Method and device for cutting and shaping a sheet or slab of paste based in particular on clays for making ceramic objects

A method of cutting and shaping a sheet or slab of soft, tearable and scalable paste, constituted for example by agglomerated solid or plastic particles, based in particular on clays, for the manufacture of ceramic objects or pieces, said objects being cut out of a slab portion constituting a blank by means of suitably contoured cutters which are caused to penetrate into the said paste laid on a bearing support having the desired shape, after which the trimmings are removed. In order to allow the objects cut out of the said blank to be recovered, the said cutting is performed on a supple film or hand laid on the said support, for example a plastic film or sheet, which is apt to conform in shape to the objects cut out, which does not adhere to the said objects and which is not cut by the said cutters, the objects thus cut out being thereafter separated from the said supple band.

The present invention relates essentially to a method for cutting and 
shaping a sheet or slab of soft, tearable and scalable paste, constituted 
for example by agglomerated solid or plastic particles, based in 
particular on clays, for making ceramic objects, the said objects being 
cut out of a blank constituted by a portion of the said slab by means of 
suitably contoured cutters which are caused to penetrate into the said 
paste laid on a bearing support having the desired shape, the resulting 
trimmings being thereafter removed. 
By such a method, objects having the desired dimensions and shape can be 
cut out of a slab of larger dimensions, the said objects being thereafter 
fired or baked into glazed tiles, dishes and generally all kinds of 
finished ceramic products or ware. 
One of the essential difficulties encountered is that, the paste being 
friable, it is relatively difficult to be cut and therefore still more 
difficult to be shaped without spoiling the object. This leads to very 
delicate handling and quite extensive waste which considerably increase 
manufacturing costs and adversely affect the quality of the finished 
products. One of the purposes of the invention is to overcome this 
difficulty involved in the cutting and shaping processes. 
To this end, the invention provides a method in which, in order to allow 
the objects cut out of the slab blank to be readily recovered, the said 
cutting is performed on a sheet-like film or a supple band, for example a 
plastic film or sheet, laid on the bearing support, the said supple band 
being so selected as to conform in shape to the objects cut out but not to 
adhere to the pasty material and not to be cut by the cutters, thus 
allowing the objects cut out to be separated from the said band without 
being spoiled. 
According to another feature of the method of the invention, the objects 
cut out being substantially flat and having to be thereafter processed in 
a kiln on firing or baking plates, the said objects are transferred onto 
the said firing plates by being conveyed thereto on the said supple band. 
Owing to the method of the invention and as will appear more clearly from 
the description that will follow, utmost facilitation of the handling is 
obtained and the risks of deterioration of the objects cut out are 
considerably reduced. 
The method according to the invention can be readily automated or 
semi-automated. To this end the invention provides a device for carrying 
out the above-mentioned method, characterized in particular in that it 
comprises : a movable frame or drawer provided with the said supple band 
and displaceable on a bearing surface, the said bearing surface including 
a blank pressing counter-plate on which the cutting of the blanks takes 
place and a firing or baking plate on which the objects cut out are 
deposited in order to be subsequently fired in a kiln, the said frame 
being movable between two positions, in one of which the said band is 
located substantially above the blank pressing counter-plate whereas in 
the other position the said band is located substantially above the firing 
plate, the said device furthermore including a retractable or move-aside 
stop member above the said bearing surface between the said pressing 
counter-plate and the said firing plate.

Reference is first made to FIGS. 1 to 8. 
According to the form of embodiment illustrated in these Figures, a device 
for cutting a slab constituted for example by agglomerated clay particles 
for the manufacture of ceramic objects comprises essentially a carriage 1 
movable along guide rails 2 through the medium of rollers 3 between end 
stops 4, 5 provided on the rails 2. The carriage has an upper supporting 
or bearing surface 6 in which are provided three cavities 7, 8 and 9. The 
cavity 7 accommodates a firing or baking plate 10. The cavity 8 receives a 
pressing counter-plate 11 which, in the example illustrated and as seen 
more clearly in FIG. 8, is constituted by an upper plywood layer 12 and 
three layers 13, 14 and 15 of, for example, foam rubber ensuring good 
pressure absorption during the cutting of the blanks by the punch-out tool 
16 (FIG. 2) as will be described later. 
The cavity 9 accommodates three rolls or bars 17, 18, 19. The two upper 
rolls 17, 19 are arranged quite close to one another and so that their 
upper generatrix is flush with the plane of the bearing surface 6 of 
carriage 1. The roll 18, on the contrary, is entirely located below that 
plane. 
On the carriage 1 is placed a movable frame or drawer member 20, the shape 
of which appears more clearly in FIG. 7. It is provided with a sheet or 
film defining a supple working band or strip 31 which passes over the 
rolls 17, 19 and under the roll 18 acting as deflecting means as will 
appear later. The said supple working band is advantageously constituted 
by a sufficiently supple and strong fabric or like material, e.g. of the 
"oil cloth" type. 
The movable frame is provided with travel limiting stops 21, 22, 
respectively, which, in the end positions of the movable frame, abut 
against corresponding opposite stops 23, 24 provided on the carriage 1. 
Furthermore a retractable or move-aside stop plate 25, the function of 
which will appear later, is provided above the bearing surface 6 of the 
carriage between the pressing counter-plate 11 and the firing plate 10. 
The operation and use of the device will now be described with reference to 
FIGS. 1 to 8. 
Referring to FIG. 1 and, in order to facilitate the description, 
considering the "rear" side to be the left-hand side designated by AR in 
FIG. 1 and the "front" side to be the right-hand side designated by AV in 
the same Figure, the carriage 1 is shown to be in its rear position in 
which the rollers 3 abut against the rear stops 4 of the rails 2. 
The movable frame 20, on the contrary, is pushed forward to its front 
position in which the stops 22 abut against the stops 24 of the carriage 
1. 
A free firing or baking plate 10 is placed in the cavity 7 of the carriage. 
A blank 26 constituted for example by a portion of a slab of agglomerated 
clay particles is then placed on the working band 31 of the movable frame 
20 and substantially above the pressing counter-plate 11. 
The carriage is thereafter pushed forward in the direction of arrow 27 so 
as to move the pressing counter-plate 11 beyond the line 28 which can be 
materialized by a safety screen or curtain (not shown) of the cutting 
press. 
Reference is now made to FIG. 2 in which the carriage 1 is shown in its 
advanced position with its rollers 3 abutting against the front stops 5 of 
rails 2. At 16 is diagrammatized the press punch-out tool moved down into 
the blank 26, thus cutting pieces 29 out of the latter and resulting in 
trimmings 30 around the said pieces. 
Thereafter the punch-out tool 16 of the press moves upwards. 
As illustrated in FIG. 3 and indicated by arrow 32, the carriage 1 moves 
back until its rollers abut against the rear stop 4 of rails 2. 
Then the trimmings 30 are eliminated, e.g. withdrawn manually. In that 
position, the movable frame 20 is still in its advanced position (not 
shown in FIG. 3). 
The movable frame 20 is then moved back as indicated by arrow 33 until its 
rear stops 21 abut against the stops 23 of the carriage. During this 
backward movement the objects 29 cut out and previously freed from the 
trimmings are transferred from the pressing counter-plate 11 to a location 
above the firing plate 10 by the supple working band 31 of the movable 
frame 20. During this transfer movement and owing to the deflecting means 
constituted by the three rolls 17, 18, 19, the working band 31 passes 
below the plane of the carriage bearing surface 6, on the narrow gap 34 
comprised between the rolls 17, 19. During the transfer, this gap sweeps 
the objects 29 over their whole length, thus ensuring a first separation 
of the lower face of the pieces 29 from the upper face of the working band 
31. This separation takes place progressively and linearly without 
spoiling the pieces. 
In the rear position of carriage 1 illustrated in FIG. 3, the stop plate 25 
is lowered as indicated by arrow 35. 
From that moment and as illustrated in FIG. 4, the movable frame 20 may be 
moved forward as illustrated by arrow 36 until the stops 22 of the frame 
20 abut against the stops 24 of carriage 1. During this displacement of 
the frame 20, the cut-out pieces 29 retained against the stop plate 25 
slide on the surface of the working band 31 and thus remain on the baking 
plate 10. 
As illustrated in FIG. 5 by arrows 37, it is then sufficient to withdraw 
the firing plate 10 supporting the objects 29 for further treatment of the 
ceramic products in a kiln. 
In the form of embodiment just described, the stop plate 25 moves jointly 
with the carriage 1 and can be raised or lowered vertically to fulfill its 
function as a stop as explained above without interfering with the 
operation of the carriage and the movable frame. Other types of 
retractable or move-aside means may of course be provided; for example the 
stop may be moved aside transversely by means of an actuating cylinder, or 
a system with a lateral hinge may be provided to fulfill the same 
function. 
Reference is now made to FIGS. 9 to 11 illustrating a method and a device 
which, according to the invention, allows standardized production of 
objects such as for example ceramic tiles and rounded-off edges. 
To this end, and as illustrated in FIG. 9, a sheet-like supple working band 
such as, for example, the band 31 described with reference to the 
foregoing Figures, is placed on the pressing counter-plate 11. On this 
band 31 is laid the blank 26 constituted by a portion of a slab of, for 
example, agglomerated clay particles. By means of a punch-out tool such as 
for example the press tool 16 shown in FIG. 1, pieces having the desired 
dimensions are cut out of the blank 26. 
In order to provide the objects thus cut out with rounded-off edges, a 
supple sheet-like film 38 such as for example a thin polyethylene film is 
arranged, before the lowering of the tool, between the blank 26 and the 
punch-out tool 16. 
The cutting edge 39 of tool 16 is sufficiently sharp to cut out the objects 
29 (FIG. 10) during the lowering of the tool 16 onto the pressing 
counter-plate 11 and sufficiently blunt to avoid cutting the thin film 38. 
Besides, the pressing counter-plate 11 is so structured as to act as a 
buffer favouring the correct cutting out of the pieces 29 and the 
non-cutting of the film 38. 
During the downward motion of the tool 16 into the blank 26, the film 38 
(FIG. 10), owing to its inherent elasticity or flexibility, is driven 
along by the cutting edge 39 of the tool, thus exerting a pressure on the 
edges of the objects 29 and rounding off their angles as clearly shown in 
FIGS. 10 and 11. Since the film 38 is not cut by the tool edge 39, it is 
sufficient (FIG. 11), after having raised the tool 16, to remove the film 
38 and eliminate the trimmings 30 to obtain the objects 29 with 
rounded-off edges. 
If, unlike the form of embodiment of FIGS. 9 to 11, it is desired to obtain 
objects cut out with sharp angles, use can advantageously be made, as 
illustrated in FIG. 12, of a box-shaped punch-out tool 40 with a lower 
cutting edge 41 for cutting the blank 26 laid on the supporting band 31, 
itself supported by the pressing counter-plate 11. Within the box portion 
of the tool 40 is provided a pad 42, for example of felt impregnated with 
an appropriate lubricant, the said pad being applied against the inner 
wall of the tool 40 so as to continuously lubricate the internal wall of 
the cutting portion 41 to prevent the pasty material of the blank 26 from 
sticking within the tool 40. Furthermore, the lubricant-impregnated pad 42 
may advantageously be placed between two layers of foam rubber or another 
compressible elastic material, the lower surface of the lower layer 44 
being substantially flush with the plane of the cutting edge in the 
position of rest of the punch-out tool 40. Thus, when the punch-out tool 
is lowered into the blank 26 so as to cut the same, the layers 43, 42, 44 
are compressed, allowing the piece being cut to penetrate into the 
punch-out tool, the internal wall of which is lubricated. During the 
following upward movement of the tool 40, the object cut out is easily 
ejected from the tool owing to the lubrication of the wall of the box 40 
and to the elasticity of the layers 43, 44. This ensures a clear-cut edge 
of the objects out of the blank 26. 
Advantageously, an elastic cushion, for example of foam rubber somewhat 
similar to the cushioning means constituted by the elastic layers 43, 44 
of the tool 40 of FIG. 12 may be placed in the punch-out tool 16 of FIGS. 
2 and 9 to 11, so as, in particular, to facilitate the extraction of the 
cut-out piece from the tool, the said elastic cushion being substantially 
on a level with the lower or cutting edge of the tool in its position of 
rest. 
Referring now to the form of embodiment of FIGS. 13 to 15, there is 
illustrated a method of cutting and forming shaped, non-flat objects from 
a plane slab according to the invention. 
The device allowing such a cutting comprises essentially a form 
constituting a punch 45 and a counter-form constituting a mating die 46. 
The form 45 includes a supporting body 47 on which is mounted a cutter 48, 
the body 47 being provided with a suitable filling material 49, for 
example of plaster, plastics or light alloy. 
The counter-form 46 is provided with a hollow 50 and vent passages 51 
opening onto the surface 52 of the counter-form for reasons which will 
appear hereafter. 
According to the method of the invention, a supple compressible support 
sheet 53, for example of rubber, is placed on the upper face of the 
counter-form 46. 
On this layer of foam rubber 53 is placed a sheet-like supple band or film 
54, for example of polyethylene. Over the latter is placed a blank 55 
constituted by a portion of a slab of, for example, agglomerated clay 
particles. Over the blank 55 is placed a second thin supple film 56, for 
example of polyethylene. 
As illustrated in FIG. 14, the form 45 is thereafter applied on the 
counter-form 46 until the counter-pressure of the pressing counterbalance 
the pressure of application of the press. In this position, as illustrated 
clearly in FIG. 14, there is left between the form and the counter-form a 
sufficient space to accommodate the supple compressible support 53 in the 
compressed state, as well as the blank 55 confined between the two films 
54, 56, with the cutter 48 of the form driven into the pasty material of 
the blank 55, thus deforming the protective films 54, 56 without cutting 
them. 
The mutual counter-balancing of the pressing pressure and the forming 
counter-pressure automatically ensures an adjustment of the press travel 
irrespective of the thickness of the blank 55. 
Thereafter, it is sufficient to separate the form 45 from the counter-form 
46. Under such conditions, and as illustrated in FIG. 14, the supple 
support band 53, owing to its elasticity and to the vent passages 51, 
straightens out on the counter-form 46, thus freeing on itself a cut-out 
and shaped non-planar object 58 with trimmings 59, the said object being 
protected between the two films 54, 56. The piece 58, for example a 
dish-shaped object, is then subjected to baking after the protective films 
54, 56 are removed. 
It is thus apparent that according to the method of the invention a slab of 
soft paste (26 or 55) is placed on a flexible film (31 or 54) while the 
latter rests on an elastic support (formed by the unit 11 or sheet 53), 
and then this slab is cut through to form a slab piece (29 or 58) of a 
given configuration as well as slab trimmings (30 or 59), the cutting 
action applied during cutting through the slab being such that the 
flexible film is not cut while the elastic support absorbs the cutting 
forces. After the slab has thus been cut through, the trimmings are 
removed and the slab piece is separated from the flexible film and then 
further treated. 
Of course, the invention is by no means limited to the forms of embodiment 
and of carrying out described which have been given by way of example 
only. The invention comprises all the technical equivalents to the means 
described as well as their combinations should the latter be carried out 
according to its gist and used within the scope of the following claims.