 7, 1948, Serial No. 53,274
The invention or discovery relates generally to apparatus for forming concave surfaced articles by pressing operations on charges of fiowable and formable material; and particularly to apparatus for pressing charges of ceramic material to form pieces of ceramic ware having concave surfaces, such as cups, saucers, bowls, dinner- .ware, and similar hollow articles. I
In forming ceramic ware from charges of ceramic material by pressing operations, prior apparatus for forming cups for example, have included the use of mating dies, one of which is a convex plunger, and the other of which is a concave receiver having a cavity in which the charge of ceramic material is placed. One of the dies, usually the concave receiver, is made of porous material such as paster of Paris, and the other die is made of metal.
When mating dies only are used to press form ceramic ware from charges of ceramic material, difiiculty is encountered in obtaining the proper flow of the charge between the dies during the pressing operation, and the formed piece of ceramic ware has a tendency to stick to the dies and tear when the dies are separated.
, Fabric has been tied to the convex plunger in an effort to remedy the difficulties inherent in the use of mating dies only in the press forming of ceramic ware, but it has been found that when the dies are separated after a forming operation, the fabric tied to the plunger does not release paratus for utilizing flexible fabric sheet material between one or both o-fthe dies and the charge in the press formingof concave surfaced articles from flowable and formable material in such manner.that thefiexible fabric sheet material may be reconditioned after each use.
The foregoing and other objects are attained by the co-ncave surfaced article forming apparatus, parts, combinations, and subcombinations which comprise the present invention or discovcry, and the nature of which is setforth in the from the formed piece of ceramic ware in the material of the charge after making several impressions, necessitating removal of the fabric cleaning or replacement.
The objects of the present invention or discovfor ery include the provision of improved apparatus for press forming concave surfaced articles such as ceramic ware from flowable'and formable material such as ceramic material in such a manner that the surface configurations and wall shapes of each formed piece of ceramic ware are not altered when the dies are separated.
Further objects of the present invention or discovery include the provision of improved apparatus for obtaining a different and more satisfactory flow of the charge material between the dies in the press forming of concave surfaced articles, than has been the case in the use of prior methods and apparatus.
Further objects of the present invention and discovery include the provision of improved apfollowing general statement, and preferred embodiments of which areset forth in the following description, and which are particularly and distinctly pointed'out and set forth in the appended claims forming parthereof. j v
The nature of theimproved apparatus of the present invention may be stated in general terms as including in apparatus for press forming ceramic ware and the like, mating dies. including a concave die .and a convex die, the convex die having a cavity with an outer opening, means for movingthe dies with respect to each other between spaced apart positions and positions in which the convex die is within the cavity of the concave die, a sheet of flexible material between the dies and freely movable with respect to the dies and sufficiently thin to assume the conformation .of the convex die without rupture, means for effecting movements of the sheet includin a stripping member at one side of the concave die arranged to contact the sheet at one locus and move the sheet out ofthe concave die cavity after a charge of ceramic material has been placed in the cavity beneath the sheet and has been formed by movement of the dies so that the sheet and the charge beneath the sheet have been pressed between the dies.
By way of example, embodiments of the improved apparatus for. forming ceramic ware of the present invention or discovery and of improved parts thereof are illustrated in the accompanying drawing forming part hereof, in which:
Figure 1 is anelevational view, diagrammatic in part, showing the improved apparatus with the dies and flexible sheet spaced apart permitting charging, and showing a charge of ceramic material in the cavity. of the concave die; and
Fig. 2, an enlarged view of portions of Fig. 1 after a pressing operation of the dies, separation of the dies, and with the stripping member ready to release theflexible sheet from a formed piece of ceramic ware.
Similar numerals refer to similar parts throughout the drawing.
The illustrated. embodiment of the improved is secured on the upper end ofthe ram HR The reciprocating fluid motor l may be double acting:
and its piston and connected ram l=4- may bereciprocated towards and away from the block l2 in a usual manner by the alternate'valve con! trolled admission and exhaust of working fluid.
such as compressed air or oil under pressure into and out of the chambers of the cylinder IS on opposite sides of the piston;
Mating dies in the apparatus H! includea lower concave die I! and an upper convex die 18. The concave die ll is seated in the die seat I3 on the block l2 and includes walls forming an upwardly opening cavity t9- havingadeep concave upper surface 20,, which as shown is a surface of revolution about the vertical axis indicated by the, dot-dash lin'e' 2l' which is also the longitudinal axis of the ram Id; The upper convex die V8 is secured to'and" depends from the lower end of the ram l4, and the convex die l8 has a convex outer surface 22 which is also a surface of revolution about the axis 2|. 7
As shown, the mating dies l1 and I8 are ceramic cup forming dies for forming a charge 23 of ceramic material placed at the bottom of the cavity it in the concave die H as shown in Fig. I into the concave surfaced ceramic cup 23--l as shown in Fig. 2.
The improved apparatus H] for forming concave surfaced articles furthermore includes a sheet of, flexible material 24 located between the mating dies l1 and IB. As shown, the sheet of flexible material 24 is an elongated strip.
At each side of the block l2:, there is mounted on the base ll an elevator indicated generally by 25 each of which as shown is a usual reciproeating fluid elevator including a cylinder 26 in the vertical bore '21 of which a piston 28 is reciprocatable in. a usual manner by the admission and exhaust of fluid such ,as compressed air or oil under pressure into and out of the cylinder chamber 29 below the piston 28. An upwardly extending. piston rod 30 has its lower end connected to each piston 28, and a reel bearing bracket 3! is secured and supported on the upper end of each piston .rod 30.
Each reel bearing bracket 31 has journaled thereon a reel 32' which is'connected with one end of the strip of flexible sheet material 24. Each reel 32 has Wound thereon end portions of the strip of flexible sheet material 24. One of the reels 32 may be'provided with usual ratchet means not shown permitting free unwinding of the strip of flexible sheet material 24 therefrom, and the other reel 32 may be simllarl'ymounted and in addition be arranged for winding up the strip of flexible material 24 thereon by usual means not shown.
At one side of theblock l2, flexible sheet material stripping means are operatively mounted, which as shown includes a reciprocating fluidelevator 33, generally similar to the elevators 25, and including a cylinder 34 in the vertical bore of which a fluid actuated piston is reciprocable,
and the lower end of a piston rod 35 is connected to the piston of the elevator 33. A roller mounting yoke 36 is secured and supported on the upper end of the piston rod 35, and a roller 3! is journaled in the yoke 36, the roller 31 having a transversely convex outer curved surface of revolution 38.
Ihe improved methods of the present invention or discovery include broadly the steps of separating mating dies, such as the concave die 1"." and the convex die l8, placing and supporting a: charge. of 'flowable and formable material in or on one of'the dies, such as a charge 23 of ceramic material in the bottom of the cavity is of the concave die If, covering the charge supporting die and; the charge with a piece of flexible sheet material, such as strip 24 which is freely movable with respect to the dies and which is adaptable to assume the conformation of the non-charge supporting die without rupture such as the convex die t8, pressing the charge and the covering pieceof' flexible sheet material between the mating dies and forming the charge into a concave surfaced article such as'the cup 23l, separating the dies, and removing the covered piece of'flexible sheet material from the formed articles by progressive stripping or peeling from a start- 7 ing point;
The improved method may be carried out by manually covering the charge and its supporting die with a piece of flexible sheet material and by manually removing the piece of flexible sheet material from the formed surface of the formed article by grasping the piece of flexible sheet material at one side and progressively peeling the piece of flexible sheet material from the covered formed surface ofthe formed article. Removal of the covered piece of flexible sheet material from the formed surface of the formed article may be otherwise described as the application of a concentratedforce to a restricted area of the piece of'sheet material in a direction serving to progressively peel the sheet from the formed article.
Preferably the piece of sheet material is mechanically handled in improved apparatus such as the apparatus [0. Referring to Fig. 1, the concave die IT is made of porous material such as plaster of Paris, and a separate die [7 is placed in the die seat l3 of the block [2 each time a charge of ceramic material 23 is to be formed, as is usual in the press-forming of ceramic articles. The elevators 25 are operated by" usual valve control means to raise their pistons 28 and piston rods 30 and the supported reels' 32' and strip of flexible sheet material 24 to the uppermost position shown in full lines in Fig. 1 providing plenty of room for placement of the concave die I1 and deposit of the charge of ceramic material 23 in the bottom of the cavity IQ of the concave die l1. After the charge of ceramic material 23 has been placed in the concave mold l! the elevators 25 are operated to lower the pistons 28 and piston rods 36) and the supported reels 32 to a position in which the strip of flexible sheet material 24 extending between the rolls rests on the top faces of the concave die I! and covers the outer opening of the cavity l9 and the charge of ceramic material 23 therein. The strip of flexible sheet material 24 is freely movable with respect. to the mating dies 11 and I8, and is adapted by its dimensional and physical characteristics to assume the conformation of the convex die 18 without rupture.
Accordingly, when the reciprocating fluid motor I5 is operated to lower'the piston rod l4 and theconvex die l8 under pressure,the strip :ofcovering flexible material; 24 is pushed into the. cavity I9 of the lower concave die ,l'l, as
the. conformed portion ofthe strip of flexible sheet material 24 presses against the charge of ceramic material 23 in the cavity l9 of the concave die I! by the pressure of the convex die l8 on the top surface of the strip of flexible sheet material 24, thereby pressing the convex die contacted portion of the strip of flexible sheet material 24 and the charge 23 of ceramic material between the mating dies I! and I8 and forming the charge 23 into the concaved surface piece of ceramic ware 23l, which is a cup as shown. During the press-forming operation, the charge flows freely between the surface of the cavity IQ of the concave die I! and the opposite surface of the pressed portion of the strip of flexible sheet material 24.
When the upper convex die I8 is raised and the dies are separated, as shown in Fig. 2, the conformed portion 24-l of the strip of flexible sheet material 24 remains in contact with the inner concave surface of the formed cup 23-| until removed therefrom by operation of the improved stripping means. The ends of the strip of flexible sheet material 24 are yieldingly wound on the reels 32, and the outer curved surface 38 of the roller 31 makes a point or restricted area contact at 40 with the under surface of the strip of flexible sheet material 24. The elevator 33 of the stripping means is then operated to elevate its piston and piston rod 35 and the supported roller 31, whereby the curved surface 38 of the upwardly moving roller 31 applies a concentrated force to a restricted area of the strip of flexible sheet material 24in an upward direction and serves to progressively peel the strip of flexible sheet material from the formed cup 23l, commencing at the left side as shown in Fig. 2.
After removal of the pressed portion of the strip of flexible sheet material 24 from the'concave surface of the formed ceramic cup 23--l by the progressive peeling action, there is found to be no distortion or tearing of the concave surface of the ceramic cup 23l, as is usual when mating dies alone are used for pressforming ceramic articles, or when flexible sheet material is tied or secured to the pressing die, such as the convex die or plunger l8.
After each forming of a piece of ceramic ware in the apparatus [0, the winding reel 32 is turned to move the last pressed portion of the strip of flexible material 24 away from its position over the top of the concave mold I! and to locate a fresh portion of the strip of flexible sheet material 24 over the top of the concave mold I'I. Each pressed or used portion of the strip of flexible material 24 may be reconditioned after each impression by drying, washing, brushing. or otherwise cleaning, or by treating with ceramic slip.
In the apparatus 10, as above stated, the concave die I1 is formed of porous material such as plaster of Paris, and the convex die I8 is made of metal, as is usual in dies for pressform- 6-. iin'g cups having deep concave surfaces or -cavlties.:':": i
' When forming dishes or plates thelower die is usually aconvex die made of porous material such as-plasterofParis, and the upper die is a concave plunger made of metal. The charge of ceramicmaterial is placed and supported on the lower convex die and covered by the piece of the fiexiblesheet material. The press-forming of the concave surfaced ceramic articles is I a preliminary operation-before jittering, in which the concave surfaces and edges are finish formed by the jittering tool.
In some instances a piece of the flexible sheet material may be placed under the charge as well as over the charge, and the charge may be pressed between the pieces of flexible sheet material.
The flexible sheet material may be flexible fabric woven of either metallic or non-metallic strands and having a fine mesh and thin gauge such as to adapt the flexible fabric to assume the conformation of the contacting die. Fexible nylon fabric has been found to be particularly suitable for use in carrying out the improved methods and in the improved apparatus of the present invention and discovery, and nylon fabric of from to 300 mesh woven from nylon strands of about 0.003 gauge has been found 4 suitable.
It has also been found that when the sheet of flexible material is made of latex, the latex is inherently adapted for progressive release from the formed article.
The embodiments of the improved apparatus and the method steps described herein are by way of example, and the scope of the present invention is not limited to the same or to the particular details thereof but is commensurate with any and all novel subject matter contained herein which may at any time properly under the patent laws be set forth in the claims hereof or originated herein, and the elements of any such claims are intended to include their reasonable equivalents.
1. In apparatus for the press forming of concave surfaced articles, mating dies including a concave die and a convex die, the convex die having a cavity with an outer opening, means for moving the dies with respect to each other between spaced apart positions and positions in which the convex die is within the cavity of the concave die, a strip of flexible sheet material between the dies, means yieldingly supporting the strip of flexible sheet material, and means for effecting movement of the strip of flexible sheet material with respect to the dies including a stripping member at one side of one of the dies and at one side of the strip of flexible sheet material and means for moving the stripping member to contact one side of the strip of flexible sheet material and move the strip of flexible sheet material away from one of the dies.
2. In apparatus for the press forming of concave surfaced articles, mating dies including a concave die and a convex die, the convex die having a cavity with an outer opening, means for moving the dies with respect to each other between spaced apart positions and positions in which the convex die is within the cavity of the concave die, a strip of flexible sheet material between the dies, means yieldingly supporting the strip of flexible sheet material, and means for effecting movement of the strip of flexible sheet material with xt spesi to the: dies including a stripping roller at one side of one of the diesand atv-one. side,- Qf the st p; f: flexib e sheet mat r al anvismeans -f; zv 1- mqvima-theystripping: roller to-convmet one side'of the} strip of flexible sheet. material; and; move the slirip qf flexible sheet material away from one of the dies.
- v ELWIN A. HAWK.
REFERENCES CITED Nmnb'er 10 Number 8 UNITED S'ITATI S- PA'IEN-I'S Name Date Mishl'er Aug. 26, 1879 Mitchell- Oct. 22, 1889 Weber, Jr June 18, 1901 Prosser Mar. 1'1, 1914 Cross May 8, 1934 FOREIGN PATENTS Country Date Great Britain 193.0