WARE FORMING METHOD AND APPARATUS

WARE FORMING METHOD AND APPARATUS

This invention concerns a ware forming method and apparatus, and particularly but not exclusively a method and apparatus for removing a piece of shaped clay from a mould .

Conventionally holloware and flatware have been shaped on a roller machine. With such a machine a plaster of paris mould is loaded onto the machine. Typically the mould is held in a metal mould carrier. A piece of clay is placed onto the mould hich is then spun and a counter-rotating shaped roller head is brought into contact with the clay to provide the required shape..^' The ware carry ng mould is then removed from the machine and placed in a drier to octaiπ mould release. Disadvantages are encountered wi h t is system in that, as the shaped clay is held in the moulds during drying a large number of moulds are required which thus occupy a relatively large area in a production area.

According to the present invention there is provided a method of forming clay ware, the method comprising locating a piece of clay on a mould, shaping the clay on the mould, locating a former against the shaped clay on the opposite side thereof to the mould, the former being shaped to correspond substantially to the shape of the clay so as to provide a close fit thereagainst, and blo ing a fluid through the mould to blow the shaped clay off the mould and onto the former.

The clay is preferably shaped by a roller head.

The invention also provides a method of removing a piece of shaped clay from a mould, the method comprising locating a former against the shaped clay on the opposite side thereof to the mould, the former being shaped to correspond substantially to the shape of the clay so as to provide a close fit thereagainst, and blowing a fluid through the mould to blow the shaped clay off the mould and onto the former.

The fluid preferably comprises air, and the air may be warmed.

A resistive force is preferably applied to the "^'or er against the clay, said resistive force being slightly less than the force applied by the fluid being blown through the mould.

The resistive force may be applied by a pneumatic cylinder, or a resilient member such as a spring.

Suction may be applied through the former to hold the shaped clay thereagainst following removal from the mould . Air, which may be warmed, is preferably blown through the mould following removal of the shaped clay, to condition the mould.

First detection means may be provided for sensing when the shaped clay has been blown off the mould, and said means may comprise second detection means for sensing a reduction in the back pressure in the mould. The first detection means may be connected to means for automatically separating the mould and former hen the shaped clay has moved onto the latter.

The mould may be rotated relative tc the former once fluid is being blo n through the mould, ereby to shear the ater film be een e mould and the clay.

The mould may be made of an acrylic plastics material and preferably an acrylic bead. The plastics material is preferably mounted on a carrier. The carrier may be made of a plastics material such as acrylic, cr of metal. Alterna ively the mould may be made of plaster of paris.

According to the present invention there is further provided a former usable in a method according to any of the preceding eleven paragraphs. Openings are preferably provided through the former to permit the article of clay to be held thereon by suction.

An embodiment of the present invention will now be described by way of example only, with reference to Figs. 1-3 of the accompanying drawings which show sequential stages of a method according to the present invention using apparatus according to the present invention.

The drawings show apparatus for removing an item of the shaped clay from a mould. Tne clay is. m the form of an item of flatware such as a plate. The drawings sho a permeable synthetic mould 10. The mould 10 is made from an acrylic bead and has an upper surface shaped to correspond to the upper surface of a plate. The mould 10 is mounted on a carrier 12 also made of acrylic .

In a method according to the present invention, a piece of clay is located on the mould 10. The mould 10 is subsequently spun and a roller head (not shown) is used to form the piece of clay into a required shape 14.. A former 16 is lo ered onto the c1a\ 14. The former 16 has a lo er face as shown in the dra ings, with a shape corresponding to the rear profile of the clay 14 sucn that the former 16 provides a close fit thereagainst. A downward force is then applied to the former 16 whilst suction is provided therethrough. Simultaneously air is blown through the mould 10 to ards the clay 14.

A plurality of passages 18 extend through the former 16 and connect with a chamber 20 which has an outlet 22 connectible to a suction pump or other source of reduced pressure. A chamber 24 is provided beneath the mould 10, between the mould 10 and the carrier 12 ith an inlet 26 connectible to a source of above atmospheric pressure.

The force applied to the former 16 is arranged to be slightly less than that applied tc the clay 14 by air being blown through the mould 10. The force may be applied by a pneumatic cylinder or a resilient member.

Once the clay 14 has been blown off the mould 10 by air passing therethrough, which air may be warmed, the mould 10 and former 16 can be separated with the clay 14 being held on the latter by the suction through the passages 18. The former 16 can then be turned over with the shaped clay 14 thereon to dry. As the clay is not on the mould to which it may have become attached, and as the former may be made of a more heat resistant material than plaster of paris, the clay can be dried very quickly. Warm air may be blo n through the emptv mould 10 to condition same by removing any moisture or other materials.

It has been found to be advantageous to rotate the mould, usually a partial turn, relative to the former whilst air is being blown through the mould. This rotation shears the water film between the mould and the clay .

There is thus described a method and apparatus which provide considerable advantages over existing arrangements. As_r' the former holds the clay 14 against the mould 10 as the clay 14 is blown thereoff, this prevents distortion of the clay 14. Furthermore, this "sandwiching" arrangement prevents air passing through the mould 10 and lifting for example an edge of the clay 14 to provide a ready escape thereby preventing further release action. Such an occurance would provide for uneven removal of the clay 14 from the mould 10 and probably also distortion of the clay 14. As a result of this "sandwiching" the air tends to form a "wedge" between the clay and the mould forcing the whole of the clay 14 off the mould substantially at once to provide even release. As the clay is removed rapidly from the relatively expensive mould following forming, there is not the requirement to use a large number of moulds. Accordingly, a number of the above mentioned disadvantages are overcome. Furthermore, tnis system lends itself to short runs of different shaoed articles.

Various modifications may be made without departing from the scope of the invention. For example, the former may be positioned with its shaped face pointing upwards such that the mould carrving shaped clav is lowered onto the former. In such an instance, suction is not required through the former to hold the clay thereon. Whilst the above described example uses an acrvlic mould the invention is also reacilv aoplicaole to plaster of pans moulds, or moulds made,^' from any suitable permeable material.

The method can be used with different items of ware and different forming techniques. Tne method and apparatus readily lend themselves to automatic oDeration which could be arranged to provide a required mould and corresDonding former as programmed by an operator. eans may be provided to indicate when the clay has been blown off the mould onto the former, perhaσs by detecting a drop in back pressure in the mould. Said indication means may be connected to means for automatically separating the former and mould once this 'blo ing off has taken place. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.