CLAIMS
1. Method, for producing porcelain objects with at least one through-hole, characterized in that it comprises the following steps: - preparation of a bottom half-mould (10) having a half-seat (11) with a form corresponding to that of the object to be obtained;
- provision of a blind hole (12) with a vertical axis in said half-Beat (11) of the bottom half-mould (10) ; - preparation of a top half-mould (20) having a half- seat (21) with a form corresponding to that of the object to be obtained;
- provision, in this top half-mould (20) , of a through- hole (22) coaxial with the blind hole (12) of the bottom half-mould (10) ; provision of a tubular member (31) open at the opposite ends and provided with upper holes (32a) and lower holes (32b) formed on the side surface at suitable distances from the respective opposite ends of the tube ;
~ provision of a cup (33) for supplying the liquid porcelain (P) to be cast and with a hole in its bottom surface, having an inner diameter corresponding to the outer diameter of the tube (31) ; - joining together of the two half-moulds (10, 20) in the vertical direction Z-Z;
- insertion of the tubular member (31) inside the two moulds, i.e. top half-mould (20) and bottom half-mould
(10) , via the respective through-hole (22) and blind hole (12) ;
- mounting of the cup (33) on the tube part ( 31) projecting from the top half-mould (20) ;
- casting of the liquid porcelain (P) inside the cup '
(33); - penetration of the liquid porcelain (P) inside the tube (31) through the upper radial holes (32a) ;
- flowing out of the porcelain (P) into the seat (Il , 21) through the lower radial holes (32b) ;
- expulsion of the air (A) from the mould through the upper opening in the tube (31) ;
- drying of the part (100) with hole (110) obtained;
- opening of the mould;
- extraction of the part.
2. Method according to Claim 1, characterized in that said bottom blind hole (12) and top through-hole (22) are coaxial with the centre of the part (100) to be formed ,
3. Method according to Claim 2 , characterized in that it envisages the further steps of:
- providing first transverse seats (15, 25) in the respective half-moulds (10, 20), arranged in positions such that the opposite ends emerge outside the half- moulds (10, 20) and inside the central hole (12, 22), respectively;
- inserting, in the seat (15, 25) , a pin (55) able to produce, during casting, the formation of a transverse hole (120) which passes through the part (100) from the side surface (100a) to the inside of the vertical through-hole (110) .
4. Method according to Claim 2, characterized in that said part is the case (100) of a watch.
5. Method according to Claim 4, characterized in that said vertical through-hole (100) is centred with respect to the said case (100) .
6. Method according to Claim 4, characterized in that said vertical through-hole (110) is a pre-hole able to be widened to the size of the watch mechanism to be housed inside it .
7. Method according to Claim 4, characterized in that said transverse through-hole is the seat for the spindle (130a) operating the hands of the watch.
8. Method according to Claim 4, characterized in that it envisages the further steps of :
- providing second transverse seats which pass through the respective half-moulds (10, 20) in the transverse direction (Y-Y) in a location corresponding to that of the strap holder cross-pieces (101) ; - inserting, in the seats (155) , a pin (55) able to produce, during casting, the formation of a transverse hole (120) which passes through said cross-pieces (101) ao aa to form a through-seat (101a) in them.
9. Method according to Claim 1, characterized in that said cup (33) for containing the porcelain (P) is integral with the tubular member (31) .
10. Mould for producing porcelain objects (100) with at least one through-hole (110) , characterised in that it comprises:
- a bottom half-mould (10) with a half-seat (11) having a form corresponding to that of the object to be obtained, said bottom half-mould (10) being provided with a blind hole (12) having a vertical axis in said bottom half-seat (11) ;
- a top half-mould (20) with a half-seat (21) having a form corresponding to that of the object to be obtained, said top half-mould having, formed therein, a through-hole (22) coaxial with the blind hole (12) of the bottom half-mould;
- a tubular member (31) open at the opposite ends and provided with upper and lower holes (32a) formed in the side surface at suitable distances from the respective
5 opposite ends of the tube (31) and able to be coaxially inserted inside said top through-hole (22) and bottom blind hole (12) so as to supply the liquid porcelain
(P) to the said half-seats (11, 21) .
10 11, Mould according to Claim 10, characterized in that the top part of the tubular member (31) has, associated with it, a cup (33) for containing the mixture (P) of liquid porcelain.
15 12. Mould according to Claim 11, characterized in that said cup (33) is integral with the tubular member (31) .
13. Mould according to Claim 12, characterized in that said upper radial holes (32a) of the tubular member are
20 arranged at a suitable distance in the vertical direction (Z-Z) from the bottom of the cup (33) .
14. Mould according to Claim 10, characterized in that the said lower radial holes (32a) of the tubular member
25 are arranged at a distance in the vertical direction (Z-Z) from the bottom of the blind hole (33) such as to emerge inside the seat (11, 21) for casting the object to be made ,
30 15. Mould according to Claim 11, characterized in that said seats (11, 21) are shaped in the manner of a case (100) of a watch.
16. Mould according to Claim 15, characterized in that 35 said vertical through-hole (110) is centred with respect to the said case (10D) .
17. Mould according to claim 4, characterized in that said vertical through-hole (110) is the seat for • the watch mechanism.
18. Mould according to Claim 16, characterized in that it comprises first transverse seats (15 25) which are formed in the respective half"moulds (1O 7 20) and arranged in positions such that the opposite ends emerge outside the respective half-moulds and inside the central hole (.12 , 11), respectively, said seats being able to contain a corresponding pin (55a) able to produce, during casting, the formation of a transverse hole (120) which passes through the object (100) from the side surface (lOOa) to the inside of the vertical through-hole (110) .
19. Mould according to Claim 18, characterized in that said transverse through-hole is the seat for the spindle (130a) operating the hands of the watch.
20. Mould according to Claim 15, characterized in that it envisages second transverse seats (155) which pass through the respective half-moulds (10, 20) in the transverse direction in a location corresponding to that of the strap holder cross-pieces (101) , said seats being suitable for a corresponding pin (155a) able to produce, during casting, the formation of a transverse hole (120) which passes through said cross pieces (101) so as to form a through-seat (lola) in them.
21. Tool for moulds for producing porcelain objects ' with at least one through-hole (110) , characterized in that it comprises a tubular -member (31) which is open at the opposite ends and provided with first upper holes (32a) and second lower holes (32b) formed in the side surface of the tube (31) at suitable distances from the respective opposite ends of the said tube.
22. Tool according to Claim 21, characterized in that the tubular member (31) is associated with a cup (33) for containing the mixture (P) of liquid porcelain, arranged on its top part .
23. Tool according to Claim 22, characterized in that said upper radial holes (32a) of the tubular member are arranged at a suitable distance in the vertical direction (Z-Z) from the bottom of the cup (33) and are able to cause the entry o£ the porcelain (P) inside the tubular member.
24. Tool according to Claim 21, characterized in that said tubular member has an inner diameter such as to cause casting of the porcelain (P) and simultaneous expulsion of air (A) from the open top end. |
METHOD AND ASSOCIATED MOULD AND TOOL FOR PRODUCING PORCELAIN OBJECTS WITH AT LEAST ONE THROUGH-HOLE
DESCRIPTION The present invention relates to a method, a mould and an associated tool for producing porcelain objects with at least one through-hole.
In the technical sector relating to the production of porcelain objects other than plates and trays it is known to use plaster moulds in which the form of the object to be made is reproduced and inside which a mixture of liquid porcelain is cast.
It is also known that these moulds are provided with holes for introducing the casting mixture and holes for ventilation of the air which must escape from the mould so as to allow it to be filled with the porcelain and prevent trapping of air pockets which could result in breakage of the part during firing. After a certain drying time, the object is removed from the mould and hand-finished by means of a series of steps involving firing, dipping in a surface finish glaze and firing at 1400°C after being placed on supports made of refractory material. This conventional technique, although fulfilling its function, is however not suitable for producing objects which require through-holes, as, for example, with watch cases which must have a through-opening inside which the mechanism is inserted. In addition to this, placing the object on support surfaces during firing of the glaze causes removal thereof with a consequent finishing defect in the finished article, which in these zones has a rough surface which is easily soiled and can no longer be decorated, this being particularly crucial with regard
to watch cases which must always remain visible. The technical problem which, is posed, therefore, is to develop a, method for producing porcelain objects which have at least one through-hole. In connection with this problem a further requirement is that this through-hole may represent a precise reference point for the subsequent processing operations and/or assembly of the finished part, as, for example, with a watch case to which the associated mechanism must be fitted,
A further object of the present invention is to provide a tool and a mould which are able to allow the production of porcelain objects with at least one through-hole . These results are achieved according to the present invention by a method for producing porcelain objects with at least one through-hole, according to the characteristic features of Claim 1. The present invention relates furthermore to a mould according to the characteristic features of Claim 10 for implementing the said method and to an associated tool according to the characteristic features of Claim 21. Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the aσclompanying drawings in which:
- Figure 1 is an exploded perspective view of a mould for porcelain objects according to the present invention;
- Figure 2 is a partially sectioned schematic view of the mould according to Fig. 1 in the open condition;
- Figure 3 is a schematic cross-section through the mould according to Fig. 1 in the closed condition, during casting;
- Figure 4 is a perspective view of a watch case obtained with the method according to the present invention; and,
- Figure 5 is a partially sectioned schematic view of the watch according to Fig. 4 in the finished condition.
As shown in Fig. 1 and assuming solely from the sake of convenience of the description and without a restrictive meaning a set of three reference axes in the longitudinal direction X-X, transverse direction Y- Y and vertical direction Z-Z, respectively, and a top part and bottom part arranged as shown in the figures, a mould for porcelain objects according to the present invention comprises essentially a bottom half-mould 10 and a top half-mould 20 which have a matching shape and can be joined together in the vertical direction Z-Z by means of projections 10a and corresponding holes 20a formed in suitable zones of the two facing surfaces of the respective half-moulds. Both the said contact surfaces of the two half-moulds have, formed in them, the associated half-seat 11, 21 corresponding to the final form of the part and intended to be filled with the casting mixture P of porcelain. Both the half-moulds 10, 20 also have a respective hole 12, 22 which are coaxial with each other; the hole 12 in the bottom , half-mould 10 is blind, while the hole 22 in the top half-mould 20 is a through-hole. Via said holes 12, 22 it is possible to introduce a tool 30 for supplying the liquid mixture P of porcelain to the half-seats 11, 21; this tool 30 comprises a tubular member 31 which is open at the opposite ends and has upper holes 32a and lower holes 32b which are formed in the side surface of the tube at suitable distances from the respective opposite ends of the said
tube. The top part of the tubular member 31 has, associated with it, a cup 33 for containing the mixture P of liquid porcelain which is able to enter into the tube 31 via the upper radial holea 32a. In the example shown in figures, the cup 33 is integral with the tube 31, but in an alternative embodiment (not shown) it is envisaged that said cup 33 may be separate and provided- with a through-hole in the bottom for coaxial mounting on the tube 31 during assembly of the mould on which it will rest during the working process. In this case the cup may also be made of plaster like the mould instead of steel as with the tubular member 31. The distances of the lower radial holea 32b from the bottom end of the tubular member 31 and the depth of the blind hole 12 of the bottom half-mould 12 are such as to cause the liquid porcelain P to flow out into the seats 11, 21 so as to fill them. Using the tool and the mould described above it is therefore possible to produce a porcelain objeot with a through-hole such as, for example, the watch case 100 in which a through-hole 110 is formed, by means of a method which envisages the following steps :
- preparation of a bottom half-mould 10 having a half- seat 11 with a form corresponding to that of the object to be obtained;
- provision of a blind hole 12 with a vertical axis in the half-seat 11 of this bottom half-mould 10;
- preparation of a top half-mould 20 having a half-seat 21 with a form corresponding to that of the object to be obtained;
- provision, in this top half-mould 20, of a through- hole 22 coaxial with the blind hole 12 of the bottom half-mould 10; - provision of a tubular member 31 open at the opposite
ends and provided with upper holes 32a and lower holes 32b formed on the side surface at suitable distances from the respective opposite ends of the tube;
- provision of a cup 33 for supplying the liquid porcelain P to be cast and with a hole in its bottom surface;
- joining together of the two half-moulds 10, 20 in the vertical direction Z-Z;
- insertion of the tubular member 31 inside the two half-moulds, i.e. top half-mould 20 and bottom half- mould 10, via the respective through-hole 22 and blind hole 12;
- mounting of the cup 33 on the tube part 31 projecting from the top half-mould 20; - casting of the liquid porcelain P inside the cup 33;
- penetration of the liquid porcelain P inside the tube 31 via the upper radial holes 32a;
- flowing out of the porcelain P into the seat 11, 21 through the lower radial holes 32b; - expulsion of the air A from the mould through the upper opening in the tube 3i ;
- drying of the part 100 with hole 110 obtained;
- opening of the mould;
- extraction o£ the part . It can therefore be seen, how the tool, the mould and the method according to the present invention allow the production of porcelain parts 100 with a through-hole 110 which, in the particular example of a watch case illustrated, is arranged coaxially in the centre thereof so as to form also a precise reference point for the subsequent operations involving:
- milling of the hole 110 so as to widen it to a size suitable for containing the (analog or digital ) mechanism of the watch according to Fig. 5; - application of the glaae and subsequent firing at
1400° C, for which step the case 100 may be gripped, by means of said hole 110, making it possible to avoid resting the part on refractory supports with a consequent reduction in the defects in the finished parts.
In the particular instance of a watch case it is also envisaged that the method according to the present invention may also comprise the following steps:
- provision of first transverse seats 15, 25 inside the respective half-moulds 10, 20, arranged so that the opposite ends emerge outside and inside the central hole 12, 22;
- insertion, inside the seat 15, 25, of a pin 55 able to produce, during casting, the formation of a transverse hole 120 which passes through the case 100 in the direction Y-y from the side surface 100a to the inside of the hole 110 so as to allow, after completion of the processing operations, insertion of the spindle 130a of the crown 130 for operating the hands 140. Similarly it is also possible to envisage transverse seats 155 which pass through the respective half-moulds 10, 20 in the transverse direction Y-Y in a position corresponding to that of the strap holder cross-pieces 101 (Pig. 4) so as to form a through-seat 101a passing through them and able to allow the insertion of a movable clip 102 for fastening the two male and female parts of a strap 2 to the respective pins as shown in the bottom part of Fig. 5; the top part of the latter instead shows a complete strap 3 which passes underneath the case 100 and above the two opposite cross-pieces 101.
Although described in connection with porcelain, it is envisaged that the method, mould and tool according to the present invention may be used also for objects made of equivalent materials such as a ceramic material or
the like.